Supplementary File 6: Jaccard similarity scores,,,,
,,,,
,Segment1,Segment2,similarity,matching_words
1,". In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.944444444,"in, the, case, of, sars-cov,, horseshoe, bat,, member, rhinolophidae, family,, was, considered, natural, host, and, principal, reservoir.5"
2,"Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.928571429,"on, the, large, number, of, infected, people, that, were, exposed, to, wet, animal, market, in, wuhan, city,, china,, it, is, suggested, this, likely, zoonotic, origin, covid-19"
3,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.92,"the, phylogenetic, tree, shows, that, sars-cov-2, has, closest, evolutionary, relationship, with, bat-sl-cov-2, at, scale, of, complete, virus, genome,, and, less, similarity, to, pangolin-cov"
4,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.92,"phylogenetic, tree, shows, that, sars-cov-2, has, the, closest, evolutionary, relationship, with, bat-sl-cov-2, at, scale, of, complete, virus, genome,, and, less, similarity, to, pangolin-cov"
5,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.888888889,"our, retrospective, analysis, of, scientific, data, supports, the, hypothesis, that, sars-cov-2, is, indeed, a, naturally, occurring"
6,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.823529412,"in, a, study, published, the, journal, nature, 201510, warned, of, possible, pandemic, relation, with"
7,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.",0.823529412,"a, study, published, in, the, journal, nature, 201510, warned, of, possible, pandemic, relation, with"
8,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.714285714,"studies, compared, the, first, covid-19, genome, to, bat, coronavirus, and, verified, that, sequence, was, 96.2%, identical,, a, very, high, percentage"
9,Bats are hosts of many coronaviruses,"Bats are natural hosts of many of the known  

coronaviruses",0.666666667,"bats, are, hosts, of, many, coronaviruses"
10,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.6,"virus, most, probably, has, its, ecological, reservoir, in, bats"
11,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.548387097,"that, the, similarity, between, sars-cov-2, and, bat, cov, ratg13, (or, guangdong, pangolin, cov), is, larger, than, same"
12,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.515151515,"coronavirus, disease, (covid-19), is, easily, trans-, missible, and, very, contagious, from, animals, to, human, beings, through, aerosols,"
13,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.447368421,"analyzed, throughout, genome, 96.2%, overall, sequence, identity, bat, cov, suggesting, that, and, human, sars-cov-2, might, share, ancestor"
14,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.447368421,"genome, analyzed, throughout, bat, cov, and, 96.2%, overall, sequence, identity, suggesting, that, human, sars-cov-2, might, share, ancestor"
15,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.444444444,"we, that, the, similarity, between, sars-cov-2, and, bat, cov, ratg13, (or, guangdong, pangolin, cov), is, viruses"
16,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.444444444,"is, we, similarity, sars-cov-2, and, bat, cov, ratg13, (or, guangdong, pangolin, cov), the, between, viruses, that"
17,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.4,"the, sars-cov-2, genome, was, found, to, 96.2%, identical, bat, cov"
18,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.4,"was, found, the, genome, sars-cov-2, 96.2%, identical, to, bat, cov"
19,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.396551724,"on, in, the, report, and, leaked, january, ccdc, of, positive, samples, collected, 1, 12,, 2020, were, linked, to, western, side, huanan, market., located"
20,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.396551724,"leaked, ccdc, report, january, 2020, positive, samples, collected, on, 1, and, 12,, were, linked, to, of, located, in, the, western, side, huanan, market."
21,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.387096774,"the, genome, of, sars-cov-2, shares, identity, that, sars-cov, is, identical, to, bat"
22,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.387096774,"that, the, genome, of, sars-cov-2, is, identical, to, bat, shares, identity, sars-cov"
23,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.387096774,"it, is, that, bats, the, likely, reservoir, hosts, for, as, to, bat"
24,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.387096774,"the, to, bat, it, is, likely, that, bats, as, reservoir, hosts, for"
25,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.385964912,"bat, sars, cov, wiv1, and, the, same, origin, are, into, 2, clusters, while, all, 16, sars-cov-2, representatives, grouped, cluster, with, ratg13, guangdong"
26,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.385964912,"are, into, 2, clusters, and, while, all, 16, sars-cov-2, representatives, grouped, with, bat, cov, ratg13, guangdong, cluster, the, same, origin, sars, wiv1"
27,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.368421053,"that, the, similarity, between, sars-cov-2, and, bat, cov, ratg13, (or, guangdong, pangolin, cov), is"
28,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.368421053,"is, similarity, sars-cov-2, and, bat, cov, ratg13, (or, guangdong, pangolin, cov), the, between, that"
29,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.366666667,"the, whole, genome, of, sars-cov-2, with, sars-cov, and, is, to, bat"
30,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.366666667,"with, the, sars-cov, and, sars-cov-2, is, to, bat, of, whole, genome"
31,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.363636364,"the, virus, has, single-stranded, positive-sense, rna, of, 30, which, to, 99%, that, coronavirus, from, and, horseshoe"
32,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.363636364,"the, virus, has, 30, single-stranded, positive-sense, rna, which, to, 99%, that, of, and, coronavirus, from, horseshoe"
33,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.357142857,"a, from, the, has, identified, coronavirus, 99%, similarity, with, sars-cov-2"
34,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.357142857,"a, coronavirus, identified, from, the, has, 99%, similarity, with, sars-cov-2"
35,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",Bats are likely reservoir hosts for SARS-CoV-2,0.35,"bats, are, likely, reservoir, hosts, for, sars-cov-2"
36,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.333333333,"the, pangolin, is, considered, to, be, intermediate"
37,"Bats are natural hosts of many of the known  

coronaviruses","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.333333333,"bats, are, natural, of, the"
38,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.333333333,"the, have, been, from, source, in, market, or, infected, may"
39,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.333333333,"source, from, infected, or, in, the, market, may, have, been"
40,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.333333333,"first, patients, were, seafood, market, in, wuhan, city,, hubei, province,, china"
41,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","Bats are natural hosts of many of the known  

coronaviruses",0.333333333,"bats, are, the, natural, of"
42,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.333333333,"the, banal, related, to, sars-cov-2,, as, measured, by, highest, average, genetic, is, bat"
43,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.333333333,"related, bat, to, sars-cov-2,, as, measured, by, highest, average, genetic, is, banal, the"
44,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.333333333,"first, in, patients, were, seafood, market, wuhan, city,, hubei, province,, china"
45,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.323529412,"our, findings, the, that, bats, are, more, likely, hosts, for, than"
46,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.323529412,"the, our, findings, that, bats, are, more, likely, hosts, for, than"
47,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.321428571,"the, of, sars-cov-2, is, identical, with, and, to, sars-cov"
48,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.321428571,"the, of, sars-cov-2, with, sars-cov, and, is, identical, to"
49,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.32,"that, sars-cov-2, is, not, a, or, manipulated, virus."
50,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.32,"that, sars-cov-2, a, is, not, manipulated, or, virus."
51,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.32,"the, this, probable, bat, or, pangolin, origin, of"
52,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.32,"this, the, probable, bat, or, pangolin, origin, of"
53,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.318181818,"the, sources, of, sars-cov-2, are, animal, and"
54,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.318181818,"the, animal, sources, of, sars-cov-2, are, and"
55,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.314285714,"phylogenetic, analysis, that, the, belongs, to, genus, betacoronavirus,, which, includes, and"
56,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.314285714,"the, phylogenetic, analysis, that, belongs, to, genus, betacoronavirus,, which, includes, and"
57,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.3125,"bat, is, closer, to, covs."
58,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.3125,"the, coronaviruses, to, date, are, closely, related, sars-cov-2, all, bat"
59,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.3125,"all, sars-cov-2, to, date, are, closely, related, coronaviruses, bat, the"
60,"According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.3125,"to, is, closer, bat, covs."
61,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",hese reservoirs are the bats,0.307692308,"bats, are, the, reservoirs"
62,hese reservoirs are the bats,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.307692308,"reservoirs, are, the, bats"
63,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.307692308,"hypothesis, that, sars-cov-2, the, result, of, spillover, into"
64,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.307692308,"the, hypothesis, that, sars-cov-2, result, of, spillover, into"
65,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.307692308,"another, study, sars-cov-2, might, be, the, and, an"
66,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.307692308,"another, study, might, be, the, sars-cov-2, and, an"
67,Bats are hosts of many coronaviruses,Bats are likely reservoir hosts for SARS-CoV-2,0.3,"bats, are, hosts"
68,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.3,"the, and, closely, related, to, discovered, in, southern, china"
69,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.3,"the, discovered, to, closely, related, in, southern, china, and"
70,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.3,"this, that, bats, are, the, more, likely, sars-cov-2, than"
71,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.3,"this, the, that, bats, are, more, likely, sars-cov-2, than"
72,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.3,"that, sars-cov-2, has, with, bat-sl-cov-2, and, similarity, to, pangolin-cov"
73,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.3,"that, sars-cov-2, has, similarity, to, bat-sl-cov-2, and, pangolin-cov, with"
74,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.297297297,"at, ratg13,, which, was, in, rhinolophus, affinis, yunnan, province,, the, level"
75,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.297297297,"and, the, virus, was, transmitted, from, bats, to, humans,, possibly, a"
76,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.297297297,"to, a, virus, from, bats, and, was, transmitted, humans,, possibly, the"
77,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.297297297,"at, the, level, ratg13,, which, was, in, rhinolophus, affinis, yunnan, province,"
78,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.296296296,"the, animal, of, are, bats, and, be, to"
79,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.296296296,"bats, of, and, are, to, be, the, animal"
80,"Bats are natural hosts of many of the known  

coronaviruses","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.294117647,"bats, natural, hosts, of, the"
81,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",Bats are likely reservoir hosts for SARS-CoV-2,0.294117647,"bats, are, hosts, for, sars-cov-2"
82,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","Bats are natural hosts of many of the known  

coronaviruses",0.294117647,"bats, the, natural, hosts, of"
83,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.292682927,"the, results, various, clustering, that, sars-cov-2, genomes, to, a, cluster, bat, pangolin"
84,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.291666667,"the, covid-19, is, to, in, seafood, market"
85,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.291666667,"that, is, sars-cov-2, a, laboratory, construct, or"
86,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.291666667,"covid-19, is, to, the, seafood, market, in"
87,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.291666667,"that, sars-cov-2, is, a, laboratory, construct, or"
88,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.290909091,"strong, to, sars-cov-2, the, this, that, spike, protein, binding, human-like, ace2, is, result, of, natural, selection"
89,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.290909091,"the, binding, of, sars-cov-2, spike, protein, to, ace2, is, result, natural, selection, human-like, that, this, strong"
90,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.290909091,"that, the, between, sars-cov-2, and, bat, cov, ratg13, (or, guangdong, pangolin, is, larger, than, sars, same"
91,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.290909091,"that, the, between, sars-cov-2, and, bat, cov, ratg13, (or, guangdong, pangolin, is, larger, than, viruses, same"
92,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.290909091,"and, sars-cov-2, bat, cov, ratg13, guangdong, pangolin, that, the, between, same, sars, is, larger, than, (or"
93,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.290909091,"viruses, and, sars-cov-2, bat, cov, ratg13, guangdong, pangolin, that, the, between, same, is, larger, than, (or"
94,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.288135593,"found, in, horseshoe, bats, laos, to, nucleotide, and, amino, acid, ratg13, (85.5%, 89.2%,, respectively), mp789, (86.6%, 96.9%,"
95,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.288135593,"nucleotide, and, amino, acid, in, found, horseshoe, bats, laos, to, ratg13, (85.5%, 89.2%,, respectively), mp789, (86.6%, 96.9%,"
96,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.285714286,"of, the, bats, are, natural, reservoirs"
97,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.285714286,"bats, are, the, natural, reservoirs, of"
98,COVID-19 is a zoonotic virus,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.285714286,"is, a, zoonotic, virus"
99,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.285714286,"the, closely, related, to, coronaviruses, isolated, from, bats"
100,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.285714286,"isolated, from, to, closely, related, coronaviruses, bats, the"
101,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",COVID-19 is a zoonotic virus,0.285714286,"virus, is, a, zoonotic"
102,Bats are hosts of many coronaviruses,"bats are also important reservoir species for a great 

range of coronaviruses",0.285714286,"bats, are, of, coronaviruses"
103,"natural selection in humans  

following zoonotic transfer","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.285714286,"natural, in, humans, following, zoonotic, transfer"
104,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","natural selection in humans  

following zoonotic transfer",0.285714286,"natural, in, zoonotic, humans, following, transfer"
105,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.28125,"., in, many, bat, coronaviruses, genetic, to, sars-cov, and"
106,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.28125,"., sars-cov, and, to, bat, coronaviruses, in, genetic, many"
107,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.28,"bats, be, the, hosts, of, sars-, may"
108,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.28,"bats, may, be, the, hosts, of, sars-"
109,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.28,"the, to, be, most, likely, intermediate, hosts."
110,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.28,"to, be, the, most, likely, intermediate, hosts."
111,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.277777778,"analysis, that, sars-cov-2, has, the, of, virus, and, to, pangolin-cov"
112,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.277777778,"banal, viruses, have, a, furin, cleavage, site, at, the, s1/s2"
113,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.277777778,"the, banal, viruses, have, a, furin, cleavage, site, at, s1/s2"
114,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.277777778,"the, of, natural, origin, a, past, human, history, viral, and"
115,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.277777778,"viral, and, past, human, history, a, natural, origin, of, the"
116,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.277777778,"analysis, of, to, has, that, sars-cov-2, the, pangolin-cov, and, virus"
117,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.275862069,"are, the, reservoir, a, of, covs,, including, and"
118,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.275862069,"the, genome, of, sars-cov-2, 80%, identical, to, bat"
119,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.275862069,"are, the, reservoir, of, a, covs,, including, and"
120,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.275,"in, the, of, palm, civets, as, intermediate, host, sars, a, found, that, virus, taken, from, humans, were, to, human, and, sequence, adapted"
121,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.275,"the, of, and, civets, were, intermediate, host, that, virus, from, palm, a, sequence, found, in, human, sars, taken, humans, as, adapted, to"
122,"Bats are natural hosts of many of the known  

coronaviruses",hese reservoirs are the bats,0.272727273,"bats, are, the"
123,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.272727273,"that, the, started, from, a, market, animals, in, wuhan,, to, humans, and"
124,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.272727273,"and, the, novel, has, approximately, identity, of, bat, respectively."
125,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.272727273,"of, the, novel, has, approximately, and, identity, bat, respectively."
126,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.272727273,"that, the, started, in, and, to, humans, from, animals, a, market, wuhan,"
127,hese reservoirs are the bats,"Bats are natural hosts of many of the known  

coronaviruses",0.272727273,"are, the, bats"
128,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.272727273,"of, has, not, yet, been, identified,, that, the, a"
129,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.272727273,"it, is, that, the, most, for, similar, to, bat"
130,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.272727273,"the, that, of, has, not, yet, been, identified,, a"
131,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.272727273,"that, it, is, most, similar, to, the, bat, for"
132,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.272727273,"we, that, the, sars-cov-2, bat, cov, ratg13, guangdong, same"
133,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.272727273,"we, that, sars-cov-2, the, same, bat, cov, ratg13, guangdong"
134,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.27027027,"of, 96.2%, similarity, a, genome, bat, found, in, yunnan, province"
135,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.27027027,"the, of, covid-19, were, associated, with, huanan, seafood, market, in"
136,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.27027027,"of, the, covid-19, in, were, associated, with, huanan, seafood, market"
137,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.27027027,"a, bat, found, in, yunnan, province, genome, similarity, of, 96.2%"
138,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.27027027,"we, thus, that, sars-cov-2, the, same, with, bat, cov, ratg13"
139,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.27027027,"bat, cov, ratg13, the, same, with, sars-cov-2, we, thus, that"
140,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.269230769,"bats, are, the, natural, reservoir, host, of"
141,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.269230769,"a, who, was, at, seafood, market, in, wuhan, city,, hubei, province,, china, that, were"
142,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.269230769,"bats, are, the, natural, host, reservoir, of"
143,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.269230769,"that, was, in, who, were, at, a, seafood, market, wuhan, city,, hubei, province,, china"
144,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.269230769,"the, of, sars-cov-2, is, with, bat-sl-cov-2,, and"
145,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.268292683,"genome, the, was, to, bat, cov, 96.2%, sequence, identity, that, sars-cov-2"
146,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.268292683,"was, that, the, genome, sequence, sars-cov-2, 96.2%, to, bat, cov, identity"
147,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.266666667,"the, of, sars-cov-2, is, with, and, to, sars-cov"
148,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.266666667,"the, virus, is, to, and, that, had, in"
149,"bats are also important reservoir species for a great 

range of coronaviruses",Bats are likely reservoir hosts for SARS-CoV-2,0.266666667,"bats, are, reservoir, for"
150,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.266666667,"the, natural, origin, of, sars-cov-2, as, a, from"
151,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.266666667,"the, other, viruses, closely, related, to, were, in"
152,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.266666667,"analysis, of, data, the, that, sars-cov-2, a, virus"
153,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.266666667,"is, the, to, that, in, had, virus, and"
154,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.266666667,"sars-cov-2, has, a, natural, origin, and, animal, or"
155,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.266666667,"the, sars-cov-2, as, a, of, from, natural, origin"
156,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.266666667,"were, viruses, in, closely, related, to, the, other"
157,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.266666667,"sars-cov-2, has, a, natural, animal, origin, and, or"
158,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.266666667,"a, analysis, of, data, that, sars-cov-2, the, virus"
159,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.266666667,"with, the, sars-cov, and, sars-cov-2, is, to, of"
160,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.264705882,"and, in, were, a, seafood, market, hubei, province,, china"
161,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.264705882,"were, a, seafood, and, market, in, hubei, province,, china"
162,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.264705882,"is, the, closely, related, virus, to, sars-cov-2, in, covid-19"
163,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.264705882,"the, covid-19, is, sars-cov-2, to, closely, related, virus, in"
164,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Bats are natural hosts of many of the known  

coronaviruses",0.263157895,"of, the, bats, are, natural"
165,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.263157895,"that, is, the, of, sars-cov-2"
166,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.263157895,"in, the, of, that, pangolin, gave, new, features, virus, hace2."
167,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.263157895,"that, in, pangolin, gave, the, virus, new, features, of, hace2."
168,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.263157895,"that, sars-cov-2, is, of, the"
169,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.261904762,"the, sars-cov-2, of, genome, sequence, is, 96.2%, identical, to, that, bat"
170,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.261904762,"the, sample, by, was, taken, from, a, at, huanan, market, of"
171,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.261904762,"the, virus, in, bats, and, to, from, a, market, wuhan,, china"
172,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.261904762,"and, the, virus, from, bats, to, a, market, in, wuhan,, china"
173,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.261904762,"who, the, to, that, virus, started, in, animals, and, jumped, humans"
174,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.261904762,"that, the, virus, started, in, and, jumped, to, humans, who, animals"
175,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.261904762,"that, the, genome, sequence, of, sars-cov-2, is, 96.2%, identical, to, bat"
176,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.261904762,"of, a, at, the, huanan, market, was, by, from, sample, taken"
177,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.261904762,"this, the, fig., that, bats, are, more, hosts, for, sars-cov-2, than"
178,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.261904762,"fig., this, the, sars-cov-2, that, bats, are, more, hosts, for, than"
179,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.260869565,"coronaviruses, are, a, large, of, viruses"
180,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.260869565,"bats, the, reservoirs, for, of, sars"
181,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.260869565,"the, coronavirus, from, has, with, sars-cov-2"
182,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.260869565,"coronavirus, from, the, has, with, sars-cov-2"
183,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.260869565,"the, sars-cov-2, genome, to, identical, bat"
184,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.260869565,"that, sars-cov-2, is, naturally, of, the"
185,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.260869565,"of, the, sars, bats, reservoirs, for"
186,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.260869565,"the, covid-19, is, to, be, in"
187,"atural  

selection in an animal host before zoonotic  

transfer;","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.260869565,"in, an, animal, host, before, zoonotic"
188,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.260869565,"coronaviruses, are, viruses, a, large, of"
189,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.260869565,"is, the, to, be, in, covid-19"
190,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.260869565,"the, genome, sars-cov-2, identical, to, bat"
191,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.260869565,"of, the, that, sars-cov-2, is, naturally"
192,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.259259259,"whole, genome, sars-cov-2, is, 96%, identical, to"
193,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.259259259,"the, animal, of, sars-cov-2, and, be, to"
194,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.259259259,"a, coronavirus, from, the, to, with, sars-cov-2"
195,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.259259259,"is, 96%, identical, to, sars-cov-2, whole, genome"
196,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.259259259,"sars-cov-2, to, be, of, animal, and, the"
197,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.259259259,"that, is, from, an, animal, to, a"
198,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.259259259,"to, the, with, a, coronavirus, from, sars-cov-2"
199,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.259259259,"that, is, from, a, an, animal, to"
200,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.259259259,"the, sources, of, are, animal, hosts, and"
201,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.259259259,"infected, are, currently, the, main, sources, of"
202,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.259259259,"animal, hosts, and, are, the, sources, of"
203,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.258064516,"were, seafood, wholesale, market, in, hubei, province,, china"
204,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.258064516,"the, covid-19, huanan, seafood, wholesale, market, in, wuhan"
205,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.258064516,"covid-19, the, huanan, seafood, wholesale, market, in, wuhan"
206,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.257142857,"the, sars-cov, sars-cov-2, is, to, bat, of, genome, sequence"
207,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.257142857,"the, genome, to, bat, that, sequence, was, 96.2%, a"
208,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.257142857,"the, genome, sequence, of, sars-cov-2, is, to, bat, sars-cov"
209,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.257142857,"was, that, the, genome, sequence, 96.2%, to, a, bat"
210,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.257142857,"the, that, sars-cov-2, has, of, virus, and, to, pangolin-cov"
211,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.257142857,"sars-cov-2, the, same, with, bat, cov, ratg13, or, guangdong"
212,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.257142857,"of, to, has, that, sars-cov-2, the, pangolin-cov, and, virus"
213,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.256410256,"genome, 96.2%, sequence, identity, bat, cov, ratg13,, that, sars-cov-2, a"
214,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.256410256,"that, genome, sequence, sars-cov-2, 96.2%, a, bat, cov, ratg13,, identity"
215,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.256410256,"ratg13,, which, was, found, in, rhinolophus, affinis, yunnan, 96.2%, genome"
216,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.256410256,"96.2%, genome, ratg13,, which, was, rhinolophus, affinis, found, in, yunnan"
217,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.255813953,"the, in, of, rbd, similar, to, that, sars-cov-2, this, was, virus"
218,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.255813953,"this, in, the, of, that, sars-cov-2, was, to, rbd, similar, virus"
219,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.255813953,"sars-cov-2, is, to, originated, in, the, bat, cov, ratg13, guangdong, pangolin"
220,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.255813953,"is, sars-cov-2, bat, cov, ratg13, guangdong, pangolin, to, the, originated, in"
221,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.25,"of, 96.2%, to, a, genome, sequence, ratg13,, was, bat, found"
222,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.25,"the, covid-19, genome, to, bat, and, that, sequence, was, 96.2%"
223,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",hese reservoirs are the bats,0.25,"the, bats, are, reservoirs"
224,"In the 

case of MERS, dromedaries were the principal host.","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.25,"in, the, case, of, were"
225,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.25,"bats, and, the, natural, of"
226,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.25,"bats, the, natural, of, and"
227,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.25,"the, sars-cov-2, and, of, genome, is, identical, to, that, bat"
228,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.25,"geographic, with, and, of, lineage, at, the, huanan, market, in, november"
229,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.25,"the, of, with, lineage, and, geographic, huanan, market, at, in, november"
230,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.25,"genome, the, covid-19, was, to, bat, and, 96.2%, sequence, that"
231,"Bats are natural hosts of many of the known  

coronaviruses","Bats have been reported as being the rich source of 

coronaviruses",0.25,"bats, of, the, coronaviruses"
232,COVID-19 is a zoonotic virus,COVID-19 is a potential zoonotic disease,0.25,"a, zoonotic"
233,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.25,"bats, are, con-, sidered, the, of"
234,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.25,"the, genome, of, sars-cov-2, that, and, is, identical, to, bat"
235,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.25,"a, virus, from, to, is, called"
236,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.25,"virus, is, from, to, a, called"
237,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.25,"of, sars-cov-2, to, species, be, through, it, is, humans, and, between, by"
238,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.25,"of, covid-19, virus, revealed, that, to, the, bat, and"
239,"Bats have been reported as being the rich source of 

coronaviruses","Bats are natural hosts of many of the known  

coronaviruses",0.25,"bats, the, of, coronaviruses"
240,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.25,"phylogenetic, analysis, shows, that, sars-cov-2, the, of, and, pangolin-cov"
241,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.25,"is, between, humans, and, it, of, sars-cov-2, to, through, species, be, by"
242,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.25,"the, progenitor, for, sars, and, viruses"
243,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.25,"bats, the, most, likely, reservoir, sars-cov-2, as, to, bat"
244,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.25,"the, for, progenitor, viruses, sars, and"
245,Bats are hosts of many coronaviruses,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.25,"are, of, many, coronaviruses"
246,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",Bats are hosts of many coronaviruses,0.25,"coronaviruses, are, of, many"
247,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.25,"and, revealed, that, the, covid-19, virus, to, of, bat"
248,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.25,"based, on, the, results, that, bats, or, pangolins, be, hosts, for"
249,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.25,"the, bats, most, likely, to, as, reservoir, sars-cov-2, bat"
250,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.25,"was, found, genome, sequence, of, 96.2%, to, a, bat, ratg13,"
251,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.25,"the, results, of, clustering, show, that, sars-cov-2, form, a, with"
252,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.25,"sars-cov-2, bat, cov, ratg13, pangolin, is, than"
253,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.25,"results, that, bats, or, pangolins, be, the, hosts, for, based, on"
254,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.25,"the, that, sars-cov-2, are, more, cluster, with, bat, cov, ratg13, than"
255,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.25,"this, that, bats, the, more, likely, of, sars-cov-2"
256,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.25,"in, viruses, and, sars-cov-2, bat, cov, ratg13, guangdong, pangolin, this, that, the, between, is, (or"
257,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.25,"this, is, sars-cov-2, and, bat, cov, ratg13, (or, guangdong, pangolin, the, between, viruses, that, in"
258,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.25,"the, sars-cov-2, bat, cov, ratg13, guangdong, pangolin, is, which, same"
259,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.25,"bat, cov, ratg13, is, sars-cov-2, than, pangolin"
260,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.25,"sars-cov-2, is, the, same, bat, cov, ratg13, guangdong, pangolin, which"
261,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.25,"that, the, of, sars-cov-2, this, more, likely, bats"
262,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.25,"the, of, that, sars-cov-2, are, to, a, cov, genome, pangolin"
263,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.25,"results, of, the, clustering, show, that, sars-cov-2, form, a, with"
264,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.25,"bat, cov, ratg13, the, cluster, with, sars-cov-2, that, are, more, than"
265,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.25,"that, sars-cov-2, genome, are, to, pangolin, cov, a, the, of"
266,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.25,"the, to, 100%, identical, sars-cov-2, and"
267,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.25,"phylogenetic, analysis, of, the, shows, that, pangolin-cov, and, sars-cov-2"
268,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.25,"the, sars-cov-2, 100%, identical, and, to"
269,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.25,"this, finding, suggests, the, pangolin, for"
270,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.25,"this, finding, suggests, pangolin, the, for"
271,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.244897959,"the, of, this, that, sars-cov-2, is, a, virus, has, been, in, for"
272,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.244897959,"the, covid-19, pandemic, is, result, of, sars-cov-2, or, a, research-related, virus, nature."
273,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.244897959,"is, sars-cov-2, a, the, covid-19, pandemic, result, of, research-related, virus, or, nature."
274,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.244897959,"in, the, of, virus, for, is, that, sars-cov-2, has, been, this, a"
275,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.243243243,"the, comparative, analysis, by, that, sars-cov-2, originated, and, a"
276,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.243243243,"a, comparative, analysis, that, sars-cov-2, originated, by, the, and"
277,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.243243243,"of, analysis, that, the, virus, to, bat, sars-like, and"
278,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.243243243,"analysis, of, virus, that, to, the, bat, sars-like, and"
279,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.242424242,"t, is, that, the, of, sequence, identity, to"
280,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.242424242,"the, sars-cov-2, genome, was, to, 96.2%, bat, cov"
281,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.242424242,"of, the, sars-cov-2, genome, with, that, sars-cov, and"
282,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.242424242,"sars-cov-2, and, bat, 96%, identity, to, the, of"
283,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.242424242,"t, that, the, sequence, of, is, to, identity"
284,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.242424242,"the, genome, of, sars-cov-2, with, that, sars-cov, and"
285,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.242424242,"several, species, to, sars-cov-2, were, and, in, the"
286,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.242424242,"in, species, were, to, sars-cov-2, and, the, several"
287,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.242424242,"genome, the, was, to, bat, cov, 96.2%, sars-cov-2"
288,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.242424242,"that, bats, are, the, reservoir, hosts, for, a"
289,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.242424242,"the, of, that, sars-cov-2, are, more, likely, than"
290,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.242424242,"that, are, the, more, likely, of, sars-cov-2, than"
291,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.242424242,"the, of, sars-cov-2, identity, and, 96%, to, bat"
292,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.24137931,"and, many, genetic, sequences, similar, to, sars-cov"
293,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.24137931,"many, genetic, sequences, similar, to, sars-cov, and"
294,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.24137931,"the, is, to, mers-cov, and, sars-cov, in"
295,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.24137931,"is, believed, the, and, be, of, to"
296,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.24137931,"be, the, of, sars-cov-2, and, an, animal"
297,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.24137931,"the, identity, of, sars-cov-2, is, with, and"
298,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.24137931,"the, sars-cov, and, mers-cov, is, to, in"
299,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.24137931,"is, believed, to, be, of, and, the"
300,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.24137931,"sars-cov-2, in, animal, host, zoonotic, or, transfer"
301,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.24137931,"the, of, sars-cov-2, is, same, pangolin-cov, and"
302,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.24137931,"of, cases, covid-19, with, onset, to, the, huanan, market, were, in, approximately, earliest, known"
303,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.24137931,"approximately, of, the, earliest, known, covid-19, cases, onset, in, to, were, with, huanan, market"
304,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.24137931,"sars-cov-2, in, animal, host, or, zoonotic, transfer"
305,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.24137931,"that, bats, are, the, more, likely, than"
306,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.24137931,"the, that, bats, are, more, likely, than"
307,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.24137931,"the, of, sars-cov-2, identity, with, and, is"
308,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.24137931,"of, the, pangolin-cov, and, sars-cov-2, is, same"
309,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.24137931,"sars-cov-2, be, of, an, animal, and, the"
310,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.240740741,"et, al., (2020), a, of, by, using, complete, genome, at, the, in, china"
311,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.240740741,"a, by, et, al., (2020), using, complete, genome, at, in, china, the, of"
312,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.24,"bats, are, and, the, major, of"
313,"According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.24,"to, sars-cov, is, closer, sars-like, bat"
314,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.24,"to, in, seafood, market, wuhan,, china"
315,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.24,"the, and, bats, may, be, of"
316,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.24,"bats, of, and, are, the, major"
317,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",Bats are likely reservoir hosts for SARS-CoV-2,0.24,"bats, are, likely, hosts, for, sars-cov-2"
318,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.24,"the, coronavirus, isolated, from, with, sars-cov-2"
319,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.24,"the, with, coronavirus, isolated, from, sars-cov-2"
320,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.24,"sars-cov-2, has, the, with, bat, ratg13"
321,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.24,"to, is, between, and, be, the"
322,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.24,"bats, may, be, the, of, and"
323,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.24,"sars-cov, is, closer, to, sars-like, bat"
324,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.24,"t, that, sars-cov-2, animal, species, humans"
325,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.24,"the, that, is, similar, to, sars-cov-2"
326,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","Bats are natural hosts of many of the known  

coronaviruses",0.24,"bats, are, the, natural, of, coronaviruses"
327,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.24,"the, that, sars-cov-2, is, similar, to"
328,"Bats are natural hosts of many of the known  

coronaviruses","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.24,"bats, are, natural, of, the, coronaviruses"
329,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.24,"to, seafood, market, in, wuhan,, china"
330,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.24,"the, is, to, be, between, and"
331,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.24,"t, that, sars-cov-2, species, humans, animal"
332,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.24,"the, ratg13, bat, has, with, sars-cov-2"
333,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.239130435,"the, sars-cov, of, bat, coro-, navirus, is, and, shares, identity, with"
334,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.239130435,"the, virus, has, a, about, to, with, that, coronavirus, and, bat"
335,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.239130435,"the, virus, a, coronavirus, that, has, about, with, bat, and, to"
336,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.239130435,"the, of, shares, identity, with, sars-cov, and, is, bat, coro-, navirus"
337,"An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.238095238,"of, coronaviruses, species, distributed, globally"
338,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.238095238,"coronaviruses, globally, distributed, of, species"
339,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.238095238,"bats, the, reservoirs, of, and"
340,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","with the first case being linked to  

a seafood market",0.238095238,"the, case, a, first, market"
341,"In the 

case of MERS, dromedaries were the principal host.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.238095238,"in, the, case, of, principal"
342,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.238095238,"from, a, virus, that, is"
343,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.238095238,"a, bat, virus, in, yunnan, has, genome, of, with, sars-cov-2"
344,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.238095238,"virus, that, is, from, a"
345,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.238095238,"this, that, sars-cov-2, may, in"
346,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.238095238,"sars-cov-2, are, the, sources, of"
347,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.238095238,"the, sources, of, sars-cov-2, are"
348,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.238095238,"genome, has, a, sars-cov-2, with, of, virus, bat, in, yunnan"
349,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.238095238,"bats, and, the, reservoirs, of"
350,"with the first case being linked to  

a seafood market","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.238095238,"the, first, case, a, market"
351,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.238095238,"to, are, identical, sars-cov-2, and"
352,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.238095238,"evidence, that, bats, and, pangolins, hosts, for, are, probable, sars-cov-2"
353,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.238095238,"sars-cov-2, may, that, in, this"
354,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.238095238,"evidence, that, bats, and, pangolins, are, probable, hosts, for, sars-cov-2"
355,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.238095238,"sars-cov-2, are, identical, to, and"
356,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.238095238,"to, that, sars-cov-2, has, similarity, the, complete, virus, genome,, of"
357,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.238095238,"the, that, sars-cov-2, has, of, complete, virus, genome,, similarity, to"
358,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.236842105,"found, that, sars-cov-2, genome, to, cov, a, the, of"
359,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.236842105,"evidence, the, that, a, as, to, spillover, from, humans"
360,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.236842105,"evidence, to, the, that, as, a, spillover, humans, from"
361,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.236842105,"a, available, to, that, sars-cov-2, originated, the, and, virus"
362,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.236842105,"to, available, sars-cov-2, a, virus, that, originated, and, the"
363,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.236842105,"the, from, a, market, in, wuhan,, transmitted, to, and"
364,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.236842105,"and, the, transmitted, from, to, a, market, in, wuhan,"
365,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.236842105,"the, was, reported, have, market,, that, been, in, of"
366,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.236842105,"of, the, reported, have, been, in, that, market,, was"
367,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.236842105,"found, that, the, genome, of, sars-cov-2, to, a, cov"
368,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.235294118,"the, genome, sars-cov-2, with, that, identical, to, bat"
369,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",Originating from reservoir of bat,0.235294118,"of, from, bat, reservoir"
370,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.235294118,"that, sars-cov-2, to, with, identical, genome, bat, the"
371,The FCS of SARS-CoV-2 was not bioengineered—full stop.,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.235294118,"the, of, sars-cov-2, was"
372,Originating from reservoir of bat,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.235294118,"from, reservoir, of, bat"
373,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.235294118,"is, that, the, of, similar, to, sars-cov-2, coronaviruses"
374,"Bats are the second  

largest order of mammals, with over 1,230 species.","Bats are natural hosts of many of the known  

coronaviruses",0.235294118,"bats, are, the, of"
375,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.235294118,"of, the, that, sars-cov-2, is, similar, to, coronaviruses"
376,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.235294118,"ratg13, has, the, et, of, region, homology, sars-cov-2"
377,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.235294118,"et, has, the, of, homology, ratg13, sars-cov-2, region"
378,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.235294118,"the, of, known, human, covid-19, cases, associated, with, huanan, seafood, market, in"
379,"Bats are natural hosts of many of the known  

coronaviruses","Bats are the second  

largest order of mammals, with over 1,230 species.",0.235294118,"bats, are, of, the"
380,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.235294118,"of, that, is, similar, to, the, and, sars-cov-2."
381,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.235294118,"of, the, known, human, covid-19, cases, in, associated, with, huanan, seafood, market"
382,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.235294118,"the, of, and, similar, to, sars-cov-2., is, that"
383,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.235294118,"sars-cov-2, was, the, of"
384,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.235294118,"that, sars-cov-2, the, same, bat, cov, ratg13, guangdong"
385,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.235294118,"that, the, sars-cov-2, bat, cov, ratg13, guangdong, same"
386,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.233333333,"analysis, of, the, shows, that, sars-cov-2, is"
387,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.233333333,"the, are, to, be, sars-cov-2, and, of"
388,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.233333333,"animal, and, are, the, sources, of, transmitted"
389,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.233333333,"the, of, sars-cov-2, are, and, be, to"
390,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.233333333,"the, mers-cov, and, that, in, animal, reservoirs"
391,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.233333333,"data, that, sars-cov-2, has, to, and, pangolin-cov"
392,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.233333333,"the, virus, to, and, that, origin, in"
393,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.233333333,"the, animal, that, in, and, mers-cov, reservoirs"
394,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.233333333,"the, origin, to, that, virus, in, and"
395,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.233333333,"virus, that, is, similar, to, the, and"
396,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.233333333,"the, animal, sources, of, are, and, transmitted"
397,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.233333333,"the, analysis, shows, that, sars-cov-2, is, of"
398,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.233333333,"the, virus, is, similar, to, and, that"
399,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.233333333,"sars-cov-2, is, to, bat, cov, ratg13, pangolin"
400,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.233333333,"sars-cov-2, to, bat, cov, ratg13, than, pangolin"
401,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.233333333,"bat, cov, ratg13, is, to, sars-cov-2, pangolin"
402,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.233333333,"bat, cov, ratg13, to, sars-cov-2, than, pangolin"
403,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.233333333,"data, to, has, that, sars-cov-2, pangolin-cov, and"
404,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.23255814,"genome, sequence, sars-cov-2, and, sars-cov, with, the, of, bat, in"
405,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.23255814,"to, ratg13,, which, was, previously, from, rhinolophus, affinis, in, yunnan"
406,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.23255814,"with, the, sars-cov, and, sars-cov-2, bat, in, of, genome, sequence"
407,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.23255814,"the, earliest, known, covid-19, cases, huanan, seafood, market, of, to"
408,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.23255814,"of, the, earliest, known, covid-19, cases, to, huanan, seafood, market"
409,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.23255814,"genome, sequences, patients, in, china, the, probable, bat, origin, of"
410,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.23255814,"to, ratg13,, which, was, previously, in, rhinolophus, affinis, from, yunnan"
411,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.23255814,"we, that, the, sars-cov-2, bat, cov, ratg13, is, than, same"
412,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.23255814,"bat, cov, ratg13, is, the, same, sars-cov-2, we, that, than"
413,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.23255814,"probable, bat, origin, of, genome, sequences, patients, the, in, china"
414,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.232142857,"on, the, other, hand,, by, and, that, originated, through, natural, a, laboratory, manipulation."
415,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.232142857,"on, the, other, hand,, by, that, originated, through, natural, and, a, laboratory, manipulation."
416,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.230769231,"coronaviruses, viruses, in, a, large, of"
417,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.230769231,"coronaviruses, of, a, large, viruses, in"
418,Originating from reservoir of bat,"An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.230769231,"reservoir, of, bat"
419,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.230769231,"the, sars-cov, was, frst, in, animals"
420,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.230769231,"are, and, can, be, transmitted, to"
421,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.230769231,"evidence, that, sars-cov-2, a, is, or"
422,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.230769231,"the, to, be, of, possible, intermediate"
423,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.230769231,"the, coronavirus, has, identity, with, bat"
424,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.230769231,"the, possible, intermediate, to, be, of"
425,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.230769231,"the, suspected, emerged, in, seafood, market"
426,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.230769231,"the, genome, of, coronavirus, 80%, to, previous, human, bat"
427,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.230769231,"the, genome, of, 80%, to, previous, human, coronavirus, bat"
428,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.230769231,"is, evidence, that, sars-cov-2, or, a"
429,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.230769231,"the, coronavirus, bat, has, identity, with"
430,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.230769231,"our, that, sars-cov-2, is, a, virus."
431,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.230769231,"is, the, related, to, sars-cov-2, in"
432,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.230769231,"the, banal-, similar, to, is, that"
433,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.230769231,"is, that, the, sars-cov-2, similar, to"
434,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.230769231,"that, sars-cov-2, is, part, of, the"
435,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.230769231,"the, of, to, bat, likely, bats, serve, as, reservoir"
436,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.230769231,"coronaviruses, that, related, to, sars-cov-2, in, including, and, china"
437,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.230769231,"the, that, banal-, is, similar, to"
438,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.230769231,"the, is, in, related, to, sars-cov-2"
439,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.230769231,"coronaviruses, to, that, related, sars-cov-2, in, china, and, including"
440,"natural selection in humans  

following zoonotic transfer","atural  

selection in an animal host before zoonotic  

transfer;",0.230769231,"selection, in, zoonotic"
441,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.230769231,"the, bats, likely, to, serve, as, reservoir, of, bat"
442,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.230769231,"suspected, seafood, market, in, the, emerged"
443,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.230769231,"the, covid-19, seafood, market, in, china"
444,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.230769231,"the, covid-19, in, seafood, market, china"
445,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.230769231,"of, the, that, sars-cov-2, is, part"
446,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.229508197,"the, results, of, clustering, that, sars-cov-2, are, to, cluster, with, bat, cov, ratg13, pangolin"
447,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.229508197,"with, the, results, clustering, to, that, sars-cov-2, of, bat, cov, ratg13, pangolin, are, cluster"
448,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.228571429,"of, more, than, to, sars-cov, and, in, bats"
449,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.228571429,"that, a, bat, found, genome, of, 96.2%, sars-cov-2"
450,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.228571429,"it, is, that, the, sars-cov-2, to, a, bat"
451,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.228571429,"and, that, the, 80%, identity, to, of, bat"
452,"When a virus passes from animals to humans for the first time it  

is called a spillover event.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.228571429,"a, from, animals, to, humans, the, it, spillover"
453,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.228571429,"the, a, it, to, spillover, from, animals, humans"
454,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.228571429,"the, of, 80%, identity, that, and, to, bat"
455,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.228571429,"at, seafood, market, in, wuhan, on, december, 2019"
456,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.228571429,"in, at, seafood, market, wuhan, on, december, 2019"
457,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.228571429,"found, that, genome, of, sars-cov-2, 96.2%, a, bat"
458,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.228571429,"a, virus, that, 96.2%, with, sars-cov-2, in, bat"
459,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.228571429,"the, phylogenetic, shows, that, sars-cov-2, of, and, pangolin-cov"
460,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.228571429,"zhou, et, al., (2020), of, sars-cov-2, the, in"
461,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.228571429,"that, a, bat, virus, in, 96.2%, with, sars-cov-2"
462,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.228571429,"in, was, similar, to, that, of, sars-cov-2, the"
463,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.228571429,"sars-cov, and, in, to, bats, of, more, than"
464,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.228571429,"the, of, scientific, that, sars-cov-2, is, a, virus"
465,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.228571429,"that, the, sars-cov-2, is, to, a, bat, it"
466,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.228571429,"zhou, et, al., (2020), the, of, sars-cov-2, in"
467,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.228571429,"phylogenetic, of, the, shows, that, pangolin-cov, and, sars-cov-2"
468,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.228571429,"of, scientific, the, that, sars-cov-2, is, a, virus"
469,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.228571429,"the, in, of, similar, to, that, sars-cov-2, was"
470,"bats are also important reservoir species for a great 

range of coronaviruses","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.227272727,"are, species, a, of, coronaviruses"
471,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.227272727,"are, the, natural, reservoir, of"
472,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.227272727,"sars-cov-2, a, that, is, in"
473,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.227272727,"the, that, is, similar, to"
474,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.227272727,"is, that, sars-cov-2, a, in"
475,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.227272727,"was, in, a, with, sars-, similar, to, at, the, genome"
476,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.227272727,"the, that, is, to, sars-cov-2"
477,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.227272727,"the, is, similar, to, that"
478,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","bats are also important reservoir species for a great 

range of coronaviruses",0.227272727,"coronaviruses, are, a, of, species"
479,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.227272727,"a, in, the, with, genome, was, similar, to, sars-, at"
480,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.227272727,"that, sars-cov-2, has, the, of, complete, virus, genome,, similarity, to"
481,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.225806452,"pangolin, and, coronaviruses, are, closely, related, to"
482,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.225806452,"are, the, natural, reservoir, variety, of, including"
483,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.225806452,"is, that, the, and, of, identity, to"
484,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.225806452,"analysis, of, data, the, that, sars-cov-2, a"
485,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.225806452,"recombination, and, pangolin-cov, that, the, of, sars-cov-2"
486,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.225806452,"to, the, of, be, possible, human, bat"
487,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.225806452,"the, of, identity, that, and, is, to"
488,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.225806452,"in, was, similar, to, that, of, the"
489,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.225806452,"and, are, closely, related, to, pangolin, coronaviruses"
490,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.225806452,"a, analysis, of, data, that, sars-cov-2, the"
491,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.225806452,"the, to, be, of, possible, bat, human"
492,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.225806452,"are, the, natural, reservoir, of, variety, including"
493,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.225806452,"of, the, banal, series, viruses, their, spike"
494,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.225806452,"the, banal, series, viruses, of, their, spike"
495,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.225806452,"it, is, that, a, of, sars-cov-2, through"
496,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.225806452,"it, is, that, sars-cov-2, through, of, a"
497,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.225806452,"fig., are, sars-cov-2, with, bat, cov, ratg13, cluster, this, that, the, same, is, than"
498,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.225806452,"fig., this, bat, cov, ratg13, is, the, same, cluster, with, sars-cov-2, that, are, than"
499,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.225806452,"of, that, sars-cov-2, the, recombination, pangolin-cov, and"
500,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.225806452,"in, that, the, recombination, between, and, of"
501,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.225806452,"recombination, between, and, that, in, the, of"
502,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.225806452,"in, the, that, was, similar, to, of"
503,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.225,"coronaviruses, to, are, closely, related, sars-cov-2, bat, in, and"
504,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.225,"the, of, that, sars-cov-2, to, a, bat, cov, genome"
505,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.225,"is, and, transmission, of, sars-cov-2, to, an, animal, be"
506,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.225,"the, to, that, sars-cov-2, possibly, was, transmitted, from, bats"
507,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.225,"sars-cov-2, is, to, be, of, an, animal, and, transmission"
508,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.225,"the, analysis, of, sequence, indicated, that, sars-cov-2, to, similar"
509,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.225,"of, the, sequence, analysis, indicated, that, sars-cov-2, similar, to"
510,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.225,"and, sars-cov-2, are, closely, related, to, bat, coronaviruses, in"
511,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.225,"bat, is, the, sars-cov-2, that, bats, are, hosts, for"
512,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.225,"is, that, bats, are, the, hosts, for, sars-cov-2, bat"
513,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.225,"sars-cov-2, and, bat, ratg13, pangolin, similarity, to, the, sars-cov-2."
514,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.225,"that, the, genome, of, sars-cov-2, to, a, bat, cov"
515,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.225,"to, sars-cov-2, that, from, bats, was, transmitted, possibly, the"
516,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.225,"sars-cov-2., similarity, sars-cov-2, and, bat, ratg13, pangolin, to, the"
517,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.224137931,"the, of, bats, living, in, extensive, limestone, cave, systems, southeast, asia, and, south"
518,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.224137931,"of, in, bats, living, the, extensive, limestone, cave, systems, southeast, asia, and, south"
519,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.224137931,"to, suggest, that, the, of, and, pangolins, may, have, hosts, for, are, sars-cov-2"
520,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.224137931,"suggest, that, may, have, of, to, and, pangolins, are, the, hosts, for, sars-cov-2"
521,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.222222222,"genome, a, 79.5%, sequence, identity, sars-cov-2, sars-cov, the, of, bat"
522,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.222222222,"the, genome, sequence, covid-19, virus, and, showed, was, bat, identity"
523,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.222222222,"the, sequence, of, to, sars-cov, and, mers-cov, in"
524,Bats are hosts of many coronaviruses,hese reservoirs are the bats,0.222222222,"bats, are"
525,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.222222222,"the, to, and, that, sequence, was, 96.2%, a"
526,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.222222222,"the, is, to, be, of, and"
527,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.222222222,"the, spillover, an, animal, be, of"
528,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",Bats are likely reservoir hosts for SARS-CoV-2,0.222222222,"bats, are, likely, sars-cov-2"
529,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.222222222,"the, bat, 96%, identity, with, sars-cov-2"
530,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","civet cats and raccoon dogs  

are the intermediate hosts",0.222222222,"the, are, hosts, and"
531,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","with the first case being linked to  

a seafood market",0.222222222,"the, to, seafood, market"
532,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.222222222,"the, to, bat, coronavirus, and, that, was, a"
533,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.222222222,"in, the, case, of, was, and"
534,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.222222222,"a, the, to, that, 96.2%, sequence, and, was"
535,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.222222222,"the, was, a, coronavirus, that, bat, and, to"
536,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.222222222,"the, genome, was, to, 96.2%, bat"
537,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.222222222,"the, of, covid-19, with, huanan, market, in, wuhan"
538,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.222222222,"is, that, the, virus, and, bats, be, to"
539,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.222222222,"genome, has, a, identity, and, with, the, of, virus, from, bat, (rhinolophus"
540,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.222222222,"the, sars-cov-2, has, been, to, coronavirus"
541,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.222222222,"the, sars-cov-2, identity, with, 96%, bat"
542,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.222222222,"that, by, a, recombination, of, virus, to, and, the, sars-cov-2"
543,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.222222222,"is, to, be, of, and, the"
544,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.222222222,"is, the, and, be, of, to"
545,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.222222222,"the, of, to, be, is, possible, and, between"
546,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.222222222,"bat, be, the, of, and, intermediate"
547,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.222222222,"the, of, evidence, at, that, is, a, virus"
548,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.222222222,"is, that, the, virus, and, to"
549,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.222222222,"that, the, virus, had, and, to"
550,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.222222222,"to, is, be, virus, that, bats, and, the"
551,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.222222222,"the, virus, is, to, and, that"
552,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.222222222,"the, of, patients, were, with, seafood, market, in, wuhan, china"
553,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.222222222,"coronavirus, the, has, been, to, sars-cov-2"
554,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.222222222,"has, been, the, of, human, bat"
555,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.222222222,"covs, in, and, can, to, humans"
556,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.222222222,"the, of, has, been, human, bat"
557,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.222222222,"the, sars, closely, related, to, in"
558,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.222222222,"the, virus, to, and, that, had"
559,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.222222222,"virus, genome, the, covid-19, was, bat, and, showed, sequence, identity"
560,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.222222222,"was, a, who, at, seafood, market, and, wuhan, on, december"
561,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.222222222,"the, genome, sequence, of, sars-cov-2, a, bat, 79.5%, identity, sars-cov"
562,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.222222222,"the, virus, has, a, genome, of, identity, with, from, and, bat, (rhinolophus"
563,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.222222222,"that, a, bat, virus, in, sars-cov-2"
564,"civet cats and raccoon dogs  

are the intermediate hosts","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.222222222,"and, are, the, hosts"
565,"Bats are natural hosts of many of the known  

coronaviruses","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.222222222,"are, hosts, of, the"
566,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","Bats are natural hosts of many of the known  

coronaviruses",0.222222222,"the, bats, are, of"
567,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Bats are natural hosts of many of the known  

coronaviruses",0.222222222,"the, of, are, hosts"
568,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.222222222,"that, the, pan-, golin, a, of"
569,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.222222222,"a, the, pan-, golin, that, of"
570,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.222222222,"analysis, that, the, is, sars-cov-2, a"
571,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.222222222,"the, covid-19, in, to, wuhan, seafood, december, 2019"
572,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.222222222,"be, spillover, of, an, animal, the"
573,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.222222222,"sars-cov-2, a, recombinant, between, the, and"
574,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.222222222,"sars-cov-2, a, virus, that, in, bat"
575,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","bats are also important reservoir species for a great 

range of coronaviruses",0.222222222,"bats, are, reservoir, for, a, of"
576,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.222222222,"at, with, sars-cov-2, the, amino, acid, sequence, of, s, protein"
577,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.222222222,"the, is, to, be, of, possible, between, and"
578,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.222222222,"the, sars, in, closely, related, to"
579,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.222222222,"the, closely, related, virus, to, in"
580,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.222222222,"that, are, similar, to, and, the, of, sars-cov-2."
581,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.222222222,"the, virus, closely, related, to, in"
582,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.222222222,"was, and, who, at, a, seafood, market, wuhan, on, december"
583,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.222222222,"the, sars-cov, and, mers-cov, to, in, of, sequence"
584,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.222222222,"covid-19, to, the, seafood, in, wuhan, december, 2019"
585,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.222222222,"covs, can, to, in, humans, and"
586,hese reservoirs are the bats,Bats are hosts of many coronaviruses,0.222222222,"are, bats"
587,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.222222222,"of, covid-19, in, the, huanan, market, with, wuhan"
588,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.222222222,"the, patients, with, wuhan, in, china, seafood, market, were, of"
589,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.222222222,"s, protein, at, the, sequence, of, amino, acid, with, sars-cov-2"
590,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.222222222,"the, genome, to, bat, was, 96.2%"
591,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.222222222,"the, that, bats, are, likely, hosts, for, sars-cov-2"
592,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.222222222,"a, of, to, that, sars-cov-2, by, the, recombination, and, virus"
593,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.222222222,"this, that, bats, are, the, more, sars-cov-2, than"
594,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.222222222,"that, bats, are, the, likely, hosts, for, sars-cov-2"
595,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.222222222,"this, the, sars-cov-2, that, bats, are, more, than"
596,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.222222222,"the, of, and, are, similar, to, sars-cov-2., that"
597,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.222222222,"bat-sl-cov-2, with, and, pangolin-cov, similarity, sars-cov-2"
598,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.222222222,"is, the, with, and, pangolin-cov, sars-cov-2"
599,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.222222222,"sars-cov-2, similarity, bat-sl-cov-2, and, pangolin-cov, with"
600,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.222222222,"the, sars-cov-2, is, with, pangolin-cov, and"
601,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.222222222,"the, be, of, intermediate, bat, and"
602,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.222222222,"the, sars-cov-2, a, recombinant, between, and"
603,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.222222222,"is, evidence, at, that, the, virus, of, a"
604,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.222222222,"analysis, the, that, sars-cov-2, is, a"
605,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.220338983,"of, that, the, a, ace2, animal, species, as, intermediate, hosts, or, models, for"
606,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.220338983,"ace2, a, of, animal, species, that, the, as, models, or, intermediate, hosts, for"
607,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.22,"are, a, other, closely, related, coronaviruses, to, in, sars-cov-2, bat, and"
608,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.22,"the, of, virus, it, is, to, that, has, been, and, a"
609,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.22,"the, is, that, virus, to, a, of, and, it, has, been"
610,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.22,"and, sars-cov-2, are, closely, related, to, bat, coronaviruses, in, a, other"
611,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.219512195,"a, coronavirus, from, the, pangolin, has, to, 99%, with"
612,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.219512195,"the, has, a, to, 99%, with, coronavirus, from, pangolin"
613,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.219512195,"the, at, huanan, seafood, market, to, wuhan, on, december"
614,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.219512195,"to, at, the, huanan, seafood, market, wuhan, on, december"
615,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.219512195,"that, natural, the, most, scenario, of, origin, and, is"
616,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.219512195,"and, that, natural, origin, of, the, is, most, scenario"
617,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.219512195,"the, sars-cov-2, bat, cov, ratg13, guangdong, pangolin, is, same"
618,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.219512195,"bat, cov, the, same, origin, sars-cov-2, with, ratg13, guangdong"
619,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.219512195,"sars-cov-2, is, the, same, bat, cov, ratg13, guangdong, pangolin"
620,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.219512195,"sars-cov-2, the, same, origin, with, bat, cov, ratg13, guangdong"
621,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.21875,"the, to, be, sars-cov-2, and, of, transmission"
622,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.21875,"available, evidence, that, sars-cov-2, a, natural, origin"
623,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.21875,"sars-cov-2, to, be, of, and, the, transmission"
624,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.21875,"a, coronavirus, the, has, to, similarity, with"
625,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.21875,"virus, that, is, transmitted, from, to, a"
626,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.21875,"the, a, coronavirus, has, with, similarity, to"
627,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.21875,"the, of, bat, ,, it, that, reservoir"
628,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.21875,"to, is, a, virus, that, from, transmitted"
629,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.21875,"evidence, available, that, sars-cov-2, a, natural, origin"
630,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.21875,"analysis, of, the, sequence, that, sars-cov-2, is"
631,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.21875,"this, that, sars-cov-2, is, a, virus, in"
632,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.21875,"bats, are, the, most, likely, hosts, to"
633,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.21875,"that, a, strain, in, genome, of, with"
634,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.21875,"the, of, similar, to, that, sars-, cov-2"
635,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.21875,"the, of, natural, origin, a, as, and"
636,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.21875,"there, is, no, that, or, of, the"
637,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.21875,"a, strain, in, with, genome, that, of"
638,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.21875,"to, is, 52, 96.8%, similar, sars-cov-2, the"
639,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.21875,"of, the, sequence, analysis, that, sars-cov-2, is"
640,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.21875,"the, 52, is, 96.8%, similar, to, sars-cov-2"
641,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.21875,"the, that, similar, to, of, sars-, cov-2"
642,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.21875,"that, the, rbd, of, banal-52, to, sars-cov-2."
643,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.21875,"the, of, banal-52, to, rbd, sars-cov-2., that"
644,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.21875,",, it, that, the, of, bat, reservoir"
645,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.21875,"there, is, no, that, the, of, or"
646,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.21875,"the, natural, origin, of, as, a, and"
647,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.21875,"bats, are, to, the, most, likely, hosts"
648,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.21875,"is, sars-cov-2, bat, cov, ratg13, pangolin, to"
649,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.21875,"sars-cov-2, a, virus, that, is, in, this"
650,"Bats are natural hosts of many of the known  

coronaviruses","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.217391304,"bats, are, of, the, known"
651,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.217391304,"are, and, the, natural, of"
652,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.217391304,"the, be, of, hosts, and"
653,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.217391304,"are, the, natural, of, and"
654,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.217391304,"the, of, are, bats, and"
655,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.217391304,"ratg13,, from, rhinolophus, affinis, is, identical, to, in, the, which"
656,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",Bats are likely reservoir hosts for SARS-CoV-2,0.217391304,"bats, are, likely, hosts, for"
657,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",Bats are likely reservoir hosts for SARS-CoV-2,0.217391304,"bats, are, reservoir, hosts, for"
658,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.217391304,"bats, are, and, the, of"
659,"a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.217391304,"a, coronavirus, similarity, with, sars-cov-2"
660,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.217391304,"be, the, hosts, of, and"
661,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.217391304,"virus, that, is, animal, to"
662,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.217391304,"virus, is, to, that, animal"
663,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.217391304,"a, zoonotic, from, an, to"
664,"Bats are natural hosts of many of the known  

coronaviruses","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.217391304,"bats, are, hosts, of, the"
665,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.217391304,"to, sars-, the, of, bats, pangolins, may, hosts, cov-2,, are"
666,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Bats are natural hosts of many of the known  

coronaviruses",0.217391304,"bats, of, are, known, the"
667,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Bats are natural hosts of many of the known  

coronaviruses",0.217391304,"bats, are, the, hosts, of"
668,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.217391304,"from, an, to, a, zoonotic"
669,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.217391304,"the, of, first, covid-19, associated, with, huanan, seafood, market, in"
670,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.217391304,"is, identical, the, to, ratg13,, which, in, rhinolophus, affinis, from"
671,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.217391304,"this, again, the, origin, of"
672,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.217391304,"this, that, sars-cov-2, bats, pa"
673,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.217391304,"this, that, bats, sars-cov-2, pa"
674,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.217391304,"bats, are, to, the, hosts, of, sars-, cov-2,, pangolins, may"
675,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.217391304,"bat-sl-cov, is, the, of, sars-cov-2"
676,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.217391304,"the, of, sars-cov-2, is, bat-sl-cov"
677,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.216666667,"a, of, the, from, lineage, this, that, sars-cov-2, are, at, least, two, viruses"
678,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.216666667,"a, viruses, are, at, least, two, that, the, of, sars-cov-2, from, this, lineage"
679,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.216666667,"the, between, earliest, known, covid-19, cases, and, huanan, seafood, of, suggesting, a, 19"
680,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.216666667,"a, of, the, 19, covid-19, cases, between, and, huanan, seafood, suggesting, earliest, known"
681,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.216216216,"of, that, it, is, to, the, bat, was"
682,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.216216216,"is, the, bat, known, to, sequence, in, of"
683,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.216216216,"the, to, and, that, its, origin, animal, reservoirs"
684,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.216216216,"to, the, sars-cov-2, as, of, spillover, humans, from"
685,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.216216216,"to, the, of, sars-cov-2, from, as, spillover, humans"
686,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.216216216,"that, sars-cov-2, to, a, hypothesis, the, origin, of"
687,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.216216216,"has, identity, sars-cov-2, with, the, isolated, from, bat"
688,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.216216216,"of, a, analysis, that, the, virus, to, and"
689,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.216216216,"the, origin, its, to, that, and, animal, reservoirs"
690,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.216216216,"is, that, bats, the, reservoir, sars-cov-2, to, bat"
691,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.216216216,"the, isolated, from, bat, has, identity, with, sars-cov-2"
692,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.216216216,"of, the, two, and, that, sars-cov-2, a, with"
693,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.216216216,"a, single, amino, acid, change, the, to, ace2"
694,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.216216216,"to, a, single, amino, acid, change, the, ace2"
695,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.216216216,"samples, from, the, market, that, of, dogs, in"
696,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.216216216,"the, of, dogs, in, samples, from, market, that"
697,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.216216216,"the, banal, of, closely, related, to, measured, by"
698,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.216216216,"the, banal, closely, related, to, measured, by, of"
699,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.216216216,"of, that, it, is, to, the, bat, for"
700,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.216216216,"rbd, of, sars-cov-2, was, also, to, the, in"
701,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.216216216,"was, that, the, of, is, to, bat, it"
702,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.216216216,"the, of, to, bat, it, is, that, for"
703,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.216216216,"the, in, of, rbd, to, sars-cov-2, was, also"
704,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.216216216,"that, sars-cov-2, is, to, bat, bats, the, reservoir"
705,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.216216216,"a, analysis, of, to, that, the, and, virus"
706,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.216216216,"a, of, the, sars-cov-2, with, that, and, two"
707,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.216216216,"to, the, hypothesis, that, sars-cov-2, a, of, origin"
708,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.216216216,"the, known, is, to, bat, in, of, sequence"
709,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.215686275,"by, related, banal, which, similar, to, sars-cov-2, at, the, whole, genome"
710,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.215686275,"related, to, by, banal, which, similar, sars-cov-2, at, the, whole, genome"
711,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.215686275,"the, is, of, known, covid-19, cases, huanan, seafood, market, and, one"
712,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.215686275,"the, known, covid-19, cases, and, huanan, seafood, market, is, one, of"
713,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.215686275,"seafood, market, in, wuhan, city,, hubei, province,, china, the, of, were"
714,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.215686275,"the, of, were, seafood, market, in, wuhan, city,, hubei, province,, china"
715,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.215189873,"in, with, the, fig., and, that, sars-cov-2, is, bat, cov, ratg13, guangdong, pangolin, are, 16, representatives, cluster"
716,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.215189873,"in, fig., are, and, 16, sars-cov-2, representatives, with, bat, cov, ratg13, guangdong, pangolin, cluster, that, the, is"
717,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.214285714,"of, globally, distributed, species, are, animal"
718,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.214285714,"are, globally, distributed, of, animal, species"
719,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.214285714,"the, sars-cov-2, and, of, genome, sequence, is, to, bat"
720,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.214285714,"sars-cov-2, be, a, the, and, an"
721,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.214285714,"bats, the, hosts, of, and, mers-cov"
722,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.214285714,"analysis, of, the, that, sars-cov-2, is"
723,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.214285714,"the, and, bats, be, of, to"
724,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.214285714,"be, the, of, sars-cov-2, and, animal"
725,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.214285714,"in, from, of, bats, to, support, sars-cov-2, the, humans"
726,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.214285714,"that, the, from, a, market, animals, in, to, humans"
727,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.214285714,"that, the, virus, originated, bats, and, transmitted, to, intermediate"
728,Bats are hosts of many coronaviruses,"Bats have been reported as being the rich source of 

coronaviruses",0.214285714,"bats, of, coronaviruses"
729,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.214285714,"sars-cov-2, bat, ratg13, 96%, identity, the"
730,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.214285714,"to, be, the, hosts, of, intermediate"
731,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.214285714,"the, to, in, market, wuhan,, china"
732,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.214285714,"there, is, no, that, of, the"
733,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.214285714,"the, of, bats, and, be, to"
734,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.214285714,"bats, to, is, and, be, the"
735,Bats are hosts of many coronaviruses,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.214285714,"bats, are, of"
736,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.214285714,"the, and, sars-cov-2, is, to, bat, of, genome, sequence"
737,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.214285714,"is, also, from, in, the, of"
738,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.214285714,"is, the, closely, related, to, in"
739,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.214285714,"suggests, that, is, sars-cov-2, a, or"
740,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.214285714,"the, that, in, a, to, from, animals, humans, market"
741,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.214285714,"the, to, be, of, intermediate, hosts"
742,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.214285714,"the, analysis, that, sars-cov-2, is, of"
743,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.214285714,"rbd, of, sars-cov-2, was, to, which, the, its, in"
744,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","bats are also important reservoir species for a great 

range of coronaviruses",0.214285714,"bats, are, reservoir, for, of, coronaviruses"
745,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.214285714,"the, sars-cov-2, to, humans, from, bats, in, support, of"
746,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.214285714,"the, of, in, is, also, from"
747,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.214285714,"the, in, is, closely, related, to"
748,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.214285714,"has, sars-cov-2, in, animal, before, humans"
749,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.214285714,"to, virus, that, originated, bats, and, transmitted, the, intermediate"
750,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.214285714,"the, to, market, in, wuhan,, china"
751,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.214285714,"there, is, no, that, the, of"
752,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.214285714,"is, the, and, bats, be, to"
753,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.214285714,"sars-cov-2, has, in, animal, before, humans"
754,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.214285714,"sars-cov-2, to, identical, genome, bat, the"
755,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",SARS-CoV-2 was created from SARS-CoV-2,0.214285714,"sars-cov-2, was, from"
756,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.214285714,"its, in, the, of, which, sars-cov-2, was, to, rbd"
757,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.214285714,"that, sars-cov-2, is, very, likely, to"
758,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.214285714,"bat-sl-cov-2, the, and, pangolin-cov, for, sars-cov-2"
759,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.214285714,"for, bat-sl-cov-2, and, pangolin-cov, the, sars-cov-2"
760,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.214285714,"is, that, likely, sars-cov-2, very, to"
761,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.214285714,"the, animal, of, sars-cov-2, and, be"
762,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.214285714,"sars-cov-2, be, a, an, and, the"
763,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.214285714,"the, ratg13, bat, 96%, identity, sars-cov-2"
764,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.214285714,"suggests, that, sars-cov-2, a, is, or"
765,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.213740458,"at, infected, to, a, palm, as, civets, sampled, from, animal, in, chinese, tested, for, the, virus, antibodies., by, collected, markets, sars, cases,, live, were, of, and, also, species"
766,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.213740458,"in, the, sars, cases,, live, animal, markets, of, from, sampled, palm, civets, tested, for, as, chinese, at, also, antibodies., virus, collected, to, species, were, infected, by, a, and"
767,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.212765957,"the, is, of, with, huanan, market, and, lineage, in, at"
768,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.212765957,"genetic, that, the, in, to, humans, from, animals, a, market"
769,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.212765957,"the, genome, sequence, coronavirus, that, was, very, to, bat, and"
770,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.212765957,"and, that, the, covid-19, virus, has, identity, to, of, bat"
771,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.212765957,"genetic, the, that, in, a, to, from, animals, humans, market"
772,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.212765957,"the, genome, to, bat, coronavirus, and, that, sequence, was, very"
773,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.212765957,"the, virus, covid-19, has, of, to, identity, that, and, bat"
774,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.212765957,"is, with, and, of, lineage, at, the, huanan, market, in"
775,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.212121212,"the, are, known, to, be, and, of"
776,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.212121212,"the, genome, of, sars-cov-2, identical, to, bat"
777,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.212121212,"the, of, sars-cov-2, is, identical, to, sars-cov"
778,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.212121212,"the, of, sars-cov-2, shares, identity, with, sars-cov"
779,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.212121212,"a, from, the, coronavirus, sequence, with, sars-cov-2"
780,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.212121212,"sars-cov-2, the, of, shares, identity, with, sars-cov"
781,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.212121212,"of, and, are, known, to, be, the"
782,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.212121212,"is, at, the, huanan, market, in, 2019"
783,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.212121212,"a, coronavirus, the, genome, that, was, to"
784,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.212121212,"that, sars-cov-2, is, to, be, originated, from"
785,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.212121212,"of, virus, that, is, to, the, and"
786,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.212121212,"the, to, for, a, from, animals, is"
787,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.212121212,"that, animal, has, not, origin, is, a"
788,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.212121212,"in, a, was, first, patients, and, market"
789,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.212121212,"the, sequence, with, a, coronavirus, from, sars-cov-2"
790,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.212121212,"the, genome, to, coronavirus, that, was, a"
791,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.212121212,"that, has, a, animal, origin, is, not"
792,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.212121212,"the, of, and, is, that, sars-, cov-2"
793,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.212121212,"the, most, closely, related, to, sars-cov-2, in"
794,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.212121212,"of, the, sars-, cov-2, that, and, is"
795,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.212121212,"the, to, most, closely, related, sars-cov-2, in"
796,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.212121212,"indicates, that, the, covid-19, and, wild, animals"
797,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.212121212,"is, that, the, virus, and, of, to"
798,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.212121212,"was, first, and, in, patients, a, market"
799,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.212121212,"the, indicates, that, covid-19, and, wild, animals"
800,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.212121212,"a, from, animals, to, for, the, is"
801,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.212121212,"the, that, sars-cov-2, bat-sl-cov-2, of, and, pangolin-cov"
802,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.212121212,"the, sars-cov-2, with, bat-sl-cov-2, and, similarity, pangolin-cov"
803,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.212121212,"bat-sl-cov-2, and, pangolin-cov, that, the, of, sars-cov-2"
804,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.212121212,"bat-sl-cov-2, the, with, and, pangolin-cov, similarity, sars-cov-2"
805,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.212121212,"to, sars-cov-2, is, be, that, originated, from"
806,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.211111111,"of, cases, covid-19, with, had, a, to, early, wuhan, area, and, the, huanan, market, were, only, exposed, in, known"
807,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.211111111,"the, huanan, market, only, wuhan, area, in, of, cases, were, exposed, to, and, with, a, early, known, covid-19, had"
808,"bats are also important reservoir species for a great 

range of coronaviruses","An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.210526316,"reservoir, species, of, coronaviruses"
809,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.210526316,"a, is, the, to, that, 96.2%, sequence, was"
810,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.210526316,"a, sequence, that, 96.2%, identity, the, sars-cov-2, bat"
811,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.210526316,"the, animal, of, sars-cov-2, and, can, be, to"
812,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.210526316,"was, that, the, sequence, is, 96.2%, to, a"
813,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.210526316,"the, virus, was, a, that, and, similarity, to"
814,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.210526316,"discovered, a, virus, sequence, that, 96.2%, the, in"
815,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.210526316,"covid-19, is, to, the, market, in, wuhan, on"
816,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.210526316,"the, of, that, sars-cov-2, to, with, bat, genome"
817,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.210526316,"the, of, can, be, to, and, animal, sars-cov-2"
818,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.210526316,"a, the, to, that, similarity, virus, and, was"
819,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.210526316,"the, that, has, with, virus, and, similarity, to"
820,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.210526316,"is, that, bats, the, sars-cov-2, as, to, a"
821,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.210526316,"analysis, that, the, virus, originated, and, to, of"
822,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.210526316,"to, recombination, the, of, pangolin-cov, by, a, virus"
823,"bats are also important reservoir species for a great 

range of coronaviruses","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.210526316,"bats, are, reservoir, of"
824,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.210526316,"the, genetic, similarity, sars-cov-2, and, beta, of, et, al.,, sequence, that, bat"
825,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.210526316,"sequence, beta, bat, that, the, of, sars-cov-2, et, al.,, and, genetic, similarity"
826,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.210526316,"a, analysis, the, sars-cov-2, genome, that, revealed, and"
827,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.210526316,"the, genome, analysis, revealed, that, sars-cov-2, and, a"
828,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.210526316,"on, the, to, market, in, wuhan, is, covid-19"
829,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.210526316,"that, 2, been, a, of, virus, with, to, and, the, for, sars-cov-2"
830,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.210526316,"has, genome, 96.2%, with, bat, that, sars-cov-2, a"
831,"An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally","bats are also important reservoir species for a great 

range of coronaviruses",0.210526316,"reservoir, of, coronaviruses, species"
832,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.210526316,"to, that, the, of, sars-, cov-2, and, is"
833,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.210526316,"that, the, sequence, sars-cov-2, 96.2%, a, bat, identity"
834,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.210526316,"a, the, that, discovered, in, 96.2%, sequence, virus"
835,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.210526316,"analysis, of, to, that, originated, the, and, virus"
836,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.210526316,"that, a, bat, has, genome, 96.2%, with, sars-cov-2"
837,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.210526316,"bat, cov, to, sars-cov-2"
838,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.210526316,"the, of, and, to, is, that, sars-, cov-2"
839,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.210526316,"to, sars-cov-2, is, a, that, bats, the, as"
840,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.210526316,"the, that, sars-cov-2, are, likely, to, a, bat"
841,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.210526316,"the, of, virus, for, 2, to, that, sars-cov-2, been, with, and, a"
842,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.210526316,"sars-cov-2, to, bat, cov"
843,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.210526316,"we, that, sars-cov-2, the, bat, cov, ratg13, guangdong"
844,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.210526316,"we, sars-cov-2, bat, cov, ratg13, guangdong, the, that"
845,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.210526316,"the, genome, of, sars-cov-2, with, that, to, bat"
846,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.210526316,"that, are, the, likely, sars-cov-2, to, a, bat"
847,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.210526316,"the, virus, that, has, with, and, similarity, to"
848,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.210526316,"a, of, to, by, the, recombination, pangolin-cov, virus"
849,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.209677419,"an, intermediate, host, and, humans, was, found, in, closely, related, the, palm, civet"
850,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.209677419,"in, the, palm, an, intermediate, host, was, found, humans, and, civet, closely, related"
851,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.209302326,"several, have, the, sars-cov-2, genome, identical, to, that, bat"
852,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.209302326,"the, to, that, 96.2%, sequence, human, virus, and, was"
853,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.209302326,"virus, the, was, to, and, 96.2%, sequence, that, human"
854,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.209302326,"genome, identity, sars-cov-2, and, sars-cov, with, the, of, bat"
855,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.209302326,"the, infected, in, may, have, market, animals, or, source"
856,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.209302326,"source, infected, or, animals, in, the, market, may, have"
857,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.209302326,"several, have, that, sars-cov-2, to, identical, genome, bat, the"
858,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.209302326,"the, genome, of, sars-cov-2, identity, with, sars-cov, and, bat"
859,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.209302326,"the, covid-19, is, of, a, natural, zoonotic, spillover, to"
860,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.209302326,"the, horseshoe, bats, species, most, likely, of, (rhinolophus, and"
861,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.209302326,"the, most, likely, species, of, horseshoe, bats, (rhinolophus, and"
862,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.209302326,"the, covid-19, is, of, natural, zoonotic, spillover, to, a"
863,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.209302326,"the, sars-cov-2, likely, to, with, bat, cov, ratg13, pangolin"
864,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.209302326,"that, the, of, bats, are, more, origin, sars-cov-2, than"
865,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.209302326,"that, bats, are, the, more, origin, of, sars-cov-2, than"
866,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.209302326,"sars-cov-2, to, likely, the, with, bat, cov, ratg13, pangolin"
867,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.209150327,"as, a, of, the, shenzhen, market, public, health, investigators, palm, civets, at, animal, and, live, markets, were, by, in, to, sars, evidence, infected, for, found, that, from, tested, positive, collected, sampled, located"
868,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.209150327,"in, the, sars, public, health, investigators, live, animal, markets, of, located, from, found, that, sampled, palm, civets, tested, positive, for, as, at, market, collected, to, shenzhen, were, infected, by, a, and, evidence"
869,"bats are also important reservoir species for a great 

range of coronaviruses","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.208333333,"bats, reservoir, a, of, coronaviruses"
870,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.208333333,"virus, is, to, its, in"
871,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.208333333,"of, genomic, sars-cov-2, similar, to"
872,"with the first case being linked to  

a seafood market","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.208333333,"linked, to, a, seafood, market"
873,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.208333333,"the, of, bats, and, be"
874,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.208333333,"bats, be, the, of, and"
875,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.208333333,"the, to, are, sars-cov-2, and"
876,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.208333333,"clustering, of, cases, in, around, the, huanan, market, with, early"
877,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.208333333,"wiv, that, is, in, sars-cov-2"
878,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.208333333,"that, sars-cov-2, is, a, or"
879,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.208333333,"the, of, with, clustering, early, cases, around, huanan, market, in"
880,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Bats have been reported as being the rich source of 

coronaviruses",0.208333333,"of, the, reported, have, been"
881,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.208333333,"sars-cov-2, has, a, similarity, to"
882,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.208333333,"virus, is, to, in, its"
883,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.208333333,"genome, alignment, sequence, identity, and, with, the, of, virus, bat"
884,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.208333333,"genomic, of, sars-cov-2, similar, to"
885,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.208333333,"alignment, of, the, genome, sequence, virus, and, with, bat, identity"
886,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.208333333,"in, the, rbd, of, to, sars-cov-2, that, pangolin, which, virus"
887,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.208333333,"a, has, to, similarity, sars-cov-2"
888,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.208333333,"the, intermediate, host, for, sars-cov-2"
889,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.208333333,"is, that, wiv, sars-cov-2, in"
890,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","bats are also important reservoir species for a great 

range of coronaviruses",0.208333333,"coronaviruses, of, a, reservoir, bats"
891,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.208333333,"are, closely, related, coronaviruses, to, in, sars-cov-2, the, bat, and"
892,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.208333333,"the, coronaviruses, to, are, closely, related, sars-cov-2, bat, in, and"
893,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.208333333,"is, that, sars-cov-2, or, a"
894,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.208333333,"is, that, sars-cov-2, laboratory, a"
895,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.208333333,"that, sars-cov-2, is, a, laboratory"
896,"Bats have been reported as being the rich source of 

coronaviruses","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.208333333,"have, been, reported, the, of"
897,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.208333333,"that, sars-cov-2, are, similar, to, pangolin, and, a, the, of"
898,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.208333333,"the, that, sars-cov-2, is, of"
899,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.208333333,"we, that, the, of, sars-cov-2"
900,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.208333333,"that, a, of, pangolin, similar, to, and, are, the, sars-cov-2"
901,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.208333333,"we, that, sars-cov-2, of, the"
902,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.208333333,"the, sars-cov-2, are, and, to"
903,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.208333333,"in, the, of, which, that, sars-cov-2, to, rbd, pangolin, virus"
904,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.208333333,"intermediate, host, for, sars-cov-2, the"
905,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.208333333,"of, the, that, sars-cov-2, is"
906,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.20754717,"a, by, et, al., from, was, at, market, the, virus, of"
907,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.20754717,"the, not, to, this, it, that, has, been, in, with, of"
908,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.20754717,"in, the, of, it, not, to, that, has, been, with, this"
909,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.20754717,"of, a, virus, at, the, market, was, by, et, al., from"
910,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.206896552,"sars-cov-2, is, to, in, whole, genome"
911,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.206896552,"is, to, sars-cov-2, in, whole, genome"
912,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.206896552,"the, animal, believed, to, be, of"
913,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.206896552,"the, of, sars-cov-2, is, and, to"
914,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.206896552,"the, is, to, of, bat, and"
915,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.206896552,"the, is, to, and, sars-cov, that"
916,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.206896552,"bats, are, to, be, the, of"
917,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.206896552,"sars-cov-2, and, to, bats, the, of"
918,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.206896552,"that, there, is, evidence, in, a"
919,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.206896552,"there, is, evidence, that, a, in"
920,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.206896552,"believed, to, be, of, animal, the"
921,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.206896552,"be, the, host, of, animal, intermediate"
922,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.206896552,"a, sars-cov-2, 99%, similarity, with, the"
923,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.206896552,"from, the, has, coronavirus, with, sars-cov-2"
924,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.206896552,"the, of, and, is, to, bat"
925,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.206896552,"of, the, that, is, a, virus"
926,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.206896552,"the, that, sars-cov, and, is, to"
927,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.206896552,"the, and, similar, to, is, that"
928,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.206896552,"and, to, the, zoonotic, of, virus"
929,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.206896552,"the, of, are, bats, be, to"
930,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.206896552,"coronaviruses, to, are, closely, related, and"
931,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.206896552,"the, of, sars-cov-2, bats, and, to"
932,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.206896552,"the, reservoirs, for, viruses, of, and"
933,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.206896552,"a, the, 99%, similarity, with, sars-cov-2"
934,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.206896552,"bat, with, similarity, sars-cov-2, found, in"
935,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.206896552,"is, that, the, similar, to, sars-cov-2"
936,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.206896552,"bat, found, in, similarity, with, sars-cov-2"
937,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.206896552,"the, for, viruses, reservoirs, and, of"
938,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.206896552,"and, coronaviruses, are, closely, related, to"
939,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.206896552,"are, a, other, closely, related, to, in, coronaviruses,, with, sars-cov-2, the, and"
940,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.206896552,"the, is, similar, to, and, that"
941,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.206896552,"in, a, with, other, closely, related, coronaviruses,, and, are, to, sars-cov-2, the"
942,"t some virus detected in pangolins 

were capable of infecting humans.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.206896552,"t, virus, in, pangolins, of, humans."
943,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","t some virus detected in pangolins 

were capable of infecting humans.",0.206896552,"in, pangolins, of, virus, humans., t"
944,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.206896552,"is, that, the, virus, of, a"
945,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.206896552,"the, virus, zoonotic, and, of, to"
946,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",Genetic evidence suggesting otherwise is yet to be presented.,0.206896552,"to, evidence, is, yet, be, presented."
947,Genetic evidence suggesting otherwise is yet to be presented.,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.206896552,"evidence, is, yet, to, be, presented."
948,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.206896552,"that, bats, are, hosts, for, sars-cov-2"
949,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.206896552,"that, bats, are, the, likely, sars-cov-2"
950,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.206896552,"sars-cov-2, showed, highest, with, bat-sl-cov-2, pangolin-cov"
951,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.206896552,"sars-cov-2, is, to, of, and, the"
952,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.206896552,"the, of, sars-cov-2, identity, with, pangolin-cov"
953,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.206896552,"showed, sars-cov-2, highest, bat-sl-cov-2, pangolin-cov, with"
954,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.206896552,"the, identity, of, sars-cov-2, with, pangolin-cov"
955,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.206896552,"the, intermediate, host, animal, be, of"
956,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.205882353,"the, and, are, similar, to, sars-, cov-2"
957,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.205882353,"to, the, sequence, a, bats,, is, considered"
958,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.205882353,"is, that, the, virus, and, sequence, to"
959,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.205882353,"and, to, a, market, in, wuhan,, china"
960,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.205882353,"a, is, the, to, bats,, sequence, considered"
961,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.205882353,"the, pangolin, is, to, be, intermediate, and"
962,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.205882353,"analysis, of, the, that, pangolin-cov, and, sars-cov-2"
963,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.205882353,"to, is, be, and, the, pangolin, intermediate"
964,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.205882353,"the, between, and, is, one, of, to"
965,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.205882353,"to, a, and, market, in, wuhan,, china"
966,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.205882353,"is, the, to, that, sequence, virus, and"
967,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.205882353,"and, that, the, virus, identity, to, of"
968,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.205882353,"the, sequence, of, identity, to, and, bats"
969,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.205882353,"analysis, of, that, is, similar, to, the"
970,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.205882353,"that, the, virus, and, of, identity, to"
971,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.205882353,"that, the, of, genome, a, coronavirus, pan-"
972,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.205882353,"analysis, of, that, sars-cov-2, the, pangolin-cov, and"
973,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.205882353,"the, is, to, one, of, between, and"
974,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.205882353,"a, coronavirus, the, pan-, genome, that, of"
975,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.205882353,"the, and, bats, of, sequence, identity, to"
976,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.205882353,"of, the, analysis, that, is, similar, to"
977,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.205882353,"that, bats, are, the, likely, hosts, for"
978,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.205882353,"the, that, bats, are, likely, hosts, for"
979,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.205128205,"on, genome, bat, origin, of, virus, based, and"
980,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.205128205,"of, the, genome, sequence, and, with, bat, sars-like"
981,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.205128205,"a, that, the, variant, was, to, and, in"
982,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.205128205,"the, of, covid-19, were, market, in, wuhan, city,"
983,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.205128205,"the, ability, of, sars-cov-2, to, be, is, and"
984,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.205128205,"to, available, sars-cov-2, a, that, from, the, as"
985,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.205128205,"the, result, of, natural, spillover, sars-cov-2, to, a"
986,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.205128205,"the, of, evidence, a, natural, spillover, origin, to"
987,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.205128205,"the, and, huanan, market, is, of, a, origin"
988,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.205128205,"the, a, zoonotic, spillover, as, “likely, to, very"
989,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.205128205,"the, genome, sequence, covid-19, and, was, bat, coronavirus"
990,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.205128205,"available, to, the, that, sars-cov-2, as, a, from"
991,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.205128205,"the, coronavirus, from, bat, has, about, identity, with"
992,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.205128205,"the, has, about, identity, with, coronavirus, from, bat"
993,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.205128205,"the, that, virus, to, a, of, and, has"
994,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.205128205,"that, the, started, animals, in, to, humans, and"
995,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.205128205,"with, the, and, sars-like, bat, of, genome, sequence"
996,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.205128205,"the, covid-19, genome, bat, coronavirus, and, sequence, was"
997,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.205128205,"of, that, the, virus, to, bat, and, sars"
998,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.205128205,"the, to, that, started, in, animals, and, humans"
999,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.205128205,"a, of, to, has, that, the, and, virus"
1000,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.205128205,"sars-cov-2, the, in, related, not, that, any, is"
1001,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.205128205,"variant, a, the, to, that, in, and, was"
1002,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.205128205,"sars-cov-2, is, to, be, of, and, the, ability"
1003,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.205128205,"to, the, sars-cov-2, a, result, of, spillover, natural"
1004,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.205128205,"the, banal, related, to, sars-cov-2, measured, by, similarity"
1005,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.205128205,"related, to, measured, by, similarity, banal, sars-cov-2, the"
1006,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.205128205,"of, virus, is, most, to, the, bat, similarity,"
1007,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.205128205,"evidence, to, the, a, of, spillover, natural, origin"
1008,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.205128205,"is, a, and, origin, of, the, huanan, market"
1009,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.205128205,"the, rbd, of, to, that, sars-cov-2, was, humans."
1010,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.205128205,"the, that, is, not, in, any, related, sars-cov-2"
1011,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.205128205,"analysis, of, covid-19, virus, that, to, the, and"
1012,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.205128205,"the, of, most, virus, to, similarity,, is, bat"
1013,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.205128205,"analysis, that, the, covid-19, virus, and, to, of"
1014,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.205128205,"analysis, that, the, evolutionary, of, virus, and, to"
1015,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.205128205,"the, of, were, market, in, wuhan, city,, covid-19"
1016,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.205128205,"and, that, the, virus, to, sars, of, bat"
1017,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.205128205,"based, on, virus, genome, and, bat, of, origin"
1018,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.205128205,"evolutionary, analysis, of, virus, that, to, the, and"
1019,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.205128205,"the, of, rbd, to, that, sars-cov-2, was, humans."
1020,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.204545455,"a, it, was, that, the, sars-cov-2, to, is, sars-cov"
1021,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.204545455,"that, the, sars-cov-2, and, bat, cov, ratg13, share, same"
1022,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.204545455,"the, similarity, and, sequence, virus, is, 96.2%, to, that"
1023,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.204545455,"the, of, evidence, this, sars-cov-2, is, has, been, in"
1024,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.204545455,"the, from, using, that, sars-cov-2, to, a, and, pangolin"
1025,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.204545455,"evolutionary, analysis, of, that, is, to, the, and, was"
1026,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.204545455,"was, that, the, sars-cov-2, is, to, a, it, sars-cov"
1027,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.204545455,"of, is, similar, to, the, bat, sars-like, for, sars-cov-2."
1028,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.204545455,"is, the, to, that, 96.2%, sequence, similarity, virus, and"
1029,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.204545455,"a, of, the, sars-cov-2, genome, with, sars-cov, revealed, and"
1030,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.204545455,"genome, revealed, a, sars-cov-2, and, sars-cov, with, the, of"
1031,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.204545455,"the, analysis, of, and, that, is, was, to, evolutionary"
1032,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.204545455,"the, of, is, similar, to, sars-like, bat, for, sars-cov-2."
1033,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.204545455,"to, sars-cov-2, a, that, from, and, using, the, pangolin"
1034,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.204545455,"that, the, sars-cov-2, bat, cov, ratg13, is, than, same"
1035,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.204545455,"the, bat, cov, ratg13, and, that, sars-cov-2, share, same"
1036,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.204545455,"bat, cov, ratg13, is, the, same, sars-cov-2, that, than"
1037,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.204545455,"the, sars-cov-2, has, been, evidence, in, of, this, is"
1038,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.204081633,"the, sars-cov-2, and, genome, sequence, virus, 96.2%, to, that, bat"
1039,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.204081633,"are, and, the, was, transmitted, from, to, humans,, a, in"
1040,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.204081633,"in, the, a, was, humans,, are, transmitted, from, to, and"
1041,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.204081633,"the, covid-19, virus, originated, in, bats, and, transmitted, to, of"
1042,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.204081633,"that, was, in, patients, were, a, seafood, market, wuhan, china"
1043,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.204081633,"virus, genome, the, to, bat, and, 96.2%, sequence, that, sars-cov-2"
1044,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.204081633,"was, that, patients, wuhan, in, china, seafood, market, were, a"
1045,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.204081633,"the, sars-cov-2, isolated, in, from, of, a, bat, (rhinolophus, yunnan"
1046,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.204081633,"a, sars-cov-2, the, of, isolated, from, bat, (rhinolophus, in, yunnan"
1047,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.204081633,"in, to, of, the, covid-19, virus, originated, bats, and, transmitted"
1048,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.203703704,"to, date, sars-cov-2, a, recombination, of, the, and, has, suggested, that"
1049,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.203703704,"and, also, a, sars-cov-2, receptor, which, is, the, for, to, enzyme"
1050,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.203703704,"a, of, to, date, has, suggested, that, sars-cov-2, the, recombination, and"
1051,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.203703704,"a, the, sars-cov-2, also, enzyme, receptor, and, for, to, which, is"
1052,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.2,"sars-cov-2, and, which, to, a, genetic, in, other, bat, human, coronaviruses"
1053,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.2,"and, other, viruses, closely, related, to, in"
1054,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.2,"a, number, of, unknown, viruses, in"
1055,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.2,"of, globally, distributed, species, reservoir"
1056,"An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.2,"reservoir, of, species, distributed, globally"
1057,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.2,"the, animal, to, be, of, known"
1058,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.2,"bats, are, the, reservoir, of"
1059,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.2,"similar, to, and, sars-cov, in"
1060,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.2,"the, of, in, also, bats"
1061,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.2,"coronavirus, identified, from, been, have"
1062,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.2,"human, and, sars-cov-2, to, bat, coronaviruses, in, a, genetic, which, other"
1063,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.2,"that, the, of, human, coronaviruses, are, bat"
1064,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.2,"a, the, sars-cov, of, bat, is, it, shares, sequence, identity"
1065,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.2,"of, the, sequence, that, sars-cov-2, is, to"
1066,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.2,"a, the, genome, that, was, to, of"
1067,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.2,"are, a, of, viruses, including"
1068,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.2,"compared, the, genome, to, bat, and, sequence"
1069,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.2,"sequence, with, bat, covs, the, of, sars-cov-2, and, mers-cov, sars-cov"
1070,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.2,"of, the, sars-cov-2, genome, with, sars-cov, and"
1071,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.2,"are, most, sars-cov-2, similar, to"
1072,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",hese reservoirs are the bats,0.2,"the, bats, are"
1073,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.2,"bats, as, the, reservoirs, viruses, of, and"
1074,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.2,"virus, that, is, to, a, human"
1075,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.2,"the, is, to, that, origin, in, animal"
1076,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.2,"to, the, a, coronavirus, sars-cov-2, is"
1077,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.2,"the, later, is, to, sars-cov-2"
1078,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.2,"bats, the, natural, of"
1079,"bats are also important reservoir species for a great 

range of coronaviruses","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.2,"bats, are, important, of"
1080,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.2,"for, the, and, civets, intermediate, species, that, virus, into, from, palm, crossed, as, to"
1081,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",Bats are likely reservoir hosts for SARS-CoV-2,0.2,"bats, are, reservoir"
1082,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",Bats are likely reservoir hosts for SARS-CoV-2,0.2,"likely, bats, reservoir, hosts, for"
1083,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.2,"sars-cov-2, is, to, a, coronavirus, the"
1084,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.2,"of, the, analysis, that, sars-cov-2, is"
1085,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.2,"sars-cov-2, that, is, in, bat"
1086,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.2,"in, that, of, sars-cov-2, the, protein"
1087,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.2,"the, genome, of, to, identity, with, that, and, bat"
1088,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.2,"of, that, is, to, the, bat, and"
1089,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.2,"that, bats, are, the, of"
1090,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.2,"that, bats, are, the, for, of"
1091,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","civet cats and raccoon dogs  

are the intermediate hosts",0.2,"the, intermediate, hosts, and"
1092,"Bats are natural hosts of many of the known  

coronaviruses","civet cats and raccoon dogs  

are the intermediate hosts",0.2,"are, hosts, the"
1093,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.2,"to, sars-cov-2, be, bats, and, transmitted, the"
1094,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.2,"bats, the, animal, of, and"
1095,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","with the first case being linked to  

a seafood market",0.2,"the, first, with, seafood, market"
1096,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.2,"scientists, that, the, virus, it, was, not"
1097,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.2,"a, of, available, to, that, sars-cov-2, the"
1098,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.2,"the, a, spillover, from, as, to"
1099,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.2,"the, genome, that, sars-cov-2, through, natural, selection, and"
1100,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.2,"studies, from, wuhan, suggest, the, bat, of, these, and"
1101,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.2,"of, the, hypothesis, that, sars-cov-2"
1102,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.2,"at, zoonotic, jumps, of, sars-cov-2, into, humans, from"
1103,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.2,"of, sars-cov-2, into, humans, zoonotic, jumps, from, at"
1104,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.2,"that, is, sars-cov-2, a, or"
1105,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.2,"the, coronavirus, bat, has, about, with"
1106,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.2,"a, coronavirus, the, with, that, was, to"
1107,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.2,"that, has, the, with, virus, and, similarity, to"
1108,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.2,"compared, the, and, to, bat, genome, sequence"
1109,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.2,"of, known, to, be, the, animal"
1110,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.2,"the, sars-cov-2, bats, and, be, transmitted, to"
1111,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.2,"from, bats, to, is, and, be, the"
1112,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.2,"sars-cov-2, be, a, recombinant, virus, the, and"
1113,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.2,"the, genome, of, identity, with, that, and, to, bat"
1114,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.2,"of, the, genome, covid-19, virus, and, with, bat, coronavirus, identity"
1115,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.2,"that, a, horseshoe, bat, virus, has, genome, of, with"
1116,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.2,"identified, coronavirus, from, have, been"
1117,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.2,"have, been, to, sars-cov-2, the"
1118,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.2,"the, coronavirus, has, about, with, bat"
1119,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.2,"the, sars-cov-2, has, coronavirus, bat"
1120,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.2,"available, to, the, that, sars-cov-2, a, of"
1121,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.2,"a, analysis, of, the, sars-cov-2, that, and"
1122,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.2,"the, and, is, to, bat, of"
1123,"civet cats and raccoon dogs  

are the intermediate hosts","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.2,"and, the, intermediate, hosts"
1124,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.2,"be, the, between, and, of, bat"
1125,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.2,"and, bat, pangolin, to, the, of"
1126,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.2,"the, virus, have, from, in, market, infected, to, and"
1127,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.2,"that, is, part, of, the"
1128,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.2,"in, similar, to, sars-cov, and"
1129,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.2,"the, that, to, animal, in, is, origin"
1130,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.2,"the, that, is, in, to"
1131,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.2,"the, and, of, sequence, virus, is, to, that"
1132,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.2,"that, the, virus, of, and, to"
1133,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.2,"bats, to, be, the, of, virus"
1134,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.2,"the, sequence, of, is, a, bat, it, shares, identity, sars-cov"
1135,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.2,"bats, of, are, the, reservoir"
1136,Wet Market animals maintained in poor conditions,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.2,"wet, market, animals, in"
1137,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.2,"not, that, the, virus, was, it, scientists"
1138,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.2,"the, coronavirus, bat, has, sars-cov-2"
1139,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.2,"of, the, coronavirus, has, bat, human"
1140,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.2,"with, the, sars-cov, and, mers-cov, sars-cov-2, bat, covs, of, sequence"
1141,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.2,"the, are, of, bat, coronaviruses, that, human"
1142,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.2,"reservoir, of, has, been, that, the"
1143,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.2,"it, that, are, the, reservoir, bat"
1144,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.2,"is, that, the, virus, and, of, sequence, to"
1145,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.2,"the, sars-cov-2, genome, to, 96.2%, identical, bat"
1146,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.2,"the, most, virus, in, covid-19"
1147,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.2,"a, is, to, that, human, virus"
1148,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.2,"virus, human, from, an, animal, to"
1149,"zoonotic corona- 

viruses have become an increasing threat to human health,","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.2,"zoonotic, an, to, human"
1150,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.2,"the, bats, also, in, of"
1151,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.2,"have, the, virus, in, and, to, from, infected, market"
1152,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.2,"virus, from, an, animal, to, human"
1153,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.2,"is, humans, and, that, sars-cov-2, another, animal, species"
1154,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.2,"the, sars-cov-2, animal, and, humans"
1155,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.2,"is, that, sars-cov-2, species, and, humans, another, animal"
1156,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.2,"that, the, virus, and, of, to"
1157,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.2,"the, virus, covid-19, genome, of, identity, with, coronavirus, and, bat"
1158,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.2,"of, covid-19, virus, the, bat, sars-like, and, was"
1159,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.2,"ratg13,, was, the, closest, relationship, with, identity, genome"
1160,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",COVID-19 is a zoonotic virus,0.2,"a, virus, is"
1161,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.2,"the, virus, bats, be, of, to"
1162,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.2,"that, the, sequence, of, sars-cov-2, is, to"
1163,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.2,"the, of, has, human, coronavirus, bat"
1164,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.2,"that, sars-cov-2, through, natural, selection, and, the, genome"
1165,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.2,"genome, from, in, china, the, bat, of, virus, between, and"
1166,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.2,"that, sars-cov-2, is, in, bat"
1167,COVID-19 is a zoonotic virus,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.2,"is, a, virus"
1168,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.2,"sars-cov-2, is, a, from, bat, that, may, endemic, in"
1169,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.2,"a, virus, that, sars-cov-2, in, bat"
1170,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.2,"that, sars-cov-2, is, a, virus"
1171,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.2,"that, sars-cov-2, from, a, bat, in"
1172,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.2,"with, the, sars-cov, and, sars-cov-2, of, genome"
1173,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.2,"a, analysis, of, that, sars-cov-2, the, and"
1174,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.2,"sars-cov-2, the, and, humans, animal"
1175,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.2,"the, of, sars-, to, likely, bats, hosts"
1176,"civet cats and raccoon dogs  

are the intermediate hosts","Bats are natural hosts of many of the known  

coronaviruses",0.2,"are, the, hosts"
1177,Coronaviruses account for over 30% of the world’s viruses.,"Bats are natural hosts of many of the known  

coronaviruses",0.2,"coronaviruses, of, the"
1178,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.2,"sars-cov-2, may, from, a, that, is, endemic, in, bat"
1179,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.2,"is, the, most, to, be"
1180,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.2,"research, a, strain, has, similarity, with, sars-cov-2"
1181,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.2,"of, virus, that, it, is, to, the, and"
1182,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.2,"was, that, the, genome, of, to, a"
1183,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.2,"the, was, a, coronavirus, that, with, to"
1184,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.2,"hypothesis, that, sars-cov-2, the, of"
1185,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.2,"of, to, a, ratg13,, was, from, bat, in, yunnan"
1186,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.2,"found, that, sars-cov-2, similar, to, pangolin, hypothesis, the, of"
1187,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.2,"bat, and, variety, in, the, of"
1188,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.2,"of, viruses, in, reservoirs, and, to, the"
1189,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.2,"the, is, to, that, in"
1190,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.2,"virus, has, a, genome, of, with, that, horseshoe, bat"
1191,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.2,"a, research, has, strain, similarity, with, sars-cov-2"
1192,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.2,"found, in, yunnan, has, with, 96.2%, genome"
1193,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.2,"sars-cov-2, is, to, later, the"
1194,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.2,"that, sars-cov-2, is, the"
1195,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.2,"that, is, the, sars-cov-2"
1196,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.2,"the, of, that, is, a, has, been, animal"
1197,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.2,"ratg13, the, amino, acid, sequence, rbd, of, s"
1198,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.2,"suggest, that, pangolins, be, the, hosts, for, sars-cov-2, based, on"
1199,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.2,"suggest, that, may, with, to, and, pangolins, the, intermediate, hosts, for, sars-cov-2"
1200,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.2,"to, the, as, a, spillover, from"
1201,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.2,"the, to, in, sars-cov-2, and"
1202,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",Wet Market animals maintained in poor conditions,0.2,"animals, in, wet, market"
1203,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.2,"the, progenitor, virus, closely, related, to, in"
1204,"Bats are natural hosts of many of the known  

coronaviruses",Coronaviruses account for over 30% of the world’s viruses.,0.2,"of, the, coronaviruses"
1205,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.2,"bats, the, as, reservoirs, of, and, viruses"
1206,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.2,"the, animal, of, bats, and"
1207,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.2,"the, to, are, in, sars-cov-2, and"
1208,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.2,"and, closely, related, to, in, other, viruses"
1209,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.2,"the, to, closely, related, progenitor, virus, in"
1210,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.2,"the, of, variety, and, in, bat"
1211,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.2,"of, at, the, s1/s2, cleavage, site, spike, a, furin"
1212,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.2,"is, the, most, closely, related, virus, to"
1213,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.2,"the, virus, covid-19, most, in"
1214,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.2,"the, is, to, be, most"
1215,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.2,"the, most, closely, related, virus, to, is"
1216,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.2,"from, as, intermediate, that, virus, to, for, and, crossed, the, species, into, palm, civets"
1217,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.2,"is, that, the, most, for, sars-cov-2, to, a"
1218,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.2,"viruses, in, a, unknown, number, of"
1219,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.2,"to, the, viruses, in, reservoirs, and, of"
1220,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.2,"shows, that, sars-cov-2, the, with, (ratg13), virus, genome,"
1221,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.2,"that, is, sars-cov-2, a, laboratory"
1222,Bats are likely reservoir hosts for SARS-CoV-2,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.2,"bats, likely, reservoir, hosts, for"
1223,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.2,"bats, to, the, likely, hosts, of, sars-"
1224,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.2,"to, that, sars-, cov-2, the, of, bats, as, hosts, for"
1225,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.2,"natural, insertions, of, the, cleavage, site, a, that, can, occur"
1226,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.2,"are, of, a, including, viruses"
1227,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.2,"covs, are, to, be, in"
1228,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.2,"covs, are, in, be, to"
1229,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.2,"the, of, that, and, is, to, bat"
1230,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.2,"of, the, covid-19, virus, and, was, bat, sars-like"
1231,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.2,"the, is, that, virus, to, of, and, it"
1232,"with the first case being linked to  

a seafood market","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.2,"with, the, first, seafood, market"
1233,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.2,"in, the, of, first, patients, market"
1234,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.2,"to, is, be, from, bats, and, the"
1235,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.2,"is, to, the, from, between, and, scenario, be"
1236,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.2,"the, of, first, patients, market, in"
1237,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","t some virus detected in pangolins 

were capable of infecting humans.",0.2,"in, pangolins, were, of"
1238,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.2,"sars-cov-2, a, virus, that, is"
1239,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","zoonotic corona- 

viruses have become an increasing threat to human health,",0.2,"an, to, human, zoonotic"
1240,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.2,"sars-cov-2, from, a, that, in, bat"
1241,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.2,"has, been, that, the, of, reservoir"
1242,SARS-CoV-2 was created from SARS-CoV-2,The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.2,"sars-cov-2, was"
1243,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.2,"the, sars-cov-2, genome, 96.2%, identical, to, bat"
1244,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.2,"found, sars-cov-2, genome, to, cov, the"
1245,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.2,"from, to, is, between, and, be, the, scenario"
1246,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.2,"suggest, that, be, hosts, for, sars-cov-2, pangolins, based, on, the"
1247,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.2,"are, and, evidence, that, bats, pangolins, hosts, for"
1248,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.2,"that, bats, are, hosts, for, and"
1249,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.2,"most, sars-cov-2, are, similar, to"
1250,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.2,"it, that, the, are, bat, reservoir"
1251,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.2,"sars-cov-2, is, a, that, to, the, most, for"
1252,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.2,"that, a, similar, to, are, the, hosts, for, sars-cov-2"
1253,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.2,"ratg13,, to, was, in, from, of, a, bat, yunnan"
1254,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.2,"found, genome, sequences, similar, to, pangolin, and, of, sars-cov-2."
1255,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.2,"suggest, that, and, may, intermediate, hosts, for, sars-cov-2, to, pangolins, the, with"
1256,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.2,"that, are, the, hosts, for, sars-cov-2, similar, to, a"
1257,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.2,"the, been, to, have, sars-cov-2"
1258,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.2,"is, that, the, part, of"
1259,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.2,"the, that, is, sars-cov-2"
1260,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.2,"evidence, that, bats, and, pangolins, are, hosts, for"
1261,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.2,"of, the, that, bats, are"
1262,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.2,"the, of, sars-, cov-2, to, that, bats, as, hosts, for"
1263,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.2,"studies, these, and, suggest, from, the, bat, wuhan, of"
1264,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.2,"genome, between, and, the, of, virus, from, bat, in, china"
1265,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.2,"hypothesis, found, the, of, that, sars-cov-2, to, similar, pangolin"
1266,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.2,"the, sars-cov-2, genome, found, to, cov"
1267,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.2,"found, of, pangolin, genome, sequences, and, similar, to, sars-cov-2."
1268,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.2,"virus, (ratg13), that, shows, with, the, sars-cov-2, genome,"
1269,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.2,"for, recombination, bat-sl-cov-2, and, the"
1270,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.2,"that, sars-cov-2, the, bat-sl-cov-2, of, and, pangolin-cov"
1271,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.2,"recombination, the, for, bat-sl-cov-2, and"
1272,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.2,"the, in, sars-cov-2, and, pangolin-cov"
1273,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.2,"of, the, that, bats, are, for"
1274,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.2,"that, bats, and, are, hosts, for"
1275,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.2,"sars-cov-2, the, with, bat-sl-cov-2, and, similarity, pangolin-cov"
1276,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.2,"to, sars-cov-2, and, in, the"
1277,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.2,"the, to, are, sars-cov-2, in, and"
1278,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.2,"and, pangolin-cov, in, the, sars-cov-2"
1279,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.2,"the, be, of, between, bat, and"
1280,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.2,"sars-cov-2, be, a, recombinant, virus, and, the"
1281,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.2,"the, that, animal, of, has, been, is, a"
1282,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.2,"the, genome, closest, relationship, was, with, ratg13,, identity"
1283,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.2,"found, in, yunnan, has, genome, 96.2%, with"
1284,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.2,"the, that, sars-cov-2, protein, in, of"
1285,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.2,"of, the, a, furin, cleavage, site, at, s1/s2, spike"
1286,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.2,"insertions, can, occur, the, of, that, cleavage, site, a, natural"
1287,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.2,"ratg13, s, the, sequence, of, rbd, amino, acid"
1288,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.2,"the, pangolin, to, of, bat, and"
1289,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.198412698,"the, live, to, in, wet, markets, a, for, of, as, one, horseshoe, bats,, southern, sars, multiple, infected, virus, were, by, animal, and, palm, other, mammals,"
1290,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.198412698,"infected, to, a, palm, as, animal, in, multiple, for, the, virus, by, wet, markets, southern, sars, live, were, one, of, and, other, mammals,, bats,, horseshoe"
1291,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.196721311,"a, from, who, at, market, in, china, that, the, virus, to, bats"
1292,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.196721311,"sars-cov, and, mers-cov,, sars-, to, the, be, natural, palm, dromedary, or, intermediate"
1293,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.196721311,"to, the, sars-, and, mers-cov,, natural, palm, or, be, intermediate, sars-cov, dromedary"
1294,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.196721311,"a, by, from, who, was, at, seafood, market, wuhan, the, to, of"
1295,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.196721311,"that, the, virus, in, bats, to, from, who, at, a, market, china"
1296,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.196721311,"the, by, was, from, a, who, at, seafood, market, to, of, wuhan"
1297,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.196078431,"in, a, other, closely, related, and, which, are, to, sars-cov-2"
1298,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.196078431,"that, of, sars-, cov-2, to, a, coronavirus, in, with, the"
1299,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.196078431,"a, coronavirus, in, the, with, that, to, of, sars-, cov-2"
1300,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.196078431,"and, sars-cov-2, are, closely, related, to, in, a, which, other"
1301,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.196078431,"have, been, and, in, their, the, of, sars-cov-2, origin, is"
1302,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.196078431,"of, the, sars-cov-2, have, been, in, their, origin, is, and"
1303,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.195652174,"the, is, to, be, of, between, bat, and, human"
1304,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.195652174,"the, of, sars-cov-2, to, result, natural, a, that, evidence"
1305,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.195652174,"the, covid-19, a, genome, to, that, coronavirus, and, bat"
1306,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.195652174,"of, the, cases, in, to, were, with, huanan, market"
1307,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.195652174,"the, covid-19, genome, to, bat, coronavirus, and, that, a"
1308,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.195652174,"the, between, and, to, be, of, is, bat, human"
1309,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.195652174,"studies, that, sars-cov-2, sequences, to, and, on, the, of"
1310,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.195652174,"it, was, that, the, wuhan, in, seafood, market, where"
1311,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.195652174,"that, seafood, market, in, wuhan, the, it, was, where"
1312,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.195652174,"is, the, bat, coronavirus, to, be, of, s, than"
1313,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.195652174,"a, virus, sequence, identity, with, the, sars-cov-2, in, bat"
1314,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.195652174,"the, of, cases, were, in, to, with, huanan, market"
1315,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.195652174,"all, sars-cov-2, including, the, and, in, related, coronaviruses, that"
1316,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.195652174,"of, three, amino, acids, the, cleavage, site, furin, insertion"
1317,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.195652174,"a, sequence, identity, sars-cov-2, with, the, virus, bat, in"
1318,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.195652174,"evidence, to, the, that, sars-cov-2, a, result, of, natural"
1319,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.195652174,"the, coronaviruses, that, related, sars-cov-2, all, in, and, including"
1320,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.195652174,"genome, sequences, obtained, from, in, bat, of, these, previously"
1321,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.195652174,"have, that, are, the, hosts, for, a, of, and"
1322,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.195652174,"of, these, sequences, genome, previously, obtained, from, bat, in"
1323,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.195652174,"studies, on, the, of, and, sequences, that, sars-cov-2, to"
1324,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.195652174,"that, have, a, of, and, are, the, hosts, for"
1325,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.195652174,"the, furin, cleavage, site, of, three, amino, acids, insertion"
1326,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.195652174,"s, the, of, coronavirus, is, than, to, bat, be"
1327,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.195121951,"the, coronaviruses, to, that, are, all, bat, and"
1328,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.195121951,"of, the, genome, sequence, was, bat, ratg13,, identity"
1329,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.195121951,"the, genome, sars-cov-2, identity, that, and, to, bat"
1330,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.195121951,"is, sars-cov-2, and, bat, compared, to, the, in"
1331,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.195121951,"to, is, a, virus, that, and, was, the"
1332,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.195121951,"the, of, and, sars-cov-2, is, an, animal, to"
1333,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.195121951,"genome, the, to, bat, and, identity, that, sars-cov-2"
1334,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.195121951,"sars-cov-2, a, natural, that, into, humans, to, the"
1335,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.195121951,"that, the, cases, in, to, a, huanan, market"
1336,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.195121951,"the, of, in, with, a, and, huanan, market"
1337,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.195121951,"to, a, virus, that, and, was, the, as"
1338,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.195121951,"in, a, that, the, cases, to, huanan, market"
1339,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.195121951,"with, a, and, of, the, huanan, market, in"
1340,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.195121951,"the, that, has, of, virus, genome,, and, to"
1341,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.195121951,"a, is, the, to, that, virus, and, was"
1342,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.195121951,"the, virus, was, as, a, that, and, to"
1343,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.195121951,"of, pangolin, one, to, and, the, intermediate, hosts"
1344,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.195121951,"sars-cov-2, is, to, of, an, animal, and, the"
1345,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.195121951,"the, in, and, seafood, market,, december, of, 2019"
1346,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.195121951,"of, the, sequence, that, sars-cov-2, is, to, beta"
1347,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.195121951,"sars-cov-2, et, al.,, and, to, the, of, betacoronavirus"
1348,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.195121951,"another, be, of, sars-cov-2, and, an, animal, intermediate"
1349,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.195121951,"was, the, genome, sequence, of, bat, ratg13,, identity"
1350,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.195121951,"the, sars-cov-2, beta, of, sequence, is, to, that"
1351,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.195121951,"other, that, sars-cov-2, genome, and, a, on, the"
1352,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.195121951,"the, sars-cov-2, and, betacoronavirus, of, et, al.,, to"
1353,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.195121951,"that, pangolin, and, a, hypothesis, on, the, of"
1354,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.195121951,"the, covid-19, pandemic, is, of, sars-cov-2, or, to"
1355,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.195121951,"et, al., (2020), in, to, the, sars-cov-2, has"
1356,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.195121951,"et, al., (2020), has, the, to, sars-cov-2, in"
1357,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.195121951,"is, the, of, to, sars-cov-2, or, covid-19, pandemic"
1358,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.195121951,"the, and, are, all, bat, coronaviruses, that, to"
1359,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.195121951,"to, the, that, sars-cov-2, a, into, humans, natural"
1360,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.195121951,"96.2%, sequence, identity, with, bat, that, sars-cov-2, a"
1361,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.195121951,"seafood, market,, in, the, december, 2019, and, of"
1362,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.195121951,"a, sequence, that, 96.2%, identity, with, sars-cov-2, bat"
1363,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.195121951,"in, the, rbd, of, to, sars-cov-2, which, bind"
1364,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.195121951,"phylogenetic, analysis, that, the, of, virus, and, to"
1365,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.195121951,"the, pangolin, to, one, of, intermediate, hosts, and"
1366,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.195121951,"compared, the, and, sars-cov-2, is, to, bat, in"
1367,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.195121951,"on, the, other, genome, that, sars-cov-2, and, a"
1368,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.195121951,"the, pangolin, hypothesis, and, on, that, a, of"
1369,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.195121951,"of, phylogenetic, analysis, that, the, virus, to, and"
1370,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.195121951,"the, virus, has, genome,, to, that, of, and"
1371,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.195121951,"and, of, phylogenetic, tree, bat-sl-cov-2, pangolin-cov, with, at"
1372,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.195121951,"rbd, of, sars-cov-2, to, bind, which, the, in"
1373,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.195121951,"phylogenetic, tree, with, bat-sl-cov-2, at, of, and, pangolin-cov"
1374,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.195121951,"and, of, sars-cov-2, an, intermediate, another, animal, be"
1375,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.195121951,"in, the, of, that, sars-cov-2, was, to, similar"
1376,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.194444444,"sars-cov-2, the, of, shares, sequence, identity, sars-cov"
1377,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.194444444,"of, the, sequence, that, ratg13,, sars-cov-2, is"
1378,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.194444444,"of, is, to, the, bat, sars-like, and"
1379,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.194444444,"the, sequence, of, sars-cov-2, shares, identity, sars-cov"
1380,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.194444444,"due, to, the, from, zoonotic, a, with"
1381,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.194444444,"the, of, 80%, identity, to, sars-cov, and"
1382,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.194444444,"the, that, sars-cov-2, with, of, and, to"
1383,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.194444444,"identified, from, the, has, been, to, sars-cov-2"
1384,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.194444444,"from, bats, to, humans, is, be, the"
1385,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.194444444,"the, hypothesis, of, natural, origin, a, as"
1386,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.194444444,"of, lineage, a, at, the, huanan, market"
1387,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.194444444,"a, of, lineage, at, the, huanan, market"
1388,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.194444444,"that, a, bat, virus, has, similarity, with"
1389,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.194444444,"that, the, genome, a, bat, coronavirus, covid-19"
1390,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.194444444,"covid-19, that, to, the, bat, and, was"
1391,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.194444444,"covid-19, the, huanan, market, in, wuhan, december"
1392,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.194444444,"is, that, sars-cov-2, the, and, from, host."
1393,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.194444444,"the, sars-cov-2, as, a, recombinant, from, and"
1394,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.194444444,"the, identified, sars-cov-2, has, been, to, from"
1395,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.194444444,"the, from, sars-cov-2, to, a, pangolin, coronavirus"
1396,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.194444444,"analysis, of, virus, that, to, the, and"
1397,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.194444444,"is, and, bat, pangolin, to, the, between"
1398,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.194444444,"the, huanan, seafood, wholesale, in, december, 2019"
1399,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.194444444,"that, the, virus, bats, and, to, of"
1400,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.194444444,"the, is, of, to, closely, related, in"
1401,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.194444444,"sars-cov-2, is, that, from, and, the, host."
1402,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.194444444,"of, the, hypothesis, that, is, a, virus"
1403,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.194444444,"the, in, of, similar, to, that, was"
1404,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.194444444,"that, genome, similar, to, a, the, of"
1405,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.194444444,"the, of, scientific, that, sars-cov-2, is, a"
1406,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.194444444,"covid-19, in, december, the, huanan, market, wuhan"
1407,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.194444444,"huanan, seafood, wholesale, in, the, december, 2019"
1408,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.194444444,"sars-cov-2, a, recombinant, from, and, the, as"
1409,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.194444444,"the, between, and, of, a, natural, origin"
1410,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.194444444,"the, of, a, has, been, in, populations"
1411,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.194444444,"virus, a, that, has, with, bat, similarity"
1412,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.194444444,"that, sars-cov-2, has, with, of, virus, similarity"
1413,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.194444444,"that, the, sequence, of, sars-cov-2, is, ratg13,"
1414,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.194444444,"and, species, to, an, in, the, of"
1415,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.194444444,"live, animal, at, and, in, the, to"
1416,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.194444444,"bats, are, the, reservoir, for, of, including"
1417,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.194444444,"the, of, in, is, closely, related, to"
1418,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.194444444,"that, are, the, most, sars-cov-2, to, bat"
1419,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.194444444,"in, an, species, of, to, and, the"
1420,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.194444444,"the, of, sars-, cov-2, to, is, that"
1421,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.194444444,"the, natural, origin, of, a, between, and"
1422,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.194444444,"animal, to, live, and, in, at, the"
1423,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.194444444,"the, of, to, is, that, sars-, cov-2"
1424,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.194444444,"the, covid-19, genome, bat, coronavirus, that, a"
1425,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.194444444,"the, of, 80%, identity, sars-cov, and, to"
1426,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.194444444,"that, the, virus, and, bats, of, to"
1427,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.194444444,"the, and, is, to, sars-like, bat, of"
1428,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.194444444,"the, covid-19, to, bat, and, that, was"
1429,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.194444444,"analysis, of, to, that, the, and, virus"
1430,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.194444444,"the, to, humans, from, bats, is, be"
1431,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.194444444,"is, the, most, likely, for, to, a"
1432,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.194444444,"the, hypothesis, is, that, virus, a, of"
1433,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.194444444,"that, a, wildlife, host, sars-cov-2, to, directly"
1434,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.194444444,"that, sars-cov-2, directly, a, to, wildlife, host"
1435,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.194444444,"the, hypothesis, as, a, of, natural, origin"
1436,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.194444444,"a, coronavirus, from, the, pangolin, to, sars-cov-2"
1437,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.194444444,"the, to, that, are, most, sars-cov-2, bat"
1438,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.194444444,"the, to, for, a, is, most, likely"
1439,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.194444444,"the, pangolin, is, to, between, bat, and"
1440,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.194444444,"a, the, genome, that, similar, to, of"
1441,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.194444444,"the, of, evidence, that, sars-cov-2, in, for"
1442,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.194444444,"the, of, sars-cov-2, with, that, and, to"
1443,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.194444444,"that, virus, has, similarity, of, with, sars-cov-2"
1444,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.194444444,"due, to, the, with, a, from, zoonotic"
1445,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.194444444,"of, scientific, the, that, sars-cov-2, is, a"
1446,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.194444444,"evidence, for, that, in, the, of, sars-cov-2"
1447,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.193548387,"to, be, of, animal, and, the"
1448,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.193548387,"bats, to, be, the, reservoir, of"
1449,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.193548387,"it, is, that, sars-cov-2, of, a"
1450,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.193548387,"a, of, viruses, natural, and, the"
1451,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.193548387,"the, of, sars-cov-2, is, with, and"
1452,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.193548387,"of, and, to, be, the, animal"
1453,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.193548387,"of, the, sars-cov-2, coronavirus, is, to"
1454,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.193548387,"the, sequence, sars-cov-2, coronavirus, is, to"
1455,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.193548387,"was, to, bats,, the, in, animals"
1456,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.193548387,"the, of, sars-cov-2, that, is, bat"
1457,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.193548387,"the, that, sars-cov-2, is, of, bat"
1458,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.193548387,"bats, are, the, natural, for, of"
1459,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.193548387,"a, that, originated, by, the, and"
1460,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.193548387,"sars-cov-2, from, a, that, this, bat"
1461,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.193548387,"sars-cov-2, from, viruses, that, are, to"
1462,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.193548387,"are, animals, and, be, to, through"
1463,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.193548387,"in, the, of, a, and, market"
1464,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.193548387,"in, these, viruses, were, to, animal"
1465,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.193548387,"there, is, that, had, sars-cov-2, or"
1466,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.193548387,"this, that, the, is, and, animals"
1467,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.193548387,"the, and, by, a, that, originated"
1468,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.193548387,"of, is, to, the, bat, and"
1469,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.193548387,"the, virus, to, and, its, in"
1470,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.193548387,"a, the, that, was, of, at"
1471,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.193548387,"its, and, the, virus, to, in"
1472,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.193548387,"bats, of, and, to, be, the"
1473,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.193548387,"of, the, sequence, that, is, to"
1474,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.193548387,"bats, to, be, the, of, may"
1475,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.193548387,"it, is, the, for, to, a"
1476,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.193548387,"the, also, closely, related, to, of"
1477,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.193548387,"of, the, indicated, that, coronavirus, to"
1478,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.193548387,"and, to, the, lineage, of, betacoronavirus"
1479,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.193548387,"bats, of, to, be, the, reservoir"
1480,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.193548387,"sars-cov-2, is, to, of, coronavirus, the"
1481,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.193548387,"to, the, sequence, coronavirus, sars-cov-2, is"
1482,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.193548387,"is, that, the, of, sequence, to"
1483,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.193548387,"indicated, that, the, of, coronavirus, to"
1484,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.193548387,"the, to, in, seafood, market, wuhan,"
1485,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.193548387,"a, bat, that, sars-cov-2, from, this"
1486,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.193548387,"other, sars-cov-2, are, and, the, of"
1487,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.193548387,"the, bats, may, be, of, to"
1488,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.193548387,"at, that, the, was, of, a"
1489,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.193548387,"the, of, and, to, betacoronavirus, lineage"
1490,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.193548387,"the, for, and, viruses, to, in"
1491,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.193548387,"and, pangolin-cov, that, the, of, sars-cov-2"
1492,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.193548387,"of, the, covid-19, cases, were, approximately, associated, with, huanan, seafood, earliest, known"
1493,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.193548387,"in, the, of, intermediate, host, was, outbreak, at, that, samples, taken, from"
1494,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.193548387,"of, the, bats, are, natural, for"
1495,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.193548387,"the, of, bats, serve, as, for"
1496,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.193548387,"to, the, for, viruses, in, and"
1497,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.193548387,"the, of, also, closely, related, to"
1498,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.193548387,"banal, series, also, the, of, spike"
1499,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.193548387,"the, banal, series, also, of, spike"
1500,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.193548387,"approximately, of, the, earliest, known, covid-19, cases, were, associated, with, huanan, seafood"
1501,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.193548387,"the, of, in, samples, taken, from, that, intermediate, host, was, at, outbreak"
1502,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.193548387,"the, natural, of, a, and, viruses"
1503,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.193548387,"that, of, sars-cov-2, is, a, it"
1504,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.193548387,"bats, serve, as, the, for, of"
1505,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.193548387,"through, animals, are, to, be, and"
1506,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.193548387,"these, were, viruses, in, to, animal"
1507,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.193548387,"the, seafood, market, in, wuhan,, to"
1508,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.193548387,"a, and, of, the, market, in"
1509,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.193548387,"that, the, and, animals, this, is"
1510,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.193548387,"viruses, are, to, that, sars-cov-2, from"
1511,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.193548387,"the, was, in, bats,, to, animals"
1512,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.193548387,"that, bats, pangolins, hosts, for, sars-cov-2"
1513,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.193548387,"a, to, for, the, it, is"
1514,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.193548387,"the, of, sars-cov-2, are, and, other"
1515,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.193548387,"with, the, and, sars-cov-2, is, of"
1516,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.193548387,"of, the, that, pangolin-cov, and, sars-cov-2"
1517,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.193548387,"that, in, and, the, for, of"
1518,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.193548387,"for, and, that, in, the, of"
1519,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.192307692,"coronaviruses, a, large, of, viruses"
1520,"bats are also important reservoir species for a great 

range of coronaviruses","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.192307692,"bats, are, reservoir, species, of"
1521,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.192307692,"is, virus, to, sars-cov-2, in"
1522,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.192307692,"it, suggested, that, the, infected, wuhan, in, market, were, of"
1523,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.192307692,"is, an, animal, to, a"
1524,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.192307692,"the, of, sars-cov-2, animal, and"
1525,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.192307692,"is, from, to, a, zoonotic"
1526,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.192307692,"the, to, and, sars-cov, in"
1527,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.192307692,"that, the, from, a, animals, in, transmitted, to, humans, and"
1528,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.192307692,"the, to, be, of, and"
1529,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.192307692,"bats, are, the, of, sars-cov-2"
1530,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.192307692,"the, and, that, origin, in"
1531,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.192307692,"that, the, of, cases, in, with, and, around, huanan, market"
1532,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.192307692,"the, of, with, and, cases, around, huanan, market, that, in"
1533,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.192307692,"coronavirus, with, similarity, to, sars-cov-2"
1534,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.192307692,"the, of, and, be, to"
1535,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.192307692,"is, humans, and, that, of, sars-cov-2, to, an, animal, by"
1536,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.192307692,"the, sars-cov, in, and, to"
1537,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.192307692,"the, origin, and, that, in"
1538,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.192307692,"the, virus, and, to, in"
1539,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.192307692,"the, in, that, animal, origin"
1540,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.192307692,"virus, that, is, to, zoonotic"
1541,"This suggests that the BANAL series may be able to directly infect  

humans.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.192307692,"that, the, may, be, to"
1542,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.192307692,"the, of, infected, that, were, market, in, wuhan, it, suggested"
1543,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.192307692,"the, genetic, sequence, of, 80%, sars-cov, and, 50%, cov, mers-cov"
1544,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.192307692,"bats, the, reservoir, covid-19, virus"
1545,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.192307692,"is, to, a, an, animal"
1546,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.192307692,"to, a, from, is, zoonotic"
1547,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.192307692,"is, that, virus, zoonotic, to"
1548,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.192307692,"coronaviruses, are, closely, related, to"
1549,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.192307692,"of, and, that, sars-cov-2, is, an, animal, to, humans, by"
1550,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",COVID-19 is a zoonotic virus,0.192307692,"covid-19, is, zoonotic, a, virus"
1551,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.192307692,"the, virus, covid-19, reservoir, bats"
1552,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.192307692,"in, the, a, that, transmitted, from, animals, to, humans, and"
1553,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.192307692,"sars-cov-2, of, animal, and, the"
1554,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.192307692,"the, of, sars-cov-2, and, animal"
1555,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.192307692,"study, evidence, that, the, of, may, potential, to, as, intermediate"
1556,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.192307692,"the, that, strain, similar, to"
1557,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.192307692,"to, are, closely, related, coronaviruses"
1558,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.192307692,"is, that, sars-cov-2, of, a"
1559,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.192307692,"the, sars-cov-2, was, to, cov"
1560,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.192307692,"the, of, has, been, in"
1561,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.192307692,"the, of, in, has, been"
1562,"a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.192307692,"a, shared, similarity, with, sars-cov-2"
1563,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.192307692,"a, sars-cov-2, shared, similarity, with"
1564,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.192307692,"strain, the, that, similar, to"
1565,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.192307692,"similar, to, that, sars-cov-2, the"
1566,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","bats are also important reservoir species for a great 

range of coronaviruses",0.192307692,"bats, of, species, are, reservoir"
1567,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.192307692,"sars-cov-2, in, several, animal, species"
1568,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.192307692,"coronavirus, to, similarity, with, sars-cov-2"
1569,COVID-19 is a zoonotic virus,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.192307692,"covid-19, is, a, zoonotic, virus"
1570,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.192307692,"the, virus, to, and, in"
1571,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.192307692,"virus, is, to, sars-cov-2, in"
1572,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.192307692,"of, that, sars-cov-2, is, a"
1573,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.192307692,"cov, sequence, the, of, and, genetic, 50%, mers-cov, 80%, sars-cov"
1574,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.192307692,"coronaviruses, of, a, large, viruses"
1575,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.192307692,"in, transmitted, to, humans, through"
1576,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.192307692,"the, of, sars-cov-2, was, not"
1577,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.192307692,"several, animal, species, sars-cov-2, in"
1578,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.192307692,"sars-cov-2, was, to, cov, the"
1579,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.192307692,"the, origin, bat, cov, or"
1580,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.192307692,"the, bat, or, origin, cov"
1581,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.192307692,"the, of, sars-cov-2, are, bats"
1582,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.192307692,"the, that, origin, in, animal"
1583,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.192307692,"the, that, similar, to, sars-cov-2"
1584,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.192307692,"the, study, of, that, may, as, potential, intermediate, evidence, to"
1585,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.191489362,"a, coronavirus, in, the, with, that, was, to, at"
1586,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.191489362,"even, though, the, to, this, has, been, in, of"
1587,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.191489362,"the, sars-cov-2, animal, at, huanan, market, that, in, and"
1588,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.191489362,"the, animal, and, huanan, market, that, sars-cov-2, at, in"
1589,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.191489362,"of, covid-19, virus, that, to, the, bat, and, for"
1590,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.191489362,"he, from, pangolins, similar, with, sars-cov-2, the, of, protein"
1591,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.191489362,"the, of, virus, to, that, sars-cov-2, has, and, a"
1592,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.191489362,"are, in, to, the, virus, bats, and, was, transmitted"
1593,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.191489362,"that, the, virus, in, bats, and, to, humans, through"
1594,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.191489362,"are, and, the, virus, was, transmitted, bats, to, in"
1595,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.191489362,"in, the, a, coronavirus, was, that, to, at, with"
1596,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.191489362,"a, of, to, has, that, sars-cov-2, the, and, virus"
1597,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.191489362,"and, a, of, in, their, which, the, viruses, to"
1598,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.191489362,"through, that, the, virus, in, bats, and, to, humans"
1599,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.191489362,"the, virus, for, covid-19, of, to, that, and, bat"
1600,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.191489362,"the, has, been, to, even, though, in, of, this"
1601,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.191489362,"he, pangolins, similar, from, with, the, protein, of, sars-cov-2"
1602,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.191489362,"a, of, viruses, in, their, and, to, which, the"
1603,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.191489362,"bat, sars, cov, and, the, same, sars-cov-2, ratg13, guangdong"
1604,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.191489362,"the, sars-cov-2, and, bat, cov, ratg13, guangdong, sars, same"
1605,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.191176471,"bat, cov, and, the, they, are, 16, sars-cov-2, representatives, cluster, with, ratg13, guangdong"
1606,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.191176471,"with, the, and, sars-cov-2, bat, cov, ratg13, guangdong, are, they, 16, representatives, cluster"
1607,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.19047619,"is, to, sars-cov-2, than"
1608,"bats are also important reservoir species for a great 

range of coronaviruses","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.19047619,"bats, are, also, of"
1609,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.19047619,"ratg13,, the, to, sars-cov-2, was, of, a, bat"
1610,"Bats are natural hosts of many of the known  

coronaviruses","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.19047619,"are, natural, of, the"
1611,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.19047619,"to, sars-cov-2, from, bats, humans,, the, as, intermediate"
1612,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.19047619,"the, of, are, and"
1613,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","civet cats and raccoon dogs  

are the intermediate hosts",0.19047619,"the, are, and, dogs"
1614,"civet cats and raccoon dogs  

are the intermediate hosts","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.19047619,"and, dogs, are, the"
1615,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","with the first case being linked to  

a seafood market",0.19047619,"the, market, to, with"
1616,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.19047619,"that, sars-cov-2, of, the"
1617,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.19047619,"that, the, of, sars-cov-2"
1618,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.19047619,"the, of, that, sars-cov-2, are, to, a, bat"
1619,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.19047619,"were, at, least, two, zoonotic, of, sars-cov-2, into, humans, from, in, and"
1620,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.19047619,"of, the, lineage, in, geographic, origin, is, and"
1621,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.19047619,"of, from, sars-cov-2, and, at, least, two, zoonotic, in, were, into, humans"
1622,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.19047619,"in, from, of, were, to, sars-cov-2, and, humans"
1623,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.19047619,"the, earliest, covid-19, cases, and, huanan, of, to"
1624,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.19047619,"sars-cov-2, was, from, viruses, that, are, to, and"
1625,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.19047619,"to, humans,, the, sars-cov-2, from, bats, as, intermediate"
1626,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Bats have been reported as being the rich source of 

coronaviruses",0.19047619,"bats, as, the, of"
1627,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","Bats have been reported as being the rich source of 

coronaviruses",0.19047619,"have, been, as, the"
1628,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.19047619,"have, been, a, pangolin, with, to, the, sars-cov-2"
1629,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.19047619,"to, that, sars-cov-2, has, the, virus, of, recombination"
1630,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.19047619,"it, is, that, the, for, sars-cov-2, to, a"
1631,"Bats are natural hosts of many of the known  

coronaviruses",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.19047619,"are, of, the, coronaviruses"
1632,The COVID-19 most likely developed from bat origin coronaviruses,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.19047619,"the, from, bat, coronaviruses"
1633,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.19047619,"that, bat, virus, genome, similarity, of, 96.2%, sars-cov-2"
1634,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.19047619,"an, and, may, have, the, from, or, in"
1635,"atural  

selection in an animal host before zoonotic  

transfer;","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.19047619,"in, animal, host, zoonotic"
1636,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.19047619,"that, the, in, and, transmitted, to, humans, seafood"
1637,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.19047619,"are, and, the, of"
1638,Bats are hosts of many coronaviruses,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.19047619,"bats, are, hosts, of"
1639,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.19047619,"samples, from, the, western, that, of, for, sars-cov-2"
1640,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Bats are natural hosts of many of the known  

coronaviruses",0.19047619,"are, the, natural, of"
1641,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Bats are natural hosts of many of the known  

coronaviruses",0.19047619,"the, of, are, bats"
1642,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Bats are natural hosts of many of the known  

coronaviruses",0.19047619,"the, of, coronaviruses, are"
1643,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.19047619,"the, is, to, be"
1644,"Bats are the second  

largest order of mammals, with over 1,230 species.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.19047619,"are, the, of, with"
1645,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.19047619,"was, the, of, sars-cov-2, to, a, bat, ratg13,"
1646,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.19047619,"were, a, host, for, because, it, with, the"
1647,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.19047619,"with, the, were, a, host, for, because, it"
1648,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.19047619,"of, the, two, in, and, sars-cov-2, sequences, with"
1649,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.19047619,"similarity, sars-cov-2, of, genome, virus, 96.2%, that, bat"
1650,"with the first case being linked to  

a seafood market","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.19047619,"with, the, to, market"
1651,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.19047619,"were, of, sars-cov-2, humans, from, in, and, to"
1652,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.19047619,"the, as, intermediate, host"
1653,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.19047619,"that, of, sars-cov-2, samples, from, the, western, for"
1654,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","Bats are the second  

largest order of mammals, with over 1,230 species.",0.19047619,"with, are, the, of"
1655,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.19047619,"of, the, earliest, covid-19, cases, to, huanan, and"
1656,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","In the 

case of MERS, dromedaries were the principal host.",0.19047619,"in, the, case, of"
1657,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",The COVID-19 most likely developed from bat origin coronaviruses,0.19047619,"the, coronaviruses, from, bat"
1658,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.19047619,"that, the, seafood, in, transmitted, to, humans, and"
1659,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.19047619,"direct, to, humans, can, be, through, and, in"
1660,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.19047619,"in, southern, china, between, august, 2017, and, march, 2019, for, sars-cov-2-like, viruses"
1661,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.19047619,"in, and, can, be, to, humans, through, direct"
1662,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.19047619,"geographic, is, and, origin, of, lineage, the, in"
1663,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.19047619,"and, sars-cov-2-like, viruses, in, southern, china, between, august, 2017, march, 2019, for"
1664,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.19047619,"the, have, from, an, in, or, and, may"
1665,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.19047619,"sars-cov-2, was, identical, to"
1666,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.19047619,"the, to, identical, sars-cov-2"
1667,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.19047619,"are, that, was, sars-cov-2, to, from, and, viruses"
1668,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.19047619,"sars-cov-2, was, to, identical"
1669,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.19047619,"the, that, bats, are, more, hosts, for, than"
1670,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.19047619,"a, it, that, the, sars-cov-2, for, to, is"
1671,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.19047619,"a, the, pangolin, been, to, have, with, sars-cov-2"
1672,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.19047619,"the, sequences, of, two, and, in, with, sars-cov-2"
1673,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.19047619,"is, than, to, sars-cov-2"
1674,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.19047619,"that, sars-cov-2, the, of"
1675,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.19047619,"the, clustering, that, sars-cov-2, are, more, likely, than"
1676,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.19047619,"the, that, sars-cov-2, bat, cov, ratg13, than, pangolin"
1677,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.19047619,"a, are, to, bat, that, the, of, sars-cov-2"
1678,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.19047619,"the, clustering, that, are, more, likely, sars-cov-2, than"
1679,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.19047619,"that, the, sars-cov-2, bat, cov, ratg13, pangolin, than"
1680,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.19047619,"the, sars-cov-2, to, identical"
1681,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.19047619,"the, intermediate, host, as"
1682,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.19047619,"of, to, has, that, sars-cov-2, the, recombination, virus"
1683,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.189655172,"of, cases, covid-19, with, december, early, wuhan, the, huanan, market, in"
1684,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.189655172,"in, the, that, of, positive, environmental, samples, western, from, section, market"
1685,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.189655172,"of, covid-19, cases, in, december, the, huanan, market, with, wuhan, early"
1686,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.189655172,"positive, environmental, samples, from, the, market, western, section, that, of, in"
1687,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.189655172,"all, sars-cov-2, including, the, optimized, rbd, in, coronaviruses, that, of, is"
1688,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.189655172,"coronaviruses, sars-cov-2, in, the, including, all, rbd, that, optimized, is, of"
1689,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.189655172,"two, viruses, of, the, have, in, pangolins, wildlife, guangdong, and, guangxi"
1690,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.189655172,"the, of, and, two, viruses, have, in, guangxi, guangdong, pangolins, wildlife"
1691,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.189655172,"of, shows, to, a, genome, was, previously, obtained, from, found, in"
1692,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.189655172,"a, genome, obtained, from, was, in, shows, to, of, previously, found"
1693,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.189189189,"the, bats, species, to, reservoir, of, and"
1694,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.189189189,"a, of, the, sars-cov-2, genome, that, sars-cov"
1695,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.189189189,"sequence, with, the, sars-cov-2, genome,, in, bat"
1696,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.189189189,"the, sars-cov-2, with, of, genome,, and, to"
1697,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.189189189,"bats, the, hosts, for, sars-cov-2, as, to"
1698,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.189189189,"a, seafood, market, in, wuhan,, to, and"
1699,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.189189189,"the, an, is, to, of, and, coronavirus"
1700,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.189189189,"to, sars-cov-2, is, be, a, and, the"
1701,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.189189189,"the, is, of, spillover, sars-cov-2, to, a"
1702,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.189189189,"the, and, is, of, a, spillover, to"
1703,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.189189189,"the, is, zoonotic, sars-cov-2, due, to, a"
1704,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.189189189,"that, sars-cov-2, genome, to, and, the, of"
1705,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.189189189,"the, of, in, is, to, from, bats"
1706,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.189189189,"that, are, the, sars-cov-2, to, a, bat"
1707,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.189189189,"the, to, that, are, closely, related, in"
1708,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.189189189,"a, to, has, that, the, and, virus"
1709,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.189189189,"is, to, of, an, coronavirus, and, the"
1710,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.189189189,"that, the, virus, of, coronavirus, and, to"
1711,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.189189189,"sars-cov-2, is, to, be, a, and, the"
1712,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.189189189,"is, that, the, virus, was, as, a"
1713,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.189189189,"from, available, bats, to, be, the, virus"
1714,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.189189189,"the, virus, a, that, has, and, to"
1715,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.189189189,"and, that, the, virus, has, to, of"
1716,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.189189189,"to, virus, by, and, available, the, sars-cov-2"
1717,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.189189189,"is, a, virus, that, was, the, as"
1718,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.189189189,"the, virus, is, to, that, of, and"
1719,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.189189189,"the, is, that, virus, to, of, and"
1720,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.189189189,"to, that, the, of, and, is, be"
1721,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.189189189,"the, genomic, analysis, that, sars-cov-2, is, to"
1722,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.189189189,"that, was, first, in, seafood, market, wuhan"
1723,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.189189189,"positive, samples, from, the, market, that, for"
1724,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.189189189,"the, to, from, bats, in, of, is"
1725,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.189189189,"evidence, that, sars-cov-2, is, a, has, animal"
1726,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.189189189,"the, virus, to, that, of, and, coronavirus"
1727,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.189189189,"with, available, genome, the, of, covid-19, virus"
1728,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.189189189,"to, available, be, virus, from, bats, the"
1729,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.189189189,"of, the, genome, covid-19, virus, available, with"
1730,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.189189189,"genomic, analysis, that, sars-cov-2, is, to, the"
1731,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.189189189,"of, to, has, that, the, and, virus"
1732,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.189189189,"to, a, seafood, and, market, in, wuhan,"
1733,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.189189189,"that, seafood, market, in, wuhan, was, first"
1734,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.189189189,"that, the, genome, of, sars-cov-2, a, sars-cov"
1735,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.189189189,"the, bats, most, likely, to, of, intermediate"
1736,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.189189189,"available, to, sars-cov-2, by, the, and, virus"
1737,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.189189189,"the, samples, from, market, positive, for, that"
1738,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.189189189,"sars-cov-2, is, to, a, spillover, of, the"
1739,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.189189189,"due, to, the, a, sars-cov-2, is, zoonotic"
1740,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.189189189,"bats, of, and, species, to, the, reservoir"
1741,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.189189189,"bats, to, the, most, likely, of, intermediate"
1742,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.189189189,"in, related, that, the, are, closely, to"
1743,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.189189189,"is, to, a, spillover, of, and, the"
1744,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.189189189,"with, the, genome,, sars-cov-2, bat, in, sequence"
1745,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.189189189,"that, bats, the, reservoir, hosts, for, of"
1746,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.189189189,"we, believe, that, sars-cov-2, is, of, the"
1747,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.189189189,"analysis, of, covid-19, that, most, the, bat"
1748,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.189189189,"analysis, that, the, of, most, bat, covid-19"
1749,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.189189189,"the, of, this, indicates, that, is, a"
1750,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.189189189,"of, sars-cov-2, with, bat, ratg13, genome, than"
1751,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.189189189,"is, that, the, and, be, of, to"
1752,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.189189189,"sars-cov-2, that, bats, are, probable, hosts, for"
1753,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.189189189,"to, the, sars-cov-2, bats, as, hosts, for"
1754,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.189189189,"a, are, to, bat, that, the, sars-cov-2"
1755,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.189189189,"that, sars-cov-2, are, similar, to, a, the"
1756,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.189189189,"we, sars-cov-2, the, believe, that, of, is"
1757,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.189189189,"that, bats, are, probable, hosts, for, sars-cov-2"
1758,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.189189189,"the, that, sars-cov-2, with, bat, cov, ratg13"
1759,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.189189189,"this, that, sars-cov-2, the, bats, origin, of"
1760,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.189189189,"sars-cov-2, sequences, pangolin, and, the, origin, of"
1761,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.189189189,"the, genome, of, sars-cov-2, that, and, to"
1762,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.189189189,"that, are, the, sars-cov-2, similar, to, a"
1763,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.189189189,"the, sars-cov-2, sequences, and, pangolin, origin, of"
1764,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.189189189,"of, bat, genome, with, sars-cov-2, than, ratg13"
1765,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.189189189,"that, sars-cov-2, the, with, bat, cov, ratg13"
1766,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.189189189,"the, of, that, bats, reservoir, hosts, for"
1767,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.189189189,"with, the, and, genome,, sars-cov-2, to, of"
1768,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.189189189,"this, that, bats, the, origin, of, sars-cov-2"
1769,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.189189189,"evidence, that, sars-cov-2, has, a, animal, is"
1770,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.189189189,"this, indicates, a, that, the, is, of"
1771,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.188679245,"the, that, in, a, to, two, spillover, from, animals, humans"
1772,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.188679245,"from, in, humans, two, the, that, a, animals, to, spillover"
1773,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.188679245,"coronavirus, from, a, malayan, pangolin, with, sars-cov-2, has, to, the"
1774,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.188679245,"two, banal, closely, related, to, and, a, at, the, which"
1775,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.188679245,"a, two, closely, related, banal, and, which, to, at, the"
1776,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.188679245,"is, not, a, which, the, ratg13,, in, its, spike, from"
1777,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.188679245,"a, coronavirus, from, the, malayan, pangolin, has, to, with, sars-cov-2"
1778,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.188679245,"ratg13,, from, a, is, its, spike, in, the, which, not"
1779,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.188679245,"the, rbd, also, in, to, bind, ace2, receptors, these, of"
1780,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.188679245,"is, similarity, sars-cov-2, and, ratg13, to, the, between, viruses, in"
1781,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.188679245,"one, that, with, the, of, pangolin, may, have, to, intermediate"
1782,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.188679245,"and, similarity, between, sars-cov-2, ratg13, in, is, the, viruses, to"
1783,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.188679245,"rbd, of, also, to, bind, ace2, receptors, the, in, these"
1784,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.188679245,"that, may, have, of, pangolin, with, one, to, the, intermediate"
1785,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.1875,"the, virus, have, into, human, from, to, and, may"
1786,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.1875,"did, a, that, the, virus, was, released, had, by"
1787,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.1875,"that, sars-cov-2, is, a, naturally, virus"
1788,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.1875,"identified, the, to, have, with, sars-cov-2"
1789,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.1875,"the, sars-cov-2, is, in, of, bat"
1790,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.1875,"the, genome, of, sars-cov-2, to, bat"
1791,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.1875,"is, the, to, sars-cov-2, known, in"
1792,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",hese reservoirs are the bats,0.1875,"bats, the, reservoirs"
1793,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.1875,"a, that, the, also, ace2, receptor, and, for, entry, to, host, is"
1794,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.1875,"the, is, considered, to, and, human"
1795,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.1875,"the, of, sars-cov-2, and, is, to"
1796,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.1875,"is, believed, the, sars-cov-2, to, a"
1797,Bats are hosts of many coronaviruses,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.1875,"bats, hosts, of"
1798,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.1875,"is, the, sars-cov-2, to, a, coronavirus."
1799,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.1875,"the, sars-cov-2, is, bat, in, of"
1800,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.1875,"are, and, the, transmitted, bats, to"
1801,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.1875,"the, that, zoonotic, origin, by, a"
1802,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.1875,"that, was, released, a, by, had, the, virus, did"
1803,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.1875,"a, from, to, humans, the, spillover"
1804,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.1875,"of, the, hypothesis, that, sars-cov-2, a"
1805,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.1875,"susceptible, to, sars-cov-2, sold, and, the"
1806,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.1875,"other, closely, related, to, in, more, than, these, the"
1807,hese close genetic relations suggest that they all have their ecological origin in bat populations,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.1875,"that, all, have, their, origin, in"
1808,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.1875,"have, identified, sars-cov-2, to, with, the"
1809,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.1875,"is, the, to, human, and, considered"
1810,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.1875,"the, of, to, bat, is, hosts"
1811,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.1875,"the, are, bats, and, transmitted, to"
1812,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.1875,"the, virus, and, to, in, china"
1813,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.1875,"in, the, a, was, and, market"
1814,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.1875,"the, virus, and, to, were, in"
1815,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.1875,"the, virus, animal, in, to, and"
1816,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.1875,"is, that, the, had, similar, to"
1817,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.1875,"the, to, sars-cov, and, mers-cov, in"
1818,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.1875,"of, the, sequence, that, and, is"
1819,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.1875,"the, of, and, to, is, that"
1820,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.1875,"is, believed, that, bats, the, to"
1821,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.1875,"the, sars-cov-2, to, bat, of, genome"
1822,The FCS of SARS-CoV-2 was not bioengineered—full stop.,"According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.1875,"the, of, sars-cov-2"
1823,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.1875,"also, a, for, the, is, and, that, to, ace2, receptor, entry, host"
1824,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.1875,"to, the, a, spillover, humans, from"
1825,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.1875,"all, that, have, their, origin, in"
1826,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.1875,"to, have, the, and, into, may, from, virus, human"
1827,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.1875,"the, virus, to, and, in, animal"
1828,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.1875,"the, virus, from, market, to, human"
1829,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.1875,"that, and, the, virus, features, of"
1830,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.1875,"analysis, the, covid-19, virus, in, and, december, of, 2019"
1831,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.1875,"coronavirus, the, that, similar, to, of"
1832,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.1875,"similar, to, that, of, sars-cov-2, the"
1833,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.1875,"analysis, of, the, that, sars-cov-2, a"
1834,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.1875,"the, of, sars-cov-2, with, and, sars-cov"
1835,Bats are hosts of many coronaviruses,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.1875,"are, hosts, of"
1836,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.1875,"bats, of, are, to, be, the"
1837,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.1875,"of, the, that, coronavirus, similar, to"
1838,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.1875,"the, hypothesis, that, sars-cov-2, a, of"
1839,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.1875,"a, analysis, of, the, sars-cov-2, that"
1840,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.1875,"for, and, to, the, zoonotic, of"
1841,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.1875,"for, and, in, the, of, sars-cov-2"
1842,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.1875,"the, is, similar, to, that, had"
1843,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.1875,"sars-cov-, 2, been, by, virus, to, and, the, sars-cov-2"
1844,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.1875,"the, to, that, related, sars-cov-2, in"
1845,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.1875,"of, virus, that, it, is, to, the, and, for"
1846,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.1875,"of, bat, genome, similarity, with, sars-cov-2"
1847,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.1875,"the, virus, human, from, market, to"
1848,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.1875,"the, origin, by, a, zoonotic, that"
1849,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.1875,"is, that, the, and, of, sequence"
1850,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.1875,"from, a, to, an, intermediate, host"
1851,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.1875,"the, sold, to, susceptible, sars-cov-2, and"
1852,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.1875,"for, that, in, the, of, sars-cov-2"
1853,hese reservoirs are the bats,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.1875,"reservoirs, the, bats"
1854,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.1875,"the, that, in, related, to, sars-cov-2"
1855,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.1875,"and, the, virus, to, in, china"
1856,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.1875,"the, were, to, virus, in, and"
1857,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.1875,"is, that, the, and, of, to"
1858,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.1875,"the, known, sars-cov-2, is, to, in"
1859,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.1875,"these, in, more, closely, related, to, the, than, other"
1860,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.1875,"in, the, of, palm, civets, as, sars, was, a, at, found, that, virus, from, infected, were, to, and, closely, related, than"
1861,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.1875,"in, than, the, sars, of, from, found, that, palm, civets, as, at, virus, was, to, were, infected, a, closely, related, and"
1862,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.1875,"the, covid-19, is, to, seafood, market"
1863,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.1875,"the, is, to, of, hosts, bat"
1864,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.1875,"this, that, natural, selection, in, pangolin, the, for, of"
1865,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.1875,"the, to, mers-cov, and, sars-cov, in"
1866,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.1875,"analysis, of, the, covid-19, virus, in, december, 2019, and"
1867,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",Bats are hosts of many coronaviruses,0.1875,"of, are, hosts"
1868,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.1875,"the, covid-19, seafood, market, is, to"
1869,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.1875,"the, of, virus, for, it, is, to, that, and"
1870,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.1875,"the, was, that, bat, for, sars-cov-2."
1871,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.1875,"and, the, was, a, market, in"
1872,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.1875,"sars-cov-2, is, a, virus, that, naturally"
1873,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.1875,"to, the, for, zoonotic, and, of"
1874,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.1875,"a, from, an, intermediate, host, to"
1875,"According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.1875,"the, sars-cov-2, of"
1876,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.1875,"the, sars-cov-2, to, bat, cov, genome"
1877,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.1875,"bat, genome, similarity, of, with, sars-cov-2"
1878,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.1875,"the, results, obtained, using, clustering, and, to, that, sars-cov-2, bat, pangolin, cluster"
1879,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.1875,"sars-cov-2, is, believed, to, a, the"
1880,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.1875,"to, the, a, sars-cov-2, is, coronavirus."
1881,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.1875,"is, believed, that, the, bats, to"
1882,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.1875,"to, that, the, bats, as, hosts, for, are, sars-cov-2"
1883,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.1875,"are, in, that, pangolins, could, be, possible, hosts, for"
1884,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.1875,"to, virus, sars-cov-, 2, been, by, and, the, sars-cov-2"
1885,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.1875,"that, pangolins, could, be, possible, hosts, for, are, in"
1886,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.1875,"this, is, we, sars-cov-2, bat, cov, ratg13, the, that"
1887,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.1875,"this, bat, cov, ratg13, is, the, sars-cov-2, we, that"
1888,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.1875,"the, results, obtained, using, clustering, that, sars-cov-2, to, cluster, bat, and, pangolin"
1889,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.1875,"that, bats, are, the, hosts, for, sars-cov-2, as, to"
1890,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.1875,"the, sars-cov-2, genome, to, bat, cov"
1891,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.1875,"of, the, sars-cov-2, with, sars-cov, and"
1892,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.1875,"sars-cov-2, the, for, in, and, of"
1893,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.1875,"the, that, of, in, for, sars-cov-2"
1894,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.1875,"that, the, virus, features, of, and"
1895,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.1875,"pangolin, in, the, this, that, for, of, natural, selection"
1896,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.1875,"that, the, bat, for, was, sars-cov-2."
1897,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.1875,"of, the, that, sars-cov-2, similar, to"
1898,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.186813187,"feed, on, and, can, also, bats., species, are, known, to, or, dying, bats, cave, may, be, by"
1899,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.186813187,"or, dying, bats, on, cave, can, be, by, bats., species, are, known, to, and, may, also, feed"
1900,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.186440678,"the, that, of, cases, with, huanan, market, and, lineage, in, at"
1901,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.186440678,"and, a, of, sars-cov-2, in, is, the, for, to, human, 2"
1902,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.186440678,"sars-cov-2, from, of, sequences, in, rhinolophus, the, and, with, sars-cov-2-related, coronaviruses"
1903,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.186440678,"the, sequences, of, sars-cov-2-related, coronaviruses, from, rhinolophus, and, in, with, sars-cov-2"
1904,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.186440678,"the, of, with, lineage, and, cases, huanan, market, that, at, in"
1905,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.186440678,"genome, obtained, from, in, wuhan, china, the, of, virus, covs, previously"
1906,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.186440678,"in, the, of, for, 2, is, to, sars-cov-2, human, and, a"
1907,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.186440678,"provide, evidence, to, that, the, bats, and, pangolins, hosts, for, are"
1908,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.186440678,"are, to, the, and, provide, evidence, that, bats, pangolins, hosts, for"
1909,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.186440678,"genome, obtained, from, in, wuhan, china, the, virus, of, covs, previously"
1910,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.186046512,"the, of, is, identical, to, sars-cov-2, that, cov"
1911,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.186046512,"covid-19, virus, that, to, the, bat, and, was"
1912,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.186046512,"that, in, were, exposed, market, wuhan, city,, on"
1913,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.186046512,"the, genome, of, is, 80%, to, bat, sars-cov"
1914,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.186046512,"of, the, earliest, covid-19, cases, to, were, huanan"
1915,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.186046512,"the, and, genome, sequence, 96.2%, to, that, bat"
1916,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.186046512,"of, the, covid-19, cases, in, with, huanan, market"
1917,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.186046512,"that, has, the, of, virus, genome,, and, to"
1918,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.186046512,"the, genetic, sars-cov-2, and, of, virus, to, that"
1919,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.186046512,"the, genome, of, 80%, sars-cov, is, to, bat"
1920,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.186046512,"the, genome, to, bat, and, that, sequence, 96.2%"
1921,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.186046512,"of, genetic, to, that, sars-cov-2, the, and, virus"
1922,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.186046512,"on, that, were, exposed, market, in, wuhan, city,"
1923,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.186046512,"of, the, earliest, covid-19, cases, were, to, huanan"
1924,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.186046512,"of, covid-19, cases, in, the, huanan, market, with"
1925,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.186046512,"discovered, in, other, closely, related, and, to, the"
1926,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.186046512,"the, and, other, closely, related, to, discovered, in"
1927,"Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.186046512,"based, on, the, large, of, infected, that, were, to, wet, animal, market, in, china,, is, likely"
1928,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.186046512,"the, to, in, wet, of, based, large, china,, is, on, likely, that, infected, were, animal, market"
1929,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.186046512,"virus, the, covid-19, was, to, bat, and, that"
1930,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.186046512,"that, sars-cov-2, also, to, pangolin, and, a, the"
1931,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.186046512,"the, that, sars-cov-2, to, a, also, and, pangolin"
1932,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.186046512,"the, of, pangolin-cov, to, sars-cov-2, at, that, virus"
1933,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.186046512,"that, the, of, sars-cov-2, is, identical, to, cov"
1934,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.186046512,"the, that, sars-cov-2, at, of, virus, to, pangolin-cov"
1935,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.185714286,"the, that, of, known, covid-19, cases, associated, with, huanan, seafood, and, these, collected"
1936,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.185714286,"collected, of, the, that, covid-19, cases, and, these, associated, with, huanan, seafood, known"
1937,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.185714286,"bat, sars, cov, and, the, are, divided, into, 2, clusters, while, cluster, with"
1938,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.185714286,"while, the, bat, cov, and, are, divided, into, clusters, cluster, 2, with, sars"
1939,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.18556701,"and, the, of, also, to, are, as, a, bats, with, that, into, in, for, recombination, can, virus, is"
1940,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.18556701,"bats, are, also, a, for, as, the, recombination, of, is, virus, can, and, in, with, that, to, into"
1941,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.185185185,"the, of, are, animal, and"
1942,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.185185185,"bat, is, closer, to, sars-cov-2"
1943,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.185185185,"is, to, be, a, of, an, coronavirus, and, the, ability"
1944,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.185185185,"a, coronavirus, the, of, is, and, be, ability, to, an"
1945,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.185185185,"is, sars-cov-2, of, a, coronavirus"
1946,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.185185185,"bats, of, and, be, the"
1947,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.185185185,"the, and, other, to, in"
1948,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.185185185,"the, that, is, in, sars-cov-2"
1949,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.185185185,"the, of, sars, outbreak, bats"
1950,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.185185185,"bats, to, and, be, the"
1951,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.185185185,"was, that, of, sars-cov-2, the"
1952,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.185185185,"there, is, evidence, that, a"
1953,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.185185185,"from, virus, that, is, this"
1954,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.185185185,"the, intermediate, host, as, to"
1955,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","Bats have been reported as being the rich source of 

coronaviruses",0.185185185,"have, been, of, coronaviruses, as"
1956,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.185185185,"sars-cov-2, has, similarity, to, with"
1957,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.185185185,"sars-cov-2, isolated, from, bat, the"
1958,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.185185185,"the, of, to, human, bat"
1959,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.185185185,"human, to, and, intermediate, hosts"
1960,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.185185185,"the, of, is, and, to"
1961,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.185185185,"a, from, was, market, in, china, the, virus, to, bats"
1962,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.185185185,"is, that, the, and, animal"
1963,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.185185185,"animal, to, and, in, the"
1964,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.185185185,"is, the, virus, to, in"
1965,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.185185185,"the, is, and, to, sars-cov"
1966,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.185185185,"that, the, may, be, of"
1967,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.185185185,"the, to, of, bat, human"
1968,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.185185185,"to, intermediate, hosts, and, human"
1969,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.185185185,"the, a, spillover, from, to"
1970,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.185185185,"the, isolated, from, bat, sars-cov-2"
1971,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.185185185,"of, the, outbreak, sars, bats"
1972,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.185185185,"the, is, in, related, to"
1973,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.185185185,"the, is, and, that, animal"
1974,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.185185185,"genome, between, and, with, the, of, virus, isolated, from, in"
1975,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.185185185,"viruses, that, are, to, and"
1976,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.185185185,"genome, of, the, virus, isolated, from, in, with, between, and"
1977,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.185185185,"that, from, this, virus, is"
1978,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.185185185,"of, and, are, the, animal"
1979,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","Bats are natural hosts of many of the known  

coronaviruses",0.185185185,"bats, are, of, the, coronaviruses"
1980,"Bats have been reported as being the rich source of 

coronaviruses","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.185185185,"have, been, as, of, coronaviruses"
1981,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.185185185,"the, that, sars-cov-2, is, in"
1982,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.185185185,"the, in, is, related, to"
1983,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.185185185,"the, that, is, not, any"
1984,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.185185185,"this, is, within, the, with, sars-cov-2, that, more, for, than"
1985,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.185185185,"sars-cov-2, genome, found, 96.2%, bat"
1986,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.185185185,"the, sars-cov-2, that, is, to"
1987,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","bats are also important reservoir species for a great 

range of coronaviruses",0.185185185,"bats, are, reservoir, for, a"
1988,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.185185185,"the, intermediate, host, to, as"
1989,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.185185185,"a, from, to, the, spillover"
1990,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.185185185,"the, to, and, in, animal"
1991,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.185185185,"the, in, and, to, other"
1992,all three BANAL series viruses also use ACE2 as an entry receptor.,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.185185185,"three, banal, series, viruses, also"
1993,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.185185185,"the, virus, is, to, in"
1994,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.185185185,"our, that, sars-cov-2, is, a"
1995,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.185185185,"sars-cov-2, is, a, of, coronavirus"
1996,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",The COVID-19 most likely developed from bat origin coronaviruses,0.185185185,"the, covid-19, from, most, likely"
1997,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.185185185,"to, humans, direct, and, be"
1998,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.185185185,"the, bats, and, be, to"
1999,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.185185185,"and, be, to, humans, direct"
2000,The COVID-19 most likely developed from bat origin coronaviruses,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.185185185,"the, covid-19, most, likely, from"
2001,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.185185185,"bat, found, genome, 96.2%, sars-cov-2"
2002,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.185185185,"are, viruses, to, that, and"
2003,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.185185185,"evidence, for, and, that, sars-cov-2"
2004,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.185185185,"the, virus, was, from, bats, to, a, market, in, china"
2005,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.185185185,"that, is, the, most, sars-cov-2"
2006,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.185185185,"sars-cov-2, is, closer, to, bat"
2007,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.185185185,"sars-cov-2, bat, ratg13, pangolin, to"
2008,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.185185185,"the, of, sars-cov-2, that, is"
2009,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.185185185,"the, for, more, than, is, that, sars-cov-2, with, this, within"
2010,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.185185185,"has, to, similarity, with, sars-cov-2"
2011,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.185185185,"the, is, to, of, and"
2012,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.185185185,"the, is, to, and, sars-cov"
2013,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.185185185,"evidence, that, and, for, sars-cov-2"
2014,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.185185185,"the, for, sars-cov-2, intermediate, host"
2015,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.185185185,"is, that, the, most, sars-cov-2"
2016,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.185185185,"that, sars-cov-2, was, the, of"
2017,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.185185185,"bat, ratg13, to, sars-cov-2, pangolin"
2018,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.184615385,"sars-cov-2, a, between, and, coronaviruses, from, bat, species, as, high, to, in"
2019,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.184615385,"sars-cov-2, from, to, a, as, high, between, and, coronaviruses, in, bat, species"
2020,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.184615385,"in, the, and, to, that, sars-cov-2, is, bat, cov, ratg13, guangdong, pangolin"
2021,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.184615385,"is, sars-cov-2, and, bat, cov, ratg13, guangdong, pangolin, to, the, that, in"
2022,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.184210526,"sars-cov-2, to, are, closely, related, coronaviruses, bat"
2023,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.184210526,"in, sequences, and, have, similar, to, sars-cov-2."
2024,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.184210526,"coronaviruses, are, viruses, to, the, that, and"
2025,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.184210526,"that, the, genome, sars-cov-2, identical, to, bat"
2026,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.184210526,"that, sars-cov-2, to, identical, genome, bat, the"
2027,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.184210526,"ratg13,, was, found, the, 96.2%, identity, genome"
2028,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.184210526,"suggesting, sars-cov-2, might, virus, the, and, cov"
2029,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.184210526,"of, the, to, bat, sars-like, covs, and"
2030,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.184210526,"the, that, animal, be, origin, of, zoonosis"
2031,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.184210526,"and, the, virus, was, to, a, in"
2032,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.184210526,"virus, that, is, to, the, and, was"
2033,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.184210526,"that, sars-cov-2, the, with, of, and, to"
2034,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.184210526,"has, found, the, of, to, sars-cov-2, in"
2035,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.184210526,"a, to, that, the, of, sars-cov-2, from"
2036,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.184210526,"to, the, that, sars-cov-2, a, of, from"
2037,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.184210526,"a, that, the, two, lineage, are, to"
2038,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.184210526,"of, be, to, the, huanan, that, transmission"
2039,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.184210526,"that, sars-cov-2, are, to, and, the, of"
2040,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.184210526,"a, are, two, to, that, the, lineage"
2041,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.184210526,"more, the, earliest, cases, to, huanan, that"
2042,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.184210526,"that, the, earliest, cases, more, to, huanan"
2043,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.184210526,"virus, that, to, the, bat, and, was"
2044,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.184210526,"all, that, have, different, animals,, infect, and"
2045,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.184210526,"all, have, that, infect, different, animals,, and"
2046,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.184210526,"studies, that, genome, to, and, a, the"
2047,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.184210526,"data, genetic, and, that, by, recombination, of"
2048,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.184210526,"genetic, and, that, a, of, the, virus"
2049,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.184210526,"that, sars-cov-2, to, and, a, the, of"
2050,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.184210526,"the, between, and, of, is, to, bat"
2051,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.184210526,"studies, have, shown, that, genes, to, sars-cov-2"
2052,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.184210526,"a, the, to, in, virus, and, was"
2053,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.184210526,"the, virus, from, in, market, to, and"
2054,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.184210526,"the, to, possibly, was, transmitted, from, bats"
2055,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.184210526,"its, in, the, that, to, similar, virus"
2056,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.184210526,"results, that, might, be, the, hosts, for"
2057,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.184210526,"the, is, to, of, between, bat, and"
2058,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.184210526,"studies, genes, have, shown, that, sars-cov-2, to"
2059,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.184210526,"of, genetic, data, that, by, recombination, and"
2060,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.184210526,"is, a, virus, humans, to, the, for"
2061,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.184210526,"sars-cov-2, are, closely, related, to, bat, coronaviruses"
2062,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.184210526,"and, the, virus, from, to, market, in"
2063,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.184210526,"humans, is, that, the, and, sars-cov-2, infected"
2064,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.184210526,"that, sars-cov-2, is, very, likely, to, be"
2065,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.184210526,"of, the, coronavirus, and, identity, with, bat"
2066,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.184210526,"coronavirus, strain, the, with, genome, was, of"
2067,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.184210526,"the, viruses, and, are, coronaviruses, that, to"
2068,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.184210526,"the, results, of, that, sars-cov-2, genomes, to"
2069,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.184210526,"of, the, and, with, bat, coronavirus, identity"
2070,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.184210526,"of, the, novel, virus, revealed, covid-19, and"
2071,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.184210526,"and, revealed, the, novel, covid-19, virus, of"
2072,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.184210526,"that, sars-cov-2, genome, and, a, the, of"
2073,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.184210526,"of, the, genome, was, with, coronavirus, strain"
2074,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.184210526,"the, of, that, to, a, with, genome"
2075,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.184210526,"the, huanan, that, to, be, of, transmission"
2076,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.184210526,"the, covid-19, huanan, seafood, market, is, to"
2077,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.184210526,"the, origin, of, zoonosis, be, that, animal"
2078,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.184210526,"that, in, pangolin, and, the, for, of"
2079,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.184210526,"sars-cov-2, from, malayan, pangolins, and, of, as"
2080,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.184210526,"the, virus, similar, to, that, its, in"
2081,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.184210526,"of, covid-19, that, is, similar, to, the"
2082,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.184210526,"the, sars-cov-2, has, to, in, of, found"
2083,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.184210526,"to, humans, is, between, and, be, the"
2084,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.184210526,"is, that, sars-cov-2, the, and, infected, humans"
2085,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.184210526,"for, the, of, raccoon, and, civets, were, species, that, virus, collected, from, palm, a, only, found, in, sars, evidence, as, to"
2086,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.184210526,"in, the, sars, of, from, found, that, palm, civets, for, as, only, raccoon, virus, collected, to, species, were, a, and, evidence"
2087,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.184210526,"covid-19, is, to, the, huanan, seafood, market"
2088,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.184210526,"a, virus, to, humans, for, the, is"
2089,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.184210526,"results, of, the, in, and, a, viruses"
2090,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.184210526,"in, this, can, that, the, an, of"
2091,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.184210526,"the, to, covid-19, which, from, wild, animals"
2092,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.184210526,"suggests, that, in, and, the, virus, of"
2093,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.184210526,"is, the, to, that, virus, and, was"
2094,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.184210526,"the, virus, was, that, bat, and, to"
2095,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.184210526,"is, that, the, of, similar, to, covid-19"
2096,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.184210526,"the, that, evolutionary, of, virus, and, to"
2097,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.184210526,"the, to, be, is, humans, and, between"
2098,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.184210526,"the, from, covid-19, to, which, wild, animals"
2099,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.184210526,"a, of, genetic, that, the, and, virus"
2100,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.184210526,"the, results, for, that, might, be, hosts"
2101,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.184210526,"the, and, to, sars-like, bat, covs, of"
2102,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.184210526,"the, sars-cov-2, sequences, probable, bat, origin, of"
2103,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.184210526,"in, have, sequences, similar, to, and, sars-cov-2."
2104,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.184210526,"a, of, viruses, in, and, results, the"
2105,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.184210526,"we, between, and, that, in, the, sars-cov-2"
2106,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.184210526,"sars-cov-2, and, bat, ratg13, pangolin, similarity, the"
2107,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.184210526,"probable, bat, origin, of, sars-cov-2, sequences, the"
2108,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.184210526,"the, that, are, to, sars-cov-2, and, of"
2109,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.184210526,"studies, the, genome, to, and, that, a"
2110,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.184210526,"a, of, to, that, sars-cov-2, the, and"
2111,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.184210526,"a, of, the, sars-cov-2, genome, that, and"
2112,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.184210526,"studies, that, are, the, a, of, and"
2113,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.184210526,"sars-cov-2, and, pangolin, to, the, of, sars-cov-2."
2114,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.184210526,"results, of, the, that, sars-cov-2, to, genomes"
2115,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.184210526,"a, the, with, genome, that, to, of"
2116,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.184210526,"we, sars-cov-2, and, the, between, that, in"
2117,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.184210526,"studies, that, are, and, a, the, of"
2118,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.184210526,"the, pangolin, in, and, that, for, of"
2119,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.184210526,"suggests, that, the, virus, in, and, of"
2120,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.184210526,"evolutionary, of, virus, that, to, the, and"
2121,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.184210526,"the, in, of, an, that, can, this"
2122,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.184210526,"the, was, transmitted, from, bats, to, possibly"
2123,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.184210526,"is, very, likely, that, sars-cov-2, to, be"
2124,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.184210526,"virus, the, cov, and, suggesting, sars-cov-2, might"
2125,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.184210526,"was, found, the, genome, 96.2%, ratg13,, identity"
2126,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.184210526,"of, sars-cov-2, as, from, malayan, pangolins, and"
2127,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.184210526,"the, similarity, sars-cov-2, and, bat, ratg13, pangolin"
2128,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.184210526,"sars-cov-2, to, pangolin, and, the, of, sars-cov-2."
2129,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.183673469,"a, is, the, that, in, had, sequence, virus, was"
2130,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.183673469,"no, virus, highly, had, by, any, was, the, sars-cov-2"
2131,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.183673469,"is, that, was, a, had, the, virus, sequence, in"
2132,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.183673469,"in, the, virus, is, to, that, human, and, a"
2133,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.183673469,"from, humans, the, of, that, a, sars-cov-2, to, spillover"
2134,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.183673469,"the, that, huanan, market, and, genomic, within, in, at"
2135,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.183673469,"to, the, that, sars-cov-2, a, of, spillover, humans, from"
2136,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.183673469,"of, a, that, the, virus, to, which, bat, and"
2137,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.183673469,"from, to, a, coronavirus, malayan, pangolin, with, sars-cov-2, the"
2138,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.183673469,"a, of, the, has, by, that, data, to, virus"
2139,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.183673469,"is, similarity, sars-cov-2, and, bat, to, the, between, that"
2140,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.183673469,"the, of, is, identical, to, sars-cov-2, that, new, virus"
2141,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.183673469,"the, of, from, and, in, identity, with, sars-cov-2, genome"
2142,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.183673469,"has, genome, sequence, identity, with, bat, and, sars-cov-2, a"
2143,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.183673469,"highly, sars-cov-2, was, by, no, had, the, virus, any"
2144,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.183673469,"a, is, the, to, that, in, human, virus, and"
2145,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.183673469,"the, that, sars-cov-2, has, with, of, virus, and, to"
2146,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.183673469,"a, coronavirus, from, the, malayan, pangolin, to, with, sars-cov-2"
2147,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.183673469,"genome, identity, sars-cov-2, and, with, the, of, from, in"
2148,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.183673469,"of, southeast, asia, and, are, species, living, in, the"
2149,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.183673469,"discovered, in, closely, related, and, are, to, sars-cov-2, the"
2150,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.183673469,"the, are, species, of, living, in, southeast, asia, and"
2151,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.183673469,"the, discovered, to, are, closely, related, sars-cov-2, in, and"
2152,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.183673469,"the, genomic, within, at, huanan, market, that, in, and"
2153,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.183673469,"human, that, a, natural, of, the, is, most, likely"
2154,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.183673469,"sars-cov-2, some, pangolin, coronaviruses, exhibit, similarity, to, the, of"
2155,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.183673469,"genome, has, a, sequence, identity, sars-cov-2, and, with, bat"
2156,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.183673469,"a, of, data, to, has, that, by, the, virus"
2157,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.183673469,"the, of, human, is, most, likely, natural, a, that"
2158,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.183673469,"this, to, that, the, scenario, origin, and, is, be"
2159,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.183673469,"is, to, origin, the, that, and, this, scenario, be"
2160,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.183673469,"that, the, bats, hosts, for, are, more, than, pangolins."
2161,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.183673469,"the, virus, a, of, which, to, that, and, bat"
2162,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.183673469,"the, similarity, between, sars-cov-2, and, is, to, that, bat"
2163,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.183673469,"bat, cov, have, the, same, sars-cov-2, with, ratg13, guangdong"
2164,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.183673469,"sars-cov-2, have, the, same, with, bat, cov, ratg13, guangdong"
2165,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.183673469,"the, that, bats, are, more, hosts, for, than, pangolins."
2166,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.183673469,"have, that, bats, are, the, hosts, for, of, and"
2167,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.183673469,"that, the, of, bats, and, have, hosts, for, are"
2168,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.183673469,"the, of, virus, to, that, sars-cov-2, has, with, and"
2169,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.183673469,"the, sars-cov-2, of, new, virus, is, identical, to, that"
2170,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.183673469,"some, pangolin, coronaviruses, exhibit, similarity, to, sars-cov-2, the, of"
2171,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.183333333,"of, the, that, covid-19, cases, were, and, half, huanan, market,, earliest"
2172,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.183333333,"sars-cov-2, is, sequence, between, and, bat, et, al.,, to, 96.2%, that"
2173,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.183333333,"between, sars-cov-2, and, et, al.,, sequence, is, 96.2%, to, that, bat"
2174,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.183333333,"study, found, that, with, the, of, pangolin, to, an, intermediate, host"
2175,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.183333333,"to, based, on, the, in, and, that, pangolins, be, hosts, for"
2176,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.183333333,"half, of, the, earliest, covid-19, cases, were, huanan, market,, and, that"
2177,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.183333333,"the, earliest, known, covid-19, cases, and, huanan, market, of, a, to"
2178,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.183333333,"of, cases, covid-19, a, to, and, the, huanan, market, earliest, known"
2179,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.183333333,"suggest, that, have, been, by, a, of, virus, to, are, the"
2180,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.183333333,"a, of, the, been, are, by, that, suggest, have, to, virus"
2181,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.183333333,"that, and, be, hosts, for, to, pangolins, based, on, the, in"
2182,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.183333333,"study, that, of, to, an, intermediate, host, found, pangolin, with, the"
2183,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.181818182,"viruses, and, are, bat, coronaviruses, many, to, human"
2184,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.181818182,"sars-cov-2, genome, to, identical"
2185,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.181818182,"genetic, been, of, the, systems, would, have, used"
2186,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.181818182,"human, and, are, to, bat, coronaviruses, many, viruses"
2187,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.181818182,"and, that, the, covid-19, virus, identity, to, bat"
2188,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.181818182,"virus, sequence, that, 96.2%, identity, the, sars-cov-2, bat"
2189,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.181818182,"the, showed, identity, to, suggesting, that, sars-cov-2, was"
2190,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.181818182,"to, the, sequence, with, sars-cov-2, is"
2191,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.181818182,"is, the, and, of, sequence, to"
2192,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.181818182,"the, genome, of, is, to, sars-like, bat, sars-cov"
2193,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.181818182,"of, sars-cov-2, are, to"
2194,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.181818182,"in, the, case, of, favored, as"
2195,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.181818182,"in, the, case, of, covid-19,, a"
2196,"Bats have been reported as being the rich source of 

coronaviruses","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.181818182,"bats, have, been, as, the, of"
2197,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.181818182,"the, was, in, bats,, and, to"
2198,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.181818182,"the, virus, and, to, discovered, in"
2199,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.181818182,"the, spillover, from, intermediate, as, to"
2200,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.181818182,"that, the, covid-19, in, to, wuhan, china,, of"
2201,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.181818182,"the, covid-19, is, to, in, market"
2202,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.181818182,"the, and, sars-cov-2, is, to, of"
2203,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.181818182,"to, the, sars-cov-2, a, of, spillover"
2204,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.181818182,"is, a, spillover, an, animal, to"
2205,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.181818182,"a, of, to, sars-cov-2, the, and"
2206,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.181818182,"the, of, hosts, and"
2207,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.181818182,"natural, the, of, sars-, and, be"
2208,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.181818182,"the, reservoirs, are, of, bats, and"
2209,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.181818182,"the, of, sars-cov-2, identity, with, sars-cov"
2210,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",Bats are likely reservoir hosts for SARS-CoV-2,0.181818182,"bats, are, likely, hosts"
2211,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.181818182,"with, the, sars-cov-2, is, to, sequence"
2212,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.181818182,"to, the, sars-cov-2, a, from, origin"
2213,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.181818182,"the, to, coronavirus, sequence, a, high"
2214,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.181818182,"the, to, in, bats,, and, was"
2215,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.181818182,"analysis, of, that, is, the, bat"
2216,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.181818182,"of, the, that, sars-cov-2, is, to"
2217,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.181818182,"of, the, and, identity, with, bat"
2218,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.181818182,"the, with, genome, that, to, of"
2219,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.181818182,"the, of, to, sars-cov-2, transmitted, bats"
2220,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","with the first case being linked to  

a seafood market",0.181818182,"a, the, to, with"
2221,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.181818182,"the, of, sars-cov-2, this, has, been, from, bats"
2222,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.181818182,"a, identified, from, been, to, have, similarity, sars-cov-2"
2223,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.181818182,"sars-cov-2, to, a, spillover, of, the"
2224,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.181818182,"to, the, a, from, sars-cov-2, origin"
2225,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.181818182,"evidence, that, the, as, of, a"
2226,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.181818182,"this, that, are, the, of, sars-cov-2"
2227,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.181818182,"that, the, and, be, of, to"
2228,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.181818182,"and, that, transmission, of, sars-cov-2, to, through, be"
2229,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.181818182,"the, a, at, huanan, market, and, of, with"
2230,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.181818182,"this, a, the, is, of, and"
2231,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.181818182,"animal, sars-cov-2, and, in, at, the"
2232,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.181818182,"that, the, of, cases, were, to, and, huanan"
2233,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.181818182,"that, is, not, in, any, research, to, sars-cov-2"
2234,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.181818182,"is, to, a, spillover, an, animal"
2235,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.181818182,"that, has, similarity, to, and, with"
2236,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.181818182,"to, the, high, sequence, a, coronavirus"
2237,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.181818182,"of, the, cases, were, to, huanan, and, that"
2238,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.181818182,"of, cases, in, around, the, huanan, market, with"
2239,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.181818182,"the, of, cases, in, with, around, huanan, market"
2240,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.181818182,"virus, that, is, from, an, to"
2241,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.181818182,"the, is, that, virus, to, of, and, has"
2242,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.181818182,"sars-cov-2, from, a, virus, that, is"
2243,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.181818182,"the, pangolin, is, to, be, intermediate"
2244,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.181818182,"the, is, that, virus, to, a, and, transmitted"
2245,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.181818182,"sars-cov-2, was, from, that, to, and"
2246,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.181818182,"from, with, genome, to, the, of, covid-19, virus"
2247,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Bats have been reported as being the rich source of 

coronaviruses",0.181818182,"bats, the, have, been, as, of"
2248,"with the first case being linked to  

a seafood market","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.181818182,"with, the, to, a"
2249,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.181818182,"sars-cov-2, have, been, from, to, a, identified, similarity"
2250,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.181818182,"to, have, from, a, with, sars-cov-2"
2251,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.181818182,"the, sars-cov-2, has, with, similarity, to"
2252,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.181818182,"sars-cov-2, to, a, of, and, the"
2253,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.181818182,"the, analysis, of, and, that, sars-cov-2, to, by"
2254,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.181818182,"available, that, sars-cov-2, has, a, and"
2255,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.181818182,"bat, is, to, pangolin"
2256,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.181818182,"the, between, and, bat, pangolin, is"
2257,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.181818182,"is, the, bat, to, be, of"
2258,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.181818182,"analysis, of, to, that, sars-cov-2, by, the, and"
2259,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.181818182,"has, been, that, in"
2260,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.181818182,"evidence, the, that, as, a, of"
2261,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.181818182,"the, in, similar, to, that, virus"
2262,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.181818182,"and, that, origin, the, virus, is"
2263,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.181818182,"that, similar, to, and, the, origin"
2264,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.181818182,"the, and, is, to, of, sequence"
2265,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.181818182,"the, that, to, be, and, of"
2266,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.181818182,"of, to, that, the, and, virus"
2267,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.181818182,"that, it, is, to, the, and, for, was"
2268,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.181818182,"the, sars-cov, is, to, sars-like, bat, of, genome"
2269,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.181818182,"of, virus, that, is, to, the, bat, and"
2270,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.181818182,"he, from, in, the, of, spike"
2271,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.181818182,"virus, an, is, to, that, from"
2272,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.181818182,"is, that, virus, to, a, transmitted"
2273,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.181818182,"virus, it, is, to, the, for"
2274,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.181818182,"the, are, closely, related, to, sars-cov-2"
2275,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.181818182,"bats, are, the, sars-cov-2, to, bat"
2276,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.181818182,"the, of, is, closely, related, to"
2277,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.181818182,"a, available, has, that, sars-cov-2, and"
2278,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.181818182,"sars-cov-2, is, natural, a, or, that, evidence, not"
2279,"ARS-CoV-2 is a 

natural virus, not a lab-created one.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.181818182,"is, a, natural, not"
2280,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.181818182,"through, that, to, be, sars-cov-2, and, of, transmission"
2281,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.181818182,"it, be, that, between, and, happened, an, of"
2282,"ARS-CoV-2 is a 

natural virus, not a lab-created one.",COVID-19 is a zoonotic virus,0.181818182,"is, a"
2283,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.181818182,"the, virus, covid-19, genome, of, to, with, from"
2284,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.181818182,"the, of, sars-cov-2, that, is, to"
2285,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.181818182,"the, of, similar, to, is, that"
2286,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.181818182,"the, of, identity, with, and, bat"
2287,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.181818182,"virus, the, covid-19, to, bat, and, identity, that"
2288,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.181818182,"to, in, protein, human, ace2, ("
2289,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.181818182,"sars-cov-2, is, a, virus, that, from"
2290,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.181818182,"the, hosts, of, and"
2291,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.181818182,"the, are, sars-cov-2, and"
2292,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Bats are natural hosts of many of the known  

coronaviruses",0.181818182,"the, of, coronaviruses, bats"
2293,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.181818182,"to, is, be, the, pangolin, intermediate"
2294,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.181818182,"the, virus, has, is, to, that, of, and"
2295,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.181818182,"to, is, a, virus, that, and, transmitted, the"
2296,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.181818182,"virus, that, is, transmitted, to, a"
2297,"This suggests that the BANAL series may be able to directly infect  

humans.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.181818182,"that, the, series, to, infect, humans."
2298,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.181818182,"the, of, that, is, a, virus, has, been"
2299,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.181818182,"the, genome, of, with, that, to"
2300,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.181818182,"analysis, of, virus, that, similar, to, the, was"
2301,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.181818182,"the, of, has, been, zoonotic, a"
2302,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.181818182,"that, not, sars-cov-2, to, is, any, in, research"
2303,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.181818182,"that, sars-cov-2, is, to"
2304,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.181818182,"the, of, a, zoonotic, has, been"
2305,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.181818182,"sars-cov-2, ratg13, high, to, the, of"
2306,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","bats are also important reservoir species for a great 

range of coronaviruses",0.181818182,"coronaviruses, are, a, of"
2307,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.181818182,"to, human, ace2, protein, in, ("
2308,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.181818182,"to, the, from, as, intermediate, spillover"
2309,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.181818182,"the, covid-19, to, in, seafood, market"
2310,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.181818182,"the, sars-cov-2, animal, at, in, and"
2311,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.181818182,"bats, are, and, the, reservoirs, of"
2312,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","Bats are the second  

largest order of mammals, with over 1,230 species.",0.181818182,"the, largest, of, mammals,"
2313,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.181818182,"the, bats, serve, as, of, and"
2314,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.181818182,"bats, serve, as, the, of, and"
2315,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.181818182,"the, to, discovered, in, virus, and"
2316,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.181818182,"a, from, to, have, with, sars-cov-2"
2317,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.181818182,"sars-cov-2, to, are, closely, related, the"
2318,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.181818182,"of, the, that, is, similar, to"
2319,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","This suggests that the BANAL series may be able to directly infect  

humans.",0.181818182,"the, that, to, infect, series, humans."
2320,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.181818182,"he, of, the, spike, in, from"
2321,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.181818182,"covid-19, virus, is, most, to, the"
2322,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.181818182,"with, a, and, of, at, the, huanan, market"
2323,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.181818182,"from, into, intermediate, as, and, raccoon, to, humans., this, for, the, of, that, adapted, in, a"
2324,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.181818182,"a, known, zoonotic, and, association, the, spillover, to"
2325,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.181818182,"to, natural, the, of, origin, and, evidence, is"
2326,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.181818182,"the, association, known, and, a, zoonotic, spillover, to"
2327,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.181818182,"virus, the, bat, 96.2%, sequence, identity, that, sars-cov-2"
2328,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.181818182,"evidence, that, sars-cov-2, a, natural, is, not, or"
2329,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.181818182,"that, sars-cov-2, is, of"
2330,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.181818182,"that, is, of, sars-cov-2"
2331,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.181818182,"the, genetic, of, systems, have, been, used, would"
2332,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.181818182,"the, virus, similar, to, that, in"
2333,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.181818182,"in, the, rbd, of, to, sars-cov-2, that, virus"
2334,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.181818182,"the, of, that, to, in, wuhan, china,, covid-19"
2335,"bats are also important reservoir species for a great 

range of coronaviruses","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.181818182,"are, a, of, coronaviruses"
2336,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.181818182,"the, to, market, in, is, covid-19"
2337,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.181818182,"the, covid-19, in, to, seafood, market"
2338,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.181818182,"the, analysis, that, is, of, bat"
2339,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.181818182,"it, was, that, the, and, for, to, is"
2340,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.181818182,"the, and, of, virus, is, to, that, bat"
2341,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.181818182,"virus, to, for, the, it, is"
2342,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.181818182,"the, analysis, of, that, was, to, similar, virus"
2343,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.181818182,"is, the, most, virus, to, covid-19"
2344,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.181818182,"analysis, of, the, that, is, virus"
2345,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.181818182,"for, and, to, the, of, virus"
2346,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.181818182,"these, have, a, of, in, bats, the, genus, rhinolophus, china"
2347,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.181818182,"they, were, in, the, southeast, asian"
2348,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.181818182,"the, have, in, bats, of, genus, rhinolophus, these, a, china"
2349,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.181818182,"the, in, they, were, southeast, asian"
2350,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.181818182,"in, were, contaminated, their"
2351,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.181818182,"were, contaminated, in, their"
2352,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.181818182,"this, is, a, and, of, the"
2353,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.181818182,"analysis, of, virus, that, is, the"
2354,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.181818182,"of, virus, to, the, and, for"
2355,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"ARS-CoV-2 is a 

natural virus, not a lab-created one.",0.181818182,"a, natural, is, not"
2356,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.181818182,"for, the, of, raccoon, and, intermediate, that, into, from, a, in, this, as, adapted, to, humans."
2357,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.181818182,"identical, to, sars-cov-2, genome"
2358,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.181818182,"96.2%, to, genome, was, bat, found"
2359,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.181818182,"the, virus, is, and, that, origin"
2360,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.181818182,"to, sars-cov-2, that, from, and, was"
2361,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.181818182,"sars-cov-2, coronaviruses, similarity, to, the, of"
2362,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.181818182,"be, the, natural, of, sars-, and"
2363,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.181818182,"the, and, is, of, evidence, natural, origin, to"
2364,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.181818182,"that, pangolins, hosts, for, sars-cov-2, are"
2365,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.181818182,"sars-cov-2, to, are, bat, bats, the"
2366,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.181818182,"genome, was, found, to, 96.2%, bat"
2367,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.181818182,"that, pangolins, are, hosts, for, sars-cov-2"
2368,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.181818182,"pangolin, is, to, bat"
2369,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.181818182,"is, that, sars-cov-2, of"
2370,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.181818182,"the, sars-cov-2, has, been, from, bats, of, this"
2371,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.181818182,"that, sars-cov-2, to, pangolin, cov, and, the, sars-cov-2."
2372,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.181818182,"that, sars-cov-2, the, same, origin, with, bat, cov, ratg13, guangdong"
2373,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.181818182,"the, pangolin, is, between, bat, and"
2374,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.181818182,"sars-cov-2, with, bat, cov, ratg13, guangdong, that, the, same, origin"
2375,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.181818182,"are, that, the, of, sars-cov-2, this"
2376,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.181818182,"that, sars-cov-2, are, the, origin, of"
2377,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.181818182,"studies, genome, sequences, and, on, the, origin, of"
2378,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.181818182,"the, similar, to, and, that, origin"
2379,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.181818182,"sars-cov-2., sars-cov-2, and, cov, pangolin, to, the, that"
2380,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.181818182,"that, are, the, origin, of, sars-cov-2"
2381,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.181818182,"studies, on, genome, sequences, the, origin, of, and"
2382,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.181818182,"that, has, with, and, similarity, to"
2383,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.181818182,"the, sars-cov-2, with, of, and, pangolin-cov"
2384,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.181818182,"sars-cov-2, the, of, identity, with, sars-cov"
2385,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.181818182,"the, sars-cov-2, are, and"
2386,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.181818182,"the, has, to, similarity, with, sars-cov-2"
2387,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.181818182,"the, of, sars-cov-2, with, pangolin-cov, and"
2388,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.181818182,"between, and, it, that, of, happened, an, be"
2389,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.181818182,"bat, be, the, of, and, an"
2390,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.181818182,"the, was, to, showed, identity, suggesting, that, sars-cov-2"
2391,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.181818182,"the, of, sars-cov-2, bats, transmitted, to"
2392,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.181818182,"the, in, of, rbd, to, that, sars-cov-2, virus"
2393,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.181818182,"that, is, to, sars-cov-2"
2394,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.181818182,"be, the, and, an, of, bat"
2395,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.181818182,"the, is, that, virus, a, of, has, been"
2396,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.181818182,"the, is, to, be, of, bat"
2397,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.181818182,"the, high, of, ratg13, to, sars-cov-2"
2398,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.181818182,"the, similarity, of, sars-cov-2, coronaviruses, to"
2399,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.180327869,"the, of, sars-cov-2, to, is, most, likely, a, that, strong, evidence"
2400,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.180327869,"to, the, have, in, bats, and, that, animals, a, wuhan,, china"
2401,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.180327869,"that, may, a, of, with, and, the, intermediate, hosts, for, sars-cov-2"
2402,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.180327869,"most, that, a, likely, the, of, sars-cov-2, evidence, is, strong, to"
2403,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.180327869,"have, that, the, in, bats, and, to, animals, a, wuhan,, china"
2404,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.180327869,"sars-cov-2, may, a, of, and, that, the, with, intermediate, hosts, for"
2405,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.18,"with, bat, that, the, of, sars-cov-2, and, 80%, sars-cov"
2406,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.18,"been, in, to, the, evidence, of, sars-cov-2, has, is"
2407,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.18,"is, to, the, has, been, identified, from, this, be"
2408,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.18,"could, have, been, from, an, animal, in, to, and"
2409,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.18,"the, sars-cov-2, to, it, is, also, for, and, by"
2410,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.18,"the, of, sars-cov-2, 80%, with, that, sars-cov, and, bat"
2411,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.18,"from, in, the, is, closely, related, to, of, bats"
2412,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.18,"could, have, been, from, an, animal, to, and, in"
2413,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.18,"and, that, the, novel, to, sars, mers, of, bat"
2414,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.18,"the, of, novel, that, to, bat, and, sars, mers"
2415,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.18,"the, sars-cov-2, natural, selection, on, a, that, not, manipulation."
2416,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.18,"ratg13, is, the, to, sars-cov-2,, amino, acid, in, rbd"
2417,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.18,"it, the, sars-cov-2, also, and, for, to, is, by"
2418,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.18,"other, sars-cov-2, genome, are, similar, to, and, a, the"
2419,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.18,"on, the, that, sars-cov-2, natural, selection, not, a, manipulation."
2420,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.18,"the, sars-cov-2, has, been, to, evidence, in, of, is"
2421,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.18,"the, identified, has, been, to, from, this, is, be"
2422,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.18,"the, of, in, is, closely, related, to, from, bats"
2423,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.18,"also, the, similarity, between, sars-cov-2, and, ratg13, is, viruses"
2424,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.18,"and, also, similarity, between, sars-cov-2, ratg13, is, the, viruses"
2425,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.18,"a, other, and, are, similar, to, sars-cov-2, the, genome"
2426,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.18,"the, amino, acid, in, rbd, is, to, sars-cov-2,, ratg13"
2427,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.179487179,"sars-cov, and, sars-cov-2, in, to, many, which"
2428,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.179487179,"sars-cov, and, sars-cov-2, to, in, which, many"
2429,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.179487179,"the, of, to, bat, it, is, that"
2430,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.179487179,"the, sequence, of, identity, to, sars-cov, cov"
2431,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.179487179,"the, of, identity, to, that, sars-cov-2, was"
2432,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.179487179,"sars-cov-2, the, with, of, genome,, and, to"
2433,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.179487179,"the, that, closest, virus, and, similarity, to"
2434,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.179487179,"the, for, of, sars-cov-2, humans, from, intermediate"
2435,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.179487179,"the, sars-, and, natural, may, be, mers-cov"
2436,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.179487179,"of, the, full-length, sequence, covid-19, with, identity"
2437,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.179487179,"the, is, to, identical, that, of, and"
2438,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.179487179,"of, the, genome, and, with, bat, identity"
2439,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.179487179,"the, of, and, identity, with, sars-cov-2, genome"
2440,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.179487179,"genome, identity, with, bat, that, and, sars-cov-2"
2441,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.179487179,"the, of, sars-cov-2, from, intermediate, for, humans"
2442,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.179487179,"the, of, from, market, intermediate, host, at"
2443,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.179487179,"the, of, taken, from, market, was, at"
2444,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.179487179,"of, covid-19, that, to, the, and, was"
2445,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.179487179,"and, that, the, virus, has, to, bat"
2446,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.179487179,"of, the, cases, been, in, that, which"
2447,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.179487179,"the, of, that, and, is, identical, to"
2448,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.179487179,"the, of, is, to, human, bat, be"
2449,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.179487179,"is, between, and, of, to, intermediate, be"
2450,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.179487179,"and, that, natural, origin, the, virus, likely"
2451,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.179487179,"may, be, the, natural, sars-, and, mers-cov"
2452,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.179487179,"the, is, to, be, of, bat, human"
2453,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.179487179,"the, sars-cov-2, barrier, species, is, humans, and"
2454,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.179487179,"is, to, be, of, intermediate, between, and"
2455,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.179487179,"the, of, covid-19, sequence, identity, with, full-length"
2456,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.179487179,"the, genome, of, identity, with, and, bat"
2457,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.179487179,"the, results, that, sars-cov-2, genomes, to, coronavirus"
2458,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.179487179,"the, virus, that, has, bat, and, to"
2459,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.179487179,"the, of, 80%, identity, to, and, 50%"
2460,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.179487179,"the, that, has, of, virus, and, to"
2461,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.179487179,"analysis, that, sars-cov-2, the, with, of, and"
2462,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.179487179,"the, covid-19, in, to, huanan, seafood, market"
2463,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.179487179,"the, to, sars-cov-2, was, of, et, al.,"
2464,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.179487179,"sars-cov-2, was, et, al.,, to, the, of"
2465,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.179487179,"in, yunnan, was, to, of, sars-cov-2, the"
2466,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.179487179,"the, of, from, pangolins, a, and, sars-cov-2"
2467,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.179487179,"of, the, sars-cov-2, pangolins, from, origin, and"
2468,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.179487179,"the, genome, of, sars-cov-2, identity, with, and"
2469,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.179487179,"of, that, sars-cov-2, a, with, bat, genome"
2470,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.179487179,"of, that, sars-cov-2, a, virus, has, in"
2471,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.179487179,"that, the, of, sars-, cov-2, and, is"
2472,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.179487179,"is, sars-cov-2, the, species, barrier, and, humans"
2473,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.179487179,"covid-19, to, the, huanan, seafood, market, in"
2474,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.179487179,"the, of, from, intermediate, host, at, market"
2475,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.179487179,"of, at, the, market, was, from, taken"
2476,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.179487179,"of, cases, covid-19, with, december, a, wuhan, and, the, huanan, were, approximately, earliest, known"
2477,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.179487179,"a, from, was, at, in, that, the, virus, closely, related, to, of, were, found"
2478,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.179487179,"a, of, the, covid-19, cases, were, wuhan, december, and, approximately, with, huanan, earliest, known"
2479,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.179487179,"the, shows, that, sars-cov-2, with, virus, genome,"
2480,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.179487179,"that, the, of, is, to, bat, it"
2481,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.179487179,"of, virus, that, similar, to, the, was"
2482,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.179487179,"the, of, sars-cov-2, a, from, pangolins, and"
2483,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.179487179,"the, sequence, of, to, cov, identity, sars-cov"
2484,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.179487179,"and, the, 80%, 50%, identity, to, of"
2485,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.179487179,"the, analysis, that, bats, hosts, covid-19, virus"
2486,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.179487179,"of, cases, the, in, which, that, been"
2487,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.179487179,"of, the, covid-19, to, and, that, was"
2488,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.179487179,"the, of, similar, to, that, was, virus"
2489,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.179487179,"and, that, of, the, virus, is, most"
2490,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.179487179,"that, similar, to, and, the, of, sars-cov-2."
2491,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.179487179,"the, origin, of, sars-cov-2, from, pangolins, and"
2492,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.179487179,"genome, sars-cov-2, identity, with, that, and, bat"
2493,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.179487179,"the, of, that, sars-cov-2, a, has, been"
2494,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.179487179,"the, natural, origin, likely, that, virus, and"
2495,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.179487179,"of, virus, that, is, most, the, and"
2496,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.179487179,"using, the, that, bats, hosts, for, sars-cov-2"
2497,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.179487179,"results, the, that, sars-cov-2, coronavirus, to, genomes"
2498,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.179487179,"analysis, that, the, covid-19, virus, bats, hosts"
2499,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.179487179,"in, the, of, was, a, at, found, that, virus, from, were, to, closely, related"
2500,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.179487179,"sars-cov-2, is, to, very, likely, the, bat"
2501,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.179487179,"is, the, likely, sars-cov-2, very, to, bat"
2502,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.179487179,"that, bats, the, hosts, for, sars-cov-2, using"
2503,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.179487179,"of, that, similar, to, the, and, sars-cov-2."
2504,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.179487179,"that, a, bat, genome, of, with, sars-cov-2"
2505,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.179487179,"analysis, of, the, sars-cov-2, with, that, and"
2506,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.179487179,"the, of, this, that, virus, in, for"
2507,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.179487179,"the, closest, to, that, similarity, virus, and"
2508,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.179487179,"virus, that, shows, with, the, sars-cov-2, genome,"
2509,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.179487179,"was, that, the, of, sars-cov-2, to, identity"
2510,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.179487179,"that, a, virus, in, has, of, sars-cov-2"
2511,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.179487179,"of, sars-cov-2, has, been, that, the, a"
2512,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.179487179,"this, that, in, the, virus, for, of"
2513,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.179487179,"the, to, sars-cov-2, was, in, of, yunnan"
2514,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.179487179,"the, amino, acid, of, is, to, than"
2515,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.179487179,"is, the, to, amino, acid, of, than"
2516,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.179104478,"suggests, that, of, sars-, cov-2, from, to, humans, a, in, sars-cov-2, the"
2517,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.179104478,"sars-cov, and, to, the, beta, bats, could, be, of, with, or, as"
2518,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.179104478,"bats, as, the, to, be, sars-cov, or, with, of, beta, could, and"
2519,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.179104478,"to, sars-cov-2, a, of, in, the, and, it, has, been, that, with"
2520,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.179104478,"from, in, humans, sars-, cov-2, the, of, suggests, that, a, sars-cov-2, to"
2521,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.179104478,"in, the, of, it, to, that, sars-cov-2, has, been, with, and, a"
2522,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.178807947,"at, an, infected, to, a, palm, however,, as, civets, sampled, from, animal, farms, in, tested, for, the, by, contrast,, collected, markets, sars, live, were, one, of, and"
2523,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.178807947,"as, a, of, the, palm, civets, at, animal, farms, and, live, markets, were, by, in, an, to, sars, however,, infected, for, one, from, tested, contrast,, collected, sampled"
2524,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.178571429,"the, rhinolophid, bats, are, in"
2525,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.178571429,"the, are, in, rhinolophid, bats"
2526,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.178571429,"the, natural, of, a, and"
2527,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.178571429,"the, of, a, variety, and"
2528,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.178571429,"the, sars-cov-2, genome, to, bat"
2529,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.178571429,"the, of, as, malayan, pangolins"
2530,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.178571429,"the, is, to, and, animal"
2531,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.178571429,"the, a, spillover, an, to"
2532,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.178571429,"of, natural, reservoirs, and, the"
2533,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.178571429,"bats, are, the, of, and"
2534,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.178571429,"the, a, zoonotic, from, to"
2535,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.178571429,"the, outbreak, in, 2003,, from"
2536,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.178571429,"analysis, that, the, is, sars-cov-2"
2537,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.178571429,"sars-cov-2, that, identical, to, and"
2538,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.178571429,"the, to, identical, sars-cov-2, and"
2539,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.178571429,"the, animal, to, be, of"
2540,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.178571429,"animal, to, sars-cov-2, and, the"
2541,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.178571429,"the, of, sars-cov-2, and, to"
2542,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.178571429,"the, a, zoonotic, and, in"
2543,"expended to make the simple point 

that COVID-19 had a natural origin.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.178571429,"to, the, that, a, natural"
2544,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.178571429,"other, with, sars-cov-2, from, zoonotic"
2545,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.178571429,"with, other, sars-cov-2, from, zoonotic"
2546,"expended to make the simple point 

that COVID-19 had a natural origin.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.178571429,"to, the, that, covid-19, a"
2547,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.178571429,"the, animal, of, be, to"
2548,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.178571429,"the, sars-cov-2, a, from, malayan"
2549,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.178571429,"is, to, animal, and, the"
2550,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.178571429,"that, animal, origin, and, is"
2551,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.178571429,"the, and, with, bat, sars-cov,"
2552,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.178571429,"the, of, has, been, bat"
2553,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.178571429,"from, to, humans, is, the"
2554,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.178571429,"from, bats, to, is, the"
2555,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.178571429,"is, and, that, origin, animal"
2556,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.178571429,"from, humans, is, and, the"
2557,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.178571429,"initially, that, the, is, sars-cov-2"
2558,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.178571429,"the, virus, from, to, with"
2559,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.178571429,"the, of, coronaviruses, beta, sars-cov-2"
2560,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.178571429,"is, that, sars-cov-2, of, coronavirus"
2561,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.178571429,"with, sars-cov,, bat, and, the"
2562,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.178571429,"is, that, sars-cov-2, a, bat"
2563,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.178571429,"that, genome, sequences, are, similar, to, and, a, the, of"
2564,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.178571429,"ratg13, the, bat, to, sars-cov-2,, sequence, in, of, s, gene"
2565,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.178571429,"is, the, most, likely, to"
2566,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.178571429,"and, pangolin, coronaviruses, to, sars-cov-2."
2567,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.178571429,"in, malayanus, yunnan, was, the"
2568,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.178571429,"be, the, of, an, animal"
2569,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.178571429,"the, of, malayan, pangolins, as"
2570,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.178571429,"a, from, the, malayan, sars-cov-2"
2571,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.178571429,"the, of, a, between, and"
2572,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.178571429,"the, and, a, zoonotic, in"
2573,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.178571429,"has, been, the, of, bat"
2574,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.178571429,"in, the, of, a, and"
2575,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.178571429,"a, has, genome, similarity, sars-cov-2"
2576,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.178571429,"in, an, from, species, of, bats, to, sars-cov-2, the, humans"
2577,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.178571429,"sars-cov-2, has, a, similarity, genome"
2578,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.178571429,"from, with, to, the, virus"
2579,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.178571429,"of, from, bats, to, humans, an, in, sars-cov-2, species, the"
2580,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.178571429,"the, residues, in, sars-cov-2, pangolin-cov"
2581,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.178571429,"to, a, spillover, an, the"
2582,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.178571429,"to, the, a, from, zoonotic"
2583,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.178571429,"the, animal, sars-cov-2, and, to"
2584,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.178571429,"the, and, to, were, in"
2585,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.178571429,"of, the, sars-cov-2, beta, coronaviruses"
2586,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.178571429,"bats, of, and, the, animal"
2587,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.178571429,"to, were, and, in, the"
2588,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.178571429,"for, and, to, the, virus"
2589,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","expended to make the simple point 

that COVID-19 had a natural origin.",0.178571429,"the, covid-19, to, that, a"
2590,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.178571429,"and, the, natural, reservoirs, of"
2591,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.178571429,"of, that, sars-cov-2, coronavirus, is"
2592,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.178571429,"from, to, humans, the, is"
2593,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.178571429,"the, is, to, from, bats"
2594,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.178571429,"is, the, and, humans, from"
2595,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.178571429,"the, of, a, and, in"
2596,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.178571429,"between, and, in, the, of"
2597,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.178571429,"this, indicates, that, the, of"
2598,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.178571429,"the, virus, for, and, to"
2599,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.178571429,"the, sars-cov-2, to, bat, genome"
2600,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.178571429,"sars-cov-2, that, and, identical, to"
2601,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.178571429,"sars-cov-2, a, that, is, bat"
2602,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.178571429,"the, is, to, most, likely"
2603,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.178571429,"that, the, bats, hosts, for, are, more, probable, sars-cov-2, than"
2604,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.178571429,"the, sars-cov-2, that, bats, are, more, probable, hosts, for, than"
2605,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.178571429,"the, genome, of, and, that, sequences, a, are, similar, to"
2606,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.178571429,"bat-sl-cov-2, and, pangolin-cov, that, sars-cov-2"
2607,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.178571429,"and, pangolin-cov, the, of, sars-cov-2"
2608,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.178571429,"in, the, of, between, and"
2609,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.178571429,"that, sars-cov-2, bat-sl-cov-2, and, pangolin-cov"
2610,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.178571429,"the, of, sars-cov-2, pangolin-cov, and"
2611,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.178571429,"the, sars-cov-2, and, identical, to"
2612,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.178571429,"the, pangolin-cov, residues, sars-cov-2, in"
2613,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.178571429,"the, an, animal, be, of"
2614,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.178571429,"was, in, yunnan, the, malayanus"
2615,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.178571429,"the, of, bat, s, gene, sequence, in, ratg13, to, sars-cov-2,"
2616,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.178571429,"pangolin, and, coronaviruses, to, sars-cov-2."
2617,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.178571429,"the, analysis, that, sars-cov-2, is"
2618,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.178571429,"is, that, sars-cov-2, the, initially"
2619,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.178082192,"that, may, have, been, by, a, of, to, and, the, intermediate, for, sars-cov-2"
2620,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.178082192,"intermediate, and, to, for, by, the, of, that, sars-cov-2, may, have, been, a"
2621,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.177777778,"found, the, of, sequence, that, sars-cov-2, was, to"
2622,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.177777778,"ratg13,, a, is, identical, to, the, that, it"
2623,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.177777778,"that, the, sars-cov-2, and, bat, cov, ratg13, same"
2624,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.177777778,"the, covid-19, market, is, of, zoonotic, origin, to"
2625,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.177777778,"and, a, of, sars-cov-2, is, an, the, to"
2626,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.177777778,"this, to, the, of, evidence, is, yet, be"
2627,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.177777778,"studies, the, bat, coronavirus, and, that, was, not"
2628,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.177777778,"that, the, a, market, in, wuhan,, to, and"
2629,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.177777778,"of, the, coronavirus, has, and, identity, with, bat"
2630,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.177777778,"a, coronavirus, the, with, genome, that, to, of"
2631,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.177777778,"the, that, sars-cov-2, of, virus, and, similarity, to"
2632,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.177777778,"the, has, of, identity, with, coronavirus, and, bat"
2633,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.177777778,"that, the, in, wuhan,, to, a, and, market"
2634,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.177777778,"may, of, to, pangolins, are, the, intermediate, hosts"
2635,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.177777778,"the, a, genome, of, to, with, that, coronavirus"
2636,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.177777778,"was, found, that, the, sequence, of, sars-cov-2, to"
2637,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.177777778,"(2020), of, sars-cov-2, ratg13, in, region, the, to"
2638,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.177777778,"the, of, to, market, is, zoonotic, origin, covid-19"
2639,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.177777778,"found, sars-cov-2, from, smuggled, pangolins, including, and, coronaviruses"
2640,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.177777778,"that, the, is, identical, to, a, ratg13,, it"
2641,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.177777778,"to, this, that, sars-cov-2, the, virus, of, we"
2642,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.177777778,"studies, and, that, not, the, bat, coronavirus, was"
2643,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.177777778,"to, and, of, it, is, that, similar, bat"
2644,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.177777778,"the, to, evidence, of, this, is, yet, be"
2645,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.177777778,"sars-cov-2, is, to, a, of, an, and, the"
2646,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.177777778,"(2020), the, of, ratg13, to, sars-cov-2, in, region"
2647,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.177777778,"are, to, the, hosts, of, pangolins, may, intermediate"
2648,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.177777778,"the, bat, cov, ratg13, and, that, sars-cov-2, same"
2649,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.177777778,"also, found, that, the, of, pangolin, to, sars-cov-2."
2650,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.177777778,"the, similarity, sars-cov-2, and, of, virus, to, that"
2651,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.177777778,"that, sars-cov-2, the, at, of, virus, to, pangolin-cov"
2652,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.177777778,"to, the, of, rbd, pangolin-cov, virus, bind, hace2."
2653,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.177777778,"the, of, to, that, sars-cov-2, we, this, virus"
2654,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.177777778,"the, rbd, of, pangolin-cov, to, virus, bind, hace2."
2655,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.177777778,"of, that, it, is, similar, to, bat, and"
2656,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.177777778,"coronaviruses, sars-cov-2, found, including, and, pangolins, smuggled, from"
2657,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.177777778,"found, that, also, to, pangolin, the, of, sars-cov-2."
2658,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.177419355,"in, the, was, a, that, virus, to, human, and, variant, sequence"
2659,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.177419355,"of, cases, with, a, to, and, the, huanan, market, were, in"
2660,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.177419355,"a, novel, the, coronavirus, bats, could, be, reservoirs, of, with, host,"
2661,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.177419355,"a, of, be, the, host,, novel, coronavirus, with, bats, could, reservoirs"
2662,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.177419355,"variant, a, the, to, that, in, sequence, human, virus, and, was"
2663,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.177419355,"the, of, cases, were, in, to, with, a, and, huanan, market"
2664,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.177419355,"sars-cov-2, is, in, the, same, with, bat, cov, ratg13, guangdong, pangolin"
2665,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.177419355,"the, that, sars-cov-2, are, cluster, with, bat, cov, ratg13, than, pangolin"
2666,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.177419355,"in, sars-cov-2, with, bat, cov, ratg13, guangdong, pangolin, the, same, is"
2667,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.177419355,"are, sars-cov-2, with, bat, cov, ratg13, pangolin, cluster, that, the, than"
2668,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.176470588,"bats, are, the, reservoir, of, and"
2669,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.176470588,"the, are, of, bats, in, china"
2670,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.176470588,"of, the, that, sars-cov-2, is, a"
2671,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.176470588,"of, the, sequence, sars-cov-2, is, to"
2672,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.176470588,"in, the, with, genome, to, of"
2673,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.176470588,"bat, and, to, in, the, of"
2674,"Bats are the second  

largest order of mammals, with over 1,230 species.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.176470588,"bats, are, the, second, order, of"
2675,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.176470588,"transmission, of, to, an, is, a, coronavirus, sars-cov-2, the"
2676,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.176470588,"bats, are, the, reservoirs, of, and"
2677,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",Bats are likely reservoir hosts for SARS-CoV-2,0.176470588,"sars-cov-2, are, hosts"
2678,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.176470588,"from, to, is, a, coronavirus, homology, with, sars-cov-2, the"
2679,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.176470588,"that, the, of, sars-cov-2, is, bat"
2680,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.176470588,"that, shows, the, sars-cov-2, in, bat"
2681,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.176470588,"that, bat, genome, of, with, sars-cov-2"
2682,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.176470588,"of, the, that, and, sars-cov-2, is"
2683,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.176470588,"is, that, the, sars-cov-2, to, bat"
2684,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.176470588,"of, bats, to, sars-cov-2, and, the"
2685,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.176470588,"sars-cov-2, are, to, and, the, of"
2686,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.176470588,"and, the, which, that, by, a"
2687,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.176470588,"that, the, of, are, from, bat"
2688,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.176470588,"a, in, the, with, of, at"
2689,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.176470588,"at, the, virus, was, of, a"
2690,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.176470588,"all, that, the, a, weapons, program"
2691,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.176470588,"is, sars-cov-2, or, a, progenitor, in"
2692,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.176470588,"evidence, that, sars-cov-2, is, a, in"
2693,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.176470588,"as, to, the, of, be, possible"
2694,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.176470588,"to, is, the, virus, originated, bats, and, was, transmitted"
2695,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.176470588,"that, a, pangolin, virus, to, and, the, intermediate, sars-cov-2"
2696,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.176470588,"the, of, that, to, a, with, bat, genome, pangolin"
2697,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.176470588,"of, the, analysis, that, sars-cov-2, to"
2698,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.176470588,"is, to, bat, be, the, possible"
2699,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.176470588,"the, to, of, intermediate, bat, and"
2700,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.176470588,"the, and, to, intermediate, hosts, of"
2701,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.176470588,"that, the, zoonotic, may, of, to"
2702,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.176470588,"to, is, virus, originated, bats, and, was, transmitted, the"
2703,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.176470588,"of, a, virus, at, the, was"
2704,"All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.176470588,"all, the, that, a, weapons, program"
2705,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.176470588,"of, virus, that, is, the, was"
2706,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.176470588,"that, the, virus, in, and, to"
2707,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.176470588,"may, the, of, to, that, zoonotic"
2708,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.176470588,"the, is, to, be, possible, bat"
2709,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.176470588,"the, that, is, related, to, sars-cov-2"
2710,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.176470588,"the, first, seafood, market, in, wuhan"
2711,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.176470588,"the, has, 80%, to, of, bat"
2712,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.176470588,"analysis, of, the, sars-cov-2, with, that, sars-cov, and, novel"
2713,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.176470588,"are, bat, that, the, of, from"
2714,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.176470588,"the, coronaviruses, to, closely, related, in"
2715,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.176470588,"the, related, to, from, is, also"
2716,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.176470588,"of, virus, that, to, the, and"
2717,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.176470588,"genome, from, patients, in, the, of, virus, between, and"
2718,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.176470588,"the, sars-cov-2, is, to, of, sequence"
2719,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.176470588,"analysis, of, to, that, sars-cov-2, the"
2720,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.176470588,"the, of, has, 80%, to, bat"
2721,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.176470588,"novel, with, that, the, of, sars-cov-2, and, analysis, sars-cov"
2722,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.176470588,"revealed, that, the, of, sars-cov-2, and, sars-cov, two, a"
2723,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.176470588,"a, the, with, genome, that, of"
2724,Bats are likely reservoir hosts for SARS-CoV-2,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.176470588,"are, hosts, sars-cov-2"
2725,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.176470588,"that, sars-cov-2, and, which, as, a, (zhou, p, et, al.,, n, 2020)"
2726,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.176470588,"a, of, the, sars-cov-2, that, sars-cov, revealed, and, two"
2727,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.176470588,"sars-cov-2, a, and, as, n, et, al.,, 2020), (zhou, p, which, that"
2728,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.176470588,"with, the, to, in, of, genome"
2729,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.176470588,"with, a, of, at, the, in"
2730,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.176470588,"a, of, the, genome, with, that"
2731,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.176470588,"that, the, of, sars-cov-2, is, a"
2732,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.176470588,"the, of, has, been, in, for"
2733,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.176470588,"the, possible, to, be, of, as"
2734,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.176470588,"that, sars-cov-2, is, related, to, the"
2735,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.176470588,"that, the, of, sars-cov-2, and, this, has, more, been"
2736,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.176470588,"that, sars-cov-2, has, the, with, of, virus, and, to"
2737,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.176470588,"sars-cov-2, is, to, a, of, an, coronavirus, the, transmission"
2738,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.176470588,"to, the, homology, with, a, coronavirus, from, sars-cov-2, is"
2739,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.176470588,"genome, of, sars-cov-2, with, that, bat"
2740,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.176470588,"the, of, sars-cov-2, that, and, is"
2741,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.176470588,"from, bats, to, humans, and, the"
2742,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.176470588,"s, protein, sequence, homology, with, of"
2743,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.176470588,"s, protein, sequence, of, homology, with"
2744,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.176470588,"the, of, sars-cov-2, to, is, result, natural, a, or"
2745,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.176470588,"the, bats, are, in, of, china"
2746,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Bats are the second  

largest order of mammals, with over 1,230 species.",0.176470588,"bats, are, the, second, of, order"
2747,"Bats have been reported as being the rich source of 

coronaviruses",Coronaviruses account for over 30% of the world’s viruses.,0.176470588,"the, of, coronaviruses"
2748,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.176470588,"the, in, closely, related, to, coronaviruses"
2749,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.176470588,"the, and, to, bat, in, of"
2750,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.176470588,"in, the, and, an, of, bat"
2751,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.176470588,"the, of, that, and, is, to"
2752,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.176470588,"is, that, are, the, similar, to"
2753,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.176470588,"rbd, of, shown, to, ace2, the"
2754,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.176470588,"the, related, to, covid-19, is, most"
2755,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.176470588,"the, shows, that, sars-cov-2, in, bat"
2756,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.176470588,"the, is, result, of, natural, sars-cov-2, or, to, a"
2757,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.176470588,"this, to, that, natural, the, most, of, evidence, is"
2758,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.176470588,"the, and, by, which, a, that"
2759,"t some virus detected in pangolins 

were capable of infecting humans.","In the 

case of MERS, dromedaries were the principal host.",0.176470588,"in, were, of"
2760,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.176470588,"the, to, of, intermediate, hosts, and"
2761,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.176470588,"the, virus, to, and, that, in"
2762,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.176470588,"in, transmitted, to, humans, through, intermediate"
2763,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.176470588,"is, that, the, virus, was, of"
2764,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.176470588,"that, the, covid-19, is, of, and"
2765,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.176470588,"seafood, market, in, wuhan, the, first"
2766,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.176470588,"from, bats, to, and, the, humans"
2767,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.176470588,"isolated, from, pangolins, in, guangdong, is, sars-cov-2, the, of"
2768,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.176470588,"of, the, sars-cov-2, isolated, in, pangolins, from, is, guangdong"
2769,"In the 

case of MERS, dromedaries were the principal host.","t some virus detected in pangolins 

were capable of infecting humans.",0.176470588,"in, of, were"
2770,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.176470588,"of, covid-19, that, is, the, and"
2771,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.176470588,"the, is, also, related, to, from"
2772,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.176470588,"is, the, most, related, to, covid-19"
2773,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.176470588,"that, the, most, likely, hosts, as, to, a, bat"
2774,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.176470588,"the, sars-cov-2, was"
2775,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.176470588,"sars-cov-2, of, the"
2776,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.176470588,"that, sars-cov-2, has, been, in, animal"
2777,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.176470588,"shown, the, rbd, of, to, ace2"
2778,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.176470588,"in, was, to, of, sars-cov-2, the"
2779,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.176470588,"the, of, to, is, most, natural, that, this, evidence"
2780,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.176470588,"the, sars-cov-2, that, is, to, bat"
2781,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.176470588,"the, are, similar, to, is, that"
2782,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.176470588,"the, as, a, that, most, likely, to, bat, hosts"
2783,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.176470588,"to, sars-cov-2, a, virus, that, and, the, pangolin, intermediate"
2784,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.176470588,"the, of, that, sars-cov-2, are, to, a, with, pangolin"
2785,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.176470588,"bat, cov, ratg13, is, sars-cov-2, than"
2786,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.176470588,"the, of, more, that, sars-cov-2, has, been, and, this"
2787,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.176470588,"sars-cov-2, is, very, likely, to, originated"
2788,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.176470588,"genome, of, the, virus, from, patients, in, between, and"
2789,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.176470588,"the, of, sars-cov-2, are, and, to"
2790,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.176470588,"the, a, genome, of, to, with, that, pangolin, bat"
2791,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.176470588,"that, a, of, pangolin, with, to, are, the, sars-cov-2"
2792,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.176470588,"the, sars-cov-2, with, of, and, to"
2793,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.176470588,"bats, of, and, are, the, reservoir"
2794,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.176470588,"the, of, sars-cov-2, with, and, to"
2795,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.176470588,"bat, and, an, in, the, of"
2796,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.176470588,"sars-cov-2, is, to, very, likely, originated"
2797,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.176470588,"is, evidence, that, sars-cov-2, a, in"
2798,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.176470588,"the, of, in, has, been, for"
2799,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.176470588,"has, been, that, sars-cov-2, in, animal"
2800,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.176470588,"of, sars-cov-2, was, to, the, in"
2801,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.176,"the, conditions, animals, are, in, wet, markets, a, of, “the, large, viruses, on, that, bats, infected, were, animal, and, palm, market, supply"
2802,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.176,"that, palm, were, infected, bats, in, the, wet, market, supply, a, animals, and, conditions, large, of, “the, animal, markets, are, on, viruses"
2803,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.176,"early, cases, with, the, huanan, and, for, of, all, a, significant, to, prc, officials, who-china, that, were, covid-19, in, is, by, market"
2804,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.176,"the, huanan, market, is, that, prc, officials, significant, in, for, who-china, of, cases, were, to, by, and, with, a, all, early, covid-19"
2805,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.175675676,"and, it, to, this, not, for, the, of, that, sars-cov-2, been, in, a"
2806,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.175675676,"in, the, of, for, it, not, to, that, sars-cov-2, been, and, this, a"
2807,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.175438596,"sars-cov-2, is, a, and, from, be, as, to, that, bats"
2808,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.175438596,"to, sars-cov-2, is, be, a, that, from, bats, and, as"
2809,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.175438596,"analysis, suggests, that, the, in, bats, to, humans, intermediate, of"
2810,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.175438596,"suggests, that, of, bats, to, humans, intermediate, in, analysis, the"
2811,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.175438596,"between, bats, and, pangolins, have, the, in, wildlife, markets, china"
2812,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.175438596,"bats, the, and, have, in, china, between, pangolins, wildlife, markets"
2813,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.175438596,"are, 2, to, sars-cov-, the, and, that, pangolins, hosts, for"
2814,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.175438596,"that, sars-cov-, 2, to, and, pangolins, are, the, hosts, for"
2815,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.175,"and, many, genetic, are, very, to, sars-cov"
2816,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.175,"sars-cov-2, genetic, many, other, sarbecoviruses,, and, a"
2817,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.175,"sars-cov-2, and, bat, pangolin, coronaviruses, very, to"
2818,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.175,"bats, are, the, numerous, known, of, and"
2819,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.175,"sars-cov, and, are, to, genetic, many, very"
2820,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.175,"and, sars-cov-2, a, genetic, sarbecoviruses,, many, other"
2821,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.175,"a, to, bat, that, the, of, sars-cov-2"
2822,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.175,"it, is, that, a, of, sars-cov-2, the"
2823,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.175,"the, of, to, that, sars-cov-2, was, t"
2824,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.175,"that, the, virus, and, sequence, identity, to"
2825,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.175,"that, sars-cov-2, the, same, bat, cov, ratg13"
2826,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.175,"the, of, and, in, with, sars-cov-2, genome"
2827,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.175,"sars-cov-2, is, to, in, the, with, bat"
2828,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.175,"the, of, sars-cov-2, to, with, bat, genome"
2829,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.175,"bats, of, numerous, and, are, known, the"
2830,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.175,"and, human, that, a, the, virus, is"
2831,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.175,"the, of, to, bats, as, hosts, for"
2832,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.175,"were, in, wuhan,, to, a, and, market"
2833,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.175,"the, virus, to, mers-cov, and, sars-cov, that"
2834,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.175,"through, the, in, humans, from, animals, china"
2835,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.175,"bat, to, is, sars-cov-2, the, whole, genome"
2836,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.175,"the, of, and, sars-cov-2, animal, transmitted, to"
2837,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.175,"to, that, natural, the, of, origin, evidence"
2838,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.175,"studies, that, sars-cov-2, genome, are, and, the"
2839,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.175,"studies, the, bat, coronavirus, and, that, was"
2840,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.175,"that, the, of, sars-cov-2, to, a, bat"
2841,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.175,"the, known, and, huanan, market, of, to"
2842,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.175,"the, that, in, a, to, two, market"
2843,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.175,"the, earliest, cases, huanan, market, a, to"
2844,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.175,"the, show, that, are, more, to, a"
2845,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.175,"the, of, at, this, is, a, in"
2846,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.175,"et, al., a, of, by, at, the"
2847,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.175,"in, a, that, the, two, to, market"
2848,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.175,"that, evidence, in, from, a, spillover, to"
2849,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.175,"evidence, that, in, a, to, spillover, from"
2850,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.175,"a, that, the, virus, to, bat, and"
2851,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.175,"studies, and, that, the, bat, coronavirus, was"
2852,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.175,"genome, 96.2%, sequence, bat, that, and, a"
2853,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.175,"were, to, a, and, market, in, wuhan,"
2854,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.175,"a, in, the, with, that, to, of"
2855,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.175,"the, virus, has, to, that, of, and"
2856,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.175,"the, of, that, sars-cov-2, a, virus, has"
2857,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.175,"the, animal, of, sars-cov-2, and, transmitted, to"
2858,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.175,"the, virus, in, bats, and, transmitted, to"
2859,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.175,"the, in, humans, through, from, animals, china"
2860,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.175,"the, virus, which, covid-19, has, in, bats"
2861,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.175,"that, the, virus, in, and, to, humans"
2862,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.175,"that, virus, to, sars-cov, and, mers-cov, the"
2863,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.175,"virus, the, to, and, sequence, identity, that"
2864,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.175,"the, of, to, may, be, is, and"
2865,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.175,"to, that, the, virus, bats, be, of"
2866,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.175,"analysis, revealed, that, is, to, the, bat"
2867,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.175,"the, sars-cov-2, of, genome, identical, to, bat"
2868,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.175,"the, of, sars-cov-2, is, identical, and, to"
2869,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.175,"in, the, covid-19, virus, which, has, bats"
2870,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.175,"to, humans, is, contact, between, and, be"
2871,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.175,"the, of, two, and, with, sars-cov-2, genome"
2872,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.175,"the, of, that, sars-cov-2, a, with, genome"
2873,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.175,"that, the, of, in, to, with, a"
2874,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.175,"a, horseshoe, bat, in, yunnan, of, sars-cov-2"
2875,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.175,"the, closely, related, virus, to, sars-cov-2, in"
2876,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.175,"analysis, of, the, hypothesis, that, sars-cov-2, virus"
2877,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.175,"the, of, intermediate, host, species, that, from, a, found, in, suggests, humans, with, to"
2878,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.175,"with, the, and, sars-cov-2, in, of, genome"
2879,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.175,"of, the, sars-cov-2, genome, with, and, two"
2880,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.175,"sars-cov-2, in, of, a, horseshoe, bat, yunnan"
2881,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.175,"ratg13, the, to, amino, acid, in, s"
2882,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.175,"is, the, and, may, be, of, to"
2883,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.175,"the, whole, genome, sars-cov-2, is, to, bat"
2884,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.175,"is, the, sars-cov-2, as, similar, to, bat"
2885,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.175,"the, partial, furin, cleavage, site, banal-116, and"
2886,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.175,"banal-116, and, partial, furin, cleavage, site, the"
2887,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.175,"in, the, sars-cov-2, closely, related, to, virus"
2888,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.175,"suggests, that, of, from, to, humans, intermediate, host, a, found, in, with, species, the"
2889,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.175,"the, huanan, market, known, to, and, of"
2890,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.175,"a, the, earliest, cases, to, huanan, market"
2891,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.175,"to, the, of, bats, as, hosts, for"
2892,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.175,"that, the, of, sars-cov-2, is, a, it"
2893,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.175,"t, was, that, the, of, sars-cov-2, to"
2894,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.175,"and, the, virus, transmitted, bats, to, in"
2895,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.175,"the, to, that, virus, in, and, humans"
2896,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.175,"analysis, revealed, that, is, to, bat, the"
2897,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.175,"is, contact, between, humans, and, to, be"
2898,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.175,"genome, bat, and, that, sequence, 96.2%, a"
2899,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.175,"hypothesis, the, analysis, of, that, sars-cov-2, virus"
2900,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.175,"a, is, the, that, human, virus, and"
2901,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.175,"evidence, to, the, that, of, natural, origin"
2902,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.175,"the, that, are, more, likely, genome, than"
2903,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.175,"bat, to, as, is, similar, sars-cov-2, the"
2904,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.175,"the, virus, a, that, bat, and, to"
2905,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.175,"the, phylogenetic, that, of, virus, and, to"
2906,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.175,"of, a, at, the, by, et, al."
2907,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.175,"with, the, sars-cov-2, is, to, bat, in"
2908,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.175,"sars-cov-2, bat, ratg13, pangolin, very, to, the"
2909,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.175,"the, bat, cov, ratg13, that, sars-cov-2, same"
2910,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.175,"studies, that, sars-cov-2, and, are, the, genome"
2911,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.175,"with, the, sars-cov-2, to, bat, of, genome"
2912,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.175,"a, show, that, the, are, more, to"
2913,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.175,"a, of, the, sars-cov-2, genome, with, that"
2914,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.175,"the, genome, that, are, more, likely, than"
2915,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.175,"sars-cov-2, bat, ratg13, pangolin, to, the, of"
2916,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.175,"the, sars-cov-2, and, of, is, identical, to"
2917,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.175,"of, phylogenetic, that, the, virus, to, and"
2918,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.175,"that, the, virus, bats, be, of, to"
2919,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.175,"this, is, a, of, at, the, in"
2920,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.175,"a, of, has, that, sars-cov-2, the, virus"
2921,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.175,"to, amino, acid, in, ratg13, the, s"
2922,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.175,"and, sars-cov-2, to, bat, pangolin, coronaviruses, very"
2923,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.175,"sars-cov-2, to, very, the, bat, ratg13, pangolin"
2924,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.175,"the, of, sars-cov-2, to, bat, ratg13, pangolin"
2925,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.174603175,"analysis, of, covid-19, virus, that, is, to, the, for, was, sars-cov-2."
2926,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.174603175,"of, to, the, virus, that, covid-19, was, analysis, is, for, sars-cov-2."
2927,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.174418605,"lineage, b, and, at, the, that, zoonotic, of, sars-cov-2, into, in, this, from, a, by"
2928,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.174418605,"a, of, the, from, lineage, this, by, that, sars-cov-2, and, at, zoonotic, in, b, into"
2929,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.173913043,"of, coronaviruses, bat, reservoir"
2930,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.173913043,"and, coronaviruses, to, sars-cov-2."
2931,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.173913043,"sars-cov-2, virus, is, in"
2932,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.173913043,"to, identical, in, sars-cov-2"
2933,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.173913043,"and, also, a, of, in, their, receptor, is, an, the, for, to"
2934,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.173913043,"the, may, be, of"
2935,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.173913043,"bats, the, of, and"
2936,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.173913043,"sars-cov-2, in, the, shows, that, protein, is, of"
2937,"bats are also important reservoir species for a great 

range of coronaviruses","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.173913043,"bats, are, for, of"
2938,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.173913043,"a, from, animals, to, humans, for, the, time"
2939,"According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.173913043,"to, the, sars-cov-2, of"
2940,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","with the first case being linked to  

a seafood market",0.173913043,"a, to, the, first"
2941,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.173913043,"that, sars-cov-2, in, or"
2942,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.173913043,"in, the, first, live, of, from, found, that, tested, positive, for, as, raccoon, market, virus, was, to, were, a, is"
2943,"Bats are the second  

largest order of mammals, with over 1,230 species.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.173913043,"bats, the, of, with"
2944,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.173913043,"the, cases, and, huanan, market, of, a, to"
2945,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.173913043,"the, of, is, identical, to, that, which, virus"
2946,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.173913043,"is, sars-cov-2, and, pangolin, to, the, that, originated"
2947,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Bats have been reported as being the rich source of 

coronaviruses",0.173913043,"been, the, of, coronaviruses"
2948,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.173913043,"shown, to, sars-cov-2, pangolin"
2949,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.173913043,"the, to, be, bat"
2950,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.173913043,"the, of, to, suggesting, that, sars-cov-2, was, transmitted"
2951,"expended to make the simple point 

that COVID-19 had a natural origin.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.173913043,"to, the, that, had"
2952,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.173913043,"the, is, to, in"
2953,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.173913043,"previous, studies, the, reservoir, for, sars-cov, and, mers-cov"
2954,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.173913043,"the, of, are, reservoir"
2955,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.173913043,"of, the, natural, reservoir"
2956,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.173913043,"the, of, sars-cov-2, to"
2957,"An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.173913043,"reservoir, of, coronaviruses, bat"
2958,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.173913043,"are, the, reservoir, of"
2959,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.173913043,"that, the, similarity, between, sars-cov-2, and, bat, is"
2960,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.173913043,"that, sars-cov-2, may, have"
2961,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.173913043,"that, is, to, from"
2962,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.173913043,"the, a, from, animals, to, humans, time, for"
2963,"with the first case being linked to  

a seafood market","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.173913043,"the, first, to, a"
2964,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.173913043,"are, closely, related, coronaviruses, to, sars-cov-2, the, bat"
2965,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.173913043,"the, are, in, and"
2966,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.173913043,"a, from, the, china, has, sequence, with, sars-cov-2"
2967,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.173913043,"in, yunnan, province,, has, the, with, identity, genome"
2968,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.173913043,"virus, is, sars-cov-2, in"
2969,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.173913043,"is, that, sars-cov-2, a"
2970,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.173913043,"that, sars-cov-2, is, from"
2971,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.173913043,"the, animal, of, and"
2972,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Bats are natural hosts of many of the known  

coronaviruses",0.173913043,"the, of, coronaviruses, natural"
2973,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.173913043,"is, likely, to, be"
2974,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.173913043,"has, a, sequence, sars-cov-2, with, the, from, china"
2975,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.173913043,"coronaviruses, to, and, sars-cov-2."
2976,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.173913043,"may, be, the, of"
2977,"This suggests that the BANAL series may be able to directly infect  

humans.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.173913043,"that, the, may, be"
2978,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.173913043,"sars-cov-2, a, between, and"
2979,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.173913043,"the, sarbecovirus, of, and, pangolins, as, origin, sars-cov-2"
2980,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.173913043,"ratg13, the, to, its, sequence, in, rbd, of"
2981,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.173913043,"coronavirus, with, similarity, sars-cov-2"
2982,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.173913043,"is, origin, the, fact, that, has, been, by"
2983,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","bats are also important reservoir species for a great 

range of coronaviruses",0.173913043,"of, bats, are, for"
2984,"a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.173913043,"coronavirus, similarity, with, sars-cov-2"
2985,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.173913043,"sars-cov-2, found, to, bat"
2986,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.173913043,"sars-cov-2, is, a, natural, virus, to, the, pandemic"
2987,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Bats are the second  

largest order of mammals, with over 1,230 species.",0.173913043,"of, the, bats, are"
2988,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","Bats are the second  

largest order of mammals, with over 1,230 species.",0.173913043,"the, of, with, bats"
2989,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.173913043,"the, of, animal, and"
2990,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.173913043,"to, and, that, related, in, bat, including, southeast"
2991,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.173913043,"sars-cov-2, to, are, closely, related, coronaviruses, bat, the"
2992,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.173913043,"in, a, of, to, the, virus, that, was, first, is, from, raccoon, were, live, market, for, found, as, tested, positive"
2993,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.173913043,"the, of, cases, to, a, and, huanan, market"
2994,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.173913043,"the, pandemic, is, natural, sars-cov-2, to, a, virus"
2995,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","expended to make the simple point 

that COVID-19 had a natural origin.",0.173913043,"the, to, that, had"
2996,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.173913043,"is, that, the, most, likely, sars-cov-2, to, a"
2997,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.173913043,"sars-cov-2, a, that, is"
2998,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.173913043,"the, shows, that, sars-cov-2, protein, is, in, of"
2999,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.173913043,"one, 96.2%, to, a, genome, sequence, was, bat"
3000,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.173913043,"is, that, the, hosts, for, as, a, bat"
3001,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.173913043,"the, is, in, to"
3002,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.173913043,"the, natural, reservoir, of"
3003,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","t some virus detected in pangolins 

were capable of infecting humans.",0.173913043,"in, of, pangolins, were"
3004,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.173913043,"was, of, sars-cov-2, the"
3005,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.173913043,"bat, to, sars-cov-2, found"
3006,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.173913043,"that, sars-cov-2, to, from"
3007,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.173913043,"the, fact, that, has, been, origin, is, by"
3008,"Bats are natural hosts of many of the known  

coronaviruses","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.173913043,"natural, of, the, coronaviruses"
3009,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.173913043,"are, the, whole, genome, that, bats, hosts, for"
3010,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.173913043,"the, sars-cov-2, to, is, most, likely, a, that"
3011,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.173913043,"that, the, is, bat, a, as, hosts, for"
3012,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.173913043,"genome, to, bat, sequence, was, 96.2%, a, one"
3013,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.173913043,"also, a, for, the, of, is, and, in, their, to, receptor, an"
3014,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.173913043,"pangolin, shown, to, sars-cov-2"
3015,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.173913043,"the, whole, genome, that, bats, are, hosts, for"
3016,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.173913043,"to, sars-cov-2, is, that, originated, and, the, pangolin"
3017,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.173913043,"the, that, sars-cov-2, to, bat, cov, ratg13, pangolin"
3018,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.173913043,"in, the, is, to, sars-cov-2, pangolin, cov, which"
3019,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.173913043,"the, similarity, between, sars-cov-2, and, is, that, bat"
3020,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.173913043,"that, sars-cov-2, or, in"
3021,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.173913043,"have, that, may, sars-cov-2"
3022,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.173913043,"the, origin, of, sars-cov-2, as, sarbecovirus, pangolins, and"
3023,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.173913043,"provide, evidence, for, and, that, the, of, sars-cov-2"
3024,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.173913043,"sars-cov-2, bat, cov, ratg13, pangolin, to, the, that"
3025,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.173913043,"provide, evidence, that, the, of, and, for, sars-cov-2"
3026,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.173913043,"previous, studies, the, and, reservoir, for, sars-cov, mers-cov"
3027,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.173913043,"identical, to, sars-cov-2, in"
3028,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.173913043,"in, the, are, and"
3029,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.173913043,"the, of, suggesting, that, sars-cov-2, was, transmitted, to"
3030,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.173913043,"the, virus, which, is, to, identical, that, of"
3031,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.173913043,"sars-cov-2, is, to, in, the, cov, pangolin, which"
3032,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.173913043,"the, of, at, that, sars-cov-2, is, virus, in"
3033,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.173913043,"that, is, from, to"
3034,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.173913043,"sars-cov-2, from, that, is"
3035,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.173913043,"is, to, be, likely"
3036,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.173913043,"sars-cov-2, from, that, to"
3037,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.173913043,"a, between, sars-cov-2, and"
3038,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.173913043,"in, the, of, is, sars-cov-2, at, that, virus"
3039,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.173913043,"genome, has, identity, with, the, in, yunnan, province,"
3040,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.173913043,"its, in, the, of, sequence, to, ratg13, rbd"
3041,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.173913043,"to, that, related, bat, in, and, southeast, including"
3042,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.173076923,"and, a, sars-cov-2, in, which, viral, viruses, to, human"
3043,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.173076923,"the, of, and, have, that, sars-cov-2, animal, to, humans"
3044,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.173076923,"between, humans, and, that, of, sars-cov-2, to, animal, be"
3045,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.173076923,"a, seafood, market, in, hubei, province,, china, to, were"
3046,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.173076923,"coronaviruses, to, sars-cov-2, found, in, south, and, china, from"
3047,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.173076923,"from, two, lineage, the, of, that, a, sars-cov-2, to"
3048,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.173076923,"a, two, to, that, the, of, sars-cov-2, from, lineage"
3049,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.173076923,"the, from, that, to, a, bat, and, pangolin, coronavirus"
3050,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.173076923,"the, of, to, that, have, humans, and, animal, sars-cov-2"
3051,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.173076923,"was, that, the, sars-cov-2, and, to, which, is, by"
3052,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.173076923,"the, and, that, sars-cov-2, is, which, was, to, by"
3053,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.173076923,"of, be, to, that, between, humans, and, animal, sars-cov-2"
3054,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.173076923,"a, genome, was, at, in, that, the, to, of"
3055,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.173076923,"the, of, that, sars-cov-2, more, to, a, with, than"
3056,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.173076923,"the, sars-cov-2, are, more, to, a, with, bat, than"
3057,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.173076923,"sars-cov-2, from, to, and, coronaviruses, found, in, china, south"
3058,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.173076923,"have, that, bats, are, the, reservoir, for, of, and"
3059,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.173076923,"other, that, are, also, to, a, the, origin, of"
3060,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.173076923,"the, a, to, that, coronavirus, from, pangolin, and, bat"
3061,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.173076923,"were, to, a, seafood, market, in, hubei, province,, china"
3062,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.173076923,"a, in, the, genome, that, was, to, of, at"
3063,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.173076923,"human, and, sars-cov-2, to, in, a, viral, which, viruses"
3064,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.173076923,"bat, cov, the, same, are, sars-cov-2, cluster, with, ratg13"
3065,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.173076923,"that, the, bats, hosts, for, are, more, sars-cov-2, than"
3066,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.173076923,"bat, cov, ratg13, the, same, cluster, with, sars-cov-2, are"
3067,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.173076923,"the, that, bats, are, more, hosts, for, sars-cov-2, than"
3068,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.173076923,"a, of, the, also, are, that, other, to, origin"
3069,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.173076923,"the, of, more, than, to, that, sars-cov-2, with, a"
3070,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.173076923,"are, a, to, more, with, sars-cov-2, than, the, bat"
3071,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.173076923,"that, bats, are, the, reservoir, of, and, have, for"
3072,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.172839506,"and, with, from, wuhan, to, at, the, huanan, seafood, market, of, on, a, was"
3073,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.172839506,"the, was, from, a, at, huanan, seafood, market, and, to, of, wuhan, on, with"
3074,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.172413793,"bats, as, the, viruses, sars"
3075,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.172413793,"the, animal, reservoir, be, of"
3076,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.172413793,"more, than, to, sars-cov-2, in"
3077,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.172413793,"sars-cov-2, in, to, more, than"
3078,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.172413793,"of, also, the, emergence, in"
3079,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.172413793,"bat, cov, is, to, sars-cov-2"
3080,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.172413793,"sars-cov-2, genome, to, sars-cov, mers-cov"
3081,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.172413793,"sars-cov-2, are, similar, to, of"
3082,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.172413793,"the, as, intermediate, for, sars-cov-2"
3083,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.172413793,"the, to, in, wet, of, large, china,, is, on, likely, that, infected, were, animal, market"
3084,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.172413793,"a, coronavirus, the, to, sars-cov-2"
3085,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.172413793,"to, is, and, be, the"
3086,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.172413793,"the, of, sars-cov-2, is, and"
3087,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.172413793,"from, was, at, in, wuhan, province,, the, is, to, previously"
3088,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.172413793,"the, of, coronaviruses, including, which"
3089,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.172413793,"that, in, the, of, sars-cov-2"
3090,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.172413793,"that, the, in, and, to, humans, from, animals, at, a"
3091,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.172413793,"bats, to, be, the, of"
3092,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.172413793,"the, of, sars-cov-2, to, be"
3093,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.172413793,"the, in, that, which, by"
3094,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.172413793,"the, most, probable, of, sars-cov-2"
3095,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.172413793,"the, of, sars-cov-2, are, and"
3096,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.172413793,"sars-cov-2, are, the, of, infection"
3097,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.172413793,"sars-cov-2, that, are, to, and"
3098,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.172413793,"is, that, a, sars-cov-2, or"
3099,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.172413793,"from, a, that, is, in"
3100,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.172413793,"the, virus, is, and, that"
3101,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.172413793,"the, host, was, of, family,"
3102,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.172413793,"the, of, family,, was, host"
3103,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.172413793,"a, in, the, with, of"
3104,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.172413793,"a, possible, with, the, in"
3105,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.172413793,"that, from, bats, to, intermediate, is, a, pangolin, sars-cov-2, the"
3106,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.172413793,"a, using, from, was, that, the, virus, is, to, bats"
3107,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.172413793,"that, a, of, pangolin, virus, with, to, and, the, for"
3108,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.172413793,"sars-cov-2, to, a, coronavirus, the"
3109,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.172413793,"the, similarity, sars-cov-2, with, to"
3110,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.172413793,"the, to, sars-cov-2, and, pangolin-cov"
3111,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.172413793,"of, and, to, be, the"
3112,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.172413793,"of, the, and, bat, human"
3113,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.172413793,"bat, and, to, the, of"
3114,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.172413793,"in, the, a, that, from, animals, to, humans, at, and"
3115,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.172413793,"that, the, is, a, engineered"
3116,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.172413793,"that, the, and, virus, is"
3117,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.172413793,"in, the, that, similar, to"
3118,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.172413793,"in, similar, to, that, the"
3119,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.172413793,"the, identity, of, is, and"
3120,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.172413793,"with, the, of, as, a, natural, for, it, shares, and"
3121,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.172413793,"the, by, was, a, at, huanan, seafood, market, and, to, hospital, of, on, december, with"
3122,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.172413793,"the, of, sars-cov-2, identical, to"
3123,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.172413793,"the, sars-cov-2, evolutionary, of, to"
3124,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.172413793,"phylogenetic, to, bat, sars-like, covs."
3125,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.172413793,"sars-, cov-2, bats, reservoir, its"
3126,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.172413793,"animal, species, sars-cov-2, and, the"
3127,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.172413793,"the, of, bats, be, to"
3128,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.172413793,"from, bats, to, be, the"
3129,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.172413793,"the, of, bat, and, human"
3130,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.172413793,"sars-cov-2, is, a, virus, that"
3131,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.172413793,"that, is, in, from, a"
3132,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.172413793,"the, of, that, genomes, are, to, a, bat, ratg13, genome"
3133,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.172413793,"the, are, sars-cov-2, and, of"
3134,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.172413793,"are, the, hosts, of, and"
3135,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.172413793,"bats, are, the, likely, of"
3136,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.172413793,"a, in, the, of, with"
3137,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.172413793,"the, similar, to, that, in"
3138,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.172413793,"the, are, sars-cov-2, infection, of"
3139,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.172413793,"of, be, the, reservoir, animal"
3140,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.172413793,"natural, in, the, for, of"
3141,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.172413793,"between, and, the, of, sars-cov-2"
3142,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.172413793,"a, for, the, as, natural, of, and, it, shares, with"
3143,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.172413793,"sars-cov, mers-cov, sars-cov-2, to, genome"
3144,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.172413793,"a, in, the, possible, with"
3145,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.172413793,"the, that, sars-cov-2, is, to"
3146,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.172413793,"in, to, that, sars-cov-2, the"
3147,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.172413793,"to, sars-cov-2, is, a, that, from, bats, the, pangolin, intermediate"
3148,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.172413793,"that, is, similar, to, the"
3149,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.172413793,"zoonotic, from, an, as, the"
3150,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.172413793,"sars-cov-2, the, species, and, animal"
3151,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.172413793,"including, coronaviruses, the, which, of"
3152,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.172413793,"the, sars, as, viruses, bats"
3153,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.172413793,"the, to, of, bat, and"
3154,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.172413793,"a, the, huanan, seafood, with, at, was, on, december, and, market, of, to, hospital, by"
3155,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.172413793,"on, the, large, of, infected, that, were, to, wet, animal, market, in, china,, is, likely"
3156,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.172413793,"is, that, a, sars-cov-2, through"
3157,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.172413793,"it, is, that, sars-cov-2, a"
3158,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.172413793,"data, the, that, is, virus"
3159,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.172413793,"sars-, cov-2, its, reservoir, bats"
3160,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.172413793,"the, by, which, that, in"
3161,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.172413793,"that, is, the, most, of"
3162,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.172413793,"is, to, be, and, the"
3163,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.172413793,"the, data, that, is, virus"
3164,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.172413793,"is, that, sars-cov-2, through, a"
3165,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.172413793,"the, zoonotic, from, an, as"
3166,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.172413793,"was, found, the, 96.2%, genome"
3167,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.172413793,"that, are, to, sars-cov-2, and"
3168,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.172413793,"the, of, sars-cov-2, be, to"
3169,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.172413793,"the, to, similarity, with, sars-cov-2"
3170,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.172413793,"the, also, in, emergence, of"
3171,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.172413793,"is, at, the, to, was, previously, in, from, province,, wuhan"
3172,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.172413793,"to, is, a, virus, that, from, bats, was, using, the"
3173,"According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.172413793,"to, phylogenetic, sars-like, bat, covs."
3174,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.172413793,"the, virus, for, a, of, to, with, that, pangolin, and"
3175,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.172413793,"sars-cov-2, is, to, bat, cov"
3176,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.172413793,"of, sars-cov-2, are, similar, to"
3177,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.172413793,"the, genome, of, bat, that, a, genomes, ratg13, are, to"
3178,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.172413793,"is, the, with, and, sars-cov-2"
3179,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.172413793,"sars-cov-2, is, of, and, the"
3180,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.172413793,"is, the, and, of, identity"
3181,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.172413793,"the, that, sars-cov-2, in, of"
3182,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.172413793,"the, of, sars-cov-2, between, and"
3183,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.172413793,"the, of, are, hosts, and"
3184,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.172413793,"the, sars-cov-2, is, with, and"
3185,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.172413793,"the, and, sars-cov-2, to, in"
3186,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.172413793,"the, are, to, sars-cov-2, and"
3187,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.172413793,"to, sars-cov-2, the, pangolin-cov, and"
3188,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.172413793,"sars-cov-2, to, the, in, and"
3189,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.172413793,"the, natural, of, in, for"
3190,"According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.172413793,"to, the, evolutionary, sars-cov-2, of"
3191,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.172413793,"the, sars-cov-2, as, intermediate, for"
3192,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.172413793,"of, that, is, most, the"
3193,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.172413793,"the, genome, was, found, 96.2%"
3194,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.172413793,"the, that, in, to, sars-cov-2"
3195,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.172413793,"is, that, the, engineered, a"
3196,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.171875,"and, a, of, between, sars-cov-2, in, which, is, the, to, human"
3197,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.171875,"to, suggest, that, the, and, pangolins, may, hosts, for, sars-cov-2, than"
3198,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.171875,"the, between, sars-cov-2, and, which, to, a, of, is, in, human"
3199,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.171875,"in, with, the, to, sars-cov-2, is, bat, cov, ratg13, guangdong, pangolin"
3200,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.171875,"sars-cov-2, is, to, in, the, with, bat, cov, ratg13, guangdong, pangolin"
3201,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.171875,"suggest, that, and, may, hosts, for, sars-cov-2, to, than, pangolins, the"
3202,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.171641791,"the, to, in, a, for, of, as, researchers, large, viruses, horseshoe, bats,, with, southern, sars, that, multiple, bats, progenitor, virus, were, by, and"
3203,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.171641791,"by, the, of, a, large, viruses, in, multiple, horseshoe, bats,, to, that, sars, bats, with, as, and, progenitor, were, researchers, virus, for, southern"
3204,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.171428571,"more, than, bats, of, α-, and"
3205,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.171428571,"sars-cov, and, sars-cov-2, to, in, of"
3206,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.171428571,"and, bats, of, more, than, α-"
3207,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.171428571,"sars-cov-2, shares, with, that, and, is"
3208,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.171428571,"the, to, of, bat, and, human"
3209,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.171428571,"sars-cov-2, is, to, a, of, the"
3210,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.171428571,"to, the, sequence, a, sars-cov-2, is"
3211,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.171428571,"is, that, the, was, of, a"
3212,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.171428571,"of, natural, origin, has, as, and"
3213,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.171428571,"sars-cov, and, sars-cov-2, in, to, of"
3214,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.171428571,"sars-cov-2, the, of, sequence, with, sars-cov"
3215,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.171428571,"bat, in, genome, of, with, sars-cov-2"
3216,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.171428571,"of, the, sequence, and, sars-cov-2, is"
3217,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.171428571,"is, that, the, virus, was, a"
3218,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.171428571,"from, to, humans, for, the, spillover"
3219,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.171428571,"the, of, sars-cov-2, is, to, a"
3220,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.171428571,"to, the, of, be, a, spillover"
3221,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.171428571,"with, the, sars-cov, sars-cov-2, of, sequence"
3222,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.171428571,"the, sequence, sars-cov-2, is, to, a"
3223,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.171428571,"the, animals, in, to, and, spread"
3224,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.171428571,"the, outbreak, from, animals, in, humans"
3225,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.171428571,"bat, that, the, of, sars-cov-2, lineage"
3226,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.171428571,"sars-cov-2, shares, with, and, is, that"
3227,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.171428571,"the, that, to, sars-cov-2, and, of"
3228,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.171428571,"the, genome, to, bat, and, that"
3229,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.171428571,"of, to, that, sars-cov-2, the, and"
3230,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.171428571,"to, and, can, the, of, sars-cov-2"
3231,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.171428571,"the, bats, to, of, sars-cov-2, and"
3232,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.171428571,"the, bats, and, transmitted, to, of"
3233,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","with the first case being linked to  

a seafood market",0.171428571,"the, a, seafood, market, to, with"
3234,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.171428571,"the, by, that, originated, and, a"
3235,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.171428571,"that, the, sars-cov-2, as, to, a"
3236,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.171428571,"the, that, sars-cov-2, lineage, of, bat"
3237,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.171428571,"the, of, sars-cov-2, that, and, to"
3238,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.171428571,"the, of, and, are, to, that"
3239,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.171428571,"the, of, with, huanan, market, in"
3240,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.171428571,"the, of, animal, hosts, and, other"
3241,"In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.171428571,"in, to, viruses, more, than, human"
3242,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.171428571,"that, the, virus, was, as, a"
3243,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.171428571,"that, the, virus, coronavirus, and, to"
3244,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.171428571,"the, were, that, virus, animals, and"
3245,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.171428571,"the, genome, that, and, to, bat"
3246,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.171428571,"that, the, very, to, a, bat"
3247,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.171428571,"the, a, from, intermediate, as, to"
3248,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.171428571,"the, sars-cov-2, coronavirus, has, been, from"
3249,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.171428571,"sars-cov-2, has, the, with, similarity, to"
3250,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.171428571,"the, of, sars-cov-2, and, can, to"
3251,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.171428571,"that, a, virus, has, of, sars-cov-2"
3252,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.171428571,"of, sars-cov-2, has, that, the, a"
3253,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.171428571,"the, and, of, bat, to, human"
3254,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.171428571,"to, the, of, and, is, be"
3255,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.171428571,"scientists, through, that, the, of, to"
3256,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.171428571,"was, that, the, of, is, a"
3257,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.171428571,"a, is, the, that, virus, was"
3258,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.171428571,"the, virus, was, as, a, that"
3259,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.171428571,"that, were, the, and, animals, virus"
3260,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.171428571,"the, virus, is, to, that, and"
3261,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.171428571,"to, is, virus, that, and, the"
3262,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.171428571,"the, is, that, virus, to, and"
3263,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.171428571,"animal, and, in, the, that, to"
3264,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.171428571,"to, that, the, origin, and, is"
3265,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.171428571,"the, that, is, virus, in, animal"
3266,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.171428571,"to, the, of, may, be, because"
3267,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.171428571,"the, of, to, is, that, bats"
3268,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.171428571,"the, that, of, virus, and, to"
3269,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.171428571,"the, of, identity, to, that, bats"
3270,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.171428571,"that, the, of, has, been, from"
3271,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.171428571,"to, the, from, for, spillover, humans"
3272,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.171428571,"in, from, of, bats, to, the"
3273,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.171428571,"from, species, sars-cov-2, and, the, humans"
3274,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.171428571,"the, to, that, had, virus, and"
3275,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.171428571,"the, virus, coronavirus, that, and, to"
3276,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.171428571,"and, that, the, virus, to, of"
3277,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.171428571,"analysis, that, the, sars-cov-2, a, laboratory"
3278,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.171428571,"the, in, and, spread, to, animals"
3279,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.171428571,"the, outbreak, in, humans, from, animals"
3280,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.171428571,"in, animals, and, transmitted, to, humans"
3281,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.171428571,"this, is, sars-cov-2, bat, that, in"
3282,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.171428571,"that, a, genome, of, with, sars-cov-2"
3283,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.171428571,"analysis, of, the, that, and, sars-cov-2"
3284,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.171428571,"other, and, the, of, animal, hosts"
3285,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.171428571,"of, that, similar, to, the, was"
3286,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.171428571,"at, was, in, the, with, genome"
3287,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.171428571,"is, that, a, of, sars-cov-2, the"
3288,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.171428571,"that, sars-cov-2, a, hypothesis, the, of"
3289,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.171428571,"was, in, yunnan, the, horseshoe, bat"
3290,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.171428571,"the, was, in, horseshoe, bat, yunnan"
3291,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.171428571,"in, the, of, a, was, and"
3292,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.171428571,"and, a, natural, origin, of, the"
3293,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.171428571,"sars-cov-2, and, a, the, origin, of"
3294,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K",0.171428571,"human, viruses, in, more, to, than"
3295,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.171428571,"to, be, a, spillover, of, the"
3296,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.171428571,"the, may, be, because, of, to"
3297,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.171428571,"the, is, sars-cov-2, to, related, in"
3298,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.171428571,"with, sars-cov-2, bat, in, of, genome"
3299,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.171428571,"a, of, has, that, sars-cov-2, virus"
3300,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.171428571,"a, of, sars-cov-2, genome, with, that"
3301,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.171428571,"the, and, sars-cov-2, is, of, sequence"
3302,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.171428571,"analysis, of, the, sars-cov-2, that, and"
3303,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.171428571,"the, of, in, to, from, bats"
3304,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.171428571,"sars-cov-2, the, species, and, humans, from"
3305,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.171428571,"the, a, as, to, spillover, from"
3306,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.171428571,"to, a, from, the, as, intermediate"
3307,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.171428571,"were, related, to, in, and, china"
3308,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.171428571,"the, that, are, to, and, of"
3309,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.171428571,"the, of, through, to, that, scientists"
3310,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.171428571,"is, the, known, to, be, in"
3311,"with the first case being linked to  

a seafood market","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.171428571,"with, the, to, a, seafood, market"
3312,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.171428571,"the, to, and, that, in, animal"
3313,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.171428571,"and, related, to, were, in, china"
3314,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.171428571,"natural, in, and, the, new, of"
3315,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.171428571,"is, that, the, bats, of, to"
3316,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.171428571,"we, that, in, the, of, sars-cov-2"
3317,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.171428571,"the, of, bats, and, transmitted, to"
3318,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.171428571,"in, and, transmitted, to, humans, through"
3319,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.171428571,"animals, in, transmitted, to, humans, and"
3320,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.171428571,"the, that, was, similar, to, of"
3321,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.171428571,"was, similar, to, that, of, the"
3322,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.171428571,"with, of, the, huanan, market, in"
3323,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.171428571,"the, was, in, and, a, of"
3324,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.171428571,"the, covid-19, a, wild, animals, is"
3325,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.171428571,"a, the, covid-19, is, wild, animals"
3326,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.171428571,"that, a, of, the, virus, is"
3327,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.171428571,"of, a, analysis, that, the, virus"
3328,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.171428571,"a, of, has, that, sars-cov-2, the"
3329,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.171428571,"the, natural, origin, of, a, and"
3330,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.171428571,"and, has, as, natural, of, origin"
3331,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.171428571,"sars-cov-2, and, ratg13, to, viruses, that"
3332,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.171428571,"the, sars-cov-2, with, of, similarity, to"
3333,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.171428571,"sars-cov-2, sequences, their, and, bat, of"
3334,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.171428571,"the, is, to, and, that, origin"
3335,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.171428571,"to, the, that, sars-cov-2, as, a"
3336,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.171428571,"the, to, bat, that, a, very"
3337,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.171428571,"analysis, of, the, that, a, virus"
3338,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.171428571,"and, that, in, the, of, sars-cov-2"
3339,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.171428571,"is, the, sars-cov-2, we, believe, that"
3340,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.171428571,"we, believe, that, sars-cov-2, is, the"
3341,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.171428571,"coronavirus, from, the, has, been, sars-cov-2"
3342,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.171428571,"has, been, that, the, of, from"
3343,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.171428571,"sars-cov-2, that, is, in, this, bat"
3344,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.171428571,"sars-cov-2, viruses, that, to, ratg13, and"
3345,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.171428571,"the, of, this, indicates, that, sars-cov-2"
3346,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.171428571,"sequences, of, sars-cov-2, and, their, bat"
3347,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.171428571,"sars-cov-2, and, bat, pangolin, the, of"
3348,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.171428571,"we, between, and, that, the, sars-cov-2"
3349,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.171428571,"the, origin, of, sars-cov-2, a, and"
3350,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.171428571,"sars-cov-2, the, with, of, and, pangolin-cov"
3351,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.171428571,"the, in, of, that, sars-cov-2, we"
3352,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.171428571,"of, the, in, and, that, sars-cov-2"
3353,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.171428571,"we, that, the, between, sars-cov-2, and"
3354,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.171428571,"a, are, for, including, the, and"
3355,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.171428571,"in, the, pangolin-cov, identical, to, sars-cov-2"
3356,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.171428571,"of, in, natural, and, the, new"
3357,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.171428571,"in, this, that, the, and, of"
3358,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.171428571,"the, similarity, of, sars-cov-2, with, to"
3359,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.171428571,"this, that, in, and, the, of"
3360,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.171428571,"that, the, bats, of, identity, to"
3361,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.171428571,"the, to, identical, in, sars-cov-2, pangolin-cov"
3362,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.171428571,"the, virus, is, that, in, animal"
3363,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.171428571,"this, indicates, that, the, of, sars-cov-2"
3364,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.171428571,"are, the, for, a, including, and"
3365,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.171428571,"in, the, with, genome, was, at"
3366,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.171428571,"is, the, to, known, be, in"
3367,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.171428571,"the, sars-cov-2, and, bat, pangolin, of"
3368,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.171428571,"the, analysis, that, sars-cov-2, a, laboratory"
3369,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.170731707,"human, viruses, in, closely, related, to, other"
3370,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.170731707,"sars-cov-2, from, a, virus, that, is, in"
3371,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.170731707,"sars-cov-2, to, have, the, host, with, bat"
3372,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.170731707,"the, that, sars-cov-2, to, with, bat, genome"
3373,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.170731707,"the, to, sars-cov-2, genome,, in, of, bat"
3374,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.170731707,"that, the, closest, virus, and, similarity, to"
3375,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.170731707,"from, of, bats, to, sars-cov-2, the, humans"
3376,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.170731707,"this, is, origin, of, the, market, in"
3377,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.170731707,"that, is, covid-19, in, wuhan, animal, to"
3378,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.170731707,"the, of, be, to, and, animal, sars-cov-2"
3379,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.170731707,"is, sars-cov-2, and, bat, to, the, that"
3380,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.170731707,"the, of, is, identical, to, sars-cov-2, that"
3381,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.170731707,"evidence, to, the, sars-cov-2, of, humans, from"
3382,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.170731707,"the, hypothesis, that, virus, a, it, been"
3383,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.170731707,"the, sars-cov-2, to, humans, from, evidence, of"
3384,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.170731707,"of, the, two, that, sars-cov-2, a, viruses"
3385,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.170731707,"that, sars-cov-2, are, to, a, the, of"
3386,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.170731707,"the, earliest, cases, in, to, huanan, market"
3387,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.170731707,"the, of, market, in, is, this, origin"
3388,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.170731707,"human, closely, related, to, in, other, viruses"
3389,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.170731707,"huanan, market,, the, was, and, of, there."
3390,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.170731707,"of, cases, to, the, huanan, market,, that"
3391,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.170731707,"that, to, animal, in, wuhan, is, covid-19"
3392,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.170731707,"that, samples, from, the, huanan, seafood, animals"
3393,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.170731707,"the, that, to, a, bat, and, coronavirus"
3394,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.170731707,"96.2%, to, a, genome, sequence, was, bat"
3395,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.170731707,"the, of, were, with, huanan, market, in"
3396,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.170731707,"is, that, sars-cov-2, the, and, humans, animal"
3397,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.170731707,"from, infected, animals, in, the, market, have"
3398,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.170731707,"a, virus, from, animals, to, humans, the"
3399,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.170731707,"that, jumped, the, and, infected, humans, from"
3400,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.170731707,"of, the, huanan, market,, and, was, there."
3401,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.170731707,"have, the, in, from, infected, animals, market"
3402,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.170731707,"the, to, bat, is, that, bats, reservoir"
3403,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.170731707,"that, the, virus, of, and, to, betacoronavirus"
3404,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.170731707,"genetic, and, that, of, is, most, likely"
3405,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.170731707,"the, virus, to, humans, from, animals, a"
3406,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.170731707,"the, and, that, sars-cov-2, is, animal, humans"
3407,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.170731707,"that, the, and, jumped, humans, from, infected"
3408,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.170731707,"the, and, betacoronavirus, of, virus, to, that"
3409,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.170731707,"showed, the, of, genome, bat, coronavirus, covid-19"
3410,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.170731707,"that, the, covid-19, virus, and, to, of"
3411,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.170731707,"that, has, the, of, virus, and, to"
3412,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.170731707,"is, that, sars-cov-2, from, a, virus, in"
3413,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.170731707,"in, virus, is, that, sars-cov-2, this, a"
3414,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.170731707,"samples, that, from, the, huanan, seafood, animals"
3415,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.170731707,"a, hypothesis, that, the, virus, it, been"
3416,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.170731707,"the, that, of, has, been, is, a"
3417,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.170731707,"the, was, to, that, in, with, of"
3418,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.170731707,"of, the, cases, to, huanan, market,, that"
3419,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.170731707,"the, genome,, sars-cov-2, to, bat, in, of"
3420,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.170731707,"the, of, as, a, natural, from, and"
3421,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.170731707,"found, the, of, ratg13, to, sars-cov-2, in"
3422,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.170731707,"the, natural, of, as, a, from, and"
3423,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.170731707,"which, in, rhinolophus, the, with, identity, genome"
3424,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.170731707,"the, is, that, a, of, has, been"
3425,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.170731707,"found, in, the, of, sars-cov-2, to, ratg13"
3426,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.170731707,"in, et, al., (2020), found, of, to"
3427,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.170731707,"to, the, of, sars-cov-2, from, bats, humans"
3428,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.170731707,"in, the, earliest, cases, to, huanan, market"
3429,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.170731707,"the, sars-cov-2, is, to, bat, whole, genome"
3430,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.170731707,"that, with, the, of, have, to, sars-cov-2."
3431,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.170731707,"is, that, a, wildlife, sars-cov-2, to, through"
3432,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.170731707,"that, is, to, bat, bats, the, reservoir"
3433,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.170731707,"that, sars-cov-2, also, similar, to, the, of"
3434,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.170731707,"of, the, genome, covid-19, showed, bat, coronavirus"
3435,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.170731707,"and, that, the, covid-19, virus, to, of"
3436,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.170731707,"to, is, virus, that, and, was, the"
3437,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.170731707,"to, that, the, most, of, and, is"
3438,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.170731707,"the, of, were, in, with, huanan, market"
3439,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.170731707,"in, the, with, that, was, to, of"
3440,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.170731707,"sars-cov-2, is, a, that, through, wildlife, to"
3441,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.170731707,"genetic, and, that, is, most, likely, of"
3442,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.170731707,"of, a, suggest, that, the, virus, and"
3443,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.170731707,"of, that, is, most, to, the, and"
3444,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.170731707,"the, to, bat, coronavirus, and, that, a"
3445,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.170731707,"and, suggest, that, a, of, the, virus"
3446,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.170731707,"genome, to, bat, sequence, was, 96.2%, a"
3447,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.170731707,"et, al., (2020), found, of, to, in"
3448,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.170731707,"a, viruses, two, that, the, of, sars-cov-2"
3449,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.170731707,"that, sars-cov-2, sequences, and, a, the, of"
3450,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.170731707,"the, sars-cov-2, that, and, is, to, bat"
3451,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.170731707,"have, sars-cov-2, to, with, bat, the, host"
3452,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.170731707,"sequences, the, probable, bat, origin, of, and"
3453,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.170731707,"that, sars-cov-2, also, pangolin, cov, and, the"
3454,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.170731707,"the, sequences, and, probable, bat, origin, of"
3455,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.170731707,"a, are, to, that, the, of, sars-cov-2"
3456,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.170731707,"the, of, similar, to, that, sars-cov-2, also"
3457,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.170731707,"of, the, and, that, sars-cov-2, sequences, a"
3458,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.170731707,"also, that, the, sars-cov-2, and, cov, pangolin"
3459,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.170731707,"that, sars-cov-2, to, with, genome, bat, the"
3460,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.170731707,"the, of, sars-cov-2, that, is, identical, to"
3461,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.170731707,"the, rhinolophus, which, in, identity, with, genome"
3462,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.170731707,"have, that, the, of, with, to, sars-cov-2."
3463,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.17037037,"to, a, however,, as, civets, in, multiple, chinese, for, the, virus, or, by, southern, china, sars, were, of, and, also, bats,, species, horseshoe"
3464,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.17037037,"by, the, of, a, in, multiple, species, horseshoe, bats,, to, sars, civets, as, and, however,, or, were, virus, also, for, chinese, southern, china"
3465,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.170212766,"the, that, sars-cov-2, to, bat, cov, ratg13, genome"
3466,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.170212766,"the, most, reservoirs, are, more, of, bats, and"
3467,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.170212766,"this, of, to, the, market, in, that, exposed"
3468,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.170212766,"the, of, is, to, that, sars-cov-2, with, and"
3469,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.170212766,"in, humans, through, is, the, be, identified, sars-cov-2"
3470,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.170212766,"of, evidence, that, the, origin, a, from, as"
3471,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.170212766,"in, (39),, that, the, lineage, cases, huanan, market"
3472,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.170212766,"the, lineage, cases, huanan, market, (39),, that, in"
3473,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.170212766,"of, the, that, sars-cov-2, is, a, naturally, occurring"
3474,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.170212766,"we, evidence, event, and, that, the, of, sars-cov-2"
3475,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.170212766,"the, of, that, exposed, to, market, in, this"
3476,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.170212766,"the, by, huanan, market, of, wuhan, december, with"
3477,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.170212766,"be, a, the, that, sars-cov-2, originated, from, possibly"
3478,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.170212766,"the, virus, has, a, of, to, that, and"
3479,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.170212766,"to, of, the, virus, genetic, has, originated, and"
3480,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.170212766,"and, to, the, be, of, human, pangolin, intermediate"
3481,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.170212766,"on, and, have, shown, that, is, by, of"
3482,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.170212766,"that, and, in, who, at, a, market, china"
3483,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.170212766,"of, genetic, to, has, originated, the, and, virus"
3484,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.170212766,"of, was, shown, to, which, the, in, animals"
3485,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.170212766,"that, sars-cov-2, the, of, virus, and, similarity, to"
3486,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.170212766,"on, of, and, have, shown, that, is, by"
3487,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.170212766,"the, pangolin, to, be, of, intermediate, and, human"
3488,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.170212766,"has, revealed, identity, and, the, of, virus, bat"
3489,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.170212766,"that, in, and, who, at, a, market, china"
3490,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.170212766,"and, revealed, the, virus, has, identity, of, bat"
3491,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.170212766,"of, at, the, in, a, similar, to, that"
3492,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.170212766,"that, a, naturally, occurring, the, of, sars-cov-2, is"
3493,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.170212766,"the, is, covid-19, huanan, seafood, market, in, at"
3494,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.170212766,"the, of, sars-cov-2, with, that, and, is, to"
3495,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.170212766,"that, a, virus, in, has, of, with, sars-cov-2"
3496,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.170212766,"of, sars-cov-2, has, not, been, that, the, a"
3497,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.170212766,"this, that, in, and, the, virus, for, of"
3498,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.170212766,"in, of, virus, that, sars-cov-2, has, with, a"
3499,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.170212766,"bats, are, the, most, reservoirs, of, and, more"
3500,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.170212766,"banal, related, to, sars-cov-2,, at, the, which, is"
3501,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.170212766,"the, banal, are, closely, related, to, sars-cov-2, by"
3502,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.170212766,"by, closely, related, banal, are, to, sars-cov-2, the"
3503,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.170212766,"also, similarity, of, sars-cov-2, their, the, viruses, to"
3504,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.170212766,"related, to, sars-cov-2,, is, banal, which, at, the"
3505,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.170212766,"the, identified, sars-cov-2, humans, through, in, is, be"
3506,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.170212766,"of, december, the, huanan, market, with, wuhan, by"
3507,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.170212766,"covid-19, is, at, the, huanan, seafood, market, in"
3508,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.170212766,"evidence, the, that, as, a, of, from, origin"
3509,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.170212766,"the, it, not, even, would, with, to, of"
3510,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.170212766,"is, the, amino, acid, sequence, in, of, s"
3511,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.170212766,"the, of, not, that, sars-cov-2, has, been, a"
3512,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.170212766,"in, animals, to, of, the, which, shown, was"
3513,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.170212766,"the, for, it, is, to, that, sars-cov-2, a"
3514,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.170212766,"the, viruses, also, to, sars-cov-2, similarity, of, their"
3515,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.170212766,"sars-cov-2, is, the, same, with, bat, cov, ratg13"
3516,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.170212766,"bat, cov, ratg13, is, the, same, with, sars-cov-2"
3517,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.170212766,"genome, the, to, bat, cov, ratg13, that, sars-cov-2"
3518,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.170212766,"that, event, the, of, sars-cov-2, and, evidence, we"
3519,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.170212766,"in, the, of, virus, for, that, and, this"
3520,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.170212766,"a, in, the, that, sars-cov-2, feral, animal, for"
3521,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.170212766,"sars-cov-2, be, a, that, originated, from, possibly, the"
3522,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.170212766,"the, that, sars-cov-2, a, in, feral, animal, for"
3523,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.170212766,"even, the, not, to, it, would, with, of"
3524,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.170212766,"a, in, the, that, similar, to, of, at"
3525,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.170212766,"in, is, the, amino, acid, sequence, of, s"
3526,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.169811321,"sars-cov-2, to, a, are, genetic, and, coronaviruses, in, bat"
3527,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.169811321,"the, that, many, of, human, are, and, these, all"
3528,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.169811321,"in, the, of, is, to, sars-cov-2, has, been, this"
3529,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.169811321,"and, sars-cov-2, are, to, bat, coronaviruses, in, a, genetic"
3530,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.169811321,"the, of, coronavirus, that, from, wuhan, was, bat, and"
3531,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.169811321,"indicated, the, from, a, market, live, animals, in, and"
3532,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.169811321,"that, the, from, a, animals, in, to, humans, spread"
3533,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.169811321,"a, sequence, and, bat, high, to, 96.2%, that, coronavirus"
3534,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.169811321,"genome, sequence, between, sars-cov-2, and, the, of, virus, bat"
3535,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.169811321,"and, that, from, the, bat, coronavirus, was, wuhan, of"
3536,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.169811321,"in, the, market, live, from, and, a, indicated, animals"
3537,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.169811321,"from, in, humans, spread, the, that, a, animals, to"
3538,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.169811321,"the, between, sars-cov-2, and, of, genome, sequence, virus, bat"
3539,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.169811321,"to, bat, coronavirus, and, that, sequence, 96.2%, a, high"
3540,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.169811321,"the, sars-cov-2, has, been, to, in, of, this, is"
3541,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.169811321,"that, the, beta, able, to, infect, mice, and, in"
3542,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.169811321,"in, the, beta, and, able, to, that, infect, mice"
3543,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.169811321,"the, and, are, all, of, that, many, these, human"
3544,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.169811321,"the, sars-cov-2, to, is, most, natural, on, a, that"
3545,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.169811321,"sars-cov-2, is, a, natural, that, on, to, the, most"
3546,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.169491525,"market, in, wuhan, city,, that, the, is, to, of, were"
3547,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.169491525,"of, from, bats, to, humans, is, found, in, sars-cov-2, the"
3548,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.169491525,"the, of, virus, for, to, that, has, with, and, a"
3549,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.169491525,"the, virus, for, has, a, of, to, with, that, and"
3550,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.169491525,"the, of, sars-cov-2, to, human, is, a, that, this, not"
3551,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.169491525,"the, sars-cov-2, to, humans, from, bats, in, of, is, found"
3552,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.169491525,"the, and, that, sars-cov-2, is, part, of, shows, sars-, cov-2"
3553,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.169491525,"coronaviruses, that, to, sars-cov-2, in, rhinolophus, bats, south, and, from"
3554,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.169491525,"to, sars-cov-2, from, in, rhinolophus, bats, and, south, that, coronaviruses"
3555,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.169491525,"the, of, is, not, to, that, sars-cov-2, human, this, a"
3556,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.169491525,"the, of, that, were, to, market, in, wuhan, city,, is"
3557,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.169491525,"to, that, the, is, bats, are, very, likely, hosts, sars-cov-2"
3558,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.169491525,"of, the, sars-, cov-2, shows, that, and, sars-cov-2, is, part"
3559,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.169491525,"is, that, bats, are, the, likely, hosts, sars-cov-2, very, to"
3560,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.169230769,"sars-cov-2, have, to, a, genetic, between, and, coronaviruses, found, in, bat"
3561,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.169230769,"between, sars-cov-2, and, have, to, a, genetic, found, in, bat, coronaviruses"
3562,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.169230769,"that, and, may, intermediate, hosts, for, sars-cov-2, the, interaction, in, with"
3563,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.169230769,"sars-cov-2, may, in, and, that, the, interaction, with, intermediate, hosts, for"
3564,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.169230769,"the, of, raccoon, dogs, intermediate, host, that, from, in, taken, this"
3565,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.169230769,"the, of, raccoon, dogs, in, taken, from, that, this, intermediate, host"
3566,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.169230769,"sars-cov-2, of, on, the, with, similar, in, virus, binding, s, protein"
3567,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.169230769,"virus, in, similar, with, sars-cov-2, the, of, binding, s, protein, on"
3568,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.169014085,"the, of, lineage, b, and, early, that, sars-cov-2, into, humans, at, in"
3569,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.169014085,"of, the, lineage, that, early, sars-cov-2, and, at, in, b, into, humans"
3570,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.168831169,"in, the, of, researchers, a, to, as, by, with, coronaviruses, viruses, sars,, sars-related, were, sufficiently, similar, and, that, sars, it, years, locate, viral, multiple, species, horseshoe"
3571,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.168831169,"by, the, of, a, sars-related, viruses, in, multiple, species, horseshoe, to, that, sars, with, as, and, locate, sars,, were, years, researchers, sufficiently, similar, it, coronaviruses, viral"
3572,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.168539326,"for, the, of, raccoon, were, that, virus, from, a, found, in, this, likely, as, to"
3573,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.168539326,"in, a, of, to, the, likely, virus, that, this, from, raccoon, were, for, found, as"
3574,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.168539326,"from, its, into, and, it, this, was, for, by, the, of, that, sars-cov-2, in, a"
3575,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.168539326,"and, the, it, that, its, was, for, of, sars-cov-2, into, in, this, from, a, by"
3576,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.168421053,"the, huanan, wuhan, that, researchers, of, cases, identified, were, case, by, and, with, a, known, covid-19"
3577,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.168421053,"by, a, of, researchers, the, that, covid-19, cases, were, identified, wuhan, and, case, with, huanan, known"
3578,Bats are hosts of many coronaviruses,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.166666667,"are, of, coronaviruses"
3579,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.166666667,"the, are, as, in, viruses, from"
3580,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.166666667,"are, the, reservoir, of, and"
3581,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.166666667,"sars-cov, and, in, to, many"
3582,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.166666667,"in, many, to, sars-cov, and"
3583,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.166666667,"bats, more, of, sars-cov-2, than"
3584,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.166666667,"in, virus, more, than, is, to, sars-cov-2"
3585,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.166666667,"whole, genome, more, virus, than"
3586,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.166666667,"in, is, identical, to, sars-cov-2, virus"
3587,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.166666667,"such, sars-cov-2, is, to"
3588,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.166666667,"in, the, of, bats"
3589,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.166666667,"are, the, bats, in, china"
3590,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.166666667,"of, the, are, same, in"
3591,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.166666667,"it, was, the, infected, with, in, used, as, a, of"
3592,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.166666667,"it, been, that, the, of, coronaviruses, from"
3593,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.166666667,"to, sars-cov-2, from, of, sequences, the, systems, it, been, that, coronaviruses"
3594,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.166666667,"have, the, genetic, between, sars-cov-2, and, of, is, to, bat"
3595,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.166666667,"other, with, a, that, sars-cov-2, emerged"
3596,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.166666667,"is, that, sars-cov-2, a, their"
3597,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.166666667,"a, genetic, that, sars-cov-2, and, virus"
3598,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.166666667,"virus, is, that, sars-cov-2, with, and, within, a"
3599,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.166666667,"is, that, sars-cov-2, emerged, a"
3600,"Bats are natural hosts of many of the known  

coronaviruses","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.166666667,"are, of, many, the, coronaviruses"
3601,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.166666667,"research, that, bat, genome, with, sars-cov-2"
3602,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.166666667,"that, the, sars-cov-2, as, to, bat"
3603,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.166666667,"t, is, identical, the, to, ratg13,, was"
3604,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.166666667,"to, sars-cov-2, is, a, that, was, the"
3605,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.166666667,"the, is, that, to, a, of, it"
3606,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.166666667,"sars-cov-2, was, to, cov, the, of"
3607,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.166666667,"was, to, that, of, sars-cov-2, the"
3608,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.166666667,"on, virus, as, has, bat, and"
3609,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.166666667,"of, and, are, the, reservoir"
3610,"bats are also important reservoir species for a great 

range of coronaviruses","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.166666667,"are, reservoir, a, of"
3611,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.166666667,"the, virus, covid-19, genome, to, identity, that, and, bat"
3612,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.166666667,"sars-cov-2, was, that, to, ratg13, and"
3613,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.166666667,"the, known, to, sars-cov-2, and, of"
3614,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.166666667,"is, with, and, of, the, in"
3615,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.166666667,"with, bat, sars-like, and, the"
3616,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.166666667,"the, genome, of, sars-cov, and, bat, sequence, in, to"
3617,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.166666667,"sars-cov-2, to, the, in, and, of"
3618,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.166666667,"in, the, of, is, to, sars-cov-2, with, and"
3619,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.166666667,"in, with, and, to, sars-cov-2, the, whole, genome"
3620,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.166666667,"genome, in, the, bat, of, and, covs"
3621,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.166666667,"sars-cov-2, and, bat, to, the, of"
3622,"According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.166666667,"to, sars-cov-2, of"
3623,The COVID-19 most likely developed from bat origin coronaviruses,Originating from reservoir of bat,0.166666667,"from, bat"
3624,"civet cats and raccoon dogs  

are the intermediate hosts",hese reservoirs are the bats,0.166666667,"are, the"
3625,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",hese reservoirs are the bats,0.166666667,"the, are, bats"
3626,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.166666667,"the, is, that, virus, to, a, and"
3627,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.166666667,"a, in, the, that, was, to"
3628,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.166666667,"the, discovered, that, is, to"
3629,"expended to make the simple point 

that COVID-19 had a natural origin.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.166666667,"to, the, that, had, a"
3630,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.166666667,"the, of, pangolins, intermediate, hosts."
3631,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.166666667,"pangolins, were, intermediate, the, in"
3632,"According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.166666667,"to, the, sars-cov-2, close, of"
3633,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.166666667,"the, bats, to, as, of, sars-cov-2, intermediate"
3634,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.166666667,"the, bats, to, humans, intermediate, hosts, of"
3635,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.166666667,"the, origin, were, likely, to, that, in"
3636,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.166666667,"the, that, animal, of, zoonotic, origin, is"
3637,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.166666667,"of, covid-19, that, it, is, to, the"
3638,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.166666667,"the, to, this, it, that, in, people, of"
3639,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.166666667,"this, that, the, likely, origin, of"
3640,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.166666667,"and, to, were, in, china"
3641,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.166666667,"a, the, of, sars-cov-2, and, is, to, an"
3642,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.166666667,"the, of, sars-cov-2, to, coronavirus"
3643,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.166666667,"the, of, coronavirus, is, to, animal, be"
3644,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.166666667,"a, to, the, is, spillover"
3645,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.166666667,"is, sars-cov-2, the, and, animal"
3646,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.166666667,"of, the, sars-cov-2, is, a"
3647,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.166666667,"the, of, sars-cov-2, a, and"
3648,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.166666667,"an, of, to, sars-cov-2, and, the"
3649,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.166666667,"is, the, to, sars-cov-2, be"
3650,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.166666667,"is, a, of, sars-cov-2, the, human-to-human"
3651,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.166666667,"sars-cov-2, to, and, a, the, of"
3652,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.166666667,"is, the, coronavirus, to, be, of"
3653,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.166666667,"the, sources, of, are, bats, and"
3654,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.166666667,"has, been, that, the, of, are"
3655,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.166666667,"of, the, bats, natural"
3656,"civet cats and raccoon dogs  

are the intermediate hosts","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.166666667,"and, are, the"
3657,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.166666667,"t, was, the, is, identical, to, ratg13,"
3658,"natural selection in humans  

following zoonotic transfer",zoonotic origins of SARS-CoV-2 by natural evolution,0.166666667,"natural, zoonotic"
3659,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.166666667,"a, from, to, the, is"
3660,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.166666667,"the, is, to, isolated, from"
3661,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.166666667,"the, origin, sars-cov-2, a, from"
3662,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.166666667,"isolated, from, is, with, sars-cov-2, the, sequence"
3663,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.166666667,"the, sars-cov-2, is, with, to"
3664,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.166666667,"the, of, to, cross, barrier, species, and"
3665,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.166666667,"the, emerged, in, china"
3666,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.166666667,"analysis, that, sars-cov-2, is, bat, the"
3667,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.166666667,"analysis, shows, that, sars-cov-2, the, of"
3668,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.166666667,"the, shares, to, identity, with"
3669,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.166666667,"the, viral, reservoirs, are, of, bats"
3670,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.166666667,"that, bats, are, the, for"
3671,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.166666667,"that, natural, the, for, of"
3672,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","civet cats and raccoon dogs  

are the intermediate hosts",0.166666667,"are, and, the"
3673,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","civet cats and raccoon dogs  

are the intermediate hosts",0.166666667,"are, the, hosts, intermediate"
3674,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.166666667,"to, a, that, from, and, was, transmitted, humans,, the"
3675,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.166666667,"bats, and, are, the, sources, of"
3676,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.166666667,"sars-cov-2, to, are, bats, the"
3677,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.166666667,"the, sars-cov-2, to, be"
3678,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","with the first case being linked to  

a seafood market",0.166666667,"to, the, with, a"
3679,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","with the first case being linked to  

a seafood market",0.166666667,"the, a, seafood, market, to"
3680,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.166666667,"the, of, sars-cov-2, to, be, through, is, humans"
3681,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.166666667,"of, the, sars-cov-2, been, in, pangolins, from, is"
3682,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.166666667,"to, this, sars-cov-2, has, the, bats, be, of"
3683,COVID-19 is a potential zoonotic disease,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.166666667,"a, zoonotic, disease"
3684,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.166666667,"the, and, one, a, zoonotic, origin"
3685,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.166666667,"a, zoonotic, and, in, the, that"
3686,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.166666667,"are, likely, reservoir, sars-cov-2, as, to, a, bat"
3687,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.166666667,"a, that, sars-cov-2, emerged, from, spillover"
3688,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.166666667,"that, evidence, from, a, spillover, to"
3689,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.166666667,"that, sars-cov-2, emerged, of, a"
3690,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.166666667,"the, spillover, that, of"
3691,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.166666667,"into, the, that, sars-cov-2"
3692,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.166666667,"that, the, of, sars-cov-2, this, from, viruses"
3693,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.166666667,"this, a, separate, and, origin, of, lineage, at, the, in"
3694,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.166666667,"the, of, huanan, market, sars-cov-2, into, humans, at"
3695,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.166666667,"the, known, and, sars-cov-2, to, of"
3696,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.166666667,"that, the, are, to, huanan, market"
3697,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.166666667,"and, of, the, huanan, market, late"
3698,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.166666667,"that, the, of, to, and, huanan, market"
3699,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.166666667,"the, of, sars-cov-2, into, humans, at, huanan, market"
3700,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.166666667,"the, huanan, market, that, are, to"
3701,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.166666667,"a, lineage, the, huanan, market, in"
3702,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.166666667,"in, a, two, closely, related, are, to, the"
3703,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.166666667,"are, a, closely, related, to, in, more, the"
3704,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.166666667,"a, study, market, in, that, the, closely, related, to"
3705,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.166666667,"with, the, and, is, in, of"
3706,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.166666667,"a, origin, of, the, lineage, this, and, at, separate, in"
3707,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.166666667,"late, the, huanan, market, and, of"
3708,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.166666667,"in, a, the, lineage, huanan, market"
3709,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.166666667,"in, the, of, is, with, and, this, a"
3710,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.166666667,"the, was, from, sample, of, a, et"
3711,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.166666667,"sars-cov-2, with, other, a, that, emerged"
3712,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.166666667,"that, sars-cov-2, emerged, a, spillover, from"
3713,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.166666667,"that, the, covid-19, and, to, market,, of"
3714,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.166666667,"of, the, cases, that, market,, was"
3715,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.166666667,"a, in, the, that, to, of, sars-, cov-2"
3716,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.166666667,"sars-cov-2, their, is, a, that"
3717,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.166666667,"from, a, ,, to, in, the, that, it"
3718,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.166666667,"evidence, to, that, a, spillover, from"
3719,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.166666667,"that, is, to, originated, from"
3720,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.166666667,"a, strong, that, the, outbreak, is, of, and"
3721,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.166666667,"on, virus, and, bat, has, as"
3722,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.166666667,"the, virus, has, to, that, and, coronavirus"
3723,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.166666667,"the, virus, and, was, with, bat, coronavirus"
3724,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.166666667,"the, coronavirus, has, and, with, bat"
3725,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.166666667,"the, that, virus, to, a, and, has"
3726,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.166666667,"the, natural, host, of"
3727,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.166666667,"and, bat, very, high, to, the"
3728,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.166666667,"believed, the, be, of, to"
3729,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.166666667,"the, bats, in, of"
3730,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.166666667,"the, huanan, market, that, to, and, of"
3731,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.166666667,"of, cases, to, the, market, in, that, close"
3732,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.166666667,"that, the, of, cases, in, close, to, market"
3733,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.166666667,"in, the, of, virus, than, to, that, been, this"
3734,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.166666667,"the, covid-19, in, through, wuhan, december, of"
3735,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.166666667,"of, the, early, cases, in, by"
3736,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.166666667,"the, virus, coronavirus, that, has, and, to"
3737,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.166666667,"coronavirus, from, the, has, to, 99%"
3738,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.166666667,"the, and, of, virus, is, identical, to, that"
3739,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.166666667,"was, that, the, sars-cov-2, is, to, a"
3740,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.166666667,"the, a, was, humans,, that, transmitted, from, to, and"
3741,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.166666667,"a, from, the, pangolin, to, sars-cov-2"
3742,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.166666667,"a, was, that, the, sars-cov-2, and, to, is"
3743,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.166666667,"to, virus, and, was, available, the, sars-cov-2"
3744,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.166666667,"virus, genome, the, covid-19, to, bat, and, identity, that"
3745,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.166666667,"a, from, the, has, coronavirus, which, 99%, with"
3746,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.166666667,"that, the, of, genome, a, bat, coronavirus, covid-19"
3747,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","Bats have been reported as being the rich source of 

coronaviruses",0.166666667,"source, the, have, been"
3748,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Bats have been reported as being the rich source of 

coronaviruses",0.166666667,"the, of, been, reported"
3749,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Bats have been reported as being the rich source of 

coronaviruses",0.166666667,"have, of, bats, the, as"
3750,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.166666667,"the, has, to, 99%, coronavirus, from"
3751,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.166666667,"to, sars-cov-2, a, from, the, pangolin"
3752,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.166666667,"a, coronavirus, the, with, to"
3753,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.166666667,"have, shown, the, with, to"
3754,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.166666667,"sars-cov-2, to, have, the, with, pangolin"
3755,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.166666667,"the, sars-cov-2, to, a, with, pangolin"
3756,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.166666667,"sars-cov-2, the, and, infected, humans, from"
3757,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.166666667,"the, of, sars-cov-2, from, pangolins, and"
3758,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.166666667,"from, of, to, sars-cov-2, and, the, humans"
3759,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.166666667,"the, pangolins, of, similar, to, sars-cov-2, can"
3760,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.166666667,"the, from, identity, with"
3761,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.166666667,"bat, coronavirus, with, sars-cov-2"
3762,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.166666667,"sars-cov-2, genetic, and, a, virus, that"
3763,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.166666667,"the, of, pangolin-cov, to, sars-cov-2, that, virus"
3764,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.166666667,"the, of, and, to, is"
3765,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.166666667,"of, the, is, bat, possible, intermediate, hosts"
3766,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.166666667,"is, the, hosts, to, bat"
3767,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.166666667,"the, bat, pangolin, of"
3768,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.166666667,"the, and, bat, pangolin, of"
3769,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.166666667,"analysis, that, the, and, transmitted, to, humans, of"
3770,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.166666667,"of, the, have, that, which, was, by"
3771,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.166666667,"analysis, that, sars-cov-2, the, evolutionary, of, and, to"
3772,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.166666667,"the, bats, are, in, china"
3773,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.166666667,"the, virus, its, in, bats"
3774,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.166666667,"virus, transmitted, from, to, a"
3775,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.166666667,"was, from, are, to, and"
3776,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.166666667,"the, to, are, in, and"
3777,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.166666667,"of, covid-19, virus, is, to, the, and, was"
3778,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.166666667,"of, the, that, is, a"
3779,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.166666667,"the, that, were, to, in, likely, origin"
3780,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.166666667,"that, natural, in, and, the, virus"
3781,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.166666667,"the, virus, its, in"
3782,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.166666667,"virus, that, is, in"
3783,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.166666667,"is, that, the, similar, to"
3784,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.166666667,"the, to, in, and"
3785,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.166666667,"that, in, and, the, virus"
3786,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.166666667,"of, the, reported, in, market,, was"
3787,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.166666667,"with, the, and, sars-like, bat"
3788,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.166666667,"the, believed, to, be, of"
3789,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.166666667,"the, of, is, to, bats"
3790,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.166666667,"t, is, that, the, and"
3791,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.166666667,"is, the, virus, to, be"
3792,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.166666667,"the, of, to, that, virus, t"
3793,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.166666667,"of, the, that, is, virus"
3794,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.166666667,"and, that, of, the, virus, is"
3795,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.166666667,"of, that, the, virus, to, and"
3796,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.166666667,"is, the, to, be, sequence, of"
3797,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.166666667,"for, the, sars-cov, on, palm, civet, natural, reservoir, is, and"
3798,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.166666667,"on, the, and, natural, reservoir, is, palm, civet, for, sars-cov"
3799,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.166666667,"the, of, natural, host"
3800,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.166666667,"the, of, bats, natural, host, sars-like"
3801,"Bats have been reported as being the rich source of 

coronaviruses","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.166666667,"have, been, the, source"
3802,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.166666667,"the, analysis, that, sars-cov-2, is, bat"
3803,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.166666667,"is, the, related, to, sars-cov-2, be"
3804,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.166666667,"the, first, was, not, it, that, in"
3805,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.166666667,"as, a, of, the, in, was, it, used, infected, with"
3806,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.166666667,"a, was, seafood, market, in, wuhan, china, that, the, of, were"
3807,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.166666667,"sars-cov-2, to, of, coronavirus, the"
3808,"Bats have been reported as being the rich source of 

coronaviruses","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.166666667,"been, reported, the, of"
3809,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.166666667,"has, the, of, to, sars-cov-2"
3810,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.166666667,"the, of, sars-cov-2, coronavirus, has, been"
3811,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.166666667,"of, sars-cov-2, to"
3812,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.166666667,"close, to, the, of, sars-cov-2"
3813,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.166666667,"to, sars-cov-2, is, a, that, and, was, the"
3814,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.166666667,"is, to, be, of, animal, coronavirus, the"
3815,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.166666667,"in, and, to, humans, intermediate, hosts"
3816,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","Coronaviruses are naturally hosted and developmentally 

formed by bats.",0.166666667,"and, coronaviruses, are"
3817,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.166666667,"the, of, that, been, coronaviruses, it, from"
3818,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.166666667,"has, been, that, are, the, of"
3819,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.166666667,"from, are, coronaviruses, bat, the"
3820,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.166666667,"of, the, has, bat, human"
3821,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.166666667,"the, that, of, it, has, been"
3822,"bats are also important reservoir species for a great 

range of coronaviruses",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.166666667,"are, reservoir, of, coronaviruses"
3823,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.166666667,"the, between, sars-cov-2, and, have, to, of, genetic, is, bat"
3824,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.166666667,"the, virus, is, to, identical, that, of, and"
3825,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.166666667,"of, the, genome, sequence, virus, and, betacoronavirus, bat"
3826,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.166666667,"that, sars-cov-2, is, of, the, sarbecovirus"
3827,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.166666667,"that, pan-, golin, may"
3828,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.166666667,"studies, that, sars-cov-2, to"
3829,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.166666667,"the, as, are, from, viruses, in"
3830,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.166666667,"the, same, are, in, of"
3831,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.166666667,"its, the, virus, bats, in"
3832,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.166666667,"virus, from, to, human"
3833,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.166666667,"that, animal, zoonotic, is, a"
3834,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.166666667,"transmitted, to, an, animal"
3835,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.166666667,"is, to, a, spillover, the"
3836,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.166666667,"to, the, a, from, is"
3837,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.166666667,"the, from, a, animals, to, humans"
3838,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.166666667,"the, sars-cov-2, are, bats, to"
3839,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.166666667,"the, coronaviruses, are, from, bat"
3840,"Bats are natural hosts of many of the known  

coronaviruses","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.166666667,"bats, are, the, coronaviruses"
3841,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.166666667,"from, bats, to, humans, the"
3842,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.166666667,"to, the, isolated, from, is"
3843,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.166666667,"is, the, bats, of, to"
3844,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.166666667,"from, bats, to, the, of"
3845,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.166666667,"the, of, closely, related, to, is"
3846,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.166666667,"coronaviruses, related, to, in, bats, from"
3847,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.166666667,"population, and, to, an, in, the"
3848,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.166666667,"and, from, to, human, in, have, been, or"
3849,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.166666667,"is, that, sars-cov-2, and, animal"
3850,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.166666667,"that, sars-cov-2, is, a, virus."
3851,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.166666667,"natural, origin, sars-cov-2, a, and"
3852,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.166666667,"and, that, a, natural, origin, is"
3853,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.166666667,"sars-cov-2, is, animal, and, the"
3854,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.166666667,"infected, humans, from, and, the, sars-cov-2"
3855,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.166666667,"that, sars-cov-2, animal, and, is"
3856,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.166666667,"another, the, sars-cov-2, and, animal"
3857,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.166666667,"and, to, the, of, virus"
3858,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.166666667,"the, virus, was, coronavirus, with, bat, and"
3859,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.166666667,"the, and, betacoronavirus, of, genome, sequence, virus, bat"
3860,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.166666667,"and, the, covid-19, virus, identity, of, bat"
3861,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.166666667,"the, closest, relationship, with, of, virus, and"
3862,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.166666667,"the, of, to, from, bats"
3863,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.166666667,"the, virus, to, be, covid-19"
3864,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.166666667,"the, coronaviruses, to, that, are, and"
3865,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.166666667,"the, coronavirus, has, with, bat, and"
3866,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.166666667,"has, the, of, human, bat"
3867,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.166666667,"the, identity, of, with, and"
3868,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.166666667,"of, the, covid-19, virus, and, bat, identity"
3869,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.166666667,"the, that, virus, to, of, and, has"
3870,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.166666667,"the, natural, sars-cov-2, a, from, and"
3871,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.166666667,"the, sars-, cov-2, is, only, bat"
3872,"with the first case being linked to  

a seafood market","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.166666667,"the, to, a, seafood, market"
3873,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.166666667,"a, from, animals, to, humans, the"
3874,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.166666667,"that, in, and, wuhan, seafood, december, 2019"
3875,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.166666667,"the, of, sars-cov-2, a, between, from, and"
3876,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.166666667,"the, of, a, and, has, in, bat"
3877,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.166666667,"virus, isolated, from, in, with, sars-cov-2, the, sequence, of"
3878,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.166666667,"virus, is, that, in"
3879,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.166666667,"that, is, in, sars-cov-2"
3880,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.166666667,"that, sars-cov-2, is, a"
3881,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.166666667,"a, bat, from, in, sars-cov-2"
3882,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.166666667,"that, the, a, of, sars-cov, and"
3883,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.166666667,"the, sars-cov, and, to, bat, in, of, genome, sequence"
3884,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.166666667,"and, are, hosts, sars-cov-2"
3885,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.166666667,"are, the, of, sars-cov-2"
3886,"civet cats and raccoon dogs  

are the intermediate hosts","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.166666667,"are, the, intermediate, hosts"
3887,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.166666667,"to, the, of, may, be, most"
3888,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Bats are natural hosts of many of the known  

coronaviruses",0.166666667,"the, are, of, coronaviruses, many"
3889,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Bats are natural hosts of many of the known  

coronaviruses",0.166666667,"are, coronaviruses, bats, the"
3890,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.166666667,"this, hypothesis, the, of, which, that, was, to, but"
3891,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.166666667,"the, has, a, which, 99%, with, coronavirus, from"
3892,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.166666667,"that, the, of, is, to, a, it"
3893,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.166666667,"a, is, the, to, that, virus, and"
3894,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.166666667,"it, has, been, that, the, of"
3895,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.166666667,"a, the, to, that, in, was"
3896,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.166666667,"in, sars-, cov-2, the, of, that, a, to"
3897,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.166666667,"a, coronavirus, the, to, with"
3898,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.166666667,"in, the, of, that, was, to, similar"
3899,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.166666667,"the, coronavirus, was, to, a"
3900,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.166666667,"the, of, sars-, cov-2, to, that"
3901,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.166666667,"in, a, the, of, with"
3902,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.166666667,"in, the, of, a, was"
3903,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.166666667,"the, that, with, at, of, to"
3904,"Coronaviruses are naturally hosted and developmentally 

formed by bats.","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.166666667,"coronaviruses, are, and"
3905,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.166666667,"and, closely, related, to"
3906,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.166666667,"of, the, reported, cases, that, market,"
3907,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.166666667,"sars-cov-2, is, a, of, the"
3908,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.166666667,"is, that, the, of, a"
3909,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.166666667,"that, sars-cov-2, a, is, virus."
3910,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.166666667,"the, hypothesis, scientific, that, a, of"
3911,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.166666667,"a, that, the, is, of"
3912,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.166666667,"was, the, of, sars-cov-2, to, cov"
3913,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.166666667,"the, of, to, and, cov, bats"
3914,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.166666667,"the, of, to, sars-cov-2, was, bats"
3915,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.166666667,"of, a, the, was, et, from, sample"
3916,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.166666667,"that, the, of, spillover"
3917,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.166666667,"of, scientific, the, hypothesis, that, a"
3918,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.166666667,"the, for, viruses, in, of"
3919,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.166666667,"the, for, viruses, of"
3920,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.166666667,"of, viruses, in, natural, the"
3921,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.166666667,"sars-cov-2, a, of, and, the"
3922,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.166666667,"the, a, from, sars-cov-2, origin"
3923,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.166666667,"pangolins, from, and, the, of, sars-cov-2"
3924,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.166666667,"sars-cov-2, a, natural, origin, and"
3925,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.166666667,"the, sars-cov-2, natural, and, from, a"
3926,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.166666667,"a, between, sars-cov-2, and, the, of, from"
3927,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.166666667,"the, as, of, sars-cov-2, malayan, and"
3928,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.166666667,"the, of, which, that, but, was, to, this, hypothesis"
3929,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.166666667,"the, of, sars-cov-2, to, closely, related, virus, in"
3930,evidence suggests bats as its origin,"this one jumped from bats origin  

into humans",0.166666667,"bats, origin"
3931,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.166666667,"a, coronavirus, the, was, to"
3932,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.166666667,"are, most, all, in, including"
3933,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.166666667,"most, coronavirus, in, are"
3934,"bats are also important reservoir species for a great 

range of coronaviruses",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.166666667,"bats, are, a, of, coronaviruses"
3935,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.166666667,"has, a, and, the, of, bat, in"
3936,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.166666667,"the, and, sars-cov-2, to, in, of"
3937,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.166666667,"the, of, in, viruses, for"
3938,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.166666667,"and, of, sars-cov-2, in, the, for, viruses, to"
3939,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.166666667,"bats, the, natural, host, of, sars-like"
3940,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.166666667,"in, the, pangolins, were, intermediate"
3941,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.166666667,"in, a, the, possible, with"
3942,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.166666667,"sars-cov-2, a, it, in, intermediate, host"
3943,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.166666667,"to, be, the, most, of, may"
3944,"expended to make the simple point 

that COVID-19 had a natural origin.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.166666667,"to, the, that, covid-19, had"
3945,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.166666667,"to, available, sars-cov-2, virus, and, was, the"
3946,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.166666667,"the, sars-cov-2, genome, was, to"
3947,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.166666667,"that, sars-cov-2, the, into"
3948,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.166666667,"sars-cov-2, that, is, in"
3949,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.166666667,"is, that, the, sars-cov-2, to"
3950,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.166666667,"the, to, in, sars-cov-2"
3951,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.166666667,"virus, is, more, than, to, sars-cov-2, in"
3952,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.166666667,"sars-cov-2, with, within, and, is, a, virus, that"
3953,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.166666667,"with, the, and, sars-cov-2, is, to, in, of"
3954,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.166666667,"this, is, with, a, and, of, the, in"
3955,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.166666667,"this, of, to, the, than, in, that, been, virus"
3956,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.166666667,"a, few, to, in, more, with, sars-cov-2, than, the, and"
3957,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.166666667,"sars-cov-2, is, a, virus, that, with, to, the, for"
3958,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.166666667,"sars-cov-2, is, a, that, found, humans, with, to, the, over"
3959,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.166666667,"the, identity, of, sars-cov-2, with, and"
3960,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.166666667,"research, that, sars-cov-2, with, genome, bat"
3961,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.166666667,"that, the, sars-cov-2, is, to"
3962,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.166666667,"is, the, to, that, discovered"
3963,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.166666667,"the, discovered, to, that, sars-cov-2"
3964,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.166666667,"that, the, is, sars-cov-2"
3965,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.166666667,"the, shares, identity, with, to"
3966,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.166666667,"the, of, that, animal, is, zoonotic, origin"
3967,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.166666667,"that, is, animal, a, zoonotic"
3968,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.166666667,"has, a, origin, animal, host, zoonotic"
3969,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.166666667,"the, phylogenetic, analysis, that, sars-, and"
3970,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.166666667,"analysis, of, that, is, the, and"
3971,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.166666667,"ratg13,, the, of, is, sars-, cov-2"
3972,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.166666667,"the, of, sars-cov-2, has, to"
3973,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","bats are also important reservoir species for a great 

range of coronaviruses",0.166666667,"are, reservoir, of, a"
3974,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","bats are also important reservoir species for a great 

range of coronaviruses",0.166666667,"of, coronaviruses, are, reservoir"
3975,Coronaviruses account for over 30% of the world’s viruses.,"bats are also important reservoir species for a great 

range of coronaviruses",0.166666667,"coronaviruses, for, of"
3976,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.166666667,"sars-cov-2, to, of, an, and, the"
3977,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.166666667,"to, humans, from, and, the, of, sars-cov-2"
3978,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.166666667,"the, bats, species, to, of, sars-cov-2, and"
3979,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.166666667,"were, to, sars-cov-2, in, bats, and, from"
3980,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.166666667,"the, in, bats, and, to, humans, of"
3981,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.166666667,"an, species, bats, and, humans, in, the"
3982,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.166666667,"the, furin, cleavage, amino, acid, insertion, sars-cov-2"
3983,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.166666667,"cross, the, species, barrier, to, of, and"
3984,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.166666667,"the, sars-cov-2, to, humans, through, of, is, be"
3985,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.166666667,"the, as, very, to, a"
3986,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.166666667,"sars-cov-2, to, animal, and, the"
3987,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.166666667,"of, the, early, in, that, was"
3988,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.166666667,"coronavirus, bat, with, sars-cov-2"
3989,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.166666667,"bat, coronavirus, to, similarity, banal, sars-cov-2"
3990,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.166666667,"banal, series, to, sars-cov-2, similarity"
3991,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.166666667,"sars-cov-2, the, of, systems, that, been, to, coronaviruses, it, sequences, from"
3992,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.166666667,"in, the, of, sars-cov-2, closely, related, to, virus"
3993,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.166666667,"viral, of, the, bats, are, reservoirs"
3994,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.166666667,"bats, are, the, more, likely, of"
3995,Coronaviruses account for over 30% of the world’s viruses.,"Bats are the second  

largest order of mammals, with over 1,230 species.",0.166666667,"over, of, the"
3996,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Bats are the second  

largest order of mammals, with over 1,230 species.",0.166666667,"the, are, with, species."
3997,"bats are also important reservoir species for a great 

range of coronaviruses",Coronaviruses account for over 30% of the world’s viruses.,0.166666667,"for, of, coronaviruses"
3998,"Bats are the second  

largest order of mammals, with over 1,230 species.",Coronaviruses account for over 30% of the world’s viruses.,0.166666667,"the, of, over"
3999,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.166666667,"coronaviruses, of, among, including"
4000,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.166666667,"the, of, viruses, for"
4001,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.166666667,"of, viruses, reservoirs, and, the"
4002,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.166666667,"bats, the, for, of, and"
4003,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.166666667,"to, the, of, sars-cov-2, bats, as, intermediate"
4004,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.166666667,"the, of, sars-cov-2, as, malayan, and"
4005,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.166666667,"species, of, bats, to, sars-cov-2, and, the"
4006,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.166666667,"coronaviruses, are, to, the, that, and"
4007,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.166666667,"most, are, in, including, all"
4008,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.166666667,"the, discovered, that, to, sars-cov-2"
4009,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.166666667,"were, to, and, in, china"
4010,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.166666667,"the, to, in, china"
4011,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.166666667,"the, population, an, in, to, and"
4012,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.166666667,"bat, coronavirus, banal, similarity, to, sars-cov-2"
4013,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.166666667,"with, the, and, sars-cov-2, to, in, whole, genome"
4014,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.166666667,"in, a, related, the, two, are, closely, to"
4015,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.166666667,"banal, series, similarity, to, sars-cov-2"
4016,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.166666667,"the, of, is, to, sars-, cov-2"
4017,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.166666667,"the, shown, to, have, with"
4018,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.166666667,"of, the, banal, series, spike"
4019,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.166666667,"banal, series, the, of, spike"
4020,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.166666667,"the, junction, of, cleavage, site, a"
4021,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.166666667,"the, insertion, sars-cov-2, furin, amino, acid, cleavage"
4022,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.166666667,"in, was, first, and"
4023,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.166666667,"first, was, in, as"
4024,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.166666667,"sars-cov-2, is, to, be, the"
4025,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.166666667,"is, the, virus, be, to"
4026,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.166666667,"sars-cov-2, is, related, to, be, the"
4027,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.166666667,"to, be, the, covid-19, virus"
4028,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.166666667,"in, a, related, the, are, more, closely, to"
4029,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.166666667,"in, the, more, than, to, sars-cov-2, with, and, a, few"
4030,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.166666667,"sars-cov-2, is, that, humans, through, infected, the, over"
4031,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.166666667,"as, a, of, the, palm, civets, and, were, in, to, sars, with, evidence, for, found, that, taken, from, collected, dogs, intermediate, host"
4032,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.166666667,"for, the, of, dogs, and, civets, were, intermediate, host, that, collected, from, palm, a, found, in, sars, taken, evidence, with, as, to"
4033,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.166666667,"the, origin, and, a, zoonotic, one"
4034,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.166666667,"the, of, a, between, and, market"
4035,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.166666667,"the, and, a, zoonotic, that, in"
4036,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.166666667,"the, virus, for, is, to, that, sars-cov-2, with, a"
4037,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.166666667,"that, to, humans, is, a, found, with, sars-cov-2, over, the"
4038,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.166666667,"over, humans, through, is, that, the, sars-cov-2, infected"
4039,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","expended to make the simple point 

that COVID-19 had a natural origin.",0.166666667,"a, the, to, that, had"
4040,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","expended to make the simple point 

that COVID-19 had a natural origin.",0.166666667,"that, the, had, to, covid-19"
4041,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.166666667,"in, related, to, coronaviruses, from, bats"
4042,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.166666667,"in, from, bats, were, to, sars-cov-2, and"
4043,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.166666667,"to, and, that, related, in, including, asian, countries"
4044,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.166666667,"the, natural, of, in, viruses"
4045,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.166666667,"the, reservoirs, viruses, of, and"
4046,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.166666667,"animal, host, has, zoonotic, origin, a"
4047,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.166666667,"sars-cov-2, is, a, that, emerged"
4048,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.166666667,"that, sars-cov-2, emerged, a, of"
4049,zoonotic origins of SARS-CoV-2 by natural evolution,"natural selection in humans  

following zoonotic transfer",0.166666667,"zoonotic, natural"
4050,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.166666667,"the, that, to, of, sars-, cov-2"
4051,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.166666667,"to, that, the, of, sars-, cov-2, is"
4052,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.166666667,",, the, that, in, a, it, to, from"
4053,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.166666667,"of, the, a, cleavage, site, junction"
4054,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.166666667,"sars-cov-2, is, a, of, the, human-to-human"
4055,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.166666667,"pangolins, similar, to, can, the, of, sars-cov-2"
4056,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.166666667,"t, that, the, virus, of, to"
4057,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.166666667,"sars-cov-, a, recombination, of, with, and, pangolins, the, sars-cov-2"
4058,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.166666667,"we, and, that, in, the, of, sars-cov-2"
4059,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.166666667,"have, been, human, from, in, or, to, and"
4060,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.166666667,"the, covid-19, a, genome, of, that, coronavirus, bat"
4061,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.166666667,"the, evidence, this, that, a, virus, in, animal"
4062,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.166666667,"and, to, bats, cov, the, of"
4063,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.166666667,"phylogenetic, analysis, the, sars-, that, and"
4064,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",The COVID-19 most likely developed from bat origin coronaviruses,0.166666667,"from, coronaviruses, bat, the"
4065,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.166666667,"the, is, of, possible, intermediate, hosts, bat"
4066,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.166666667,"to, the, of, bats, intermediate, hosts, humans"
4067,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.166666667,"of, the, covid-19, to, market,, and, that"
4068,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.166666667,"of, covid-19, in, december, the, wuhan, through"
4069,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.166666667,"the, analysis, of, and, that, transmitted, to, humans"
4070,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.166666667,"to, in, humans, and, intermediate, hosts"
4071,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.166666667,"that, and, in, seafood, wuhan, december, 2019"
4072,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.166666667,"in, of, bats, to, and, the, humans"
4073,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.166666667,"of, analysis, that, the, virus, to, and"
4074,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.166666667,"of, coronaviruses, among, including"
4075,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.166666667,"that, to, be, originated"
4076,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",Bats are hosts of many coronaviruses,0.166666667,"coronaviruses, are, of"
4077,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",Bats are hosts of many coronaviruses,0.166666667,"of, bats, are"
4078,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.166666667,"transmitted, an, animal, to"
4079,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.166666667,"to, is, be, the"
4080,Genetic evidence suggesting otherwise is yet to be presented.,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.166666667,"is, to, be"
4081,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.166666667,"of, the, cases, market,, that, was"
4082,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.166666667,"of, cases, in, the, by, early"
4083,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.166666667,"the, of, have, that, which, was, by"
4084,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.166666667,"market,, in, the, was, reported, of"
4085,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.166666667,"of, reported, cases, the, market,, that"
4086,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.166666667,"the, of, in, early, that, was"
4087,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.166666667,"the, of, that, to, it, is, covid-19"
4088,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.166666667,"to, is, of, the, covid-19, virus, and, was"
4089,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.166666667,"analysis, of, the, that, and, is"
4090,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.166666667,"that, of, virus, similar, to, and, the, for"
4091,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.166666667,"analysis, revealed, the, for, and"
4092,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.166666667,"that, and, the, virus, for, of"
4093,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.166666667,"the, of, people, that, to, in, it, this"
4094,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.166666667,"that, in, the, it, was, not, first"
4095,"Bats have been reported as being the rich source of 

coronaviruses","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.166666667,"bats, have, as, the, of"
4096,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.166666667,"that, is, of, the"
4097,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.166666667,"that, is, the, of"
4098,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.166666667,"the, sars-, cov-2, bat, is, only"
4099,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.166666667,"bats, and, to, be, the"
4100,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.166666667,"from, humans, to, bats, the"
4101,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.166666667,"to, the, scenario, and, is, be"
4102,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.166666667,"in, an, species, bats, and, the, humans"
4103,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.166666667,"a, in, the, was, of"
4104,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.166666667,"was, first, in, and"
4105,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.166666667,"the, between, and, market, of, a"
4106,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.166666667,"the, sars-cov-2, been, from, pangolins, in, of, is"
4107,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.166666667,"the, sequence, with, isolated, from, sars-cov-2, is"
4108,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.166666667,"sequence, sars-cov-2, with, the, of, virus, isolated, from, in"
4109,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.166666667,"that, a, the, of, outbreak, and, is, strong"
4110,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.166666667,"and, that, a, of, the, is"
4111,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.166666667,"suggesting, sars-cov-2, might, a, and, cov"
4112,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.166666667,"is, that, the, virus, of"
4113,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.166666667,"analysis, that, sars-cov-2, the, of, virus"
4114,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.166666667,"the, virus, of, and, to"
4115,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.166666667,"the, of, scientific, at, that, a, virus, has, been"
4116,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.166666667,"most, are, in, coronavirus"
4117,"Bats are the second  

largest order of mammals, with over 1,230 species.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.166666667,"are, the, with, species."
4118,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.166666667,"a, intermediate, host, sars-cov-2, it, in"
4119,The FCS of SARS-CoV-2 was not bioengineered—full stop.,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.166666667,"the, of, sars-cov-2, not"
4120,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.166666667,"sars-cov-2, the, of"
4121,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.166666667,"of, sars-cov-2, not, the"
4122,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.166666667,"the, was, as, animal, for"
4123,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.166666667,"the, sars-cov-2, be, to"
4124,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.166666667,"to, genome, was, the, sars-cov-2"
4125,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.166666667,"sars-cov-2, be, the, cov"
4126,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.166666667,"is, that, the, virus, and, of"
4127,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.166666667,"that, a, natural, origin, and, is"
4128,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.166666667,"a, that, the, is, of, and"
4129,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.166666667,"was, to, ratg13, and, that, sars-cov-2"
4130,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.166666667,"are, and, was, from, to"
4131,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.166666667,"that, and, are, sars-cov-2"
4132,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.166666667,"the, of, sars-cov-2, with, to"
4133,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.166666667,"to, is, and, be, the, scenario"
4134,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.166666667,"evidence, to, that, sars-, cov-2, the, of, and, origin"
4135,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.166666667,"that, bats, the, hosts, for, sars-cov-2"
4136,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.166666667,"sars-cov-2, are, hosts, and"
4137,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.166666667,"sars-cov-2, that, are, and"
4138,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.166666667,"that, and, pangolins, are, hosts, for, sars-cov-2"
4139,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.166666667,"virus, more, than, whole, genome"
4140,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.166666667,"that, bats, are, the, hosts, for"
4141,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.166666667,"in, a, related, study, that, the, closely, to, market"
4142,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.166666667,"was, that, the, wuhan, in, china, seafood, market, were, a, of"
4143,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.166666667,"that, sars-cov-2, to, bat, as, the"
4144,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.166666667,"the, that, bats, are, for"
4145,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.166666667,"sars-cov-2, reservoir, to, a, are, as, likely, bat"
4146,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.166666667,"the, is, to, hosts, bat"
4147,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.166666667,"the, a, as, to, very"
4148,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.166666667,"analysis, that, the, virus, and, to, of"
4149,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.166666667,"sars-cov-2, genome, sequences, a, the, origin, of"
4150,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.166666667,"sars-cov-2, to, the, for, viruses, in, and, of"
4151,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.166666667,"the, of, sars-cov-, pangolins, with, a, and, sars-cov-2, recombination"
4152,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.166666667,"of, virus, that, similar, to, the, and, for"
4153,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.166666667,"ratg13, is, bat, to, than"
4154,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.166666667,"that, the, of, sars-cov-2, is"
4155,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.166666667,"the, sars-cov-2, of, sarbecovirus, is, that"
4156,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.166666667,"is, that, the, of, sars-cov-2"
4157,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.166666667,"is, that, of, the"
4158,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.166666667,"the, of, sars-cov-2, is"
4159,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.166666667,"viruses, are, into, 2, clusters, and, while, with, bat, cov, pangolin, cluster, the, sars"
4160,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.166666667,"viruses, that, the, of, sars-cov-2, from, this"
4161,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.166666667,"the, of, sars-cov-2, has, been, coronavirus"
4162,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.166666667,"this, the, that, bats, more, likely, sars-cov-2"
4163,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.166666667,"in, this, that, the, between, and, bat"
4164,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.166666667,"in, the, is, to, sars-cov-2, that, pangolin, cov"
4165,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same",0.166666667,"the, and, bat, cov, sars, same"
4166,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.166666667,"while, the, bat, cov, and, are, into, clusters, cluster, 2, with, viruses, sars, pangolin"
4167,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.166666667,"the, pangolin, to, have, with, sars-cov-2"
4168,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.166666667,"the, pangolin, of, bat"
4169,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.166666667,"that, the, sars-cov-2, this, more, likely, bats"
4170,"�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.166666667,"sars, cov, bat, and, the, same"
4171,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.166666667,"sars-cov-2, bats, of, more, than"
4172,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.166666667,"the, of, that, this, likely, origin"
4173,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.166666667,"the, of, sars-cov-2, are"
4174,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.166666667,"sars-cov-2, are, the, of"
4175,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.166666667,"the, likely, are, more, of, bats"
4176,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.166666667,"the, sars-cov-2, this, origin, of"
4177,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.166666667,"the, pangolin, of, bat, and"
4178,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.166666667,"this, the, origin, of, sars-cov-2"
4179,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.166666667,"bat, cov, and, the, same, sars-cov-2, ratg13, guangdong"
4180,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.166666667,"the, sars-cov-2, and, bat, cov, ratg13, guangdong, same"
4181,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.166666667,"to, that, the, of, sars-, cov-2, origin, and, evidence"
4182,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.166666667,"the, and, bat, covs, in, of, genome"
4183,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.166666667,"a, origin, of, sars-cov-2, genome, sequences, the"
4184,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.166666667,"a, the, pangolin, to, with, sars-cov-2"
4185,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.166666667,"to, the, with, sars-cov-2, is"
4186,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.166666667,"to, and, with, the, of, sars-cov-2"
4187,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.166666667,"is, the, and, of, to"
4188,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.166666667,"sars-cov-2, the, with, of, and, to"
4189,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.166666667,"of, the, and, identity, with"
4190,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.166666667,"the, of, and, identity, with, sars-cov-2"
4191,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.166666667,"sars-cov-2, is, of, the"
4192,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.166666667,"the, sars-cov-2, with, bat-sl-cov-2, of, pangolin-cov"
4193,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.166666667,"the, of, bat-sl-cov-2, showed, identity, sars-cov-2"
4194,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.166666667,"the, analysis, shows, that, sars-cov-2, of"
4195,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.166666667,"the, analysis, of, and, that, sars-cov-2, to, evolutionary"
4196,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.166666667,"analysis, of, the, that, sars-cov-2, virus"
4197,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.166666667,"analysis, revealed, the, and, for"
4198,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.166666667,"the, in, and, that, for, of"
4199,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.166666667,"we, sars-cov-2, the, and, in, that, of"
4200,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.166666667,"a, of, the, that, sars-cov, and"
4201,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.166666667,"the, that, bats, are, hosts, for"
4202,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.166666667,"are, and, the, to, in"
4203,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.166666667,"the, to, and, in"
4204,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.166666667,"the, in, to, sars-cov-2"
4205,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.166666667,"of, the, that, natural, for"
4206,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.166666667,"the, natural, that, virus, in, and"
4207,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.166666667,"the, virus, and, that, in"
4208,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.166666667,"of, virus, that, the, and, for"
4209,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.166666667,"of, the, virus, and, closest, relationship, with"
4210,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.166666667,"the, with, that, to, of, at"
4211,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.166666667,"the, of, sars-cov-2, with, bat-sl-cov-2, pangolin-cov"
4212,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.166666667,"the, of, at, that, sars-cov-2, virus, has"
4213,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.166666667,"this, and, bat, the, between, that, in"
4214,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.166666667,"sars-cov-2, was, to, bats, the, of"
4215,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.166666667,"the, of, sars-cov-2, showed, identity, bat-sl-cov-2"
4216,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.166666667,"virus, is, identical, to, sars-cov-2, in"
4217,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.166666667,"of, to, that, sars-cov-2, the, pangolin-cov, virus"
4218,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.166666667,"is, sars-cov-2, cov, pangolin, to, the, that, in"
4219,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.166666667,"the, host, sars-cov-2, intermediate"
4220,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.166666667,"the, sars-cov-2, has, to, bats, of, this, be"
4221,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.166666667,"was, first, in, as"
4222,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.166666667,"animal, as, was, the, for"
4223,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.166666667,"such, is, to, sars-cov-2"
4224,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.166666667,"that, is, originated, from, to"
4225,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.166666667,"studies, that, to, sars-cov-2"
4226,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.166666667,"sars-cov-2, the, and, another, animal"
4227,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.166666667,"the, intermediate, host, sars-cov-2"
4228,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.166666667,"cov, suggesting, and, sars-cov-2, might, a"
4229,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.166666667,"the, sars-cov-2, be, cov"
4230,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.166666667,"the, that, a, virus, in, animal, this, evidence"
4231,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.166666667,"a, of, the, at, has, been, that, scientific, virus"
4232,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.166666667,"the, that, sars-cov-2, has, at, of, virus"
4233,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.166666667,"sars-cov-2, from, a, in, bat"
4234,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.166666667,"was, that, the, of, sars-cov-2, to"
4235,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.166666667,"that, the, of, similar, to, sars-cov-2"
4236,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.166666667,"the, of, to, that, sars-cov-2, was"
4237,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.166666667,"is, to, be, of, coronavirus, the"
4238,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.166666667,"is, the, be, of, sequence, to"
4239,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.166666667,"bat, ratg13, is, to, than"
4240,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.166666667,"that, related, to, in, asian, countries, including, and"
4241,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.166666667,"of, the, sars-, cov-2, ratg13,, is"
4242,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.166666667,"the, of, to, is, sars-, cov-2"
4243,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.166666667,"the, and, sars-cov-2, to, bat, of"
4244,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.166666667,"the, to, bat, and, very, high"
4245,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.164285714,"from, the, samples,, wiv, team, for, to, a, sars-related, virus, this, bat, and, researchers, rsshc014, sars, in, 2013,, of, coronavirus, yunnan, at, discovery."
4246,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.164285714,"in, 2013,, a, team, of, wiv, researchers, to, sars-related, yunnan, discovery., the, from, for, samples,, coronavirus, this, bat, rsshc014, and, sars, at, virus"
4247,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.164179104,"two, viruses, of, the, sars-cov-2, lineage, in, from, their, origin, and"
4248,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.164179104,"that, the, similarity, of, sars-cov-2, and, sars-cov, as, et, al.,, 2020)"
4249,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.164179104,"that, the, of, as, sars-cov-2, et, al.,, 2020), and, similarity, sars-cov"
4250,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.164179104,"the, by, a, huanan, seafood, and, of, wuhan, december, 18, with"
4251,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.164179104,"by, a, of, the, wuhan, december, 18, and, with, huanan, seafood"
4252,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.164179104,"on, the, of, binding, spike, protein, that, this, natural, a, manipulation."
4253,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.164179104,"origin, of, the, from, lineage, sars-cov-2, and, two, in, viruses, their"
4254,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.164179104,"the, binding, of, spike, protein, natural, on, a, that, this, manipulation."
4255,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.164179104,"with, the, fig., that, sars-cov-2, is, bat, cov, ratg13, are, cluster"
4256,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.164179104,"fig., bat, cov, ratg13, is, the, cluster, with, sars-cov-2, that, are"
4257,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.163934426,"evidence, to, sars-cov-2, from, of, in, bats, the, has, been"
4258,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.163934426,"the, sars-cov-2, has, been, to, from, bats, evidence, in, of"
4259,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.163636364,"is, the, bat, to, be, amino, acid, in, of"
4260,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.163636364,"is, that, the, virus, and, bats, be, of, to"
4261,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.163636364,"the, also, for, to, a, virus, that, with, ace2, as, entry, receptor, and, in, of, coronavirus, use, an"
4262,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.163636364,"the, that, of, cases, with, huanan, market, and, in"
4263,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.163636364,"bats, the, of, is, virus, and, be, that, to"
4264,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.163636364,"the, was, have, it, that, in, with, of, animals"
4265,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.163636364,"et, that, have, of, virus, to, and, the, sars-cov-2"
4266,"Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.163636364,"based, on, the, of, that, were, in, suggested, likely"
4267,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.163636364,"and, also, of, between, sars-cov-2, is, the, for, to"
4268,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.163636364,"at, the, s1/s2, cleavage, site, a, furin, to, sars-cov-2,"
4269,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.163636364,"the, coronaviruses, with, a, and, more, sars-cov-2, these, recombination"
4270,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.163636364,"to, a, palm, as, civets, from, in, for, the, virus, or, collected, earliest, sars, were, of, and, species"
4271,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.163636364,"also, a, for, coronavirus, as, the, of, virus, and, in, with, that, to, use, ace2, receptor, an, entry"
4272,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.163636364,"for, the, of, and, civets, were, species, virus, collected, from, palm, a, in, earliest, sars, or, as, to"
4273,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.163636364,"that, the, of, cases, in, with, and, huanan, market"
4274,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.163636364,"a, coronaviruses, recombination, more, with, sars-cov-2, these, the, and"
4275,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.163636364,"based, on, in, the, of, suggested, that, were, likely"
4276,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.163636364,"it, was, that, the, with, in, have, animals, of"
4277,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.163636364,"the, of, sars-cov-2, to, is, also, for, and, between"
4278,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.163636364,"et, al., (2020), have, of, pangolin, similar, to, and"
4279,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.163636364,"have, the, sars-cov-2, and, of, et, virus, to, that"
4280,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.163636364,"et, al., (2020), of, pangolin, and, have, similar, to"
4281,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.163636364,"to, sars-cov-2,, a, furin, cleavage, site, at, the, s1/s2"
4282,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.163636364,"the, amino, acid, to, be, of, is, in, bat"
4283,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.163265306,"sars-cov, and, bat, coronaviruses, sequences, in, similar, to"
4284,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.163265306,"the, a, genome, of, to, identity, that, bat"
4285,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.163265306,"sars-cov-2, and, bat, cov, ratg13, to, the, that"
4286,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.163265306,"the, that, of, known, are, huanan, market, and"
4287,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.163265306,"the, that, cases, are, huanan, market, lineage, in"
4288,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.163265306,"the, of, and, that, is, an, which, to"
4289,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.163265306,"the, and, that, sars-cov-2, is, was, transmitted, to"
4290,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.163265306,"that, the, virus, bats, and, to, from, a"
4291,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.163265306,"that, the, genome, of, to, a, bat, identity"
4292,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.163265306,"the, that, has, with, of, virus, and, to"
4293,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.163265306,"the, an, which, is, to, that, of, and"
4294,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.163265306,"to, sars-cov-2, is, that, and, was, transmitted, the"
4295,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.163265306,"to, a, virus, that, from, bats, and, the"
4296,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.163265306,"it, is, the, reservoir, for, as, a, bat"
4297,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.163265306,"bat, to, genetic, similarity, is, sars-cov-2, the, genome"
4298,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.163265306,"the, species, that, from, jumped, humans, infected, and"
4299,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.163265306,"a, bat, of, sars-cov-2, genome, the, in, china"
4300,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.163265306,"in, bat, coronaviruses, sequences, similar, to, sars-cov, and"
4301,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.163265306,"the, of, from, two, and, were, with, genome"
4302,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.163265306,"the, that, of, has, not, been, is, a"
4303,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.163265306,"with, the, of, were, genome, two, from, and"
4304,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.163265306,"the, of, is, not, that, has, been, a"
4305,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.163265306,"humans, through, it, is, the, be, and, sars-cov-2"
4306,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.163265306,"the, genetic, similarity, sars-cov-2, genome, is, to, bat"
4307,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.163265306,"at, which, was, in, the, with, genome, level"
4308,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.163265306,"to, that, sars-, cov-2, the, of, and, are"
4309,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.163265306,"the, sars-cov-2, be, through, it, is, humans, and"
4310,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.163265306,"the, and, huanan, seafood, market, of, a, to"
4311,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.163265306,"the, a, huanan, seafood, market, and, to, of"
4312,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.163265306,"the, huanan, market, that, are, known, and, of"
4313,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.163265306,"in, that, the, lineage, cases, are, huanan, market"
4314,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.163265306,"of, that, the, is, bat, as, hosts, for"
4315,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.163265306,"to, a, ratg13,, which, from, rhinolophus, affinis, in"
4316,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.163265306,"the, of, bat, is, that, as, hosts, for"
4317,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.163265306,"evidence, for, between, and, that, in, the, of"
4318,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.163265306,"that, jumped, the, species, and, infected, humans, from"
4319,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.163265306,"it, is, that, are, the, for, sars-cov-2, as"
4320,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.163265306,"a, for, the, as, reservoir, bat, is, it"
4321,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.163265306,"the, that, are, sars-cov-2, is, it, as, for"
4322,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.163265306,"genome, a, sars-cov-2, the, of, bat, in, china"
4323,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.163265306,"ratg13,, from, a, rhinolophus, affinis, to, in, which"
4324,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.163265306,"the, that, sars-cov-2, with, of, virus, and, to"
4325,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.163265306,"the, to, bat, cov, ratg13, and, that, sars-cov-2"
4326,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.163265306,"the, of, and, are, to, that, sars-, cov-2"
4327,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.163265306,"evidence, that, the, of, and, in, between, for"
4328,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.163265306,"the, virus, has, of, to, with, that, and"
4329,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.163265306,"that, of, virus, with, to, and, the, sars-cov-2"
4330,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.163265306,"was, in, with, which, at, the, genome, level"
4331,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.162790698,"other, sars-cov-2, are, to, pangolin, and, a"
4332,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.162790698,"the, virus, is, that, had, its, in"
4333,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.162790698,"viruses, are, to, bat, that, the, of"
4334,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.162790698,"of, that, the, to, many, bat, and"
4335,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.162790698,"the, and, sars-cov-2, to, bat, genome, sequence"
4336,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.162790698,"sars-cov-2, and, bat, ratg13, identity, to, the"
4337,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.162790698,"genome, the, to, bat, and, sequence, sars-cov-2"
4338,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.162790698,"96.2%, similarity, to, a, sequence, was, in"
4339,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.162790698,"is, that, the, wuhan, of, to, covid-19"
4340,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.162790698,"the, of, to, it, is, likely, that"
4341,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.162790698,"in, and, to, a, market, wuhan,, china"
4342,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.162790698,"and, shown, that, most, by, bats, of"
4343,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.162790698,"sars-, the, of, bats, and, may, hosts"
4344,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.162790698,"a, sequence, sars-cov-2, with, the, isolated, from"
4345,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.162790698,"a, sars-cov-2, to, with, coronavirus, origin, zoonotic"
4346,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.162790698,"that, the, sars-cov-2, and, to, is, sars-cov"
4347,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.162790698,"are, to, of, the, bats, and, transmitted"
4348,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.162790698,"of, phylogenetic, suggest, that, the, bat, and"
4349,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.162790698,"the, viruses, are, of, bat, that, to"
4350,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.162790698,"at, least, two, of, sars-cov-2, from, to"
4351,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.162790698,"the, mutations, that, a, to, two, from"
4352,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.162790698,"at, are, a, this, the, that, to"
4353,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.162790698,"the, of, at, this, that, sars-cov-2, a"
4354,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.162790698,"the, of, sars-cov-2, to, be, through, and"
4355,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.162790698,"at, least, two, to, of, sars-cov-2, from"
4356,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.162790698,"a, two, mutations, to, that, the, from"
4357,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.162790698,"covid-19, a, in, that, originated, from, animal"
4358,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.162790698,"we, that, sars-cov-2, is, naturally, of, the"
4359,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.162790698,"and, the, to, a, market, in, wuhan,"
4360,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.162790698,"of, that, the, virus, to, which, and"
4361,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.162790698,"a, that, the, was, to, and, sars-cov-2"
4362,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.162790698,"that, sars-cov-2, to, pangolin, and, a, the"
4363,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.162790698,"and, of, between, is, the, to, human"
4364,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.162790698,"of, the, analysis, that, sars-cov-2, is, to"
4365,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.162790698,"the, in, wuhan,, to, a, and, market"
4366,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.162790698,"to, have, started, at, the, market, in"
4367,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.162790698,"the, of, are, bats, and, transmitted, to"
4368,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.162790698,"is, that, had, the, virus, its, in"
4369,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.162790698,"in, the, virus, is, to, that, and"
4370,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.162790698,"from, animals, in, have, been, or, common"
4371,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.162790698,"the, sars-cov-2, that, sars-cov, and, is, to"
4372,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.162790698,"of, the, sequence, that, and, sars-cov-2, is"
4373,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.162790698,"shown, that, bats, and, of, most, by"
4374,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.162790698,"and, evidence, sars-cov-2, natural, origin, has, is"
4375,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.162790698,"from, with, genome, the, of, covid-19, virus"
4376,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.162790698,"genome, of, the, covid-19, virus, from, with"
4377,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.162790698,"the, analysis, of, that, sars-cov-2, is, to"
4378,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.162790698,"the, sequence, with, a, isolated, from, sars-cov-2"
4379,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.162790698,"the, of, with, nearly, a, and, sars-cov-2"
4380,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.162790698,"and, that, a, of, the, virus, is"
4381,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.162790698,"of, a, that, the, virus, to, and"
4382,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.162790698,"that, to, and, a, hypothesis, the, of"
4383,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.162790698,"the, was, a, at, to, of, with"
4384,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.162790698,"the, cases, huanan, seafood, of, suggesting, to"
4385,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.162790698,"have, the, started, in, to, at, market"
4386,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.162790698,"sars-cov-2, from, a, bat, to, in, an"
4387,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.162790698,"indicated, that, virus, found, in, of, sars-cov-2"
4388,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.162790698,"this, that, in, pangolin, the, virus, of"
4389,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.162790698,"the, of, that, to, wuhan, is, covid-19"
4390,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.162790698,"in, the, is, not, to, that, sars-cov-2"
4391,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.162790698,"the, virus, is, to, and, that, in"
4392,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.162790698,"the, that, is, not, in, to, sars-cov-2"
4393,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.162790698,"this, that, the, more, of, sars-cov-2, than"
4394,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.162790698,"in, from, of, were, sars-cov-2, and, the"
4395,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.162790698,"found, in, of, indicated, that, sars-cov-2, virus"
4396,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.162790698,"the, sars-cov-2, and, of, sequence, is, that"
4397,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.162790698,"the, of, from, and, were, in, sars-cov-2"
4398,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.162790698,"to, sars-cov-2, a, that, and, was, the"
4399,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.162790698,"through, the, to, be, sars-cov-2, and, of"
4400,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.162790698,"the, of, at, this, time, that, in"
4401,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.162790698,"the, are, most, in, china, and, southeast"
4402,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.162790698,"the, most, are, in, southeast, and, china"
4403,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.162790698,"the, that, all, sars-cov-2, to, bat, and"
4404,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.162790698,"in, 2017,, the, same, of, researchers, a, to, on, cave, by, found, “all, building, sars-related, similar, that, likely, sars, yunnan, reservoir"
4405,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.162790698,"a, the, with, was, to, of, at"
4406,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.162790698,"the, of, on, by, likely, reservoir, in, researchers, found, a, similar, to, sars, sars-related, cave, yunnan, 2017,, that, same, “all, building"
4407,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.162790698,"the, is, that, of, known, covid-19, cases, with, huanan, market, and, in, all, but"
4408,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.162790698,"of, cases, to, the, huanan, seafood, suggesting"
4409,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.162790698,"and, a, natural, origin, of, the, is"
4410,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.162790698,"a, are, at, to, that, the, this"
4411,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.162790698,"the, huanan, market, is, that, in, of, cases, and, with, but, all, known, covid-19"
4412,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.162790698,"virus, that, is, most, to, the, for"
4413,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.162790698,"the, of, that, to, it, is, likely"
4414,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.162790698,"the, that, virus, can, in, means, probably"
4415,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.162790698,"the, of, this, that, sars-cov-2, virus, in"
4416,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.162790698,"a, of, the, sars-cov-2, with, nearly, and"
4417,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.162790698,"from, or, animals, in, have, been, common"
4418,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.162790698,"the, that, bat, as, animal, origin, for"
4419,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.162790698,"analysis, that, the, of, virus, and, to"
4420,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.162790698,"is, virus, that, to, the, most, for"
4421,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.162790698,"sars-cov-2., is, and, bat, to, the, that"
4422,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.162790698,"the, in, that, means, can, probably, virus"
4423,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.162790698,"bats, to, humans, direct, contact, and, be"
4424,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.162790698,"direct, to, humans, be, contact, and, bats"
4425,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.162790698,"to, sars-cov-2, in, from, an, a, bat"
4426,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.162790698,"the, is, that, virus, a, of, and"
4427,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.162790698,"the, and, is, of, a, natural, origin"
4428,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.162790698,"evidence, sars-cov-2, has, natural, origin, and, is"
4429,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.162790698,"2, to, sars-cov-, and, therefore, could, be"
4430,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.162790698,"the, a, coronavirus, that, bat, and, to"
4431,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.162790698,"the, to, that, sars-cov-2, all, bat, and"
4432,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.162790698,"the, and, of, bat, that, many, to"
4433,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.162790698,"phylogenetic, and, suggest, that, the, bat, of"
4434,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.162790698,"the, virus, which, to, that, of, and"
4435,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.162790698,"the, that, virus, to, a, of, and"
4436,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.162790698,"a, to, in, 96.2%, sequence, similarity, was"
4437,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.162790698,"the, is, to, of, between, and, human"
4438,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.162790698,"that, naturally, the, of, sars-cov-2, is, we"
4439,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.162790698,"with, the, and, of, sarbecovirus, bat, cov, pangolin, are, sars-, cov-2, as, join, cluster"
4440,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.162790698,"sars-cov-, 2, to, and, therefore, could, be"
4441,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.162790698,"provide, evidence, for, and, that, in, the"
4442,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.162790698,"that, is, to, the, bat, and, sars-cov-2."
4443,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same",0.162790698,"bat, sars, cov, and, zc45, the, same"
4444,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.162790698,"of, the, bat, cov, and, are, sarbecovirus, cluster, sars-, cov-2, join, with, as, pangolin"
4445,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.162790698,"the, of, more, than, that, sars-cov-2, this"
4446,"�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.162790698,"sars, cov, bat, zc45, and, the, same"
4447,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.162790698,"bats, may, the, hosts, of, sars-, and"
4448,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.162790698,"and, sars-cov-2, are, to, pangolin, a, other"
4449,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.162790698,"to, sars-cov-2, a, that, and, the, pangolin"
4450,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.162790698,"the, hypothesis, that, to, a, of, and"
4451,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.162790698,"the, in, and, provide, evidence, that, for"
4452,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.162790698,"this, in, the, of, that, pangolin, virus"
4453,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.162790698,"this, that, bat-, the, be, of, recombination"
4454,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.162790698,"this, be, that, the, recombination, bat-, of"
4455,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.162790698,"that, the, bat, origin, animal, as, for"
4456,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.162790698,"a, at, that, the, of, sars-cov-2, this"
4457,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.162790698,"the, of, in, that, this, at, time"
4458,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.162790698,"the, in, of, that, sars-cov-2, this, virus"
4459,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.162790698,"that, covid-19, originated, in, from, a, animal"
4460,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.162790698,"to, with, a, coronavirus, sars-cov-2, zoonotic, origin"
4461,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.162790698,"the, to, bat, ratg13, and, identity, sars-cov-2"
4462,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.162393162,"in, less, the, sars, animal, of, that, palm, tested, positive, for, only, market, virus, to, by, a, closely, related"
4463,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.162393162,"a, of, market, in, that, animal, tested, positive, for, sars, palm, by, only, the, to, less, virus, closely, related"
4464,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.162337662,"in, the, of, researchers, a, year, (april, to, longitudinal, bat, had, samples, total, novel, coronaviruses, single, viruses, genome, sars-related, were, and, sars, from, this, yunnan"
4465,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.162337662,"in, a, of, researchers, year, (april, to, longitudinal, sars-related, coronaviruses, single, yunnan, the, samples, from, total, this, bat, novel, and, had, sars, genome, viruses, were"
4466,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.162162162,"species, of, bats, to, and, the"
4467,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.162162162,"with, the, sars-cov-2, to, bat, genome"
4468,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.162162162,"to, the, that, sars-cov-2, as, natural"
4469,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.162162162,"t, is, that, a, sars-cov-2, to"
4470,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.162162162,"sars-cov-2, to, with, genome, bat, the"
4471,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.162162162,"the, of, sars-cov-2, animal, and, humans"
4472,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.162162162,"bats, are, the, more, of, than"
4473,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.162162162,"that, a, virus, in, similarity, 96.2%"
4474,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.162162162,"sars-cov-2, from, humans, to, bats, the"
4475,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.162162162,"bats, to, the, hosts, of, intermediate"
4476,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.162162162,"sequence, genomic, identity, with, the, sars-cov-2"
4477,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.162162162,"the, of, that, sars-cov-2, is, in"
4478,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.162162162,"the, that, with, bat, and, to"
4479,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.162162162,"the, identical, to, that, of, sars-cov"
4480,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.162162162,"is, that, the, of, to, sars-cov-2"
4481,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.162162162,"the, to, that, sars-cov-2, bat, and"
4482,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.162162162,"that, identity, with, the, sars-cov-2, bat"
4483,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.162162162,"the, of, to, bat, is, that"
4484,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.162162162,"the, of, identity, to, that, sars-cov-2"
4485,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.162162162,"the, sars-cov-2, to, bats, of, be"
4486,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.162162162,"the, of, sars-cov-2, bats, be, to"
4487,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.162162162,"that, sars-cov-2, to, as, the, natural"
4488,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.162162162,"the, of, sars-cov-2, into, humans, from"
4489,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.162162162,"the, natural, origin, to, that, humans"
4490,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.162162162,"hypothesis, the, of, that, sars-cov-2, was"
4491,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.162162162,"sars-cov-2, from, to, are, bat, the"
4492,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.162162162,"a, the, that, to, of, at"
4493,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.162162162,"the, sars-cov-2, of, into, humans, from"
4494,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.162162162,"the, huanan, market, animals, sars-cov-2, of"
4495,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.162162162,"from, the, market, of, for, sars-cov-2"
4496,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.162162162,"the, of, sars-cov-2, animals, huanan, market"
4497,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.162162162,"the, sars-cov-2, huanan, market, that, and"
4498,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.162162162,"lineage, b, cases, and, at, the, huanan, that, of, sars-cov-2, into, in"
4499,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.162162162,"in, more, closely, related, to, the"
4500,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.162162162,"are, the, to, a, market, in"
4501,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.162162162,"the, at, huanan, market, in, and"
4502,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.162162162,"in, related, the, more, closely, to"
4503,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.162162162,"the, huanan, market, that, sars-cov-2, and"
4504,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.162162162,"and, at, the, huanan, market, in"
4505,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.162162162,"to, sars-cov-2, were, and, in, at"
4506,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.162162162,"natural, the, most, of, evidence, yet"
4507,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.162162162,"from, animals, in, the, wet, market"
4508,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.162162162,"the, with, that, and, to, bat"
4509,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.162162162,"that, the, as, to, a, bat"
4510,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.162162162,"the, samples, taken, from, that, this"
4511,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.162162162,"to, be, was, the, as, intermediate"
4512,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.162162162,"the, virus, to, that, had, in"
4513,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.162162162,"the, of, has, identical, to, coronavirus"
4514,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.162162162,"the, of, is, identical, and, to"
4515,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.162162162,"the, intermediate, was, to, be, as"
4516,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.162162162,"a, virus, from, to, the, is"
4517,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.162162162,"is, the, virus, to, sars-cov-2, be"
4518,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.162162162,"the, that, sars-cov-2, is, a, virus"
4519,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.162162162,"the, that, of, has, by, a"
4520,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.162162162,"in, a, the, are, to, market"
4521,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.162162162,"the, was, that, a, part, of"
4522,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.162162162,"to, the, that, humans, natural, origin"
4523,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.162162162,"to, the, in, that, had, virus"
4524,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.162162162,"is, virus, that, its, to, the"
4525,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.162162162,"is, and, to, the, that, in"
4526,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.162162162,"in, the, is, to, that, virus"
4527,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.162162162,"that, is, to, bats, be, the"
4528,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.162162162,"that, the, of, virus, and, to"
4529,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.162162162,"the, in, from, animals, wet, market"
4530,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.162162162,"is, that, the, bats, be, to"
4531,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.162162162,"the, has, to, identical, of, coronavirus"
4532,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.162162162,"has, been, genome, bat, human, sars-cov-2"
4533,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.162162162,"the, of, sars-cov-2, to, bat, genome"
4534,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",Many of these CoVs can infect several animal species as well,0.162162162,"of, covs, species, as, well, these"
4535,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.162162162,"from, a, is, to, that, human"
4536,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.162162162,"to, is, a, virus, from, the"
4537,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.162162162,"the, is, virus, to, a, it"
4538,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.162162162,"the, is, spillover, to, a, virus"
4539,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.162162162,"the, time, is, a, virus, for"
4540,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.162162162,"to, the, sars-cov-2, from, bats, humans"
4541,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.162162162,"are, to, bat, the, sars-cov-2, from"
4542,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.162162162,"from, bats, to, sars-cov-2, the, humans"
4543,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.162162162,"that, sars-cov-2, natural, and, not, a"
4544,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.162162162,"that, the, virus, and, to, of"
4545,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.162162162,"the, covid-19, virus, bats, to, of"
4546,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.162162162,"to, the, of, from, virus, with"
4547,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.162162162,"is, that, of, sars-cov-2, the, genomic"
4548,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.162162162,"the, of, similar, to, that, sars-cov-2"
4549,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.162162162,"that, sars-cov-2, similar, to, the, of"
4550,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.162162162,"is, the, coronavirus, to, sequence, of"
4551,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.162162162,"the, of, as, sars, was, that, from, to, and, more, related, sequence"
4552,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.162162162,"that, sars-cov-2, a, natural, and, not"
4553,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.162162162,"the, sars-, cov-2, that, and, is"
4554,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.162162162,"the, and, is, that, sars-, cov-2"
4555,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.162162162,"of, the, revealed, and, two, novel"
4556,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.162162162,"a, that, the, outbreak, and, animals"
4557,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.162162162,"the, of, that, sars-cov, identical, to"
4558,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.162162162,"from, a, is, in, that, may"
4559,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.162162162,"of, the, novel, revealed, two, and"
4560,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.162162162,"analysis, that, the, of, genome, a"
4561,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.162162162,"analysis, of, revealed, that, the, and"
4562,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.162162162,"the, of, humans, and, animal, sars-cov-2"
4563,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.162162162,"to, the, of, bats, intermediate, hosts"
4564,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.162162162,"a, virus, to, the, it, is"
4565,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.162162162,"of, the, hypothesis, that, is, a"
4566,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.162162162,"the, of, a, and, has, been"
4567,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.162162162,"a, at, to, that, the, of"
4568,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.162162162,"a, that, the, was, to, in"
4569,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.162162162,"the, of, in, that, was, at"
4570,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.162162162,"of, the, in, that, a, with"
4571,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.162162162,"the, hypothesis, is, that, a, of"
4572,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.162162162,"sars-cov-2, to, cov, and, the, of"
4573,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.162162162,"that, the, was, part, of, a"
4574,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.162162162,"hypothesis, that, sars-cov-2, was, the, of"
4575,Many of these CoVs can infect several animal species as well,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.162162162,"of, these, covs, species, as, well"
4576,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.162162162,"the, a, of, and, has, been"
4577,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.162162162,"pangolins, possible, for, sars-cov-2, in, with"
4578,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.162162162,"the, most, as, to, a, bat"
4579,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.162162162,"sars-cov-2, is, that, into, to, the"
4580,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.162162162,"is, sars-cov-2, to, the, that, in"
4581,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.162162162,"in, the, is, to, sars-cov-2, that"
4582,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.162162162,"a, that, in, 96.2%, similarity, virus"
4583,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.162162162,"a, of, has, that, by, the"
4584,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.162162162,"that, the, sars-, cov-2, and, is"
4585,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.162162162,"the, of, sars-, cov-2, is, that"
4586,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.162162162,"bats, of, and, species, to, the"
4587,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.162162162,"in, was, to, that, sars-cov-2, the"
4588,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.162162162,"were, at, sars-cov-2, in, and, to"
4589,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.162162162,"samples, that, taken, from, the, this"
4590,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.162162162,"in, the, that, was, of, at"
4591,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.162162162,"the, for, of, sars-cov-2, from, market"
4592,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.162162162,"a, virus, to, the, is, spillover"
4593,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.162162162,"of, the, sars-cov-2, is, a, virus"
4594,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.162162162,"bat, the, of, sars-cov-2, and, intermediate"
4595,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.162162162,"the, sars-cov-2, that, and, to, bat"
4596,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.162162162,"the, to, are, closely, related, sars-cov-2"
4597,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.162162162,"is, that, the, of, similar, to"
4598,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.162162162,"to, sars-cov-2, is, be, virus, the"
4599,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.162162162,"the, sequence, of, that, from, was, to, as, and, more, related, sars"
4600,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.162162162,"the, of, lineage, b, and, cases, huanan, that, sars-cov-2, into, at, in"
4601,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.162162162,"the, virus, is, to, that, its"
4602,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.162162162,"into, the, that, is, to, sars-cov-2"
4603,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.162162162,"sars-cov-2, the, sequence, identity, with, genomic"
4604,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.162162162,"the, sars-cov-2, identity, with, that, bat"
4605,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.162162162,"the, of, that, is, to, bat"
4606,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.162162162,"of, the, sars-, cov-2, that, is"
4607,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.162162162,"that, is, from, to, a, human"
4608,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.162162162,"may, from, a, that, is, in"
4609,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.162162162,"of, the, genomic, that, sars-cov-2, is"
4610,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.162162162,"a, analysis, of, the, genome, that"
4611,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.162162162,"bats, to, the, of, covid-19, virus"
4612,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.162162162,"the, in, to, market, wuhan,, china"
4613,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.162162162,"analysis, of, the, that, revealed, and"
4614,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.162162162,"the, analysis, that, for, covid-19, virus"
4615,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.162162162,"it, that, the, and, of, bat"
4616,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.162162162,"and, bat, to, the, of, sars-cov-2."
4617,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.162162162,"that, the, outbreak, a, animals, and"
4618,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.162162162,"genome, sars-cov-2, has, been, human, bat"
4619,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.162162162,"sars-cov-2, is, a, virus, that, the"
4620,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.162162162,"the, is, of, sars-cov-2, a, virus"
4621,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.162162162,"it, that, sars-cov-2, to, a, bat"
4622,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.162162162,"t, that, sars-cov-2, is, to, a"
4623,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.162162162,"sars-cov-2, the, with, of, similarity, to"
4624,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.162162162,"of, the, most, evidence, yet, natural"
4625,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.162162162,"evidence, and, that, the, emergence, of"
4626,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.162162162,"studies, that, bats, the, hosts, for"
4627,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.162162162,"analysis, covid-19, virus, that, the, for"
4628,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.162162162,"the, as, a, that, bat, to"
4629,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.162162162,"as, to, the, most, a, bat"
4630,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.162162162,"that, sars-cov-2, a, bat, to, it"
4631,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.162162162,"pangolins, possible, for, sars-cov-2, with, in"
4632,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.162162162,"a, in, the, with, that, of"
4633,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.162162162,"the, is, to, and, that, in"
4634,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.162162162,"the, that, is, in, to, sars-cov-2"
4635,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.162162162,"dbscan, to, that, sars-, cov-2, the, sarbecovirus, of, and, as, are, sars-cov-2"
4636,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.162162162,"bats, are, the, of, more, than"
4637,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.162162162,"the, and, dbscan, to, that, sars-cov-2, of, sarbecovirus, are, sars-, cov-2, as"
4638,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.162162162,"sars-cov-2, and, to, cov, the, of"
4639,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.162162162,"the, is, to, identical, of, and"
4640,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.162162162,"the, is, and, with, to, of"
4641,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.162162162,"that, emergence, the, of, and, evidence"
4642,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.162162162,"and, of, event, between, bat-sl-cov-2, pangolin-cov"
4643,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.162162162,"that, bats, the, hosts, for, studies"
4644,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.162162162,"and, major, minor, bat-sl-cov-2, pangolin-cov, with"
4645,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.162162162,"of, that, it, the, bat, and"
4646,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.162162162,"the, of, sars-cov-2, identity, that, to"
4647,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.162162162,"the, virus, is, to, that, in"
4648,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.162162162,"event, between, bat-sl-cov-2, and, pangolin-cov, of"
4649,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.162162162,"bat-sl-cov-2, major, with, and, pangolin-cov, minor"
4650,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.162162162,"from, with, to, the, of, virus"
4651,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.162162162,"the, of, sars-cov-2, intermediate, bat, and"
4652,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.162162162,"the, that, sars-cov-2, is, in, of"
4653,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.162162162,"a, virus, for, the, time, is"
4654,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.162162162,"the, of, is, with, and, to"
4655,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.162162162,"that, the, was, to, in, sars-cov-2"
4656,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.162162162,"of, the, sequence, coronavirus, is, to"
4657,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.162162162,"of, to, the, bat, and, sars-cov-2."
4658,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.161764706,"in, of, to, the, likely, that, covid-19, this, is, were, market"
4659,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.161764706,"only, a, of, also, have, the, to, from, one, different, animals"
4660,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.161764706,"the, of, that, were, to, market, in, is, this, likely, covid-19"
4661,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.161764706,"the, live, animals, to, in, markets, a, for, of, as, is, sars, was, that, infected, virus, were, by, animal, and, palm, market"
4662,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.161764706,"in, the, sars, animals, live, animal, markets, of, that, palm, for, as, market, virus, was, to, were, infected, by, a, is, and"
4663,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.161764706,"from, also, different, only, one, the, of, a, animals, have, to"
4664,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.161290323,"animal, species, to, and, the"
4665,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.161290323,"sars-cov, and, to, bat, in"
4666,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.161290323,"similar, sequences, and, sars-cov, bat"
4667,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.161290323,"and, bat, coronaviruses, to, sars-cov-2."
4668,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.161290323,"of, sars-cov-2, bats, and, to"
4669,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.161290323,"the, similar, to, and, sars-cov"
4670,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.161290323,"bats, are, of, the, china"
4671,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.161290323,"the, are, in, southern, china"
4672,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.161290323,"that, sars-cov-2, of, a, coronavirus"
4673,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.161290323,"several, have, that, to, sars-cov-2"
4674,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.161290323,"have, to, sars-cov-2, as, the"
4675,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.161290323,"sars-cov-2, a, genome, to, sars-cov"
4676,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.161290323,"sars-cov-2, was, that, identical, to"
4677,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.161290323,"genome, of, has, been, bat"
4678,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.161290323,"natural, origin, of, as, and"
4679,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.161290323,"of, and, has, been, bat"
4680,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.161290323,"a, are, including, the, and"
4681,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.161290323,"in, bat, to, sars-cov, and"
4682,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.161290323,"the, is, in, to, sars-cov-2"
4683,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.161290323,"bat, with, to, sars-cov-2, in"
4684,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.161290323,"the, has, its, in, bats"
4685,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.161290323,"to, is, be, a, virus, that, bats, and, the, as"
4686,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.161290323,"a, virus, that, is, in"
4687,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.161290323,"animal, to, were, and, in"
4688,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.161290323,"sars-cov-2, a, animal, and, is"
4689,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.161290323,"the, of, coronavirus, and, to"
4690,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.161290323,"a, the, is, of, and"
4691,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.161290323,"the, of, sars-, bats, hosts"
4692,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.161290323,"the, of, and, mers-cov, bats"
4693,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.161290323,"the, as, species, mers-cov, that, from, to, civets, hosts, and"
4694,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.161290323,"the, identity, of, sars-cov-2, with"
4695,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",Bats are likely reservoir hosts for SARS-CoV-2,0.161290323,"sars-cov-2, bats, are, hosts, for"
4696,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.161290323,"is, the, zoonotic, sequence, to"
4697,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.161290323,"the, high, homology, to, sars-cov-2"
4698,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.161290323,"in, the, was, outbreak, emerged"
4699,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.161290323,"the, lineage, is, bat, in"
4700,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.161290323,"that, sars-cov-2, to, and, with"
4701,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.161290323,"and, sars-cov-2, to, bats, of"
4702,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.161290323,"the, are, to, sars-cov-2, of"
4703,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.161290323,"the, of, and, are, to"
4704,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.161290323,"bats, are, to, pangolins,, be"
4705,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.161290323,"bats, are, the, sars-cov-2, to"
4706,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","with the first case being linked to  

a seafood market",0.161290323,"the, seafood, market, a, to"
4707,Genetic evidence suggesting otherwise is yet to be presented.,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.161290323,"evidence, is, yet, to, be"
4708,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.161290323,"a, origin, and, in, zoonotic"
4709,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.161290323,"a, zoonotic, origin, the, and"
4710,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.161290323,"the, spillover, that, origin, of"
4711,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.161290323,"into, the, that, to, sars-cov-2"
4712,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.161290323,"that, the, origin, of, sars-cov-2"
4713,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.161290323,"was, that, the, of, sars-cov-2"
4714,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.161290323,"that, the, of, sars-cov-2, before"
4715,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.161290323,"the, of, that, sars-cov-2, was"
4716,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.161290323,"that, are, the, of, sars-cov-2"
4717,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.161290323,"the, that, in, related, to"
4718,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.161290323,"the, is, and, origin, in"
4719,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.161290323,"the, of, was, confirmed, a, at, virus, taken, from, sample"
4720,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.161290323,"is, to, that, in, animal"
4721,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.161290323,"a, spillover, from, an, to"
4722,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.161290323,"virus, from, animals, the, is"
4723,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.161290323,"is, that, the, and, from"
4724,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.161290323,"the, that, is, from, virus"
4725,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.161290323,"to, be, the, of, intermediate"
4726,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.161290323,"with, a, of, the, in"
4727,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.161290323,"bats, a, as, the, is, virus, and, be, that, to"
4728,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.161290323,"the, pangolin, as, intermediate, sars-cov-2"
4729,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.161290323,"a, has, similarity, with, sars-cov-2"
4730,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.161290323,"sars-cov-2, has, been, the, a"
4731,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.161290323,"identity, with, the, sars-cov-2, bat"
4732,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.161290323,"the, virus, to, and, that"
4733,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.161290323,"the, to, be, and, of"
4734,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.161290323,"hosts, and, the, of, is"
4735,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.161290323,"all, evidence, that, a, is"
4736,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.161290323,"the, and, similar, to, sars-cov"
4737,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.161290323,"is, and, origin, the, in"
4738,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.161290323,"that, is, in, animal, to"
4739,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.161290323,"to, that, the, and, virus"
4740,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.161290323,"to, the, in, reservoirs, and"
4741,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.161290323,"in, reservoirs, and, to, the"
4742,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.161290323,"that, the, sars-cov, and, mers-cov"
4743,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.161290323,"to, the, sequence, is, zoonotic"
4744,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.161290323,"that, the, is, of, and"
4745,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.161290323,"the, outbreak, was, emerged, in"
4746,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.161290323,"in, the, was, first, market"
4747,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.161290323,"the, first, was, in, that"
4748,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.161290323,"genome, bat, has, been, of"
4749,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.161290323,"of, the, sars-cov-2, coronavirus, to"
4750,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.161290323,"coronavirus, the, genome, to, of"
4751,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.161290323,"sars-cov-2, the, evolutionary, of, to"
4752,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.161290323,"several, have, that, sars-cov-2, to"
4753,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.161290323,"in, the, has, its, bats"
4754,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.161290323,"that, from, a, to, an"
4755,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.161290323,"from, the, animals, virus, is"
4756,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.161290323,"the, closely, related, to, sars-cov-2"
4757,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.161290323,"of, the, is, to, coronaviruses"
4758,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.161290323,"the, is, isolated, from, in"
4759,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.161290323,"sars-cov-2, is, a, animal, and"
4760,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.161290323,"is, evidence, all, that, a"
4761,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.161290323,"that, sars-cov-2, has, origin, or"
4762,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.161290323,"that, from, the, and, is"
4763,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.161290323,"to, of, coronavirus, and, the"
4764,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.161290323,"analyses, to, the, of, virus"
4765,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.161290323,"analyses, the, virus, of, to"
4766,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.161290323,"the, of, with, to, be"
4767,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.161290323,"the, of, is, to, coronaviruses"
4768,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.161290323,"the, of, sars-cov-2, is, to"
4769,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.161290323,"the, of, and, has, bat"
4770,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.161290323,"the, is, of, hosts, and"
4771,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.161290323,"was, first, isolated, in, and"
4772,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.161290323,"that, sars-cov-2, is, a, bat"
4773,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.161290323,"a, is, that, in, virus"
4774,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.161290323,"the, intermediate, to, be, of"
4775,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.161290323,"the, to, is, most, likely"
4776,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.161290323,"the, genome, of, to, coronavirus"
4777,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.161290323,"are, to, pangolin, and, sars-cov-2."
4778,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.161290323,"the, that, host, of, a"
4779,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.161290323,"that, the, of, a, pan-"
4780,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.161290323,"results, suggest, that, be, the"
4781,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.161290323,"is, the, to, in, covid-19"
4782,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.161290323,"was, in, rhinolophus, yunnan, the"
4783,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.161290323,"the, that, of, spillover, origin"
4784,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.161290323,"be, that, the, an, of"
4785,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.161290323,"and, as, natural, of, origin"
4786,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.161290323,"was, in, that, the, virus, closely, related, to, of, found"
4787,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.161290323,"the, bats, are, of, china"
4788,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.161290323,"and, bat, has, been, of"
4789,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.161290323,"of, the, has, and, bat"
4790,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.161290323,"the, to, and, in, reservoirs"
4791,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.161290323,"genome, sars-cov-2, to, a, sars-cov"
4792,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.161290323,"the, with, similarity, for, sars-cov-2"
4793,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.161290323,"that, sars-cov-2, the, of, before"
4794,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.161290323,"the, sars-cov-2, is, to, in"
4795,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.161290323,"to, the, that, sars-cov-2, into"
4796,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.161290323,"in, related, that, the, to"
4797,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.161290323,"that, sars-cov-2, has, similarity, with"
4798,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.161290323,"the, similar, to, that, sars-cov-2"
4799,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.161290323,"that, sars-cov-2, similar, to, the"
4800,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.161290323,"that, the, a, host, of"
4801,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.161290323,"to, the, high, homology, sars-cov-2"
4802,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.161290323,"the, sars-cov-2, same, with, pangolin-cov"
4803,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.161290323,"from, a, spillover, an, to"
4804,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.161290323,"and, species, to, the, animal"
4805,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.161290323,"were, to, and, animal, in"
4806,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.161290323,"and, species, to, in, the"
4807,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.161290323,"with, sars-cov-2, to, bat, in"
4808,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.161290323,"even, the, that, of, sars-cov-2, is, or, it, artificial, creation."
4809,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.161290323,"the, viruses, closely, related, to"
4810,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.161290323,"in, and, the, virus, for"
4811,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.161290323,"species, to, and, in, the"
4812,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.161290323,"the, of, sars-cov-2, are, to"
4813,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.161290323,"the, of, are, and, to"
4814,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","This suggests that the BANAL series may be able to directly infect  

humans.",0.161290323,"the, to, that, directly, humans."
4815,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.161290323,"for, and, the, of, sars-cov-2"
4816,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.161290323,"was, first, isolated, and, in"
4817,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.161290323,"sars-cov-2, to, closely, related, the"
4818,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.161290323,"covid-19, is, to, the, in"
4819,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.161290323,"that, the, covid-19, and, wuhan, seafood, market,, december, of, 2019"
4820,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.161290323,"of, a, virus, at, the, was, confirmed, from, sample, taken"
4821,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.161290323,"origin, and, a, zoonotic, in"
4822,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.161290323,"the, bat, identity, with, sars-cov-2"
4823,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.161290323,"that, a, of, sars-cov-2, coronavirus"
4824,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.161290323,"that, from, the, virus, is"
4825,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.161290323,"the, sars-, cov-2, is, from"
4826,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.161290323,"bats, the, hosts, of, sars-"
4827,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.161290323,"that, the, pan-, a, of"
4828,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.161290323,"bats, the, of, and, mers-cov"
4829,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.161290323,"of, the, that, covid-19, wuhan, december, and, 2019, seafood, market,"
4830,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.161290323,"is, the, to, be, in"
4831,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.161290323,"the, is, in, lineage, bat"
4832,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.161290323,"the, in, is, isolated, from"
4833,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.161290323,"are, bats, be, to, pangolins,"
4834,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.161290323,"market, in, the, was, first"
4835,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.161290323,"is, a, of, and, the"
4836,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.161290323,"is, that, the, and, of"
4837,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.161290323,"from, as, hosts, that, to, and, mers-cov, the, species, civets"
4838,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.161290323,"that, from, an, to, a"
4839,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.161290323,"a, the, has, been, sars-cov-2"
4840,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",Genetic evidence suggesting otherwise is yet to be presented.,0.161290323,"to, evidence, is, yet, be"
4841,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.161290323,"it, is, that, sars-cov-2, artificial, creation., even, the, of, or"
4842,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.161290323,"was, that, sars-cov-2, identical, to"
4843,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.161290323,"to, that, are, sars-cov-2, and"
4844,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.161290323,"to, that, sars-cov-2, was, from"
4845,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.161290323,"sars-cov-2, to, be, of, the"
4846,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.161290323,"with, to, be, the, of"
4847,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.161290323,"bat, sequences, similar, sars-cov, and"
4848,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.161290323,"results, suggest, that, the, be"
4849,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.161290323,"that, bats, are, hosts, for"
4850,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.161290323,"found, in, the, of, that, was, closely, related, to, virus"
4851,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.161290323,"in, et, al., (2020), found, related, of, covs, genome, to"
4852,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.161290323,"the, that, bat, as, for"
4853,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.161290323,"that, the, is, sars-cov-2, a"
4854,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.161290323,"et, al., (2020), genome, in, related, to, of, covs, found"
4855,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.161290323,"have, sars-cov-2, to, as, the"
4856,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.161290323,"is, that, of, sars-cov-2, the"
4857,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.161290323,"the, of, that, sars-cov-2, we"
4858,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.161290323,"we, that, the, sars-cov-2, is"
4859,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.161290323,"the, that, sars-cov-2, of, origin"
4860,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.161290323,"the, that, are, sars-cov-2, of"
4861,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.161290323,"we, that, sars-cov-2, is, the"
4862,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.161290323,"pangolin, and, are, to, sars-cov-2."
4863,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.161290323,"sars-cov-2, with, that, and, to"
4864,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.161290323,"that, has, similarity, with, sars-cov-2"
4865,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.161290323,"of, the, sars-cov-2, is, to"
4866,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.161290323,"sars-cov-2, and, to, the, of"
4867,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.161290323,"the, of, sars-cov-2, with, sars-cov"
4868,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.161290323,"sars-cov-2, the, of, identity, with"
4869,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.161290323,"the, pangolin-cov, same, sars-cov-2, with"
4870,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.161290323,"bat-sl-cov-2, pangolin-cov, the, of, sars-cov-2"
4871,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.161290323,"bat-sl-cov-2, the, with, pangolin-cov, sars-cov-2"
4872,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.161290323,"the, of, and, for, sars-cov-2"
4873,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.161290323,"the, of, sars-cov-2, bat-sl-cov-2, pangolin-cov"
4874,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.161290323,"in, that, of, sars-cov-2, the"
4875,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.161290323,"the, mers-cov, and, sars-cov, that"
4876,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.161290323,"for, sars-cov-2, similarity, with, the"
4877,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.161290323,"the, sars-cov-2, with, bat-sl-cov-2, pangolin-cov"
4878,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.161290323,"the, sars-cov-2, and, to, pangolin-cov"
4879,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.161290323,"the, virus, for, and, in"
4880,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.161290323,"the, that, an, be, of"
4881,"This suggests that the BANAL series may be able to directly infect  

humans.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.161290323,"that, the, to, directly, humans."
4882,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.161290323,"sars-cov-2, was, from, that, to"
4883,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.161290323,"sars-cov-2, the, pangolin, as, intermediate"
4884,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.161290323,"that, in, the, was, first"
4885,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.161290323,"that, the, for, as, bat"
4886,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.161290323,"that, of, the, is, most"
4887,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.161290323,"are, the, a, including, and"
4888,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.161290323,"the, origin, and, a, zoonotic"
4889,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.161290323,"was, in, yunnan, the, rhinolophus"
4890,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.161290323,"the, is, to, be, in"
4891,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.161290323,"bat, coronaviruses, to, and, sars-cov-2."
4892,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.161290323,"analysis, the, that, sars-cov-2, is"
4893,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.161290323,"is, that, the, sars-cov-2, a"
4894,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.160714286,"the, genome, of, sars-cov, bat, that, a, sequence, to"
4895,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.160714286,"that, of, to, is, a, found, shares, sars-cov-2, the"
4896,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.160714286,"a, genome, was, that, the, is, to, of, found"
4897,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.160714286,"the, of, bats, and, have, as, are, more, than"
4898,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.160714286,"to, the, and, natural, palm, intermediate, for, sars-cov, mers-cov"
4899,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.160714286,"coronavirus, and, in, middle, east, respiratory, syndrome, the, from"
4900,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.160714286,"a, origin, the, by, that, and, zoonotic, in, which"
4901,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.160714286,"evidence, to, sars-cov-2, result, from, a, of, the, that"
4902,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.160714286,"the, origin, and, by, which, a, zoonotic, that, in"
4903,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.160714286,"in, the, middle, east, respiratory, syndrome, coronavirus, from, and"
4904,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.160714286,"to, is, of, the, which, shown, and, was, transmitted"
4905,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.160714286,"the, of, and, shown, is, which, was, transmitted, to"
4906,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.160714286,"intermediate, natural, to, for, sars-cov, and, mers-cov, the, palm"
4907,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.160714286,"the, for, it, is, to, that, sars-cov-2, and, a"
4908,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.160714286,"it, was, by, a, and, which, to, sars-cov-2, the"
4909,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.160714286,"transmission, to, humans, be, through, contact, of, bats,, and"
4910,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.160714286,"that, the, genome, sequence, of, to, a, bat, sars-cov"
4911,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.160714286,"was, in, closely, related, which, similar, to, sars-cov-2, the"
4912,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.160714286,"a, it, that, the, sars-cov-2, and, for, to, is"
4913,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.160714286,"a, is, to, in, the, that, it, not, human"
4914,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.160714286,"found, that, the, of, sars-cov-2, is, to, a, shares"
4915,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.160714286,"that, sars-cov-2, from, a, to, in, an, intermediate, host"
4916,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.160714286,"evidence, to, the, that, sars-cov-2, a, result, of, from"
4917,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.160714286,"the, as, species, of, most, likely, to, bat, and"
4918,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.160714286,"a, it, was, the, sars-cov-2, and, to, which, by"
4919,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.160714286,"in, the, which, sars-cov-2, was, closely, related, to, similar"
4920,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.160714286,"the, of, covid-19, were, with, huanan, market, in, wuhan"
4921,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.160714286,"in, the, it, is, not, to, that, human, a"
4922,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.160714286,"this, is, similarity, sars-cov-2, pangolin, to, the, that, in"
4923,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.160714286,"in, the, rbd, of, is, to, sars-cov-2, that, pangolin"
4924,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.160714286,"of, covid-19, with, wuhan, the, huanan, market, were, in"
4925,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.160714286,"contact, humans, and, bats,, transmission, of, to, through, be"
4926,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.160714286,"the, species, most, likely, to, as, of, bat, and"
4927,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.160714286,"that, from, to, an, intermediate, host, a, in, sars-cov-2"
4928,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.160714286,"found, that, sars-cov-2, sequences, are, to, and, on, of"
4929,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.160714286,"was, found, that, the, genome, of, is, to, a"
4930,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.160714286,"pangolin, similarity, to, sars-cov-2, in, the, this, that, is"
4931,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.160714286,"bats, are, the, have, as, of, and, more, than"
4932,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.160714286,"found, are, to, that, of, sars-cov-2, on, and, sequences"
4933,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.160714286,"pangolin, to, sars-cov-2, in, the, rbd, that, is, of"
4934,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.160583942,"the, and, for, of, all, suggesting, a, exposure, or, to, however,, were, in, sars, live, animal, palm, infected, other, by, contrast,, at"
4935,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.160583942,"at, infected, to, a, palm, however,, animal, in, for, the, or, by, contrast,, sars, all, exposure, live, were, suggesting, of, and, other"
4936,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.160493827,"a, from, was, market, in, that, the, virus, is, to, of, were, found"
4937,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.160493827,"in, a, of, to, the, virus, that, was, is, from, were, market, found"
4938,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.160377358,"anti-smuggling, march, 2019;, and, were, in, by, (lam, et, al., 2020;, liu, xiao, 2020),, seized, positive, sars-cov-2-like"
4939,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.160377358,"seized, in, anti-smuggling, and, march, by, (lam, et, al., 2020;, liu, 2019;, xiao, 2020),, were, positive, sars-cov-2-like"
4940,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.160305344,"in, the, of, palm, civets, as, an, intermediate, host, sars, a, at, found, that, samples, taken, from, infected, were, to, and"
4941,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.160305344,"as, a, of, the, palm, civets, at, and, were, in, an, to, sars, samples, infected, found, that, taken, from, intermediate, host"
4942,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.16,"is, in, to, sars-cov-2"
4943,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.16,"the, in, southern, china"
4944,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.16,"was, the, of, sars-cov-2, is, to, a, it"
4945,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.16,"sars-cov-2, is, to, be, a, of, and, the"
4946,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.16,"the, genetic, of, sars-cov-2, other, coronaviruses, to, be"
4947,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.16,"t, was, that, the, sequence, sars-cov-2, is, a"
4948,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.16,"a, virus, sequence, that, the, sars-cov-2, in, its"
4949,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.16,"had, from, its, before, was, by, the, that, sars-cov-2, in, a, laboratory"
4950,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.16,"sars-cov-2, have, host, to, as, several, identified, bat"
4951,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.16,"a, of, the, was, it, is, to, sars-cov-2"
4952,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.16,"t, is, that, sars-cov-2, was, a, the, sequence"
4953,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.16,"the, of, it, is, to, that, sars-cov-2, a"
4954,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.16,"it, is, that, sars-cov-2, a, the, of, genome"
4955,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.16,"the, natural, of, and"
4956,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.16,"the, sars-cov, of, bat, is, and, sequence, with"
4957,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.16,"are, to, most, of"
4958,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.16,"similar, to, of, sars-cov-2"
4959,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.16,"and, a, similarity, in, is, the, to, human"
4960,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.16,"the, sars-cov-2, and, to, be, a, of, is"
4961,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.16,"bats, and, be, the"
4962,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.16,"the, of, natural, and"
4963,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.16,"to, virus, that, from, and, the, as, intermediate"
4964,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",Bats are likely reservoir hosts for SARS-CoV-2,0.16,"bats, hosts, for, sars-cov-2"
4965,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.16,"the, natural, of, for"
4966,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.16,"sars-cov-2, are, to, and"
4967,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","with the first case being linked to  

a seafood market",0.16,"a, the, with, to"
4968,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","with the first case being linked to  

a seafood market",0.16,"to, the, seafood, market"
4969,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.16,"several, have, identified, sars-cov-2, to, bat, as, host"
4970,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.16,"are, and, transmitted, from, to, a, in, china"
4971,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.16,"a, bat, from, in, china, identified, coronaviruses, sars-cov-2"
4972,"this one jumped from bats origin  

into humans","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.16,"from, origin, into, humans"
4973,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.16,"evidence, to, that, the, of, as, origin, sars-cov-2"
4974,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.16,"of, the, clustering, in, and, that, sars-cov-2, with"
4975,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.16,"cases, in, two, lineage, the, that, a, to"
4976,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.16,"positive, from, the, market, presence, of, in, sars-cov-2"
4977,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.16,"in, a, that, the, two, lineage, cases, to"
4978,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.16,"is, that, had, in"
4979,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.16,"was, that, the, in, have, market, live, were, sold, as, a, of"
4980,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.16,"the, virus, to, that, has, with, and, a"
4981,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.16,"and, the, natural, of"
4982,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.16,"the, was, to, be"
4983,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.16,"this, in, the, of, which, that, to, virus"
4984,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.16,"is, to, the, that, has, from, an, and"
4985,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.16,"from, as, intermediate, that, virus, to, and, the"
4986,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.16,"that, genome, to, pangolin, and, a, the, of"
4987,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.16,"has, the, from, bat"
4988,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.16,"the, identity, sars-cov-2, with"
4989,"Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.16,"based, on, the, of, that, to, animal, is"
4990,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.16,"transmitted, from, to, a, are, and, in, china"
4991,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.16,"genetic, show, that, used"
4992,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.16,"the, animal, reservoirs, and"
4993,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.16,"with, the, sars-cov, and, is, bat, of, sequence"
4994,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.16,"bats, the, reservoir, of"
4995,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.16,"be, the, possible, genomic, bat, that, bats, could"
4996,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.16,"to, the, therefore, that, bats, could, be, possible"
4997,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.16,"in, a, of, have, the, that, was, were, sold, live, market, as"
4998,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.16,"the, have, source, in, market, or, infected, may"
4999,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.16,"genomic, that, bat, bats, could, be, the, possible"
5000,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.16,"sars-cov-2, to, of, the"
5001,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.16,"the, of, to, sars-cov-2"
5002,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.16,"sars-cov-2, et, al.,, 2020), and, cov, the, of"
5003,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.16,"the, from, bat, has"
5004,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.16,"human, are, the, of"
5005,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.16,"to, human, animal, zoonotic"
5006,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.16,"transmitted, to, human, a"
5007,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.16,"coronaviruses, closely, related, to"
5008,"bats are also important reservoir species for a great 

range of coronaviruses","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.16,"bats, also, of, coronaviruses"
5009,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.16,"the, infected, in, may, have, market, or, source"
5010,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.16,"genome, of, the, covid-19, virus, with, and, showed"
5011,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.16,"of, the, genome, covid-19, virus, and, showed, with"
5012,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.16,"animal, to, human, zoonotic"
5013,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.16,"that, is, sars-cov-2, a"
5014,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.16,"are, the, of, and"
5015,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.16,"animal, the, are, other"
5016,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.16,"the, of, sars-cov-2, and"
5017,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.16,"most, of, are, to"
5018,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Bats are natural hosts of many of the known  

coronaviruses",0.16,"bats, are, the, hosts"
5019,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.16,"hypothesis, is, to, the, that, has, been, and"
5020,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.16,"closely, related, to, coronaviruses"
5021,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.16,"the, that, be, of"
5022,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.16,"the, of, human, are"
5023,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.16,"the, of, sars-cov-2, with"
5024,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.16,"cov, the, of, sars-cov-2, et, al.,, 2020), and"
5025,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.16,"sars-cov-2, have, in, bats"
5026,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.16,"that, the, be, of"
5027,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.16,"of, the, natural, for"
5028,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.16,"sars-cov-2, of, the, sarbecovirus"
5029,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.16,"this, of, to, the, in, which, that, virus"
5030,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.16,"this, sars-cov-2, ratg13, pangolin, to, the, that, in"
5031,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","this one jumped from bats origin  

into humans",0.16,"into, humans, from, origin"
5032,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.16,"transmitted, to, a, human"
5033,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.16,"sars-cov-2, has, similarity, to"
5034,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.16,"is, that, sars-cov-2, the, covid-19, pandemic, of, or"
5035,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.16,"is, to, sars-cov-2, in"
5036,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.16,"is, that, sars-cov-2, related"
5037,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.16,"that, the, of, sars-cov-2, is, to, a, it"
5038,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.16,"the, virus, a, that, has, with, and, to"
5039,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.16,"for, the, of, and, that, virus, a, in, human, this, with, to"
5040,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.16,"the, that, sars-cov-2, is"
5041,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.16,"is, that, sars-cov-2, the"
5042,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.16,"is, the, to, sars-cov-2"
5043,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.16,"the, sars-cov-2, is, to"
5044,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","bats are also important reservoir species for a great 

range of coronaviruses",0.16,"of, also, coronaviruses, bats"
5045,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.16,"a, ratg13, in, the, viral, for, to, human"
5046,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.16,"in, the, market, positive, from, presence, of, sars-cov-2"
5047,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.16,"that, the, genome, of, sars-cov-2, is, a, it"
5048,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.16,"is, that, the, of, sars-cov-2, or, covid-19, pandemic"
5049,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.16,"the, and, animal, reservoirs"
5050,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.16,"in, china, the, virus, closely, related, to, were"
5051,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.16,"in, a, team, to, the, which, discovered, two, coronaviruses,, and, at, whole, genome, closely, related, other"
5052,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.16,"the, is, to, sars-cov-2"
5053,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.16,"is, the, most, sars-cov-2"
5054,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.16,"in, the, of, virus, for, to, that, with, human, and, this, a"
5055,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.16,"discovered, in, a, team, two, other, closely, related, coronaviruses,, and, which, to, at, the, whole, genome"
5056,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.16,"and, to, the, evidence, of, natural, origin, is"
5057,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.16,"that, sars-cov-2, a, the, virus, its, sequence, in"
5058,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.16,"that, is, related, sars-cov-2"
5059,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.16,"genetic, used, show, that"
5060,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.16,"in, the, is, identical, to, that, which, bind"
5061,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.16,"that, of, virus, similar, to, pangolins, the, sars-cov-2"
5062,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","In the 

case of MERS, dromedaries were the principal host.",0.16,"the, of, were, in"
5063,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.16,"based, on, the, of, that, is, animal, to"
5064,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",The COVID-19 most likely developed from bat origin coronaviruses,0.16,"the, most, likely, bat"
5065,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.16,"to, are, in, and"
5066,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.16,"the, in, is, to"
5067,"In the 

case of MERS, dromedaries were the principal host.","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.16,"in, the, of, were"
5068,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.16,"bats, be, the, and"
5069,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.16,"the, are, animal, other"
5070,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.16,"that, sars-cov-2, was, from, a, laboratory, by, had, the, its, in, before"
5071,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.16,"of, sars-cov-2, was, the"
5072,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.16,"the, to, sars-cov-2, be"
5073,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.16,"the, sars-cov-2, identical, to"
5074,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.16,"the, of, evidence, sars-cov-2, is, has, been, in"
5075,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.16,"sars-cov-2, are, and, to"
5076,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.16,"that, sars-cov-2, to, and"
5077,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.16,"bat, ratg13, sars-cov-2, than"
5078,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.16,"the, has, an, is, to, that, and, from"
5079,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.16,"the, hypothesis, is, that, to, and, has, been"
5080,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.16,"the, sars-cov-2, to, be, of, genetic, other, coronaviruses"
5081,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.16,"the, virus, closely, related, to, were, in, china"
5082,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.16,"most, that, a, likely, the, sars-cov-2, is, to"
5083,"Bats are natural hosts of many of the known  

coronaviruses","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.16,"bats, are, hosts, the"
5084,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.16,"suggest, that, a, of, virus, to, and, the"
5085,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.16,"a, is, the, to, in, similarity, human, and"
5086,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.16,"to, a, in, ratg13, the, human, for, viral"
5087,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.16,"the, pangolins, of, similar, to, that, sars-cov-2, virus"
5088,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.16,"of, a, suggest, that, the, virus, to, and"
5089,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.16,"the, of, with, and, clustering, that, sars-cov-2, in"
5090,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.16,"bat, sars-cov-2, than, ratg13"
5091,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.16,"sars-cov-2, bat, cov, ratg13"
5092,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.16,"the, of, sars-cov-2, sarbecovirus"
5093,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.16,"that, to, therefore, bats, could, be, the, possible"
5094,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.16,"this, in, the, that, sars-cov-2, to, ratg13, pangolin"
5095,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.16,"bat, cov, ratg13, sars-cov-2"
5096,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.16,"the, sars-cov-2, are, cluster, with, bat, cov, ratg13"
5097,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.16,"evidence, to, the, that, sars-cov-2, as, of, origin"
5098,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.16,"the, a, genome, of, to, that, pangolin, and"
5099,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.16,"bat, cov, the, are, sars-cov-2, cluster, with, ratg13"
5100,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.16,"sars-cov-2, that, to, and"
5101,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.16,"to, sars-cov-2, and, pangolin-cov"
5102,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.16,"is, the, of, sars-cov-2"
5103,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.16,"the, identity, with, sars-cov-2"
5104,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.16,"with, sars-cov-2, the, of"
5105,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.16,"the, sars-cov-2, and, pangolin-cov"
5106,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.16,"the, in, and, to"
5107,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.16,"the, and, to, in"
5108,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.16,"are, in, and, to"
5109,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.16,"sars-cov-2, to, and, pangolin-cov"
5110,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.16,"the, sars-cov-2, pangolin-cov, and"
5111,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.16,"is, identical, to, in, the, which, that, bind"
5112,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.16,"been, in, the, evidence, of, sars-cov-2, has, is"
5113,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.16,"sars-cov-2, from, a, identified, coronaviruses, in, bat, china"
5114,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.16,"of, sars-cov-2, similar, to"
5115,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.15942029,"that, a, recombination, of, virus, with, to, and, are, the, for"
5116,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.15942029,"are, and, a, to, that, in, humans,, respiratory, syndrome, middle, east"
5117,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.15942029,"in, the, of, was, found, that, virus, to, closely, related, sequence"
5118,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.15942029,"the, and, has, in, ability, to, bind, suggesting, that, these, are"
5119,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.15942029,"is, a, natural, virus, that, found, through, on, to, the, for"
5120,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.15942029,"found, in, the, of, sequence, that, was, closely, related, to, virus"
5121,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.15942029,"the, on, is, for, natural, found, a, virus, to, through, that"
5122,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.15942029,"are, a, for, the, recombination, of, virus, and, with, that, to"
5123,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.15942029,"in, a, middle, east, respiratory, syndrome, humans,, that, are, to, and"
5124,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.15942029,"has, in, the, and, are, to, bind, suggesting, that, these, ability"
5125,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.159090909,"have, to, genetic, and, coronaviruses, in, bat"
5126,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.159090909,"and, of, in, many, species,, which, more"
5127,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.159090909,"that, with, the, have, to, as, host"
5128,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.159090909,"sars-cov-2, is, a, that, found, to, the"
5129,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.159090909,"is, sars-cov-2, bat, cov, to, the, that"
5130,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.159090909,"genome, se-, has, and, of, virus, bat"
5131,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.159090909,"and, in, of, more, species,, many, which"
5132,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.159090909,"to, the, that, sars-cov-2, of, humans, origin"
5133,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.159090909,"the, that, to, be, sars-cov-2, and, of"
5134,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.159090909,"can, be, that, the, between, and, of"
5135,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.159090909,"is, similarity, and, to, the, that, in"
5136,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.159090909,"the, sars-cov-2, to, humans, from, bats, of"
5137,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.159090909,"that, the, of, and, has, been, bats"
5138,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.159090909,"the, of, and, that, sars-cov-2, is, to"
5139,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.159090909,"with, the, of, shares, 96%, genome, and"
5140,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.159090909,"the, in, pangolins, of, to, sars-cov-2, this"
5141,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.159090909,"in, bat, coronaviruses, have, genetic, to, and"
5142,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.159090909,"the, origin, of, to, that, humans, sars-cov-2"
5143,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.159090909,"the, to, sars-cov-2, from, of, a, bat"
5144,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.159090909,"the, from, that, sars-cov-2, to, a, bat"
5145,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.159090909,"of, sars-cov-2, from, the, huanan, animals, for"
5146,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.159090909,"the, of, be, to, that, and, sars-cov-2"
5147,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.159090909,"that, sars-cov-2, jumped, the, and, humans, animal"
5148,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.159090909,"that, a, in, animal, evidence, covid-19, originated"
5149,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.159090909,"a, virus, that, with, on, to, the"
5150,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.159090909,"the, virus, been, in, market, or, to"
5151,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.159090909,"that, the, of, and, coronavirus, has, from"
5152,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.159090909,"that, sars-cov-2, is, to, bats, be, the"
5153,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.159090909,"the, that, sars-cov-2, originated, and, from, a"
5154,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.159090909,"that, the, from, a, transmitted, to, and"
5155,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.159090909,"the, bats, to, as, sars-cov-2, intermediate, and"
5156,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.159090909,"the, genome, of, has, to, coronavirus, bat"
5157,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.159090909,"the, to, sars-cov-2, has, been, with, a"
5158,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.159090909,"a, that, the, sars-cov-2, and, to, by"
5159,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.159090909,"the, analysis, of, that, sars-cov-2, to, virus"
5160,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.159090909,"the, of, sars-cov-2, that, and, is, to"
5161,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.159090909,"analysis, of, the, that, and, sars-cov-2, is"
5162,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.159090909,"the, of, that, as, no, evidence, was"
5163,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.159090909,"to, sars-cov-2, is, be, that, bats, the"
5164,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.159090909,"in, the, of, a, was, patients, market"
5165,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.159090909,"the, has, genome, of, to, coronavirus, bat"
5166,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.159090909,"a, to, that, sars-cov-2, by, the, and"
5167,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.159090909,"sars-cov-2, was, also, to, ace2, which, the"
5168,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.159090909,"the, of, it, that, has, been, human"
5169,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.159090909,"sars-cov-2, and, bat, similarity, to, the, of"
5170,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.159090909,"to, the, market, in, been, virus, or"
5171,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.159090909,"the, animal, and, that, sars-cov-2, jumped, humans"
5172,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.159090909,"another, that, the, is, from, animal, species"
5173,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.159090909,"it, is, that, likely, sars-cov-2, very, to"
5174,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.159090909,"has, identity, and, with, the, of, bat"
5175,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.159090909,"sars-cov-2, a, that, originated, from, and, the"
5176,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.159090909,"to, a, that, from, and, transmitted, the"
5177,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.159090909,"live, a, and, in, the, that, to"
5178,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.159090909,"virus, genome, se-, and, bat, has, of"
5179,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.159090909,"of, the, has, and, identity, with, bat"
5180,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.159090909,"from, the, bat, and, 93.1%, sequence, with"
5181,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.159090909,"the, for, of, sars-cov-2, from, animals, huanan"
5182,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.159090909,"the, from, that, which, includes, wild, animals"
5183,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.159090909,"no, evidence, that, the, was, as, of"
5184,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.159090909,"that, the, virus, and, transmitted, to, of"
5185,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.159090909,"in, a, of, to, with, coronavirus, that"
5186,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.159090909,"a, to, bat, the, of, sars-cov-2, from"
5187,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.159090909,"in, an, from, of, to, sars-cov-2, the"
5188,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.159090909,"the, in, of, an, to, sars-cov-2, was"
5189,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.159090909,"the, of, scientific, that, a, in, for"
5190,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.159090909,"analysis, of, to, that, sars-cov-2, the, virus"
5191,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.159090909,"the, genome, of, shares, with, and, 96%"
5192,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.159090909,"a, the, has, been, to, with, sars-cov-2"
5193,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.159090909,"it, has, been, that, the, of, human"
5194,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.159090909,"coronaviruses, were, sars-cov-2, in, rhinolophus, and, from"
5195,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.159090909,"the, analysis, of, and, that, sars-cov-2, is"
5196,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.159090909,"the, to, sars-cov-2, in, from, an, of"
5197,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.159090909,"sequence, and, 93.1%, with, the, from, bat"
5198,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.159090909,"that, the, a, laboratory, was, and, to"
5199,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.159090909,"of, it, is, to, the, and, for"
5200,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.159090909,"a, that, the, was, to, laboratory, and"
5201,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.159090909,"the, of, closely, related, virus, to, is"
5202,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.159090909,"due, to, the, of, zoonotic, a, virus"
5203,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.159090909,"to, sars-cov-2, bats, and, the, as, intermediate"
5204,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.159090909,"sars-cov-2, and, bat, to, the, that, in"
5205,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.159090909,"other, closely, related, to, in, the, and"
5206,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.159090909,"in, southern, china, and, were, for, viruses"
5207,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.159090909,"is, the, bat, coronavirus, to, closest, sars-cov-2,"
5208,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.159090909,"the, is, of, to, closely, related, virus"
5209,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.159090909,"the, and, other, closely, related, to, in"
5210,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.159090909,"the, of, with, huanan, seafood, market, wuhan"
5211,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.159090909,"that, the, a, live, in, to, and"
5212,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.159090909,"found, that, the, sars-cov-2, is, to, a"
5213,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.159090909,"on, the, virus, a, that, with, to"
5214,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.159090909,"a, virus, that, with, the, sars-cov-2, its"
5215,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.159090909,"coronaviruses, from, rhinolophus, and, were, in, sars-cov-2"
5216,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.159090909,"sars-cov-2, a, virus, that, its, with, the"
5217,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.159090909,"the, sars-cov-2, to, pangolins, in, of, this"
5218,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.159090909,"the, to, sars-cov-2, was, in, an, of"
5219,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.159090909,"that, evidence, covid-19, originated, in, a, animal"
5220,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.159090909,"that, from, the, which, includes, wild, animals"
5221,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.159090909,"is, that, the, species, from, another, animal"
5222,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.159090909,"the, that, virus, to, of, and, transmitted"
5223,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.159090909,"the, of, to, it, is, for, and"
5224,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.159090909,"the, huanan, seafood, market, of, wuhan, with"
5225,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.159090909,"was, the, patients, in, market, a, of"
5226,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.159090909,"for, and, viruses, were, in, southern, china"
5227,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.159090909,"was, the, sars-cov-2, also, ace2, to, which"
5228,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.159090909,"be, the, that, sars-cov-2, research, or, for"
5229,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.159090909,"a, to, bat, that, the, sars-cov-2, from"
5230,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.159090909,"results, the, clustering, and, that, sars-cov-2, a"
5231,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.159090909,"also, that, the, sars-cov-2, and, bat, pangolin"
5232,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.159090909,"is, very, it, likely, that, sars-cov-2, to"
5233,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.159090909,"for, recombination, and, that, the, of, sars-cov-2"
5234,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.159090909,"the, results, clustering, that, sars-cov-2, a, and"
5235,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.159090909,"has, been, that, bats, and, the, of"
5236,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.159090909,"the, has, that, of, and, coronavirus, from"
5237,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.159090909,"the, of, this, that, sars-cov-2, has, been"
5238,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.159090909,"that, the, sars-cov-2, is, to, bat, cov"
5239,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.159090909,"is, the, to, that, in, similarity, and"
5240,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.159090909,"the, to, that, sars-cov-2, bat, in, and"
5241,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.159090909,"the, that, sars-cov-2, also, bat, and, pangolin"
5242,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.159090909,"that, recombination, of, and, the, for, sars-cov-2"
5243,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.159090909,"the, of, can, be, that, between, and"
5244,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.159090909,"the, rbd, of, to, sars-cov-2, aa, that"
5245,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.159090909,"the, rbd, of, aa, to, that, sars-cov-2"
5246,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.159090909,"the, of, zoonotic, due, to, a, virus"
5247,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.159090909,"the, in, scientific, that, for, a, of"
5248,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.159090909,"that, the, of, sars-cov-2, this, has, been"
5249,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.159090909,"that, sars-cov-2, has, the, at, of, virus"
5250,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.159090909,"research, that, or, be, the, for, sars-cov-2"
5251,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.159090909,"a, coronavirus, in, with, that, to, of"
5252,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.159090909,"closest, bat, coronavirus, to, sars-cov-2,, is, the"
5253,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.159090909,"have, that, to, with, as, the, host"
5254,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.159090909,"the, similarity, sars-cov-2, and, of, to, bat"
5255,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.158730159,"the, of, that, into, from, a, evidence, humans, as, to"
5256,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.158730159,"that, of, to, humans, an, is, sars-cov-2, analysis, sequences, the"
5257,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.158730159,"that, transmission, of, to, humans, an, intermediate, is, sars-cov-2, species"
5258,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.158730159,"the, analysis, of, sequences, that, sars-cov-2, is, an, to, humans"
5259,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.158730159,"is, humans, that, transmission, of, sars-cov-2, to, an, intermediate, species"
5260,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.158730159,"the, to, it, that, has, been, in, with, of, living"
5261,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.158730159,"evidence, to, the, that, as, a, of, into, humans, from"
5262,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.158730159,"are, viruses, the, in, and, evidence, that, bats, pangolins, for"
5263,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.158730159,"to, of, in, living, the, it, has, been, that, with"
5264,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.158730159,"evidence, that, bats, are, the, and, viruses, in, pangolins, for"
5265,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.158730159,"that, the, sars-cov-2, and, bat, cov, ratg13, guangdong, pangolin, is"
5266,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.158730159,"the, and, that, sars-cov-2, is, bat, cov, ratg13, guangdong, pangolin"
5267,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.157894737,"in, of, bats, to, sars-cov-2, and"
5268,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.157894737,"genetic, of, more, than, and, bats"
5269,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.157894737,"the, sequences, within, are, to, sars-cov"
5270,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.157894737,"sars-cov-2, genome, virus, is, identical, to"
5271,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.157894737,"of, southern, are, in, the, same"
5272,"In the 

case of MERS, dromedaries were the principal host.","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.157894737,"in, the, of"
5273,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.157894737,"from, virus, to, sars-cov, and, the, into, masked, palm"
5274,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.157894737,"the, of, have, which, to, and, virus, sars-cov, masked, palm, civet, (paguma"
5275,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.157894737,"that, of, been, origin, by, a"
5276,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.157894737,"a, is, that, virus, and, thus"
5277,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.157894737,"to, the, that, sars-cov-2, a, of"
5278,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.157894737,"a, of, to, that, sars-cov-2, the"
5279,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.157894737,"sars-cov-2, bat, identity, to, the, of"
5280,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.157894737,"is, the, to, in, sequence, and"
5281,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.157894737,"the, to, sars-cov-2, bat, in, and"
5282,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.157894737,"similar, to, sars-cov-2"
5283,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.157894737,"most, of, sars-cov-2"
5284,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.157894737,"that, of, bats, to, an, host, is, a, coronavirus, in, with, the"
5285,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.157894737,"is, that, bats, are, the, for, as, to, a"
5286,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.157894737,"and, is, thus, a, virus, that"
5287,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.157894737,"the, and, is, to, in, sequence"
5288,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.157894737,"a, to, that, the, and, virus"
5289,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.157894737,"highly, malayan, pangolins, (manis, of, as"
5290,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.157894737,"the, is, to, a, of, and"
5291,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.157894737,"animal, a, and, the, spillover, to"
5292,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.157894737,"the, of, sars-cov-2, is, a, animal"
5293,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.157894737,"the, is, and, an, to, of"
5294,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.157894737,"t, that, the, and, bats, of"
5295,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.157894737,"most, of, the, been, that, by"
5296,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.157894737,"the, has, been, species, of, that, most, by, and"
5297,"civet cats and raccoon dogs  

are the intermediate hosts","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.157894737,"and, the, hosts"
5298,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.157894737,"to, the, and, sars-cov, into, from, virus, masked, palm"
5299,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.157894737,"of, covid-19, the, with, early, through"
5300,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.157894737,"at, the, sequence, of, with, sars-cov-2"
5301,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",Bats are likely reservoir hosts for SARS-CoV-2,0.157894737,"bats, are, for"
5302,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.157894737,"to, sars-cov-2, is, a, from, the"
5303,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.157894737,"the, is, a, zoonotic, origin, to"
5304,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.157894737,"to, bat, that, the, of, sars-cov-2"
5305,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.157894737,"and, that, sars-cov, is, of, bat"
5306,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.157894737,"of, that, the, to, bat, and"
5307,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.157894737,"of, the, and, that, sars-cov-2, with"
5308,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.157894737,"that, the, sars-cov-2, and, bat, is"
5309,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","civet cats and raccoon dogs  

are the intermediate hosts",0.157894737,"the, hosts, and"
5310,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","civet cats and raccoon dogs  

are the intermediate hosts",0.157894737,"the, are, and"
5311,"expended to make the simple point 

that COVID-19 had a natural origin.","with the first case being linked to  

a seafood market",0.157894737,"to, the, a"
5312,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.157894737,"the, of, sars-cov-2, has, been, to"
5313,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.157894737,"is, the, to, sars-cov-2, be, in"
5314,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.157894737,"the, that, not, been, by, a"
5315,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.157894737,"several, have, genetic, similarity, between, sars-cov-2, and, to, bat"
5316,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.157894737,"that, the, of, sars-cov-2, to, a"
5317,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.157894737,"as, to, the, of, a, spillover"
5318,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.157894737,"the, of, to, that, sars-cov-2, from"
5319,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.157894737,"through, the, that, are, sars-cov-2, and"
5320,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.157894737,"studies, have, that, are, the, and"
5321,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.157894737,"the, of, sars-cov-2, that, to, bat"
5322,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.157894737,"the, viruses, are, to, sars-cov-2, of"
5323,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.157894737,"of, at, the, huanan, market, from"
5324,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.157894737,"that, sars-cov-2, through, and, are, the"
5325,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.157894737,"the, to, that, are, sars-cov-2, and"
5326,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.157894737,"the, that, sars-cov-2, of, and, to"
5327,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.157894737,"the, of, from, at, huanan, market"
5328,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.157894737,"the, virus, was, from, a, market"
5329,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.157894737,"most, animal, coronavirus, in, the, other"
5330,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.157894737,"the, more, closely, related, to, than"
5331,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.157894737,"there, is, that, wuhan, to, covid-19"
5332,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.157894737,"that, from, a, to, in, an"
5333,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.157894737,"sars-cov-2, is, a, that, to, cause, the, most, pandemic"
5334,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.157894737,"that, the, from, seafood, animals, and"
5335,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.157894737,"and, that, the, covid-19, to, bat"
5336,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.157894737,"a, sequence, that, 96.2%, the, bat"
5337,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.157894737,"the, early, of, covid-19, with, through"
5338,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.157894737,"the, huanan, market, wuhan, in, of, cases, january, by, with, early, covid-19"
5339,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.157894737,"to, the, a, from, sars-cov-2, is"
5340,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.157894737,"available, that, sars-cov-2, a, and, is"
5341,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.157894737,"and, a, to, the, bats, be, pangolin, as, intermediate"
5342,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","Bats have been reported as being the rich source of 

coronaviruses",0.157894737,"bats, the, of"
5343,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.157894737,"similar, to, of, sars-cov-2, the, protein"
5344,The COVID-19 most likely developed from bat origin coronaviruses,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.157894737,"the, from, bat"
5345,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.157894737,"a, the, to, that, virus, and"
5346,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.157894737,"the, to, date, that, sars-cov-2, and"
5347,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.157894737,"one, the, of, pangolin, to, intermediate"
5348,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.157894737,"that, is, transmitted, an, animal, to"
5349,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.157894737,"a, virus, the, market, was, from"
5350,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.157894737,"that, the, infected, in, china, have, market, animals, a"
5351,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.157894737,"of, covid-19, that, most, to, the"
5352,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.157894737,"the, is, that, virus, a, of"
5353,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.157894737,"the, of, huanan, seafood, wholesale, in"
5354,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.157894737,"t, that, bats, and, the, of"
5355,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.157894737,"of, the, sequence, virus, and, identity"
5356,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.157894737,"the, is, of, zoonotic, to, virus"
5357,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.157894737,"the, and, is, of, zoonotic, to"
5358,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.157894737,"may, have, the, from, or, in"
5359,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.157894737,"sars-cov-2, to, related, bat, bats, the"
5360,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.157894737,"the, in, market, that, was, outbreak"
5361,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.157894737,"have, that, the, in, infected, animals, a, market, china"
5362,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.157894737,"the, was, a, seafood, market, of, wuhan, with, pneumonia"
5363,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.157894737,"the, sars-cov-2, has, been, to, of"
5364,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.157894737,"bat, coronavirus, to, sars-cov-2, the, genome"
5365,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.157894737,"virus, is, identical, to, sars-cov-2, genome"
5366,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.157894737,"sars-cov-2, have, to, several, genetic, similarity, between, and, bat"
5367,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.157894737,"of, that, sars-cov, and, is, bat"
5368,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.157894737,"is, that, bats, most, likely, bat"
5369,The COVID-19 most likely developed from bat origin coronaviruses,The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.157894737,"the, covid-19, most"
5370,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.157894737,"that, is, an, animal, transmitted, to"
5371,"atural  

selection in an animal host before zoonotic  

transfer;","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.157894737,"an, animal, zoonotic"
5372,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.157894737,"sars-cov-2, related, to, bat, bats, the"
5373,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.157894737,"coronaviruses, related, to, sars-cov-2, bats, from"
5374,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.157894737,"bats, humans, all, closely, related, the"
5375,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.157894737,"the, to, isolated, in, from, of"
5376,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.157894737,"from, in, to, closely, related, the, of, is, bats"
5377,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.157894737,"available, sars-cov-2, is, a, that, and"
5378,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.157894737,"and, is, evidence, a, natural, origin"
5379,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.157894737,"that, natural, origin, and, evidence, is"
5380,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.157894737,"of, more, it, is, to, that, sars-cov-2, host,, and"
5381,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.157894737,"of, the, virus, and, betacoronavirus, coronavirus"
5382,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.157894737,"the, that, virus, to, of, and"
5383,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.157894737,"the, virus, and, of, sequence, identity"
5384,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.157894737,"the, virus, of, coronavirus, and, betacoronavirus"
5385,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",COVID-19 is a zoonotic virus,0.157894737,"is, virus, covid-19"
5386,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.157894737,"to, be, a, bats, and, the, pangolin, as, intermediate"
5387,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.157894737,"genomic, analysis, that, the, to, of"
5388,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.157894737,"analysis, that, sars-cov-2, the, of, to"
5389,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.157894737,"the, of, and, novel, coronavirus, has"
5390,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.157894737,"the, covid-19, to, bat, and, that"
5391,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.157894737,"of, the, that, revealed, and, novel"
5392,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.157894737,"and, bat, identity, to, the, of"
5393,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.157894737,"of, covid-19, virus, revealed, the, and"
5394,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.157894737,"that, from, the, seafood, and, animals"
5395,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.157894737,"to, started, the, seafood, market, in"
5396,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.157894737,"to, the, in, and, that, animals, a, outbreak, wuhan,"
5397,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","the close relation  

between SARS coronavirus and 2019-nCoV",0.157894737,"the, sars, and"
5398,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.157894737,"within, the, sequences, are, to, sars-cov"
5399,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.157894737,"and, revealed, that, the, novel, of"
5400,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.157894737,"the, that, sars-cov-2, with, of, and"
5401,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.157894737,"the, of, and, sars-cov-2, animal, humans"
5402,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.157894737,"the, bats, to, intermediate, hosts, of"
5403,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","Bats are natural hosts of many of the known  

coronaviruses",0.157894737,"are, the, of"
5404,The COVID-19 most likely developed from bat origin coronaviruses,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.157894737,"the, most, likely"
5405,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.157894737,"is, to, a, of, and, the"
5406,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.157894737,"the, was, in, that, a, of"
5407,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.157894737,"a, of, genome, at, the, in"
5408,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.157894737,"that, the, with, at, of, to"
5409,"Bats are natural hosts of many of the known  

coronaviruses","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.157894737,"are, of, the"
5410,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.157894737,"the, started, seafood, market, in, to"
5411,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.157894737,"the, of, in, to, isolated, from"
5412,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.157894737,"a, in, the, that, was, of"
5413,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.157894737,"bats, are, the, a, of, covs,"
5414,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.157894737,"sars-cov-2, of, the, recent, and, zoonotic, viruses, to, in"
5415,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.157894737,"to, the, as, a, of, spillover"
5416,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.157894737,"that, there, is, covid-19, wuhan, to"
5417,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.157894737,"is, and, it, more, that, of, sars-cov-2, to, host,"
5418,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.157894737,"bats, a, coronavirus, the, of, is, in, with, that, to, an, host"
5419,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.157894737,"found, that, sars-cov-2, sequences, to, pangolin, a, the, of"
5420,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.157894737,"of, in, that, sars-cov-2, a, with"
5421,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.157894737,"found, that, sars-cov-2, genome, a, of"
5422,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.157894737,"sars-cov-2, similar, to"
5423,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.157894737,"that, a, origin, of, been, by"
5424,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.157894737,"not, a, that, the, been, by"
5425,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.157894737,"of, phylogenetic, analysis, that, the, and"
5426,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.157894737,"of, the, and, that, sars-cov-2, group"
5427,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.157894737,"that, the, sars-cov-2, and, is, same"
5428,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.157894737,"and, sars-cov-2, in, to, bats, of"
5429,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.157894737,"sars-cov-2, at, the, of, sequence, with"
5430,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.157894737,"the, to, as, an, intermediate, host"
5431,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.157894737,"provide, evidence, and, that, the, of"
5432,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.157894737,"that, market, in, the, was, outbreak"
5433,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.157894737,"is, the, virus, zoonotic, of, to"
5434,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.157894737,"bat, and, species, to, the, of"
5435,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.157894737,"the, and, sars-cov-2, to, bat, in"
5436,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.157894737,"the, that, are, to, sars-cov-2, and"
5437,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.157894737,"to, date, that, sars-cov-2, the, and"
5438,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.157894737,"sars-cov-2, and, bat, coronaviruses, to, the"
5439,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.157894737,"viruses, closely, related, to, and, the"
5440,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.157894737,"in, the, sars, virus, were, to, and, closely, related"
5441,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.157894737,"the, species, to, of, bat, and"
5442,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.157894737,"the, same, are, in, of, southern"
5443,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.157894737,"the, genome, sars-cov-2, to, coronavirus, bat"
5444,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.157894737,"viruses, are, to, the, of, sars-cov-2"
5445,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.157894737,"sars-cov-2, are, also, to, the, of"
5446,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.157894737,"the, of, rbd, similar, to, that"
5447,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.157894737,"the, and, viruses, closely, related, to"
5448,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.157894737,"the, sars-cov-2, to, in, is, be"
5449,COVID-19 is a zoonotic virus,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.157894737,"covid-19, is, virus"
5450,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.157894737,"was, the, with, wuhan, pneumonia, seafood, market, a, of"
5451,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.157894737,"the, virus, sars, and, closely, related, to, were, in"
5452,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.157894737,"from, the, was, to, a, virus, that, as, and, human, adapted, sars, in, of, sample, taken, at, an"
5453,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.157894737,"in, the, of, as, an, sars, was, a, at, that, virus, taken, from, to, sample, human, and, adapted"
5454,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.157894737,"of, covid-19, cases, in, the, huanan, market, with, wuhan, by, early, january"
5455,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.157894737,"to, the, a, is, zoonotic, origin"
5456,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.157894737,"is, the, zoonotic, and, of, to"
5457,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.157894737,"evidence, a, natural, origin, and, is"
5458,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.157894737,"a, the, covid-19, is, of, and"
5459,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.157894737,"to, a, spillover, animal, and, the"
5460,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.157894737,"most, that, a, the, cause, sars-cov-2, pandemic, is, to"
5461,"with the first case being linked to  

a seafood market","expended to make the simple point 

that COVID-19 had a natural origin.",0.157894737,"the, to, a"
5462,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.157894737,"sars-cov-2, from, to, related, coronaviruses, bats"
5463,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.157894737,"the, bat, that, sequence, 96.2%, a"
5464,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.157894737,"the, that, bats, likely, hosts, for"
5465,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.157894737,"it, is, that, the, sars-cov-2, a"
5466,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.157894737,"the, of, similar, to, rbd, that"
5467,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.157894737,"that, the, sars-cov-2, very, similar, to"
5468,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.157894737,"this, that, in, the, virus, of"
5469,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","In the 

case of MERS, dromedaries were the principal host.",0.157894737,"the, in, of"
5470,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","In the 

case of MERS, dromedaries were the principal host.",0.157894737,"were, in, the"
5471,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.157894737,"more, than, genetic, bats, of, and"
5472,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.157894737,"bats, the, of, sars-cov, and, mers-cov"
5473,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.157894737,"analysis, covid-19, that, to, the, and"
5474,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",The COVID-19 most likely developed from bat origin coronaviruses,0.157894737,"the, bat, origin"
5475,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.157894737,"of, the, genomic, analysis, that, to"
5476,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",Bats are hosts of many coronaviruses,0.157894737,"of, are, bats"
5477,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",Bats are hosts of many coronaviruses,0.157894737,"of, coronaviruses, are"
5478,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.157894737,"been, that, the, of, most, by"
5479,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.157894737,"the, of, covid-19, to, that, most"
5480,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.157894737,"of, the, virus, revealed, covid-19, and"
5481,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.157894737,"the, analysis, that, covid-19, to, and"
5482,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.157894737,"that, the, outbreak, a, animals, in, wuhan,, to, and"
5483,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.157894737,"huanan, seafood, wholesale, in, the, of"
5484,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.157894737,"all, humans, closely, related, bats, the"
5485,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.157894737,"to, have, the, of, and, sars-cov, which, virus, masked, palm, civet, (paguma"
5486,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.157894737,"the, of, in, a, and, market"
5487,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.157894737,"patients, in, the, of, between, and"
5488,"In the 

case of MERS, dromedaries were the principal host.","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.157894737,"in, the, were"
5489,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.157894737,"from, or, in, the, may, have"
5490,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.157894737,"the, is, that, a, of, and"
5491,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.157894737,"the, covid-19, and, is, of, a"
5492,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.157894737,"this, that, the, of, and, is"
5493,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.157894737,"has, been, that, and, the, of, most, species, by"
5494,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.157894737,"that, sars-cov-2, has, with, bat, cov"
5495,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.157894737,"other, coronavirus, in, most, the, animal"
5496,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.157894737,"that, in, from, a, an, to"
5497,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.157894737,"is, that, the, most, likely, a"
5498,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.157894737,"that, natural, and, the, virus, of"
5499,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.157894737,"the, rbd, of, to, sars-cov-2, was"
5500,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.157894737,"evidence, that, natural, origin, and, is"
5501,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.157894737,"this, that, the, is, of, and"
5502,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.157894737,"the, likely, that, bats, hosts, for"
5503,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.157894737,"bats, are, a, for, as, the, is, that, to"
5504,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.157894737,"that, is, most, likely, bats, bat"
5505,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.157894737,"it, is, that, a, sars-cov-2, the"
5506,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.157894737,"the, very, similar, to, that, sars-cov-2"
5507,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.157894737,"that, a, the, is, most, likely"
5508,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.157894737,"the, of, that, and, to, bat"
5509,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.157894737,"phylogenetic, analysis, of, the, that, and"
5510,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.157894737,"a, in, the, genome, of, at"
5511,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.157894737,"the, of, sars-cov-2, with, that, and"
5512,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.157894737,"that, a, in, of, with, sars-cov-2"
5513,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.157894737,"of, the, that, and, sars-cov-2, group"
5514,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.157894737,"of, the, novel, coronavirus, has, and"
5515,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.157894737,"the, sars-cov-2, that, and, is, bat"
5516,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.157894737,"the, that, and, sars-cov-2, is, same"
5517,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.157894737,"has, with, bat, cov, that, sars-cov-2"
5518,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.157894737,"in, the, of, between, patients, and"
5519,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.157894737,"that, of, to, a, found, pangolin, sars-cov-2, sequences, the"
5520,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.157894737,"that, a, found, genome, of, sars-cov-2"
5521,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.157894737,"the, are, also, to, sars-cov-2, of"
5522,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.157894737,"also, a, origin, are, the, and"
5523,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.157894737,"sars-cov-2, the, with, bat-sl-cov-2, of, pangolin-cov"
5524,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.157894737,"that, the, of, evidence, and, provide"
5525,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.157894737,"studies, that, have, and, are, the"
5526,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.157894737,"bats, are, a, of, covs,, the"
5527,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.157894737,"the, of, sars-cov, and, mers-cov, bats"
5528,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.157894737,"the, in, of, that, this, virus"
5529,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.157894737,"and, that, natural, of, the, virus"
5530,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.157894737,"of, the, sars-cov-2, with, that, and"
5531,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.157894737,"sars-cov-2, and, similarity, to, the, of"
5532,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.157894737,"to, the, that, sars-cov-2, of, from"
5533,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.157894737,"rbd, of, sars-cov-2, was, to, the"
5534,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.157894737,"sars-cov-2, is, a, of, animal, the"
5535,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.157894737,"is, to, of, an, and, the"
5536,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.157894737,"are, also, and, a, the, origin"
5537,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.157894737,"similar, to, the, protein, of, sars-cov-2"
5538,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.157894737,"of, malayan, pangolins, (manis, highly, as"
5539,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.157894737,"the, pangolin, to, one, of, intermediate"
5540,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.157894737,"the, an, intermediate, host, as, to"
5541,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.157894737,"more, closely, related, to, the, than"
5542,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.157894737,"recent, sars-cov-2, to, the, viruses, in, zoonotic, and, of"
5543,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.157894737,"the, of, sars-cov-2, to, bat, identity"
5544,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.157894737,"and, the, identity, to, of, bat"
5545,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.157894737,"the, coronaviruses, to, sars-cov-2, bat, and"
5546,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.157894737,"the, sars-cov-2, of, and, similarity, to"
5547,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.157407407,"a, by, from, was, at, market, in, that, the, virus, is, closely, related, to, of, were, found"
5548,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.157407407,"in, the, of, from, found, that, at, market, virus, was, to, were, by, a, is, closely, related"
5549,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.157142857,"sars-cov-2, is, a, between, and, coronaviruses, bat, be, to, which, in"
5550,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.157142857,"in, the, of, virus, for, is, to, that, with, and, a"
5551,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.157142857,"in, the, a, at, that, virus, from, infected, humans, to, and"
5552,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.157142857,"between, sars-cov-2, and, which, to, be, a, is, in, bat, coronaviruses"
5553,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.157142857,"a, for, the, of, is, virus, and, in, with, that, to"
5554,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.157142857,"spread, and, it, to, for, by, the, of, sars-cov-2, may, infect"
5555,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.157142857,"december, the, of, was, a, at, taken, from, to, sample, and"
5556,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.157142857,"that, the, virus, in, and, to, humans, from, infected, at, a"
5557,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.157142857,"the, sample, was, taken, from, a, at, and, to, of, december"
5558,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.157142857,"it, to, this, was, not, the, of, that, have, been, in"
5559,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.157142857,"the, of, sars-cov-2, to, may, it, for, infect, and, spread, by"
5560,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.157142857,"the, was, not, to, have, this, it, that, been, in, of"
5561,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.156862745,"a, of, been, theories, by, that, have, origin"
5562,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.156862745,"the, site, of, and, amino, acid, insertion, sars-cov-2"
5563,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.156862745,"the, in, that, sars-cov-2, was, also, virus, t"
5564,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.156862745,"the, genome, sequence, of, that, was, to, bat"
5565,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.156862745,"the, sequence, that, sars-cov-2, was, to, ratg13, virus"
5566,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.156862745,"the, of, sars-cov-2, to, be, humans, and, between"
5567,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.156862745,"in, of, were, to, infected, origin, that, zoonotic"
5568,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.156862745,"sars-cov-2, is, a, sequence, from, high, to, coronavirus"
5569,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.156862745,"coronaviruses, to, are, sars-cov-2, bat, in, china, and"
5570,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.156862745,"sars-cov-2, from, a, bat, to, in, an, host"
5571,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.156862745,"a, two, coronaviruses,, are, to, sars-cov-2, at, the"
5572,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.156862745,"that, a, naturally, occurring, evidence, is, to, an"
5573,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.156862745,"that, is, evidence, a, naturally, occurring, an, to"
5574,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.156862745,"the, coronavirus, that, was, to, bat, as, and"
5575,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.156862745,"that, the, in, and, to, a, market, wuhan,"
5576,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.156862745,"the, a, huanan, market, and, to, of, with"
5577,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.156862745,"that, has, the, with, of, virus, and, to"
5578,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.156862745,"of, with, similar, to, and, pangolins, the, sars-cov-2"
5579,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.156862745,"a, virus, that, humans, through, infected, to, the"
5580,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.156862745,"is, sequence, and, be, to, that, may, bats"
5581,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.156862745,"in, the, protein, of, a, isolated, from, pangolin"
5582,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.156862745,"humans, through, it, is, that, be, and, sars-cov-2"
5583,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.156862745,"of, the, novel, coronavirus, and, with, sars-, human"
5584,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.156862745,"bats, to, be, the, of, sars-, cov-2,, intermediate"
5585,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.156862745,"and, novel, sars-, the, coronavirus, of, human, with"
5586,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.156862745,"was, that, the, genome, sequence, of, to, bat"
5587,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.156862745,"the, was, as, coronavirus, that, bat, and, to"
5588,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.156862745,"of, a, genome, sequence, from, bat, in, yunnan"
5589,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.156862745,"of, the, protein, in, isolated, from, a, pangolin"
5590,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.156862745,"sars-, cov-2,, to, the, bats, be, of, intermediate"
5591,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.156862745,"to, high, sequence, a, coronavirus, from, sars-cov-2, is"
5592,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.156862745,"is, that, and, bats, may, be, sequence, to"
5593,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.156862745,"virus, the, was, to, ratg13, sequence, that, sars-cov-2"
5594,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.156862745,"to, this, that, sars-cov-2, the, virus, but, of"
5595,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.156862745,"a, that, the, to, and, changes, in, sars-cov-2"
5596,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.156862745,"the, in, of, to, that, sars-cov-2, this, virus"
5597,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.156862745,"and, human, that, a, of, the, virus, is"
5598,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.156862745,"of, the, in, and, that, sars-cov-2, a, with"
5599,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.156862745,"this, the, in, that, more, for, sars-cov-2, than"
5600,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.156862745,"a, of, the, has, been, by, that, origin"
5601,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.156862745,"in, the, to, that, sars-cov-2, changes, and, a"
5602,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.156862745,"the, of, be, to, between, humans, and, sars-cov-2"
5603,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.156862745,"sars-cov-2, to, are, and, coronaviruses, in, bat, china"
5604,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.156862745,"a, are, at, two, to, coronaviruses,, the, sars-cov-2"
5605,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.156862745,"the, amino, acid, site, insertion, sars-cov-2, and, of"
5606,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.156862745,"is, humans, and, it, that, sars-cov-2, through, be"
5607,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.156862745,"the, of, to, with, a, and, huanan, market"
5608,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.156862745,"through, that, the, virus, to, humans, infected, a"
5609,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.156862745,"t, also, that, sars-cov-2, was, the, virus, in"
5610,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.156862745,"in, the, of, virus, to, that, sars-cov-2, this"
5611,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.156862745,"that, of, virus, to, and, the, intermediate, hosts"
5612,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.156862745,"a, that, the, covid-19, outbreak, of, and, animals"
5613,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.156862745,"the, of, and, that, animals, a, covid-19, outbreak"
5614,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.156862745,"that, theories, a, origin, of, have, been, by"
5615,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.156862745,"the, that, of, has, been, origin, by, a"
5616,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.156862745,"sars-cov-2, from, an, host, to, a, in, bat"
5617,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.156862745,"the, of, virus, is, that, human, and, a"
5618,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.156862745,"suggest, that, the, bats, pangolins, hosts, for, sars-cov-2"
5619,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.156862745,"et, al., (2020), by, a, of, the, sars-cov-2"
5620,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.156862745,"genome, a, sequence, of, from, bat, in, yunnan"
5621,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.156862745,"the, similarity, between, sars-cov-2, and, ratg13, is, which"
5622,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.156862745,"pangolins, similar, to, and, with, the, of, sars-cov-2"
5623,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.156862745,"that, the, virus, and, to, intermediate, hosts, of"
5624,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.156862745,"et, al., (2020), a, of, sars-cov-2, by, the"
5625,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.156862745,"that, sars-cov-2, the, with, of, virus, and, to"
5626,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.156862745,"to, recombination, the, of, by, a, virus, with"
5627,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.156862745,"in, the, of, that, sars-cov-2, with, and, a"
5628,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.156862745,"to, and, is, that, viruses, ratg13, in, bat"
5629,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.156862745,"in, the, for, more, than, that, sars-cov-2, this"
5630,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.156862745,"and, similarity, between, sars-cov-2, ratg13, which, is, the"
5631,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.156862745,"suggest, that, bats, pangolins, the, hosts, for, sars-cov-2"
5632,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.156862745,"this, the, of, that, sars-cov-2, to, but, virus"
5633,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.156862745,"by, a, recombination, of, virus, with, to, the"
5634,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.156862745,"of, infected, that, were, to, in, zoonotic, origin"
5635,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.156862745,"is, and, bat, ratg13, to, viruses, that, in"
5636,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.15625,"of, are, in, viruses, a"
5637,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.15625,"of, enormous, bat, coronaviruses, distributed"
5638,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.15625,"the, sars, in, from, bats"
5639,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.15625,"be, the, of, and, animal"
5640,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.15625,"similar, to, bat, and, sars-cov-2."
5641,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.15625,"of, sars-cov-2, and, to, sars-cov"
5642,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.15625,"genome, sars-cov-2, is, identical, to"
5643,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.15625,"of, in, bats, the, china"
5644,"An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.15625,"enormous, of, coronaviruses, bat, distributed"
5645,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.15625,"the, that, research, to, sars-cov-2"
5646,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.15625,"is, identical, to, sars-cov-2, genome"
5647,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.15625,"natural, origin, of, based, on"
5648,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.15625,"is, that, had, a, in"
5649,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.15625,"the, of, sars-cov-2, hosts, humans"
5650,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.15625,"a, coronavirus, the, to, of"
5651,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.15625,"and, to, an, the, of"
5652,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.15625,"sars-cov-2, isolated, from, to, the"
5653,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.15625,"considered, a, sars-cov-2, with, the"
5654,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.15625,"the, sars-cov, and, to, in"
5655,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.15625,"that, bat, in, of, sars-cov-2"
5656,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.15625,"is, that, the, sars-cov-2, bat"
5657,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.15625,"is, that, sars-cov-2, the, and"
5658,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.15625,"and, that, the, of, sars-cov-2"
5659,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.15625,"the, and, sars-cov-2, to, of"
5660,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.15625,"of, to, sars-cov-2, the, and"
5661,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.15625,"sars-cov-2, to, the, and, of"
5662,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.15625,"can, be, the, and, of"
5663,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","with the first case being linked to  

a seafood market",0.15625,"the, to, with, seafood, market"
5664,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.15625,"a, and, origin, the, in"
5665,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.15625,"a, in, and, which, the"
5666,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.15625,"in, the, originated, and, a"
5667,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.15625,"a, from, the, to, sars-cov-2"
5668,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.15625,"the, evidence, that, from, as"
5669,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.15625,"that, of, sars-cov-2, into, the"
5670,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.15625,"that, sars-cov-2, hypothesis, the, of"
5671,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.15625,"the, zoonotic, from, intermediate, host"
5672,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.15625,"the, closely, related, to, in"
5673,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.15625,"the, origin, and, a, in"
5674,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.15625,"the, of, is, with, and"
5675,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.15625,"lineage, at, the, huanan, was, of, from, a, by, al."
5676,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.15625,"the, to, in, animal, reservoirs"
5677,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.15625,"the, that, animal, reservoir, at"
5678,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.15625,"that, the, likely, sars-cov-2, than"
5679,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.15625,"a, is, that, in, had"
5680,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.15625,"wiv, a, that, sars-cov-2, in"
5681,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.15625,"are, the, virus, was, transmitted, from, to, a, market, in"
5682,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.15625,"is, that, the, virus, and"
5683,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.15625,"natural, and, was, in, host"
5684,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.15625,"natural, in, and, the, of"
5685,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.15625,"the, a, was, first, and"
5686,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.15625,"the, first, was, that, bat"
5687,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.15625,"to, the, sars-cov-2, a, from"
5688,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.15625,"a, to, has, sars-cov-2, the"
5689,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.15625,"sars-cov-2, pangolin, similarity, to, the"
5690,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.15625,"ratg13, has, the, with, sars-cov-2"
5691,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.15625,"although, ratg13, the, bat, coronavirus"
5692,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.15625,"a, the, has, to, sars-cov-2"
5693,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.15625,"sars-cov-2, a, virus, the, and"
5694,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.15625,"analysis, that, the, sars-cov-2, a"
5695,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.15625,"in, a, to, the, are, virus, was, transmitted, from, market"
5696,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.15625,"the, virus, from, market, to"
5697,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.15625,"that, the, more, likely, origin"
5698,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.15625,"in, to, the, animal, reservoirs"
5699,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.15625,"the, that, animal, origin, is"
5700,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.15625,"zoonotic, to, the, that, and"
5701,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.15625,"and, to, bats, the, of"
5702,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.15625,"the, sars-cov-2, to, be, bat"
5703,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.15625,"bat, has, genome, of, sars-cov-2"
5704,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.15625,"of, sars-cov-2, has, been, the"
5705,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.15625,"that, are, the, reservoir, of"
5706,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.15625,"it, that, the, of, bat"
5707,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.15625,"are, viruses, in, a, of"
5708,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.15625,"human, that, a, virus, is"
5709,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.15625,"to, the, isolated, from, sars-cov-2"
5710,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.15625,"the, sars, from, in, bats"
5711,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.15625,"the, are, in, and, asia,"
5712,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.15625,"the, sars-cov-2, that, and, is"
5713,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.15625,"the, that, and, sars-cov-2, is"
5714,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.15625,"coronavirus, the, that, to, of"
5715,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.15625,"the, with, genome, to, of"
5716,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.15625,"that, the, zoonotic, and, to"
5717,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.15625,"the, of, sars-cov-2, coronaviruses, to"
5718,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.15625,"the, of, sars, and, mers"
5719,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.15625,"are, and, transmitted, direct, contact."
5720,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.15625,"in, that, sars-cov-2, this, virus"
5721,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.15625,"the, of, sars-cov-2, with, and"
5722,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.15625,"of, sars-cov-2, and, the, humans"
5723,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Bats are natural hosts of many of the known  

coronaviruses",0.15625,"bats, are, the, known, of"
5724,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.15625,"to, a, of, coronavirus, the"
5725,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.15625,"to, the, with, a, coronavirus"
5726,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.15625,"that, the, of, coronavirus, to"
5727,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.15625,"with, genome, to, the, of"
5728,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.15625,"of, the, in, that, was"
5729,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.15625,"a, of, sars-, cov-2, was"
5730,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.15625,"the, of, may, be, a"
5731,"This suggests that the BANAL series may be able to directly infect  

humans.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.15625,"that, the, be, to, directly"
5732,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.15625,"of, sars-cov-2, that, the, a"
5733,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.15625,"sars-cov-2, to, of, and, the"
5734,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.15625,"the, and, bats, of, to"
5735,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.15625,"et, the, of, to, sars-cov-2"
5736,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.15625,"the, animal, reservoir, at, that"
5737,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.15625,"the, that, animal, of, origin"
5738,"S1/S2 cleavage sites of coronaviruses are frequently modi- 

fied by insertions or deletions (indels) during evolution","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.15625,"cleavage, sites, of, coronaviruses, or"
5739,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.15625,"the, sars-cov-2, and, origin, of"
5740,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.15625,"the, to, coronavirus, was, a"
5741,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K",0.15625,"to, viruses, in, human, than"
5742,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.15625,"a, bat, in, has, of"
5743,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.15625,"has, a, and, in, zoonotic"
5744,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.15625,"of, has, been, the, a"
5745,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.15625,"the, with, a, sars-cov-2, considered"
5746,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.15625,"the, genetic, similarity, sars-cov-2, with"
5747,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.15625,"the, may, be, a, of"
5748,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.15625,"research, that, sars-cov-2, to, the"
5749,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.15625,"that, sars-cov-2, in, of, bat"
5750,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.15625,"genome, of, sars-cov-2, has, bat"
5751,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.15625,"of, a, has, in, bat"
5752,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.15625,"of, that, sars-cov-2, a, virus"
5753,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.15625,"that, sars-cov-2, is, to, the"
5754,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.15625,"the, virus, from, to, market"
5755,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.15625,"the, is, that, origin, animal"
5756,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.15625,"the, that, animal, origin, of"
5757,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.15625,"the, that, sars-, cov-2, is"
5758,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.15625,"is, the, and, pangolin-cov, sars-cov-2"
5759,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.15625,"sars-cov-2, et, to, the, of"
5760,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.15625,"in, to, of, sars-cov-2, the"
5761,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.15625,"the, of, sars-cov-2, and, humans"
5762,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.15625,"the, ratg13, has, with, sars-cov-2"
5763,"This suggests that the BANAL series may be able to directly infect  

humans.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.15625,"that, the, able, to, infect"
5764,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.15625,"sars-cov-2, was, that, to, and"
5765,"with the first case being linked to  

a seafood market","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.15625,"with, the, to, seafood, market"
5766,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.15625,"and, the, sars, mers, of"
5767,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.15625,"in, the, are, asia,, and"
5768,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.15625,"all, that, are, to, in"
5769,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.15625,"in, related, the, closely, to"
5770,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.15625,"viruses, in, and, to, the"
5771,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.15625,"to, of, an, and, the"
5772,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.15625,"bat, the, of, and, an"
5773,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.15625,"experiments, to, that, human, than"
5774,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","This suggests that the BANAL series may be able to directly infect  

humans.",0.15625,"be, directly, to, the, that"
5775,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","This suggests that the BANAL series may be able to directly infect  

humans.",0.15625,"the, to, that, this, humans."
5776,"In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.15625,"in, to, viruses, than, human"
5777,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.15625,"experiments, that, to, human, than"
5778,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.15625,"the, furin, cleavage, site, of"
5779,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.15625,"of, the, furin, cleavage, site"
5780,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.15625,"is, the, most, sars-cov-2, to"
5781,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.15625,"of, lineage, a, at, the, huanan, was, by, al., from"
5782,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.15625,"and, from, in, were, found, to, related, that, bats, sars-cov-2"
5783,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.15625,"the, and, which, a, in"
5784,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.15625,"the, and, viruses, to, in"
5785,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.15625,"in, was, natural, host, and"
5786,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.15625,"a, zoonotic, and, has, in"
5787,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.15625,"that, wiv, sars-cov-2, a, in"
5788,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.15625,"of, sars-cov-like, it, is, that"
5789,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.15625,"the, sars-, cov-2, that, is"
5790,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.15625,"the, is, that, sars-, cov-2"
5791,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.15625,"it, is, that, of, sars-cov-like"
5792,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.15625,"that, sars-cov-2, the, of, into"
5793,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.15625,"sars-cov-2, virus, that, in, this"
5794,"This suggests that the BANAL series may be able to directly infect  

humans.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.15625,"this, that, the, to, humans."
5795,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.15625,"the, covid-19, to, in, seafood"
5796,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.15625,"and, are, transmitted, direct, contact."
5797,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.15625,"to, that, are, all, in"
5798,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.15625,"the, covid-19, in, to, seafood"
5799,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.15625,"in, the, that, was, of"
5800,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.15625,"in, was, that, of, the"
5801,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.15625,"bat, similar, to, and, sars-cov-2."
5802,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.15625,"the, bats, in, of, china"
5803,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.15625,"the, first, and, was, a"
5804,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.15625,"a, of, in, and, the"
5805,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.15625,"in, the, between, and, of"
5806,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.15625,"that, a, virus, of, sars-cov-2"
5807,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.15625,"and, the, virus, for, of"
5808,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.15625,"based, on, natural, of, origin"
5809,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.15625,"a, was, of, sars-, cov-2"
5810,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.15625,"the, of, sars-cov-2, has, been"
5811,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.15625,"of, the, that, sars-cov-2, a"
5812,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.15625,"the, of, a, has, been"
5813,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.15625,"sars-cov-2, to, bat, be, the"
5814,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.15625,"virus, that, is, a, human"
5815,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.15625,"that, was, to, and, sars-cov-2"
5816,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.15625,"that, sars-cov-2, and, ratg13, viruses"
5817,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.15625,"that, sars-cov-2, are, to, and"
5818,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.15625,"evidence, the, that, as, from"
5819,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.15625,"of, the, sars-cov-2, to, coronaviruses"
5820,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.15625,"sars-cov-2, genetic, similarity, with, the"
5821,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.15625,"the, that, sars-cov-2, is, bat"
5822,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.15625,"the, that, sars-cov-2, is, a"
5823,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.15625,"is, the, most, to, sars-cov-2"
5824,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.15625,"again, the, bat, cov, pangolin"
5825,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.15625,"pangolin, cov, the, origin, of"
5826,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.15625,"this, that, sars-cov-2, in, bats"
5827,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.15625,"again, the, bat, pangolin, cov"
5828,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.15625,"the, sars-cov-2, likely, than, that"
5829,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.15625,"the, origin, more, likely, that"
5830,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.15625,"the, origin, of, sars-cov-2, and"
5831,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.15625,"sars-cov-2, viruses, that, ratg13, and"
5832,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.15625,"this, in, that, bats, sars-cov-2"
5833,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.15625,"the, pangolin, origin, of, cov"
5834,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.15625,"sars-cov, and, sars-cov-2, to, of"
5835,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.15625,"sars-cov-2, the, of, with, sars-cov"
5836,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.15625,"of, the, and, sars-cov-2, is"
5837,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.15625,"is, with, and, of, the"
5838,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.15625,"of, sars-cov-2, the, pangolin-cov, and"
5839,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.15625,"of, the, sars-cov-2, with, and"
5840,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.15625,"sars-cov-2, and, identity, the, of"
5841,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.15625,"the, of, sars-cov-2, that, and"
5842,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.15625,"the, and, a, originated, in"
5843,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.15625,"that, the, of, are, reservoir"
5844,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.15625,"the, sars-cov-2, with, and, is"
5845,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.15625,"the, pangolin-cov, and, sars-cov-2, is"
5846,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.15625,"in, to, sars-cov-2, and, the"
5847,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.15625,"the, to, and, in, sars-cov-2"
5848,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.15625,"sars-cov-2, are, to, and, the"
5849,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.15625,"in, the, of, natural, and"
5850,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.15625,"for, and, the, of, virus"
5851,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.15625,"the, of, and, can, be"
5852,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.15625,"be, between, the, and, an"
5853,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.15625,"that, sars-cov-2, to, from, bat-sl-cov-2"
5854,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.15625,"the, first, bat, that, was"
5855,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.15625,"bat-sl-cov-2, to, that, sars-cov-2, from"
5856,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.15625,"of, and, be, the, animal"
5857,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.15625,"bat, and, an, the, of"
5858,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.15625,"a, sars-cov-2, the, and, virus"
5859,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.15625,"be, the, between, and, an"
5860,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.15625,"the, of, to, sars-cov-2, in"
5861,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.15625,"that, were, related, to, sars-cov-2, found, in, bats, and, from"
5862,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.15625,"although, the, ratg13, coronavirus, bat"
5863,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.15625,"the, pangolin, to, similarity, sars-cov-2"
5864,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.15625,"the, identity, of, sars-cov-2, and"
5865,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.15625,"a, analysis, that, sars-cov-2, the"
5866,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.15625,"a, analysis, the, sars-cov-2, that"
5867,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.155844156,"spread, from, multiple, to, the, of, that, sars-cov-2, may, have, in, a"
5868,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.155844156,"from, in, spread, the, of, multiple, that, a, sars-cov-2, may, have, to"
5869,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.155555556,"the, of, a, sarbecovirus, from, pangolins, and"
5870,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.155555556,"sars-cov-2, to, very, in, bat, pangolin, which"
5871,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.155555556,"the, genetic, that, is, from, any, virus"
5872,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.155555556,"to, virus, and, genome, was, the, sars-cov-2"
5873,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.155555556,"the, sequence, showed, identity, to, and, cov"
5874,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.155555556,"with, the, of, genome, sars-like, covs, and"
5875,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.155555556,"in, is, with, sars-cov-2, the, sequence, of"
5876,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.155555556,"sequence, identity, sars-cov-2, sars-cov, with, the, of"
5877,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.155555556,"the, is, origin, a, high, homology, from"
5878,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.155555556,"pangolins, to, humans, from, the, of, sars-cov-2"
5879,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.155555556,"to, sars-cov-2, found, in, bats, pangolins, from"
5880,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.155555556,"the, in, bats, to, humans, through, of"
5881,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.155555556,"this, sars-cov-2, bat, to, the, viruses, that"
5882,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.155555556,"the, of, to, sars-cov-2, at, that, mutations"
5883,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.155555556,"through, that, the, and, to, animals, market"
5884,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.155555556,"of, from, two, and, were, in, sars-cov-2"
5885,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.155555556,"a, in, the, spillover, events, that, to"
5886,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.155555556,"from, as, raccoon, dogs,, to, this, was, for, the, of, that, have, in, a"
5887,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.155555556,"virus, the, was, to, bat, and, that"
5888,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.155555556,"of, the, in, and, that, a, with"
5889,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.155555556,"the, in, of, to, that, this, virus"
5890,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.155555556,"to, is, virus, that, from, and, the"
5891,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.155555556,"the, virus, is, to, that, and, from"
5892,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.155555556,"the, sars-cov-2, to, humans, from, pangolins, of"
5893,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.155555556,"genetic, that, the, virus, and, to, a"
5894,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.155555556,"animal, and, the, of, which, is, transmitted"
5895,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.155555556,"of, sars-cov-2, was, shown, to, which, the"
5896,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.155555556,"through, the, market, animals, that, to, and"
5897,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.155555556,"a, genetic, to, that, the, and, virus"
5898,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.155555556,"is, the, virus, and, bats, of, to"
5899,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.155555556,"of, evidence, that, the, is, a, as"
5900,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.155555556,"the, virus, of, to, identity, that, and"
5901,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.155555556,"to, is, of, the, virus, bats, and"
5902,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.155555556,"that, may, of, virus, to, and, the"
5903,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.155555556,"to, be, the, sars-, while, may, intermediate"
5904,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.155555556,"the, of, to, sars-cov-2, has, been, human"
5905,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.155555556,"the, virus, for, it, is, to, a"
5906,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.155555556,"evidence, that, is, origin, a, animal, or"
5907,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.155555556,"the, virus, of, to, that, coronavirus, and"
5908,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.155555556,"genome, sequence, identity, with, bat, ratg13,, and"
5909,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.155555556,"the, of, and, is, animal, which, transmitted"
5910,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.155555556,"sars-cov-2, the, of, sequence, identity, with, sars-cov"
5911,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.155555556,"with, the, of, a, genome, two, and"
5912,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.155555556,"to, the, sars-, while, may, be, intermediate"
5913,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.155555556,"are, to, the, bats, pangolins, be, hosts"
5914,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.155555556,"the, horseshoe, to, of, sars-cov-2, bat, (rhinolophus"
5915,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.155555556,"et, a, bat, of, sars-cov-2, the, in"
5916,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.155555556,"a, of, and, the, from, sarbecovirus, pangolins"
5917,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.155555556,"and, a, of, between, sars-cov-2, ratg13, the"
5918,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.155555556,"in, the, of, has, been, and, a"
5919,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.155555556,"with, the, and, sars-like, covs, of, genome"
5920,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.155555556,"a, of, the, genome, with, and, two"
5921,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.155555556,"virus, genome, the, was, to, and, sars-cov-2"
5922,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.155555556,"the, of, sars-cov-2, has, been, to, human"
5923,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.155555556,"a, virus, to, for, the, it, is"
5924,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.155555556,"the, of, a, and, has, been, in"
5925,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.155555556,"of, the, that, sars-cov-2, is, a, virus"
5926,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.155555556,"the, of, sars-cov-2, is, with, and, to"
5927,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.155555556,"for, and, that, in, the, of, sars-cov-2"
5928,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.155555556,"were, two, of, sars-cov-2, from, in, and"
5929,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.155555556,"in, a, of, sars-cov-2, found, with, that"
5930,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.155555556,"et, al., (2020), of, to, the, sars-cov-2"
5931,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.155555556,"from, in, the, of, and, those, reported"
5932,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.155555556,"serve, as, the, animal, for, of, and"
5933,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.155555556,"therefore,, sars-cov-2, is, to, in, the, or"
5934,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.155555556,"the, of, sars-cov-2, is, a, virus, in"
5935,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.155555556,"of, animal, and, the, serve, as, for"
5936,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.155555556,"the, to, sars-cov-2, of, horseshoe, bat, (rhinolophus"
5937,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.155555556,"in, this, the, between, and, of, bat"
5938,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.155555556,"the, that, in, a, to, spillover, events"
5939,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.155555556,"the, at, this, that, a, in, animal"
5940,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.155555556,"is, that, a, sars-cov-2, into, the, through"
5941,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.155555556,"that, a, natural, the, virus, is, most"
5942,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.155555556,"found, that, sars-cov-2, to, a, on, the"
5943,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.155555556,"sars-cov-2, to, from, bats, pangolins, in, found"
5944,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.155555556,"bats, and, pangolins, from, in, china,, china"
5945,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.155555556,"this, a, strong, that, the, is, of"
5946,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.155555556,"is, that, from, the, virus, genetic, any"
5947,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.155555556,"bat, is, the, that, bats, hosts, for"
5948,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.155555556,"ratg13,, which, in, rhinolophus, affinis, the, sars-cov-2,"
5949,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.155555556,"sars-cov-2, is, a, that, into, through, the"
5950,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.155555556,"this, of, to, the, in, that, virus"
5951,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.155555556,"this, we, sars-cov-2, to, the, that, in"
5952,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.155555556,"the, to, cov, and, showed, sequence, identity"
5953,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.155555556,"the, high, homology, a, from, is, origin"
5954,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.155555556,"is, evidence, that, the, as, of, a"
5955,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.155555556,"evidence, that, a, animal, origin, is, or"
5956,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.155555556,"the, amino, acid, sequence, of, receptor, domain"
5957,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.155555556,"the, to, humans, bats, through, in, of"
5958,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.155555556,"with, the, sars-cov-2, is, in, of, sequence"
5959,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.155555556,"the, amino, acid, sequence, of, domain, receptor"
5960,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.155555556,"in, bats, china,, and, pangolins, china, from"
5961,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.155555556,"the, of, is, a, that, this, strong"
5962,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.155555556,"genome, sequence, and, with, bat, ratg13,, identity"
5963,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.155555556,"that, sars-cov-2, a, with, bat, cov, genome"
5964,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.155555556,"the, of, virus, is, that, sars-cov-2, a"
5965,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.155555556,"is, that, sars-cov-2, a, the, of, virus"
5966,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.155555556,"in, a, of, to, have, the, that, was, this, from, raccoon, dogs,, for, as"
5967,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.155555556,"is, a, natural, virus, that, the, most"
5968,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.155555556,"the, of, shown, sars-cov-2, which, was, to"
5969,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.155555556,"suggest, the, bat, of, virus, and, covs"
5970,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.155555556,"the, sars-cov-2, in, of, a, bat, et"
5971,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.155555556,"the, of, sars-cov-2, a, between, and, ratg13"
5972,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.155555556,"for, between, and, in, the, of, sars-cov-2"
5973,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.155555556,"that, the, virus, and, may, of, to"
5974,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.155555556,"et, al., (2020), the, of, to, sars-cov-2"
5975,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.155555556,"that, the, of, in, with, a, and"
5976,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.155555556,"bats, are, to, be, the, hosts, pangolins"
5977,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.155555556,"the, bat, is, that, bats, hosts, for"
5978,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.155555556,"viruses, to, bat, that, the, sars-cov-2, this"
5979,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.155555556,"the, in, to, that, sars-cov-2, we, this"
5980,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.155555556,"sars-cov-2, to, bat, pangolin, in, which, very"
5981,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.155555556,"therefore,, the, is, sars-cov-2, or, to, in"
5982,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.155555556,"the, is, sars-cov-2, that, pangolin, cov, which"
5983,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.155555556,"in, from, of, reported, and, the, those"
5984,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.155555556,"of, suggest, the, virus, bat, covs, and"
5985,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.155555556,"sars-cov-2, a, that, found, on, to, the"
5986,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.155555556,"the, of, to, sars-cov-2, that, pangolin, cov"
5987,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.155555556,"genome, with, bat, cov, that, sars-cov-2, a"
5988,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.155555556,"the, of, is, to, sars-cov-2, with, and"
5989,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.155555556,"in, the, of, for, that, sars-cov-2, and"
5990,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.155555556,"and, of, between, sars-cov-2, in, the, for"
5991,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.155555556,"this, of, and, bat, between, in, the"
5992,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.155555556,"to, that, sars-cov-2, the, bats, of, sars-cov-2,"
5993,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.155555556,"at, mutations, to, that, the, of, sars-cov-2"
5994,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.155555556,"that, the, sars-cov-2, cov, pangolin, is, which"
5995,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.155555556,"that, sars-cov-2, to, pangolin, cov, the, of"
5996,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.155555556,"the, of, to, sars-cov-2,, that, sars-cov-2, bats"
5997,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.155555556,"the, is, of, sars-cov-2, a, virus, in"
5998,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.155555556,"animal, at, a, this, in, the, that"
5999,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.155555556,"that, a, found, in, of, with, sars-cov-2"
6000,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.155555556,"ratg13,, rhinolophus, affinis, sars-cov-2,, in, the, which"
6001,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.155172414,"a, is, virus, thus, and, with, properties, that, their"
6002,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.155172414,"properties, with, their, and, is, thus, a, virus, that"
6003,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.155172414,"in, can, be, that, the, recombination, and, an, of"
6004,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.155172414,"between, and, likely, sars-cov-2, to, an, host,, animal, species"
6005,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.155172414,"in, a, of, patients, were, infected, with, that, may"
6006,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.155172414,"to, that, the, sarbecovirus, of, betacoronavirus, and, have, sars-cov-2"
6007,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.155172414,"in, the, of, sars, outbreak, from, to, closely, related"
6008,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.155172414,"sars-cov-2, an, animal, to, likely, host,, between, and, species"
6009,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.155172414,"in, the, of, virus, sars-cov-2, has, with, and, a"
6010,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.155172414,"pangolin, to, sars-cov-2, in, the, rbd, this, that, of"
6011,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.155172414,"has, a, sars-cov-2, and, with, the, of, virus, in"
6012,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.155172414,"been, and, in, to, the, of, sars-cov-2, has, is"
6013,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.155172414,"an, intermediate, host, species, bats, humans, found, in, the"
6014,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.155172414,"to, that, natural, emergence, the, of, and, is, be"
6015,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.155172414,"the, sars-cov-2, to, may, be, for, humans, and, between"
6016,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.155172414,"the, ability, to, may, obtained, through, it, infect, and"
6017,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.155172414,"and, may, be, for, sars-cov-2, to, humans, the, between"
6018,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.155172414,"it, the, and, to, may, obtained, ability, infect, through"
6019,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.155172414,"the, coronaviruses, to, date, that, sars-cov-2, in, and, southeast"
6020,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.155172414,"to, date, sars-cov-2, in, the, southeast, and, that, coronaviruses"
6021,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.155172414,"by, the, virus, is, closely, related, to, group, of"
6022,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.155172414,"the, of, covid-19, were, associated, with, huanan, seafood, wuhan"
6023,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.155172414,"the, of, with, huanan, seafood, market, and, sample, at"
6024,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.155172414,"the, of, sars, outbreak, in, closely, related, to, from"
6025,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.155172414,"the, sample, at, huanan, seafood, market, and, of, with"
6026,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.155172414,"from, in, china, that, related, to, were, found, bats"
6027,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.155172414,"this, in, the, of, that, sars-cov-2, to, rbd, pangolin"
6028,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.155172414,"seafood, in, wuhan, that, the, virus, to, of, bats"
6029,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.155172414,"of, the, covid-19, were, wuhan, associated, with, huanan, seafood"
6030,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.155172414,"bats, humans, an, intermediate, host, found, in, species, the"
6031,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.155172414,"in, the, of, is, to, sars-cov-2, has, been, and"
6032,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.155172414,"and, the, of, to, be, that, emergence, is, natural"
6033,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.155172414,"the, group, of, closely, related, virus, to, by, is"
6034,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.155172414,"that, were, related, to, found, in, bats, china, from"
6035,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.155172414,"that, the, virus, in, bats, to, wuhan, seafood, of"
6036,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.155172414,"have, the, sars-cov-2, and, betacoronavirus, of, sarbecovirus, to, that"
6037,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.155172414,"the, recombination, of, can, and, be, in, that, an"
6038,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.155172414,"that, patients, infected, with, in, may, were, a, of"
6039,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.154929577,"sars-cov, and, it, to, was, for, by, the, that, sars-cov-2, a"
6040,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.154929577,"a, it, was, that, the, sars-cov-2, and, for, to, by, sars-cov"
6041,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.154761905,"in, to, the, for, discovered, and, sars, viruses, were, closely, related, other, virus"
6042,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.154761905,"the, virus, for, sars, and, other, viruses, closely, related, to, were, discovered, in"
6043,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.154761905,"a, january, 2020, positive, samples, collected, on, and, to, of, in, the, huanan"
6044,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.154761905,"and, to, samples, the, huanan, in, of, january, on, 2020, collected, a, positive"
6045,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.154639175,"on, in, the, and, january, of, positive, environmental, samples, collected, 2020, to, huanan, from, market"
6046,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.154639175,"and, from, to, environmental, samples, the, huanan, market, in, of, january, on, 2020, collected, positive"
6047,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.154545455,"the, live, are, to, in, a, for, of, as, mammals, is, likely, was, that, virus, were, market"
6048,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.154545455,"in, a, of, to, the, are, likely, virus, that, was, is, mammals, were, live, market, for, as"
6049,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.153846154,"bat, species, an, of"
6050,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.153846154,"the, asia,, africa,, middle, east,, and"
6051,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.153846154,"the, and, are, of, distributed, to"
6052,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.153846154,"bats, and, are, the, of, species"
6053,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.153846154,"animal, are, known, and, the, to"
6054,hese close genetic relations suggest that they all have their ecological origin in bat populations,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.153846154,"genetic, have, in, bat"
6055,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.153846154,"to, sars-cov-2, in, bats, china,, and"
6056,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.153846154,"in, bats, and, to, china,, of"
6057,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.153846154,"from, species, of, bats, were, and"
6058,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.153846154,"the, to, many, sars-like, and, sars"
6059,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.153846154,"sequences, are, similar, to, and, the"
6060,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.153846154,"is, a, coronavirus, and"
6061,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.153846154,"also, in, the, of"
6062,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.153846154,"in, the, emergence, of"
6063,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.153846154,"a, other, coronaviruses, to, recombination, in, sars-cov-2, the, bat, and"
6064,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.153846154,"genetic, and, that, a, virus, is"
6065,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.153846154,"of, distributed, and, are, to, the"
6066,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.153846154,"all, to, are, coronaviruses, bat, the"
6067,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.153846154,"that, sars-cov-2, have, natural, the, genome"
6068,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.153846154,"the, as, that, with, bat, to"
6069,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.153846154,"that, the, of, genome, a, bat"
6070,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.153846154,"ats, the, are, and"
6071,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.153846154,"the, natural, of, viruses"
6072,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.153846154,"ats, the, of, including"
6073,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.153846154,"the, viruses, of, and"
6074,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.153846154,"closer, to, bat, the, of, sars-cov-2"
6075,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.153846154,"in, of, to, sars-cov-2, and, the"
6076,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.153846154,"of, the, in, and, sars-cov-2, with"
6077,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.153846154,"sars-cov-2, genome, to, and, the, of"
6078,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.153846154,"are, to, sars-cov-2, of"
6079,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.153846154,"of, are, similar, to"
6080,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.153846154,"the, to, be, of, between, and"
6081,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.153846154,"have, the, between, sars-cov-2, and, of, to, that"
6082,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.153846154,"the, of, has, a, human, as"
6083,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.153846154,"the, reservoirs, and, other, have, been"
6084,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.153846154,"a, that, the, virus, was, had"
6085,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.153846154,"the, to, that, virus, in, and"
6086,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.153846154,"of, the, in, pangolins, (manis, javanica)"
6087,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.153846154,"the, of, and, has, been, in"
6088,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.153846154,"is, that, the, zoonotic, of, to"
6089,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.153846154,"this, that, the, covid-19, is, of"
6090,"Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.153846154,"is, a, and, coronavirus"
6091,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.153846154,"the, sars-cov-2, to, of, is, be"
6092,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.153846154,"the, to, sars-cov-2, an, of, a"
6093,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.153846154,"the, sars-cov-2, to, a, and, coronavirus"
6094,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.153846154,"bats, of, and, species, are, the"
6095,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.153846154,"the, and, bats, of"
6096,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.153846154,"natural, virus, that, into, to, cause, the, for"
6097,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.153846154,"is, to, at, the, in, wuhan"
6098,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.153846154,"detected, in, yunnan, was, to, the"
6099,The FCS of SARS-CoV-2 was not bioengineered—full stop.,zoonotic origins of SARS-CoV-2 by natural evolution,0.153846154,"of, sars-cov-2"
6100,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.153846154,"with, sars-cov-2, from, zoonotic"
6101,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.153846154,"the, to, sars-cov-2, isolated, from, a"
6102,"a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.153846154,"a, coronavirus, with, sars-cov-2"
6103,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.153846154,"the, from, sars-cov-2, to, a, coronavirus"
6104,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.153846154,"is, sars-cov-2, bat, the, that, in"
6105,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.153846154,"in, the, of, is, sars-cov-2, that"
6106,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.153846154,"that, sars-cov-2, is, to, bat, the"
6107,"According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.153846154,"to, sars-cov, is, bat"
6108,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.153846154,"the, to, of, sars-cov-2, bat, and"
6109,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.153846154,"that, bats, are, for"
6110,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","civet cats and raccoon dogs  

are the intermediate hosts",0.153846154,"hosts, and, are, the"
6111,Bats are hosts of many coronaviruses,"civet cats and raccoon dogs  

are the intermediate hosts",0.153846154,"are, hosts"
6112,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","civet cats and raccoon dogs  

are the intermediate hosts",0.153846154,"are, the, hosts, and"
6113,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.153846154,"the, was, a, coronavirus, that, with, and, to"
6114,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.153846154,"the, of, sars-cov-2, to, be, and"
6115,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.153846154,"to, sars-cov-2, the, bats, be, of"
6116,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","with the first case being linked to  

a seafood market",0.153846154,"seafood, market, the, first"
6117,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.153846154,"sars-cov-2, is, to, be, of, the"
6118,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.153846154,"is, the, bats, be, of, to"
6119,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.153846154,"from, bats, to, be, the, of"
6120,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.153846154,"a, the, that, had, virus, was"
6121,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.153846154,"virus, had, been, by, was, the"
6122,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.153846154,"in, an, from, species, to, sars-cov-2, and, several"
6123,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.153846154,"from, of, to, sars-cov-2, the, humans"
6124,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.153846154,"that, a, of, sars-cov-2, into, the"
6125,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.153846154,"that, a, natural, origin, of, the"
6126,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.153846154,"have, that, sars-cov-2, genome, the, natural"
6127,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.153846154,"coronavirus, the, that, was, of, at"
6128,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.153846154,"the, that, sars-cov-2, of"
6129,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.153846154,"with, from, sars-cov-2, zoonotic"
6130,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.153846154,"the, sars-cov-2, closer, to, bat, of"
6131,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.153846154,"the, that, are, to, sars-cov-2, of"
6132,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.153846154,"this, a, of, lineage, at, the"
6133,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.153846154,"a, of, the, sars-cov-2, that, two"
6134,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.153846154,"are, to, that, the, of, sars-cov-2"
6135,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.153846154,"of, the, to, huanan, and, that"
6136,"Bats are natural hosts of many of the known  

coronaviruses","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.153846154,"are, of, the, known"
6137,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.153846154,"of, to, sars-cov-2, and, the, infection"
6138,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.153846154,"a, study, that, the, to, in"
6139,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.153846154,"the, two, in, show, that, a"
6140,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.153846154,"a, at, the, of, this, lineage"
6141,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.153846154,"of, in, the, huanan, market, with"
6142,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.153846154,"huanan, in, the, 2019, and, of"
6143,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.153846154,"and, in, at, a, market, 2019"
6144,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.153846154,"the, of, in, market, this, at"
6145,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.153846154,"and, a, origin, of, the, is"
6146,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.153846154,"of, the, in, and, a, with"
6147,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.153846154,"the, huanan, that, to, and, of"
6148,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.153846154,"the, covid-19, to, and, that, was"
6149,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.153846154,"that, sars-cov-2, not, from, to, it, in, an"
6150,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.153846154,"there, is, that, or"
6151,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.153846154,"a, in, the, genome, that, to"
6152,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.153846154,"about, the, origins, of, to, that, most, scientists"
6153,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.153846154,"of, that, is, most, to, the, and, was"
6154,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.153846154,"that, to, with, bat, as, the"
6155,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.153846154,"the, a, coronavirus, was, that, to, and, with"
6156,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.153846154,"and, the, virus, was, to, a"
6157,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.153846154,"a, the, has, coronavirus, similarity, with"
6158,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.153846154,"the, virus, is, that, and, from"
6159,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.153846154,"is, virus, that, from, and, the"
6160,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.153846154,"is, from, to, human"
6161,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.153846154,"a, that, the, was, to, and"
6162,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.153846154,"a, that, the, to, bat, and"
6163,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.153846154,"the, to, be, intermediate"
6164,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.153846154,"the, of, covid-19, cases, with, huanan, market, in"
6165,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.153846154,"that, from, the, and, virus, is"
6166,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.153846154,"to, is, of, the, virus, which, has, and"
6167,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.153846154,"of, the, that, coronavirus, is, to"
6168,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.153846154,"of, the, coronavirus, has, and, sars-cov,"
6169,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.153846154,"the, virus, a, to, that, from, pangolin, and"
6170,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.153846154,"sars-cov-2, was, and, to, bats, the"
6171,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.153846154,"to, a, virus, that, from, and, the, pangolin"
6172,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.153846154,"the, of, from, and, which, identity, with, genome"
6173,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.153846154,"has, genome, identity, with, bat, that, and, a"
6174,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","Bats have been reported as being the rich source of 

coronaviruses",0.153846154,"been, of, the, have"
6175,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.153846154,"have, shown, to, sars-cov-2"
6176,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.153846154,"to, sars-cov-2, from, a, the, has, been, with"
6177,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.153846154,"the, to, have, has, been, with"
6178,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.153846154,"the, to, sars-cov-2, of, their, spike"
6179,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.153846154,"the, sars-cov-2, from, ratg13"
6180,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.153846154,"coronavirus, isolated, from, identity, with, sars-cov-2, has, the"
6181,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.153846154,"has, 96%, identity, ratg13"
6182,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.153846154,"a, to, that, the, of, sars-cov-2"
6183,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.153846154,"a, that, the, to, and, sars-cov-2"
6184,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.153846154,"and, the, of, that, by, a"
6185,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.153846154,"the, of, to, that, sars-cov-2, virus"
6186,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.153846154,"of, the, and, that, sars-cov-2, a"
6187,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.153846154,"the, of, be, to, between, and"
6188,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.153846154,"the, is, to, and"
6189,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.153846154,"the, of, sars-cov-2, to, is, humans, and, by"
6190,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.153846154,"the, virus, was, a, and, to"
6191,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.153846154,"bats, are, a, virus, the, china"
6192,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.153846154,"the, to, are, in, china, and"
6193,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.153846154,"most, scientists, that, the, of, to, about, origins"
6194,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.153846154,"the, virus, has, which, is, to, of, and"
6195,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.153846154,"the, is, virus, to, of, and, has, transmitted"
6196,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.153846154,"that, the, of, evidence, a, was"
6197,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.153846154,"a, was, at, that, the, virus, is, of"
6198,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.153846154,"the, to, that, in, virus, and"
6199,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.153846154,"that, the, and, to, is, sars-cov"
6200,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.153846154,"the, and, virus, is, to, that"
6201,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.153846154,"the, that, animal, origin"
6202,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.153846154,"is, to, its, in, the, that"
6203,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.153846154,"the, in, is, and"
6204,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.153846154,"and, of, the, huanan, in, 2019"
6205,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.153846154,"the, of, that, to, is, zoonotic"
6206,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.153846154,"bats, and, the, of"
6207,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.153846154,"the, to, bats, of, is, be"
6208,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.153846154,"the, that, is, to"
6209,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.153846154,"the, of, bat, it, is, as, reservoir, for"
6210,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.153846154,"contaminated, in, the, wild"
6211,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.153846154,"may, have, in, or"
6212,"with the first case being linked to  

a seafood market","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.153846154,"the, first, seafood, market"
6213,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.153846154,"that, the, outbreak, seafood, market, in"
6214,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.153846154,"that, the, virus, in, wuhan, seafood"
6215,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.153846154,"that, the, a, seafood, market, live, animals, in"
6216,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.153846154,"human, sars-cov-2, the, of"
6217,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.153846154,"sars-cov-2, has, genome, to"
6218,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.153846154,"of, the, sars-cov-2, to"
6219,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.153846154,"sars-cov-2, to, the, of"
6220,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.153846154,"to, of, sars-cov-2, the"
6221,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.153846154,"sars-cov, is, to, bat"
6222,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.153846154,"hosts, and, to, cause, severe, in, human, covs"
6223,Bats are hosts of many coronaviruses,"Coronaviruses are naturally hosted and developmentally 

formed by bats.",0.153846154,"are, coronaviruses"
6224,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.153846154,"the, of, has, been"
6225,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.153846154,"from, of, the, it, has, been, that, coronaviruses"
6226,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.153846154,"the, it, that, has, been, of"
6227,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.153846154,"the, of, to, that, have, between, and, sars-cov-2"
6228,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.153846154,"shown, to, have, sars-cov-2"
6229,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.153846154,"have, that, bats, of, sars-cov, and"
6230,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.153846154,"is, that, from, animal"
6231,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.153846154,"that, is, from, virus"
6232,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.153846154,"that, is, a, virus"
6233,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.153846154,"from, a, virus, is"
6234,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.153846154,"humans, it, is, the, when, first"
6235,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.153846154,"the, for, spillover, from"
6236,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.153846154,"the, are, all, bat, coronaviruses, to"
6237,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.153846154,"in, bat, have, genetic"
6238,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.153846154,"the, africa,, middle, east,, and, asia,"
6239,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.153846154,"ats, are, the, and"
6240,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.153846154,"the, and, introduced, virus, into, from, in, human, or, to"
6241,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.153846154,"that, is, from, animal"
6242,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.153846154,"sars-cov-2, is, that, humans, infected, the"
6243,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.153846154,"sars-cov-2, from, that, and"
6244,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.153846154,"it, is, that, sars-cov-2, through, of"
6245,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.153846154,"the, bat, and, ratg13,, sequence, with"
6246,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.153846154,"the, to, from, bats, of, be"
6247,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.153846154,"the, covid-19, to, be"
6248,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.153846154,"the, genome, to, be"
6249,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.153846154,"are, zoonotic, and, the, that, to"
6250,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.153846154,"the, is, to, that, of, coronavirus"
6251,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.153846154,"the, has, of, sars-cov,, and, coronavirus"
6252,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.153846154,"has, identity, with, bat, and, human"
6253,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.153846154,"revealed, that, is, the, bat, and"
6254,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.153846154,"that, seafood, market, in, the, outbreak"
6255,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.153846154,"that, the, in, seafood, market, live, animals, a"
6256,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.153846154,"a, and, at, market, in, 2019"
6257,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.153846154,"sars-cov-2, from, a, virus, in, bat"
6258,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.153846154,"a, virus, from, is"
6259,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.153846154,"is, that, sars-cov-2, from"
6260,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.153846154,"a, sars-cov-2, virus, from, bat, in"
6261,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.153846154,"is, virus, sars-cov-2, in"
6262,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.153846154,"a, two, that, the, of, sars-cov-2"
6263,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.153846154,"of, a, analysis, that, the, and"
6264,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.153846154,"animal, sars-cov-2, and, the"
6265,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.153846154,"and, the, of, sars-cov-2"
6266,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.153846154,"to, the, most, of, sars-, be"
6267,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Bats are natural hosts of many of the known  

coronaviruses",0.153846154,"the, are, known, of"
6268,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Bats are natural hosts of many of the known  

coronaviruses",0.153846154,"hosts, are, the, of"
6269,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Bats are natural hosts of many of the known  

coronaviruses",0.153846154,"the, bats, are, hosts"
6270,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.153846154,"sars-cov-2, (zhu, et, al.,, 2020), and, to, bats"
6271,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.153846154,"the, intermediate, to, be"
6272,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.153846154,"the, a, coronavirus, has, with, similarity"
6273,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.153846154,"to, is, of, the, virus, has, and, transmitted"
6274,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.153846154,"that, been, a, of, virus, to, and, the"
6275,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.153846154,"that, the, coronavirus, was, at, of"
6276,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.153846154,"the, that, in, a, genome, to"
6277,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.153846154,"at, a, in, the, that, to"
6278,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.153846154,"similar, to, the, coronavirus, in, of, that, a"
6279,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.153846154,"to, that, the, of, sars-, cov-2"
6280,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.153846154,"the, of, at, that, a, in"
6281,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.153846154,"the, of, sars-cov-2, human"
6282,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.153846154,"the, at, huanan, seafood, and, hospital, of, on, with, pneumonia"
6283,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.153846154,"is, at, the, to, in, wuhan"
6284,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.153846154,"to, sars-cov-2, bats, and, was, the"
6285,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.153846154,"sars-cov-2, and, (zhu, et, al.,, 2020), to, bats"
6286,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.153846154,"sars-cov-2, to, a, of, an, the"
6287,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.153846154,"to, the, a, isolated, from, sars-cov-2"
6288,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.153846154,"et, the, of, to, sars-cov-2, in"
6289,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.153846154,"the, was, in, bat"
6290,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.153846154,"the, that, origin, animal"
6291,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.153846154,"that, the, origin, of"
6292,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.153846154,"in, the, of, for, that, and, within, a"
6293,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.153846154,"has, been, the, of"
6294,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.153846154,"the, for, viruses, in"
6295,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.153846154,"the, ratg13, from, sars-cov-2"
6296,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.153846154,"sars-cov-2, from, ratg13, and"
6297,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.153846154,"from, the, origin, of, between, and"
6298,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.153846154,"in, found, related, of, pangolin, which, similar, to"
6299,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.153846154,"are, the, virus, bats, a, china"
6300,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.153846154,"has, been, the, in, of, and"
6301,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.153846154,"of, the, in, and, sars-cov-2, viruses"
6302,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.153846154,"bats, as, the, for, of, and"
6303,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.153846154,"genome, sars-cov-2, has, to"
6304,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.153846154,"the, were, in, shared, with, sars-cov-2"
6305,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.153846154,"sars-cov-2, in, the, host, with, cov"
6306,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.153846154,"of, most, to, the, bat, coronaviruses,"
6307,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.153846154,"the, virus, was, had, been, by"
6308,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.153846154,"in, the, that, sars-cov-2, related, to"
6309,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.153846154,"that, sars-cov-2, is, not"
6310,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.153846154,"is, to, in, the, that, not"
6311,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.153846154,"the, in, and, that, for, a, within, of"
6312,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.153846154,"the, genome, of, which, identity, with, from, and"
6313,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.153846154,"were, sars-cov-2, shared, with, the, in"
6314,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.153846154,"two, from, the, and, nucleotide, with"
6315,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.153846154,"with, a, coronavirus, sars-cov-2"
6316,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.153846154,"a, bat, of, sars-cov-2, genome, in"
6317,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.153846154,"to, the, sars-cov-2, is"
6318,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.153846154,"is, that, the, to"
6319,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.153846154,"the, to, sars-cov-2, in, of, et"
6320,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.153846154,"the, sars-cov-2, found, to"
6321,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.153846154,"et, al., (2020), in, the, to, of, found"
6322,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.153846154,"were, from, bats, of, species, and"
6323,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.153846154,"sars-cov-2, from, an, to, several, and, in, species"
6324,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.153846154,"to, the, sars-cov-2, of, humans, from"
6325,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.153846154,"the, to, sars-cov-2, infection, and, of"
6326,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.153846154,"of, sars-cov-2, to, ace2, the, in"
6327,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.153846154,"the, sequence, and, with, bat, ratg13,"
6328,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.153846154,"the, nucleotide, from, two, and, with"
6329,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.153846154,"the, key, residues, rbd, pangolin-cov, with"
6330,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.153846154,"for, the, of, and, intermediate, species, that, a, in, or, with, as"
6331,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.153846154,"in, a, study, that, the, to"
6332,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.153846154,"the, to, and, that, was, a"
6333,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.153846154,"a, to, that, sars-cov-2, the, and"
6334,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.153846154,"the, of, sars-cov-2, and, be, to"
6335,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.153846154,"the, of, and, sars-cov-2, is, to, humans, by"
6336,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.153846154,"evidence, that, the, was, of, a"
6337,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.153846154,"the, sars-cov-2, animal, and"
6338,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.153846154,"this, of, at, the, market, in"
6339,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.153846154,"the, presence, in, of, that, sars-cov-2"
6340,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.153846154,"a, from, the, has, been, to, with, sars-cov-2"
6341,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.153846154,"it, has, been, that, the, of, coronaviruses, from"
6342,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Bats are the second  

largest order of mammals, with over 1,230 species.",0.153846154,"with, bats, the, of"
6343,Bats are hosts of many coronaviruses,Coronaviruses account for over 30% of the world’s viruses.,0.153846154,"of, coronaviruses"
6344,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.153846154,"the, of, and, viruses"
6345,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.153846154,"the, of, bats, as, for, and"
6346,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.153846154,"the, as, animal, for"
6347,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.153846154,"the, of, sars-cov-2, and, to, bat"
6348,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.153846154,"are, and, the, to, in, china"
6349,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.153846154,"coronaviruses, to, sars-cov-2, in, the, including, all, that"
6350,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.153846154,"that, the, most, closely, bat, discovered"
6351,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.153846154,"that, most, to, the, bat, and"
6352,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.153846154,"bat, in, china, coronaviruses, including, sars-cov-2"
6353,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.153846154,"the, in, viruses, for"
6354,"An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.153846154,"an, of, bat, species"
6355,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.153846154,"the, of, bat, to, viruses, as, a, closely, infect, that, in, recombination, events, can"
6356,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.153846154,"that, the, of, bat, in, recombination, events, as, closely, viruses, can, infect, a, to"
6357,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.153846154,"to, their, the, spike, of, sars-cov-2"
6358,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.153846154,"the, of, that, to, with, than"
6359,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.153846154,"the, also, in, of"
6360,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.153846154,"is, the, most, as, to, bat"
6361,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.153846154,"in, is, the, covid-19, be, sars-cov-2"
6362,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.153846154,"sars-cov-2, is, virus, to, the, most"
6363,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.153846154,"in, the, is, to, sars-cov-2, virus"
6364,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.153846154,"the, sars-cov-2, and, to, a, in, other, bat, coronaviruses, recombination"
6365,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.153846154,"when, humans, the, first, it, is"
6366,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.153846154,"is, the, sars-cov-2, be, in, covid-19"
6367,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.153846154,"on, the, hospital, of, and, with, pneumonia, at, huanan, seafood"
6368,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.153846154,"the, virus, introduced, into, human, from, in, or, to, and"
6369,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.153846154,"in, a, of, species, and, that, the, with, as, or, intermediate, for"
6370,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.153846154,"that, the, virus, in, and, to, humans, intermediate, december, of"
6371,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.153846154,"in, the, of, researchers, would, a, to, bat, as, by, taken, with, sars,, could, sars-related, similar, and, that, sars, from, this, yunnan, first, its"
6372,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.153846154,"from, the, first, to, a, sars-related, that, similar, with, this, bat, sars,, as, and, could, researchers, would, by, sars, in, of, taken, yunnan, its"
6373,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.153846154,"the, association, known, covid-19, cases, and, huanan, market, is, of, a, to"
6374,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.153846154,"the, huanan, market, is, of, cases, to, and, a, known, covid-19, association"
6375,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.153846154,"and, are, known, to, the, animal"
6376,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.153846154,"are, zoonotic, to, the, that, and"
6377,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.153846154,"a, in, the, that, to, at"
6378,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.153846154,"that, cause, virus, natural, to, for, the, into"
6379,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.153846154,"is, that, sars-cov-2, the, infected, humans"
6380,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.153846154,"is, the, most, virus, to, sars-cov-2"
6381,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.153846154,"a, for, sars-cov-2, found, to, infected, with, that"
6382,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","expended to make the simple point 

that COVID-19 had a natural origin.",0.153846154,"that, the, had, to"
6383,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","expended to make the simple point 

that COVID-19 had a natural origin.",0.153846154,"a, that, the, covid-19"
6384,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","expended to make the simple point 

that COVID-19 had a natural origin.",0.153846154,"the, to, natural, origin."
6385,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.153846154,"and, sars-cov-2, in, china,, to, bats"
6386,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.153846154,"and, the, of, which, a, natural"
6387,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.153846154,"of, a, the, to, which, and"
6388,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.153846154,"an, host, and, humans, was, in"
6389,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.153846154,"that, is, not, sars-cov-2"
6390,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.153846154,"the, of, evidence, this, that, sars-cov-2, is, a"
6391,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.153846154,"is, it, that, of, sars-cov-2, through"
6392,"Bats have been reported as being the rich source of 

coronaviruses","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.153846154,"have, been, the, of"
6393,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.153846154,"virus, that, is, from"
6394,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.153846154,"from, virus, that, is"
6395,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.153846154,"for, the, as, reservoir, of, bat, is, it"
6396,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.153846154,",, similarity, to, the, that, for, is, of"
6397,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.153846154,"that, bats, the, hosts, for, its"
6398,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.153846154,"the, is, to, that, its, in"
6399,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.153846154,"the, that, is, not, in, to"
6400,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.153846154,"the, coronaviruses, to, that, sars-cov-2, all, in, including"
6401,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.153846154,"the, similarity, of, to, ,, is, that, for"
6402,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.153846154,"a, of, that, by, the, and"
6403,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.153846154,"a, of, natural, and, which, the"
6404,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.153846154,"the, that, sars-cov-2, a, of, into"
6405,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.153846154,"of, to, that, sars-cov-2, the, virus"
6406,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.153846154,"the, that, presence, of, in, sars-cov-2"
6407,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.153846154,"that, the, genome, of, a, bat"
6408,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.153846154,"the, discovered, that, most, closely, bat"
6409,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.153846154,"the, of, evidence, that, is, a, animal, for"
6410,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.153846154,"and, in, china,, to, bats, of"
6411,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.153846154,"that, seafood, in, wuhan, the, virus"
6412,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.153846154,"in, december, the, of, intermediate, that, virus, humans, to, and"
6413,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.153846154,"the, of, covid-19, seafood, in, wuhan"
6414,"Coronaviruses are naturally hosted and developmentally 

formed by bats.",Bats are hosts of many coronaviruses,0.153846154,"coronaviruses, are"
6415,Coronaviruses account for over 30% of the world’s viruses.,Bats are hosts of many coronaviruses,0.153846154,"coronaviruses, of"
6416,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.153846154,"is, to, be, the"
6417,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.153846154,"is, the, be, to"
6418,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.153846154,"to, be, the, covid-19"
6419,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.153846154,"that, the, most, of"
6420,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.153846154,"most, that, was, the, of, and, is, to"
6421,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.153846154,"revealed, that, the, and, bat, is"
6422,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.153846154,"to, the, of, coronaviruses,, most, bat"
6423,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.153846154,"the, to, that, most, bat, and"
6424,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.153846154,"the, to, covid-19, for, is, most"
6425,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.153846154,"a, coronavirus, in, the, that, similar, to, of"
6426,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.153846154,"that, 2, have, been, a, of, similar, to, and, the"
6427,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.153846154,"the, covid-19, in, wuhan, seafood, of"
6428,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.153846154,"the, has, been, to, have, with"
6429,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.153846154,"studies, have, bats, the, a, of"
6430,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.153846154,"is, to, be, from"
6431,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.153846154,"and, was, in, an, host, humans"
6432,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.153846154,"in, the, of, pangolins, (manis, javanica)"
6433,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.153846154,"contaminated, wild, in, the"
6434,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.153846154,"the, of, that, is, this, covid-19"
6435,"expended to make the simple point 

that COVID-19 had a natural origin.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.153846154,"the, that, covid-19, a"
6436,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.153846154,"covid-19, is, most, to, the, for"
6437,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.153846154,"has, a, genome, identity, with, that, and, bat"
6438,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.153846154,"has, and, identity, with, bat, human"
6439,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.153846154,"the, coronavirus, isolated, from, has, identity, with, sars-cov-2"
6440,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.153846154,"the, is, and, in"
6441,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.153846154,"virus, that, is, a"
6442,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.153846154,"the, of, is, sars-cov-2, that, virus"
6443,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.153846154,"that, not, it, an, sars-cov-2, to, from, in"
6444,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.153846154,"a, recent, bat, from, in, sars-cov-2"
6445,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.153846154,"that, the, of, sars-cov-2, has, been"
6446,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.153846154,"the, have, been, reservoirs, and, other"
6447,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.153846154,"sars-cov-2, to, be, the"
6448,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.153846154,"genome, to, be, the"
6449,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.153846154,"found, the, to, sars-cov-2"
6450,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.153846154,"sars-cov-2, the, bat, cov"
6451,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.153846154,"bat, be, the, sars-cov-2"
6452,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.153846154,"genetic, and, is, a, virus, that"
6453,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.153846154,"the, that, a, of, natural, origin"
6454,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.153846154,"is, a, and, origin, of, the"
6455,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.153846154,"the, of, has, as, a, human"
6456,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.153846154,"ratg13, has, 96%, identity"
6457,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.153846154,"that, sars-cov-2, and, from"
6458,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.153846154,"sars-cov-2, from, and, ratg13"
6459,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.153846154,"sars-cov-2, identical, and, to"
6460,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.153846154,"one, of, these, similarity, genome, bat"
6461,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.153846154,"this, is, and, ratg13, to, the, between, that"
6462,"expended to make the simple point 

that COVID-19 had a natural origin.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.153846154,"to, the, natural, origin."
6463,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.153846154,"in, ace2, of, to, sars-cov-2, the"
6464,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.153846154,"the, to, its, in, rbd, of"
6465,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.153846154,"to, be, the, most, of, sars-"
6466,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.153846154,"the, that, bats, hosts, for, its"
6467,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.153846154,"sars-cov-2, to, a, coronavirus, and, the"
6468,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.153846154,"to, the, a, coronavirus, from, sars-cov-2"
6469,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.153846154,"that, bats, are, sars-cov-2"
6470,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.153846154,"is, at, that, the, virus, was, of, a"
6471,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.153846154,"et, al., (2020), found, the, of, to, in"
6472,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.153846154,"the, most, to, as, is, bat"
6473,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.153846154,"the, as, for, sars-cov-2"
6474,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.153846154,"the, sars, and, sars-like, many, to"
6475,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.153846154,"the, to, bat, and, that, a"
6476,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.153846154,"a, analysis, of, the, that, and"
6477,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.153846154,"a, of, and, to, which, the"
6478,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.153846154,"a, bat, in, genome, of, sars-cov-2"
6479,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.153846154,"one, of, these, bat, genome, similarity"
6480,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.153846154,"found, in, of, which, related, to, similar, pangolin"
6481,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.153846154,"the, that, virus, to, a, of, and, been"
6482,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.153846154,"similar, to, the, 2, have, been, of, and, that, a"
6483,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.153846154,"the, of, that, sars-cov-2, a, virus, been, for"
6484,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.153846154,"with, the, and, sars-cov-2, in, of"
6485,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.153846154,"in, a, show, that, the, two"
6486,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.153846154,"with, a, and, of, the, in"
6487,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.153846154,"a, of, that, sars-cov-2, the, and"
6488,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.153846154,"sars-cov-2, the, viruses, in, and, of"
6489,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.153846154,"is, that, the, of"
6490,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.153846154,"that, the, is, of"
6491,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.153846154,"we, that, sars-cov-2, the"
6492,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.153846154,"of, sars-cov-2, has, been, that, the"
6493,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.153846154,"this, suggests, that, and, the, of"
6494,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.153846154,"the, that, sars-cov-2, is, in, bat"
6495,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.153846154,"is, to, the, that, ratg13, between, and, this"
6496,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.153846154,"host, sars-cov-2, with, the, cov, in"
6497,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.153846154,"the, sars-cov-2, bat, cov"
6498,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.153846154,"the, that, origin, of"
6499,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.153846154,"this, the, pangolin, sars-cov-2"
6500,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.153846154,"or, in, may, have"
6501,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.153846154,"the, origin, of, between, from, and"
6502,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.153846154,"the, and, sequences, are, similar, to"
6503,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.153846154,"the, and, sars-cov-2, to, of, genome"
6504,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.153846154,"that, the, of, with, to, than"
6505,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.153846154,"to, that, sars-cov-2, has, highest, similarity"
6506,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.153846154,"that, sars-cov-2, to, bat-sl-cov-2"
6507,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.153846154,"sars-cov-2, identical, to, and"
6508,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.153846154,"the, of, is, identical, to, sars-cov-2"
6509,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.153846154,"from, for, the, spillover"
6510,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.153846154,"bat-sl-cov-2, the, and, for"
6511,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.153846154,"the, in, emergence, of"
6512,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.153846154,"in, the, of, pangolin-cov, sars-cov-2, that"
6513,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.153846154,"and, have, that, sars-cov, bats, of"
6514,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.153846154,"studies, have, a, of, bats, the"
6515,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.153846154,"the, for, bat-sl-cov-2, and"
6516,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.153846154,"the, to, sars-cov-2, in"
6517,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.153846154,"the, and, pangolin-cov, sars-cov-2"
6518,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.153846154,"that, the, of, and, suggests, this"
6519,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.153846154,"at, has, the, closest, relationship, with"
6520,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.153846154,"is, the, virus, to, sars-cov-2, in"
6521,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.153846154,"of, the, that, sars-cov-2, is, virus"
6522,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.153846154,"the, of, sars-cov-2, is, identical, to"
6523,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.153846154,"pangolin-cov, that, in, the, of, sars-cov-2"
6524,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.153846154,"the, for, sars-cov-2, as"
6525,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.153846154,"the, sars-cov-2, this, pangolin"
6526,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.153846154,"that, sars-cov-2, has, highest, similarity, to"
6527,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.153846154,"the, pangolin-cov, key, rbd, residues, with"
6528,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.153846154,"was, in, the, bat"
6529,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.153846154,"as, the, animal, for"
6530,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.153846154,"from, to, is, be"
6531,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.153846154,"most, of, the, that"
6532,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.153846154,"the, sars-cov-2, be, bat"
6533,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.153846154,"a, in, the, that, of, at"
6534,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.153846154,"the, of, sars-cov-2, is, a, that, this, evidence"
6535,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.153846154,"of, evidence, that, the, is, a, animal, for"
6536,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.153846154,"that, been, a, of, virus, the, for, sars-cov-2"
6537,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.153846154,"that, the, sars-cov-2, a, laboratory, or"
6538,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.153846154,"coronaviruses, sars-cov-2, bat, in, china, including"
6539,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.153846154,"recent, sars-cov-2, from, a, bat, in"
6540,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.153846154,"sars-cov-2, a, that, found, with, infected, to, for"
6541,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.153846154,"human, covs, cause, to, severe, in, and, hosts"
6542,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.153846154,"the, has, closest, relationship, with, at"
6543,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.153846154,"the, to, was, detected, in, yunnan"
6544,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.153846154,"rbd, of, to, the, its, in"
6545,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.153846154,"the, of, sars-, cov-2, to, is"
6546,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.153846154,"a, the, that, sars-cov-2, laboratory, or"
6547,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.153284672,"with, the, and, for, of, a, to, that, were, in, is, sars, live, animal, palm, civets,, likely, infected, other, by, market"
6548,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.153284672,"the, live, to, in, a, for, of, with, is, likely, sars, that, infected, were, by, animal, and, palm, civets,, other, market"
6549,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.153153153,"the, to, in, wet, a, for, of, with, sars, that, virus, by, animal, traders, province, palm, market"
6550,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.153153153,"a, of, wet, market, in, province, that, animal, traders, for, sars, with, palm, by, the, to, virus"
6551,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.153153153,"the, huanan, market, wuhan, in, for, of, january, 2020, to, chinese, and, experts, with, a, early, an"
6552,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.153153153,"chinese, for, and, an, with, experts, wuhan, to, the, huanan, market, in, early, of, january, 2020, a"
6553,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.152941176,"for, the, of, and, host, that, virus, into, a, in, with, as, to"
6554,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.152941176,"a, for, as, the, of, virus, and, in, with, that, to, into, host"
6555,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.152777778,"the, that, are, also, with, of, is, use, as, an, for"
6556,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.152777778,"sars-cov-2, be, based, on, the, and, with, to, in, rbd, potential"
6557,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.152777778,"are, also, for, as, the, of, is, with, that, use, an"
6558,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.152777778,"and, be, potential, sars-cov-2, to, based, on, the, in, rbd, with"
6559,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.152542373,"sars-cov, and, bat, coronaviruses, a, in, viruses, are, to"
6560,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.152542373,"the, virus, of, which, to, with, from, and, bat"
6561,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.152542373,"the, of, and, bat, coronaviruses, that, viruses, are, to"
6562,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.152542373,"the, and, to, that, these, bat, coronaviruses, are, of"
6563,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.152542373,"have, that, the, in, to, humans, from, animals, a"
6564,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.152542373,"to, with, the, of, and, which, from, bat, virus"
6565,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.152542373,"from, in, humans, the, that, a, animals, have, to"
6566,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.152542373,"isolated, from, in, the, sequence, of, s, protein, on"
6567,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.152542373,"sars-cov, and, are, to, bat, coronaviruses, in, a, viruses"
6568,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.152542373,"the, viruses, and, are, of, bat, coronaviruses, that, to"
6569,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.152542373,"to, be, the, of, sars-, bats, are, likely, hosts"
6570,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.152542373,"to, sars-cov-2, in, from, a, bat, (zhou, et, al.,"
6571,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.152542373,"sars-cov-2, a, from, bat, et, al.,, to, (zhou, in"
6572,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.152542373,"of, the, in, and, that, sars-cov-2, sequences, a, with"
6573,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.152542373,"a, in, the, virus, is, closely, related, to, of"
6574,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.152542373,"another, of, evidence, that, the, is, a, ace2, or"
6575,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.152542373,"the, of, ace2, is, a, or, that, another, evidence"
6576,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.152542373,"on, sequence, in, the, s, protein, of, isolated, from"
6577,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.152542373,"the, is, of, to, a, closely, related, virus, in"
6578,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.152542373,"sars-cov-2, a, of, sequences, in, the, and, that, with"
6579,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.152542373,"bats, are, to, be, the, likely, hosts, of, sars-"
6580,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.152542373,"the, and, are, of, bat, coronaviruses, that, these, to"
6581,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.152173913,"sars-cov-2, to, a, contains, bat, and, pangolin"
6582,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.152173913,"bats, are, the, of, in, southern, china"
6583,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.152173913,"is, no, that, the, virus, was, a"
6584,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.152173913,"t, is, that, the, virus, because, sequence"
6585,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.152173913,"that, sars-cov-2, genome, to, cov, and, the"
6586,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.152173913,"whole, genome, of, the, in, with, and"
6587,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.152173913,"and, in, to, the, of, sars-cov-2, is"
6588,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.152173913,"the, of, and, more, been, viruses, bats"
6589,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.152173913,"a, was, that, the, and, to, is"
6590,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.152173913,"in, the, sequence, that, was, to, virus"
6591,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.152173913,"a, is, to, in, the, that, human"
6592,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.152173913,"the, that, in, it, to, wet, market"
6593,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.152173913,"the, covid-19, is, of, zoonotic, to, in"
6594,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.152173913,"animal, zoonotic, this, in, the, that, to"
6595,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.152173913,"this, to, that, the, of, origin, is"
6596,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.152173913,"the, of, this, that, is, in, animal"
6597,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.152173913,"the, of, is, to, sars-cov-2, and, a"
6598,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.152173913,"the, most, are, species, of, bats, and"
6599,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.152173913,"and, sars-, the, bats, be, natural, of"
6600,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.152173913,"to, the, that, as, into, from, natural"
6601,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.152173913,"that, the, hosts, for, sars-cov, and, mers-cov"
6602,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.152173913,"ratg13,, the, to, was, in, from, yunnan"
6603,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.152173913,"in, the, was, identifed, animals, to, and"
6604,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.152173913,"the, was, identifed, in, and, to, animals"
6605,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.152173913,"the, coronavirus, was, transmitted, to, animals, a"
6606,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.152173913,"are, in, animals, and, transmitted, to, humans"
6607,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.152173913,"to, the, of, bats, and, are, sars-cov-2"
6608,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.152173913,"to, sars-cov-2, is, be, from, bats, the"
6609,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.152173913,"several, animal, species, to, sars-cov-2, and, in"
6610,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.152173913,"from, as, that, natural, to, the, into"
6611,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.152173913,"to, the, evidence, of, sars-cov-2, natural, origin"
6612,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.152173913,"two, viruses, of, the, sars-cov-2, lineage, from"
6613,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.152173913,"at, this, bat, the, sars-cov-2, that, are"
6614,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.152173913,"the, that, to, wet, market, in, it"
6615,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.152173913,"the, similarity, and, virus, to, that, bat"
6616,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.152173913,"the, to, genome,, from, an, of, horseshoe"
6617,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.152173913,"the, sars-cov-2, to, from, bats, is, be"
6618,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.152173913,"has, a, sars-cov-2, and, the, of, virus"
6619,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.152173913,"by, and, to, the, of, sars-cov-2, has"
6620,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.152173913,"and, be, intermediate, hosts, to, the, between"
6621,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.152173913,"the, was, from, a, market, and, to"
6622,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.152173913,"is, that, was, a, no, the, virus"
6623,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.152173913,"is, that, a, the, of, virus, at"
6624,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.152173913,"the, was, reported, market,, in, involved, of"
6625,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.152173913,"t, is, that, because, the, virus, sequence"
6626,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.152173913,"the, of, virus, is, to, that, and"
6627,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.152173913,"a, is, the, to, that, and, was"
6628,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.152173913,"the, to, for, which, a, is, also"
6629,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.152173913,"the, virus, that, bat, and, similarity, to"
6630,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.152173913,"and, that, the, virus, to, of, bat"
6631,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.152173913,"et, that, the, between, and, bat, is"
6632,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.152173913,"virus, sequence, that, 96.2%, the, sars-cov-2, bat"
6633,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.152173913,"the, similarity, of, to, bat, is, that"
6634,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.152173913,"of, viruses, are, a, in, the, same"
6635,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.152173913,"he, isolated, from, in, the, of, protein"
6636,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.152173913,"is, not, that, sars-cov-2, has, and, a"
6637,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.152173913,"with, the, and, in, of, whole, genome"
6638,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.152173913,"bats, be, the, natural, of, sars-, and"
6639,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.152173913,"the, and, of, virus, to, that, bat"
6640,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.152173913,"sars-cov-2, a, natural, that, through, on, the"
6641,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.152173913,"the, between, and, et, is, that, bat"
6642,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.152173913,"a, of, has, sars-cov-2, the, and, virus"
6643,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.152173913,"that, a, of, with, similar, to, the"
6644,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.152173913,"the, to, ratg13,, was, in, from, yunnan"
6645,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.152173913,"the, an, genome,, to, of, from, horseshoe"
6646,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.152173913,"the, to, that, in, sequence, virus, was"
6647,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.152173913,"the, to, that, closely, related, sars-cov-2, in"
6648,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.152173913,"virus, sequence, that, the, sars-cov-2, in, its"
6649,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.152173913,"the, rbd, of, to, that, sars-cov-2, was"
6650,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.152173913,"the, a, coronavirus, was, transmitted, animals, to"
6651,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.152173913,"a, of, viruses, and, to, which, the"
6652,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.152173913,"a, with, pangolins, the, intermediate, for, sars-cov-2"
6653,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.152173913,"sars-cov-2, is, to, a, of, and, the"
6654,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.152173913,"that, sars-cov-2, has, a, and, is, not"
6655,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.152173913,"this, a, that, the, is, of, and"
6656,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.152173913,"of, sequences, genome, which, from, rhinolophus, in"
6657,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.152173913,"the, of, sars-cov-2, to, species, humans, and"
6658,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.152173913,"the, to, be, intermediate, hosts, between, and"
6659,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.152173913,"species, of, to, sars-cov-2, and, the, humans"
6660,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.152173913,"it, is, possible, of, sars-cov-2, the, through"
6661,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.152173913,"sars-cov-2, animal, to, several, and, in, species"
6662,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.152173913,"is, at, that, the, virus, of, a"
6663,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.152173913,"the, of, to, in, is, zoonotic, covid-19"
6664,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.152173913,"bats, and, are, the, of, most, species"
6665,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.152173913,"in, the, that, sars-cov-2, closely, related, to"
6666,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.152173913,"of, the, are, same, in, viruses, a"
6667,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.152173913,"the, banal, closely, related, to, sars-cov-2,, is"
6668,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.152173913,"banal, closely, related, to, sars-cov-2,, the, is"
6669,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.152173913,"that, the, covid-19, in, and, humans, through"
6670,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.152173913,"and, the, was, from, to, a, market"
6671,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.152173913,"the, that, to, animal, in, this, zoonotic"
6672,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.152173913,"on, the, that, sars-cov-2, through, natural, a"
6673,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.152173913,"the, of, to, a, and, which, viruses"
6674,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.152173913,"and, in, their, to, the, of, natural"
6675,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.152173913,"the, sars-cov-2, sequence, virus, 96.2%, that, bat"
6676,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.152173913,"its, in, the, sequence, that, sars-cov-2, virus"
6677,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.152173913,"the, similarity, of, is, to, that, bat"
6678,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.152173913,",, is, to, its, the, that, it"
6679,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.152173913,"a, is, the, to, that, in, human"
6680,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.152173913,"the, to, ,, it, is, that, its"
6681,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.152173913,"that, not, from, a, to, it, in"
6682,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.152173913,"the, of, sars-cov-2, through, it, is, possible"
6683,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.152173913,"the, was, to, this, that, in, of"
6684,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.152173913,"rbd, of, sars-cov-2, the, scenario, in, plausible"
6685,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.152173913,"in, humans, through, that, the, covid-19, and"
6686,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.152173913,"in, are, transmitted, animals, to, humans, and"
6687,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.152173913,"the, bats, are, in, of, southern, china"
6688,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.152173913,"market,, in, the, was, reported, involved, of"
6689,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.152173913,"the, in, of, to, that, this, was"
6690,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.152173913,"viruses, two, the, of, sars-cov-2, from, lineage"
6691,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.152173913,"of, the, two, in, and, sars-cov-2, viruses"
6692,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.152173913,"he, of, the, protein, in, isolated, from"
6693,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.152173913,"the, of, is, that, and, this, a"
6694,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.152173913,"a, the, also, for, to, which, is"
6695,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.152173913,"from, a, to, in, that, it, not"
6696,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.152173913,"the, and, sars-cov-2, is, to, in, of"
6697,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.152173913,"evidence, to, the, sars-cov-2, of, natural, origin"
6698,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.152173913,"of, to, has, sars-cov-2, by, the, and"
6699,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.152173913,"of, in, their, natural, and, to, the"
6700,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.152173913,"this, be, that, the, between, and, an"
6701,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.152173913,"sars-cov-2, the, rbd, in, of, scenario, plausible"
6702,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.152173913,"the, of, that, to, is, this, origin"
6703,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.152173913,"and, sars-cov-2, to, bat, pangolin, a, contains"
6704,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.152173913,"are, to, the, that, bats, hosts, for"
6705,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.152173913,"sequences, of, from, rhinolophus, which, in, genome"
6706,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.152173913,"a, the, with, that, similar, to, of"
6707,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.152173913,"pangolins, a, intermediate, for, sars-cov-2, with, the"
6708,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.152173913,"two, viruses, of, the, sars-cov-2, in, and"
6709,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.152173913,"that, bats, are, the, hosts, for, to"
6710,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.152173913,"are, at, bat, that, the, sars-cov-2, this"
6711,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.152173913,"bats, the, been, of, and, more, viruses"
6712,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.152173913,"the, of, sars-cov-2, are, bats, and, to"
6713,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.152173913,"genome, the, to, cov, and, that, sars-cov-2"
6714,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.152173913,"hosts, that, for, sars-cov, and, mers-cov, the"
6715,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.152173913,"the, that, an, between, and, this, be"
6716,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.152173913,"the, of, that, sars-cov-2, was, to, rbd"
6717,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.152173913,"the, of, that, animal, in, is, this"
6718,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.151898734,"from, in, found, to, that, the, of, sars-, coronavirus, is, bats, sars-cov-2"
6719,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.151898734,"the, to, in, for, viruses, southern, sars, progenitor, virus, were, and, other"
6720,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.151898734,"the, progenitor, virus, for, sars, and, other, viruses, to, were, in, southern"
6721,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.151898734,"et, al., that, may, by, of, with, to, and, are, the, sars-cov-2"
6722,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.151898734,"from, in, were, found, to, closely, related, that, the, of, is, bats"
6723,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.151898734,"et, al., that, are, the, sars-cov-2, to, by, may, with, of, and"
6724,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.151898734,"that, of, sars-, from, bats, to, is, coronavirus, found, in, sars-cov-2, the"
6725,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.151898734,"from, in, that, the, is, closely, related, to, of, were, found, bats"
6726,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.151785714,"had, to, a, palm, animal, in, tested, for, the, virus, or, by, wet, sars, exposure, suggesting, of"
6727,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.151785714,"a, of, wet, in, animal, tested, for, sars, palm, by, had, the, suggesting, or, exposure, to, virus"
6728,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.151785714,"the, southern, of, a, to, live, animal, in, wet, markets, and, animals, market, were, virus, was, palm"
6729,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.151785714,"the, live, animals, to, in, wet, markets, a, of, southern, was, virus, were, animal, and, palm, market"
6730,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.151515152,"and, species, to, the, of"
6731,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.151515152,"coronaviruses, to, bat, in, and"
6732,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.151515152,"genetic, to, sars-cov, and, in"
6733,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.151515152,"is, to, its, in, than"
6734,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.151515152,"a, coronavirus, been, have, sars-cov-2"
6735,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.151515152,"of, amino, the, site, spike, in, a, to, insertion, naturally"
6736,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.151515152,"that, sars-cov-2, is, a, naturally"
6737,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.151515152,"the, is, to, of, bat"
6738,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.151515152,"the, is, to, sars-cov, that"
6739,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.151515152,"of, the, are, viruses, a"
6740,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.151515152,"the, of, natural, a, and"
6741,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.151515152,"the, of, in, is, to"
6742,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.151515152,"the, of, and, in, bat"
6743,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.151515152,"and, in, the, of, sars-cov-2"
6744,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.151515152,"a, in, the, of, bats"
6745,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.151515152,"bats, as, the, for, of"
6746,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.151515152,"to, seafood, wholesale, market, in"
6747,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.151515152,"sars-cov-2, a, and, an, animal"
6748,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.151515152,"the, bats, and, hosts, of"
6749,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.151515152,"bats, and, are, the, of"
6750,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.151515152,"the, sars-cov-2, with, is, to"
6751,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.151515152,"the, of, other, coronaviruses, to"
6752,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.151515152,"and, the, was, to, in"
6753,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.151515152,"the, to, in, animals, and"
6754,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.151515152,"the, to, bats,, and, animals"
6755,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.151515152,"the, was, from, in, china"
6756,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.151515152,"is, of, lineage, the, in"
6757,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.151515152,"analysis, of, that, sars-cov-2, the"
6758,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.151515152,"analysis, of, the, sars-cov-2, that"
6759,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.151515152,"the, that, of, in, sars-cov-2"
6760,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.151515152,"in, that, the, of, bat"
6761,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.151515152,"that, the, of, and, to"
6762,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.151515152,"of, bat, genome, with, sars-cov-2"
6763,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.151515152,"that, sars-cov-2, the, with, bat"
6764,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.151515152,"bat, the, of, sars-cov-2, and"
6765,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.151515152,"the, showed, for, viral, that"
6766,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.151515152,"the, of, that, bats, for"
6767,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.151515152,"the, of, showed, that, bats"
6768,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","with the first case being linked to  

a seafood market",0.151515152,"the, to, with, a, market"
6769,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.151515152,"from, in, found, to, be, the, of, is, bats, sars-cov-2"
6770,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.151515152,"the, origin, that, in, and"
6771,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.151515152,"been, identified, as, a, species, likely, from, to, bat, and"
6772,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.151515152,"that, sars-cov-2, the, humans, from"
6773,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.151515152,"evidence, that, the, of, sars-cov-2"
6774,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.151515152,"the, hypothesis, was, that, of"
6775,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.151515152,"the, to, be, of, known"
6776,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.151515152,"the, to, sars-cov-2, known, be"
6777,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.151515152,"the, in, closely, related, to"
6778,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.151515152,"the, is, in, lineage, of"
6779,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.151515152,"the, origin, of, a, and"
6780,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.151515152,"the, of, a, was, market"
6781,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.151515152,"in, the, was, and, market"
6782,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.151515152,"the, was, in, that, animal"
6783,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.151515152,"a, and, in, an, animal"
6784,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.151515152,"that, the, sars-cov-2, a, intentionally"
6785,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.151515152,"viruses, that, was, known, to, are, in, is, make, it, and, if, not, sars-cov-2, any"
6786,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.151515152,"is, that, a, progenitor, sars-cov-2"
6787,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.151515152,"are, that, not, make, if, it, was, sars-cov-2, to, and, is, any, known, viruses, in"
6788,"expended to make the simple point 

that COVID-19 had a natural origin.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.151515152,"to, the, point, that, a"
6789,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.151515152,"a, from, to, is, spillover"
6790,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.151515152,"that, is, a, naturally, occurring"
6791,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.151515152,"bat, coronavirus, with, similarity, to"
6792,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.151515152,"of, in, natural, and, the"
6793,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.151515152,"the, genome, to, coronavirus, bat"
6794,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.151515152,"the, known, to, be, of"
6795,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.151515152,"in, the, of, a, bats"
6796,"with the first case being linked to  

a seafood market","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.151515152,"with, the, to, a, market"
6797,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.151515152,"the, as, intermediate, was, a, that, virus, from, to, and"
6798,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.151515152,"the, sars-cov-2, was, to, be"
6799,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.151515152,"a, sars-cov-2, have, been, coronavirus"
6800,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.151515152,"infected, with, sars-cov-2, the, of"
6801,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.151515152,"the, sars-cov-2, coronavirus, has, from"
6802,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.151515152,"the, analysis, that, sars-cov-2, of"
6803,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.151515152,"the, of, a, and, has"
6804,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.151515152,"the, genetic, data, that, virus"
6805,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.151515152,"the, of, is, to, bat"
6806,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.151515152,"and, the, to, of, bat"
6807,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.151515152,"the, between, and, bat, is"
6808,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.151515152,"the, was, in, and, to"
6809,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.151515152,"the, was, in, from, china"
6810,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.151515152,"the, was, transmitted, to, a"
6811,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.151515152,"are, in, and, transmitted, to"
6812,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.151515152,"from, bats, to, and, the"
6813,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.151515152,"of, the, that, is, part"
6814,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.151515152,"is, that, the, as, a"
6815,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.151515152,"the, in, and, to, animals"
6816,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.151515152,"in, animals, and, to, humans"
6817,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.151515152,"that, the, is, to, sars-cov"
6818,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.151515152,"the, virus, that, and, to"
6819,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.151515152,"and, that, the, virus, to"
6820,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.151515152,"to, virus, had, and, the"
6821,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.151515152,"the, to, that, in, and"
6822,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.151515152,"virus, that, the, in, its"
6823,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.151515152,"the, to, is, that, its"
6824,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.151515152,"the, that, virus, and, to"
6825,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.151515152,"the, genus, bat, sars-like, and"
6826,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.151515152,"also, the, and, bat, cov"
6827,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.151515152,"that, and, the, virus, of"
6828,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.151515152,"viral, the, showed, that, for"
6829,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.151515152,"the, genome, to, bat, coronavirus"
6830,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.151515152,"of, to, has, sars-cov-2, the"
6831,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.151515152,"sars-cov-2, bat, to, the, of"
6832,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.151515152,"the, that, of, has, been"
6833,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.151515152,"are, the, reservoir, of, coronaviruses"
6834,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.151515152,"of, that, it, the, bat"
6835,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.151515152,"are, the, of, a, viruses"
6836,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.151515152,"the, covid-19, virus, in, bats"
6837,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.151515152,"that, from, a, transmitted, to"
6838,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.151515152,"to, from, zoonotic, a, virus"
6839,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.151515152,"is, from, a, spillover, to"
6840,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.151515152,"the, bat, all, isolated, from"
6841,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.151515152,"the, is, to, in, of"
6842,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.151515152,"of, also, to, the, in"
6843,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.151515152,"sars-cov-2, has, not, that, a"
6844,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.151515152,"the, that, sars-cov-2, humans, from"
6845,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.151515152,"animal, and, infected, the, is"
6846,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.151515152,"the, of, that, and, to"
6847,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.151515152,"the, of, and, to, that"
6848,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.151515152,"the, genome, of, with, to"
6849,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.151515152,"coronavirus, the, with, of, sars-"
6850,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.151515152,"analysis, revealed, the, from, and"
6851,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.151515152,"the, is, between, bat, and"
6852,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.151515152,"that, transmitted, from, to, a"
6853,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.151515152,"is, the, and, infected, animal"
6854,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.151515152,"the, presence, of, a, and"
6855,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.151515152,"humans, and, the, of, sars-cov-2"
6856,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.151515152,"the, and, humans, hosts, of"
6857,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.151515152,"the, most, likely, to, intermediate"
6858,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.151515152,"of, the, coronavirus, with, sars-"
6859,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.151515152,"that, the, of, with, to"
6860,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.151515152,"suggest, that, a, of, the"
6861,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.151515152,"of, a, suggest, that, the"
6862,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.151515152,"results, of, the, that, a"
6863,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.151515152,"infected, with, the, of, sars-cov-2"
6864,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.151515152,"sars-cov-2, is, a, that, naturally"
6865,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.151515152,"bats, of, and, to, the"
6866,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.151515152,"was, to, of, sars-cov-2, the"
6867,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.151515152,"hypothesis, that, was, the, of"
6868,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.151515152,"a, and, origin, of, the"
6869,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.151515152,"a, of, sars-cov-2, the, and"
6870,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.151515152,"a, of, the, sars-cov-2, and"
6871,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.151515152,"a, of, natural, and, the"
6872,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.151515152,"of, sars-cov-2, and, from, ratg13"
6873,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.151515152,"the, from, and, a, malayan"
6874,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.151515152,"sars-cov-2, and, ratg13, the, of"
6875,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.151515152,"the, and, bat, in, of"
6876,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.151515152,"a, and, of, the, in"
6877,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.151515152,"a, of, has, the, and"
6878,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.151515152,"a, of, the, presence, and"
6879,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.151515152,"the, in, zoonotic, and, of"
6880,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.151515152,"the, western, presence, of, in"
6881,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.151515152,"in, the, and, of, bat"
6882,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.151515152,"the, of, zoonotic, and, in"
6883,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.151515152,"the, a, spillover, as, to"
6884,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.151515152,"the, virus, to, and, had"
6885,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.151515152,"is, the, to, that, in"
6886,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.151515152,"is, that, the, to, sars-cov-2"
6887,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.151515152,"wiv, that, the, sars-cov-2, in"
6888,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.151515152,"that, sars-cov-2, not, to, in"
6889,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.151515152,"the, to, that, sars-cov-2, not"
6890,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.151515152,"that, 2, a, of, pangolin, with, to, the, intermediate, sars-cov-2"
6891,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.151515152,"has, found, of, sars-cov-2, in"
6892,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.151515152,"that, sars-cov-2, has, with, bat"
6893,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.151515152,"to, sars-cov-2, is, that, the"
6894,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.151515152,"has, been, that, the, of"
6895,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.151515152,"found, in, has, of, sars-cov-2"
6896,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.151515152,"sars-cov-2, in, several, species, humans"
6897,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.151515152,"and, to, was, the, that, sars-cov-2, in, a, laboratory, infect"
6898,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.151515152,"as, to, the, a, spillover"
6899,"Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.151515152,"of, susceptible, raccoon, dogs, in"
6900,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.151515152,"coronavirus, with, bat, similarity, to"
6901,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan",0.151515152,"of, raccoon, dogs, in, susceptible"
6902,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.151515152,"the, presence, of, in, western"
6903,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.151515152,"the, of, coronaviruses, are, reservoir"
6904,"expended to make the simple point 

that COVID-19 had a natural origin.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.151515152,"to, the, covid-19, a, natural"
6905,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.151515152,"the, covid-19, is, to, in"
6906,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.151515152,"the, of, bats, as, for"
6907,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.151515152,"the, to, most, likely, intermediate"
6908,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.151515152,"in, bat, coronaviruses, to, and"
6909,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.151515152,"the, to, and, that, in"
6910,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.151515152,"virus, to, the, and, for"
6911,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.151515152,"of, and, species, to, the"
6912,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.151515152,"the, similarity, of, sars-cov-2, to"
6913,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.151515152,"is, to, of, and, the"
6914,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.151515152,"the, with, that, to, of"
6915,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.151515152,"the, known, to, be, sars-cov-2"
6916,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.151515152,"of, with, december, a, to, wuhan, and, the, huanan, market"
6917,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.151515152,"to, a, virus, that, from, and, was, the, as, intermediate"
6918,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.151515152,"the, a, huanan, market, and, to, of, wuhan, december, with"
6919,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","expended to make the simple point 

that COVID-19 had a natural origin.",0.151515152,"the, that, a, point, to"
6920,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","expended to make the simple point 

that COVID-19 had a natural origin.",0.151515152,"the, covid-19, natural, to, a"
6921,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","expended to make the simple point 

that COVID-19 had a natural origin.",0.151515152,"the, covid-19, a, natural, to"
6922,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.151515152,"sars-cov-2, from, that, to, and"
6923,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.151515152,"sars-cov-2, a, an, animal, and"
6924,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.151515152,"host, sars-cov-2, and, an, animal"
6925,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.151515152,"the, virus, that, its, in"
6926,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.151515152,"the, wiv, that, in, sars-cov-2"
6927,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.151515152,"show, that, sars-cov-2, not, a"
6928,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.151515152,"genetic, data, that, the, virus"
6929,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.151515152,"of, the, that, bats, for"
6930,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.151515152,"the, is, to, that, its"
6931,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.151515152,"that, bats, the, likely, of"
6932,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.151515152,"is, that, sars-cov-2, a, progenitor"
6933,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.151515152,"in, genetic, to, sars-cov, and"
6934,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.151515152,"bats, the, more, of, than"
6935,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.151515152,"the, bats,, and, to, animals"
6936,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.151515152,"bats, the, hosts, of, and"
6937,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.151515152,"the, virus, covid-19, in, bats"
6938,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.151515152,"the, of, hosts, and, humans"
6939,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.151515152,"are, and, transmitted, to, in"
6940,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.151515152,"to, in, animals, and, humans"
6941,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.151515152,"all, isolated, from, bat, the"
6942,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.151515152,"and, the, from, bats, to"
6943,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.151515152,"of, a, the, market, was"
6944,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.151515152,"the, market, was, in, and"
6945,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.151515152,"the, of, that, and, is"
6946,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.151515152,"of, the, that, and, is"
6947,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.151515152,"the, of, and, is, that"
6948,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.151515152,"this, that, and, the, of"
6949,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.151515152,"been, from, to, a, as, likely, identified, and, bat, species"
6950,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.151515152,"sars-cov-2, genome, 96.2%, bat, cov"
6951,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.151515152,"the, analysis, our, that, virus"
6952,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.151515152,"of, to, the, and, virus"
6953,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.151515152,"that, not, in, to, sars-cov-2"
6954,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.151515152,"that, sars-cov-2, a, is, or"
6955,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.151515152,"that, sars-cov-2, has, a, not"
6956,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.151515152,"have, the, for, sars-cov, and"
6957,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.151515152,"a, that, the, was, to, infect, laboratory, and, in, sars-cov-2"
6958,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.151515152,"in, species, sars-cov-2, several, humans"
6959,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.151515152,"to, sars-cov-2, be, was, the"
6960,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.151515152,"genome, 96.2%, bat, cov, sars-cov-2"
6961,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.151515152,"sars-cov-2, to, the, bat, cov"
6962,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.151515152,"suggest, that, the, a, of"
6963,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.151515152,"and, ratg13, 96%, identity, to"
6964,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.151515152,"that, to, sars-cov-2, and, from"
6965,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.151515152,"that, sars-cov-2, and, from, viruses"
6966,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.151515152,"genome, of, sars-cov-2, with, bat"
6967,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.151515152,"other, coronaviruses, the, to, of"
6968,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.151515152,"the, to, sars-cov-2, similarity, of"
6969,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.151515152,"of, sars-cov-2, from, and, ratg13"
6970,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.151515152,"the, of, in, also, to"
6971,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.151515152,"in, the, emergence, of, sars-cov-2"
6972,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.151515152,"our, analysis, the, that, virus"
6973,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.151515152,"et, al., (2020), that, by, a, of, virus, to, the"
6974,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.151515152,"bat, sars-like, and, the, genus"
6975,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.151515152,"the, probable, bat, origin, of"
6976,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.151515152,"that, of, to, intermediate, a, pangolin, with, sars-cov-2, the, 2"
6977,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.151515152,"a, by, et, al., (2020), that, the, virus, to, of"
6978,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.151515152,"results, that, the, a, of"
6979,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.151515152,"the, of, that, sars-cov-2, is"
6980,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.151515152,"the, coronavirus, from, has, sars-cov-2"
6981,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.151515152,"sars-cov-2, from, viruses, that, and"
6982,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.151515152,"the, sars-cov-2, to, bat, cov"
6983,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.151515152,"probable, bat, origin, of, the"
6984,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.151515152,"the, sars-cov-2, with, that, bat"
6985,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.151515152,"that, bat, has, with, sars-cov-2"
6986,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.151515152,"the, sars-cov-2, bat, or, origin"
6987,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.151515152,"the, of, likely, that, bats"
6988,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.151515152,"the, of, more, than, bats"
6989,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.151515152,"the, of, that, sars-cov-2, bats"
6990,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.151515152,"sars-cov-2, the, origin, bat, or"
6991,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.151515152,"bat, cov, and, also, the"
6992,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.151515152,"the, to, sars-cov-2, and, of"
6993,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.151515152,"the, analysis, revealed, and, from"
6994,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.151515152,"the, and, sars-cov-2, in, of"
6995,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.151515152,"evidence, the, that, sars-cov-2, of"
6996,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.151515152,"the, that, sars-cov-2, and, of"
6997,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.151515152,"of, the, sars-cov-2, that, and"
6998,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.151515152,"of, sars-cov-2, the, emergence, in"
6999,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.151515152,"that, the, for, of, and"
7000,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.151515152,"the, a, from, malayan, and"
7001,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.151515152,"the, for, sars-cov, and, have"
7002,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.151515152,"for, and, that, the, of"
7003,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.151515152,"with, the, and, sars-cov-2, is"
7004,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.151515152,"sars-cov-2, the, and, to, pangolin-cov"
7005,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.151515152,"that, the, virus, and, of"
7006,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.151515152,"this, that, the, of, and"
7007,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.151515152,"the, that, in, of, bat"
7008,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.151515152,"of, the, showed, that, bats"
7009,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.151515152,"the, that, not, to, sars-cov-2"
7010,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.151515152,"that, bats, the, of, sars-cov-2"
7011,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.151515152,"virus, from, to, a, zoonotic"
7012,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.151515152,"the, animal, was, that, in"
7013,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.151515152,"that, the, most, of, is"
7014,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.151515152,"the, of, sars-cov-2, and, bat"
7015,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.151515152,"sars-cov-2, and, an, animal, host"
7016,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.151515152,"the, sars-cov-2, and, bat, of"
7017,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.151515152,"sars-cov-2, was, to, the, of"
7018,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.151515152,"the, amino, site, insertion, spike, to, a, of, in, naturally"
7019,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.151515152,"the, sars-cov-2, to, from, bats, in, of, is, be, found"
7020,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.151515152,"is, than, to, in, its"
7021,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.151515152,"the, of, sars-cov-2, to, bat"
7022,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.151515152,"the, of, sars-cov-2, and, ratg13"
7023,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.151515152,"96%, identity, to, ratg13, and"
7024,"All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.151515152,"the, that, a, intentionally, sars-cov-2"
7025,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.151260504,"the, of, a, to, live, animal, in, markets, and, animals, shenzhen, market, were, virus, at, 99.8%, was, palm"
7026,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.151260504,"to, the, sars, were, as, for, and, a, in, of, species, from, sequence, that, humans, or, found, contained"
7027,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.151260504,"for, the, of, and, were, species, that, from, contained, a, sequence, found, in, sars, or, humans, as, to"
7028,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.151260504,"in, the, animals, live, animal, markets, of, palm, at, market, virus, was, 99.8%, to, shenzhen, were, a, and"
7029,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.151162791,"the, of, to, specific, similar, closely, related, that, this, in, which, virus, its"
7030,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.151162791,"this, its, in, the, of, which, that, closely, related, to, specific, similar, virus"
7031,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.150943396,"in, bats, which, more, to, of, sars-cov-2, and"
7032,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.150943396,"the, and, sars-cov-2, is, to, bat, in, of"
7033,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.150943396,"a, of, genetic, to, sars-cov-2, the, recombination, and"
7034,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.150943396,"in, be, the, recombination, between, and, of, bat"
7035,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.150943396,"sars-cov-2, and, bat, some, coronaviruses, to, the, of"
7036,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.150943396,"sars-cov-2, is, a, virus, that, from, was, the"
7037,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.150943396,"that, a, was, the, of, sars-cov-2, is, to"
7038,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.150943396,"genome, sequence, identity, sars-cov-2, and, the, virus, bat"
7039,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.150943396,"the, sars-cov-2, and, to, of, is, in, bat"
7040,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.150943396,"to, the, of, bats, as, hosts, for, sars-cov-2"
7041,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.150943396,"the, of, to, is, likely, on, that, this"
7042,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.150943396,"species, likely, to, as, reservoir, sars-cov-2, bat, and"
7043,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.150943396,"the, as, a, of, that, from, to, humans"
7044,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.150943396,"of, the, cases, in, mid-, with, huanan, market"
7045,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.150943396,"in, an, from, of, sars-cov-2, and, the, those"
7046,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.150943396,"it, that, the, in, market, animals, as, a"
7047,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.150943396,"was, that, the, of, sars-cov-2, is, to, a"
7048,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.150943396,"a, and, were, to, of, in, the, huanan"
7049,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.150943396,"the, of, virus, is, to, that, has, and"
7050,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.150943396,"is, that, sars-cov-2, was, from, a, the, virus"
7051,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.150943396,"the, virus, is, to, that, sars-cov-2, and, a"
7052,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.150943396,"the, to, from, of, a, horseshoe, bat, (rhinolophus"
7053,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.150943396,"the, sars-cov-2, and, to, a, of, genetic, recombination"
7054,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.150943396,"the, has, a, of, that, to, by, and"
7055,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.150943396,"have, the, sars-cov-2, and, of, is, to, that"
7056,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.150943396,"the, analysis, of, which, that, sars-cov-2, was, to"
7057,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.150943396,"the, that, in, a, as, it, animals, market"
7058,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.150943396,"the, of, and, have, that, sars-cov-2, is, to"
7059,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.150943396,"the, of, coronaviruses, that, sequence, genomes, similar, to"
7060,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.150943396,"that, of, to, is, coronavirus, sars-cov-2, analysis, the"
7061,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.150943396,"that, the, of, and, novel, coronavirus, more, from"
7062,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.150943396,"virus, genome, the, bat, and, sequence, identity, sars-cov-2"
7063,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.150943396,"of, the, sequence, that, similar, to, coronaviruses, genomes"
7064,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.150943396,"a, in, the, genome, that, similar, to, of"
7065,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.150943396,"is, that, bats, sars-cov-2, as, to, a, bat"
7066,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.150943396,"the, genome, of, that, a, in, similar, to"
7067,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.150943396,"at, seafood, market, in, wuhan, the, is, to"
7068,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.150943396,"the, a, of, to, from, horseshoe, bat, (rhinolophus"
7069,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.150943396,"the, analysis, of, that, sars-cov-2, which, was, to"
7070,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.150943396,"to, sars-cov-2, is, a, virus, that, and, the"
7071,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.150943396,"the, is, of, sars-cov-2, to, a, virus, in"
7072,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.150943396,"has, been, with, that, and, human, sars-cov-2, a"
7073,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.150943396,"the, is, and, it, not, with, to, of"
7074,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.150943396,"of, the, analysis, that, sars-cov-2, coronavirus, is, to"
7075,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.150943396,"in, with, two, and, which, sars-cov-2, the, genome"
7076,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.150943396,"in, the, those, from, an, and, of, sars-cov-2"
7077,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.150943396,"in, at, with, sars-cov-2, the, amino, acid, sequence"
7078,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.150943396,"the, of, with, cases, huanan, market, in, mid-"
7079,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.150943396,"evidence, recombination, and, that, in, the, of, sars-cov-2"
7080,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.150943396,"the, of, at, that, sars-cov-2, is, a, virus"
7081,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.150943396,"in, the, of, virus, is, to, sars-cov-2, a"
7082,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.150943396,"a, closely, related, due, to, in, sars-cov-2, the"
7083,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.150943396,"sars-cov-2, reservoir, to, as, likely, and, bat, species"
7084,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.150943396,"the, two, and, which, in, with, sars-cov-2, genome"
7085,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.150943396,"the, sars-cov-2, due, to, a, closely, related, in"
7086,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.150943396,"with, bat, and, sars-cov-2, share, a, common, ancestor"
7087,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.150943396,"in, the, of, a, to, study, as, had, found, coronaviruses, genome, be, sars-related, were, and, present, that, sars, from, approximately, viral, reservoir, species, horseshoe"
7088,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.150943396,"to, the, sars, were, as, viral, be, and, a, reservoir, in, of, study, species, from, horseshoe, had, that, sars-related, coronaviruses, present, genome, found, approximately"
7089,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.150943396,"the, of, were, in, to, a, and, huanan"
7090,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.150943396,"genomic, that, the, covid-19, in, and, seafood, of"
7091,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.150943396,"on, the, of, that, to, is, this, likely"
7092,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.150943396,"the, in, of, rbd, to, that, sars-cov-2, this"
7093,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.150943396,"to, sars-cov-2, in, the, rbd, this, that, of"
7094,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.150943396,"the, that, of, covid-19, seafood, and, genomic, in"
7095,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.150943396,"the, in, sars-cov-2, with, amino, acid, sequence, at"
7096,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.150943396,"to, the, that, as, a, of, humans, from"
7097,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.150943396,"a, of, to, has, that, by, the, and"
7098,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.150943396,"that, sars-cov-2, has, been, with, human, and, a"
7099,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.150943396,"a, common, share, ancestor, with, sars-cov-2, bat, and"
7100,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.150943396,"and, sars-cov-2, in, to, bats, of, more, which"
7101,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.150943396,"to, this, that, has, the, but, be, origin"
7102,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.150943396,"is, to, at, the, seafood, market, in, wuhan"
7103,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.150943396,"sars-cov-2, is, a, bat, as, to, that, bats"
7104,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.150943396,"to, suggest, that, belongs, the, sub-genus, of, and"
7105,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.150943396,"the, of, novel, coronavirus, that, from, and, more"
7106,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.150943396,"to, the, of, sars-cov-2, bats, as, hosts, for"
7107,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.150943396,"of, suggest, that, the, belongs, to, sub-genus, and"
7108,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.150943396,"that, sars-cov-2, are, to, and, the, origin, of"
7109,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.150943396,"to, that, the, of, and, are, origin, sars-cov-2"
7110,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.150943396,"evidence, sars-cov-2, recombination, of, in, the, and, that"
7111,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.150943396,"the, between, and, be, of, in, bat, recombination"
7112,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.150943396,"to, origin, the, that, has, but, this, be"
7113,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.150943396,"is, that, sars-cov-2, a, the, of, virus, at"
7114,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.150943396,"the, of, it, is, not, to, with, and"
7115,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.150943396,"the, sars-cov-2, and, some, to, of, bat, coronaviruses"
7116,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.150684932,"also, ace2, in, a, of, and, that, the, with, as, for"
7117,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.150684932,"in, by, a, two, and, which, are, both, sars-cov-2, at, the"
7118,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.150684932,"the, and, a, in, to, that, bat, coronaviruses, are, of, sars-cov-2,"
7119,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.150684932,"a, study, from, in, that, the, is, to, of, found, bats"
7120,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.150684932,"also, a, for, as, the, of, and, in, with, that, ace2"
7121,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.150684932,"a, the, by, sars-cov-2, and, are, at, two, in, which, both"
7122,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.150684932,"bats, of, and, a, to, that, severe, in, acute, respiratory, syndrome"
7123,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.150684932,"not, only, species,, a, of, but, some, and, to, from, usually"
7124,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.150684932,"but, a, from, to, usually, not, only, of, species,, and, some"
7125,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.150684932,"study, that, of, from, bats, to, is, a, found, in, the"
7126,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.150684932,"to, severe, acute, respiratory, syndrome, in, bats, of, and, that, a"
7127,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.150684932,"the, of, and, bat, coronaviruses, that, a, in, are, to, sars-cov-2,"
7128,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.150442478,"the, southern, of, china, a, to, live, animal, in, wet, markets, and, various, were, virus, at, palm"
7129,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.150442478,"at, to, a, palm, animal, in, the, virus, wet, markets, southern, china, live, were, of, and, various"
7130,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.15,"viruses, are, closely, related, to, sars-cov-2"
7131,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.15,"are, sars-cov-2, very, to, a, bat"
7132,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.15,"are, many, and, a, which, related, to, in, human"
7133,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.15,"of, viruses, are, a, species, in"
7134,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.15,"the, are, species, of, bats, and"
7135,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.15,"sequences, and, similar, in, many, such"
7136,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.15,"the, of, sars-cov-2, to, be, is, and, between, some"
7137,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.15,"the, was, a, that, bat, to"
7138,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.15,"that, the, identity, to, of, bat"
7139,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.15,"the, genome, sars-cov-2, to, human, bat"
7140,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.15,"in, many, such, sequences, similar, and"
7141,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.15,"bat, of, sars-cov-2, genome, the, in"
7142,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.15,"of, sars-cov-2, are"
7143,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.15,"sars-cov-2, are, of"
7144,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.15,"sars-cov-2, are, to"
7145,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.15,"to, are, sars-cov-2"
7146,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",Originating from reservoir of bat,0.15,"from, reservoir, of"
7147,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.15,"to, humans, between, and, be, the"
7148,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.15,"the, of, that, bats, as, its"
7149,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.15,"a, is, the, to, that, in, virus, and, thus"
7150,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.15,"the, virus, as, a, coronavirus, that, with, and, to"
7151,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.15,"a, the, is, virus, thus, and, in, that, to"
7152,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.15,"the, virus, human, in, to, and"
7153,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.15,"to, virus, had, and, was, the"
7154,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.15,"the, discovered, to, that, in, and"
7155,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.15,"were, to, wet, animal, market, in"
7156,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",Bats are likely reservoir hosts for SARS-CoV-2,0.15,"sars-cov-2, are, bats"
7157,"S1/S2 cleavage sites of coronaviruses are frequently modi- 

fied by insertions or deletions (indels) during evolution",zoonotic origins of SARS-CoV-2 by natural evolution,0.15,"of, by, evolution"
7158,COVID-19 is a zoonotic virus,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.15,"is, a, zoonotic"
7159,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.15,"sars-cov-2, is, a, with, to, the"
7160,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.15,"of, the, sars-cov-2, lineage, in, is"
7161,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.15,"the, and, of, bat, that, to"
7162,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.15,"to, sars-cov-2, is, that, and, the"
7163,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.15,"the, is, that, to, of, and"
7164,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.15,"to, that, the, of, and, is"
7165,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.15,"sars-cov-2, is, to, the, with, bat"
7166,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.15,"with, the, and, to, that, sars-cov-2, is, of, bat"
7167,Bats are likely reservoir hosts for SARS-CoV-2,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.15,"bats, are, sars-cov-2"
7168,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.15,"bats, to, be, the, of, pangolins"
7169,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.15,"a, that, the, and, which, by"
7170,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.15,"to, humans, from, the, of, sars-cov-2"
7171,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.15,"the, that, sars-cov-2, natural, from, a"
7172,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.15,"that, the, from, a, to, humans"
7173,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.15,"of, lineage, a, at, the, from"
7174,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.15,"of, the, are, viruses, from, a"
7175,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.15,"of, that, to, the, bat, coronaviruses,"
7176,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.15,"that, the, market, animals, to, and"
7177,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.15,"that, the, and, to, through, of"
7178,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.15,"that, sars-cov-2, the, of, and, to"
7179,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.15,"that, the, a, market, in, to"
7180,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.15,"a, origin, of, at, the, in"
7181,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.15,"a, at, the, of, from, lineage"
7182,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.15,"more, than, the, were, to, re-"
7183,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.15,"than, the, huanan, and, that, was"
7184,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.15,"that, was, and, in, at, market"
7185,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.15,"that, the, was, and, in, sars-cov-2"
7186,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.15,"the, in, market, that, was, at"
7187,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.15,"the, in, that, likely, sars-cov-2, than"
7188,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.15,"re-, were, more, to, the, than"
7189,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.15,"the, huanan, was, than, that, and"
7190,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.15,"the, were, more, to, that, and"
7191,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.15,"of, cases, covid-19, to, and, the, huanan, were, earliest"
7192,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.15,"it, that, the, as, to, a"
7193,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.15,"that, covid-19, originated, in, to, wuhan"
7194,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.15,"the, of, and, that, sars-cov-2, is, an, was, to"
7195,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.15,"was, that, the, in, have, market, live, animals, were, or, a, of"
7196,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.15,"was, that, the, to, a, bat"
7197,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.15,"a, coronavirus, as, the, virus, and, with, that, to"
7198,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.15,"a, virus, that, with, the, bat"
7199,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.15,"the, similarity, to, bat, that, as"
7200,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.15,"studies, that, the, a, to, and"
7201,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.15,"the, of, to, as, intermediate, host"
7202,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.15,"the, huanan, market, that, in, of, cases, were, to, and, with, a"
7203,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.15,"indicates, a, that, the, of, and"
7204,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.15,"that, the, virus, had, of, to"
7205,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.15,"the, sars-cov-2, that, and, is, to"
7206,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","Bats have been reported as being the rich source of 

coronaviruses",0.15,"the, source, of"
7207,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.15,"with, the, and, sars-cov-2, to, of"
7208,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.15,"similar, of, sars-cov-2, and, from, their"
7209,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.15,"sars-cov-2, and, exhibit, to, the, of"
7210,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.15,"the, of, virus, to, by, genetic"
7211,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.15,"that, the, of, sars-cov-2, and, has"
7212,"the close relation  

between SARS coronavirus and 2019-nCoV","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.15,"the, between, and"
7213,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.15,"of, and, bat, possible, between, the"
7214,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.15,"to, and, of, is, possible, bat"
7215,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.15,"that, was, the, of, sars-cov-2, and, is, to, an"
7216,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.15,"the, is, to, and, that, animal"
7217,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.15,"was, and, in, a, market, china"
7218,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.15,"in, from, bats, to, and, the"
7219,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.15,"a, the, was, to, and, in"
7220,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.15,"genetic, sequencing, has, to, covid-19, in"
7221,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.15,"in, to, covid-19, genetic, sequencing, has"
7222,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.15,"the, of, is, at, that, virus"
7223,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.15,"more, the, were, to, and, that"
7224,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.15,"in, were, to, and, the, humans"
7225,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.15,"the, in, to, that, virus, jumped"
7226,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.15,"the, and, that, is, animal, to"
7227,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.15,"the, is, similar, to, animal, sars-cov"
7228,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.15,"to, and, is, that, similar, in"
7229,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.15,"bat, cov, and, the, into, with"
7230,COVID-19 is a zoonotic virus,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.15,"is, zoonotic, virus"
7231,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.15,"is, because, and, to, the, that"
7232,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.15,"the, of, is, to, that, virus"
7233,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.15,"a, sequence, identity, and, sars-cov, with, the, of, bat"
7234,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.15,"that, the, of, market, in, was, or, live, animals, were, have, a"
7235,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.15,"genome, the, to, bat, human, sars-cov-2"
7236,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.15,"the, reported, to, has, been, of"
7237,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.15,"the, to, sars-cov-2"
7238,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.15,"the, sars-cov-2, to"
7239,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.15,"that, the, sars-cov-2, and, sars-cov, receptor, which, ace2, a"
7240,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.15,"the, is, similar, to, sars-cov, animal"
7241,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.15,"from, ,, the, that, it, human"
7242,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.15,"a, viruses, are, the, of, from"
7243,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.15,"of, that, is, most, bat, and"
7244,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.15,"the, to, it, is, for, humans"
7245,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.15,"the, sars-cov-2, to, humans, from, bats"
7246,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.15,"the, to, sars-cov-2, isolated, from, bat"
7247,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.15,"the, from, all, sars-cov-2, to, bat"
7248,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.15,"of, the, isolated, in, from, is"
7249,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.15,"the, to, in, human, virus, and"
7250,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.15,"most, virus, in"
7251,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.15,"that, and, be, intermediate, sars-cov-2, transmission, to, humans, between"
7252,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.15,"to, humans, through, an, intermediate, animal"
7253,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.15,"of, to, the, that, had, virus"
7254,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.15,"the, of, to, that, features, virus"
7255,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.15,"bat, virus, strain, genome, of, with"
7256,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",COVID-19 is a zoonotic virus,0.15,"a, is, zoonotic"
7257,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",COVID-19 is a zoonotic virus,0.15,"is, virus, a"
7258,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",COVID-19 is a zoonotic virus,0.15,"is, virus, zoonotic"
7259,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",COVID-19 is a zoonotic virus,0.15,"a, covid-19, is"
7260,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.15,"coronavirus, to, is, similar, sars-cov-2, the"
7261,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.15,"that, the, of, to, bat, identity"
7262,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.15,"the, that, sars-cov-2, a, from, natural"
7263,"natural selection in humans  

following zoonotic transfer","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.15,"in, zoonotic, transfer"
7264,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.15,"the, sars-, cov-2, bat, is, that"
7265,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.15,"to, the, that, a, humans, from"
7266,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.15,"the, market, animals, that, to, and"
7267,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.15,"in, a, that, the, to, market"
7268,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.15,"studies, the, to, and, that, a"
7269,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.15,"at, market, was, that, in, and"
7270,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.15,"and, was, a, market, in, china"
7271,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.15,"that, the, of, identical, to, sars-cov"
7272,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.15,"a, the, sars-cov, of, bat, and, sequence, identity, with"
7273,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.15,"that, the, of, sars-cov-2, and, novel"
7274,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.15,"the, to, bats, pangolins, of, be"
7275,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.15,"the, most, likely, are, of, bats"
7276,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.15,"provide, for, that, the, of, sars-cov-2"
7277,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","Bats are natural hosts of many of the known  

coronaviruses",0.15,"the, natural, of"
7278,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.15,"a, that, the, sars-cov-2, ace2, receptor, and, which, sars-cov"
7279,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.15,"the, pangolin, intermediate"
7280,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.15,"has, the, sequence, which, with, sars-cov-2"
7281,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.15,"of, has, been, that, the, a"
7282,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.15,"it, is, that, the, to, a"
7283,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.15,"the, to, was, in, of, a"
7284,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.15,"that, the, of, a, was, to"
7285,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.15,"coronavirus, to, similar, at, the, genome"
7286,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.15,"of, to, a, genome, was, in"
7287,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.15,"sars-cov-2, isolated, from, to, bat, the"
7288,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.15,"a, in, the, was, to, of"
7289,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.15,"bat, to, an, in, the, of"
7290,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.15,"that, the, for, a, of, and"
7291,"Bats are natural hosts of many of the known  

coronaviruses","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.15,"natural, of, the"
7292,Coronaviruses account for over 30% of the world’s viruses.,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.15,"for, of, the"
7293,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.15,"been, in, the, of, natural, has"
7294,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","this one jumped from bats origin  

into humans",0.15,"this, bats, origin"
7295,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.15,"virus, most, in"
7296,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.15,"the, assessed, a, from, host, as"
7297,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.15,"that, the, of, sars-cov-2, is, to"
7298,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.15,"the, to, had, virus, and, was"
7299,The FCS of SARS-CoV-2 was not bioengineered—full stop.,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.15,"the, sars-cov-2, not"
7300,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.15,"in, the, of, an, intermediate, host, a, found, that, from, humans, to"
7301,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.15,"the, two, of, were, with, in"
7302,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.15,"of, genome, virus, with, bat, strain"
7303,"According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.15,"to, the, sars-cov-2"
7304,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.15,"is, to, sars-cov-2"
7305,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.15,"that, a, origin, of, the, is"
7306,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.15,"and, the, from, bats, to, in"
7307,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.15,"the, were, to, in, and, humans"
7308,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.15,"the, has, which, sequence, with, sars-cov-2"
7309,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.15,"at, which, has, the, with, level"
7310,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.15,"between, humans, and, that, transmission, sars-cov-2, to, intermediate, be"
7311,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.15,"the, sars-cov-2, was, that, in, and"
7312,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.15,"and, the, was, to, a, in"
7313,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.15,"the, to, be, amino, acid, rbd"
7314,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.15,"the, between, sars-cov-2, and, some, to, be, of, is"
7315,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.15,"to, humans, for, the, it, is"
7316,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.15,"for, between, and, the, of, sars-cov-2"
7317,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.15,"the, assessed, as, a, host, from"
7318,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.15,"a, the, that, was, to, of"
7319,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.15,"the, at, market, was, that, in"
7320,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.15,"that, the, of, sars-cov-2, and, has, been, from, bats"
7321,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.15,"the, closely, related, to, sars-cov-2, of"
7322,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.15,"sars-cov-2, a, natural, in, zoonotic, or"
7323,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.15,"bats, are, the, most, likely, of"
7324,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",Coronaviruses account for over 30% of the world’s viruses.,0.15,"the, of, for"
7325,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",Coronaviruses account for over 30% of the world’s viruses.,0.15,"the, for, of"
7326,"Bats are natural hosts of many of the known  

coronaviruses","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.15,"bats, of, the"
7327,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.15,"the, to, that, discovered, in, and"
7328,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.15,"discovered, that, the, sars-cov-2, in, bat"
7329,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.15,"in, the, closely, related, to, virus"
7330,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.15,"the, to, in, an, of, bat"
7331,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.15,"are, viruses, in, a, of, species"
7332,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.15,"the, of, possible, between, bat, and"
7333,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.15,"the, sars-cov-2, coronavirus, is, similar, to"
7334,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.15,"coronavirus, the, genome, similar, to, at"
7335,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.15,"by, a, with, similar, to, and, are, the, sars-cov-2"
7336,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.15,"sars-cov-2, are, closely, related, to, viruses"
7337,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.15,"the, of, sars-cov-2, to, closely, related"
7338,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.15,"the, and, are, of, that, to"
7339,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.15,"the, is, to, that, of, and"
7340,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.15,"the, and, to, that, is, of, are, sars-, cov-2"
7341,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","This suggests that the BANAL series may be able to directly infect  

humans.",0.15,"this, suggests, the"
7342,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.15,"in, these, were, to, through, animal"
7343,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.15,"of, genetic, to, by, the, virus"
7344,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.15,"may, a, recombination, with, to, and, are, the, sars-cov-2"
7345,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.15,"the, as, a, species, of, that, likely, from, to, humans, civets, and"
7346,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.15,"that, of, from, to, humans, an, intermediate, host, a, found, in, the"
7347,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.15,"an, had, to, a, as, sampled, from, in, for, the, or, antibodies., across, sars, were, zoonotic, of, several, and, species, horseshoe"
7348,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.15,"to, the, sars, were, as, for, several, zoonotic, and, a, in, of, sampled, across, species, from, horseshoe, had, antibodies., an, or"
7349,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.15,"that, the, of, cases, were, in, to, with, a, and, huanan, market"
7350,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.15,"of, the, earliest, covid-19, cases, were, to, huanan, and"
7351,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.15,"the, of, covid-19, huanan, seafood, market"
7352,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.15,"to, the, with, a, sars-cov-2, is"
7353,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.15,"the, sars-cov-2, with, to, its, natural"
7354,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.15,"the, in, and, to, unknown, of"
7355,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.15,"natural, zoonotic, sars-cov-2, or, a, in"
7356,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.15,"the, virus, a, that, with, bat"
7357,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.15,"the, discovered, that, sars-cov-2, bat, in"
7358,"ARS-CoV-2 is a 

natural virus, not a lab-created one.","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.15,"is, a, not"
7359,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.15,"that, is, the, most, of, sars-cov-2"
7360,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","atural  

selection in an animal host before zoonotic  

transfer;",0.15,"in, animal, before"
7361,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","natural selection in humans  

following zoonotic transfer",0.15,"zoonotic, in, humans"
7362,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.15,"the, of, that, its, as, bats"
7363,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.15,"the, as, that, bat, similarity, to"
7364,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.15,"that, the, sars-, cov-2, bat, is"
7365,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.15,",, it, that, the, human, from"
7366,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.15,"the, to, that, virus, in, jumped"
7367,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.15,"the, of, sars-cov-2, identical, with, and"
7368,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","In the 

case of MERS, dromedaries were the principal host.",0.15,"the, of, in"
7369,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.15,"of, a, analysis, that, the, bat"
7370,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.15,"the, of, showed, identity, to, bats"
7371,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.15,"through, the, that, to, and, of"
7372,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.15,"that, covid-19, originated, in, wuhan, to"
7373,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.15,"of, unknown, in, and, to, the"
7374,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.15,"that, bats, the, hosts, of, and"
7375,"natural selection in humans  

following zoonotic transfer","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.15,"in, humans, zoonotic"
7376,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",Bats are hosts of many coronaviruses,0.15,"coronaviruses, of, bats"
7377,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",Bats are hosts of many coronaviruses,0.15,"of, coronaviruses, bats"
7378,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.15,"humans, to, through, an, intermediate, animal"
7379,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.15,"to, in, through, these, were, animal"
7380,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.15,"to, bat, coronaviruses,, that, the, of"
7381,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.15,"and, that, is, most, of, bat"
7382,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.15,"the, of, two, were, in, with"
7383,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.15,"the, covid-19, huanan, seafood, market, of"
7384,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.15,"the, of, has, been, reported, to"
7385,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.15,"the, be, to, between, humans, and"
7386,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.15,"the, sars-cov-2, is, in, lineage, of"
7387,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.15,"the, of, in, is, isolated, from"
7388,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.15,"indicates, that, the, of, a, and"
7389,COVID-19 is a zoonotic virus,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.15,"covid-19, is, a"
7390,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.15,"the, of, and, civets, species, that, from, a, likely, humans, as, to"
7391,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.15,"to, lab, origin, the, that, has, been, by, wiv"
7392,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","ARS-CoV-2 is a 

natural virus, not a lab-created one.",0.15,"is, not, a"
7393,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.15,"that, sars-cov-2, to, a, bat, it"
7394,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.15,"to, that, sars-cov-2, not, directly, from"
7395,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.15,"the, that, a, of, has, been"
7396,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.15,"the, not, sars-cov-2"
7397,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.15,"the, that, of, origin, is, a"
7398,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.15,"and, a, hypothesis, the, origin, of"
7399,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.15,"the, natural, of, in, has, been"
7400,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.15,"the, wiv, has, been, lab, by, that, to, origin"
7401,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.15,"sars-cov-2, natural, its, with, to, the"
7402,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.15,"similar, from, and, their, of, sars-cov-2"
7403,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.15,"this, that, natural, and, the, of"
7404,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.15,"that, pangolins, be, hosts, for, sars-cov-2"
7405,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.15,"all, sars-cov-2, from, to, bat, the"
7406,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.15,"sars-cov-2, are, to, bat, a, very"
7407,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.15,"the, that, a, as, it, to"
7408,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.15,"the, is, that, to, a, it"
7409,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.15,"the, that, sars-cov-2, is, a, for"
7410,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.15,"analysis, that, the, of, a, bat"
7411,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.15,"the, sars-cov-2, bat, in, of, genome"
7412,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.15,"a, in, genome, was, to, of"
7413,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.15,"(2020), 2, a, of, to, and, the, for, sars-cov-2"
7414,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.15,"by, a, with, and, are, similar, to, sars-cov-2, the"
7415,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.15,"are, a, to, recombination, may, with, sars-cov-2, the, and"
7416,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.15,"and, (2020), a, of, sars-cov-2, the, for, to, 2"
7417,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.15,"(2020), that, the, of, and, this, novel, coronavirus, rather"
7418,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.15,"of, has, that, sars-cov-2, the, and"
7419,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.15,"of, the, sars-cov-2, that, and, novel"
7420,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.15,"sars-cov-2, from, of, bats, the, and, has, been, that"
7421,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.15,"the, of, and, (2020), that, this, novel, coronavirus, rather"
7422,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.15,"is, that, the, and, because, to"
7423,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.15,"the, sars-cov-2, with, is, to, bat"
7424,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.15,"the, of, sars-cov-2, with, that, and, is, to, bat"
7425,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.15,"the, of, and, are, to, is, that, sars-, cov-2"
7426,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.15,"this, the, pangolin"
7427,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.15,"the, sars-cov-2, likely, than, that, in"
7428,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.15,"the, of, sars-cov-2, cluster, bat, pangolin"
7429,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.15,"with, bat, cov, and, into, the"
7430,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.15,"the, hypothesis, of, origin, a, and"
7431,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.15,"the, sars-cov-2, cluster, bat, pangolin, of"
7432,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.15,"the, of, sars-cov-2, to, is, and"
7433,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.15,"the, of, with, identical, and, sars-cov-2"
7434,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.15,"that, of, sars-cov-2, the, provide, for"
7435,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.15,"the, of, sars-cov-2, for, and, between"
7436,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.15,"that, sars-cov-2, the, of, we, recombination"
7437,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.15,"the, and, that, for, a, of"
7438,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.15,"that, the, bats, and, hosts, of"
7439,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.15,"this, that, natural, the, of, and"
7440,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.15,"the, of, bat-sl-cov-2, to, that, sars-cov-2"
7441,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.15,"that, sars-cov-2, not, directly, from, to"
7442,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.15,"the, that, sars-cov-2, bat-sl-cov-2, of, to"
7443,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.15,"is, at, that, the, virus, of"
7444,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.15,"is, that, the, virus, of, to"
7445,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.15,"that, the, virus, features, of, to"
7446,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.15,"we, recombination, that, the, of, sars-cov-2"
7447,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.15,"the, of, sars-cov-2, is, most, that"
7448,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.15,"is, that, the, for, sars-cov-2, a"
7449,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.15,"the, of, with, and, is, to"
7450,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.15,"human, and, are, related, to, in, a, which, many"
7451,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.15,"has, at, the, level, which, with"
7452,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.15,"amino, acid, the, rbd, be, to"
7453,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.15,"is, to, of, possible, bat, and"
7454,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.15,"is, similar, to, and, that, in"
7455,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.15,"the, intermediate, host, to, of, as"
7456,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.15,"exhibit, to, and, the, of, sars-cov-2"
7457,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.15,"sars-cov-2, the, of, and, similarity, to"
7458,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.149425287,"in, the, of, virus, for, not, to, that, sars-cov-2, has, human, and, a"
7459,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.149425287,"sars-cov-2, of, has, for, to, human, a, virus, that, not, in, and, the"
7460,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.149350649,"the, live, to, in, markets, a, for, spread, of, as, one, large, reservoir, with, sars, that, infected, were, by, animal, and, palm, market"
7461,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.149350649,"as, a, of, the, market, palm, animal, and, live, markets, were, by, in, to, spread, sars, with, large, infected, for, one, that, reservoir"
7462,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.149253731,"sars-cov, and, a, the, natural, of, human, with, palm, as"
7463,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.149253731,"a, the, sars-cov, palm, as, natural, of, and, with, human"
7464,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.149253731,"that, of, to, is, a, in, with, sars-cov-2, the, 2"
7465,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.149253731,"in, the, of, 2, is, to, that, sars-cov-2, with, a"
7466,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.149253731,"a, by, genome, was, at, in, the, closely, related, to"
7467,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.149253731,"the, of, closely, related, virus, to, by, genetic, is, sars-related"
7468,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.149253731,"the, of, closely, related, is, by, virus, to, sars-related, genetic"
7469,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.149253731,"the, and, a, in, to, these, bat, coronaviruses, are, common"
7470,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.149253731,"suggests, that, the, virus, in, and, to, humans, intermediate, of"
7471,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.149253731,"the, of, and, intermediate, that, virus, in, suggests, humans, to"
7472,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.149253731,"evidence, that, the, of, bats, and, pangolins, have, for, are"
7473,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.149253731,"was, in, by, a, closely, related, to, at, the, genome"
7474,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.149253731,"evidence, that, bats, are, the, of, and, have, pangolins, for"
7475,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.149253731,"are, a, coronaviruses, to, common, in, these, the, bat, and"
7476,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.149068323,"among, with, the, and, for, of, a, to, however,, officials, that, were, infections, in, sars, live, animal, palm, infected, by, contrast,, at, market, majority"
7477,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.149068323,"a, of, the, market, palm, at, animal, and, live, were, by, officials, in, to, sars, with, however,, infected, for, that, contrast,, majority, infections, among"
7478,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.14893617,"viruses, closely, related, to, and, a, which"
7479,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.14893617,"sars-cov-2, and, bat, pangolin, to, viruses, in"
7480,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.14893617,"the, into, humans,, which, to, of, and"
7481,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.14893617,"the, of, with, sars-cov, and, to, bat"
7482,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.14893617,"a, in, the, with, was, to, of"
7483,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.14893617,"a, of, sars-cov-2, be, coronavirus, origin, that"
7484,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.14893617,"the, of, that, sars-cov-2, is, was, to"
7485,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.14893617,"the, genome, of, is, to, bat, sars-cov"
7486,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.14893617,"that, sars-cov-2, to, and, the, origin, of"
7487,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.14893617,"been, bats, and, are, the, of, most"
7488,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.14893617,"that, the, virus, in, and, to, a"
7489,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.14893617,"of, the, covid-19, in, to, were, market"
7490,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.14893617,"bats, are, the, most, been, of, and"
7491,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.14893617,"the, natural, to, that, virus, animals, and"
7492,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.14893617,"in, the, is, identical, to, at, which"
7493,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.14893617,"to, the, of, and, into, humans,, which"
7494,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.14893617,"to, with, the, of, and, sars-cov, bat"
7495,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.14893617,"that, of, with, to, and, the, sars-cov-2"
7496,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.14893617,"the, of, that, as, evidence, to, hypothesis"
7497,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.14893617,"a, from, animals, to, humans, the, spillover"
7498,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.14893617,"the, was, a, and, to, on, with"
7499,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.14893617,"the, of, this, that, virus, been, in"
7500,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.14893617,"sars-cov-2, is, a, virus, that, to, the"
7501,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.14893617,"the, is, to, sars-cov-2, that, pangolin, virus"
7502,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.14893617,"that, pangolin, and, the, virus, for, of"
7503,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.14893617,"the, of, from, pangolins, with, and, sars-cov-2"
7504,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.14893617,"of, the, sars-cov-2, pangolins, from, their, and"
7505,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.14893617,"circulating, antibodies, with, the, protein, of, to"
7506,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.14893617,"was, that, the, of, sars-cov-2, is, to"
7507,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.14893617,"the, that, sars-cov-2, evolutionary, of, and, to"
7508,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.14893617,"a, and, the, virus, from, in, china"
7509,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.14893617,"a, the, to, that, in, virus, and"
7510,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.14893617,"animals, that, virus, natural, to, and, the"
7511,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.14893617,"a, in, the, with, that, was, of"
7512,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.14893617,"that, the, sars-cov-2, and, is, which, same"
7513,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.14893617,"also, that, the, sars-cov-2, and, is, same"
7514,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.14893617,"that, sars-cov-2, also, to, and, a, the"
7515,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.14893617,"the, of, more, than, 80%, to, sars-cov"
7516,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.14893617,"genetic, and, have, that, is, of, bat"
7517,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.14893617,"genetic, and, that, of, the, virus, is"
7518,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.14893617,"of, that, the, virus, to, bat, and"
7519,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.14893617,"have, genetic, and, of, is, that, bat"
7520,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.14893617,"from, humans, the, a, animals, to, spillover"
7521,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.14893617,"a, the, that, sars-cov-2, originated, from, laboratory"
7522,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.14893617,"and, the, virus, from, a, in, china"
7523,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.14893617,"a, of, bat, from, in, china, sars-cov-2"
7524,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.14893617,"evidence, to, the, hypothesis, that, as, of"
7525,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.14893617,"the, of, is, to, that, mutations, virus"
7526,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.14893617,"a, of, the, in, was, to, with"
7527,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.14893617,"was, that, the, with, in, a, of"
7528,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.14893617,"in, the, of, to, that, with, a"
7529,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.14893617,"ratg13, the, sequence, of, which, rbd, sars-cov-2"
7530,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.14893617,"of, analysis, that, the, virus, to, which"
7531,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.14893617,"the, of, a, human, as, well, and"
7532,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.14893617,"the, of, it, bats, as, for, its"
7533,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.14893617,"in, the, for, it, sars-cov-2, with, a"
7534,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.14893617,"a, for, sars-cov-2, it, with, the, in"
7535,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.14893617,"that, the, of, with, to, human, than"
7536,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.14893617,"genome, sequences, from, in, the, of, and"
7537,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.14893617,"been, by, the, of, origin, has, is"
7538,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.14893617,"the, of, sequence, which, sars-cov-2, ratg13, rbd"
7539,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.14893617,"the, sars-cov-2, with, amino, acid, sequence, at"
7540,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.14893617,"at, the, sequence, amino, acid, with, sars-cov-2"
7541,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.14893617,"in, the, amino, acid, s, protein, viral"
7542,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.14893617,"a, was, that, the, sars-cov-2, and, to"
7543,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.14893617,"the, of, were, to, market, in, covid-19"
7544,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.14893617,"in, the, of, is, to, sars-cov-2, virus"
7545,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.14893617,"bats, and, the, southeast, or, in, china"
7546,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.14893617,"southeast, and, southern, are, bat, in, the"
7547,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.14893617,"and, of, in, an, important, the, to"
7548,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.14893617,"the, are, bat, in, southern, and, southeast"
7549,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.14893617,"that, of, similar, to, and, are, the"
7550,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.14893617,"the, of, than, to, that, with, human"
7551,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.14893617,"and, closely, related, to, a, which, viruses"
7552,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.14893617,"on, the, was, a, with, and, to"
7553,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.14893617,"a, of, in, and, to, which, the"
7554,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.14893617,"to, sars-cov-2, is, a, virus, that, the"
7555,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.14893617,"the, that, sars-cov-2, is, a, virus, for"
7556,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.14893617,"a, and, to, of, which, in, the"
7557,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.14893617,"the, of, bats, as, for, it, its"
7558,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.14893617,"pangolins, from, and, with, the, of, sars-cov-2"
7559,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.14893617,"seafood, market, in, china, the, is, to"
7560,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.14893617,"pangolins, from, and, their, the, of, sars-cov-2"
7561,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.14893617,"the, of, sars-cov-2, and, been, from, viruses"
7562,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.14893617,"amino, acid, in, the, s, protein, viral"
7563,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.14893617,"the, or, bats, in, southeast, and, china"
7564,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.14893617,"a, of, the, that, scientific, data, virus"
7565,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.14893617,"of, scientific, data, the, that, a, virus"
7566,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.14893617,"the, genetic, and, of, virus, is, that"
7567,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.14893617,"the, of, human, a, and, as, well"
7568,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.14893617,"the, of, has, been, origin, is, by"
7569,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.14893617,"the, is, to, in, seafood, market, china"
7570,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.14893617,"the, analysis, of, which, that, to, virus"
7571,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.14893617,"and, to, an, important, in, the, of"
7572,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.14893617,"the, of, and, are, similar, to, that"
7573,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.14893617,"that, bats, are, the, hosts, for, and"
7574,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.14893617,"viruses, of, the, sars-cov-2, been, from, and"
7575,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.14893617,"this, that, sars-cov-2, has, the, bats, of"
7576,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.14893617,"and, sars-cov-2, to, bat, pangolin, in, viruses"
7577,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.14893617,"that, the, sars-cov-2, same, and, which, is"
7578,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.14893617,"that, the, sars-cov-2, also, same, and, is"
7579,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.14893617,"the, sequences, of, from, and, in, genome"
7580,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.14893617,"the, origin, of, to, that, and, sars-cov-2"
7581,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.14893617,"a, that, the, sars-cov-2, also, and, to"
7582,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.14893617,"the, sars-cov-2, and, of, genome, to, that"
7583,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.14893617,"are, the, and, that, bats, hosts, for"
7584,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.14893617,"the, virus, for, of, that, pangolin, and"
7585,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.14893617,"that, of, pangolin, virus, and, the, for"
7586,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.14893617,"the, of, and, that, sars-cov-2, to, evolutionary"
7587,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.14893617,"is, identical, at, the, to, which, in"
7588,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.14893617,"to, sars-cov-2, is, virus, that, the, pangolin"
7589,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.14893617,"the, is, that, virus, to, of, mutations"
7590,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.14893617,"the, is, of, sars-cov-2, to, virus, in"
7591,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.14893617,"the, of, that, sars-cov-2, to, cov, pangolin"
7592,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.14893617,"that, the, of, sars-cov-2, this, has, bats"
7593,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.14893617,"this, of, the, in, that, been, virus"
7594,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.14893617,"sars-cov-2, is, a, virus, that, the, for"
7595,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.14893617,"the, that, sars-cov-2, originated, from, a, laboratory"
7596,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.14893617,"a, sars-cov-2, of, from, bat, in, china"
7597,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.14893617,"be, that, a, origin, of, sars-cov-2, coronavirus"
7598,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.14893617,"to, circulating, antibodies, with, the, protein, of"
7599,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.148648649,"bats, as, the, recombination, to, be, with, of, thus, for, and"
7600,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.148648649,"the, china, have, a, to, in, and, animals, market, virus, at"
7601,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.148648649,"bats, for, as, the, recombination, of, thus, and, be, with, to"
7602,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.148648649,"in, the, of, a, that, virus, to, human, and, more, than"
7603,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.148648649,"and, amino, with, sars-cov-2, other, intermediate, hosts, to, be, in, the"
7604,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.148648649,"in, the, of, virus, more, than, to, that, human, and, a"
7605,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.148648649,"have, the, virus, in, and, to, animals, at, a, market, china"
7606,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.148648649,"and, be, intermediate, hosts, sars-cov-2, to, other, the, amino, in, with"
7607,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.148514851,"of, cases, with, december, 2019,, had, a, history, exposure, to, and, the, huanan, market, were"
7608,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.148514851,"in, viruses, are, into, different, clusters, and, together, with, bat, cluster, this, that, the, is"
7609,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.148514851,"a, the, huanan, with, december, 2019,, and, market, of, cases, were, to, had, history, exposure"
7610,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.148514851,"and, the, bat, clusters, viruses, are, cluster, together, different, with, that, into, this, in, is"
7611,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.148148148,"the, or, of, bats, in, southeast, asia, and"
7612,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.148148148,"bats, and, pangolins, the, from, southeast, or, in"
7613,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.148148148,"are, of, a, viruses"
7614,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.148148148,"sars-cov, in, and, to"
7615,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.148148148,"genome, sars-cov-2, identical, to"
7616,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.148148148,"sars-cov-2, is, identical, to"
7617,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.148148148,"the, to, have, it, would, that, been, of"
7618,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.148148148,"is, from, any, previously"
7619,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.148148148,"cov, sequence, bat, that, the, of, sars-cov-2, sars-cov"
7620,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.148148148,"are, viruses, a, of"
7621,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.148148148,"of, the, are, natural"
7622,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.148148148,"the, of, are, bats, and, can, be, to"
7623,"Malayan pangolins (Manis javanica)  

illegally imported into Guangdong province  

contain coronaviruses similar to SARS- 

CoV-22","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.148148148,"malayan, pangolins, (manis, javanica)"
7624,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.148148148,"in, the, of, it, is, to, that, this"
7625,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.148148148,"be, the, of, and"
7626,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.148148148,"sars-cov-2, the, of, spillover"
7627,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.148148148,"the, spillover, transmission, and"
7628,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.148148148,"the, to, sars-cov-2, and"
7629,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.148148148,"be, of, and, the"
7630,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.148148148,"bats, be, the, of"
7631,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.148148148,"the, of, be, natural"
7632,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.148148148,"and, be, the, of, sars-, bats, natural, hosts"
7633,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.148148148,"and, bats, the, of"
7634,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.148148148,"and, important, the, of"
7635,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",Bats are likely reservoir hosts for SARS-CoV-2,0.148148148,"sars-cov-2, bats, hosts, for"
7636,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",Bats are likely reservoir hosts for SARS-CoV-2,0.148148148,"hosts, for, sars-cov-2, are"
7637,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.148148148,"sars-cov-2, from, a, is"
7638,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.148148148,"the, is, considered, to"
7639,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.148148148,"in, to, sars-cov, and"
7640,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.148148148,"is, that, sars-cov-2, in"
7641,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.148148148,"the, genome, of, sars-cov, and, bat, that, to"
7642,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.148148148,"that, of, to, is, shares, with, sars-cov-2, the"
7643,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.148148148,"bat, is, to, sars-cov-2"
7644,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.148148148,"that, the, of, are"
7645,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.148148148,"that, of, the, natural"
7646,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.148148148,"bats, are, the, of, can, and, be, to"
7647,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.148148148,"the, to, and, animal"
7648,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.148148148,"the, animal, be, of"
7649,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.148148148,"bats, and, are, sars-cov-2"
7650,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","with the first case being linked to  

a seafood market",0.148148148,"a, the, to, market"
7651,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","with the first case being linked to  

a seafood market",0.148148148,"with, a, the, market"
7652,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.148148148,"the, disease, in, and"
7653,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.148148148,"as, the, of, to, that, sars-cov-2, result, natural"
7654,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.148148148,"sars-cov-2, spillover, of, the"
7655,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.148148148,"that, the, was, of"
7656,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.148148148,"of, the, that, was"
7657,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.148148148,"in, humans, that, the, primary, case, and, sars-cov-2"
7658,"with the first case being linked to  

a seafood market","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.148148148,"the, to, a, market"
7659,"with the first case being linked to  

a seafood market","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.148148148,"with, the, a, market"
7660,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.148148148,"that, sars-cov-2, is, in"
7661,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.148148148,"evidence, that, in, sars-cov-2"
7662,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.148148148,"that, the, in, events, as, a, to, genetic"
7663,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.148148148,",, the, in, a, to, that, events, occur"
7664,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.148148148,"the, of, an, to, that, sars-cov-2, we, was"
7665,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.148148148,"and, that, a, of, the, is, most, likely"
7666,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.148148148,"was, in, the, horseshoe"
7667,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.148148148,"the, natural, of, in"
7668,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.148148148,"is, very, to, from"
7669,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.148148148,"the, be, host, of"
7670,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.148148148,"as, the, animal, of"
7671,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.148148148,"in, the, of, a"
7672,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.148148148,"the, from, to, with"
7673,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.148148148,"the, a, from, to"
7674,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.148148148,"has, the, ratg13, sars-cov-2"
7675,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.148148148,"bat, with, sars-cov-2, ratg13"
7676,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.148148148,"the, of, human, bat"
7677,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.148148148,"is, one, of, the"
7678,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.148148148,"the, of, between, and"
7679,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.148148148,"one, pangolin, and, intermediate, hosts, to, be, the"
7680,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.148148148,"the, of, is, and"
7681,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.148148148,"be, between, the, and"
7682,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.148148148,"the, from, a, who, at, market, and, to"
7683,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.148148148,"that, was, the, of"
7684,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.148148148,"a, virus, that, is"
7685,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.148148148,"the, animal, and, to"
7686,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.148148148,"to, is, and, the"
7687,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.148148148,"may, virus, that, is"
7688,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.148148148,"bats, are, the, reservoir"
7689,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.148148148,"was, seafood, market, in, wuhan, that, the, virus"
7690,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.148148148,"been, to, sars-cov-2, the"
7691,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.148148148,"of, the, sars-cov-2, group"
7692,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.148148148,"the, to, sars-cov-2, of"
7693,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.148148148,"all, covs, to, in"
7694,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.148148148,"that, the, sequence, of, sars-cov-2, bat, cov, sars-cov"
7695,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.148148148,"and, that, the, novel, 80%, 50%, of, bat"
7696,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.148148148,"of, the, that, are"
7697,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.148148148,"the, of, bat, human"
7698,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.148148148,"the, that, reservoir, of"
7699,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.148148148,"that, are, the, of"
7700,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.148148148,"most, the, in, which"
7701,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.148148148,"is, that, virus, a"
7702,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.148148148,"that, a, animal, is"
7703,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.148148148,"the, sars-cov-2, to, bat"
7704,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.148148148,"bats, the, of, sars"
7705,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.148148148,"in, that, bat, origin"
7706,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.148148148,"that, is, animal, a"
7707,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.148148148,"sars-cov-2, has, a, or"
7708,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.148148148,"the, genome, sequence, of, coronavirus, was, bat, and"
7709,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",COVID-19 is a zoonotic virus,0.148148148,"covid-19, is, a, zoonotic"
7710,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.148148148,"and, coronaviruses, are, to"
7711,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.148148148,"of, the, genome, sequence, and, was, bat, coronavirus"
7712,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.148148148,"novel, bat, that, the, of, and, 50%, 80%"
7713,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","no modifications were  

recorded for nonstructural proteins NSP7, NSP13  

and the structured and accessory proteins p6 and 8b.",0.148148148,"the, for, and, were"
7714,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.148148148,"a, from, sars-cov-2, is"
7715,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.148148148,"is, that, virus, may"
7716,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.148148148,"that, sars-cov-2, a, is"
7717,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.148148148,"this, a, that, is"
7718,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.148148148,"the, pangolin, in, on, that, for, a, of"
7719,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.148148148,"the, genome, of, that, sars-cov, and, to, bat"
7720,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.148148148,"the, of, sars-cov-2, other"
7721,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.148148148,"to, the, is, considered"
7722,"expended to make the simple point 

that COVID-19 had a natural origin.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.148148148,"to, the, that, a"
7723,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.148148148,"the, genome, was, to"
7724,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.148148148,"coronaviruses, are, to, and"
7725,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.148148148,"the, host, be, of"
7726,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.148148148,"of, the, that, a"
7727,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.148148148,"that, the, a, of"
7728,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.148148148,"in, the, horseshoe, was"
7729,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.148148148,"the, animal, of, be"
7730,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.148148148,"that, the, of, reservoir"
7731,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.148148148,"that, of, the, reservoir"
7732,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.148148148,"on, in, the, of, a, pangolin, that, for"
7733,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.148148148,"in, the, of, natural"
7734,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.148148148,"for, in, the, of"
7735,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.148148148,"as, the, of, and"
7736,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.148148148,"the, related, to, in"
7737,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.148148148,"the, of, that, to, in, it, is, this"
7738,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.148148148,"the, of, sars-cov-2, shares, with, that, is, to"
7739,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.148148148,"analysis, of, the, sars-, cov-2, that, sars-cov-2, is"
7740,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.148148148,"from, the, to, with"
7741,"According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.148148148,"the, sars-cov-2, group, of"
7742,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.148148148,"that, of, sars-, cov-2, is, sars-cov-2, analysis, the"
7743,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.148148148,"the, ratg13, has, sars-cov-2"
7744,"This suggests that the BANAL series may be able to directly infect  

humans.","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.148148148,"this, that, be, to"
7745,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.148148148,"to, the, that, sars-cov-2, as, result, of, natural"
7746,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.148148148,"that, pangolins, be, hosts, for, sars-cov-2, in, with"
7747,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.148148148,"a, from, the, to"
7748,"Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.148148148,"susceptible, live, animal, in"
7749,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.148148148,"sars-cov-2, similarity, to, with"
7750,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan",0.148148148,"animal, susceptible, live, in"
7751,Coronaviruses account for over 30% of the world’s viruses.,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.148148148,"coronaviruses, for, of, the"
7752,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.148148148,"of, and, the, or, in, bats, asia, southeast"
7753,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Bats are the second  

largest order of mammals, with over 1,230 species.",0.148148148,"bats, of, are, the"
7754,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",Coronaviruses account for over 30% of the world’s viruses.,0.148148148,"the, for, of, coronaviruses"
7755,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.148148148,"the, animal, of, as"
7756,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.148148148,"the, of, sars, bats"
7757,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.148148148,"the, of, as, and"
7758,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.148148148,"for, and, the, of"
7759,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.148148148,"the, reservoirs, for, and"
7760,"no modifications were  

recorded for nonstructural proteins NSP7, NSP13  

and the structured and accessory proteins p6 and 8b.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.148148148,"were, for, and, the"
7761,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.148148148,"the, in, related, to"
7762,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.148148148,"in, viruses, were, to"
7763,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.148148148,"important, and, the, of"
7764,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.148148148,"and, of, possible, similar, viruses, in, bat, southeast"
7765,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.148148148,"genetic, the, that, in, a, as, to, events"
7766,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,","This suggests that the BANAL series may be able to directly infect  

humans.",0.148148148,"be, that, to, this"
7767,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.148148148,"sars-cov-2, is, to, be"
7768,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.148148148,"the, primary, case, and, that, sars-cov-2, humans, in"
7769,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.148148148,"the, and, to, from, who, at, a, market"
7770,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.148148148,"at, the, in, a, to, that, events, animal"
7771,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.148148148,"that, a, virus, with, to, the, for, sars-cov-2"
7772,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","expended to make the simple point 

that COVID-19 had a natural origin.",0.148148148,"a, the, that, to"
7773,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.148148148,"is, any, previously, from"
7774,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.148148148,"that, was, the, of, sars-cov-2, we, to, an"
7775,The COVID-19 most likely developed from bat origin coronaviruses,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.148148148,"the, covid-19, most, bat"
7776,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",The COVID-19 most likely developed from bat origin coronaviruses,0.148148148,"the, most, bat, covid-19"
7777,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",The COVID-19 most likely developed from bat origin coronaviruses,0.148148148,"covid-19, most, the, bat"
7778,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.148148148,"viruses, to, were, in"
7779,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.148148148,"the, is, in, china"
7780,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.148148148,"the, which, most, in"
7781,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.148148148,"the, of, that, have, been, to, it, would"
7782,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.148148148,"of, the, that, natural"
7783,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.148148148,"the, is, one, of"
7784,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.148148148,"between, bats, and, may, during, the, or, in"
7785,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.148148148,"the, bats, is, and"
7786,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.148148148,"if, bats, are, to, virus, transmission, will, be"
7787,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.148148148,"be, virus, transmission, to, bats, are, if, will"
7788,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.148148148,"a, in, the, of"
7789,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.148148148,"and, the, or, from, in, bats, pangolins, southeast"
7790,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.148148148,"or, and, during, the, in, bats, may, between"
7791,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.148148148,"a, that, is, this"
7792,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.148148148,"the, pangolin, to, be, one, intermediate, hosts, and"
7793,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.148148148,"the, and, disease, in"
7794,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.148148148,"bats, is, and, the"
7795,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.148148148,"the, for, of, and"
7796,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.148148148,"was, the, of, sars-cov-2"
7797,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.148148148,"sars-cov-2, to, bat, the"
7798,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.148148148,"was, to, sars-cov-2, the"
7799,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.148148148,"most, that, a, likely, the, of, and, is"
7800,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.148148148,"ratg13, bat, with, sars-cov-2"
7801,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.148148148,"be, the, natural, of"
7802,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.148148148,"sars-cov-2, are, bats, and"
7803,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.148148148,"that, seafood, market, in, wuhan, the, virus, was"
7804,Bats are likely reservoir hosts for SARS-CoV-2,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.148148148,"are, hosts, for, sars-cov-2"
7805,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.148148148,"that, be, hosts, for, sars-cov-2, pangolins, in, with"
7806,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.148148148,"sars-cov-2, a, virus, that, with, to, the, for"
7807,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.148148148,"the, sars-cov-2, been, to"
7808,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.148148148,"sars-cov-2, in, a, of, and, that, the, with"
7809,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.148148148,"sars-cov-2, is, to, bat"
7810,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.148148148,"is, sars-cov-2, to, bat"
7811,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.148148148,"that, of, sars-cov-2, the"
7812,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.148148148,"this, that, are, the, origin, sars-cov-2, than, pa"
7813,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.148148148,"are, sars-cov-2, this, that, the, origin, than, pa"
7814,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.148148148,"with, similarity, to, sars-cov-2"
7815,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.148148148,"is, identical, to, sars-cov-2"
7816,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.148148148,"the, is, of, and"
7817,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.148148148,"spillover, and, the, transmission"
7818,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.148148148,"evidence, that, sars-cov-2, in"
7819,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.148148148,"the, of, in, for"
7820,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.148148148,"sars-cov-2, to, and, the"
7821,hese close genetic relations suggest that they all have their ecological origin in bat populations,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.148148148,"that, origin, in, bat"
7822,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.148148148,"is, very, from, to"
7823,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.148148148,"is, to, sars-cov-2, be"
7824,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.148148148,"the, be, between, and"
7825,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.148148148,"the, sars-cov-2, was, to"
7826,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.148148148,",, the, that, occur, in, a, to, events"
7827,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.148148148,"animal, at, a, in, the, events, that, to"
7828,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.148148148,"bats, be, the, natural, hosts, of, sars-, and"
7829,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.148148148,"of, southeast, and, similar, viruses, bat, possible, in"
7830,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.147540984,"in, the, of, it, is, to, sars-cov-2, with, a"
7831,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.147540984,"is, highly, unlikely, that, sars-cov-2, a, the, virus, from"
7832,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.147540984,"in, with, the, and, to, sars-cov-2, is, of, bat"
7833,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.147540984,"the, in, of, an, to, that, can, also, virus"
7834,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.147540984,"a, origin, of, the, from, that, sars-cov-2, into, humans"
7835,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.147540984,"the, that, sars-cov-2, a, of, into, humans, from, origin"
7836,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.147540984,"evidence, to, from, a, in, the, it, that, events"
7837,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.147540984,"who, market, in, that, the, virus, to, group, of"
7838,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.147540984,"the, genome, of, coronavirus, that, from, to, bat, and"
7839,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.147540984,"the, genome, of, to, that, coronavirus, from, and, bat"
7840,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.147540984,"to, a, of, the, and, it, has, been, that"
7841,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.147540984,"a, of, the, in, it, is, to, with, sars-cov-2"
7842,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.147540984,"evidence, the, that, in, a, it, to, events, from"
7843,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.147540984,"the, that, to, a, of, and, it, has, been"
7844,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.147540984,"the, of, evidence, that, sars-cov-2, a, has, been, in"
7845,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.147540984,"is, highly, unlikely, that, sars-cov-2, from, a, the, virus"
7846,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.147540984,"also, the, of, virus, can, in, that, to, an"
7847,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.147540984,"group, of, to, the, market, who, in, that, virus"
7848,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.147540984,"with, the, and, sars-cov-2, is, to, bat, in, of"
7849,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.147540984,"evidence, sars-cov-2, a, of, in, the, has, been, that"
7850,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.147058824,"sars-cov-2, viruses, are, to, and"
7851,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.147058824,"to, are, in, sars-cov-2, and"
7852,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.147058824,"the, species, to, of, and"
7853,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.147058824,"bats, are, the, reservoir, to"
7854,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.147058824,"genetic, and, have, sars-cov, bat"
7855,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.147058824,"sequences, similar, to, and, sars-cov-2."
7856,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.147058824,"sars-cov-2, and, to, bats, of"
7857,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.147058824,"that, sars-cov-2, a, and, is"
7858,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.147058824,"the, sars-cov-2, identical, with, to"
7859,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.147058824,"the, identity, of, sars-cov-2, is"
7860,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.147058824,"bat, virus, has, genome, of"
7861,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.147058824,"has, natural, origin, and, host"
7862,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.147058824,"are, a, of, covs,, the"
7863,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.147058824,"has, that, the, of, human"
7864,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.147058824,"bats, are, the, host, of"
7865,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.147058824,"the, and, a, that, in"
7866,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.147058824,"the, was, to, human, a"
7867,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.147058824,"in, the, a, was, and"
7868,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.147058824,"the, to, of, intermediate, hosts"
7869,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.147058824,"is, a, and, of, the"
7870,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.147058824,"the, to, coronavirus, and, a"
7871,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.147058824,"animal, and, the, of, is"
7872,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.147058824,"a, of, and, to, the"
7873,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.147058824,"be, the, and, an, of"
7874,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.147058824,"the, sources, of, are, and"
7875,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.147058824,"of, the, genomic, sequence, sars-cov-2"
7876,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.147058824,"is, with, a, origin, the"
7877,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.147058824,"with, a, sars-cov-2, from, zoonotic"
7878,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.147058824,"the, to, sars-cov, and, in"
7879,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.147058824,"analysis, that, the, of, bat"
7880,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.147058824,"to, that, of, sars-cov-2, the"
7881,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.147058824,"viral, that, natural, of, the"
7882,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.147058824,"to, the, respiratory, syndrome, coronavirus, in, and, that, animals, a"
7883,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.147058824,"the, of, to, and, bats"
7884,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.147058824,"the, sars-cov-2, of, and, to"
7885,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.147058824,"the, sars-cov-2, found, to, be"
7886,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.147058824,"a, the, that, in, and"
7887,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.147058824,"that, origin, in, which, and"
7888,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.147058824,"the, hypothesis, that, a, virus"
7889,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.147058824,"from, available, to, the, of"
7890,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.147058824,"the, of, sars-cov-2, to, natural"
7891,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.147058824,"the, ratg13, coronavirus, from, bat"
7892,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.147058824,"was, from, that, ratg13, and"
7893,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.147058824,"the, result, of, spillover, sars-cov-2"
7894,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.147058824,"from, animals, humans, for, the"
7895,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.147058824,"that, the, of, and, animals"
7896,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.147058824,"be, the, of, sars-cov-2, and"
7897,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.147058824,"the, with, a, is, origin"
7898,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.147058824,"is, at, the, of, a"
7899,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.147058824,"animal, to, were, in, the"
7900,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.147058824,"that, sars-cov-2, the, and, animal"
7901,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.147058824,"and, that, in, the, sars-cov-2"
7902,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.147058824,"with, a, from, sars-cov-2, zoonotic"
7903,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.147058824,"that, the, more, of, than"
7904,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.147058824,"to, is, a, virus, that, from, was, transmitted, the, as"
7905,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.147058824,"evidence, that, a, animal, is"
7906,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.147058824,"the, was, that, bat, as"
7907,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.147058824,"this, that, and, the, virus"
7908,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.147058824,"origin, and, which, that, in"
7909,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.147058824,"to, a, coronavirus, and, the"
7910,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.147058824,"that, the, and, sequence, to"
7911,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.147058824,"that, the, coronavirus, and, to"
7912,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.147058824,"a, that, the, covid-19, and"
7913,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.147058824,"a, of, in, bats, the"
7914,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.147058824,"of, the, in, a, with"
7915,"According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.147058824,"to, the, close, group, of"
7916,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.147058824,"from, that, identical, to, and"
7917,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.147058824,"a, to, the, virus, that, was, transmitted, is, from, as"
7918,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.147058824,"the, and, intermediate, that, virus, humans,, from, a, as, to"
7919,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.147058824,"from, intermediate, as, and, to, was, the, that, sars-cov-2, a"
7920,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.147058824,"the, have, been, from, to"
7921,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.147058824,"from, the, bat, coronavirus, ratg13"
7922,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.147058824,"the, with, bat, coronavirus, identity"
7923,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.147058824,"the, from, identity, with, sars-cov-2"
7924,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.147058824,"has, identity, with, bat, sars-cov-2"
7925,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.147058824,"sars-cov-2, the, with, bat, ratg13"
7926,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.147058824,"the, sars-cov-2, with, bat, ratg13"
7927,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.147058824,"that, the, virus, of, a"
7928,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.147058824,"available, to, the, of, virus"
7929,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.147058824,"a, that, the, of, and"
7930,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.147058824,"the, genetic, of, sars-cov-2, to"
7931,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.147058824,"suggested, the, of, sars-cov-2, and"
7932,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.147058824,"to, the, of, intermediate, hosts"
7933,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.147058824,"and, human, of, the, is"
7934,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.147058824,"of, the, to, bat, and"
7935,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.147058824,"to, pangolin, and, the, of"
7936,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.147058824,"a, virus, from, to, the"
7937,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.147058824,"the, in, to, from, bats"
7938,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.147058824,"is, a, of, at, the"
7939,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.147058824,"that, there, is, evidence, a"
7940,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.147058824,"a, of, that, the, virus"
7941,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.147058824,"virus, animals, to, humans, the"
7942,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.147058824,"that, jumped, the, and, humans"
7943,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.147058824,"that, the, to, and, in"
7944,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.147058824,"that, the, virus, to, and"
7945,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.147058824,"is, the, to, its, in"
7946,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.147058824,"the, to, and, that, sequence"
7947,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.147058824,"to, the, zoonotic, and, of"
7948,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.147058824,"t, the, that, bats, virus"
7949,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.147058824,"that, bats, the, of, and"
7950,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.147058824,"be, that, the, and, of"
7951,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.147058824,"and, identity, to, the, of"
7952,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.147058824,"bats, are, the, of, host"
7953,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.147058824,"that, sars-cov-2, is, to, be"
7954,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.147058824,"the, seafood, market, in, wuhan"
7955,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.147058824,"the, of, genome, bat, coronavirus"
7956,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.147058824,"group, of, to, the, close"
7957,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.147058824,"that, the, of, bat, it"
7958,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.147058824,"the, of, that, has, human"
7959,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.147058824,"that, the, has, of, bat"
7960,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.147058824,"the, coronaviruses, that, are, bat"
7961,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.147058824,"studies, that, may, to, sars-cov-2"
7962,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.147058824,"the, of, in, isolated, from"
7963,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.147058824,"the, of, as, a, from"
7964,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.147058824,"bat, have, genetic, sars-cov, and"
7965,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.147058824,"the, virus, in, which, probably"
7966,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.147058824,"is, zoonotic, to, a, virus"
7967,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.147058824,"animal, a, zoonotic, that, to"
7968,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.147058824,"that, is, a, virus, animal"
7969,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.147058824,"the, for, humans, from, animals"
7970,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.147058824,"the, virus, from, to, a"
7971,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.147058824,"the, to, virus, animals, humans"
7972,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.147058824,"in, closely, related, to, the"
7973,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.147058824,"the, from, bats, to, in"
7974,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.147058824,"of, the, in, isolated, from"
7975,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.147058824,"from, the, been, to, have"
7976,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.147058824,"to, human, in, animal, or"
7977,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.147058824,"sars-cov-2, and, is, a, that"
7978,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.147058824,"that, is, evidence, a, animal"
7979,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.147058824,"the, sars-cov-2, animal, that, and"
7980,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.147058824,"the, that, and, jumped, humans"
7981,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.147058824,"the, that, to, and, of"
7982,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.147058824,"the, to, coronavirus, and, that"
7983,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.147058824,"the, coronavirus, bat, identity, with"
7984,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.147058824,"with, the, to, of, genome"
7985,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.147058824,"available, to, the, of, from"
7986,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.147058824,"of, available, to, the, virus"
7987,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.147058824,"the, genome, bats, covid-19, virus"
7988,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.147058824,"the, three, viruses, are, to"
7989,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.147058824,"the, and, are, to, that"
7990,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.147058824,"sars-cov-2, the, of, sequence, genomic"
7991,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.147058824,"genome, from, was, wuhan, city,, that, the, related, to, of"
7992,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.147058824,"has, that, the, of, bat"
7993,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.147058824,"the, virus, sars, and, to"
7994,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.147058824,"that, sars-cov-2, through, laboratory, a"
7995,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.147058824,"human, animal, in, or, to"
7996,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.147058824,"is, of, animal, and, the"
7997,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.147058824,"the, is, of, and, wild"
7998,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.147058824,"is, sars-cov-2, a, virus, in"
7999,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.147058824,"and, are, the, sources, of"
8000,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.147058824,"the, of, are, to, sars-"
8001,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.147058824,"to, the, most, is, be"
8002,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.147058824,"is, to, likely, the, pangolin"
8003,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.147058824,"and, it, to, humans., the, of, that, been, a, infect"
8004,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.147058824,"of, the, sars-, cov-2, that"
8005,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.147058824,"that, the, similar, to, a"
8006,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.147058824,"the, of, sars-cov-2, are, with"
8007,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.147058824,"the, that, of, is, a"
8008,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.147058824,"analysis, that, the, of, a"
8009,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.147058824,"analysis, of, that, is, the"
8010,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.147058824,"seafood, market, in, wuhan, the"
8011,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.147058824,"the, sars-cov-2, was, to, bat"
8012,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.147058824,"closely, related, sars-cov-2, in, cambodia"
8013,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.147058824,"the, of, has, been, viruses"
8014,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.147058824,"of, the, as, from, a"
8015,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.147058824,"a, the, to, human, was"
8016,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.147058824,"the, was, a, coronavirus, to"
8017,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.147058824,"are, the, of, a, covs,"
8018,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.147058824,"the, of, has, a, and"
8019,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.147058824,"the, zoonotic, and, of, to"
8020,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.147058824,"a, in, similarity, with, sars-cov-2"
8021,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.147058824,"it, the, for, sars-cov-2, a"
8022,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.147058824,"that, the, is, sars-cov-2, or"
8023,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.147058824,"that, the, to, in, sars-cov-2"
8024,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.147058824,"is, that, sars-cov-2, into, the"
8025,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.147058824,"the, in, to, that, sars-cov-2"
8026,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.147058824,"virus, genome, bat, has, of"
8027,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.147058824,"a, sars-cov-2, similarity, with, in"
8028,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.147058824,"in, yunnan, that, of, sars-cov-2"
8029,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.147058824,"the, that, of, sars-, cov-2"
8030,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.147058824,"the, sars-cov-2, to, in, of"
8031,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.147058824,"sars-cov-2, to, the, in, of"
8032,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.147058824,"of, sars-cov-2, to, the, in"
8033,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.147058824,"in, were, to, humans, an"
8034,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.147058824,"this, can, be, assumed, that"
8035,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.147058824,"were, in, to, the, animal"
8036,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.147058824,"the, were, to, in, and"
8037,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.147058824,"that, been, a, recombination, of, with, to, and, the, sars-cov-2"
8038,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.147058824,"sars-cov-2, the, result, of, spillover"
8039,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.147058824,"virus, is, to, a, zoonotic"
8040,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.147058824,"sars-cov-2, a, virus, is, in"
8041,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.147058824,"the, of, closely, related, is, natural, in, a, virus, to"
8042,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.147058824,"the, of, and, viruses, bats"
8043,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.147058824,"that, the, coronaviruses, are, bat"
8044,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.147058824,"the, virus, in, to, and"
8045,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.147058824,"and, the, virus, to, sars"
8046,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.147058824,"the, of, and, to, bat"
8047,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.147058824,"in, viruses, are, different, and, bat, this, the, between, same"
8048,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.147058824,"are, viruses, to, the, three"
8049,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.147058824,"of, and, are, to, the"
8050,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.147058824,"are, to, the, that, and"
8051,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.147058824,"are, to, the, of, sars-"
8052,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.147058824,"similar, to, that, of, the"
8053,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.147058824,"the, is, of, natural, to, a, closely, related, virus, in"
8054,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.147058824,"the, of, with, that, to"
8055,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","This suggests that the BANAL series may be able to directly infect  

humans.",0.147058824,"this, to, that, the, be"
8056,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.147058824,"a, of, viruses, their, the"
8057,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.147058824,"the, is, closely, related, to"
8058,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.147058824,"to, a, virus, that, from, and, humans,, the, as, intermediate"
8059,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.147058824,"that, animal, to, a, zoonotic"
8060,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.147058824,"to, a, of, and, the"
8061,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.147058824,"of, the, viruses, a, their"
8062,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.147058824,"and, has, natural, host, origin"
8063,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.147058824,"that, sars-cov-2, through, a, laboratory"
8064,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.147058824,"is, that, of, the, reservoir"
8065,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.147058824,"into, the, that, is, sars-cov-2"
8066,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.147058824,"this, that, the, of, sars-cov-2"
8067,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.147058824,"the, analysis, that, of, bat"
8068,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.147058824,"the, genome, of, coronavirus, bat"
8069,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.147058824,"analysis, of, the, that, a"
8070,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.147058824,"the, of, bats, and, to"
8071,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.147058824,"in, an, were, to, humans"
8072,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.147058824,"the, to, in, is, be"
8073,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.147058824,"of, was, which, the, in"
8074,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.147058824,"analysis, of, the, that, is"
8075,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.147058824,"in, the, a, respiratory, syndrome, coronavirus, that, animals, to, and"
8076,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.147058824,"the, virus, which, probably, in"
8077,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.147058824,"the, of, is, that, reservoir"
8078,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.147058824,"a, the, in, and, was"
8079,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.147058824,"the, animals, that, and, of"
8080,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.147058824,"the, covid-19, and, that, a"
8081,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.147058824,"a, of, that, the, and"
8082,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.147058824,"wild, and, the, of, is"
8083,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.147058824,"a, of, the, that, and"
8084,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.147058824,"that, the, a, of, and"
8085,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.147058824,"this, that, the, and, of"
8086,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.147058824,"bat, has, identity, with, sars-cov-2"
8087,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.147058824,"a, hypothesis, that, the, virus"
8088,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.147058824,"such, studies, that, sars-cov-2, to"
8089,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.147058824,"to, sars-cov-2, a, that, from, and, was, the, as, intermediate"
8090,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.147058824,"the, that, to, infect, a, of, and, it, been, humans."
8091,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.147058824,"the, sars-cov-2, to, be, found"
8092,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.147058824,"the, to, sars-cov-2, was, bat"
8093,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.147058824,"bat, to, sars-cov-2, the, genome"
8094,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.147058824,"viral, of, the, that, natural"
8095,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.147058824,"the, is, of, and, human"
8096,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.147058824,"that, the, likely, origin, of"
8097,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.147058824,"and, sars-cov-2, are, to, viruses"
8098,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.147058824,"viruses, and, are, that, to"
8099,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.147058824,"and, that, from, ratg13, was"
8100,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.147058824,"to, identical, that, and, from"
8101,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.147058824,"that, sars-cov-2, are, to, ratg13"
8102,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.147058824,"with, sars-cov-2, bat, of, genome"
8103,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.147058824,"sars-cov-2, bat, ratg13, similarity, of"
8104,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.147058824,"with, the, sars-cov-2, to, of"
8105,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.147058824,"to, the, sars-cov-2, of, natural"
8106,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.147058824,"the, to, be, sars-cov-2, of"
8107,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.147058824,"of, genetic, to, sars-cov-2, the"
8108,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.147058824,"of, sars-cov-2, to, the, its"
8109,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.147058824,"of, the, in, which, was"
8110,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.147058824,"the, of, sars-cov-2, to, its"
8111,"This suggests that the BANAL series may be able to directly infect  

humans.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.147058824,"this, that, the, be, to"
8112,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.147058824,"this, the, origin, of, sars-"
8113,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.147058824,"t, that, the, virus, bats"
8114,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.147058824,"genome, bats, the, covid-19, virus"
8115,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.147058824,"the, genome, of, that, from, wuhan, city,, was, to, related"
8116,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.147058824,"bats, are, to, the, reservoir"
8117,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.147058824,"a, the, that, similar, to"
8118,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.147058824,"a, for, sars-cov-2, it, the"
8119,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.147058824,"to, sars-cov-2, a, recombination, of, the, and, been, that, with"
8120,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.147058824,"is, to, sars-cov-2, pangolin, cov"
8121,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.147058824,"the, of, viruses, has, been"
8122,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.147058824,"bats, the, viruses, of, and"
8123,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.147058824,"this, and, viruses, are, different, bat, between, in, the, same"
8124,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.147058824,"the, ratg13, bat, with, sars-cov-2"
8125,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.147058824,"the, pangolin, is, to, likely"
8126,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.147058824,"the, bat, or, pangolin, cov"
8127,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.147058824,"sars-cov-2, have, originated, in, or"
8128,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.147058824,"this, the, of, sars-, origin"
8129,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.147058824,"the, bat, cov, or, pangolin"
8130,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.147058824,"the, of, bat, cov, pangolin"
8131,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.147058824,"again, that, the, sars-cov-2, than"
8132,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.147058824,"more, than, of, the, that"
8133,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.147058824,"the, of, that, sars-cov-2, this"
8134,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.147058824,"that, origin, of, the, likely"
8135,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.147058824,"the, pangolin, to, of, and"
8136,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.147058824,"with, sars-cov-2, are, the, of"
8137,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.147058824,"sars-cov-2, that, are, to, ratg13"
8138,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.147058824,"the, bat, pangolin, of, cov"
8139,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.147058824,"bat-sl-cov-2, showed, to, that, sars-cov-2"
8140,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.147058824,"sars-cov-2, to, with, identical, the"
8141,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.147058824,"of, is, to, the, and"
8142,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.147058824,"the, of, pangolin-cov,, is, to"
8143,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.147058824,"the, of, sars-cov-2, is, identity"
8144,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.147058824,"the, sars-cov-2, that, in, and"
8145,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.147058824,"of, that, the, and, for"
8146,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.147058824,"that, the, and, bats, of"
8147,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.147058824,"and, sars-cov-2, are, to, in"
8148,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.147058824,"are, and, in, the, to"
8149,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.147058824,"that, the, and, this, virus"
8150,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.147058824,"be, of, an, and, the"
8151,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.147058824,"that, the, and, be, of"
8152,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.147058824,"can, be, assumed, that, this"
8153,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.147058824,"showed, that, sars-cov-2, to, bat-sl-cov-2"
8154,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.147058824,"cov, is, to, sars-cov-2, pangolin"
8155,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.147058824,"the, pangolin, as, intermediate, host"
8156,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.147058824,"the, was, as, that, bat"
8157,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.147058824,"the, bat, that, as, for"
8158,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.147058824,"studies, that, such, to, sars-cov-2"
8159,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.147058824,"the, and, sars-cov-2, bat, of"
8160,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.147058824,"the, be, sars-cov-2, and, of"
8161,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.147058824,"of, suggested, sars-cov-2, the, and"
8162,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.147058824,"sars-cov-2, and, bat, the, of"
8163,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.147058824,"virus, that, is, animal, a"
8164,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.147058824,"the, of, sars-cov-2, that, to"
8165,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.147058824,"that, in, yunnan, of, sars-cov-2"
8166,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.147058824,"the, of, similar, to, that"
8167,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.147058824,"that, the, sars-cov-2, similar, to"
8168,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.147058824,"the, is, to, its, in"
8169,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.147058824,"is, the, closely, related, to"
8170,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.147058824,"the, of, is, pangolin-cov,, to"
8171,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.147058824,"the, and, of, identity, to"
8172,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.147058824,"of, bat, similarity, sars-cov-2, ratg13"
8173,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.147058824,"that, the, sars-cov-2, is, a"
8174,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.147058824,"is, that, the, sars-cov-2, or"
8175,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.146853147,"in, a, of, to, the, collected, from, tested, positive, for, different, coronavirus, two, and, sars, at, were, closely, related, than, virus"
8176,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.146853147,"the, also, for, to, a, sars-related, virus, that, similar, with, sars,, used, ace2, as, cellular, and, researchers, by, sars, in, of"
8177,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.146853147,"in, than, the, sars, of, from, tested, positive, for, two, at, virus, collected, to, different, were, a, coronavirus, closely, related, and"
8178,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.146853147,"by, the, of, a, sars-related, in, to, that, sars, with, as, and, sars,, researchers, virus, similar, also, used, ace2, for, cellular"
8179,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.146666667,"the, of, and, virus, into, humans,, from, palm, human, with, to"
8180,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.146666667,"from, early, in, humans, two, lineage, the, of, that, a, sars-cov-2"
8181,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.146666667,"a, of, the, from, lineage, that, early, sars-cov-2, two, in, humans"
8182,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.146666667,"to, sars-cov-2, from, a, of, sequences, in, bats, the, that, with"
8183,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.146666667,"that, of, from, bats, to, a, in, with, sars-cov-2, sequences, the"
8184,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.146666667,"to, with, the, of, and, into, humans,, from, virus, palm, human"
8185,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.146666667,"of, evidence, that, the, a, from, species, as, intermediate, or, for"
8186,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.146666667,"for, the, of, intermediate, species, that, from, a, evidence, or, as"
8187,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.146341463,"sars-cov, and, sars-cov-2, to, bat, in"
8188,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.146341463,"in, a, related, are, closely, to"
8189,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.146341463,"a, viruses, in, and, to, which"
8190,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.146341463,"the, are, or, horseshoe, bats, in"
8191,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.146341463,"sars-cov-2, is, a, virus, that, and"
8192,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.146341463,"and, bat, coronaviruses, to, the, of"
8193,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.146341463,"a, that, the, was, to, sars-cov-2"
8194,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.146341463,"of, a, that, the, to, bat"
8195,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.146341463,"that, the, sars-cov-2, bat, cov, is"
8196,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.146341463,"is, the, bat, to, sequence, of"
8197,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.146341463,"of, and, viruses, are, a, the"
8198,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.146341463,"the, genome,, is, to, of, and"
8199,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.146341463,"the, is, of, sars-cov-2, to, in"
8200,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.146341463,"the, known, and, is, of, to"
8201,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.146341463,"genome, sequence, with, bat, and, sars-cov-2"
8202,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.146341463,"that, sars-cov-2, the, and, humans, animal"
8203,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.146341463,"the, origin, of, sars-cov-2, between, and"
8204,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.146341463,"between, and, that, the, of, sars-cov-2"
8205,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.146341463,"a, of, in, bats, the, as"
8206,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.146341463,"are, zoonotic, viruses, the, order, and"
8207,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.146341463,"the, in, to, that, was, virus"
8208,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.146341463,"a, that, the, virus, to, and"
8209,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.146341463,"is, the, to, closest, sequence, in"
8210,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.146341463,"the, of, to, sars-cov-2, from, bats"
8211,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.146341463,"that, market, in, wuhan, the, it"
8212,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.146341463,"it, is, that, the, likely, to"
8213,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.146341463,"of, has, that, by, the, and"
8214,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.146341463,"that, bats, are, the, of, and"
8215,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.146341463,"the, sars-cov-2, isolated, from, origin, is"
8216,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.146341463,"the, sars-cov-2, of, is, that, bat"
8217,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.146341463,"in, the, analysis, of, that, sars-cov-2"
8218,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.146341463,"the, that, sars-cov-2, to, bat, and"
8219,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.146341463,"the, of, to, animal, can, be"
8220,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.146341463,"and, of, sars-cov-2, to, animal, be"
8221,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.146341463,"of, sars-cov-2, has, yet, been, the"
8222,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.146341463,"the, other, by, that, not, a"
8223,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.146341463,"of, sars-cov-2, into, humans, from, to"
8224,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.146341463,"the, hypothesis, that, to, a, of"
8225,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.146341463,"the, of, that, sars-cov-2, to, a"
8226,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.146341463,"the, of, evidence, that, sars-cov-2, a"
8227,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.146341463,"nucleotide, of, and, from, bat, ratg13"
8228,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.146341463,"studies, have, that, the, of, and"
8229,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.146341463,"the, of, hypothesis, that, sars-cov-2, into"
8230,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.146341463,"to, the, of, coronaviruses,, a, bat"
8231,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.146341463,"that, the, of, viruses, to, sars-cov-2"
8232,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.146341463,"the, to, that, are, sars-cov-2, bat"
8233,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.146341463,"that, sars-cov-2, from, a, bat, to"
8234,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.146341463,"the, that, sars-cov-2, at, of, to"
8235,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.146341463,"to, sars-cov-2, be, that, and, the"
8236,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.146341463,"are, known, and, the, that, to"
8237,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.146341463,"to, that, the, of, and, be"
8238,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.146341463,"the, of, that, sars-cov-2, are, to"
8239,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.146341463,"hypothesis, that, sars-cov-2, the, of, into"
8240,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.146341463,"are, closely, related, to, in, a"
8241,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.146341463,"the, to, a, closely, related, in"
8242,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.146341463,"are, a, in, the, that, to"
8243,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.146341463,"at, a, and, this, in, the"
8244,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.146341463,"this, the, of, origin, and, is"
8245,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.146341463,"the, of, from, by, a, virus"
8246,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.146341463,"the, was, in, and, that, within"
8247,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.146341463,"to, sars-cov-2, of, into, humans, from"
8248,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.146341463,"sars-cov-2, to, in, zoonotic, and, of"
8249,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.146341463,"and, that, the, covid-19, to, of"
8250,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.146341463,"the, of, more, than, to, and"
8251,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.146341463,"in, and, research, are, if, to, make, viruses, used, other, there, laboratory"
8252,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.146341463,"there, are, other, make, if, to, and, viruses, used, in, laboratory, research"
8253,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.146341463,"to, is, a, that, originated, from"
8254,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.146341463,"covid-19, is, spillover, to, a, in"
8255,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.146341463,"covid-19, is, evidence, a, spillover, to"
8256,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.146341463,"animal, a, in, spillover, that, to"
8257,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.146341463,"evidence, that, is, a, in, animal"
8258,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.146341463,"that, to, and, a, on, the"
8259,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.146341463,"to, a, that, and, was, the"
8260,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.146341463,"the, that, to, a, bat, genome"
8261,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.146341463,"density, and, to, in, the, of"
8262,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.146341463,"the, and, genome,, is, to, of"
8263,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.146341463,"sars-cov-2, and, is, a, virus, that"
8264,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.146341463,"the, that, to, be, sars-cov-2, and"
8265,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.146341463,"that, is, originated, from, a, to"
8266,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.146341463,"he, of, the, spike, protein, from"
8267,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.146341463,"has, that, and, the, of, by"
8268,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.146341463,"the, of, sars-cov-2, to, a, virus"
8269,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.146341463,"is, to, the, between, and, be"
8270,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.146341463,"to, in, bats, and, china, from"
8271,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.146341463,"in, animals, and, to, humans, through"
8272,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.146341463,"that, the, covid-19, to, through, of"
8273,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.146341463,"and, in, to, the, origin, is"
8274,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.146341463,"is, to, origin, the, that, and"
8275,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.146341463,"that, bats, be, the, sars-cov-2, genomic"
8276,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.146341463,"the, that, market, in, wuhan, it"
8277,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.146341463,"the, samples, from, market, that, at"
8278,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.146341463,"the, sars-cov-2, is, and, to, sars-cov"
8279,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.146341463,"the, animal, of, can, be, to"
8280,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.146341463,"the, of, sars-cov-2, between, sarbecovirus, and"
8281,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.146341463,"he, from, the, spike, protein, of"
8282,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.146341463,"of, bat, is, likely, that, bats"
8283,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.146341463,"a, it, the, for, to, is"
8284,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.146341463,"from, a, is, to, the, it"
8285,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.146341463,"in, the, of, closely, related, to"
8286,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.146341463,"in, an, from, to, and, the"
8287,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.146341463,"the, that, humans, and, animal, sars-cov-2"
8288,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.146341463,"animal, of, sars-cov-2, and, be, to"
8289,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.146341463,"another, sars-cov-2, be, between, and, an"
8290,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.146341463,"to, the, virus, bats, be, of"
8291,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.146341463,"are, the, and, zoonotic, viruses, order"
8292,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.146341463,"the, of, is, to, sars-cov-2, that"
8293,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.146341463,"of, the, covid-19, to, and, that"
8294,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.146341463,"not, a, that, the, by, other"
8295,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.146341463,"that, the, between, and, bat, is"
8296,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.146341463,"the, from, that, to, and, animals"
8297,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.146341463,"that, sequences, are, to, the, of"
8298,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.146341463,"genome, with, that, and, sars-cov-2, a"
8299,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.146341463,"the, of, animal, and, sars-cov-2, humans"
8300,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.146341463,"of, and, are, the, hosts, sars-cov-2"
8301,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.146341463,"to, the, hypothesis, that, a, of"
8302,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.146341463,"in, the, of, to, at, that"
8303,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.146341463,"are, closely, related, coronaviruses, to, and"
8304,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.146341463,"the, of, to, suggesting, that, directly"
8305,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.146341463,"hypothesis, the, analysis, of, that, sars-cov-2"
8306,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.146341463,"the, within, was, that, in, and"
8307,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.146341463,"of, that, the, and, for, was"
8308,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.146341463,"the, origin, of, between, and, sars-cov-2"
8309,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.146341463,"the, between, sars-cov-2, and, of, sarbecovirus"
8310,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.146341463,"the, analysis, that, sars-cov-2, in, of"
8311,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.146341463,"the, of, in, closely, related, to"
8312,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.146341463,"analysis, of, the, hypothesis, that, sars-cov-2"
8313,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.146341463,"that, bats, are, hosts, for, to"
8314,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.146341463,"zoonotic, of, sars-cov-2, in, and, to"
8315,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.146341463,"the, of, zoonotic, sars-cov-2, to, in"
8316,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.146341463,"because, similarity, sars-cov-2, cov, the, in"
8317,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.146341463,"a, to, bat, coronaviruses,, the, of"
8318,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.146341463,"viruses, to, that, the, of, sars-cov-2"
8319,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.146341463,"nucleotide, sequences, of, sars-cov-2, and, from"
8320,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.146341463,"sars-cov-2, and, identity, coronaviruses, the, of"
8321,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.146341463,"the, from, an, in, to, and"
8322,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.146341463,"the, of, to, and, in, bats"
8323,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.146341463,"amino, acid, ratg13, the, s, protein"
8324,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.146341463,"the, sars-cov-2, has, with, at, of"
8325,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.146341463,"he, with, sequence, of, s, protein"
8326,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.146341463,"ratg13, s, protein, the, amino, acid"
8327,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.146341463,"was, that, the, sars-cov-2, to, a"
8328,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.146341463,"the, was, a, that, and, to"
8329,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.146341463,"the, to, that, sars-cov-2, in, and"
8330,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.146341463,"the, samples, from, at, market, that"
8331,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.146341463,"in, sars-cov-2, found, to, with, coronavirus"
8332,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.146341463,"the, of, that, sars-cov-2, in, for"
8333,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.146341463,"the, sars-cov-2, is, to, in, of"
8334,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.146341463,"in, a, related, the, closely, to"
8335,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.146341463,"is, covid-19, in, a, spillover, to"
8336,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.146341463,"a, of, to, sars-cov-2, the, virus"
8337,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.146341463,"sars-cov-2, to, the, in, zoonotic, of"
8338,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.146341463,"a, of, in, natural, to, the"
8339,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.146341463,"the, are, in, or, horseshoe, bats"
8340,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.146341463,"of, most, to, the, bat, and"
8341,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.146341463,"are, to, bat, that, the, sars-cov-2"
8342,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.146341463,"that, the, to, and, in, sars-cov-2"
8343,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.146341463,"that, sars-cov-2, are, to, and, the"
8344,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.146341463,"the, virus, in, and, to, china"
8345,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.146341463,"the, of, in, to, density, and"
8346,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.146341463,"are, the, of, a, and, viruses"
8347,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.146341463,"in, the, of, a, between, and"
8348,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.146341463,"a, by, in, that, the, virus, is, closely, related, to, of, found"
8349,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.146341463,"the, of, most, closely, bat, after"
8350,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.146341463,"the, of, a, was, and, market"
8351,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.146341463,"the, that, have, in, of, cases, to, retrospective, case, with, a, but, not, all, early, had, an, association"
8352,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.146341463,"association, that, had, a, the, an, retrospective, case, with, early, cases, of, in, not, have, but, all, to"
8353,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.146341463,"the, known, and, is, to, of"
8354,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.146341463,"is, evidence, covid-19, a, spillover, to"
8355,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.146341463,"a, of, natural, and, to, the"
8356,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.146341463,"the, that, are, known, to, and"
8357,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.146341463,"in, a, that, the, are, to"
8358,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.146341463,"this, a, and, at, the, in"
8359,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.146341463,"that, in, a, spillover, animal, to"
8360,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.146341463,"a, study, by, al., from, was, at, seafood, in, that, the, of"
8361,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.146341463,"and, from, bats, to, in, china"
8362,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.146341463,"from, in, china, coronaviruses, including, sars-cov-2"
8363,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.146341463,"and, to, in, a, which, viruses"
8364,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.146341463,"the, of, natural, to, a, in"
8365,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.146341463,"the, and, of, a, natural, to"
8366,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.146341463,"the, natural, and, to, number, of"
8367,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.146341463,"the, in, that, sars-cov-2, a, with"
8368,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.146341463,"that, is, likely, bats, of, bat"
8369,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.146341463,"is, the, bat, to, its, of"
8370,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.146341463,"a, from, to, the, it, is"
8371,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.146341463,"the, shows, that, evolutionary, of, and"
8372,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.146341463,"the, to, that, in, virus, was"
8373,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.146341463,"the, that, sars-cov-2, of, virus, to"
8374,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.146341463,"after, the, of, most, closely, bat"
8375,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.146341463,"more, than, of, the, to, and"
8376,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.146341463,"in, of, bats, to, and, the"
8377,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.146341463,"the, to, sequence, in, of, than"
8378,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.146341463,"that, the, from, animals, to, and"
8379,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.146341463,"analysis, that, the, covid-19, and, to"
8380,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.146341463,"phylogenetic, analysis, that, the, and, to"
8381,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.146341463,"the, of, covid-19, through, to, that"
8382,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.146341463,"through, in, and, to, humans, animals"
8383,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.146341463,"the, was, and, that, for, of"
8384,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.146341463,"the, most, to, of, bat, and"
8385,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.146341463,"this, that, the, of, trade, animals"
8386,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.146341463,"in, the, of, as, a, bats"
8387,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.146341463,"the, bats, and, to, humans, from"
8388,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.146341463,"of, and, a, between, in, the"
8389,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.146341463,"the, was, a, market, and, of"
8390,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.146341463,"the, isolated, from, sars-cov-2, is, origin"
8391,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.146341463,"he, s, protein, sequence, with, of"
8392,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.146341463,"the, this, that, trade, of, animals"
8393,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.146341463,"with, and, sars-cov-2, bat, genome, sequence"
8394,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.146341463,"a, sars-cov-2, genome, with, that, and"
8395,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.146341463,"the, sars-cov-2, of, virus, is, that"
8396,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.146341463,"a, to, bat, that, sars-cov-2, from"
8397,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.146341463,"the, sars-cov-2, has, been, of, yet"
8398,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.146341463,"the, is, to, and, origin, in"
8399,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.146341463,"to, sars-cov-2, similarity, the, be, of"
8400,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.146341463,"nucleotide, and, from, bat, ratg13, of"
8401,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.146341463,"nucleotide, sequences, of, from, and, sars-cov-2"
8402,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.146341463,"to, emergence, the, plausible, scenario, of"
8403,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.146341463,"consistent, to, that, the, of, and, may, are, more, origin, sars-cov-2, than"
8404,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.146341463,"this, is, and, origin, of, the"
8405,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.146341463,"of, to, the, scenario, emergence, plausible"
8406,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.146341463,"this, be, that, the, and, of"
8407,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.146341463,"genomic, that, sars-cov-2, bats, be, the"
8408,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.146341463,"that, the, sars-cov-2, to, a, bat"
8409,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.146341463,"the, sars-cov-2, cluster, and, bat, pangolin"
8410,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.146341463,"the, of, closely, related, is, by, in, found, a, virus, to, that"
8411,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.146341463,"at, the, seafood, that, was, of, in, study, from, a, by, al."
8412,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.146341463,"the, that, to, it, is, likely"
8413,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.146341463,"bats, to, that, are, hosts, for"
8414,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.146341463,"the, that, sars-cov-2, to, a, bat"
8415,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.146341463,"that, the, of, to, a, bat"
8416,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.146341463,"a, of, bat, in, china, sars-cov-2"
8417,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.146341463,"the, of, sars-cov-2, are, hosts, and"
8418,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.146341463,"a, that, with, the, sars-cov-2, in"
8419,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.146341463,"sars-cov-2, because, similarity, the, cov, in"
8420,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.146341463,"that, the, sars-cov-2, is, bat, cov"
8421,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.146341463,"that, sars-cov-2, has, the, origin, we"
8422,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.146341463,"the, sars-cov-2, cluster, bat, and, pangolin"
8423,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.146341463,"that, are, more, than, the, sars-cov-2, to, may, consistent, of, origin, and"
8424,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.146341463,"on, the, a, that, and, to"
8425,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.146341463,"the, sequences, are, to, that, of"
8426,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.146341463,"the, genome, to, bat, that, a"
8427,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.146341463,"the, sars-cov-2, and, to, is, sars-cov"
8428,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.146341463,"the, phylogenetic, analysis, that, to, and"
8429,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.146341463,"the, of, that, between, and, sars-cov-2"
8430,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.146341463,"the, between, sars-cov-2, and, of, that"
8431,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.146341463,"that, bats, and, are, the, of"
8432,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.146341463,"studies, and, that, have, the, of"
8433,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.146341463,"at, to, that, the, of, sars-cov-2"
8434,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.146341463,"has, at, the, of, with, sars-cov-2"
8435,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.146341463,"and, the, of, shows, that, evolutionary"
8436,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.146341463,"that, sars-cov-2, to, and, the, of"
8437,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.146341463,"this, that, the, of, and, be"
8438,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.146341463,"to, the, of, sars-cov-2, from, bats"
8439,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.146341463,"to, that, the, of, sars-cov-2, from"
8440,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.146341463,"of, directly, to, the, suggesting, that"
8441,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.146341463,"from, of, bats, to, sars-cov-2, the"
8442,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.146341463,"in, the, that, to, of, at"
8443,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.146341463,"in, to, that, of, sars-cov-2, the"
8444,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.146341463,"the, similarity, of, sars-cov-2, to, be"
8445,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.146341463,"we, that, sars-cov-2, has, the, origin"
8446,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.146341463,"of, a, virus, the, by, from"
8447,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.146341463,"study, the, of, an, intermediate, host"
8448,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.146341463,"between, and, sars-cov-2, an, another, be"
8449,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.146341463,"evidence, the, that, sars-cov-2, a, of"
8450,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.146341463,"that, is, evidence, in, a, animal"
8451,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.146341463,"with, the, and, is, to, of"
8452,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.146341463,"number, of, natural, and, to, the"
8453,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.146341463,"coronaviruses, sars-cov-2, in, including, china, from"
8454,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.146341463,"a, bat, of, sars-cov-2, in, china"
8455,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.146341463,"coronavirus, with, to, sars-cov-2, found, in"
8456,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.146341463,"has, the, closest, relationship, with, at"
8457,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.146341463,"in, the, of, to, sars-cov-2, that"
8458,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.146341463,"the, sequence, of, is, to, bat"
8459,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.146341463,"is, the, closest, to, in, sequence"
8460,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.146341463,"the, of, to, bat, is, its"
8461,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.146341463,"the, sequence, of, than, to, in"
8462,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.146341463,"study, the, host, of, an, intermediate"
8463,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.146341463,"the, and, of, bat, coronaviruses, to"
8464,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.146341463,"the, of, coronaviruses, and, identity, sars-cov-2"
8465,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.145833333,"more, than, were, bats, of, infected, and"
8466,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.145833333,"and, have, to, genetic, in, bat, coronaviruses"
8467,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.145833333,"in, of, more, than, to, sars-cov-2, and"
8468,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.145833333,"of, more, than, and, bats, were, infected"
8469,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.145833333,"with, the, sars-cov, and, to, bat, of"
8470,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.145833333,"it, is, the, sars-cov-2, as, to, a"
8471,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.145833333,"other, are, to, and, a, the, of"
8472,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.145833333,"to, sars-cov-2, virus, that, and, was, the"
8473,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.145833333,"sars-cov-2, to, the, same, bat, cov, ratg13"
8474,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.145833333,"of, phylogenetic, analysis, that, which, many, and"
8475,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.145833333,"the, genome, of, to, with, and, bat"
8476,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.145833333,"to, humans, and, can, the, of, sars-cov-2"
8477,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.145833333,"that, the, of, were, in, to, market"
8478,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.145833333,"in, it, is, that, the, covid-19, infected"
8479,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.145833333,"the, an, animal, and, a, of, sars-cov-2"
8480,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.145833333,"the, from, civets, for, that, palm, hosts"
8481,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.145833333,"with, and, to, sars-cov-2, the, whole, genome"
8482,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.145833333,"that, bats, are, the, natural, of, for"
8483,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.145833333,"sars-cov-2, is, found, humans, through, to, the"
8484,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.145833333,"the, of, hypothesis, that, sars-cov-2, into, humans"
8485,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.145833333,"such, have, and, the, sars-cov-2, natural, has"
8486,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.145833333,"this, of, viruses, are, bat, a, the"
8487,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.145833333,"the, of, and, huanan, market, that, sars-cov-2"
8488,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.145833333,"that, of, to, and, are, the, sars-cov-2"
8489,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.145833333,"the, hypothesis, that, sars-cov-2, of, into, humans"
8490,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.145833333,"the, huanan, market, that, sars-cov-2, and, of"
8491,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.145833333,"of, the, sars-cov-2, with, that, presence, and"
8492,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.145833333,"the, market, that, presence, of, in, sars-cov-2"
8493,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.145833333,"sars-cov-2, a, of, an, animal, and, the"
8494,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.145833333,"of, the, early, cases, have, in, that"
8495,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.145833333,"evidence, that, covid-19, is, a, from, animal"
8496,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.145833333,"has, a, and, with, the, virus, bat"
8497,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.145833333,"the, is, that, huanan, seafood, and, also"
8498,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.145833333,"the, of, that, were, to, market, in"
8499,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.145833333,"to, that, has, the, virus, genome,, of"
8500,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.145833333,"virus, the, was, to, and, that, sars-cov-2"
8501,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.145833333,"to, that, sars-cov-2, the, virus, bats, be"
8502,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.145833333,"with, the, and, to, bat, of, genome"
8503,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.145833333,"a, of, the, genome, with, that, and"
8504,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.145833333,"and, bat, identity, pangolin, to, the, of"
8505,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.145833333,"the, of, can, to, humans, and, sars-cov-2"
8506,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.145833333,"an, of, to, sars-cov-2, and, the, humans"
8507,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.145833333,"and, the, of, which, that, by, evolutionary"
8508,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.145833333,"the, of, an, to, that, sars-cov-2, was"
8509,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.145833333,"of, analysis, that, the, to, which, and"
8510,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.145833333,"in, from, bats, to, and, the, humans"
8511,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.145833333,"the, genetic, in, from, market, that, at"
8512,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.145833333,"and, are, the, of, which, is, transmitted"
8513,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.145833333,"the, was, huanan, seafood, and, of, december"
8514,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.145833333,"to, that, the, of, bats, and, may"
8515,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.145833333,"from, hosts, that, for, the, palm, civets"
8516,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.145833333,"that, the, of, a, bat, coronavirus, after"
8517,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.145833333,"the, of, virus, to, genetic, is, bat"
8518,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.145833333,"a, the, in, spike, protein, from, pangolin"
8519,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.145833333,"an, species, of, to, sars-cov-2, and, humans"
8520,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.145833333,"the, is, coronavirus, sequence, that, beta, coronaviruses"
8521,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.145833333,"coronavirus, the, genome, that, was, to, of"
8522,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.145833333,"are, is, of, the, which, and, transmitted"
8523,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.145833333,"the, virus, a, has, with, bat, and"
8524,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.145833333,"the, sequence, of, identity, sars-cov, and, in"
8525,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.145833333,"the, sars-cov-2, has, with, of, virus, and"
8526,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.145833333,"a, of, likely, based, on, comparative, analysis"
8527,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.145833333,"the, presence, of, with, and, that, sars-cov-2"
8528,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.145833333,"the, a, genome, of, with, that, and"
8529,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.145833333,"that, a, of, with, and, the, sars-cov-2"
8530,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.145833333,"the, of, to, it, is, infect, and"
8531,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.145833333,"the, to, it, that, has, been, of"
8532,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.145833333,"the, genome, of, coronavirus, that, was, to"
8533,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.145833333,"hypothesis, in, the, of, that, was, pangolin"
8534,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.145833333,"the, pangolin, hypothesis, was, in, that, of"
8535,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.145833333,"analysis, that, the, virus, in, to, of"
8536,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.145833333,"analysis, that, sars-cov-2, the, of, virus, to"
8537,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.145833333,"as, to, the, of, a, high, human"
8538,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.145833333,"the, of, human, to, a, high, as"
8539,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.145833333,"no, been, by, and, to, the, sars-cov-2"
8540,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.145833333,"and, sars-cov-2, in, to, of, more, than"
8541,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.145833333,"the, of, coronaviruses, from, with, and, sars-cov-2"
8542,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.145833333,"two, of, the, sars-cov-2, in, from, and"
8543,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.145833333,"in, an, from, to, sars-cov-2, and, the"
8544,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.145833333,"the, of, and, sars-cov-2, an, to, humans"
8545,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.145833333,"the, in, bats, and, to, humans, from"
8546,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.145833333,"humans, and, of, sars-cov-2, to, an, species"
8547,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.145833333,"in, to, the, sars-cov-2, from, and, an"
8548,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.145833333,"for, between, and, that, in, the, sars-cov-2"
8549,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.145833333,"the, is, to, infect, of, and, it"
8550,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.145833333,"genetic, that, the, in, from, at, market"
8551,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.145833333,"the, was, taken, from, at, market, of"
8552,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.145833333,"the, presence, of, market, that, sars-cov-2, in"
8553,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.145833333,"covid-19, a, in, the, sars-cov-2, pandemic, or"
8554,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.145833333,"a, viruses, are, bat, the, of, this"
8555,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.145833333,"the, whole, genome, sars-cov-2, with, and, to"
8556,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.145833333,"the, and, 103, are, similar, to, sars-"
8557,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.145833333,"it, are, the, sars-cov-2, similar, to, a"
8558,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.145833333,"sars-, 103, and, are, similar, to, the"
8559,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.145833333,"the, genetic, of, virus, is, to, bat"
8560,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.145833333,"the, infected, that, in, it, is, covid-19"
8561,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.145833333,"huanan, seafood, the, was, december, and, of"
8562,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.145833333,"from, the, was, also, for, first, to, a, live, virus, that, similar, as, and, by, sars, in, of, coronavirus, known, at"
8563,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.145833333,"in, the, first, known, sars, live, of, from, that, for, as, at, also, virus, was, similar, to, by, a, coronavirus, and"
8564,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.145833333,"that, the, huanan, seafood, and, also, is"
8565,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.145833333,"the, sars-cov-2, to, humans, through, is, found"
8566,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.145833333,"the, similarity, of, sars-cov-2, coronaviruses, to, natural"
8567,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.145833333,"the, of, and, that, which, by, evolutionary"
8568,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.145833333,"the, of, that, sars-cov-2, an, was, to"
8569,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.145833333,"virus, pangolins, in, similar, sars-cov-2, the, of"
8570,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.145833333,"the, of, coronaviruses, from, and, with, sars-cov-2"
8571,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.145833333,"however,, the, rbd, of, that, sars-cov-2, not"
8572,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.145833333,"a, of, the, after, coronavirus, bat, that"
8573,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.145833333,"on, in, wuhan, the, origin, of, based"
8574,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.145833333,"sequence, identity, and, sars-cov, the, of, in"
8575,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.145833333,"that, is, evidence, covid-19, from, a, animal"
8576,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.145833333,"in, the, analysis, of, that, to, virus"
8577,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.145833333,"early, cases, in, the, of, that, have"
8578,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.145833333,"of, the, chinese, been, by, that, have"
8579,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.145833333,"of, the, that, bats, are, natural, for"
8580,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.145833333,"evidence, that, bats, and, pangolins, are, for"
8581,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.145833333,"the, that, to, of, it, has, been"
8582,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.145833333,"the, of, this, that, has, been, in"
8583,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.145833333,"the, of, from, two, and, in, sars-cov-2"
8584,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.145833333,"the, in, pangolins, of, similar, sars-cov-2, virus"
8585,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.145833333,"comparative, analysis, based, on, of, a, likely"
8586,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.145833333,"of, the, have, been, that, by, chinese"
8587,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.145833333,"the, genetic, of, sars-cov-2, with, consistent, natural"
8588,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.145833333,"sars-cov-2, has, have, natural, and, such, the"
8589,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.145833333,"to, no, been, by, and, the, sars-cov-2"
8590,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.145833333,"the, spike, protein, in, from, a, pangolin"
8591,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.145833333,"coronaviruses, similarity, to, sars-cov-2, the, of, natural"
8592,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.145833333,"the, consistent, with, of, natural, genetic, sars-cov-2"
8593,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.145833333,"the, sequence, that, coronavirus, is, beta, coronaviruses"
8594,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.145833333,"to, this, that, the, be, origin, of"
8595,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.145833333,"sars-cov-2, and, bat, pangolin, to, the, that"
8596,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.145833333,"evidence, that, bats, are, and, pangolins, for"
8597,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.145833333,"as, a, the, it, is, to, sars-cov-2"
8598,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.145833333,"it, a, are, similar, to, sars-cov-2, the"
8599,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.145833333,"and, phylogenetic, analysis, that, of, many, which"
8600,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.145833333,"the, analysis, of, and, that, which, to"
8601,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.145833333,"in, et, al., (2020), of, genome, sequences"
8602,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.145833333,"et, al., (2020), of, genome, sequences, in"
8603,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.145833333,"a, of, the, sars-cov-2, with, that, and"
8604,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.145833333,"the, at, this, that, sars-cov-2, is, for"
8605,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.145833333,"the, that, sars-cov-2, to, bat, and, pangolin"
8606,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.145833333,"the, to, bat, cov, ratg13, sars-cov-2, same"
8607,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.145833333,"that, the, and, bats, may, of, to"
8608,"Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.145833333,"based, on, the, of, in, wuhan, origin"
8609,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.145833333,"and, are, to, of, the, other, a"
8610,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.145833333,"sars-cov-2, in, of, and, that, the, for"
8611,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.145833333,"that, and, for, sars-cov-2, the, between, in"
8612,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.145833333,"has, sars-cov-2, and, with, the, of, virus"
8613,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.145833333,"however,, sars-cov-2, the, rbd, not, that, of"
8614,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.145833333,"the, virus, has, genome,, to, that, of"
8615,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.145833333,"to, sars-cov-2, be, virus, that, bats, the"
8616,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.145833333,"this, to, that, the, of, origin, be"
8617,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.145833333,"the, of, this, that, sars-cov-2, virus, has"
8618,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.145833333,"the, this, that, has, been, in, of"
8619,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.145833333,"at, this, is, the, sars-cov-2, that, for"
8620,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.145833333,"this, that, sars-cov-2, has, the, virus, of"
8621,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.145833333,"the, covid-19, pandemic, sars-cov-2, or, a, in"
8622,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.145833333,"the, of, to, identity, pangolin, and, bat"
8623,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.145695364,"the, to, in, a, of, as, group, researchers, reservoir, viruses, horseshoe, with, on, likely, sars, that, multiple, were, by, yunnan, province, and"
8624,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.145695364,"in, the, group, of, researchers, a, to, on, as, by, with, viruses, were, and, that, likely, sars, yunnan, reservoir, province, multiple, horseshoe"
8625,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.145454545,"found, the, of, sars-cov-2, is, to, a, bat"
8626,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.145454545,"the, sars-cov-2, to, a, of, is, found, bat"
8627,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.145454545,"genome, in, the, is, to, of, sars-like, covs"
8628,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.145454545,"the, that, in, a, to, from, animals, humans"
8629,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.145454545,"at, are, a, and, in, the, that, to"
8630,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.145454545,"that, of, from, to, humans, a, sars-cov-2, the"
8631,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.145454545,"in, the, a, that, from, animals, to, humans"
8632,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.145454545,"the, has, as, a, that, to, bat, and"
8633,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.145454545,"the, genome, and, bat, that, a, sequence, to"
8634,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.145454545,"that, the, with, in, market, were, a, of"
8635,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.145454545,"in, the, of, to, that, with, and, a"
8636,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.145454545,"have, by, and, to, the, of, sars-cov-2, is"
8637,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.145454545,"to, the, in, bats, and, a, wuhan,, china"
8638,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.145454545,"the, natural, reservoir, is, and, it, with, of"
8639,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.145454545,"that, the, of, were, in, with, a, market"
8640,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.145454545,"the, sequence, et, al.,, of, homology, with, sars-cov-2"
8641,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.145454545,"is, to, that, by, an, between, and, be"
8642,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.145454545,"of, the, covid-19, virus, isolated, in, with, and"
8643,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.145454545,"and, virus, with, the, covid-19, isolated, in, of"
8644,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.145454545,"the, genome, to, bat, and, that, sequence, a"
8645,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.145454545,"at, the, et, al.,, of, which, acid, sars-cov-2"
8646,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.145454545,"of, the, two, and, that, sars-cov-2, sequences, a"
8647,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.145454545,"studies, that, sars-cov-2, sequences, and, a, the, of"
8648,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.145454545,"a, of, the, has, been, that, to, virus"
8649,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.145454545,"that, the, of, in, to, with, a, and"
8650,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.145454545,"this, is, sars-cov-2, and, to, the, that, in"
8651,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.145454545,"in, the, of, is, to, sars-cov-2, that, virus"
8652,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.145454545,"to, the, that, sars-cov-2, a, of, humans, from"
8653,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.145454545,"sequence, homology, with, the, of, sars-cov-2, et, al.,"
8654,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.145454545,"the, acid, of, sars-cov-2, at, which, et, al.,"
8655,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.145454545,"the, species, serve, as, of, sars-cov-2, intermediate, and"
8656,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.145454545,"that, the, in, and, to, humans, intermediate, hosts"
8657,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.145454545,"may, by, of, to, and, the, for, sars-cov-2"
8658,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.145454545,"if, it, is, unlikely, that, the, covid-19, sars-cov-2"
8659,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.145454545,"to, sars-cov-2, in, the, is, result, of, natural"
8660,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.145454545,"sars-cov-2, of, species, and, the, serve, as, intermediate"
8661,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.145454545,"that, are, the, all, and, in, southern, china"
8662,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.145454545,"it, is, unlikely, that, sars-cov-2, if, the, covid-19"
8663,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.145454545,"at, an, infected, to, a, palm, as, civets, from, in, the, virus, sars, were, of, and"
8664,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.145454545,"in, the, of, palm, civets, as, an, sars, a, at, virus, from, infected, were, to, and"
8665,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.145454545,"in, the, a, that, are, to, at, and"
8666,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.145454545,"the, as, of, that, likely, to, bat, hosts"
8667,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.145454545,"the, is, result, of, natural, sars-cov-2, to, in"
8668,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.145454545,"the, of, this, that, sars-cov-2, is, in, for"
8669,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.145454545,"covid-19, a, the, that, from, animal, or, for"
8670,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.145454545,"that, and, intermediate, hosts, to, humans, the, in"
8671,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.145454545,"and, the, bats, to, a, in, wuhan,, china"
8672,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.145454545,"the, that, are, all, in, southern, china, and"
8673,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.145454545,"the, as, a, that, has, bat, and, to"
8674,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.145454545,"the, of, to, bat, likely, that, as, hosts"
8675,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.145454545,"the, that, virus, to, a, of, has, been"
8676,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.145454545,"the, natural, is, it, even, an, with, of"
8677,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.145454545,"the, of, and, have, sars-cov-2, is, to, by"
8678,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.145454545,"is, between, and, that, to, an, be, by"
8679,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.145454545,"sars-cov-2, be, of, natural, the, with, to, genetic"
8680,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.145454545,"the, is, to, sars-like, covs, in, of, genome"
8681,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.145454545,"the, of, sars-cov-2, to, may, for, and, by"
8682,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.145454545,"that, the, sequences, of, sars-cov-2, and, two, a"
8683,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.145454545,"in, the, is, to, that, sars-cov-2, and, this"
8684,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.145454545,"the, of, that, sars-cov-2, are, more, to, than"
8685,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.145454545,"studies, that, the, sequences, of, sars-cov-2, and, a"
8686,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.145454545,"to, that, the, of, are, more, sars-cov-2, than"
8687,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.145454545,"in, the, of, virus, is, to, that, sars-cov-2"
8688,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.145454545,"from, to, be, that, is, very, likely, sars-cov-2"
8689,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.145454545,"sars-cov-2, in, the, this, that, for, is, of"
8690,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.145454545,"that, the, covid-19, a, from, animal, or, for"
8691,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.145454545,"the, natural, reservoir, of, is, and, it, with"
8692,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.145454545,"even, the, with, of, natural, is, it, an"
8693,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.145454545,"that, sars-cov-2, is, very, likely, to, be, from"
8694,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.145454545,"the, genetic, of, sars-cov-2, with, to, be, natural"
8695,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.145299145,"the, of, a, in, species, to, that, sars, with, civets, as, intermediate, and, or, were, virus, for"
8696,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.145299145,"from, the, for, to, a, virus, that, with, this, as, and, human, adapted, sars, in, of, taken"
8697,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.145299145,"for, the, of, and, civets, were, intermediate, species, that, virus, a, in, sars, or, with, as, to"
8698,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.145299145,"for, the, of, and, that, virus, from, a, in, human, sars, taken, this, with, as, adapted, to"
8699,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.14516129,"the, sars-cov, palm, civet, of, bat, and, with, human"
8700,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.14516129,"the, genome, and, bat, that, sequence, ratg13, overall, to"
8701,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.14516129,"the, for, a, to, with, that, coronavirus, from, and"
8702,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.14516129,"early, cases, in, humans, lineage, the, of, that, sars-cov-2"
8703,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.14516129,"the, of, lineage, early, cases, that, sars-cov-2, humans, in"
8704,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.14516129,"that, may, have, a, of, one, to, the, sars-cov-2"
8705,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.14516129,"by, of, the, covid-19, cases, wuhan, december, with, huanan"
8706,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.14516129,"the, a, coronavirus, that, from, to, and, with, for"
8707,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.14516129,"the, a, that, from, jumped, to, humans, infected, and"
8708,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.14516129,"with, the, of, and, sars-cov, bat, palm, civet, human"
8709,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.14516129,"and, the, of, to, et, al.,, that, sars-cov-2, is"
8710,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.14516129,"species, of, that, likely, bats,, to, humans, by, and"
8711,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.14516129,"a, that, were, identified, wuhan, december, and, 2019, seafood"
8712,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.14516129,"of, that, the, a, from, these, intermediate, hosts, for"
8713,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.14516129,"genome, the, to, bat, ratg13, and, overall, sequence, that"
8714,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.14516129,"the, is, that, of, human, with, and, within, in"
8715,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.14516129,"the, sars-cov-2, and, of, et, al.,, is, to, that"
8716,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.14516129,"of, some, also, and, the, ability, to, species, through"
8717,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.14516129,"are, the, of, and, sars-cov-2-like, viruses, in, southern, between"
8718,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.14516129,"of, covid-19, cases, december, the, huanan, with, wuhan, by"
8719,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.14516129,"that, and, identified, were, a, seafood, wuhan, december, 2019"
8720,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.14516129,"in, the, of, is, that, with, human, and, within"
8721,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.14516129,"the, of, a, from, that, these, intermediate, hosts, for"
8722,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.14516129,"of, and, southern, sars-cov-2-like, viruses, are, between, in, the"
8723,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.14516129,"the, ability, of, to, species, through, also, and, some"
8724,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.14516129,"that, the, and, jumped, to, humans, from, infected, a"
8725,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.14516129,"humans, and, bats,, likely, that, of, to, species, by"
8726,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.14516129,"be, of, natural, the, emergence, and, to, sars-, cov-2"
8727,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.14516129,"one, the, of, that, a, sars-cov-2, may, have, to"
8728,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.14516129,"to, natural, emergence, the, of, sars-, cov-2, and, be"
8729,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.144927536,"from, a, of, in, bats, the, southeast, asia, and, that"
8730,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.144927536,"isolated, from, a, and, identity, with, sars-cov-2, has, in, the"
8731,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.144927536,"that, of, from, intermediate, a, coronavirus, in, pangolin, analysis, the"
8732,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.144927536,"analysis, in, the, of, a, coronavirus, from, pangolin, that, intermediate"
8733,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.144927536,"a, of, and, that, the, from, in, bats, asia, southeast"
8734,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.144927536,"a, coronaviruses, to, recombination, events, in, with, sars-cov-2, the, and"
8735,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.144927536,"to, sars-cov-2, a, recombination, in, the, and, events, with, coronaviruses"
8736,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.144927536,"has, a, identity, sars-cov-2, and, with, the, isolated, from, in"
8737,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.144736842,"a, and, amino, acid, sars-cov-2, spike, other, to, be, in, the"
8738,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.144736842,"is, a, and, can, be, as, to, that, coronavirus, in, bats"
8739,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.144736842,"as, it, was, the, of, that, suggested, may, have, in, a"
8740,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.144736842,"bats, a, coronavirus, as, is, can, and, be, in, that, to"
8741,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.144736842,"the, amino, acid, sars-cov-2, spike, and, to, be, a, in, other"
8742,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.144736842,"it, was, suggested, that, the, in, may, have, as, a, of"
8743,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.144578313,"a, by, who, market, in, that, the, virus, closely, related, to, of"
8744,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.144578313,"is, that, bats, are, the, most, likely, reservoir, for, as, to, a"
8745,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.144578313,"a, of, market, in, that, by, the, who, to, virus, closely, related"
8746,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.144578313,"the, are, to, a, for, as, reservoir, is, most, likely, that, bats"
8747,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.144144144,"the, to, in, a, for, of, researchers, reservoir, is, on, likely, sars, that, virus, by, yunnan"
8748,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.144144144,"the, of, on, is, by, for, likely, reservoir, in, researchers, a, virus, to, sars, yunnan, that"
8749,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.144067797,"cases, and, at, the, huanan, market,, be, likely, that, or, for, of, sars-cov-2, in, this, a, by"
8750,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.144067797,"cases, the, huanan, market,, and, for, of, a, or, that, in, this, sars-cov-2, likely, be, by, at"
8751,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.142857143,"a, in, of, bats"
8752,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.142857143,"in, which, sars-cov-2, closely, related, to, pangolin"
8753,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.142857143,"coronaviruses, are, a, viruses, many"
8754,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.142857143,"the, of, virus, 2, human, and, this, within"
8755,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.142857143,"the, known, and, to, of"
8756,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.142857143,"animal, and, are, the, of"
8757,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.142857143,"the, of, to, species, be, and"
8758,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.142857143,"the, to, are, and"
8759,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.142857143,"sars-cov, and, many, have"
8760,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.142857143,"of, sars-cov-2, sars-cov, and, to"
8761,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.142857143,"the, similar, to, sars-, cov-2"
8762,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.142857143,"is, sars-cov-2, to, virus, in"
8763,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.142857143,"one, genome, sars-cov-2, than"
8764,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.142857143,"sars-cov-2, more, to, genome, than"
8765,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.142857143,"and, the, virus, from, to, humans,, possibly"
8766,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.142857143,"with, the, sars-cov-2, is, to, in, of"
8767,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.142857143,"sars-cov-2, be, a, of, coronavirus"
8768,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.142857143,"of, have, been, that, by"
8769,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.142857143,"that, have, been, by, a, of, sars-cov-2"
8770,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.142857143,"other, found, sars-cov-2, to, and, a, the, of"
8771,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.142857143,"a, genetic, that, sars-cov-2, by, the, virus"
8772,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.142857143,"all, coronaviruses, that, of, to, and"
8773,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.142857143,"coronaviruses, are, of, viruses, many"
8774,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.142857143,"of, that, to, the, bat, and"
8775,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.142857143,"the, sars-cov-2, with, to, natural"
8776,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.142857143,"the, as, host, sars-cov-2"
8777,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.142857143,"a, to, the, it, is"
8778,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.142857143,"t, is, that, sars-cov-2, the"
8779,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.142857143,"sars-cov-2, is, a, sequence, bat, to, 96.2%, that"
8780,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.142857143,"a, bat, of, sars-cov-2, genome, the"
8781,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.142857143,"a, viruses, are, the, of"
8782,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.142857143,"and, the, of, a, natural"
8783,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.142857143,"are, the, natural, reservoir, of, and, viruses"
8784,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.142857143,"the, of, a, and"
8785,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.142857143,"and, a, natural, of, the"
8786,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.142857143,"of, the, and, a, viruses"
8787,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.142857143,"are, and, a, the, of"
8788,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.142857143,"sars-cov-2, was, and, to, cov, the"
8789,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.142857143,"bat, cov, ratg13, to, sars-cov-2"
8790,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.142857143,"sars-cov-2, of, and, human-to-human, transmission"
8791,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.142857143,"of, and, known, to, the"
8792,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.142857143,"of, the, in, is, to, with, sars-cov-2"
8793,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.142857143,"the, sars-cov-2, to, in, of, is"
8794,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.142857143,"of, the, and, with, bat"
8795,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.142857143,"the, bat, and, sequence, with"
8796,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.142857143,"of, the, known, in, to, with"
8797,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.142857143,"to, in, with, sars-cov-2, the, bat, and"
8798,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.142857143,"of, to, genome, sequence, bat, in"
8799,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.142857143,"and, of, sars-cov-2, in, is, the, to"
8800,Bats are hosts of many coronaviruses,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.142857143,"are, of"
8801,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.142857143,"of, most, similar, to"
8802,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",Originating from reservoir of bat,0.142857143,"reservoir, of"
8803,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.142857143,"the, of, sars-cov-2, to, be, its"
8804,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.142857143,"to, that, the, of, origin, and, be"
8805,"Bats have been reported as being the rich source of 

coronaviruses",hese reservoirs are the bats,0.142857143,"bats, the"
8806,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",hese reservoirs are the bats,0.142857143,"are, bats, the"
8807,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",hese reservoirs are the bats,0.142857143,"the, reservoirs, are, bats"
8808,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.142857143,"the, of, a, has, in"
8809,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.142857143,"the, virus, an, is, to, that, of, and, coronavirus"
8810,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.142857143,"the, virus, for, a, of, to, with, that, coronavirus, and"
8811,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.142857143,"with, bats, appear, to, be, the, of, virus"
8812,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.142857143,"of, that, the, is, a, ace2, receptor, thus, as, for"
8813,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.142857143,"the, and, also, a, in, ability, to, ace2, that, are, of"
8814,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.142857143,"in, the, was, considered, and"
8815,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.142857143,"a, virus, to, the, is"
8816,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.142857143,"that, the, a, in, to, and"
8817,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.142857143,"is, a, sequence, and, to, 96.2%, that, in"
8818,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.142857143,"the, was, in, and, that, a"
8819,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.142857143,"the, that, is, a, virus"
8820,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.142857143,"from, as, intermediate, hosts, to, for, the"
8821,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.142857143,"the, of, sars-cov-2, bats, to"
8822,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.142857143,"that, is, animal, to, zoonotic"
8823,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.142857143,"on, in, the, of, suggested, that, were, likely"
8824,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.142857143,"of, covid-19, to, wuhan, the, market, were, exposed, in"
8825,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.142857143,"in, this, it, that, the, of"
8826,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.142857143,"be, a, of, sars-cov-2, coronavirus"
8827,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.142857143,"human-to-human, transmission, of, sars-cov-2, and"
8828,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.142857143,"a, the, sars-cov-2, and, to, is"
8829,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.142857143,"the, sars-cov-2, and, of, is, to"
8830,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.142857143,"the, be, a, of"
8831,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.142857143,"the, animal, of, is, a"
8832,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.142857143,"a, the, be, to, sars-cov-2"
8833,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.142857143,"the, of, a, ability, and"
8834,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.142857143,"the, that, of, has, been, by"
8835,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.142857143,"evolutionary, of, that, most, the, and"
8836,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.142857143,"t, has, been, that, species"
8837,Bats are hosts of many coronaviruses,"All human coronaviruses have animal origins, namely, natu- 

ral hosts",0.142857143,"hosts, coronaviruses"
8838,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.142857143,"of, the, and, sars-"
8839,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.142857143,"the, of, and, are"
8840,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.142857143,"natural, and, the, of"
8841,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.142857143,"to, the, from, as, intermediate, hosts, for"
8842,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.142857143,"sars-cov, and, to, the, natural, palm, as, intermediate, respectively"
8843,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",Bats are likely reservoir hosts for SARS-CoV-2,0.142857143,"bats, likely, reservoir, sars-cov-2"
8844,"Bats are natural hosts of many of the known  

coronaviruses",zoonotic origins of SARS-CoV-2 by natural evolution,0.142857143,"natural, of"
8845,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",zoonotic origins of SARS-CoV-2 by natural evolution,0.142857143,"natural, of, sars-cov-2"
8846,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.142857143,"the, zoonotic, origin, is, a"
8847,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.142857143,"is, sars-cov-2, a, coronavirus"
8848,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.142857143,"sars-cov-2, is, to, from"
8849,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.142857143,"other, and, outbreaks, respiratory, the, of"
8850,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.142857143,"the, was, to, animals"
8851,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.142857143,"the, was, to, and, in"
8852,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.142857143,"in, animals, and, to"
8853,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.142857143,"in, the, was, and"
8854,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.142857143,"in, the, bats,, other"
8855,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.142857143,"the, in, from, was, outbreak"
8856,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.142857143,"in, animals, humans, through"
8857,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.142857143,"the, is, of, bat"
8858,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.142857143,"the, analysis, of, that, sars-cov-2, is"
8859,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.142857143,"the, is, that, in"
8860,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.142857143,"the, that, sars-cov-2, bat, in"
8861,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.142857143,"the, of, bat, is, that"
8862,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.142857143,"in, is, sars-cov-2, the, of, protein"
8863,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.142857143,"the, shows, that, sars-cov-2, of"
8864,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.142857143,"that, the, of, to, with, and"
8865,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.142857143,"the, genome, of, that, to, bat, and"
8866,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.142857143,"sars-cov-2, is, that, with, to, the"
8867,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.142857143,"for, that, the, of"
8868,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","civet cats and raccoon dogs  

are the intermediate hosts",0.142857143,"and, are, hosts"
8869,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.142857143,"was, in, a, with, and, are, to, at, the"
8870,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.142857143,"to, the, of, sars-cov-2, bats"
8871,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.142857143,"are, to, the, of, sars-cov-2"
8872,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.142857143,"the, of, to, sars-cov-2, can"
8873,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.142857143,"sars-cov-2, be, the, and"
8874,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.142857143,"through, the, to, be, sars-cov-2, of"
8875,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.142857143,"sars-cov-2, from, is, in, this"
8876,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.142857143,"a, that, the, and, in"
8877,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.142857143,"in, the, a, and"
8878,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.142857143,"and, that, a, origin, the"
8879,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.142857143,"a, that, the, which, and"
8880,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.142857143,"the, in, and, that, a"
8881,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.142857143,"that, and, a, the, origin"
8882,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.142857143,"the, in, that, origin"
8883,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.142857143,"that, the, virus, was, a"
8884,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.142857143,"the, been, that, was, by"
8885,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.142857143,"to, sars-cov-2, could, from, a, in, and, south, been, coronaviruses"
8886,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.142857143,"sars-cov-2, a, and, in, an, animal, host"
8887,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.142857143,"sars-cov-2, from, humans, to, the"
8888,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.142857143,"of, the, that, sars-cov-2, to"
8889,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.142857143,"a, the, that, to, of"
8890,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.142857143,"the, to, sars-cov-2, from, of, a"
8891,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.142857143,"that, the, of, evidence, a, to"
8892,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.142857143,"that, sars-cov-2, a, the, result, of, from"
8893,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.142857143,"the, from, that, sars-cov-2, to, a"
8894,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.142857143,"that, the, sars-cov-2, and, has, arisen"
8895,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.142857143,"suggest, that, the, of, these"
8896,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.142857143,"of, that, the, bat, and, was"
8897,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.142857143,"of, the, that, sars-cov-2"
8898,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.142857143,"the, that, was, of"
8899,SARS-CoV-2 was created from SARS-CoV-2,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.142857143,"sars-cov-2, from"
8900,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.142857143,"the, of, from, that, this, at"
8901,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.142857143,"the, of, to, that, sars-cov-2, this"
8902,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.142857143,"the, host, of, sars-cov-2, intermediate"
8903,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.142857143,"the, sars-cov-2, to, through, of, be"
8904,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.142857143,"that, the, huanan, and, animals"
8905,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.142857143,"are, to, be, the, of"
8906,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.142857143,"of, the, known, to, huanan, market"
8907,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.142857143,"through, that, the, of, to"
8908,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.142857143,"presence, of, lineage, at, the, huanan, market"
8909,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.142857143,"to, are, closely, related, the"
8910,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.142857143,"a, in, the, that, to"
8911,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.142857143,"to, the, huanan, market, in"
8912,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.142857143,"the, huanan, and, this, is"
8913,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.142857143,"of, the, in, with, huanan, market"
8914,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.142857143,"the, presence, of, lineage, huanan, market, at"
8915,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.142857143,"et, al., by, a, of, virus, the"
8916,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.142857143,"other, the, outbreaks, of, and, respiratory"
8917,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.142857143,"in, the, were, to, human, more, closely, related, than"
8918,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.142857143,"animal, at, and, in, the, that"
8919,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.142857143,"the, at, that, sars-cov-2, in, animal"
8920,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.142857143,"had, a, in, their"
8921,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.142857143,"the, sars-, cov-2, lineage, only, from, in"
8922,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.142857143,"a, had, their, in"
8923,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.142857143,"sars-cov-2, is, a, or, that, evidence"
8924,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.142857143,"the, from, to, a, market, in"
8925,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.142857143,"the, to, that, in, animals, humans"
8926,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.142857143,"the, evidence, from, that, to, animals"
8927,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.142857143,"is, that, are, the, likely, for, as, to, a"
8928,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.142857143,"covid-19, is, to, in, wuhan"
8929,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.142857143,"is, evidence, that, the, was, of, a"
8930,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.142857143,"to, that, the, most, of, and, evidence, is"
8931,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.142857143,"she, have, to, the, of, evidence, animals, market, doesn’t, other, that, clearly"
8932,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.142857143,"that, the, of, market, to, animals, clearly, evidence, she, doesn’t, have, other"
8933,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.142857143,"the, has, to, coronavirus, bat"
8934,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.142857143,"the, was, and, on, that, a"
8935,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.142857143,"the, a, and, has, bat"
8936,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.142857143,"the, huanan, animals, that, and"
8937,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.142857143,"this, is, and, the, huanan"
8938,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.142857143,"and, all, of, coronaviruses, that, to"
8939,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.142857143,"that, zoonotic, and, of, to"
8940,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.142857143,"that, to, infect, a, of, and"
8941,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.142857143,"a, of, have, zoonotic, and, to, species, different"
8942,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.142857143,"and, from, animals, human, beings"
8943,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.142857143,"all, human, can, in, and"
8944,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.142857143,"and, from, animals, human, beings, in, have"
8945,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.142857143,"the, in, and, was, considered"
8946,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.142857143,"the, considered, of, and"
8947,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.142857143,"human, beings, animals, and, from"
8948,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.142857143,"is, to, and, human"
8949,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.142857143,"disease, is, and, very"
8950,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.142857143,"the, sequence, that, coronavirus, to"
8951,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.142857143,"that, the, a, was, and, to"
8952,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.142857143,"of, a, in, bats"
8953,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.142857143,"a, of, the, possible, with, bats"
8954,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.142857143,"the, of, in, bats"
8955,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.142857143,"the, of, a, in"
8956,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.142857143,"the, of, with, that, and, to"
8957,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.142857143,"the, to, in, market, wuhan,"
8958,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.142857143,"in, the, of, to, that, which, virus"
8959,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.142857143,"of, the, covid-19, in, with, december, mid-february"
8960,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.142857143,"coronavirus, the, of, is, virus, and, that, to, an"
8961,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.142857143,"from, the, has, coronavirus, which, 99%"
8962,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.142857143,"from, is, identical, to, the, which, that"
8963,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.142857143,"the, from, that, to, which, and"
8964,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.142857143,"that, a, was, the, sars-cov-2, and, is, to"
8965,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.142857143,"the, sars-cov-2, and, virus, is, to, that"
8966,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.142857143,"the, that, sars-cov-2, was, to, pangolin, virus"
8967,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.142857143,"the, from, that, to, humans,, and"
8968,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.142857143,"that, bats, be, the, sars-cov-2, using"
8969,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.142857143,"a, for, coronavirus, the, of, virus, and, with, that, to"
8970,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.142857143,"the, and, of, genome, virus, to, that, bat"
8971,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.142857143,"the, from, that, covid-19, to, which, and"
8972,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","Bats have been reported as being the rich source of 

coronaviruses",0.142857143,"the, bats, of"
8973,hese reservoirs are the bats,"Bats have been reported as being the rich source of 

coronaviruses",0.142857143,"the, bats"
8974,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Bats have been reported as being the rich source of 

coronaviruses",0.142857143,"the, reported, have, been, of"
8975,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Bats have been reported as being the rich source of 

coronaviruses",0.142857143,"have, bats, the, of"
8976,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.142857143,"a, to, the, sars-cov-2, from"
8977,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.142857143,"has, been, the, from"
8978,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.142857143,"has, a, sars-cov-2, with, the, from"
8979,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.142857143,"the, coronavirus, to, a"
8980,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.142857143,"the, has, been, identified, a, from, to"
8981,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.142857143,"have, been, to, the, sars-cov-2, has"
8982,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.142857143,"to, the, has, been, identified, from"
8983,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.142857143,"sars-cov-2, to, pangolin, a, the"
8984,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.142857143,"the, sars-cov-2, isolated, from, bat"
8985,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.142857143,"from, the, bat, with"
8986,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.142857143,"the, bat, isolated, from"
8987,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.142857143,"the, from, sars-cov-2, bat, coronavirus"
8988,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.142857143,"bat, ratg13, sars-cov-2"
8989,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.142857143,"the, sars-cov-2, identity, with"
8990,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.142857143,"that, sars-cov-2, a, by, the, virus, genetic"
8991,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.142857143,"that, the, of, a, and, to"
8992,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.142857143,"the, that, sars-cov-2, to, a, and"
8993,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.142857143,"the, of, sars-cov-2, by, pangolin-cov"
8994,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.142857143,"the, of, considered, and"
8995,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.142857143,"is, and, to, human"
8996,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.142857143,"to, the, and, is, be, intermediate"
8997,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.142857143,"the, of, is, to"
8998,"Bats are natural hosts of many of the known  

coronaviruses","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.142857143,"hosts, of, the"
8999,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.142857143,"the, of, and, bat"
9000,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.142857143,"the, of, to, is, bat"
9001,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.142857143,"is, the, to, be"
9002,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.142857143,"and, to, the, of"
9003,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.142857143,"to, and, be, considered"
9004,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.142857143,"to, the, and, be, possible, hosts"
9005,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.142857143,"between, and, the, of"
9006,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.142857143,"on, the, analysis, by, that, sars-cov-2, and"
9007,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.142857143,"studies, that, the, transmitted, to, humans, and"
9008,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.142857143,"which, to, that, of, sars-cov-2, based, on, and, sequences"
9009,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.142857143,"to, the, and, possibly, humans,, from, virus"
9010,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.142857143,"the, in, a, to, from, market"
9011,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.142857143,"the, virus, and, bats, to"
9012,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.142857143,"from, bats, to, the, virus"
9013,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.142857143,"the, virus, to, a, and, transmitted"
9014,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.142857143,"are, a, and, in, the, to"
9015,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.142857143,"that, to, in, bats, and, china, from"
9016,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.142857143,"and, from, animals, to, through, in, who, have"
9017,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.142857143,"the, to, virus, in, animals, and, naturally"
9018,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.142857143,"in, the, of, which, was, to, but, virus"
9019,"expended to make the simple point 

that COVID-19 had a natural origin.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.142857143,"to, that, covid-19"
9020,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.142857143,"covid-19, to, in"
9021,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.142857143,"a, that, the, virus, was"
9022,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.142857143,"that, a, was, the, of, evidence, is"
9023,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.142857143,"is, that, of, a"
9024,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.142857143,"the, that, in, to, animals, humans"
9025,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.142857143,"in, animals, to, the, virus, and, naturally"
9026,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.142857143,"that, the, virus, and, to"
9027,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.142857143,"in, the, that, virus, humans, were, to, and, more"
9028,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.142857143,"the, that, virus, in, animals, were"
9029,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.142857143,"to, that, natural, the, origin, and"
9030,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.142857143,"the, that, is, in"
9031,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.142857143,"to, the, and, is, sars-cov, mers-cov"
9032,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.142857143,"virus, to, the, is"
9033,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.142857143,"that, the, in, to, and"
9034,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.142857143,"the, that, is, virus"
9035,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.142857143,"and, to, the, virus"
9036,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.142857143,"the, reservoirs, sars-cov, and"
9037,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.142857143,"and, that, in, the"
9038,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",COVID-19 is a potential zoonotic disease,0.142857143,"a, potential"
9039,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.142857143,"was, and, in, seafood, december, 2019"
9040,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.142857143,"of, reported, the, huanan, seafood, market,"
9041,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.142857143,"in, the, of, was, and"
9042,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.142857143,"the, and, with, bat, sars-like"
9043,"�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.142857143,"cov, bat, and, the"
9044,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.142857143,"the, with, bat, cov"
9045,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.142857143,"the, of, be, to, that, and"
9046,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.142857143,"zoonotic, that, of, to, and"
9047,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.142857143,"and, the, virus, bats, to"
9048,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.142857143,"the, to, that, virus, and"
9049,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.142857143,"the, of, sequence, that, to, virus"
9050,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.142857143,"the, that, of, zoonotic, is"
9051,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.142857143,"that, believed, to, be"
9052,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.142857143,"that, is, to, be"
9053,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.142857143,"the, is, to, be, intermediate, and"
9054,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.142857143,"the, is, to, mers-cov, and, sars-cov"
9055,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.142857143,"of, the, and, identity, with, bat, human"
9056,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.142857143,"the, of, for, it, is, with, human, and, a"
9057,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.142857143,"the, reservoir, bats"
9058,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.142857143,"the, of, are"
9059,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.142857143,"that, the, sars-cov-2, is, to, bat"
9060,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.142857143,"revealed, that, the, genomic, bat, is"
9061,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.142857143,"the, to, that, related, sars-cov-2, bat"
9062,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.142857143,"a, the, of, possible, with, bats"
9063,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.142857143,"the, coronavirus, has, bat, to"
9064,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.142857143,"to, the, of, human, bat"
9065,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.142857143,"to, been, genome, the, sars-cov-2"
9066,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.142857143,"bat, coronavirus, to, sars-cov-2"
9067,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.142857143,"the, sars-cov-2, has, of, to"
9068,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.142857143,"the, sars-cov-2, to, of"
9069,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.142857143,"of, to, sars-cov-2, the"
9070,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.142857143,"of, sars-cov-2, to, the"
9071,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.142857143,"sars-cov-2, is, to, a, and, the"
9072,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.142857143,"the, is, that, to, a, and, it"
9073,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.142857143,"that, by, a, to, and, the, for, sars-cov-2"
9074,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.142857143,"sars-cov-2, is, to, the, same, host, which"
9075,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.142857143,"to, recombination, the, key, of, rbd, transmission, with"
9076,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.142857143,"is, to, bat, sars-like"
9077,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.142857143,"all, human, in, can, and"
9078,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.142857143,"in, to, humans, intermediate"
9079,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.142857143,"analysis, that, sars-cov-2, the, with, of, and, similarity"
9080,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.142857143,"from, the, has, been"
9081,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.142857143,"the, has, been, of, that, from, bat"
9082,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.142857143,"to, sars-cov-2, is, virus, that, and, the"
9083,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.142857143,"the, virus, genome, of, to, that, and, bat"
9084,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.142857143,"genome, 96.2%, sequence, bat, that, and, sars-cov-2"
9085,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.142857143,"the, genetic, similarity, of, sars-cov-2, to"
9086,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.142857143,"the, of, that, sars-cov-2, to, bat, genome"
9087,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.142857143,"of, the, viruses, a, spike"
9088,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.142857143,"of, that, most, likely, sars-covs, by, bat, and"
9089,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.142857143,"bats, the, reservoir"
9090,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.142857143,"that, to, animal, is, zoonotic"
9091,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.142857143,"that, from, virus, is"
9092,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.142857143,"virus, is, to, that, human, a"
9093,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.142857143,"zoonotic, from, an, animal"
9094,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.142857143,"the, is, to, a, it"
9095,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.142857143,"a, is, the, to, virus"
9096,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.142857143,"the, virus, is, to"
9097,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.142857143,"the, virus, from, to"
9098,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.142857143,"the, to, it, is, for"
9099,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.142857143,"from, a, to, it, first"
9100,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.142857143,"to, the, sars-cov-2, humans, from"
9101,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.142857143,"related, the, are, closely, to"
9102,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.142857143,"the, sars-cov-2, are, humans"
9103,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.142857143,"sars-cov-2, from, are, to"
9104,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.142857143,"the, to, are, sars-cov-2"
9105,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.142857143,"sars-cov-2, bat, coronaviruses, to, the"
9106,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.142857143,"the, is, to, of"
9107,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.142857143,"is, the, of, to, coronaviruses"
9108,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.142857143,"the, of, to, is, bats"
9109,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.142857143,"the, of, to, in, bats"
9110,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.142857143,"isolated, from, in, is, the, of"
9111,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.142857143,"the, in, bats, is"
9112,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.142857143,"the, and, infected, from, animal"
9113,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.142857143,"the, from, market, in, to, and"
9114,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.142857143,"and, to, the, source, virus"
9115,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.142857143,"has, that, sars-cov-2, animal"
9116,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.142857143,"natural, origin, has, a, and"
9117,evidence suggests bats as its origin,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.142857143,"evidence, suggests, origin"
9118,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.142857143,"t, that, the, sars-cov-2, is"
9119,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.142857143,"the, from, animal, infected, and"
9120,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.142857143,"species, likely, to, of, sars-cov-2, intermediate, and"
9121,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.142857143,"that, and, to, humans, through, intermediate, of"
9122,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.142857143,"analyses, of, the, virus, and"
9123,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.142857143,"the, of, indicated, that, to, virus"
9124,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.142857143,"of, genomes, the, virus, covid-19, and"
9125,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.142857143,"of, covid-19, in, december, the, with, mid-february"
9126,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.142857143,"bats, the, of, virus, appear, be, with, to"
9127,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.142857143,"the, virus, from, bats, to"
9128,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.142857143,"analyses, of, the, virus, covid-19"
9129,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.142857143,"of, covid-19, virus, to, the"
9130,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.142857143,"the, that, are, to, and"
9131,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.142857143,"to, the, viruses, zoonotic, and"
9132,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.142857143,"as, intermediate, natural, to, sars-cov, and, the, palm, respectively"
9133,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.142857143,"to, the, that, sars-cov-2, of"
9134,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.142857143,"the, that, to, sars-cov-2, of"
9135,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.142857143,"the, to, coronavirus, that, sequence"
9136,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.142857143,"coronaviruses, to, sars-cov-2, the, that, is, of"
9137,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.142857143,"sars-cov-2, coronaviruses, to, the, of"
9138,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.142857143,"with, the, and, bat, of"
9139,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.142857143,"the, of, sars-, and"
9140,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.142857143,"the, of, bat, and, identity, with, human"
9141,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.142857143,"of, the, with, and, novel"
9142,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.142857143,"human, with, the, of"
9143,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.142857143,"the, bat, of, sars-"
9144,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.142857143,"and, bat, identity, the, of"
9145,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.142857143,"the, genome, of, that, and, to, bat"
9146,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.142857143,"that, the, of, and, novel, has"
9147,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.142857143,"sequences, of, in, identity, with"
9148,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.142857143,"on, the, analysis, and, that, sars-cov-2, by"
9149,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.142857143,"comparative, revealed, that, the, sars-cov-2, and, a, et"
9150,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.142857143,"that, sars-cov-2, not, a, laboratory"
9151,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.142857143,"genomic, revealed, that, is, bat, the"
9152,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.142857143,"analyses, the, virus, of, and"
9153,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.142857143,"of, the, covid-19, virus, and, genomes"
9154,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.142857143,"analyses, the, of, covid-19, virus"
9155,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.142857143,"a, the, to, that, in, and"
9156,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.142857143,"studies, the, and, that, transmitted, to, humans"
9157,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.142857143,"the, from, in, market, to, and"
9158,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.142857143,"the, from, a, seafood, market, and, to"
9159,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","the close relation  

between SARS coronavirus and 2019-nCoV",0.142857143,"between, and, the"
9160,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","the close relation  

between SARS coronavirus and 2019-nCoV",0.142857143,"the, between, and, sars"
9161,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","the close relation  

between SARS coronavirus and 2019-nCoV",0.142857143,"between, the, and"
9162,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.142857143,"seafood, in, was, december, 2019, and"
9163,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.142857143,"the, of, identical, to, sars-cov"
9164,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.142857143,"a, from, the, has, with, sars-cov-2"
9165,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.142857143,"of, the, in, and, sars-cov-2, a, with"
9166,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.142857143,"sars-cov-2, a, virus, between, the, and"
9167,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.142857143,"sars-cov-2, from, in, this, is"
9168,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.142857143,"sars-cov-2, in, from, a, bat"
9169,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.142857143,"is, that, sars-cov-2, a, virus, from"
9170,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.142857143,"is, bat, from, in"
9171,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.142857143,"from, that, sars-cov-2, a, bat"
9172,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.142857143,"bat, is, sars-cov-2"
9173,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.142857143,"on, the, of, that, were, in, suggested, likely"
9174,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.142857143,"of, the, analysis, that, sars-cov-2"
9175,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.142857143,"of, the, novel, and, with"
9176,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.142857143,"the, of, that, sars-cov-2, with, and, a"
9177,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.142857143,"a, with, two, and, sars-cov-2, the, genome"
9178,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.142857143,"sars-cov-2, humans, are, the"
9179,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.142857143,"are, the, hosts, of"
9180,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.142857143,"sars-cov-2, and, the, of"
9181,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.142857143,"the, of, and, sars-cov-2"
9182,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.142857143,"the, are, to, be, of"
9183,"This suggests that the BANAL series may be able to directly infect  

humans.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.142857143,"the, may, be, to"
9184,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.142857143,"the, bats, are, likely, hosts"
9185,zoonotic origins of SARS-CoV-2 by natural evolution,"Bats are natural hosts of many of the known  

coronaviruses",0.142857143,"of, natural"
9186,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","Bats are natural hosts of many of the known  

coronaviruses",0.142857143,"the, of, bats"
9187,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Bats are natural hosts of many of the known  

coronaviruses",0.142857143,"the, of, hosts"
9188,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Bats are natural hosts of many of the known  

coronaviruses",0.142857143,"the, of, bats, hosts"
9189,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.142857143,"that, sequence, sars-cov-2, is, 96.2%, to, a, bat"
9190,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.142857143,"a, is, to, that, in, 96.2%, sequence, and"
9191,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.142857143,"the, comparative, et, revealed, that, sars-cov-2, and, a"
9192,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.142857143,"is, considered, to, the"
9193,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.142857143,"is, to, pangolin"
9194,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.142857143,"the, has, which, 99%, coronavirus, from"
9195,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.142857143,"a, that, infect, of, to, and"
9196,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.142857143,"and, the, virus, transmitted, to, a"
9197,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.142857143,"a, it, that, the, and, to, is"
9198,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.142857143,"the, and, of, virus, is, to, that"
9199,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.142857143,"it, has, been, the, and, to, that, infect"
9200,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.142857143,"it, is, that, of, a"
9201,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.142857143,"the, hypothesis, of, has, a, and"
9202,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.142857143,"to, the, that, a, of"
9203,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.142857143,"in, a, that, the, to"
9204,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.142857143,"a, of, to, that, the"
9205,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.142857143,"a, of, in, to, the"
9206,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.142857143,"of, was, to, the, in"
9207,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.142857143,"of, the, with, similar, to, sars-, cov-2, in"
9208,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.142857143,"are, closely, related, to"
9209,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.142857143,"and, are, to, sars-cov-2."
9210,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.142857143,"be, a, of, the"
9211,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.142857143,"these, suggest, that, the, of"
9212,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.142857143,"that, the, of, a"
9213,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.142857143,"a, that, the, of"
9214,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.142857143,"suggest, that, may, a, of, the"
9215,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.142857143,"the, results, of, that, a"
9216,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.142857143,"be, the, host, of"
9217,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.142857143,"of, the, with, human"
9218,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.142857143,"the, of, with, human"
9219,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.142857143,"the, of, patients, with, huanan, seafood, in, hubei"
9220,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.142857143,"huanan, seafood, market,, the, reported, of"
9221,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.142857143,"in, the, to, huanan, market"
9222,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.142857143,"is, covid-19, in, wuhan, to"
9223,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.142857143,"covid-19, december, to, wuhan, the, huanan, market, in"
9224,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.142857143,"the, was, to, cov, and, sars-cov-2"
9225,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.142857143,"sars-cov-2, was, to, and"
9226,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.142857143,"of, sars-cov-2, was, to, the"
9227,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.142857143,"to, the, of, betacoronavirus, bats, and, sars-cov-2"
9228,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.142857143,"to, the, sars-cov-2, a, of, from"
9229,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.142857143,"the, was, in, rhinolophus, yunnan"
9230,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.142857143,"viruses, closely, related, in"
9231,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.142857143,"a, the, that, in, and, was"
9232,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.142857143,"on, the, was, a, that, and"
9233,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.142857143,"the, was, taken, a, and, of, on"
9234,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.142857143,"has, the, of, in"
9235,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.142857143,"of, the, been, in"
9236,zoonotic origins of SARS-CoV-2 by natural evolution,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.142857143,"of, sars-cov-2, natural"
9237,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.142857143,"the, a, from, as"
9238,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.142857143,"the, origin, of, sars-cov-2"
9239,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.142857143,"sars-cov-2, closely, related, to, pangolin, in, which"
9240,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.142857143,"to, sars-cov-2, virus, that, was, the, pangolin"
9241,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.142857143,"in, but, to, of, the, virus, which, was"
9242,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.142857143,"that, the, virus, of, sequence, to"
9243,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.142857143,"indicated, that, the, virus, of, to"
9244,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.142857143,"that, of, to, found, in, pangolin, sars-cov-2, analysis, the"
9245,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.142857143,"of, the, in, that, which, was"
9246,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.142857143,"that, of, pangolin, virus, similar, to, the, sars-cov-2"
9247,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.142857143,"sars-cov-2, to, in, the, ratg13, pangolin, which"
9248,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.142857143,"the, of, that, sars-cov-2, to, ratg13, pangolin"
9249,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","this one jumped from bats origin  

into humans",0.142857143,"from, bats, humans"
9250,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.142857143,"a, coronavirus, the, to"
9251,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.142857143,"a, the, was, to, laboratory"
9252,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.142857143,"these, studies, have, a, of, the, as"
9253,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.142857143,"of, a, the, to, which, covs, and"
9254,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.142857143,"in, the, of, has, a"
9255,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.142857143,"the, a, has, bat, and"
9256,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.142857143,"the, of, bat, and"
9257,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.142857143,"and, the, has, of, bat"
9258,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.142857143,"of, and, bat, a, in, the"
9259,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.142857143,"also, that, bats, are, hosts, for"
9260,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.142857143,"that, bats, are, hosts, for, sars-cov"
9261,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.142857143,"zoonotic, viruses, to, the, and"
9262,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.142857143,"in, the, of, for, to, sars-cov-2, and"
9263,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.142857143,"and, to, in, the, of"
9264,"zoonotic corona- 

viruses have become an increasing threat to human health,","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.142857143,"zoonotic, viruses, threat, to"
9265,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.142857143,"in, pangolins, were, because"
9266,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.142857143,"the, most, to, as, of, bat"
9267,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.142857143,"the, of, most, to, as, bat"
9268,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.142857143,"is, the, to, sars-cov-2, covid-19"
9269,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.142857143,"that, the, covid-19, to, wuhan, of"
9270,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.142857143,"the, genome, sars-cov-2, been, to"
9271,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.142857143,"the, virus, to, sars-cov-2, prior"
9272,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.142857143,"2, to, sars-cov-, the, genome, and, provide"
9273,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.142857143,"to, sars-cov-2, in, the"
9274,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.142857143,"that, related, to, sars-cov-2, in"
9275,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.142857143,"that, in, the, sars-cov-2"
9276,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.142857143,"2, human, and, of, within, this, the, virus"
9277,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.142857143,"a, for, the, of, is, and, it, with, human"
9278,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.142857143,"sars-cov-2, to, the, for, in, and, of"
9279,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.142857143,"the, of, sars-cov-2, to, it, is, for, and"
9280,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.142857143,"to, sars-cov-2, in, the, this, that, for, is, of"
9281,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.142857143,"a, of, the, has, been, often, that, to, virus"
9282,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.142857143,"to, that, the, of, and, for, more, sars-cov-2, than"
9283,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.142857143,"in, this, it, that, the, and, of"
9284,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.142857143,"to, this, that, sars-cov-2, has, the, virus, of"
9285,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.142857143,"found, in, the, analysis, of, that, sars-cov-2, to, pangolin"
9286,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.142857143,"identity, in, sequences, with, of"
9287,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.142857143,"the, of, coronaviruses, which, sars-cov-2"
9288,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.142857143,"in, two, of, genome, sequences, and, which"
9289,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.142857143,"a, similarity, with, sars-cov-2"
9290,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.142857143,"sars-cov-2, a, virus, that, found, with"
9291,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.142857143,"of, sars-cov-2, has, that, a"
9292,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.142857143,"sars-cov-2, is, that, to, the"
9293,"expended to make the simple point 

that COVID-19 had a natural origin.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.142857143,"to, the, that"
9294,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.142857143,"the, is, to"
9295,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.142857143,"is, that, sars-cov-2, to"
9296,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.142857143,"is, sars-cov-2, to, the, that"
9297,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.142857143,"the, is, to, sars-cov-2, that"
9298,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.142857143,"virus, from, to, the"
9299,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.142857143,"to, the, from, virus, with"
9300,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.142857143,"is, a, of, animal, the"
9301,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.142857143,"has, been, that, the, of, by"
9302,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.142857143,"the, a, is, zoonotic, origin"
9303,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.142857143,"is, that, the, zoonotic, of"
9304,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.142857143,"the, is, of, a, zoonotic, origin"
9305,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.142857143,"of, that, the, is, origin, a, animal"
9306,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.142857143,"of, the, been, that, by"
9307,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.142857143,"that, the, of, origin, is, yet"
9308,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.142857143,"the, of, pangolin-cov, is, sars-cov-2, that"
9309,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.142857143,"the, of, in, has"
9310,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","bats are also important reservoir species for a great 

range of coronaviruses",0.142857143,"also, a, are, for"
9311,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.142857143,"reported, the, to, and, in, sars-cov-2"
9312,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.142857143,"the, in, of, an, to, sars-cov-2"
9313,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.142857143,"with, the, and, bat, sequence"
9314,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.142857143,"the, from, bat, with"
9315,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.142857143,"sars-cov-2,, sequence, of, s, than"
9316,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.142857143,"the, of, that, sars-cov-2, a, in, animal, for"
9317,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.142857143,"the, that, to, infect, and, it, has, been"
9318,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.142857143,"the, was, to, a, laboratory"
9319,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.142857143,"in, reported, to, sars-cov-2, and, the"
9320,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.142857143,"the, in, to, that, sars-cov-2, was"
9321,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.142857143,"the, in, and, that, sars-cov-2, a"
9322,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.142857143,"that, sars-cov-2, to, and, a, the"
9323,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.142857143,"study, sars-cov-2, a, the, and"
9324,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.142857143,"that, the, sars-cov-2, a, laboratory"
9325,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.142857143,"sars-cov-2, to, be, a, the"
9326,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.142857143,"of, and, species, to, be, the"
9327,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.142857143,"the, of, for, it, is, to, sars-cov-2, and"
9328,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.142857143,"the, as, a, from"
9329,"atural  

selection in an animal host before zoonotic  

transfer;","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.142857143,"an, host, zoonotic"
9330,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.142857143,"to, the, from, zoonotic, a"
9331,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.142857143,"evidence, to, the, that, a, of"
9332,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.142857143,"a, of, to, that, the, and"
9333,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.142857143,"with, the, known, to, in, of"
9334,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.142857143,"the, huanan, market, known, to, of"
9335,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.142857143,"the, animal, in, to, and"
9336,Wet Market animals maintained in poor conditions,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.142857143,"in, poor, conditions"
9337,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.142857143,"the, to, sars-cov-2, in, and"
9338,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.142857143,"in, were, to, animal"
9339,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.142857143,"the, sars-cov-2, at, and, to"
9340,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.142857143,"the, outbreak, was, in, from"
9341,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.142857143,"at, that, the, of, from, this"
9342,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.142857143,"in, the, that, of, samples, 2020, taken, from, market"
9343,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.142857143,"the, in, of, that, this, was"
9344,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.142857143,"in, the, of, was, market"
9345,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.142857143,"sars-cov-2, to, coronavirus, bat"
9346,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.142857143,"ratg-13, to, sars-cov-2, in"
9347,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.142857143,"sars-cov-2, could, been, from, to, a, and, coronaviruses, in, south"
9348,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.142857143,"from, and, it, to, the, of, that, suggested, sars-cov-2, been, in, a"
9349,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.142857143,"of, the, cleavage, site, in, a, furin, to, that, events"
9350,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.142857143,"the, that, sars-cov-2, a, result, of, from"
9351,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.142857143,"covid-19, a, the, that, sars-cov-2, from, pandemic, or"
9352,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.142857143,"is, sars-cov-2, of, a, related"
9353,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.142857143,"of, covid-19, virus, is, to, the"
9354,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",Coronaviruses account for over 30% of the world’s viruses.,0.142857143,"of, the, for"
9355,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.142857143,"the, of, sars-cov-2, coronaviruses"
9356,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.142857143,"of, animal, and, the"
9357,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.142857143,"the, as, for"
9358,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.142857143,"the, of, and, animal"
9359,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.142857143,"and, likely, of, sars-cov-2, to, intermediate, species"
9360,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.142857143,"as, to, the, of, most, bat"
9361,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.142857143,"the, to, most, sars-cov-2, bat, and"
9362,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.142857143,"bats, the, likely, of, sars-cov-2"
9363,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.142857143,"the, that, sars-cov-2, in, bat"
9364,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.142857143,"that, sars-cov-2, related, to, bat, the"
9365,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.142857143,"the, most, to, sars-cov-2, bat, and"
9366,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.142857143,"the, most, closely, related, to, bat"
9367,The COVID-19 most likely developed from bat origin coronaviruses,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.142857143,"the, most, bat, coronaviruses"
9368,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.142857143,"and, in, all, closely, related, the"
9369,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.142857143,"and, in, to, closely, related, that, the, are, sars-cov-2"
9370,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.142857143,"in, were, to, and, the"
9371,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.142857143,"the, and, viruses, in, southern, china, for"
9372,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.142857143,"the, virus, to, and, sars"
9373,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.142857143,"to, the, in, and, of"
9374,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.142857143,"of, in, and, to, the"
9375,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.142857143,"and, bat, to, the, of"
9376,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.142857143,"the, of, a, and, in, bat"
9377,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.142857143,"are, a, other, closely, related, to, recombination, events, in, with, the, bat, and"
9378,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.142857143,"the, are, to, in, a, for, of, as, viruses, together, with, is, that, bats, infected, virus, and, other"
9379,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.142857143,"in, the, a, was, are, to, at, and, with"
9380,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.142857143,"a, the, sars-cov-2, genome, with, and, two"
9381,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.142857143,"banal, viruses, closely, related, to, the"
9382,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.142857143,"sars-cov-2., is, and, to, the, that"
9383,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.142857143,"the, rbd, of, is, to, that"
9384,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.142857143,"is, that, the, likely, reservoir, for, similar, to, a"
9385,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.142857143,"through, the, that, to, of"
9386,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.142857143,"the, to, have, that, with, of"
9387,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","This suggests that the BANAL series may be able to directly infect  

humans.",0.142857143,"to, be, the, may"
9388,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.142857143,"human, viruses, in, to, than"
9389,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.142857143,"he, from, in, is, the, of"
9390,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.142857143,"of, the, spike, viruses, a"
9391,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.142857143,"the, banal, viruses, closely, related, to"
9392,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.142857143,"sars-cov-2, the, for, and, of"
9393,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.142857143,"the, to, most, closely, related, bat"
9394,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.142857143,"the, of, to, bat, is, as"
9395,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.142857143,"the, related, to, after, is, most"
9396,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.142857143,"is, the, to, in, virus"
9397,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.142857143,"prior, to, virus, the, sars-cov-2"
9398,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.142857143,"with, the, and, sars-cov-2, to, bat, in"
9399,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.142857143,"and, the, bat, to, are, a, closely, related, with, other, in, recombination, events"
9400,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.142857143,"the, covid-19, is, be, in"
9401,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.142857143,"the, from, a, seafood, market, to, and"
9402,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.142857143,"the, was, and, on, taken, a, of"
9403,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.142857143,"the, and, to, wuhan, seafood, december, of"
9404,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.142857143,"to, the, of, from, by, a, with"
9405,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.142857143,"to, the, sars, were, as, for, known, and, a, in, of, sampled, species, from, three, antibodies., indicated, that, [sars], found, approximately"
9406,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.142857143,"a, virus, that, found, into, humans, with, to, the, for"
9407,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.142857143,"this, suggests, that, in, and, the, virus, for, of"
9408,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.142857143,"were, human, in, more, closely, related, to, the, than"
9409,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.142857143,"the, were, more, to, that, virus, in, and, humans"
9410,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.142857143,"the, of, a, to, in, and, were, virus, identical, at, was, palm, civet"
9411,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.142857143,"in, the, known, sars, of, approximately, from, found, that, three, sampled, for, as, antibodies., to, indicated, species, were, a, and, [sars]"
9412,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.142857143,"and, the, of, infected, to, viruses, are, as, a, together, bats, with, other, that, in, for, virus, is"
9413,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.142857143,"in, the, who-china, joint, and, january, that, of, 2020, were, to, huanan, all, market"
9414,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.142857143,"the, of, were, exposed, to, market, in, wuhan, covid-19"
9415,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.142857143,"covid-19, to, the, huanan, market, in, wuhan, december"
9416,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.142857143,"the, of, zoonotic, origin, is, a"
9417,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.142857143,"of, covid-19, is, to, the, and"
9418,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.142857143,"the, of, natural, origin, a, and"
9419,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.142857143,"the, animal, at, that, in, and"
9420,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.142857143,"are, and, the, to, a, in"
9421,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.142857143,"lineage, cases, and, environmental, at, the, huanan, seafood, that, of, in"
9422,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.142857143,"the, covid-19, is, in, seafood, market"
9423,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.142857143,"the, that, of, cases, huanan, seafood, and, lineage, in, environmental, at"
9424,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.142857143,"the, of, in, samples, taken, from, market, 2020, that"
9425,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.142857143,"the, huanan, market, that, in, who-china, joint, of, january, 2020, were, to, and, all"
9426,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.142857143,"the, sars-cov-2, with, that, is, to"
9427,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.142857143,"that, a, virus, found, with, sars-cov-2"
9428,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.142857143,"for, the, that, virus, into, a, found, humans, with, to"
9429,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","expended to make the simple point 

that COVID-19 had a natural origin.",0.142857143,"the, that, to"
9430,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","expended to make the simple point 

that COVID-19 had a natural origin.",0.142857143,"a, natural, that, to, the"
9431,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","expended to make the simple point 

that COVID-19 had a natural origin.",0.142857143,"the, covid-19, to"
9432,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","expended to make the simple point 

that COVID-19 had a natural origin.",0.142857143,"that, the, a, origin."
9433,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","expended to make the simple point 

that COVID-19 had a natural origin.",0.142857143,"that, the, to, a"
9434,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.142857143,"that, in, bats, and, to, from, china"
9435,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.142857143,"that, in, related, to, sars-cov-2"
9436,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.142857143,"that, bats, and, pangolins, sars-cov-2"
9437,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.142857143,"a, in, the, to, of"
9438,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.142857143,"sars-cov-2, an, animal, host, a, and, in"
9439,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.142857143,"the, that, sars-cov-2, a, virus"
9440,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.142857143,"show, that, is, not"
9441,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.142857143,"a, is, to, spike, the, that, not, human"
9442,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.142857143,"a, coronavirus, sars-cov-2, is"
9443,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.142857143,"is, that, a, of, it"
9444,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.142857143,"is, of, sars-cov-2, a, related"
9445,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.142857143,"a, that, is, of"
9446,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.142857143,"the, virus, is, that"
9447,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.142857143,"that, the, sars-, cov-2, is"
9448,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.142857143,"the, sars-, cov-2, is, that"
9449,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.142857143,"data, show, that, not, from"
9450,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","atural  

selection in an animal host before zoonotic  

transfer;",0.142857143,"zoonotic, an, host"
9451,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","atural  

selection in an animal host before zoonotic  

transfer;",0.142857143,"in, an, animal"
9452,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.142857143,"the, that, is, of, bat"
9453,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.142857143,"to, for, the, it, is"
9454,"Bats are natural hosts of many of the known  

coronaviruses","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.142857143,"bats, hosts, of, the"
9455,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.142857143,"the, of, to, as, is, bat"
9456,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.142857143,"that, the, bats, to, hosts, of"
9457,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.142857143,"the, to, that, is, of, bat, sars-, cov-2, as"
9458,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.142857143,"to, that, the, of, sars-, is, bats, likely, hosts"
9459,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.142857143,"the, which, is, to, identical, that, from"
9460,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.142857143,"the, spike, to, human, is, a, that, not"
9461,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.142857143,"of, the, that, sars-cov-2, is, to, coronaviruses"
9462,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.142857143,"in, the, of, for, is, to, that, sars-cov-2, this"
9463,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.142857143,"similarity, of, sars-cov-2, in, binding, is, the, for, to"
9464,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.142857143,"in, to, that, of, sars-cov-2, the, protein"
9465,"S1/S2 cleavage sites of coronaviruses are frequently modi- 

fied by insertions or deletions (indels) during evolution","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.142857143,"cleavage, of, by, insertions, deletions"
9466,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.142857143,"and, that, a, natural, of, the"
9467,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.142857143,"of, a, that, the, which, and"
9468,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.142857143,"the, of, sars-cov-2, can, to"
9469,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.142857143,"to, that, the, of, sars-cov-2, this"
9470,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.142857143,"in, an, of, to, sars-cov-2, the"
9471,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.142857143,"the, of, in, that, this, was"
9472,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.142857143,"we, sars-cov-2, the, rbd, in, that, of"
9473,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.142857143,"the, in, of, rbd, that, sars-cov-2, we"
9474,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","In the 

case of MERS, dromedaries were the principal host.",0.142857143,"in, were, host."
9475,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.142857143,"human, beings, have, in, animals, and, from"
9476,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.142857143,"through, have, in, and, to, from, who, animals"
9477,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.142857143,"a, that, the, covid-19, of"
9478,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.142857143,"the, of, that, a, bat, genome"
9479,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.142857143,"the, of, in, to, bats"
9480,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.142857143,"the, in, bats, and, to, of"
9481,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.142857143,"the, of, and, to, sars-cov"
9482,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.142857143,"evidence, the, that, to, from, animals"
9483,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.142857143,"the, which, to, that, and, from"
9484,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.142857143,"to, that, from, and, humans,, the"
9485,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.142857143,"the, covid-19, which, to, that, from, and"
9486,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.142857143,"to, that, the, sars-, and, evidence"
9487,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",The COVID-19 most likely developed from bat origin coronaviruses,0.142857143,"the, coronaviruses, most, bat"
9488,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",The COVID-19 most likely developed from bat origin coronaviruses,0.142857143,"the, likely, origin"
9489,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.142857143,"a, for, as, the, of, is, thus, that, ace2, receptor"
9490,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.142857143,"the, that, animal, of, origin, is, a"
9491,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.142857143,"of, covid-19, that, is, the, bat, for"
9492,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.142857143,"humans, and, that, of, to, through, intermediate"
9493,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.142857143,"that, the, wuhan, of, to, covid-19"
9494,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.142857143,"the, seafood, and, to, of, wuhan, december"
9495,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.142857143,"the, of, to, that, bats, hosts"
9496,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.142857143,"the, of, to, that, transmitted, bats"
9497,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.142857143,"are, coronaviruses, a, many, viruses"
9498,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.142857143,"viruses, are, of, coronaviruses, many"
9499,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.142857143,"in, and, to, animals"
9500,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.142857143,"in, humans, through, animals"
9501,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.142857143,"believed, that, be, to"
9502,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",Bats are hosts of many coronaviruses,0.142857143,"are, of, coronaviruses, many"
9503,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",Bats are hosts of many coronaviruses,0.142857143,"of, are"
9504,"All human coronaviruses have animal origins, namely, natu- 

ral hosts",Bats are hosts of many coronaviruses,0.142857143,"coronaviruses, hosts"
9505,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.142857143,"to, in, humans, intermediate"
9506,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.142857143,"animal, to, were, in"
9507,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.142857143,"the, in, wuhan,, to, market"
9508,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.142857143,"to, covid-19, in"
9509,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.142857143,"in, is, the, covid-19, be"
9510,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.142857143,"the, is, covid-19, seafood, market, in"
9511,"expended to make the simple point 

that COVID-19 had a natural origin.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.142857143,"to, the, covid-19"
9512,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.142857143,"the, to, be"
9513,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.142857143,"that, of, have, been, by"
9514,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.142857143,"that, the, was, been, by"
9515,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.142857143,"the, of, in, been"
9516,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.142857143,"in, the, of, which, that, was"
9517,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.142857143,"the, that, of, been, by"
9518,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.142857143,"of, that, most, the, was"
9519,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.142857143,"most, of, similar, to"
9520,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.142857143,"that, and, the, of, most, evolutionary"
9521,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.142857143,"and, that, the, bat, was, of"
9522,"According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.142857143,"to, is, sars-like, bat"
9523,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.142857143,"to, the, of, covid-19, virus"
9524,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.142857143,"the, covid-19, is, of, to, virus"
9525,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.142857143,"the, covid-19, and, is, of, to"
9526,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.142857143,"of, that, the, covid-19, is, bat, for"
9527,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.142857143,"most, of, the, that, was"
9528,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.142857143,"was, that, the, virus, is, to, of, sars-like"
9529,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.142857143,"the, of, that, is, virus, for"
9530,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.142857143,"the, is, and, it, to, of"
9531,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.142857143,"the, for, and, viruses, in, southern, china"
9532,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.142857143,"the, were, that, virus, in, animals"
9533,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.142857143,"in, the, hubei, of, with, patients, huanan, seafood"
9534,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.142857143,"patients, in, wuhan, china, the, of"
9535,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.142857143,"have, that, the, of, with, to"
9536,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.142857143,"in, was, to, that, of, the"
9537,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.142857143,"studies, have, the, of, a, as, these"
9538,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.142857143,"that, natural, of, the, is"
9539,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.142857143,"that, the, is, or"
9540,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.142857143,"from, in, sars-, cov-2, only, lineage, the"
9541,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.142857143,"the, isolated, from, bat"
9542,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.142857143,"from, is, in, bat"
9543,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.142857143,"the, lineage, isolated, in, from, is"
9544,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.142857143,"in, can, the, between, and, of, bat"
9545,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.142857143,"to, the, from, bats, humans"
9546,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.142857143,"the, closely, related, all, in, and"
9547,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.142857143,"in, the, of, palm, was, a, at, virus, were, identical, to, and, civet"
9548,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.142857143,"the, was, in, and"
9549,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.142857143,"the, and, a, in"
9550,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.142857143,"in, the, was, and, of"
9551,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.142857143,"of, the, patients, in, between, and"
9552,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.142857143,"a, between, and, the, of, in"
9553,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.142857143,"a, the, was, and, in"
9554,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.142857143,"the, of, in, market, was"
9555,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.142857143,"in, a, the, of"
9556,The FCS of SARS-CoV-2 was not bioengineered—full stop.,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.142857143,"the, of, was"
9557,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.142857143,"of, the, in, and, a"
9558,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.142857143,"the, first, was, in"
9559,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.142857143,"a, between, the, and"
9560,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.142857143,"the, lineage, is, isolated, from, in"
9561,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.142857143,"and, pangolins, have, the, from, in, wildlife"
9562,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.142857143,"and, of, sars-cov-2, in, their, is, the, viruses"
9563,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.142857143,"the, sars-cov-2, protein, is, in, of"
9564,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.142857143,"he, is, from, in, the, of"
9565,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.142857143,"is, on, the, in, receptor, binding, protein, from"
9566,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.142857143,"pangolins, were, because, in"
9567,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.142857143,"the, have, in, pangolins, from, wildlife, and"
9568,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.142857143,"may, have, in, bats, or"
9569,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.",0.142857143,"provide, evidence, that, of"
9570,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.142857143,"that, the, of, a, covid-19"
9571,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.142857143,"after, the, most, related, to, is"
9572,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.142857143,"have, a, zoonotic, different, species, of, to, and"
9573,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.142857143,"a, identified, from, the, has, been, to"
9574,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.142857143,"has, been, that, the, of, from, bat"
9575,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.142857143,"and, that, most, likely, by, of, bat, sars-covs"
9576,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.142857143,"to, the, that, has, been, identified, by, from, and"
9577,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.142857143,"sars-cov-2, and, genome, sequence, 96.2%, that, bat"
9578,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.142857143,"ratg13,, has, with, 96.2%, identity, genome"
9579,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.142857143,"the, in, is, bats"
9580,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.142857143,"a, is, the, that, virus"
9581,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.142857143,"a, virus, that, the, sars-cov-2"
9582,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.142857143,"the, that, sars-cov-2, of, virus"
9583,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","zoonotic corona- 

viruses have become an increasing threat to human health,",0.142857143,"to, viruses, zoonotic, threat"
9584,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.142857143,"the, to, of, and"
9585,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.142857143,"the, virus, to, and"
9586,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.142857143,"the, virus, source, to, and"
9587,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.142857143,"and, the, virus, to, of"
9588,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.142857143,"the, of, virus, and, to"
9589,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.142857143,"the, of, virus, to, that, has, been, often, a"
9590,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.142857143,"the, in, bats,, other"
9591,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.142857143,"a, from, to, first, it"
9592,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.142857143,"is, that, sars-cov-2, to, a"
9593,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.142857143,"the, that, with, of, is, or, laboratory, an"
9594,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.142857143,"that, a, has, of, sars-cov-2"
9595,"expended to make the simple point 

that COVID-19 had a natural origin.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.142857143,"the, that, a, origin."
9596,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.142857143,"reservoir, possibility, not, the, of, that, sars-cov-2, been, a"
9597,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.142857143,"that, the, reservoir, sars-cov-2, a"
9598,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.142857143,"many, have, sars-cov, and"
9599,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.142857143,"the, and, sars-cov, reservoirs"
9600,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.142857143,"to, sars-cov-2, from, a, of, in, the, and, it, been, suggested, that"
9601,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.142857143,"reservoir, of, sars-cov-2, not, been, that, the, possibility, a"
9602,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.142857143,"it, that, the, reservoir, for, sars-cov-2, as, to, a"
9603,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","S1/S2 cleavage sites of coronaviruses are frequently modi- 

fied by insertions or deletions (indels) during evolution",0.142857143,"insertions, deletions, of, cleavage, by"
9604,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.142857143,"from, an, animal, zoonotic"
9605,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.142857143,"the, for, transmission, from"
9606,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.142857143,"that, sars-cov-2, has, animal"
9607,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.142857143,"sars-cov-2, bat, cov, to, the"
9608,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.142857143,"the, identical, to, sars-cov-2, cov"
9609,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.142857143,"the, origin, and, a, that"
9610,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.142857143,"and, the, of, that, a, natural"
9611,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.142857143,"is, that, of, the, natural"
9612,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.142857143,"that, and, a, the, origin, of"
9613,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.142857143,"with, the, of, that, an, or, laboratory, is"
9614,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.142857143,"a, of, and, the, ability"
9615,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.142857143,"has, a, natural, origin, and"
9616,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.142857143,"the, hypothesis, a, of, and, has"
9617,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.142857143,"the, and, of, a, natural, origin"
9618,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.142857143,"the, has, been, to, have, sars-cov-2"
9619,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.142857143,"is, to, origin, the, has, been, by, and"
9620,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.142857143,"from, in, is, the, receptor, binding, protein, on"
9621,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.142857143,"considered, to, be, and"
9622,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.142857143,"sars-cov-2, from, to, are"
9623,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.142857143,"sars-cov-2, was, and, to"
9624,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.142857143,"from, that, sars-cov-2, to, and"
9625,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.142857143,"ratg13, to, sars-cov-2"
9626,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.142857143,"was, to, that, sars-cov-2"
9627,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.142857143,"based, on, of, and, sequences, that, sars-cov-2, which, to"
9628,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.142857143,"one, than, sars-cov-2, genome"
9629,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.142857143,"the, that, from, wiv, provides, be"
9630,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.142857143,"identified, from, the, has, been, to"
9631,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.142857143,"the, has, been, identified, that, from, to, by, and"
9632,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.142857143,"been, by, and, to, the, origin, has, is"
9633,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.142857143,"provides, the, that, from, wiv, be"
9634,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.142857143,"sars-cov-2, to, with, the, natural"
9635,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.142857143,"the, of, its, be, to, sars-cov-2"
9636,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.142857143,"the, genetic, similarity, sars-cov-2, of, to"
9637,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.142857143,"the, of, coronaviruses, sars-cov-2"
9638,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.142857143,"in, the, was, to, of"
9639,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.142857143,"the, to, sars-cov-2, was, in, of"
9640,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.142857143,"of, these, to, which, was, in"
9641,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.142857143,"also, of, sars-cov-2, in, which, the, to"
9642,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.142857143,"this, that, are, the, more, origin, of, sars-cov-2, than"
9643,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.142857143,"the, origin, of, be, to, that, and"
9644,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.142857143,"most, that, the, of, and, evidence, is, to"
9645,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.142857143,"the, natural, origin, to, that, and"
9646,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.142857143,"the, that, of, yet, origin, is"
9647,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.142857143,"the, evidence, that, to, sars-, and"
9648,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.142857143,"sars-cov-2, be, that, bats, using, the"
9649,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.142857143,"suggest, that, pangolins, the, hosts, for, sars-cov-2"
9650,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.142857143,"suggest, that, sars-cov-2, the, or"
9651,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.142857143,"to, the, that, sars-cov-2, a, from"
9652,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.142857143,"the, coronavirus, from, bat, sars-cov-2"
9653,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.142857143,"sars-cov-2, from, a, that, bat"
9654,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.142857143,"sars-cov-2, and, bat, pangolin, to, the"
9655,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.142857143,"that, sars-cov-2, bats, and, pangolins"
9656,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.142857143,"bats, are, the, likely, hosts"
9657,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.142857143,"bats, also, that, are, hosts, for"
9658,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.142857143,"of, virus, that, is, to, the, sars-like, was"
9659,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.142857143,"a, to, the, are, likely, that, is, for, as"
9660,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.142857143,"the, is, for, likely, reservoir, a, similar, to, that"
9661,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.142857143,"is, that, a, sars-cov-2, to"
9662,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.142857143,"reservoir, sars-cov-2, that, the, a"
9663,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.142857143,"reservoir, as, it, to, for, the, that, sars-cov-2, a"
9664,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.142857143,"is, sars-cov-2, bat, to, the, that"
9665,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.142857143,"the, and, which, a, that"
9666,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.142857143,"a, to, bat, that, the, of"
9667,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.142857143,"the, of, covs, to, a, and, which"
9668,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.142857143,"and, the, of, which, that, a"
9669,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.142857143,"that, the, and, bat, sars, which"
9670,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.142857143,"that, to, and, a, the, of"
9671,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.142857143,"the, genome, of, sars-cov-2, a, bat"
9672,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.142857143,"to, bat, in, of, genome, sequence"
9673,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.142857143,"of, was, to, which, in, these"
9674,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.142857143,"similarity, to, sars-cov-2, in, the, for, binding, is, of"
9675,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.142857143,"viruses, of, the, sars-cov-2, in, their, is, and"
9676,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.142857143,"of, sars-cov-2, also, to, which, the, in"
9677,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.142857143,"the, binding, to, in, sars-cov-2, and"
9678,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.142857143,"sars-cov-2, and, ratg13, similarity, to, the, of"
9679,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.142857143,"sequences, of, two, and, which, in, genome"
9680,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.142857143,"in, that, are, hosts, for, sars-cov-2"
9681,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.142857143,"that, a, of, sars-cov-2, have, been, by"
9682,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.142857143,"of, a, virus, the, by, et, al."
9683,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.142857143,"a, that, the, sars-cov-2, and, for, to, by"
9684,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.142857143,"suggest, that, the, may, a, of"
9685,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.142857143,"the, of, that, sars-cov-2, to, similar, pangolin, virus"
9686,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.142857143,"this, that, natural, in, and, the, features, of"
9687,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.142857143,"sars-cov-2, to, have, the, re"
9688,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.142857143,"the, as, sars-cov-2"
9689,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.142857143,"the, of, a, and, viruses"
9690,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.142857143,"a, sars-cov-2, and, with, the, of, in"
9691,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.142857143,"a, that, the, and, in, sars-cov-2"
9692,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.142857143,"to, bat, cov, ratg13, sars-cov-2"
9693,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.142857143,"ratg13, bat, sars-cov-2"
9694,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.142857143,"sars-cov-2, is, bat"
9695,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.142857143,"pangolin, is, to"
9696,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.142857143,"sars-cov-2, to, ratg13"
9697,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.142857143,"bat, pangolin, cov"
9698,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.142857143,"the, of, is, that"
9699,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.142857143,"of, sars-cov-2, that, the"
9700,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.142857143,"is, that, the, sars-cov-2"
9701,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.142857143,"is, we, sars-cov-2, the, that"
9702,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.142857143,"the, of, is, sars-cov-2, that"
9703,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.142857143,"the, to, be, possible, hosts, and"
9704,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.142857143,"to, sars-cov-, 2, and, genome, provide, the"
9705,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.142857143,"that, sars-cov-2, has, arisen, and, the"
9706,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.142857143,"and, that, the, novel, has, of"
9707,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.142857143,"the, that, sars-cov-2, has, of, and"
9708,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.142857143,"the, of, that, sars-cov-2, from, bats"
9709,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.142857143,"the, and, to, sars-cov-2., is, that"
9710,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.142857143,"the, sars-cov-2, and, this, bat, pangolin"
9711,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.142857143,"this, that, in, pangolin, and, the"
9712,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same",0.142857143,"bat, cov, and, the"
9713,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.142857143,"the, sars-cov-2, same, to, host, which, is"
9714,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.142857143,"in, the, which, sars-cov-2, to, ratg13, pangolin"
9715,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.142857143,"have, to, sars-cov-2, the, re"
9716,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.142857143,"the, of, sars-, cov-2, to, bat, is, that, as"
9717,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.142857143,"the, shows, that, sars-cov-2, closest, with, of, and, to"
9718,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.142857143,"of, the, bat, sars-"
9719,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.142857143,"bat, cov, pangolin"
9720,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.142857143,"that, hosts, for, sars-cov-2, are, in"
9721,"the close relation  

between SARS coronavirus and 2019-nCoV","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.142857143,"the, between, sars, and"
9722,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.142857143,"that, the, which, bat, and, sars"
9723,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.142857143,"that, sars-cov-2, pangolin, cov, and, the"
9724,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.142857143,"the, sars-cov-2, is, same, and"
9725,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.142857143,"sars-cov-2, between, the, and, cov"
9726,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.142857143,"ratg13, is, the, bat, s, than"
9727,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.142857143,"that, sars-cov-2, with, bat, the"
9728,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.142857143,"with, bat, cov, the"
9729,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.142857143,"suggest, that, or, the, sars-cov-2"
9730,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.142857143,"the, bats, likely, of, sars-cov-2"
9731,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.142857143,"that, are, more, than, the, sars-cov-2, this, of, origin"
9732,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.142857143,"this, sars-cov-2, and, bat, pangolin, the"
9733,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.142857143,"this, pangolin, and, the, of"
9734,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.142857143,"the, probable, of, sars-cov-2"
9735,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.142857143,"the, sars-cov-2, same, with, and, but"
9736,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.142857143,"bats, may, have, or, in"
9737,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.142857143,"sars-cov-2, and, to, bats, the, of, betacoronavirus"
9738,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.142857143,"the, of, for, more, than, to, that, sars-cov-2, and"
9739,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.142857143,"the, of, patients, in, wuhan, china"
9740,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.142857143,"the, sars-cov-2, and, to, a, of, found, other"
9741,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.142857143,"are, the, of, a, and"
9742,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.142857143,"a, the, pangolin, to, sars-cov-2"
9743,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.142857143,"and, that, a, origin, of, the"
9744,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.142857143,"of, a, that, the, to, and"
9745,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.142857143,"that, the, sars-cov-2, and, cov, pangolin"
9746,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.142857143,"sars-cov-2, a, the, and, cov"
9747,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.142857143,"a, of, sars-cov-2, found, to, origin, that"
9748,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.142857143,"more, than, to, sars-cov-2, genome"
9749,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.142857143,"the, sars-cov-2, of, genome, to, that, bat"
9750,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.142857143,"sars-cov-2, with, pangolin-cov, and"
9751,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.142857143,"the, of, and, sars-cov-2, is, to"
9752,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.142857143,"the, identical, to, of, sars-cov"
9753,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.142857143,"is, the, of, to, sars-cov-2"
9754,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.142857143,"the, of, to, sars-cov, and"
9755,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.142857143,"identity, sars-cov-2, and, with, the, of"
9756,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.142857143,"of, the, and, sars-cov-2, with"
9757,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.142857143,"the, sars-cov-2, and, is, same"
9758,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.142857143,"and, the, same, but, sars-cov-2, with"
9759,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.142857143,"sars-cov-2, and, pangolin-cov, with"
9760,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.142857143,"sars-cov-2, the, bat-sl-cov, and"
9761,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.142857143,"with, the, sars-cov, sars-cov-2, of"
9762,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.142857143,"of, sars-cov-2, by, the, pangolin-cov"
9763,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.142857143,"of, the, sars-cov-2, with, sars-cov"
9764,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.142857143,"with, that, the, of, sars-cov-2, and, analysis, similarity"
9765,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.142857143,"transmission, from, the, for"
9766,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.142857143,"of, the, that, for"
9767,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.142857143,"the, and, that, in"
9768,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.142857143,"the, that, in, sars-cov-2"
9769,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.142857143,"the, that, sars-cov-2, in, and"
9770,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.142857143,"the, of, bat-sl-cov-2, that, sars-cov-2"
9771,"Bats have been reported as being the rich source of 

coronaviruses","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.142857143,"bats, have, the, of"
9772,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.142857143,"bats, sars-cov, that, are, hosts, for"
9773,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.142857143,"and, are, to, the"
9774,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.142857143,"sars-cov-2, to, are, the"
9775,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.142857143,"are, to, the, and"
9776,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.142857143,"sars-cov-2, and, to, the"
9777,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.142857143,"and, to, in, the"
9778,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.142857143,"in, and, are, to, sars-cov-2, the"
9779,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.142857143,"are, to, in, sars-cov-2, the, and"
9780,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.142857143,"and, sars-cov-2, in, binding, the, to"
9781,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.142857143,"in, to, sars-cov-2, the"
9782,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.142857143,"this, of, the, in, that, virus"
9783,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.142857143,"for, the, of, and, that, virus, in, this, suggests"
9784,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.142857143,"the, features, of, in, and, that, this, natural"
9785,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.142857143,"this, and, pangolin, the, that, in"
9786,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.142857143,"the, and, this, pangolin, of"
9787,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.142857143,"to, sars-cov-2, and, at, the"
9788,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.142857143,"of, the, that, sars-cov-2, virus"
9789,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.142857143,"with, the, and, to, that, sars-cov-2, of, shows, closest"
9790,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.142857143,"to, the, of, pangolin-cov, virus, with"
9791,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.142857143,"the, of, that, in, it, this"
9792,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.142857143,"in, the, of, it, that, and, this"
9793,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.142857143,"can, of, and, the, in, between, bat"
9794,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.142857143,"that, the, bats, transmitted, to, of"
9795,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.142857143,"that, the, of, sars-cov-2, from, bats"
9796,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.142857143,"that, sars-cov-2, the, bat-sl-cov-2, of, to"
9797,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.142857143,"bat-sl-cov-2, that, the, of, sars-cov-2"
9798,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.142857143,"of, to, the, in, which, that, virus"
9799,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.142857143,"of, the, that, pangolin-cov, sars-cov-2, is"
9800,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.142857143,"the, of, to, rbd, is, that"
9801,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.142857143,"the, sars-cov-2, to, identical, cov"
9802,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.142857143,"sars-cov-2, as, the, host"
9803,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.142857143,"as, the, for"
9804,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.142857143,"sars-cov-2, as, the"
9805,evidence suggests bats as its origin,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.142857143,"suggests, as"
9806,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.142857143,"the, of, virus, to, that, sars-cov-2, has, this"
9807,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.142857143,"the, key, recombination, to, with, rbd, of, transmission"
9808,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.142857143,"the, by, from, a, to, of, with"
9809,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.142857143,"the, with, of, virus, to, pangolin-cov"
9810,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.142857143,"the, origin, that, in"
9811,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.142857143,"in, the, was, first"
9812,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.142857143,"to, from, sars-cov-2, is"
9813,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.142857143,"is, that, be, to"
9814,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.142857143,"sars-cov-2, is, that, the, most"
9815,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.142857143,"the, sars-cov-2, probable, of"
9816,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.142857143,"the, of, be, and, animal, sars-cov-2"
9817,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.142857143,"the, of, sars-cov-2, intermediate, host"
9818,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.142857143,"the, sars-cov-2, and, be"
9819,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.142857143,"a, between, sars-cov-2, and, the, virus"
9820,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.142857143,"a, study, the, and, sars-cov-2"
9821,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.142857143,"between, and, be, the"
9822,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.142857143,"the, a, between, and"
9823,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.142857143,"the, between, sars-cov-2, and, cov"
9824,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.142857143,"sars-cov-2, cov, and, a, the"
9825,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.142857143,"the, sars-cov-2, and, bat-sl-cov"
9826,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.142857143,"the, sars-cov-2, animal, at, that, in"
9827,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.142857143,"this, in, the, of, that, sars-cov-2, virus"
9828,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.142857143,"sars-cov-2, in, a, of, animal, that, the, for"
9829,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.142857143,"of, virus, that, is, the, for"
9830,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.142857143,"that, sars-cov-2, a, the, covid-19, pandemic, or, from"
9831,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.142857143,"of, it, is, to, the, and"
9832,"bats are also important reservoir species for a great 

range of coronaviruses","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.142857143,"are, also, for, a"
9833,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.142857143,"found, that, sars-cov-2, to, a, origin, of"
9834,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.142857143,"has, genome, 96.2%, identity, with, ratg13,"
9835,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.142857143,"of, to, that, sars-cov-2, the"
9836,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.142857143,"to, sars-cov-2, in, the, that, protein, of"
9837,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.142857143,"the, was, to, that, in, of"
9838,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.142857143,"sars-cov-2, was, that, to"
9839,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.142857143,"to, a, of, in, the, that, furin, cleavage, site, events"
9840,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.142857143,"the, to, that, are, closely, related, sars-cov-2, in, and"
9841,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.142857143,"the, of, sars-, to, is, likely, that, bats, hosts"
9842,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.142857143,"s, sequence, sars-cov-2,, than, of"
9843,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.142857143,"s, the, bat, ratg13, is, than"
9844,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.142857143,"are, also, a, the, of, and, in, that, ability, to, ace2"
9845,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.142857143,"the, is, of, to, closely, related"
9846,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.142857143,"to, the, of, sars-, cov-2, is"
9847,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.142857143,"in, the, with, similar, to, of, sars-, cov-2"
9848,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.142857143,"sars-cov-2, to, coronaviruses, bat, the"
9849,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.142857143,"of, the, and, identity, bat"
9850,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.142857143,"the, sars-cov-2, to, bat, and, pangolin"
9851,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.142857143,"and, similarity, of, sars-cov-2, ratg13, the, to"
9852,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.142857143,"a, that, the, laboratory, sars-cov-2"
9853,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.142857143,"is, that, a, sars-cov-2, the"
9854,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.142857143,"is, that, or, the"
9855,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.141304348,"a, of, market, in, that, wild, tested, positive, for, the, being, to, virus"
9856,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.141304348,"in, a, of, to, the, virus, that, wild, being, market, for, tested, positive"
9857,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.141304348,"for, the, of, that, virus, palm, a, only, in, sars, or, with, to"
9858,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.141304348,"a, of, in, that, for, sars, with, palm, only, the, or, to, virus"
9859,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.141176471,"is, a, virus, that, its, into, contact, with, infected, to, the, for"
9860,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.141176471,"the, infected, to, a, with, that, into, contact, for, virus, is, its"
9861,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.141025641,"for, the, and, that, humans,, from, a, in, humans, with, to"
9862,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.141025641,"the, of, that, from, contained, a, only, in, suggests, humans, to"
9863,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.141025641,"lineage, cases, samples, the, that, spillover, of, sars-cov-2, in, from, a"
9864,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.141025641,"analysis, in, the, of, a, from, that, mammals, were, likely, for"
9865,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.141025641,"for, the, of, and, palm, a, sequence, human, with, out, as"
9866,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.141025641,"infected, from, in, the, wet, market, or, animals, source, may, contaminated"
9867,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.141025641,"the, of, china, have, a, live, in, animals, market, were, was"
9868,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.141025641,"in, a, of, the, likely, that, analysis, from, mammals, were, for"
9869,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.141025641,"for, the, of, were, intermediate, that, from, a, sequence, in, likely"
9870,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.141025641,"coronavirus, from, a, malayan, pangolin, with, sars-cov-2, intermediate, to, in, the"
9871,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.141025641,"is, that, bats, are, the, for, as, similar, to, a, bat"
9872,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.141025641,"in, the, a, humans,, that, from, to, humans, and, with, for"
9873,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.141025641,"from, in, humans, contained, only, the, of, suggests, that, a, to"
9874,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.141025641,"a, for, the, palm, out, as, of, and, sequence, with, human"
9875,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.141025641,"sequence, in, the, of, a, from, that, were, likely, intermediate, for"
9876,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.141025641,"contaminated, source, from, infected, or, animals, in, the, wet, market, may"
9877,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.141025641,"samples, from, cases, in, lineage, the, of, that, a, sars-cov-2, spillover"
9878,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.141025641,"was, the, in, china, have, market, live, animals, were, a, of"
9879,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.141025641,"from, to, intermediate, a, coronavirus, in, malayan, pangolin, with, sars-cov-2, the"
9880,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.141025641,"the, bat, to, similar, are, as, a, bats, that, for, is"
9881,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.14084507,"coronaviruses, found, in, which, to, of, sars-cov-2, and, amino, acid"
9882,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.14084507,"of, market, in, that, had, the, who, or, to, virus"
9883,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.14084507,"coronavirus, from, a, pangolin, and, identity, with, has, to, the"
9884,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.14084507,"samples, the, huanan, seafood, market,, that, for, of, sars-cov-2, from"
9885,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.14084507,"of, to, the, market, who, in, that, had, virus, or"
9886,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.14084507,"found, evidence, that, with, the, of, to, as, intermediate, host"
9887,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.14084507,"the, of, known, covid-19, cases, with, huanan, market, and, in"
9888,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.14084507,"of, cases, covid-19, with, and, the, huanan, market, in, known"
9889,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.14084507,"that, of, sars-cov-2, samples, from, the, huanan, seafood, market,, for"
9890,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.14084507,"would, be, a, in, the, that, sars-cov-2, from, or, for"
9891,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.14084507,"that, rhinolophus, bats, the, of, and, viruses, have, in, china"
9892,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.14084507,"viruses, the, have, in, bats, of, rhinolophus, and, that, china"
9893,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.14084507,"the, has, a, to, identity, with, coronavirus, from, pangolin, and"
9894,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.14084507,"a, pangolin, with, one, to, and, the, intermediate, hosts, sars-cov-2"
9895,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.14084507,"amino, acid, sars-cov-2, and, which, to, of, found, in, coronaviruses"
9896,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.14084507,"one, a, pangolin, and, with, sars-cov-2, intermediate, hosts, to, the"
9897,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.14084507,"the, would, be, that, or, for, sars-cov-2, in, from, a"
9898,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.14084507,"in, were, recently, found, to, be, that, of, coronavirus, sars-cov-2"
9899,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.14084507,"in, of, sars-cov-2, were, recently, found, to, be, coronavirus, that"
9900,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.14084507,"the, of, intermediate, host, that, found, evidence, with, as, to"
9901,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.140625,"the, of, was, a, found, that, identical, to, sequence"
9902,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.140625,"china, a, to, animal, in, wet, and, market, were"
9903,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.140625,"from, into, as, to, the, of, that, sars-cov-2, a"
9904,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.140625,"of, the, two, in, and, that, sars-cov-2, a, viruses"
9905,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.140625,"lineage, and, at, the, huanan, of, in, this, a"
9906,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.140625,"and, a, of, about, sars-cov-2, is, an, the, to"
9907,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.140625,"from, a, pangolin, and, sars-cov-2, intermediate, to, be, the"
9908,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.140625,"and, to, by, the, of, that, suggested, sars-cov-2, a"
9909,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.140625,"may, in, a, of, that, the, with, as, or"
9910,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.140625,"in, the, an, virus, from, infected, to, human, and"
9911,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.140625,"of, and, similar, viruses, are, bat, a, in, the"
9912,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.140625,"to, and, of, that, similar, viruses, ratg13, in, bat"
9913,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.140625,"a, genome, from, the, of, sars-like, covs, were, bats"
9914,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.140625,"sars-cov-2, in, a, of, and, that, the, with, for"
9915,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.140625,"that, and, for, sars-cov-2, to, than, the, in, with"
9916,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.140625,"it, has, been, in, the, and, to, that, evolution"
9917,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.140625,"and, from, in, were, to, the, of, bats, sars-cov-2"
9918,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.140625,"that, the, with, in, may, or, as, a, of"
9919,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.140625,"in, the, of, for, that, sars-cov-2, with, and, a"
9920,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.140625,"in, the, for, than, to, that, sars-cov-2, with, and"
9921,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.140625,"other, to, in, may, with, sars-cov-2, than, the, and"
9922,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.140625,"in, the, evolution, it, to, that, has, been, and"
9923,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.140625,"environmental, samples, the, that, for, of, sars-cov-2, in, from"
9924,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.140625,"the, of, coronaviruses, from, with, a, and, sars-cov-2, recombination"
9925,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.140625,"the, of, and, bat, a, in, viruses, are, similar"
9926,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.140625,"the, region, and, a, in, suggesting, bat, are, of"
9927,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.140625,"and, may, sars-cov-2, to, other, than, the, in, with"
9928,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.140625,"was, found, that, the, sequence, of, identical, to, a"
9929,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.140625,"the, virus, human, from, an, in, infected, to, and"
9930,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.140625,"the, sequence, of, more, than, to, and, both, in"
9931,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.140625,"this, a, and, of, lineage, at, the, huanan, in"
9932,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.140625,"environmental, samples, from, the, that, of, in, for, sars-cov-2"
9933,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.140625,"sars-cov-2, from, a, recombination, of, the, and, with, coronaviruses"
9934,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.140625,"in, the, of, to, both, and, more, sequence, than"
9935,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.140625,"were, to, a, and, wet, animal, market, in, china"
9936,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.140625,"to, sars-cov-2, be, a, from, and, the, pangolin, intermediate"
9937,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.140625,"to, the, that, sars-cov-2, as, a, of, into, from"
9938,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.140625,"a, of, to, suggested, that, sars-cov-2, by, the, and"
9939,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.140625,"have, that, the, reservoir, for, a, of, sars-cov, and"
9940,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.140625,"the, of, bats, were, a, genome, sars-like, covs, from"
9941,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.140625,"a, the, of, sars-cov-2, and, is, to, an, about"
9942,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.140625,"a, of, the, that, sars-cov-2, and, two, in, viruses"
9943,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.140625,"in, with, the, results, clustering, and, that, sars-cov-2, of"
9944,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.140625,"results, of, the, clustering, in, and, that, sars-cov-2, with"
9945,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.140625,"using, the, hierarchical, clustering, in, fig., that, are, sars-cov-2"
9946,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.140625,"that, sars-cov-2, are, to, pangolin, cov, and, the, of"
9947,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.140625,"in, the, using, hierarchical, clustering, fig., that, sars-cov-2, are"
9948,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.140625,"the, and, to, that, sars-cov-2, of, cov, pangolin, are"
9949,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.140625,"sars-cov, reservoir, and, for, the, of, that, have, a"
9950,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.140625,"in, from, of, bats, were, to, sars-cov-2, and, the"
9951,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.140625,"region, of, and, are, bat, suggesting, a, in, the"
9952,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.140625,"of, and, bat, that, in, ratg13, viruses, similar, to"
9953,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.140350877,"a, it, was, the, sars-cov-2, to, is, used"
9954,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.140350877,"a, was, that, the, sars-cov-2, also, is, by"
9955,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.140350877,"its, in, the, sequence, that, sars-cov-2, was, virus"
9956,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.140350877,"the, genome, sequence, that, was, to, bat, and"
9957,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.140350877,"a, coronavirus, in, the, with, that, to, of"
9958,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.140350877,"a, was, in, that, the, virus, is, to"
9959,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.140350877,"coronavirus, isolated, from, a, with, sars-cov-2, to, the"
9960,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.140350877,"and, to, be, the, of, bats, are, sars-cov-2"
9961,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.140350877,"sars-cov-2, that, its, through, contact, with, on, to"
9962,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.140350877,"that, the, in, and, jumped, humans, at, market"
9963,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.140350877,"that, the, of, evidence, a, was, and, to"
9964,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.140350877,"with, the, of, a, for, genome, from, and"
9965,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.140350877,"that, have, by, of, to, and, the, sars-cov-2"
9966,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.140350877,"the, and, market, that, jumped, humans, at, in"
9967,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.140350877,"in, animals, to, the, virus, genetic, bats, and"
9968,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.140350877,"genetic, the, virus, in, bats, and, to, animals"
9969,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.140350877,"a, the, was, it, is, used, to, sars-cov-2"
9970,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.140350877,"is, also, that, sars-cov-2, was, a, by, the"
9971,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.140350877,"the, of, virus, is, to, that, sars-cov-2, and"
9972,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.140350877,"and, similarity, of, between, sars-cov-2, is, the, to"
9973,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.140350877,"genome, the, was, to, bat, and, sequence, that"
9974,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.140350877,"the, coronaviruses, to, that, are, bat, in, and"
9975,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.140350877,"a, coronavirus, the, of, in, with, that, to"
9976,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.140350877,"that, sars-cov-2, was, the, virus, its, sequence, in"
9977,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.140350877,"a, by, china, the, virus, of, found, bats"
9978,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.140350877,"the, for, a, genome, of, with, from, and"
9979,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.140350877,"the, sars-cov-2, and, of, virus, is, to, that"
9980,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.140350877,"this, in, the, of, that, sars-cov-2, to, virus"
9981,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.140350877,"the, of, sars-, cov-2, to, is, that, bats"
9982,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.140350877,"the, as, an, intermediate, host, a, from, to"
9983,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.140350877,"that, a, was, the, of, and, evidence, to"
9984,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.140350877,"serve, as, the, endemic, animal, reservoirs, viruses, and"
9985,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.140350877,"serve, as, the, endemic, animal, and, reservoirs, viruses"
9986,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.140350877,"the, and, bat, coronaviruses, that, in, are, to"
9987,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.140350877,"the, and, in, to, that, bat, coronaviruses, are"
9988,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.140350877,"in, two, related, genome, and, which, similar, to"
9989,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.140350877,"of, the, and, similar, to, sars-, cov-2, rbd"
9990,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.140350877,"cases, associated, with, the, huanan, market,, and, of, suggesting, a, team, that, were, covid-19, between, by"
9991,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.140350877,"the, a, from, an, intermediate, host, as, to"
9992,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.140350877,"by, a, team, of, the, that, covid-19, cases, were, between, and, associated, with, huanan, market,, suggesting"
9993,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.140350877,"that, sars-cov-2, through, contact, with, on, its, to"
9994,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.140350877,"that, of, sars-, cov-2, bats, to, is, the"
9995,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.140350877,"that, the, of, and, has, likely, been, from"
9996,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.140350877,"to, the, with, a, coronavirus, isolated, from, sars-cov-2"
9997,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.140350877,"a, is, the, to, that, in, virus, was"
9998,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.140350877,"bats, a, of, virus, by, the, china, found"
9999,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.140350877,"the, shows, that, at, of, complete, virus, to"
10000,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.140350877,"the, similarity, between, sars-cov-2, and, of, is, to"
10001,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.140350877,"in, two, related, and, which, similar, to, genome"
10002,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.140350877,"the, of, and, have, that, sars-cov-2, to, by"
10003,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.140350877,"the, has, been, of, that, likely, from, and"
10004,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.140350877,"complete, at, shows, that, the, virus, to, of"
10005,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.140350877,"the, rbd, to, suggesting, that, not, of, sars-cov-2,"
10006,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.140350877,"the, of, sars-cov-2, are, bats, and, be, to"
10007,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.140350877,"the, rbd, of, to, sars-cov-2,, suggesting, that, not"
10008,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.140350877,"the, of, and, similar, to, rbd, sars-, cov-2"
10009,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.14,"to, of, bats, and, more, sars-cov-2, than"
10010,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.14,"to, the, of, may, spillover, human, bat"
10011,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.14,"of, the, sars-cov-2, is, a, naturally, occurring"
10012,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.14,"recombination, between, and, in, the, of, sars-cov-2"
10013,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.14,"its, the, virus, was, from, a, in"
10014,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.14,"the, of, sars-cov-2, to, is, a, that"
10015,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.14,"that, a, of, to, ratg13,, the, sars-cov-2"
10016,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.14,"the, genome, sequence, of, to, bat, and"
10017,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.14,"the, is, of, known, with, and, in"
10018,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.14,"in, to, is, the, virus, and, was"
10019,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.14,"the, of, and, shown, that, by, evolutionary"
10020,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.14,"that, the, virus, and, to, intermediate, hosts"
10021,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.14,"the, sars-cov, of, shares, sequence, identity, with"
10022,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.14,"and, the, of, to, can, be, sars-cov-2"
10023,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.14,"this, found, in, the, of, sars-cov-2, to"
10024,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.14,"the, virus, it, not, that, been, a"
10025,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.14,"sars-cov-2, and, bat, coronaviruses, high, similarity, to"
10026,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.14,"studies, the, of, and, have, that, was"
10027,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.14,"the, was, from, at, and, of, wuhan"
10028,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.14,"the, that, sars-cov-2, with, at, of, and"
10029,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.14,"in, the, than, that, sars-cov-2, and, within"
10030,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.14,"the, as, a, it, genome, two, from"
10031,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.14,"no, evidence, at, all, that, the, of"
10032,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.14,"that, a, virus, with, to, and, the"
10033,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.14,"study, of, bats, a, in, with, the"
10034,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.14,"the, to, this, that, been, in, of"
10035,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.14,"is, and, that, sars-cov-2, to, intermediate, be"
10036,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.14,"a, virus, that, identity, with, the, bat"
10037,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.14,"the, to, covid-19, for, which, a, from"
10038,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.14,"that, the, of, recombination, a, to, genetic"
10039,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.14,"shown, that, and, the, of, by, evolutionary"
10040,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.14,"studies, and, that, have, the, was, of"
10041,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.14,"the, is, that, to, of, and, transmitted"
10042,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.14,"was, from, a, the, virus, its, in"
10043,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.14,"was, the, in, china, market, a, food"
10044,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.14,"was, in, a, and, are, to, the"
10045,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.14,"at, a, and, in, the, that, to"
10046,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.14,"is, the, to, in, virus, and, was"
10047,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.14,"and, the, covid-19, virus, has, to, of"
10048,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.14,"the, genetic, of, to, and, in, bats"
10049,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.14,"the, of, evidence, no, at, all, that"
10050,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.14,"in, the, virus, more, to, that, and"
10051,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.14,"the, sars-cov, and, that, in, similar, to"
10052,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.14,"the, of, shares, sequence, identity, with, sars-cov"
10053,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.14,"the, was, a, food, market, in, china"
10054,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.14,"after, only, of, could, be, the, that"
10055,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.14,"of, the, that, a, group, with, viruses"
10056,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.14,"the, has, been, of, over, to, bat"
10057,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.14,"the, that, sars-cov-2, to, a, also, and"
10058,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.14,"the, of, more, to, bat, genome, than"
10059,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.14,"the, to, sars-cov-2, of, bat, et, al.,"
10060,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.14,"of, 96.2%, similarity, to, genome, sequence, bat"
10061,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.14,"may, have, been, virus, to, and, the"
10062,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.14,"to, sars-cov-2, is, be, that, and, intermediate"
10063,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.14,"and, virus, with, the, covid-19, was, of"
10064,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.14,"of, the, covid-19, virus, and, was, with"
10065,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.14,"the, and, to, bat, of, genome, sequence"
10066,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.14,"to, of, the, covid-19, virus, has, and"
10067,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.14,"genome, revealed, a, sars-cov-2, and, the, from"
10068,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.14,"the, genome, revealed, sars-cov-2, and, from, a"
10069,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.14,"sars-cov-2, has, the, with, of, virus, and"
10070,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.14,"that, the, most, likely, hosts, for, a"
10071,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.14,"the, similar, to, and, sars-cov, that, in"
10072,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.14,"may, be, intermediate, hosts, to, pangolins, the"
10073,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.14,"from, bats, to, is, between, and, be"
10074,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.14,"the, of, and, that, is, transmitted, to"
10075,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.14,"of, be, the, after, that, only, could"
10076,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.14,"the, sars-cov-2, a, of, is, naturally, occurring"
10077,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.14,"the, sars-cov-2, of, et, al.,, to, bat"
10078,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.14,"the, as, a, of, from, and, r."
10079,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.14,"the, sars-cov-2, to, in, of, this, found"
10080,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.14,"of, to, sequence, which, was, found, in"
10081,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.14,"the, has, been, a, of, bat, and"
10082,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.14,"the, a, genome, as, it, two, from"
10083,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.14,"sars-cov-2, in, a, the, with, intermediate, for"
10084,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.14,"intermediate, for, sars-cov-2, pangolins, the, in, with"
10085,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.14,"to, the, of, may, bat, human, spillover"
10086,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.14,"of, the, bat, a, high, as, possible"
10087,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.14,"the, of, sars-cov-2, to, is, or, that"
10088,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.14,"not, a, that, the, virus, it, been"
10089,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.14,"the, within, sars-cov-2, than, that, in, and"
10090,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.14,"the, more, to, that, virus, in, and"
10091,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.14,"a, study, in, the, of, with, bats"
10092,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.14,"the, a, from, an, intermediate, host, to"
10093,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.14,"that, sars-, cov-2, the, of, and, sars-cov-2"
10094,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.14,"sars-cov-2, in, the, rbd,, six, key, rbd"
10095,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.14,"the, of, sars-cov-2, and, can, be, to"
10096,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.14,"a, intermediate, for, sars-cov-2, with, the, in"
10097,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.14,"to, be, the, hosts, pangolins, may, intermediate"
10098,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.14,"pangolins, intermediate, for, sars-cov-2, with, the, in"
10099,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.14,"sars-cov-2, is, humans, through, to, the, for"
10100,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.14,"from, to, an, intermediate, host, a, the"
10101,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.14,"of, covid-19, virus, that, it, is, the"
10102,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.14,"a, of, genetic, to, that, the, recombination"
10103,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.14,"in, can, that, the, recombination, of, bat"
10104,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.14,"are, and, the, was, to, a, in"
10105,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.14,"it, similar, to, the, coronaviruses,, and, was"
10106,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.14,"and, from, the, was, at, wuhan, of"
10107,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.14,"that, the, in, and, to, at, a"
10108,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.14,"with, the, known, and, is, in, of"
10109,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.14,"the, sars-cov-2, to, through, is, for, humans"
10110,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.14,"sars-cov-2, including, and, in, related, coronaviruses, that"
10111,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.14,"the, virus, a, identity, with, that, bat"
10112,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.14,"that, the, of, sars-cov-2, is, to, a"
10113,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.14,"is, that, the, of, to, sars-cov-2, or"
10114,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.14,"the, six, key, rbd, sars-cov-2, in, rbd,"
10115,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.14,"coronaviruses, that, related, sars-cov-2, in, including, and"
10116,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.14,"in, to, of, the, genetic, bats, and"
10117,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.14,"as, the, of, possible, a, high, bat"
10118,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.14,"intermediate, hosts, that, virus, to, and, the"
10119,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.14,"it, is, that, the, covid-19, of, virus"
10120,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.14,"it, was, coronaviruses,, and, similar, to, the"
10121,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.14,"this, of, to, the, in, that, been"
10122,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.14,"is, between, and, from, be, to, bats"
10123,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.14,"is, sars-cov-2, and, guangdong, the, viruses, in"
10124,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.14,"obtained, from, in, the, origin, of, and"
10125,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.14,"the, of, at, sars-cov-2, is, virus, in"
10126,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.14,"the, for, covid-19, a, which, to, from"
10127,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.14,"the, of, has, been, over, to, bat"
10128,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.14,"the, of, as, a, from, and, r."
10129,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.14,"the, of, a, and, has, been, bat"
10130,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.14,"of, has, been, that, the, a, lab"
10131,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.14,"a, of, the, has, been, lab, that"
10132,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.14,"that, the, and, this, has, been, from"
10133,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.14,"the, a, that, most, likely, hosts, for"
10134,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.14,"similarity, of, genome, sequence, 96.2%, to, bat"
10135,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.14,"found, in, of, sequence, which, was, to"
10136,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.14,"in, found, of, genome, sequences, which, to"
10137,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.14,"of, sequences, to, genome, which, found, in"
10138,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.14,"that, the, of, sars-cov-2, to, a, ratg13,"
10139,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.14,"the, virus, a, that, with, and, to"
10140,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.14,"the, virus, have, been, to, and, may"
10141,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.14,"a, group, of, the, with, viruses, that"
10142,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.14,"viruses, the, results, in, figs., and, that"
10143,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.14,"results, the, in, figs., and, that, viruses"
10144,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.14,"the, in, that, bats, are, hosts, for"
10145,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.14,"that, genome, are, to, and, on, the"
10146,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.14,"the, that, has, been, from, and, this"
10147,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.14,"viruses, the, sars-cov-2, in, is, guangdong, and"
10148,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.14,"to, this, that, sars-cov-2, similarity, the, we"
10149,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.14,"are, the, in, that, bats, hosts, for"
10150,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.14,"and, sars-cov-2, to, bats, of, more, than"
10151,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.14,"of, the, sars-, cov-2, that, and, sars-cov-2"
10152,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.14,"of, the, in, obtained, from, origin, and"
10153,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.14,"are, to, on, the, genome, and, that"
10154,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.14,"the, genome, of, more, than, to, bat"
10155,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.14,"the, between, sars-cov-2, and, of, in, recombination"
10156,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.14,"the, of, with, and, that, sars-cov-2, at"
10157,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.14,"that, the, of, bat, in, recombination, can"
10158,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.14,"this, we, similarity, sars-cov-2, to, the, that"
10159,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.14,"virus, in, is, at, sars-cov-2, the, of"
10160,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.14,"sars-cov-2, to, high, similarity, and, coronaviruses, bat"
10161,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.139784946,"the, of, have, a, meat,, to, live, in, wild, market, were, virus, was"
10162,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.139784946,"in, a, of, to, have, the, virus, was, wild, were, live, market, meat,"
10163,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.139534884,"this, natural, and, the, virus, of"
10164,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.139534884,"the, of, be, to, and, animal"
10165,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.139534884,"the, virus, from, to, with, human"
10166,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.139534884,"from, the, been, to, have, sars-cov-2"
10167,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.139534884,"is, that, had, sars-cov-2, a, in"
10168,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.139534884,"sars-cov-2, is, a, virus, that, with"
10169,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.139534884,"and, that, the, to, of, bat"
10170,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.139534884,"that, the, of, viruses, to, coronaviruses"
10171,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.139534884,"the, of, covid-, 19, to, and"
10172,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.139534884,"bat, to, as, sars-cov-2, the, genome"
10173,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.139534884,"the, that, a, genome, it, to"
10174,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.139534884,"the, is, to, identical, that, of"
10175,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.139534884,"the, is, of, sars-cov-2, to, a"
10176,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.139534884,"sars-cov-2, is, to, the, bat, cov"
10177,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.139534884,"the, of, that, sars-cov-2, is, a"
10178,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.139534884,"that, bat, virus, genome, 96.2%, sars-cov-2"
10179,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.139534884,"the, sequence, that, and, sars-cov-2, same"
10180,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.139534884,"the, of, in, to, with, and"
10181,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.139534884,"in, the, of, is, to, sars-cov-2"
10182,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.139534884,"the, of, that, a, has, in"
10183,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.139534884,"the, viruses, zoonotic, reservoirs, and, of"
10184,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.139534884,"have, bats, are, the, of, and"
10185,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.139534884,"the, sequence, virus, and, closest, was"
10186,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.139534884,"the, is, to, a, virus, in"
10187,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.139534884,"a, and, in, the, that, to"
10188,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.139534884,"96.2%, sequence, that, and, human, a"
10189,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.139534884,"the, that, is, a, virus, in"
10190,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.139534884,"the, animal, market, likely, that, in"
10191,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.139534884,"the, of, covid-19, to, that, zoonotic"
10192,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.139534884,"the, that, has, evolutionary, of, and"
10193,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.139534884,"can, cause, to, and, intermediate, hosts"
10194,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.139534884,"virus, from, animals, to, for, the"
10195,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.139534884,"sars-cov-2, the, in, that, of, is"
10196,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.139534884,"bat, is, the, with, sars-cov-2, that"
10197,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.139534884,"are, to, the, and, bats, be"
10198,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.139534884,"the, of, has, yet, been, is"
10199,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.139534884,"transmitted, from, an, animal, to, a"
10200,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.139534884,"studies, nucleotide, and, that, have, the"
10201,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.139534884,"has, throughout, genome, that, and, sars-cov-2"
10202,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.139534884,"studies, that, nucleotide, have, and, the"
10203,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.139534884,"the, was, coronavirus, that, bat, and"
10204,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.139534884,"that, the, wuhan, institute, of, virology"
10205,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.139534884,"the, phylogenetic, that, at, of, and"
10206,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.139534884,"the, of, that, was, not, from"
10207,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.139534884,"related, sars-cov-2, bats, and, pangolins, from"
10208,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.139534884,"the, to, of, sars-cov-2, bat, least"
10209,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.139534884,"a, bat, of, sars-cov-2, at, the"
10210,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.139534884,"that, sars-cov-2, the, at, of, to"
10211,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.139534884,"through, that, the, be, and, sars-cov-2"
10212,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.139534884,"cases, to, the, market, in, that"
10213,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.139534884,"two, closely, related, to, a, the"
10214,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.139534884,"animal, hosts, and, the, of, respiratory"
10215,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.139534884,"the, that, animal, market, in, likely"
10216,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.139534884,"the, of, a, zoonotic, and, in"
10217,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.139534884,"and, to, the, zoonotic, source, of"
10218,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.139534884,"is, that, sars-cov-2, a, had, in"
10219,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.139534884,"that, the, genome, to, a, it"
10220,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.139534884,"the, to, ,, it, that, as"
10221,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.139534884,"that, from, a, to, it, in"
10222,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.139534884,"is, considerable, to, that, originated, in"
10223,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.139534884,"to, the, respiratory, syndrome, have, in, of, that, animals, a, role, emergence"
10224,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.139534884,"and, that, the, bat, coronavirus, was"
10225,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.139534884,"has, with, bat, that, and, a"
10226,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.139534884,"the, that, to, a, with, bat"
10227,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.139534884,"that, can, in, animals, which, different"
10228,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.139534884,"that, the, to, a, high, and"
10229,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.139534884,"and, bat, compared, to, the, that"
10230,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.139534884,"with, the, and, to, in, of"
10231,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.139534884,"the, to, and, that, a, high"
10232,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.139534884,"a, of, the, with, that, and"
10233,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.139534884,"a, of, in, and, to, the"
10234,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.139534884,"in, that, the, cases, to, market"
10235,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.139534884,"that, the, of, is, identical, to"
10236,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.139534884,"is, the, to, that, virus, and"
10237,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.139534884,"the, virus, from, an, to, and"
10238,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.139534884,"the, to, is, that, bats, as"
10239,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.139534884,"that, sars-cov-2, from, a, to, intermediate"
10240,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.139534884,"the, that, sars-cov-2, virus, and, to"
10241,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.139534884,"the, virus, from, to, identity, with"
10242,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.139534884,"sars-cov-2, the, have, been, to, from"
10243,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.139534884,"to, the, of, sars-cov-2, from, humans"
10244,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.139534884,"sars-cov-2, similar, to, and, the, of"
10245,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.139534884,"that, the, of, to, a, and"
10246,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.139534884,"sars-cov-2, a, virus, that, to, the"
10247,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.139534884,"sars-cov-2, and, to, the, that, originated"
10248,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.139534884,"to, the, of, and, bat, human"
10249,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.139534884,"the, of, to, pangolin, and, bat"
10250,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.139534884,"the, of, sars-cov-2, and, an, animal"
10251,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.139534884,"the, to, was, in, from, a"
10252,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.139534884,"the, are, bats, in, and, china"
10253,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.139534884,"bats, and, the, from, in, china"
10254,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.139534884,"that, the, virus, and, bats, to"
10255,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.139534884,"the, of, that, to, zoonotic, covid-19"
10256,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.139534884,"the, virus, is, to, and, in"
10257,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.139534884,"in, to, is, the, virus, and"
10258,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.139534884,"that, virus, similar, to, and, the"
10259,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.139534884,"the, outbreak, seafood, in, wuhan,, and"
10260,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.139534884,"the, of, and, that, is, to"
10261,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.139534884,"that, the, virus, bats, and, to"
10262,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.139534884,"is, and, that, of, to, be"
10263,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.139534884,"is, possible, that, sars-cov-2, the, genomic"
10264,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.139534884,"genome, has, sars-cov-2, the, of, bat"
10265,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.139534884,"been, to, the, of, sars-cov-2, has"
10266,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.139534884,"a, host, for, sars-cov-2, it, the"
10267,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.139534884,"study, bat, be, the, of, animal"
10268,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.139534884,"can, intermediate, hosts, cause, to, and"
10269,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.139534884,"the, isolated, in, from, of, a"
10270,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.139534884,"bats, most, likely, of, bat, and"
10271,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.139534884,"of, most, by, genetic, is, bat"
10272,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.139534884,"animals, from, virus, to, for, the"
10273,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.139534884,"the, in, related, coronaviruses, of, is"
10274,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.139534884,"the, virus, an, to, and, from"
10275,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.139534884,"is, that, and, be, of, to"
10276,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.139534884,"the, closest, sequence, virus, and, was"
10277,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.139534884,"virus, and, genome, was, available, the"
10278,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.139534884,"virus, sequence, identity, with, the, bat"
10279,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.139534884,"the, sequence, of, showed, identity, and"
10280,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.139534884,"with, the, of, bats, genome, from"
10281,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.139534884,"a, that, the, laboratory, and, sars-cov-2"
10282,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.139534884,"and, the, that, by, a, natural"
10283,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.139534884,"seafood, in, wuhan,, the, outbreak, and"
10284,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.139534884,"that, and, in, a, seafood, market"
10285,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.139534884,"in, from, to, and, the, humans"
10286,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.139534884,"a, that, the, to, and, in"
10287,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.139534884,"the, in, from, market, that, outbreak"
10288,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.139534884,"studies, that, to, and, a, the"
10289,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.139534884,"and, respiratory, the, of, animal, hosts"
10290,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.139534884,"that, a, seafood, market, in, and"
10291,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.139534884,"was, in, and, on, that, a"
10292,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.139534884,"the, genome, of, sars-cov-2, has, bat"
10293,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.139534884,"between, and, in, the, of, sars-cov-2"
10294,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.139534884,"that, the, of, with, a, and"
10295,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.139534884,"the, of, to, it, is, that"
10296,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.139534884,"the, of, to, that, transmitted, humans."
10297,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.139534884,"that, the, to, seafood, market,, of"
10298,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.139534884,"the, was, from, to, a, in"
10299,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.139534884,"of, the, in, isolated, from, a"
10300,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.139534884,"a, of, bat, from, in, sars-cov-2"
10301,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.139534884,"ratg13,, was, in, yunnan, the, closest"
10302,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.139534884,"that, was, and, in, a, on"
10303,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.139534884,"a, that, the, was, and, in"
10304,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.139534884,"the, of, in, taken, that, was"
10305,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.139534884,"of, a, that, the, many, and"
10306,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.139534884,"of, the, in, and, that, a"
10307,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.139534884,"in, the, of, for, has, been"
10308,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.139534884,"and, the, of, sars-cov-2, natural, origin"
10309,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.139534884,"origin, the, ratg13, from, between, and"
10310,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.139534884,"the, in, a, zoonotic, of, and"
10311,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.139534884,"been, and, in, the, of, has"
10312,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.139534884,"the, reservoirs, of, and, zoonotic, viruses"
10313,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.139534884,"sars-cov-2, and, to, the, viruses, in"
10314,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.139534884,"from, with, genome, bats, the, of"
10315,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.139534884,"a, it, the, sars-cov-2, for, host"
10316,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.139534884,"the, viruses, of, coronaviruses, that, to"
10317,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.139534884,"the, genome, virus, and, available, was"
10318,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.139534884,"the, sars-cov-2, to, is, that, not"
10319,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.139534884,"the, coronaviruses, sars-cov-2, in, and, cambodia"
10320,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.139534884,"of, which, from, shared, with, sars-cov-2"
10321,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.139534884,"identity, with, the, sars-cov-2, in, collected"
10322,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.139534884,"virus, genome, bat, 96.2%, that, sars-cov-2"
10323,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.139534884,"that, sars-cov-2, has, similarity, virus, of"
10324,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.139534884,"to, with, the, from, virus, human"
10325,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.139534884,"the, virus, to, identity, with, from"
10326,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.139534884,"the, has, been, of, is, yet"
10327,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.139534884,"the, and, sequence, that, sars-cov-2, same"
10328,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.139534884,"the, from, in, to, humans, and"
10329,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.139534884,"the, of, sars-cov-2, and, from, bats"
10330,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.139534884,"sars-cov-2, has, the, with, at, of"
10331,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.139534884,"the, that, sars-cov-2, and, a, laboratory"
10332,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.139534884,"the, also, to, sars-cov-2, by, of"
10333,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.139534884,"it, is, the, for, sars-cov-2, to"
10334,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.139534884,"of, that, to, the, and, was"
10335,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.139534884,"that, the, outbreak, from, market, in"
10336,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.139534884,"the, was, in, that, taken, of"
10337,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.139534884,"of, sequences, at, the, outbreak, in"
10338,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.139534884,"a, is, the, to, in, virus"
10339,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.139534884,"the, to, closely, related, sars-cov-2, in"
10340,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.139534884,"the, related, to, covid-19, a, is"
10341,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.139534884,"are, and, the, bats, in, china"
10342,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.139534884,"least, to, bat, the, of, sars-cov-2"
10343,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.139534884,"and, most, likely, bats, of, bat"
10344,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.139534884,"the, coronaviruses, and, in, cambodia, sars-cov-2"
10345,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.139534884,"the, sars-cov-2, to, closely, related, in"
10346,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.139534884,"are, and, in, the, that, to"
10347,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.139534884,"the, that, sars-cov-2, are, to, bat"
10348,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.139534884,"the, viruses, in, to, sars, and, progenitor, were, virus, for, southern, china"
10349,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.139534884,"viruses, to, the, in, and, for"
10350,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.139534884,"of, from, which, shared, with, sars-cov-2"
10351,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.139534884,"sars-cov-2, to, genome, bat, as, the"
10352,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.139534884,"at, which, the, closest, sars-cov-2,, genome"
10353,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.139534884,"the, of, sars-cov-2, to, also, by"
10354,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.139534884,"to, sars-cov-2, similarity, when, the, of"
10355,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.139534884,"to, in, human, intestinal, experiments, conducted"
10356,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.139534884,"a, related, the, two, closely, to"
10357,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.139534884,"a, viruses, and, to, which, the"
10358,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.139534884,"experiments, conducted, to, in, human, intestinal"
10359,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.139534884,"genetic, is, most, by, of, bat"
10360,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.139534884,"genetic, of, the, virus, is, most"
10361,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.139534884,"is, the, bat, to, sars-cov-2,, of"
10362,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.139534884,"through, the, that, be, sars-cov-2, and"
10363,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.139534884,"in, it, be, that, the, and"
10364,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.139534884,"the, progenitor, virus, for, sars, and, viruses, to, were, in, southern, china"
10365,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.139534884,"the, to, that, are, in, and"
10366,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.139534884,"sars-cov-2, with, is, a, virus, that"
10367,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.139534884,"a, to, that, sars-cov-2, the, virus"
10368,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.139534884,"sars-cov-2, and, related, from, bats, pangolins"
10369,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.139534884,"the, of, in, to, a, and"
10370,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.139534884,"viruses, to, and, a, the, which"
10371,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.139534884,"in, the, of, to, new, which"
10372,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.139534884,"the, sequence, virus, with, bat, identity"
10373,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.139534884,"the, collected, in, identity, with, sars-cov-2"
10374,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.139534884,"the, that, sars-cov-2, a, with, bat"
10375,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.139534884,"the, that, sars-cov-2, a, virus, in"
10376,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.139534884,"sars-cov-2, is, a, or, that, not"
10377,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.139534884,"the, that, is, not, to, sars-cov-2"
10378,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.139534884,"that, sars-cov-2, is, not, a, or"
10379,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.139534884,"this, that, the, likely, of, sars-cov-2"
10380,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.139534884,"of, it, is, that, sars-cov-2, a"
10381,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.139534884,"it, is, that, sars-cov-2, a, of"
10382,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.139534884,",, the, that, as, it, to"
10383,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.139534884,"to, is, that, bats, the, as"
10384,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.139534884,"the, is, that, to, of, it"
10385,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.139534884,"the, of, that, likely, to, bat"
10386,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.139534884,"the, reservoir, is, it, to, of"
10387,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.139534884,"the, by, that, natural, and, a"
10388,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.139534884,"shows, that, the, evolutionary, of, and"
10389,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.139534884,"genomic, that, sars-cov-2, is, the, possible"
10390,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.139534884,"that, the, virus, in, to, of"
10391,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.139534884,"that, sars-cov-2, the, of, virus, to"
10392,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.139534884,"the, of, sars-cov-2, with, and, identical"
10393,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.139534884,"the, of, in, is, related, coronaviruses"
10394,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.139534884,"the, and, covid-, 19, of, to"
10395,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.139534884,"of, the, sequence, and, showed, identity"
10396,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.139534884,"the, and, of, to, covid-, 19"
10397,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.139534884,"the, of, more, to, cov, than"
10398,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.139534884,"of, to, the, seafood, market,, that"
10399,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.139534884,"the, in, of, to, that, virus"
10400,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.139534884,"that, the, of, was, and, to"
10401,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.139534884,"that, the, role, of, in, emergence, to, respiratory, syndrome, animals, have, a"
10402,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.139534884,"that, in, different, which, can, animals"
10403,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.139534884,"of, has, not, been, that, the"
10404,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.139534884,"the, sars-cov-2, their, and, origin, of"
10405,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.139534884,"and, the, from, bats, in, china"
10406,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.139534884,"the, covid-19, is, to, a, related"
10407,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.139534884,"a, that, 96.2%, sequence, human, and"
10408,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.139534884,"that, sars-cov-2, has, and, throughout, genome"
10409,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.139534884,"a, that, has, with, bat, and"
10410,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.139534884,"the, zoonotic, to, source, of, and"
10411,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.139534884,"that, in, a, it, to, from"
10412,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.139534884,"to, sars-cov-2, a, that, from, intermediate"
10413,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.139534884,"show, that, sars-cov-2, to, a, bat"
10414,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.139534884,"the, not, that, has, been, of"
10415,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.139534884,"that, sars-cov-2, has, the, but, of"
10416,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.139534884,"the, of, most, virus, genetic, is"
10417,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.139534884,"they, that, is, the, of, sars-cov-2"
10418,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.139534884,"the, natural, origin, of, sars-cov-2, and"
10419,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.139534884,"evidence, and, in, the, of, sars-cov-2"
10420,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.139534884,"to, ratg13, has, an, and, be"
10421,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.139534884,"the, origin, between, from, and, ratg13"
10422,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.139534884,"has, an, to, ratg13, and, be"
10423,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.139534884,"the, sars-cov-2, to, it, is, for"
10424,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.139534884,"the, many, and, that, a, of"
10425,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.139534884,"a, at, bat, the, of, sars-cov-2"
10426,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.139534884,"the, of, sequences, in, at, outbreak"
10427,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.139534884,"of, the, in, sars-cov-2, sequences, a"
10428,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.139534884,"the, virus, similar, to, and, that"
10429,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.139534884,"the, in, and, that, a, of"
10430,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.139534884,"a, of, sars-cov-2, sequences, the, in"
10431,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.139534884,"that, the, of, sars-cov-2, and, viruses"
10432,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.139534884,"that, sars-cov-2, the, with, of, and"
10433,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.139534884,"the, are, bats, and, be, to"
10434,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.139534884,"the, sars-cov-2, with, that, is, bat"
10435,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.139534884,"the, sars-cov-2, cluster, this, probable, bat"
10436,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.139534884,"from, of, bats, sars-cov-2, and, the"
10437,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.139534884,"of, the, and, that, sars-cov-2, viruses"
10438,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.139534884,"that, is, considerable, originated, in, to"
10439,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.139534884,"compared, the, to, bat, and, that"
10440,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.139534884,"to, that, sars-cov-2, originated, the, and"
10441,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.139534884,"sars-cov-2, to, the, viruses, in, and"
10442,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.139534884,"the, sars-cov-2, is, to, bat, cov"
10443,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.139534884,"the, of, sars-cov-2, likely, that, this"
10444,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.139534884,"of, the, sars-cov-2, their, origin, and"
10445,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.139534884,"this, bat, the, cluster, sars-cov-2, probable"
10446,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.139534884,"in, the, between, and, of, bat"
10447,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.139534884,"similar, to, and, the, of, sars-cov-2"
10448,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.139534884,"the, a, that, with, bat, to"
10449,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.139534884,"a, that, with, the, sars-cov-2, bat"
10450,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.139534884,"the, of, to, bat, likely, that"
10451,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.139534884,"the, of, more, than, to, cov"
10452,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.139534884,"show, that, sars-cov-2, a, bat, to"
10453,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.139534884,"the, that, sars-cov-2, with, of, to"
10454,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.139534884,"sars-cov-2, and, sars-cov, with, the, of"
10455,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.139534884,"and, to, the, of, sars-cov-2, is"
10456,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.139534884,"between, sars-cov-2, and, the, of, in"
10457,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.139534884,"and, in, the, evidence, of, sars-cov-2"
10458,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.139534884,"bats, are, the, have, of, and"
10459,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.139534884,"and, of, this, natural, the, virus"
10460,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.139534884,"has, that, and, the, of, evolutionary"
10461,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.139534884,"phylogenetic, and, that, the, at, of"
10462,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.139534884,"to, sars-cov-2, virus, that, and, the"
10463,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.139534884,"the, of, that, sars-cov-2, to, with"
10464,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.139534884,"in, it, that, the, be, and"
10465,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.139534884,"in, the, bat, of, between, and"
10466,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.139534884,"that, not, from, the, was, of"
10467,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.139534884,"the, that, to, of, transmitted, humans."
10468,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.139534884,"of, in, to, which, the, new"
10469,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.139534884,"that, virus, has, similarity, of, sars-cov-2"
10470,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.139534884,"the, to, sars-cov-2, when, similarity, of"
10471,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.139534884,"of, sars-cov-2, has, but, that, the"
10472,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.139534884,"the, that, of, sars-cov-2, is, they"
10473,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.139534884,"the, of, and, sars-cov-2, an, animal"
10474,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.139534884,"the, of, bat, animal, be, study"
10475,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.139534884,"in, the, of, that, has, a"
10476,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.139534884,"a, is, the, that, in, virus"
10477,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.139534884,"a, virus, that, the, sars-cov-2, in"
10478,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.139534884,"the, of, to, it, is, reservoir"
10479,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.139534884,"sars-cov-2, in, from, of, a, bat"
10480,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.139534884,"ratg13,, the, closest, was, in, yunnan"
10481,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.139534884,"closest, sars-cov-2,, which, at, the, genome"
10482,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.139534884,"the, of, to, sars-cov-2,, is, bat"
10483,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.139534884,"sars-cov-2, and, some, coronaviruses, high, of"
10484,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.139534884,"some, sars-cov-2, and, of, coronaviruses, high"
10485,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.139240506,"intermediate, as, and, for, the, of, that, sars-cov-2, may, in, a"
10486,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.139240506,"the, as, a, of, that, from, to, humans, civets, infected, and"
10487,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.139240506,"the, of, civets, as, a, that, from, infected, humans, to, and"
10488,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.139240506,"sars-cov-2, may, in, a, of, and, that, the, as, intermediate, for"
10489,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.139130435,"in, a, of, to, the, samples, from, and, sars, at, were, more, closely, related, than, virus"
10490,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.139130435,"in, the, of, sars, a, at, virus, samples, from, were, to, and, more, closely, related, than"
10491,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.138888889,"a, of, in, bats, horseshoe"
10492,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.138888889,"coronaviruses, are, viruses, in, a"
10493,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.138888889,"pangolin, to, bat, and, human"
10494,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.138888889,"are, coronaviruses, in, a, viruses"
10495,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.138888889,"viruses, are, of, coronaviruses, distributed"
10496,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.138888889,"the, en-, sars, viruses,, are"
10497,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.138888889,"are, and, the, bats, to"
10498,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.138888889,"and, bat, coronaviruses, many, to"
10499,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.138888889,"sars-cov-2, to, in, and, of"
10500,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.138888889,"of, in, and, to, which"
10501,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.138888889,"of, sars-cov-2, to, which, in"
10502,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.138888889,"the, sars, viruses,, are, en-"
10503,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.138888889,"are, the, very, similar, to"
10504,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.138888889,"to, is, sars-cov-2, whole, genome"
10505,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.138888889,"that, a, virus, with, sars-cov-2"
10506,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.138888889,"coronaviruses, are, viruses, distributed, of"
10507,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.138888889,"many, bat, coronaviruses, to, and"
10508,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.138888889,"genome, bat, as, natural, host"
10509,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.138888889,"the, that, sars-cov-2, highly, to"
10510,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.138888889,"the, with, genome, that, to"
10511,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.138888889,"have, that, the, with, to"
10512,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.138888889,"found, the, of, to, sars-cov-2"
10513,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.138888889,"that, sars-cov-2, the, bat, cov"
10514,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.138888889,"host, of, has, been, origin"
10515,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.138888889,"evolutionary, of, virus, bat, and"
10516,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.138888889,"the, sars-cov-2, in, closer, with"
10517,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.138888889,"is, the, sars-cov-2, to, bat"
10518,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.138888889,"that, the, as, of, a"
10519,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.138888889,"the, of, are, and, other"
10520,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.138888889,"is, to, a, and, the"
10521,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.138888889,"a, that, the, is, and"
10522,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.138888889,"the, as, of, intermediate, malayan"
10523,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.138888889,"the, intermediate, to, of, as"
10524,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.138888889,"to, humans, spillover, intermediate, hosts"
10525,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.138888889,"the, of, sars-cov-2, as, from"
10526,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.138888889,"a, is, the, to, and"
10527,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.138888889,"the, a, coronavirus, and, to"
10528,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.138888889,"the, an, animal, to, and"
10529,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.138888889,"the, palm, civets, as, intermediate, that, virus, from, to, and"
10530,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.138888889,"the, a, coronavirus, with, to"
10531,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.138888889,"to, from, a, with, sars-cov-2"
10532,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.138888889,"a, sequence, with, the, sars-cov-2"
10533,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.138888889,"the, to, a, from, is"
10534,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.138888889,"and, the, of, which, respiratory"
10535,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.138888889,"of, and, to, which, the"
10536,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.138888889,"and, coronaviruses, to, the, of"
10537,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.138888889,"the, in, of, that, sars-cov-2"
10538,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.138888889,"of, analysis, that, the, bat"
10539,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.138888889,"of, the, in, that, sars-cov-2"
10540,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.138888889,"that, the, sars-cov-2, bat, is"
10541,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.138888889,"is, the, bat, in, of"
10542,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.138888889,"of, sars-cov-2, and, sars-cov, bat"
10543,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.138888889,"that, the, of, sars-cov, and"
10544,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.138888889,"that, the, and, of, bat"
10545,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.138888889,"sars-cov-2, to, bats, be, the"
10546,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.138888889,"the, of, sars-cov-2, and, bats"
10547,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.138888889,"sars-cov-2, the, of, and, to"
10548,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.138888889,"has, been, sars-cov-2, in, humans"
10549,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.138888889,"sars-cov-2, is, to, be, from"
10550,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.138888889,"that, the, a, in, and"
10551,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.138888889,"that, the, originated, in, and"
10552,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.138888889,"a, origin, by, the, in"
10553,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.138888889,"sars-cov-2, a, natural, origin, humans"
10554,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.138888889,"that, sars-cov-2, has, natural, and"
10555,hese close genetic relations suggest that they all have their ecological origin in bat populations,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.138888889,"suggest, that, they, have, bat"
10556,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.138888889,"of, closely, related, from, bats"
10557,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.138888889,"of, sars-cov-2, from, pangolins, and"
10558,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.138888889,"the, of, sars-cov-2, a, from"
10559,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.138888889,"of, the, that, and, sars-cov-2"
10560,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.138888889,"that, are, the, sars-cov-2, to"
10561,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.138888889,"the, are, closely, related, to"
10562,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.138888889,"the, two, huanan, market, in"
10563,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.138888889,"that, are, the, to, a"
10564,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.138888889,"the, of, with, and, is"
10565,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.138888889,"the, and, this, origin, of"
10566,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.138888889,"this, in, and, the, of"
10567,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.138888889,"taken, from, the, huanan, virus"
10568,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.138888889,"a, the, was, of, at"
10569,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.138888889,"was, et, the, lineage, of"
10570,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.138888889,"in, the, that, was, at"
10571,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.138888889,"at, the, huanan, market, in"
10572,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.138888889,"in, was, that, sars-cov-2, the"
10573,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.138888889,"this, found, in, the, analysis, of, that, was, to, virus"
10574,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.138888889,"that, has, the, with, bat"
10575,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.138888889,"virus, the, huanan, from, taken"
10576,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.138888889,"the, from, that, and, animals"
10577,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.138888889,"virus, that, is, the, and"
10578,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.138888889,"coronaviruses, zoonotic, to, that, and"
10579,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.138888889,"the, of, in, host, was"
10580,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.138888889,"that, a, bat, genome, 96.2%"
10581,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.138888889,"to, the, of, as, intermediate"
10582,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.138888889,"the, of, intermediate, host, was"
10583,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.138888889,"of, the, commonly, known, as"
10584,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.138888889,"the, pandemic, of, a, in"
10585,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.138888889,"the, bats, is, and, available"
10586,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.138888889,"to, from, with, the, sars-cov-2"
10587,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.138888889,"to, the, from, a, with"
10588,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.138888889,"from, the, to, with, sars-cov-2"
10589,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.138888889,"from, to, humans, and, the"
10590,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.138888889,"the, to, sars-cov-2, by, of"
10591,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.138888889,"that, the, sars-cov-2, to, a"
10592,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.138888889,"human, and, to, bat, pangolin"
10593,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.138888889,"is, to, the, bat, pangolin"
10594,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.138888889,"the, of, to, bat, pangolin"
10595,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.138888889,"the, is, and, to, of"
10596,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.138888889,"bats, and, are, to, the"
10597,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.138888889,"from, to, are, bats, the"
10598,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.138888889,"a, in, the, was, to"
10599,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.138888889,"was, and, to, bats, the"
10600,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.138888889,"to, the, most, of, may"
10601,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.138888889,"to, that, has, been, in"
10602,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.138888889,"the, of, that, as, a"
10603,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.138888889,"the, of, is, that, as"
10604,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.138888889,"the, that, at, of, virus"
10605,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.138888889,"the, is, to, virus, in"
10606,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.138888889,"the, and, is, origin, to"
10607,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.138888889,"the, virus, to, and, may"
10608,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.138888889,"is, that, the, of, to"
10609,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.138888889,"virus, sequence, that, identity, the"
10610,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.138888889,"the, sars-cov-2, bats, be, to"
10611,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.138888889,"bats, to, is, be, the"
10612,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.138888889,"to, bat, the, of, sars-cov-2"
10613,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.138888889,"of, reported, to, sars-cov-2, the"
10614,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.138888889,"sars-cov-2, genome, to, the, of"
10615,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.138888889,"the, bat, coronavirus, to, of"
10616,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.138888889,"ace2, receptor, a, sars-cov-2, and"
10617,"According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.138888889,"to, sars-cov, is, sars-like, bat"
10618,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.138888889,"is, to, sars-like, bat, sars-cov"
10619,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.138888889,"to, intermediate, hosts, spillover, humans"
10620,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.138888889,"in, to, and, infection, humans"
10621,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.138888889,"is, a, virus, that, to"
10622,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.138888889,"are, the, from, bats, to"
10623,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.138888889,"to, the, of, from, bats"
10624,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.138888889,"the, of, in, from, outbreak"
10625,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.138888889,"the, in, of, to, also"
10626,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.138888889,"is, the, to, in, of"
10627,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.138888889,"to, an, animal, and, the"
10628,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.138888889,"the, virus, and, may, to"
10629,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.138888889,"is, that, sars-cov-2, jumped, the"
10630,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.138888889,"the, that, sars-cov-2, jumped, t"
10631,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.138888889,"that, the, sars-cov-2, and, is"
10632,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.138888889,"that, the, of, had, to"
10633,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.138888889,"the, covid-19, virus, to, of"
10634,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.138888889,"to, virus, genome, available, the"
10635,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.138888889,"to, of, appear, from, with"
10636,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.138888889,"the, of, to, bats, reservoir"
10637,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.138888889,"the, with, of, virus, to"
10638,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.138888889,"coronaviruses, zoonotic, that, to, and"
10639,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.138888889,"the, that, to, includes, and"
10640,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.138888889,"of, sars-, bats, to, intermediate, a, coronavirus, pangolin, with, the"
10641,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.138888889,"that, sars-cov-2, to, highly, the"
10642,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.138888889,"analysis, that, the, of, coronavirus"
10643,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.138888889,"results, that, the, sars-cov-2, genomic"
10644,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.138888889,"the, of, has, human, and"
10645,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.138888889,"that, the, covid-19, of, and"
10646,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.138888889,"two, s, the, coronavirus,, and"
10647,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.138888889,"the, transmitted, to, animals, a"
10648,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.138888889,"in, the, a, and, market"
10649,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.138888889,"the, which, of, and, respiratory"
10650,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.138888889,"the, of, and, are, is"
10651,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.138888889,"in, is, sars-cov-2, that, virus"
10652,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.138888889,"are, the, of, and, other"
10653,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.138888889,"may, the, of, to, most"
10654,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.138888889,"bats, pangolins, be, the, hosts"
10655,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.138888889,"that, sars-cov-2, part, of, the"
10656,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.138888889,"as, and, to, et, al.,, can, be, that, sars-cov-2, is"
10657,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.138888889,"a, coronavirus, strain, the, with"
10658,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.138888889,"that, to, with, genome, the"
10659,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.138888889,"of, a, at, the, was"
10660,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.138888889,"the, at, was, that, in"
10661,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.138888889,"the, was, to, a, in"
10662,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.138888889,"a, the, coronavirus, strain, with"
10663,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.138888889,"the, of, to, sars-, cov-2"
10664,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.138888889,"a, that, the, of, sars-cov-2"
10665,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.138888889,"that, a, of, the, is"
10666,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.138888889,"of, a, analysis, that, the"
10667,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.138888889,"the, at, huanan, market, in"
10668,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.138888889,"of, lineage, the, was, et"
10669,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.138888889,"and, the, was, bats, to"
10670,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.138888889,"of, to, the, and, was"
10671,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.138888889,"was, rhinolophus, bat, in, yunnan"
10672,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.138888889,"related, sars-cov-2, in, rhinolophus, bats"
10673,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.138888889,"animal, at, the, spillover, that"
10674,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.138888889,"that, the, of, origin, be"
10675,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.138888889,"the, of, at, that, animal"
10676,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.138888889,"a, sars-cov-2, ace2, receptor, and"
10677,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.138888889,"the, was, in, that, for"
10678,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.138888889,"the, has, been, in, of"
10679,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.138888889,"the, of, sars-cov-2, from, as"
10680,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.138888889,"of, sars-cov-2, and, from, pangolins"
10681,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.138888889,"a, the, of, sars-cov-2, from"
10682,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.138888889,"from, of, sars-cov-2, and, the"
10683,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.138888889,"r., a, of, sars-cov-2, the"
10684,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.138888889,"of, the, and, sars-cov-2, a"
10685,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.138888889,"the, between, sars-cov-2, and, ratg13"
10686,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.138888889,"in, of, to, the, virus, that, was, this, analysis, found"
10687,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.138888889,"the, of, closely, related, in, found, virus, similar, to, that"
10688,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.138888889,"the, a, animals, transmitted, to"
10689,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.138888889,"of, a, the, bat, and"
10690,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.138888889,"and, sars-cov-2, in, to, of"
10691,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.138888889,"the, viruses, to, sars-cov-2, of"
10692,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.138888889,"in, and, the, for, of"
10693,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.138888889,"sars-cov-2, is, to, of, the"
10694,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.138888889,"that, the, had, of, to"
10695,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.138888889,"that, the, covid-19, is, of"
10696,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.138888889,"the, virus, had, and, to"
10697,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.138888889,"available, genome, to, the, virus"
10698,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.138888889,"sars-cov-2, is, to, in, the"
10699,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.138888889,"in, 2, and, sars-cov-2, with, this, that, the, is, than"
10700,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.138888889,"a, sars-, to, the, coronavirus, bats, of, with, pangolin, intermediate"
10701,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.138888889,"the, from, nucleotide, identity, with"
10702,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.138888889,"sars-cov-2, with, a, virus, that"
10703,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.138888889,"genome, bat, that, 96.2%, a"
10704,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.138888889,"the, nucleotide, from, identity, with"
10705,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.138888889,"has, been, host, of, origin"
10706,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.138888889,"the, sequence, of, that, same"
10707,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.138888889,"found, the, of, sars-cov-2, to"
10708,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.138888889,"the, of, sars-cov-2, reported, to"
10709,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.138888889,"to, infection, in, humans, and"
10710,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.138888889,"the, of, sars-cov-2, from, and"
10711,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.138888889,"the, two, coronavirus,, and, s"
10712,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.138888889,"with, the, sars-cov-2, closer, in"
10713,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.138888889,"sars-cov-2, is, and, can, be, as, et, al.,, to, that"
10714,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.138888889,"the, zoonotic, spillover, to, a"
10715,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.138888889,"the, a, zoonotic, spillover, to"
10716,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.138888889,"a, zoonotic, the, spillover, to"
10717,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.138888889,"in, the, of, was, host"
10718,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.138888889,"the, intermediate, host, was, of"
10719,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.138888889,"the, of, outbreak, in, from"
10720,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.138888889,"sars-cov-2, to, in, with, bat"
10721,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.138888889,"that, in, the, for, of"
10722,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.138888889,"a, in, the, of, pandemic"
10723,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.138888889,"the, reservoirs, of, bats, and"
10724,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.138888889,"the, of, malayan, as, intermediate"
10725,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.138888889,"the, closely, related, virus, to"
10726,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.138888889,"the, virus, in, and, to"
10727,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.138888889,"and, in, closely, related, the"
10728,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.138888889,"of, to, the, bat, and"
10729,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.138888889,"to, with, a, from, sars-cov-2"
10730,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.138888889,"from, with, appear, to, of"
10731,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.138888889,"is, to, sars-cov-2, whole, genome"
10732,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.138888889,"of, to, sars-cov-2, by, the"
10733,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.138888889,"sars-cov-2, to, the, viruses, of"
10734,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.138888889,"of, viruses, their, to, the"
10735,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.138888889,"of, sars-cov-2, also, to, the"
10736,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.138888889,"sars-cov-2, similarity, to, the, of"
10737,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.138888889,"the, and, is, to, of"
10738,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.138888889,"of, to, that, the, and"
10739,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.138888889,"and, are, the, of, is"
10740,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.138888889,"that, are, the, of, and"
10741,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.138888889,"and, to, the, of, sars-cov-2."
10742,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.138888889,"found, in, the, of, that, closely, related, to, similar, virus"
10743,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.138888889,"have, that, to, with, the"
10744,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.138888889,"of, that, to, the, sars-cov-2."
10745,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.138888889,"the, virus, closely, related, to"
10746,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.138888889,"the, in, to, sars-cov-2, virus"
10747,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.138888889,"from, as, intermediate, that, virus, to, and, the, palm, civets"
10748,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.138888889,"a, genome, from, at, in, province,, the, virus, closely, related, to, of, were, previously, bats"
10749,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.138888889,"the, is, to, and, origin"
10750,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.138888889,"the, spillover, that, animal, at"
10751,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.138888889,"virus, that, is, to, a"
10752,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.138888889,"and, in, to, of, which"
10753,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.138888889,"the, which, to, of, and"
10754,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.138888889,"the, viruses, to, of, their"
10755,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.138888889,"sars-cov-2, a, humans, natural, origin"
10756,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.138888889,"the, sequence, with, a, sars-cov-2"
10757,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.138888889,"that, the, virus, sequence, identity"
10758,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.138888889,"genetic, that, the, virus, is"
10759,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.138888889,"is, that, the, as, of"
10760,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.138888889,"bats, to, the, reservoir, of"
10761,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.138888889,"the, similarity, of, to, its"
10762,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.138888889,"from, its, it, to, not, the, that, may, in, a"
10763,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.138888889,"sars-cov-2, of, natural, the, to, in, binding, ace2, rbd, protein"
10764,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.138888889,"the, of, sars-cov-2, a, r."
10765,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.138888889,"t, that, sars-cov-2, jumped, the"
10766,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.138888889,"the, virus, to, sars-cov-2, in"
10767,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.138888889,"of, the, analysis, that, coronavirus"
10768,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.138888889,"that, from, the, and, animals"
10769,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.138888889,"to, the, that, includes, and"
10770,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.138888889,"of, the, sequence, that, same"
10771,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.138888889,"the, and, that, originated, in"
10772,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.138888889,"bats, to, humans, and, the"
10773,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.138888889,"virus, and, evolutionary, bat, of"
10774,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.138888889,"was, and, to, the, of"
10775,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.138888889,"that, the, of, to, sars-cov-2."
10776,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.138888889,"in, the, two, huanan, market"
10777,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.138888889,"has, been, to, that, in"
10778,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.138888889,"of, a, in, horseshoe, bats"
10779,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.138888889,"the, of, commonly, known, as"
10780,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.138888889,"to, humans, from, and, the"
10781,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.138888889,"is, to, bats, be, the"
10782,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.138888889,"the, from, to, humans, and"
10783,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.138888889,"the, bats, and, to, humans"
10784,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.138888889,"the, and, closely, related, in"
10785,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.138888889,"the, a, market, in, and"
10786,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.138888889,"a, of, patients, the, in"
10787,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.138888889,"that, the, of, is, a"
10788,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.138888889,"a, is, the, that, and"
10789,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.138888889,"and, that, the, covid-19, of"
10790,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.138888889,"is, that, the, of, covid-19"
10791,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.138888889,"available, is, bats, and, the"
10792,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.138888889,"the, of, that, sars-cov-2, virus"
10793,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.138888889,"of, the, virus, to, and"
10794,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.138888889,"bat, host, sars-cov-2, an, intermediate"
10795,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.138888889,"the, that, sars-cov-2, a, of"
10796,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.138888889,"a, of, the, sars-cov-2, that"
10797,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.138888889,"that, the, reservoir, a, of"
10798,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.138888889,"from, a, to, its, in, the, that, it, may, not"
10799,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.138888889,"sars-cov-2, has, been, humans, in"
10800,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.138888889,"the, genetic, that, is, virus"
10801,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.138888889,"of, the, has, and, human"
10802,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.138888889,"the, of, to, sars-cov-2, coronaviruses"
10803,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.138888889,"of, sars-cov-2, sars-cov, and, bat"
10804,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.138888889,"sars-cov-2, in, to, of, which"
10805,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.138888889,"the, also, to, sars-cov-2, of"
10806,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.138888889,"the, that, be, origin, of"
10807,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.138888889,"this, that, the, origin, of"
10808,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.138888889,"results, the, genomic, that, sars-cov-2"
10809,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.138888889,"bats, be, the, hosts, pangolins"
10810,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.138888889,"scientific, evidence, that, sars-cov-2, for"
10811,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.138888889,"in, a, of, to, province,, the, from, bats, at, genome, were, closely, related, previously, virus"
10812,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.138888889,"the, are, very, similar, to"
10813,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.138888889,"the, sars-cov-2, is, to, bat"
10814,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.138888889,"the, that, are, to, sars-cov-2"
10815,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.138888889,"a, that, the, are, to"
10816,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.138888889,"a, to, that, sars-cov-2, the"
10817,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.138888889,"sars-cov-2, bat, very, to, the"
10818,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.138888889,"the, of, a, and, bat"
10819,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.138888889,"the, origin, by, a, in"
10820,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.138888889,"in, the, of, a, patients"
10821,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.138888889,"was, in, yunnan, bat, rhinolophus"
10822,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.138888889,"that, of, sars-cov-2, the, part"
10823,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.138888889,"that, sars-cov-2, the, of, we"
10824,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.138888889,"that, is, the, probable, sars-cov-2"
10825,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.138888889,"the, of, sars-cov-2, bats, and"
10826,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.138888889,"this, the, bat, pangolin, cov"
10827,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.138888889,"this, that, sars-cov-2, originated, in"
10828,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.138888889,"in, the, than, 2, is, that, sars-cov-2, with, and, this"
10829,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.138888889,"the, pangolin, is, to, bat"
10830,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.138888889,"this, bat, cov, pangolin, the"
10831,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.138888889,"for, that, in, the, sars-cov-2"
10832,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.138888889,"the, sars-cov-2, between, and, ratg13"
10833,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.138888889,"between, and, that, the, sars-cov-2"
10834,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.138888889,"is, the, and, similarity, sars-cov-2"
10835,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.138888889,"that, the, sars-cov-2, bat, cov"
10836,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.138888889,"the, that, has, with, bat"
10837,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.138888889,"that, with, the, sars-cov-2, bat"
10838,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.138888889,"the, that, sars-cov-2, has, with"
10839,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.138888889,"this, that, the, of, origin"
10840,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.138888889,"this, and, origin, of, the"
10841,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.138888889,"this, the, and, of, bat"
10842,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.138888889,"this, sars-cov-2, that, originated, in"
10843,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.138888889,"the, genome, of, sars-cov-2, to"
10844,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.138888889,"the, pangolin, to, of, bat"
10845,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.138888889,"of, to, sars-cov-2, and, the"
10846,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.138888889,"sars-cov-2, to, and, the, of"
10847,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.138888889,"and, with, the, of, sars-cov-2"
10848,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.138888889,"the, of, pangolin-cov, bat-sl-cov-2,, with"
10849,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.138888889,"in, of, sars-cov-2, and, the"
10850,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.138888889,"that, the, and, in, sars-cov-2"
10851,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.138888889,"the, in, that, for, sars-cov-2"
10852,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.138888889,"that, the, between, sars-cov-2, and"
10853,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.138888889,"that, sars-cov-2, and, the, of"
10854,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.138888889,"the, of, that, sars-cov, and"
10855,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.138888889,"the, of, and, are, that"
10856,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.138888889,"reservoir, of, that, the, a"
10857,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.138888889,"that, and, the, for, of"
10858,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.138888889,"the, similarity, sars-cov-2, and, is"
10859,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.138888889,"sars-cov-2, and, to, the, in"
10860,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.138888889,"this, and, of, the, in"
10861,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.138888889,"of, that, the, and, virus"
10862,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.138888889,"the, for, in, and, of"
10863,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.138888889,"the, that, of, in, for"
10864,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.138888889,"at, that, the, virus, of"
10865,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.138888889,"with, to, the, of, virus"
10866,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.138888889,"that, sars-cov-2, has, the, with"
10867,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.138888889,"the, of, that, and, bat"
10868,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.138888889,"the, and, this, bat, of"
10869,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.138888889,"sars-cov-2, virus, that, is, in"
10870,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.138888889,"a, from, the, to, with"
10871,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.138888889,"the, of, with, bat-sl-cov-2,, pangolin-cov"
10872,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.138888889,"sars-cov-2, to, from, is, be"
10873,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.138888889,"is, the, sars-cov-2, that, probable"
10874,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.138888889,"sars-cov-2, bat, an, intermediate, host"
10875,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.138888889,"the, that, animal, at, of"
10876,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.138888889,"evidence, scientific, that, for, sars-cov-2"
10877,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.138888889,"the, sars-cov-2, was, that, in"
10878,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.138888889,"the, is, in, of, bat"
10879,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.138888889,"the, of, to, coronavirus, bat"
10880,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.138888889,"the, to, of, sars-, cov-2"
10881,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.138888889,"to, sars-cov-2, in, the, rbd, protein, binding, ace2, of, natural"
10882,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.138888889,"coronaviruses, the, to, of, and"
10883,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.138888889,"the, of, and, to, sars-cov-2."
10884,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.138888889,"the, sars-cov-2, very, to, bat"
10885,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.138888889,"analysis, that, sars-cov-2, is, the"
10886,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.138461538,"made, multiple, by, of, that, sars-cov-2, have, been, a"
10887,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.138461538,"in, to, is, of, the, which, genetic, and, naturally"
10888,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.138461538,"is, a, virus, that, into, with, to, the, for"
10889,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.138461538,"had, it, was, not, by, the, that, been, a"
10890,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.138461538,"at, the, huanan, for, zoonotic, of, sars-cov-2, into, from"
10891,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.138461538,"and, at, the, huanan, likely, that, was, sars-cov-2, in"
10892,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.138461538,"the, of, was, that, were, to, and, more, than"
10893,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.138461538,"to, that, sars-, cov-2, the, of, may, have, sars-cov-2"
10894,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.138461538,"and, a, to, the, coronavirus, of, with, pangolin, respectively"
10895,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.138461538,"the, has, a, of, that, from, to, bat, and"
10896,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.138461538,"the, and, which, to, of, genetic, is, in, naturally"
10897,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.138461538,"the, and, were, that, virus, in, likely, humans, to"
10898,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.138461538,"the, a, of, to, with, coronavirus, pangolin, and, respectively"
10899,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.138461538,"the, genome, of, sars-cov, and, bat, a, sequence, in"
10900,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.138461538,"a, genome, from, in, province,, china, the, virus, of"
10901,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.138461538,"genome, a, sequence, and, sars-cov, the, of, bat, in"
10902,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.138461538,"and, a, similarity, of, sars-cov-2, receptor, which, the, genomes"
10903,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.138461538,"in, a, of, sars-cov-2, found, to, with, coronavirus, that"
10904,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.138461538,"in, the, of, an, from, humans, were, to, and"
10905,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.138461538,"the, were, likely, to, that, virus, in, and, humans"
10906,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.138461538,"more, than, of, the, were, to, and, that, was"
10907,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.138461538,"in, an, from, of, were, to, and, the, humans"
10908,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.138461538,"palm, civets, were, infected, from, in, the, china, wet, a, while, or, at, markets., and, of, animal, markets"
10909,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.138461538,"at, infected, a, palm, civets, from, animal, in, the, or, wet, markets, china, while, were, of, markets., and"
10910,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.138461538,"the, for, of, sars-cov-2, into, zoonotic, from, at, huanan"
10911,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.138461538,"the, sars-cov-2, at, huanan, was, likely, that, in, and"
10912,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.138461538,"a, for, the, is, virus, with, that, to, into"
10913,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.138461538,"the, as, a, species, of, that, from, bat, hosts"
10914,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.138461538,"these, 2, viruses, to, the, in, and, that, bats"
10915,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.138461538,"the, has, a, of, to, that, from, and, bat"
10916,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.138461538,"of, that, the, bat, a, from, species, as, hosts"
10917,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.138461538,"that, been, by, a, of, to, and, the, hosts"
10918,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.138461538,"that, a, made, of, sars-cov-2, have, been, by, multiple"
10919,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.138461538,"not, a, that, the, was, it, had, been, by"
10920,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.138461538,"genome, a, the, of, virus, from, in, province,, china"
10921,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.138461538,"the, similarity, of, genomes, sars-cov-2, and, receptor, which, a"
10922,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.138461538,"the, been, a, of, that, to, by, hosts, and"
10923,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.138461538,"viruses, to, the, 2, in, bats, and, that, these"
10924,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.138461538,"and, from, that, the, of, coronavirus, bats, likely, sars-cov-2"
10925,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.138461538,"shows, that, sars-cov-2, the, closest, with, of, and, to"
10926,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.138461538,"sars-, cov-2, the, of, that, sars-cov-2, may, have, to"
10927,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.138461538,"that, of, to, a, coronavirus, found, in, with, sars-cov-2"
10928,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.138461538,"that, the, of, sars-cov-2, and, coronavirus, likely, from, bats"
10929,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.138297872,"the, and, has, a, resulting, in, ability, to, ace2, receptors, that, not, of"
10930,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.138297872,"that, were, infected, in, the, china, market, a, or, animals, of, source, may"
10931,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.138297872,"that, the, infected, in, china, may, market, animals, were, or, a, source, of"
10932,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.138297872,"of, has, to, ace2, receptors, a, that, not, resulting, in, and, ability, the"
10933,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.137931034,"reservoir, of, a, viruses"
10934,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.137931034,"to, in, sars-cov-2, and"
10935,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.137931034,"the, and, similar, to, sars-, cov-2, genetic, many"
10936,"In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.137931034,"in, to, more, than"
10937,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.137931034,"the, are, also, of"
10938,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.137931034,"the, of, in, china"
10939,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.137931034,"and, sars-cov, with, the, of, virus, from, bat"
10940,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.137931034,"sars-cov-2, is, to, have, in, the, bat, which"
10941,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.137931034,"that, sars-cov-2, is, naturally"
10942,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.137931034,"natural, of, has, been"
10943,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.137931034,"of, a, reservoir, viruses"
10944,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.137931034,"genomic, are, to, of"
10945,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.137931034,"of, similar, to, sars-cov-2"
10946,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.137931034,"to, are, most, sars-cov-2"
10947,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.137931034,"the, intermediate, of, as"
10948,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.137931034,"of, from, bats, to, humans, intermediate, sars-cov-2, the"
10949,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.137931034,"this, that, were, infected, in, the, wet, market, large, of, animal, on"
10950,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.137931034,"of, the, sars-, and"
10951,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.137931034,"the, of, and, sars-"
10952,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.137931034,"the, are, and, of"
10953,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.137931034,"and, are, the, of"
10954,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.137931034,"the, reservoirs, and, of"
10955,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.137931034,"the, virus, for, to, that, from, and, respectively"
10956,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.137931034,"that, the, from, species, as, intermediate, hosts, for"
10957,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.137931034,"that, virus, to, and, the, intermediate, hosts, for"
10958,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",zoonotic origins of SARS-CoV-2 by natural evolution,0.137931034,"of, natural, zoonotic, sars-cov-2"
10959,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.137931034,"the, is, to, origin"
10960,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.137931034,"coronavirus, with, to, sars-cov-2"
10961,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.137931034,"the, of, and, other"
10962,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.137931034,"to, and, in, the"
10963,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.137931034,"the, sars-cov, and, other"
10964,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.137931034,"the, and, to, sars-cov"
10965,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.137931034,"from, animals, in, the"
10966,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.137931034,"from, animals, humans, the"
10967,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.137931034,"that, the, of, bat"
10968,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.137931034,"in, the, that, sars-cov-2, is, of, shows, bat"
10969,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.137931034,"the, in, that, bat"
10970,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.137931034,"sars-cov-2, that, is, bat"
10971,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.137931034,"sars-cov-2, genome, to, sars-cov"
10972,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.137931034,"that, the, bats, of"
10973,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.137931034,"that, the, outbreak, of"
10974,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","civet cats and raccoon dogs  

are the intermediate hosts",0.137931034,"the, raccoon, dogs, intermediate"
10975,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.137931034,"the, of, to, bats"
10976,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.137931034,"sars-cov-2, the, and, animal"
10977,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","with the first case being linked to  

a seafood market",0.137931034,"the, a, with, to"
10978,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.137931034,"the, origin, a, and"
10979,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.137931034,"the, that, to, sars-cov-2"
10980,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.137931034,"the, of, sars-cov-2, that"
10981,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.137931034,"the, of, bat, that, a, viruses, are, to"
10982,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.137931034,"of, 2019,, to, and, the, huanan, market, known"
10983,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.137931034,"the, to, be, market"
10984,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.137931034,"to, show, that, in"
10985,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.137931034,"cases, a, to, the, huanan, market, in, earliest"
10986,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.137931034,"the, to, in, market"
10987,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.137931034,"of, with, a, and, the, huanan, market, in"
10988,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.137931034,"the, is, in, market"
10989,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.137931034,"and, had, in, animal"
10990,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.137931034,"or, of, the, natural"
10991,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.137931034,"the, of, sars-cov-2, to, may, also, humans, spread"
10992,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.137931034,"two, of, the, sars-cov-2, lineage, have, in, from"
10993,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.137931034,"one, also, that, the, of, may, have, to"
10994,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.137931034,"to, that, covid-19, in"
10995,"expended to make the simple point 

that COVID-19 had a natural origin.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.137931034,"to, that, covid-19, a"
10996,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.137931034,"covid-19, is, to, in"
10997,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.137931034,"of, as, from, and"
10998,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.137931034,"coronavirus, to, human, animals"
10999,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.137931034,"animals, and, to, through"
11000,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.137931034,"from, to, is, and"
11001,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.137931034,"the, of, as, intermediate"
11002,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.137931034,"the, known, be, as"
11003,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.137931034,"the, was, as, animal"
11004,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.137931034,"from, that, virus, to, for, and, the, respectively"
11005,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.137931034,"genome, of, the, covid-19, virus, from, with, and"
11006,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.137931034,"from, the, have, been"
11007,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.137931034,"a, from, to, the"
11008,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.137931034,"the, a, has, been"
11009,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.137931034,"the, sars-cov-2, with, to"
11010,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.137931034,"the, with, similarity, sars-cov-2"
11011,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.137931034,"sars-cov-2, the, identity, with"
11012,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.137931034,"bat, has, with, sars-cov-2"
11013,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.137931034,"genetic, has, to, that"
11014,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.137931034,"sars-cov-2, of, the, and, to, virus, genetic, analysis"
11015,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.137931034,"the, of, and, to"
11016,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.137931034,"to, be, the, of"
11017,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.137931034,"the, of, to, be"
11018,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.137931034,"the, of, is, to, that, sars-cov-2, undergoing, and"
11019,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.137931034,"and, of, sars-cov-2, which, is, an, the, to"
11020,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.137931034,"virus, its, in, bats"
11021,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.137931034,"in, show, that, to"
11022,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.137931034,"that, covid-19, in, to"
11023,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.137931034,"genetic, to, has, that"
11024,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.137931034,"the, that, at, of"
11025,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.137931034,"to, the, is, origin"
11026,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.137931034,"is, that, the, virus"
11027,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.137931034,"that, the, is, and"
11028,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.137931034,"the, bat, and, with"
11029,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.137931034,"of, the, that, bats"
11030,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.137931034,"the, virus, to, identity"
11031,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.137931034,"that, bats, the, of"
11032,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.137931034,"the, in, from, animals"
11033,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.137931034,"from, the, been, have"
11034,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.137931034,"the, coronavirus, to, human"
11035,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.137931034,"evolutionary, of, to, the"
11036,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.137931034,"the, of, for, more, than, is, to, human"
11037,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.137931034,"is, to, bat, sars-cov"
11038,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Scientific reports published so far include  

hosts, such as bats (28), pangolins (29), cats  

(11), and dogs (30)",0.137931034,"scientific, bats, and, pangolins"
11039,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.137931034,"the, that, of, bat"
11040,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.137931034,"the, of, coronaviruses, from"
11041,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.137931034,"the, that, derived, from"
11042,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.137931034,"the, genome, sequence, of, that, to, bat, and"
11043,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.137931034,"pan-, golin, that, to"
11044,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.137931034,"have, shown, that, to"
11045,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.137931034,"bats, the, most, reservoir"
11046,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.137931034,"a, an, animal, zoonotic"
11047,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.137931034,"is, that, a, to"
11048,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.137931034,"is, that, to, a"
11049,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.137931034,"the, humans, from, animals"
11050,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.137931034,"the, to, animals, a"
11051,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.137931034,"the, virus, for, to"
11052,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.137931034,"the, of, bats, to"
11053,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.137931034,"closely, related, in, bats"
11054,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.137931034,"suggest, that, origin, bat"
11055,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.137931034,"evidence, that, and, sars-cov-2"
11056,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.137931034,"its, virus, bats, in"
11057,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.137931034,"the, animal, sars-cov-2, and"
11058,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.137931034,"is, that, species, the"
11059,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.137931034,"the, sars-cov-2, is, and"
11060,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.137931034,"another, sars-cov-2, the, and"
11061,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.137931034,"in, the, of, virus, with, human, and, this"
11062,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.137931034,"the, virus, covid-19, genome, of, with, from, and"
11063,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.137931034,"the, to, be, of"
11064,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.137931034,"the, reservoir, be, of"
11065,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.137931034,"results, that, the, of"
11066,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.137931034,"the, and, of, genome, sequence, to, that, bat"
11067,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.137931034,"in, of, sars-related, coronaviruses."
11068,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.137931034,"animal, to, sars-cov-2, in"
11069,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.137931034,"genomic, of, are, to"
11070,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.137931034,"with, the, of, and, sars-cov, from, bat, virus"
11071,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.137931034,"is, that, a, sars-cov-2"
11072,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.137931034,"this, that, in, virus"
11073,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.137931034,"a, viruses, are, to, bat, that, the, of"
11074,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.137931034,"of, the, in, and, that, sequences, a, viruses"
11075,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.137931034,"other, the, of, and"
11076,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.137931034,"of, the, and, sars-cov-2"
11077,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.137931034,"the, are, sars-cov-2, of"
11078,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.137931034,"sars-cov-2, and, animal, humans"
11079,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.137931034,"are, the, hosts, sars-cov-2"
11080,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.137931034,"the, sars-cov-2, and, of"
11081,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Bats are natural hosts of many of the known  

coronaviruses",0.137931034,"of, bats, the, known"
11082,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.137931034,"coronaviruses, that, to, sars-cov-2, in, bats, and, from"
11083,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.137931034,"the, has, been, a, of, that, to, and"
11084,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.137931034,"that, pan-, golin, to"
11085,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.137931034,"that, of, a, coronavirus"
11086,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.137931034,"related, are, closely, to"
11087,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.137931034,"results, of, the, that"
11088,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.137931034,"be, the, of, may"
11089,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.137931034,"sars-cov-2, the, of, with"
11090,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.137931034,"to, sars-cov-2, belonging, the"
11091,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.137931034,"the, bat, rhinolophus, in"
11092,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.137931034,"in, closely, related, bats"
11093,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.137931034,"closely, related, sars-cov-2, in"
11094,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.137931034,"at, that, the, of"
11095,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.137931034,"be, the, reservoir, of"
11096,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.137931034,"has, been, natural, of"
11097,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.137931034,"been, of, the, for"
11098,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.137931034,"the, origin, and, a"
11099,"insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.137931034,"from, of, as, and"
11100,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.137931034,"from, between, and, the"
11101,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.137931034,"coronavirus, animals, to, human"
11102,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.137931034,"the, to, human, coronavirus"
11103,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.137931034,"a, animals, to, the"
11104,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K",0.137931034,"more, than, to, in"
11105,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.137931034,"a, the, has, been"
11106,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.137931034,"and, the, reservoirs, of"
11107,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.137931034,"genome, sars-cov-2, sars-cov, to"
11108,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.137931034,"a, sars-cov-2, to, or"
11109,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.137931034,"sars-cov-2, is, to, the"
11110,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.137931034,"the, of, and, that, sars-cov-2, is, to, undergoing"
11111,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.137931034,"the, of, is, more, than, to, human, for"
11112,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.137931034,"human, and, this, virus, with, the, in, of"
11113,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.137931034,"the, is, that, in, for, of, 2, to, and, with, a, not"
11114,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.137931034,"to, the, of, sars-cov-2, from, bats, intermediate, humans"
11115,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.137931034,"the, of, sequences, in, from, that, intermediate, host"
11116,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.137931034,"of, the, in, that, sars-cov-2, sequences, a, with"
11117,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.137931034,"to, the, that, sars-cov-2"
11118,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.137931034,"to, that, sars-cov-2, the"
11119,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.137931034,"to, the, with, from"
11120,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.137931034,"the, virus, identity, to"
11121,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.137931034,"to, sars-cov-2, found, in"
11122,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.137931034,"and, (2020), also, sars-cov-2, in, an, the, to"
11123,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","bats are also important reservoir species for a great 

range of coronaviruses",0.137931034,"also, bats, are, for"
11124,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.137931034,"with, bat, and, the"
11125,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.137931034,"amino, at, the, s1/s2, cleavage, in, furin, insertion"
11126,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.137931034,"from, in, is, similar, at, the, amino, acid"
11127,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.137931034,"sars-cov-2, that, humans, with, on, to, the, for"
11128,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.137931034,"humans, also, spread, the, of, sars-cov-2, may, to"
11129,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.137931034,"the, host, an, intermediate"
11130,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.137931034,"sars-cov-2, to, in, animal"
11131,"civet cats and raccoon dogs  

are the intermediate hosts","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.137931034,"raccoon, dogs, the, intermediate"
11132,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.137931034,"that, of, from, intermediate, host, in, sequences, the"
11133,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.137931034,"from, was, at, market, in, that, the, of"
11134,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.137931034,"to, with, coronavirus, sars-cov-2"
11135,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.137931034,"found, to, sars-cov-2, in"
11136,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.137931034,"bat, similarity, with, sars-cov-2"
11137,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.137931034,"similarity, sars-cov-2, with, to"
11138,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",Wet Market animals maintained in poor conditions,0.137931034,"in, animals, wet, market"
11139,zoonotic origins of SARS-CoV-2 by natural evolution,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.137931034,"zoonotic, of, sars-cov-2, natural"
11140,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.137931034,"the, of, and, for"
11141,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.137931034,"animal, as, the, for"
11142,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.137931034,"most, sars-cov-2, are, to"
11143,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.137931034,"virus, to, for, the"
11144,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.137931034,"the, for, and, other"
11145,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.137931034,"for, and, in, the"
11146,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.137931034,"in, southern, between, and, by, different, sars-cov-2-like, viruses"
11147,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.137931034,"and, a, of, between, in, region, the, viruses"
11148,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.137931034,"the, by, was, a, at, and, to, with"
11149,"This suggests that the BANAL series may be able to directly infect  

humans.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.137931034,"the, banal, series, to"
11150,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.137931034,"sars-cov-2, viruses, are, to"
11151,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.137931034,"that, are, to, and"
11152,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","This suggests that the BANAL series may be able to directly infect  

humans.",0.137931034,"this, suggests, that, the"
11153,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.137931034,"the, most, known, be"
11154,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.137931034,"sars-cov-2, be, virus, the"
11155,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.137931034,"in, to, be, closely, related, the, is, sars-cov-2"
11156,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.137931034,"was, by, a, with, and, to, at, the"
11157,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.137931034,"on, the, large, of, infected, that, were, wet, animal, market, in, this"
11158,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.137931034,"in, the, of, for, 2, is, not, to, that, with, and, a"
11159,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.137931034,"2019,, the, huanan, market, known, to, and, of"
11160,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.137931034,"in, a, the, earliest, cases, to, huanan, market"
11161,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.137931034,"that, for, sars-cov-2, to, humans, on, the, with"
11162,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","expended to make the simple point 

that COVID-19 had a natural origin.",0.137931034,"a, that, the, to"
11163,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","expended to make the simple point 

that COVID-19 had a natural origin.",0.137931034,"that, covid-19, a, to"
11164,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","expended to make the simple point 

that COVID-19 had a natural origin.",0.137931034,"a, to, that, the"
11165,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","expended to make the simple point 

that COVID-19 had a natural origin.",0.137931034,"a, natural, to, the"
11166,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.137931034,"sars-cov-2, and, coronaviruses, from, to, that, in, bats"
11167,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.137931034,"coronaviruses, found, in, bats, to, that, sars-cov-2, and"
11168,"expended to make the simple point 

that COVID-19 had a natural origin.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.137931034,"to, the, a, natural"
11169,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.137931034,"an, animal, a, zoonotic"
11170,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.137931034,"sars-cov-2, animal, and, humans"
11171,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.137931034,"a, coronavirus, that, of"
11172,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.137931034,"the, of, been, for"
11173,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.137931034,"that, the, derived, from"
11174,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.137931034,",, the, spike, in, a, to, sars-cov-2,, that"
11175,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","In the 

case of MERS, dromedaries were the principal host.",0.137931034,"in, of, were, the"
11176,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",The COVID-19 most likely developed from bat origin coronaviruses,0.137931034,"origin, the, most, likely"
11177,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.137931034,"from, as, intermediate, hosts, that, for, the, species"
11178,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.137931034,"to, the, in, bats, of, and, that, covid-19"
11179,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.137931034,"and, animals, to, through"
11180,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.137931034,"the, market, to, be"
11181,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.137931034,"in, the, to, market"
11182,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.137931034,"is, the, market, in"
11183,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.137931034,"is, covid-19, in, to"
11184,"According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.137931034,"to, the, evolutionary, of"
11185,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.137931034,"that, the, covid-19, in, bats, and, to, of"
11186,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.137931034,"that, the, of, and, coronavirus, been, viruses, bats"
11187,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.137931034,"the, in, of, china"
11188,"Bats are natural hosts of many of the known  

coronaviruses","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.137931034,"bats, of, the, known"
11189,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.137931034,"the, that, is, of"
11190,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.137931034,"of, the, or, natural"
11191,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.137931034,"is, that, the, species"
11192,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.137931034,"of, the, that, is"
11193,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.137931034,"in, the, bat, rhinolophus"
11194,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.137931034,"is, and, from, to"
11195,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.137931034,"the, between, from, and"
11196,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.137931034,"the, is, and, to"
11197,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.137931034,"from, in, two, lineage, the, of, sars-cov-2, have"
11198,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.137931034,"at, the, amino, acid, in, from, is, similar"
11199,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.137931034,"of, sars-cov-2, in, receptor, binding, is, the, viral"
11200,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.137931034,"and, southern, sars-cov-2-like, viruses, by, different, between, in"
11201,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.137931034,"of, the, outbreak, that"
11202,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.137931034,"the, is, and, that"
11203,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.137931034,"the, that, to, a, of, and, has, been"
11204,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.137931034,"is, the, and, bats"
11205,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.137931034,"sars-cov-2, a, virus, the"
11206,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.137931034,"more, likely, origin, of"
11207,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.137931034,"that, is, to, a"
11208,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.137931034,"sars-cov-2, a, to, or"
11209,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.137931034,"the, to, be, sars-cov-2"
11210,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.137931034,"sars-cov-2, was, to, the"
11211,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.137931034,"sars-cov-2, bat, to, the"
11212,The COVID-19 most likely developed from bat origin coronaviruses,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.137931034,"the, most, likely, origin"
11213,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.137931034,"have, been, by, of, to, and, the, sars-cov-2"
11214,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.137931034,"viruses, are, to, sars-cov-2"
11215,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.137931034,"and, are, to, that"
11216,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.137931034,"that, are, sars-cov-2, to"
11217,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.137931034,"coronaviruses, that, to, sars-cov-2, found, in, bats, and"
11218,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.137931034,"bat, with, similarity, sars-cov-2"
11219,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.137931034,"the, be, known, as"
11220,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.137931034,"sars-cov-2, of, the, emergence, to, in, ace2, rbd"
11221,"Scientific reports published so far include  

hosts, such as bats (28), pangolins (29), cats  

(11), and dogs (30)","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.137931034,"scientific, bats, pangolins, and"
11222,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.137931034,"evidence, that, sars-cov-2, and"
11223,"bats are also important reservoir species for a great 

range of coronaviruses","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.137931034,"bats, are, also, for"
11224,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.137931034,"the, of, in, from, market, that, was, at"
11225,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.137931034,"of, a, that, the, virus, to, sars-like, covs"
11226,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.137931034,"the, most, reservoir, bats"
11227,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.137931034,"the, sars-cov-2, are, hosts"
11228,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.137931034,"sars-cov-2, that, are, to"
11229,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.137931034,"a, that, the, virus, to, of, sars-like, covs"
11230,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.137931034,"the, of, and, sars-cov-2, is, an, which, to"
11231,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.137931034,"(2020), in, to, the, sars-cov-2, also, and, an"
11232,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.137931034,"region, of, and, viruses, a, between, in, the"
11233,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.137931034,"in, is, sars-cov-2, the, of, receptor, binding, viral"
11234,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.137931034,"intermediate, hosts, that, virus, to, for, and, the"
11235,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.137931034,"have, been, by, and, to, the, of, sars-cov-2"
11236,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.137931034,"a, of, for, sars-cov-2, to, with, that, may"
11237,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.137931034,"sars-cov-2, to, belonging, the"
11238,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.137931034,"the, of, and, that, sequences, a, in, viruses"
11239,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.137931034,"that, of, a, in, with, sars-cov-2, sequences, the"
11240,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.137931034,"sars-cov-2, is, that, naturally"
11241,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.137931034,"the, sars-cov-2, is, of"
11242,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.137931034,"of, that, sars-cov-2, the"
11243,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.137931034,"of, the, sars-cov-2, that"
11244,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.137931034,"the, that, of, sars-cov-2"
11245,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.137931034,"viruses, the, coronavirus, been, bats, of, and, that"
11246,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.137931034,"the, sars-cov-2, which, have, to, is, in, bat"
11247,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.137931034,"the, shows, that, sars-cov-2, is, in, of, bat"
11248,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.137931034,"this, pangolin, the, of"
11249,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.137931034,"that, the, origin, sars-cov-2"
11250,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.137931034,"origin, of, more, likely"
11251,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.137931034,"that, sars-cov-2, the, origin"
11252,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.137931034,"evidence, that, the, of, may, have, to, as"
11253,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.137931034,"the, and, also, a, to, that, are, of"
11254,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.137931034,"sars-cov-2, with, and, to"
11255,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.137931034,"the, sars-cov, and, to"
11256,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.137931034,"the, to, with, sars-cov-2"
11257,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.137931034,"sars-cov-2, to, and, with"
11258,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.137931034,"is, sars-cov-2, the, and"
11259,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.137931034,"of, the, sars-cov-2, is"
11260,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.137931034,"the, for, and, in"
11261,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.137931034,"the, in, that, for"
11262,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.137931034,"sars-cov-2, between, the, and"
11263,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.137931034,"the, similarity, with, sars-cov-2"
11264,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.137931034,"sars-cov-2, recombinant, the, and"
11265,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.137931034,"and, sars-cov-2, in, to"
11266,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.137931034,"the, pangolin-cov, and, sars-cov-2"
11267,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.137931034,"the, are, to, sars-cov-2"
11268,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.137931034,"the, and, are, to"
11269,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.137931034,"are, the, sars-cov-2, to"
11270,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.137931034,"virus, that, in, this"
11271,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.137931034,"this, the, pangolin, of"
11272,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.137931034,"the, that, in, bat"
11273,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.137931034,"the, animal, was, as"
11274,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.137931034,"for, that, in, the"
11275,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.137931034,"the, an, intermediate, host"
11276,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.137931034,"sars-cov-2, the, and, another"
11277,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.137931034,"the, virus, sars-cov-2, be"
11278,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.137931034,"the, sars-cov-2, a, virus"
11279,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.137931034,"between, and, the, sars-cov-2"
11280,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.137931034,"the, and, recombinant, sars-cov-2"
11281,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.137931034,"that, may, a, of, with, to, for, sars-cov-2"
11282,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.137931034,"the, insertion, in, furin, amino, at, s1/s2, cleavage"
11283,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.137931034,"a, ,, to, sars-cov-2,, spike, in, the, that"
11284,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.137931034,"is, the, closely, related, to, sars-cov-2, be, in"
11285,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.137931034,"that, are, also, to, and, a, the, of"
11286,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.137931034,"also, one, the, of, that, may, have, to"
11287,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.137931034,"evidence, to, that, the, of, may, have, as"
11288,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.137931034,"the, and, many, genetic, similar, to, sars-, cov-2"
11289,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.137931034,"analysis, of, genetic, to, sars-cov-2, the, and, virus"
11290,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.137931034,"rbd, of, sars-cov-2, to, ace2, the, emergence, in"
11291,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.137681159,"at, bat, had, to, a, from, in, tested, for, the, virus, collected, identified, sars, were, one, of, and, other"
11292,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.137681159,"the, live, to, in, create, a, for, of, as, researchers, with, time, sars, was, that, virus, by, yunnan, and"
11293,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.137681159,"in, a, of, one, to, the, collected, from, tested, for, identified, bat, and, had, sars, at, were, other, virus"
11294,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.137681159,"the, was, for, time, to, a, live, virus, that, with, as, and, researchers, create, by, sars, in, of, yunnan"
11295,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.1375,"the, market, is, wuhan, that, in, of, were, exposed, to, covid-19"
11296,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.1375,"in, with, the, to, that, sars-cov-2, is, of, pangolin, sars-, cov-2"
11297,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.1375,"the, huanan, market, in, of, cases, were, to, with, known, covid-19"
11298,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.1375,"the, of, that, were, exposed, to, market, in, wuhan, is, covid-19"
11299,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.1375,"of, the, known, covid-19, cases, in, to, were, with, huanan, market"
11300,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.1375,"that, of, sars-, cov-2, to, is, in, pangolin, with, sars-cov-2, the"
11301,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.137254902,"data, that, directly, from, a, evolved, in"
11302,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.137254902,"the, of, sars-cov-2,, that, directly, from, bats"
11303,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.137254902,"the, most, reservoirs, of, southeast, asia, and"
11304,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.137254902,"to, sars-, cov-2, the, sarbecovirus, and, are"
11305,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.137254902,"to, humans,, the, of, from, spillover, seems"
11306,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.137254902,"of, the, virus, to, which, bat, and"
11307,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.137254902,"is, no, that, the, had, sars-cov-2, before"
11308,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.137254902,"the, of, human, to, and, these, viruses"
11309,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.137254902,"it, was, a, to, sars-cov-2, the, genome"
11310,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.137254902,"bat, cov, ratg13, the, same, sars-cov-2, that"
11311,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.137254902,"that, the, in, used, as, a, of"
11312,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.137254902,"in, the, of, that, has, human, a"
11313,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.137254902,"was, discovered, in, a, and, to, the"
11314,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.137254902,"seems, to, the, of, humans,, from, spillover"
11315,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.137254902,"of, the, from, as, intermediate, hosts, for"
11316,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.137254902,"of, to, the, intermediate, hosts, for, sars-cov-2"
11317,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.137254902,"on, the, of, that, is, animal, to"
11318,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.137254902,"that, the, in, to, people, infected, market"
11319,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.137254902,"is, it, likely, that, of, to, animal"
11320,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.137254902,"and, a, to, the, coronavirus, be, of"
11321,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.137254902,"that, the, of, sars-cov-2, and, is, to"
11322,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.137254902,"the, to, coronavirus, and, that, was, a"
11323,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.137254902,"can, be, to, bats, of, and, are"
11324,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.137254902,"through, the, in, bats, to, humans, from"
11325,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.137254902,"is, humans, of, sars-cov-2, to, through, be"
11326,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.137254902,"from, pangolins, in, is, sars-cov-2, the, of"
11327,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.137254902,"sars-cov-2, animal, reservoir, likely, seen, in, and"
11328,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.137254902,"a, from, south, china, identified, similarity, sars-cov-2"
11329,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.137254902,"to, sars-cov-2, the, that, result, of, natural"
11330,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.137254902,"the, that, of, natural, sars-cov-2, as, hypothesis"
11331,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.137254902,"the, a, of, to, that, from, bat"
11332,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.137254902,"the, of, sars-cov-2, to, a, that, this"
11333,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.137254902,"that, a, of, to, are, the, sars-cov-2"
11334,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.137254902,"to, that, the, of, and, are, sars-cov-2"
11335,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.137254902,"in, of, support, sars-cov-2, and, the, humans"
11336,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.137254902,"the, of, in, market, early, that, at"
11337,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.137254902,"the, presence, in, of, that, sars-cov-2, jumped"
11338,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.137254902,"the, of, huanan, market, lineage, sample, at"
11339,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.137254902,"sars-cov-2, animal, reservoir, seen, likely, and, in"
11340,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.137254902,"the, of, zoonotic, spillover, to, a, in"
11341,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.137254902,"the, and, of, a, zoonotic, spillover, to"
11342,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.137254902,"a, zoonotic, and, in, the, spillover, to"
11343,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.137254902,"samples, from, the, that, of, in, sars-cov-2"
11344,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.137254902,"of, sars-cov-2, also, to, the, in, animals"
11345,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.137254902,"that, there, is, in, from, an, to"
11346,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.137254902,"there, that, an, to, from, is, in"
11347,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.137254902,"he, of, sars-cov-2, but, that, the, a"
11348,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.137254902,"that, of, species, infect, a, giving, to"
11349,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.137254902,"the, a, coronavirus, was, that, to, and"
11350,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.137254902,"is, to, the, that, from, and, be"
11351,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.137254902,"a, to, bat, that, the, of, from"
11352,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.137254902,"comparative, analysis, the, of, a, suggested, that"
11353,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.137254902,"on, the, of, that, to, animal, is"
11354,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.137254902,"the, infected, people, that, to, market, in"
11355,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.137254902,"the, to, humans, from, bats, through, in"
11356,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.137254902,"bats, and, have, the, from, in, china"
11357,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.137254902,"believe, that, the, of, origins, covid-19, to"
11358,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.137254902,"intermediate, host, and, previous, the, palm, civet"
11359,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.137254902,"the, reservoir, for, a, of, sars-cov, and"
11360,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.137254902,"in, the, of, that, as, a, used"
11361,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.137254902,"that, the, of, novel, coronavirus, viruses, bats"
11362,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.137254902,"to, and, a, the, which, is, same"
11363,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.137254902,"sars-cov-2, is, a, that, to, the, for"
11364,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.137254902,"bat, coronavirus, to, is, similar, the, genome"
11365,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.137254902,"of, the, sequence, analysis, that, sars-cov-2, beta"
11366,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.137254902,"the, has, that, bat, coronaviruses, are, of"
11367,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.137254902,"genome, the, bat, of, virus, between, and"
11368,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.137254902,"the, of, in, same, as, viruses, a"
11369,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.137254902,"binding, of, is, most, likely, on, that"
11370,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.137254902,"in, the, virus, to, been, human, and"
11371,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.137254902,"of, that, to, animal, it, is, likely"
11372,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.137254902,"sars-cov-2, to, humans, through, of, is, be"
11373,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.137254902,"the, of, from, and, in, with, genome"
11374,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.137254902,"to, be, a, of, coronavirus, and, the"
11375,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.137254902,"the, of, with, coronaviruses, to, be, natural"
11376,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.137254902,"sequence, beta, that, the, of, sars-cov-2, analysis"
11377,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.137254902,"of, that, to, the, bat, and, was"
11378,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.137254902,"the, of, virus, to, that, has, and"
11379,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.137254902,"the, of, sars-cov-2, a, with, bat, genome"
11380,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.137254902,"the, of, sars-cov-2, a, virus, has, in"
11381,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.137254902,"a, comparative, analysis, of, suggested, that, the"
11382,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.137254902,"sars-cov-2, et, al.,, 2020), and, the, of"
11383,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.137254902,"sars-cov-2, from, a, identified, similarity, china, south"
11384,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.137254902,"been, and, to, the, of, has, is"
11385,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.137254902,"the, of, sars-cov-2, and, et, al.,, 2020)"
11386,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.137254902,"et, in, to, the, sars-cov-2, from, an"
11387,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.137254902,"the, sample, was, from, a, to, of"
11388,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.137254902,"sars-cov-2, virus, that, found, its, to, the"
11389,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.137254902,"the, viruses, and, of, these, to, human"
11390,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.137254902,"is, that, sars-cov-2, no, had, the, before"
11391,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.137254902,"the, virus, 2, to, sars-cov-2, been, and"
11392,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.137254902,"was, by, and, to, sars-cov-2, the, genome"
11393,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.137254902,"in, the, of, that, has, a, human"
11394,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.137254902,"the, virus, been, human, in, to, and"
11395,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.137254902,"to, virus, 2, been, and, the, sars-cov-2"
11396,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.137254902,"to, a, change, in, the, human, for"
11397,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.137254902,"a, virus, that, with, the, sars-cov-2, in"
11398,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.137254902,"the, of, to, it, is, that, for"
11399,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.137254902,"the, of, more, than, to, and, in"
11400,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.137254902,"that, sars-cov-2, not, a, to, it, in"
11401,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.137254902,"from, bats, to, humans, is, direct, the"
11402,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.137254902,"analysis, suggests, that, the, is, sars-cov-2, a"
11403,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.137254902,"genome, of, the, from, in, with, and"
11404,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.137254902,"the, to, sars-cov-2, in, from, an, et"
11405,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.137254902,"the, from, sars-cov-2, to, cluster, also, and"
11406,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.137254902,"the, of, and, support, sars-cov-2, humans, in"
11407,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.137254902,"in, the, for, to, human, change, a"
11408,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.137254902,"that, the, hosts, for, sars-cov-2, as, a"
11409,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.137254902,"the, was, a, who, and, to, of"
11410,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.137254902,"the, huanan, seafood, market, to, of, with"
11411,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.137254902,"the, of, early, market, that, at, in"
11412,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.137254902,"samples, from, in, the, of, that, sars-cov-2"
11413,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.137254902,"the, in, a, zoonotic, spillover, to, of"
11414,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.137254902,"in, to, the, of, sars-cov-2, natural, is"
11415,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.137254902,"the, reservoirs, of, asia, and, southeast, most"
11416,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.137254902,"a, that, infect, species, of, giving, to"
11417,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.137254902,"the, origins, of, covid-19, to, that, believe"
11418,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.137254902,"of, the, same, as, in, viruses, a"
11419,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.137254902,"that, the, of, closely, a, bat, covid-19"
11420,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.137254902,"the, genome, coronavirus, is, similar, to, bat"
11421,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.137254902,"was, the, genome, sars-cov-2, to, a, it"
11422,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.137254902,"a, the, to, discovered, in, and, was"
11423,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.137254902,"to, by, and, genome, was, the, sars-cov-2"
11424,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.137254902,"a, the, same, and, to, which, is"
11425,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.137254902,"a, genomic, with, the, sars-cov-2, in, bat"
11426,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.137254902,"the, to, was, from, sample, of, a"
11427,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.137254902,"who, the, of, a, was, and, to"
11428,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.137254902,"of, the, to, with, huanan, seafood, market"
11429,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.137254902,"the, identified, as, a, species, of, from, bats,, to, civets, infected, by, bat, and"
11430,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.137254902,"and, environmental, samples, at, the, huanan, seafood, its, was, for, of, in, from, a"
11431,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.137254902,"the, a, zoonotic, spillover, to, of, and"
11432,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.137254902,"the, in, a, zoonotic, spillover, to, and"
11433,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.137254902,"of, lineage, at, the, huanan, market, sample"
11434,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.137254902,"for, and, from, environmental, samples, at, the, huanan, seafood, in, of, its, a, was"
11435,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.137254902,"a, that, the, sars-cov-2, for, to, is"
11436,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.137254902,"found, its, the, that, sars-cov-2, to, virus"
11437,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.137254902,"in, the, virus, that, sars-cov-2, with, a"
11438,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.137254902,"a, genomic, in, with, sars-cov-2, the, bat"
11439,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.137254902,"a, to, that, the, of, sars-cov-2, this"
11440,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.137254902,"on, binding, that, is, most, likely, of"
11441,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.137254902,"that, sars-cov-2, to, a, on, the, of"
11442,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.137254902,"the, of, for, it, is, to, that"
11443,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.137254902,"to, the, that, sars-cov-2, result, of, natural"
11444,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.137254902,"rbd, of, sars-cov-2, to, ace2, the, in"
11445,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.137254902,"the, presence, of, that, sars-cov-2, jumped, in"
11446,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.137254902,"that, the, plausible, scenario, of, and, is"
11447,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.137254902,"the, of, that, sars-cov-2, is, type, in"
11448,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.137254902,"that, the, of, bat, covid-19, closely, a"
11449,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.137254902,"in, the, of, more, than, to, and"
11450,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.137254902,"the, of, from, as, intermediate, hosts, for"
11451,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.137254902,"to, the, in, and, that, bats, hosts"
11452,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.137254902,"the, of, that, was, to, bat, and"
11453,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.137254902,"direct, from, bats, to, humans, is, the"
11454,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.137254902,"previous, the, and, palm, civet, intermediate, host"
11455,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.137254902,"of, are, bats, and, can, be, to"
11456,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.137254902,"the, sars-cov-2, from, pangolins, in, of, is"
11457,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.137254902,"have, the, in, bats, and, from, china"
11458,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.137254902,"also, a, which, is, the, for, to"
11459,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.137254902,"infected, bat, to, a, as, civets, from, the, by, identified, of, and, bats,, species"
11460,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.137254902,"a, data, that, evolved, directly, from, in"
11461,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.137254902,"in, it, not, to, that, sars-cov-2, a"
11462,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.137254902,"that, a, the, of, sars-cov-2, he, but"
11463,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.137254902,"suggest, that, a, of, virus, and, the"
11464,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.137254902,"the, hypothesis, that, sars-cov-2, as, of, natural"
11465,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.137254902,"the, is, to, of, and, has, been"
11466,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.137254902,"the, is, of, natural, sars-cov-2, to, in"
11467,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.137254902,"to, is, be, that, from, and, the"
11468,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.137254902,"coronaviruses, to, the, be, natural, of, with"
11469,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.137254902,"in, also, the, of, sars-cov-2, animals, to"
11470,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.137254902,"to, sars-cov-2, in, the, rbd, ace2, of"
11471,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.137254902,"the, and, that, of, scenario, is, plausible"
11472,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.137254902,"to, the, sars-cov-2, cluster, also, from, and"
11473,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.137254902,"sars-cov-2, a, that, the, as, hosts, for"
11474,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.137254902,"to, the, of, and, which, bat, virus"
11475,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.137254902,"that, with, pangolins, are, hosts, for, sars-cov-2"
11476,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.137254902,"to, the, of, sars-cov-2, intermediate, hosts, for"
11477,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.137254902,"that, pangolins, hosts, for, sars-cov-2, are, with"
11478,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.137254902,"of, the, and, that, sars-cov-2, a, with"
11479,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.137254902,"that, the, in, bats, and, to, hosts"
11480,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.137254902,"of, the, novel, coronavirus, viruses, that, bats"
11481,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.137254902,"the, sarbecovirus, and, are, to, sars-, cov-2"
11482,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.137254902,"the, between, and, of, genome, virus, bat"
11483,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.137254902,"the, of, sars-cov-2, to, on, a, that"
11484,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.137254902,"genome, a, sars-cov-2, with, the, of, bat"
11485,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.137254902,"a, cluster, of, sars-cov-2, to, with, that"
11486,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.137254902,"a, for, the, sars-cov, reservoir, of, and"
11487,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.137254902,"of, that, the, sars-cov-2,, directly, from, bats"
11488,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.137254902,"has, a, sars-cov-2, the, of, virus, in"
11489,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.137254902,"sars-cov-2, the, in, that, type, of, is"
11490,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.137254902,"of, that, sars-cov-2, to, a, cluster, with"
11491,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.137254902,"has, that, the, of, coronaviruses, are, bat"
11492,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.137254902,"suggests, that, is, a, sars-cov-2, analysis, the"
11493,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.136986301,"available, that, sars-cov-2, has, a, origin, and, not, or, constructed"
11494,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.136986301,"in, the, a, coronavirus, that, are, to, and, with, for"
11495,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.136986301,"are, a, for, coronavirus, the, and, in, with, that, to"
11496,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.136986301,"sars-cov-2, origin, has, a, or, available, that, not, constructed, and"
11497,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.136986301,"that, from, bats, to, is, a, coronavirus, in, sars-cov-2, species"
11498,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.136986301,"for, the, of, and, were, host, from, a, with, as"
11499,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.136986301,"sars-cov-2, is, a, from, species, to, that, coronavirus, in, bats"
11500,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.136986301,"and, at, the, huanan, seafood, was, of, from, a, by"
11501,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.136986301,"with, the, of, were, as, a, host, for, from, and"
11502,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.136986301,"the, by, was, from, a, at, huanan, seafood, and, of"
11503,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.136986301,"the, of, that, sars-cov-2, genomes, are, more, to, with, than"
11504,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.136986301,"with, the, by, and, to, that, sars-cov-2, of, pangolin, are"
11505,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.136986301,"that, by, of, pangolin, with, to, and, are, the, sars-cov-2"
11506,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.136986301,"that, are, more, than, the, sars-cov-2, genomes, to, with, of"
11507,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.136363636,"a, viruses, are, to, bat, sars-cov-2"
11508,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.136363636,"a, to, which, many, bat, and"
11509,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.136363636,"the, of, into, humans, from, natural"
11510,"unnatural origin of SARS-CoV-2, but these people are 

simply wrong","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.136363636,"of, but, are"
11511,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.136363636,"and, of, to, animal, species, be"
11512,"According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.136363636,"to, sars-cov, bat"
11513,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.136363636,"in, of, and, china,, which, to"
11514,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.136363636,"virus, its, in"
11515,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.136363636,"the, in, china"
11516,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.136363636,"the, genetic, that, from, any, used"
11517,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.136363636,"and, a, of, sars-cov-2, in, domain,, which, an, the, for, to, human"
11518,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.136363636,"in, the, of, is, to, sars-cov-2, human, and, a"
11519,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.136363636,"the, that, is, in, any, sars-cov-2"
11520,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.136363636,"is, within, with, sars-cov-2, thus, that"
11521,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.136363636,"that, are, to, and, the, of"
11522,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.136363636,"sars-cov-2, natural, that, with, to, the"
11523,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.136363636,"the, of, that, to, it, is"
11524,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.136363636,"the, sars-cov-2, to, of, is, found"
11525,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.136363636,"bat, to, is, sars-cov-2, the, genome"
11526,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.136363636,"sars-cov, it, to, was, the, of, that, sars-cov-2, a"
11527,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.136363636,"of, as, natural, host, genome, and"
11528,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.136363636,"a, of, cov-like, and, are, the"
11529,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.136363636,"to, that, sars-cov-2, the, and, virus"
11530,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.136363636,"of, the, sars-cov-2, in, is, and"
11531,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.136363636,"are, of, sars-cov-2"
11532,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.136363636,"viruses, more, the, reservoirs, than, other"
11533,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.136363636,"the, ability, of, to, be, is, also, for, and"
11534,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.136363636,"also, that, with, the, of, to, as, an, host"
11535,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.136363636,"the, closest, to, was, in, a"
11536,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.136363636,"the, and, that, virus, a, sequence, in, human, to"
11537,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.136363636,"the, as, to, spillover, from, humans"
11538,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.136363636,"the, of, has, history, as, and"
11539,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.136363636,"that, the, of, is, to, it"
11540,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.136363636,"the, animal, in, market, infected, to"
11541,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.136363636,"to, a, in, and, were, animal"
11542,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.136363636,"the, a, spillover, to, of, and"
11543,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.136363636,"is, to, the, an, and, be"
11544,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.136363636,"a, of, sars-cov-2, to, be, coronavirus"
11545,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.136363636,"and, the, of, that, by, evolutionary"
11546,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.136363636,"in, animals, to, the, and, was"
11547,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.136363636,"the, of, to, that, and, sars-cov-2"
11548,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","civet cats and raccoon dogs  

are the intermediate hosts",0.136363636,"are, the, and"
11549,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.136363636,"was, from, that, are, to, and"
11550,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.136363636,"to, can, be, of, and, bats"
11551,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.136363636,"of, to, and, are, the, sars-cov-2"
11552,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","with the first case being linked to  

a seafood market",0.136363636,"a, the, with"
11553,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","with the first case being linked to  

a seafood market",0.136363636,"the, a, to"
11554,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.136363636,"found, the, of, sars-cov-2, is, to"
11555,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.136363636,"that, by, a, one, and, the"
11556,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.136363636,"the, who, that, had, been, virus"
11557,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.136363636,"been, sars-cov-2, in, several, animal, species"
11558,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.136363636,"from, of, natural, the, into, humans"
11559,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.136363636,"to, that, sars-cov-2, the, origin, of"
11560,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.136363636,"evidence, that, the, of, to, as"
11561,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.136363636,"at, bat, that, the, of, from"
11562,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.136363636,"the, of, from, that, was, at"
11563,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.136363636,"the, that, sars-cov-2"
11564,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.136363636,"from, with, sars-cov-2"
11565,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.136363636,"sars-cov-2, are, to, bat, a, viruses"
11566,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.136363636,"that, from, the, bat, at, of"
11567,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.136363636,"to, sars-cov-2, a, that, from, the"
11568,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.136363636,"the, that, to, a, of, mutations"
11569,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.136363636,"the, of, from, two, and, which, were, in, sars-cov-2"
11570,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.136363636,"at, are, a, zoonotic, and, this, in, the, that"
11571,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.136363636,"the, of, at, this, that, sars-cov-2, a, circulating, in"
11572,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.136363636,"sars-cov-2, into, humans, the, most, for"
11573,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.136363636,"that, of, sars-cov-2, the, huanan, animals"
11574,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.136363636,"to, that, sars-cov-2, the, be, of"
11575,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.136363636,"in, the, case, of, and, market"
11576,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.136363636,"the, reservoirs, more, viruses, than, other"
11577,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.136363636,"that, the, in, and, huanan, market"
11578,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.136363636,"to, a, spillover, of, and, the"
11579,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.136363636,"the, that, to, of, and, re-"
11580,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.136363636,"the, of, that, more, to, than"
11581,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.136363636,"sars-cov-2, may, from, a, that, in"
11582,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.136363636,"the, of, evidence, at, this, that, is, a, has, been, animal, for"
11583,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.136363636,"to, the, from, as, spillover, humans"
11584,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.136363636,"the, genetic, in, from, market, that"
11585,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.136363636,"the, to, covid-19, for, a, from, wild, is, likely"
11586,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.136363636,"bat, coronavirus, to, as, similarity, the"
11587,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.136363636,"that, the, virus, and, from, animals"
11588,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.136363636,"the, taken, from, huanan, seafood, and"
11589,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.136363636,"the, of, as, intermediate, was, to"
11590,"with the first case being linked to  

a seafood market","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.136363636,"with, the, a"
11591,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.136363636,"the, huanan, market, that, in, and"
11592,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.136363636,"the, were, to, that, in, and"
11593,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.136363636,"a, of, the, that, cases, were, and, with, huanan"
11594,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.136363636,"who, that, the, virus, had, been"
11595,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.136363636,"who, the, to, that, virus, in"
11596,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.136363636,"the, covid-19, cases, huanan, market, of"
11597,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.136363636,"an, from, of, to, and, the"
11598,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.136363636,"the, of, an, to, that, virus"
11599,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.136363636,"a, to, that, the, sars-cov-2, from"
11600,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.136363636,"from, bats, to, sars-cov-2, and, the"
11601,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.136363636,"is, that, a, sars-cov-2, humans,, the"
11602,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.136363636,"the, to, that, sars-cov-2, was, virus"
11603,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.136363636,"and, that, a, the, virus, is"
11604,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.136363636,"the, using, and, to, that, sars-cov-2, is, pangolin, as"
11605,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.136363636,"that, the, sars-cov-2, and, pangolin, is"
11606,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.136363636,"and, from, to, be, that, the, is, bats, sars-cov-2"
11607,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.136363636,"has, that, the, of, from, bat"
11608,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.136363636,"that, has, to, and, with, respectively"
11609,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","Bats have been reported as being the rich source of 

coronaviruses",0.136363636,"the, of, been"
11610,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.136363636,"with, sars-cov-2, from"
11611,"a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.136363636,"coronavirus, with, sars-cov-2"
11612,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.136363636,"the, sars-cov-2, bat"
11613,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.136363636,"virus, the, to, and, that, sars-cov-2"
11614,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.136363636,"the, of, sars-cov-2, to, and, by"
11615,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.136363636,"the, of, a, and, sars-cov-2, recombination"
11616,"According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.136363636,"to, is, bat"
11617,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.136363636,"the, of, is, to, human, and"
11618,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.136363636,"sars-cov-2, was, and, to, the, of"
11619,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.136363636,"have, shown, that, the, of, to"
11620,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.136363636,"from, in, china, the, virus, and"
11621,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.136363636,"that, from, the, and, animals, virus"
11622,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.136363636,"the, was, in, and, to, animals"
11623,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.136363636,"are, in, animals, and, transmitted, to"
11624,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.136363636,"covid-19, has, in"
11625,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.136363636,"that, the, were, in, to, and"
11626,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.136363636,"to, the, who, in, that, virus"
11627,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.136363636,"natural, virus, that, humans, to, the"
11628,"According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.136363636,"to, sars-cov, is"
11629,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.136363636,"the, and, in, is, similar, to"
11630,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.136363636,"sequence, identity, and, the, of, virus"
11631,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.136363636,"is, to, the, that, and, be"
11632,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.136363636,"of, to, be, that, zoonotic, may"
11633,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.136363636,"the, host, of"
11634,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.136363636,"the, bats, to, reservoir, sars-cov-2, bat"
11635,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.136363636,"the, viruses,, related, to, is, bat"
11636,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.136363636,"genomic, analysis, that, the, bats, to"
11637,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.136363636,"but, be, possible, a, bat, not, only, bats, of"
11638,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.136363636,"to, sars-cov-2, the"
11639,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.136363636,"is, that, a, host, sars-cov-2, to"
11640,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.136363636,"of, the, coronavirus, is, similar, to"
11641,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.136363636,"coronavirus, the, genome, similar, to, of"
11642,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.136363636,"the, of, to, human, than, sars-cov-2."
11643,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.136363636,"bat, to, sars-cov"
11644,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.136363636,"is, to, bat"
11645,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.136363636,"is, to, sars-cov"
11646,"S1/S2 cleavage sites of coronaviruses are frequently modi- 

fied by insertions or deletions (indels) during evolution","Coronaviruses are naturally hosted and developmentally 

formed by bats.",0.136363636,"coronaviruses, are, by"
11647,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.136363636,"the, has, of, that, from, bat"
11648,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.136363636,"that, and, the, virus, new, of"
11649,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.136363636,"shown, to, sars-cov-2"
11650,"genetic sequencing has been used to show that  

COVID-19 exists in bats,",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.136363636,"has, covid-19, in"
11651,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.136363636,"the, covid-19, in"
11652,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",Many of these CoVs can infect several animal species as well,0.136363636,"as, animal, of"
11653,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",Many of these CoVs can infect several animal species as well,0.136363636,"several, animal, species"
11654,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.136363636,"human, virus, zoonotic"
11655,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.136363636,"that, is, to"
11656,"expended to make the simple point 

that COVID-19 had a natural origin.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.136363636,"to, that, a"
11657,Bats are hosts of many coronaviruses,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.136363636,"bats, are, coronaviruses"
11658,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.136363636,"the, infected, to, animal, market, in"
11659,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.136363636,"from, into, and, to, the, may, have, been, in"
11660,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.136363636,"all, sars-cov-2, and, not, that, is"
11661,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.136363636,"virus, in, its"
11662,"this one jumped from bats origin  

into humans","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.136363636,"jumped, from, humans"
11663,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.136363636,"of, and, species, to, be, animal"
11664,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.136363636,"of, the, virus, bat, sars-like, and"
11665,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.136363636,"the, bat, coronavirus, closest, sequence, of"
11666,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.136363636,"genome, with, the, of, virus, from"
11667,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.136363636,"the, of, coronavirus, is, similar, to"
11668,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.136363636,"is, similar, sars-cov-2, the, sequence, of"
11669,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.136363636,"to, of, is, highly, that, similar"
11670,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.136363636,"as, the, of, sars, and, mers"
11671,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.136363636,"analysis, that, the, originated, and, through"
11672,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.136363636,"et, a, sars-cov-2, by, genome, the"
11673,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.136363636,"sars-cov-2, protein, to, human, ace2, or"
11674,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.136363636,"in, the, a, outbreak, that, from, humans, to, and"
11675,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.136363636,"from, with, genome, the, of, virus"
11676,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.136363636,"from, in, that, a, sars-cov-2, may"
11677,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.136363636,"that, is, sars-cov-2"
11678,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.136363636,"that, sars-cov-2, is"
11679,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.136363636,"the, of, and, hosts, are, sars-cov-2"
11680,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.136363636,"the, huanan, animals, that, sars-cov-2, of"
11681,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Bats are natural hosts of many of the known  

coronaviruses",0.136363636,"of, the, natural"
11682,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.136363636,"the, intermediate, was, to, of, as"
11683,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.136363636,"is, the, most"
11684,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.136363636,"a, mutations, to, that, the, of"
11685,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.136363636,"of, the, to, and, re-, that"
11686,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.136363636,"a, that, the, to, infect, and"
11687,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.136363636,"it, is, that, a, of, the"
11688,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.136363636,"the, of, to, that, virus, humans."
11689,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.136363636,"that, the, in, to, at, a"
11690,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.136363636,"the, genome, of, coronavirus, similar, to"
11691,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.136363636,"in, similar, at, with, the, of"
11692,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.136363636,"are, to, and"
11693,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.136363636,"to, are, and"
11694,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.136363636,"the, of, and, sars-cov-2, was, to"
11695,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.136363636,"the, sequenced, was, and, to, of"
11696,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.136363636,"a, the, closest, to, in, was"
11697,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.136363636,"to, the, of, yunnan, a, bat"
11698,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.136363636,"closest, to, of, from, a, sars-cov-2"
11699,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.136363636,"a, the, sars-cov-2, genome,, in, bat"
11700,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.136363636,"the, sars-cov-2, closest, of, genome,, to"
11701,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.136363636,"the, of, to, sars-cov-2, was, from"
11702,"Bats have been reported as being the rich source of 

coronaviruses","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.136363636,"been, the, of"
11703,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.136363636,"analysis, of, the, sequence, that, sars-cov-2"
11704,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.136363636,"sars-cov-2, of, the, similar, to, in, virus, analysis, rbd"
11705,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","this one jumped from bats origin  

into humans",0.136363636,"jumped, humans, from"
11706,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.136363636,"virus, human, zoonotic"
11707,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.136363636,"a, and, of, in, the, western"
11708,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.136363636,"the, of, sars-cov-2, to, for, and"
11709,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.136363636,"viruses, of, the, sars-cov-2, in, and"
11710,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.136363636,"genome, and, as, natural, host, of"
11711,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.136363636,"two, from, the, and, with, sars-cov-"
11712,"a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.136363636,"a, similarity, sars-cov-2"
11713,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.136363636,"sars-cov-2, genome, to"
11714,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.136363636,"the, to, of, a, bat, yunnan"
11715,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.136363636,"is, that, sars-cov-2, the, in, any"
11716,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.136363636,"the, sars-cov-2, and, to, a, of, is, in, human"
11717,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.136363636,"the, is, to, of, and, human"
11718,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.136363636,"of, the, from, sars-cov-2, and, two, in, which, were"
11719,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.136363636,"sars-cov-2, genome, sequences, and, the, of"
11720,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.136363636,"sars-cov-2, a, similarity"
11721,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.136363636,"that, sars-cov-2, the"
11722,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.136363636,"sars-cov-2, that, is"
11723,"This suggests that the BANAL series may be able to directly infect  

humans.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.136363636,"that, the, to"
11724,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.136363636,"sars-cov-2, that, to"
11725,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.136363636,"that, the, sars-cov-2, same, and, is"
11726,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.136363636,"the, analysis, of, sequence, that, sars-cov-2"
11727,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.136363636,"in, to, the, of, sars-cov-2, has"
11728,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.136363636,"the, an, to, of, and, from"
11729,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.136363636,"to, sars-cov-2, from, bats, and, the"
11730,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.136363636,"with, the, sars-cov-, two, from, and"
11731,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.136363636,"the, is, similar, to, and, in"
11732,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.136363636,"the, that, also, with, of, sars-cov-2, or, as, for"
11733,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.136363636,"that, the, of, and, may, as, hosts, for, sars-cov-2"
11734,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.136363636,"the, that, to, infect, a, and"
11735,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.136363636,"also, for, the, of, is, and, be, ability, to"
11736,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.136363636,"of, to, sars-cov-2, by, the, and"
11737,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.136363636,"sars-cov-2, to, the, for, and, of"
11738,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.136363636,"it, be, the, between, and, of"
11739,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.136363636,"sars-cov-2, and, some, to, the, of"
11740,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.136363636,"was, that, the, of, to, a"
11741,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.136363636,"a, the, to, that, and, was"
11742,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.136363636,"and, were, to, in, the, market."
11743,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.136363636,"that, from, the, was, at, of"
11744,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.136363636,"genetic, the, that, in, from, market"
11745,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.136363636,"in, the, that, sars-cov-2, from, for"
11746,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.136363636,"is, a, progenitor, of, sars-cov-2, the"
11747,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.136363636,"the, in, of, to, sars-cov-2, virus"
11748,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.136363636,"a, natural, of, the, virus, is"
11749,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.136363636,"in, to, closely, related, the, of, is, natural, sars-cov-2"
11750,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.136363636,"the, of, more, and, in, bats"
11751,Many of these CoVs can infect several animal species as well,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.136363636,"of, animal, as"
11752,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.136363636,"the, of, as, and, sars, mers"
11753,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.136363636,"sars-cov-2, to, bat, bats, the, reservoir"
11754,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.136363636,"the, bats, and, to, intermediate, of"
11755,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.136363636,"the, of, sars-cov-2, and, likely, bats"
11756,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.136363636,"and, the, southeast, asia,, in, china"
11757,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.136363636,"of, and, bat, species, in, the"
11758,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.136363636,"bat, and, species, in, the, of"
11759,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.136363636,"in, a, of, to, sars-related, the, bats, which, for, different, this, bat, and, viruses, closely, related, other, virus"
11760,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.136363636,"to, and, migration, of, is, that, similar, viruses, related, in, bat, populations"
11761,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.136363636,"closest, to, sars-cov-2, from, of, a"
11762,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.136363636,"the, genome, sars-cov-2, is, to, bat"
11763,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.136363636,"the, as, coronavirus, bat, similarity, to"
11764,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.136363636,"the, similarity, to, bat, is, as"
11765,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.136363636,"the, sars-cov-2, closest, at, similarity, to"
11766,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.136363636,"the, of, sars-cov-2, closely, related, to"
11767,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.136363636,"the, and, of, is, to, that"
11768,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.136363636,"the, of, that, to, rbd, similar"
11769,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.136363636,"the, of, have, shown, that, to"
11770,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.136363636,"the, of, than, to, human, sars-cov-2."
11771,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.136363636,"were, to, a, and, animal, in"
11772,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.136363636,"is, related, to, bat, viruses,, the"
11773,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.136363636,"covid-19, that, it, is, the, and"
11774,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.136363636,"that, the, of, cases, were, with, a, and, huanan"
11775,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.136363636,"taken, from, the, huanan, seafood, and"
11776,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.136363636,"was, sequenced, and, to, the, of"
11777,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.136363636,"a, the, to, that, in, sequence, human, virus, and"
11778,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.136363636,"in, the, same, of, a, to, study, as, by, taken, samples, with, found, 15, these, sars,, were, and, that, sars, from, it, 14, reservoir"
11779,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.136363636,"that, the, outbreak, from, a, in, to, humans, and"
11780,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.136363636,"and, the, of, bat, to, sars-related, viruses, a, closely, related, bats, different, other, this, in, for, which, virus"
11781,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.136363636,"as, a, of, the, and, these, were, by, in, to, sars, it, with, samples, study, found, that, taken, from, 14, 15, same, sars,, reservoir"
11782,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.136363636,"the, of, a, and, in, western"
11783,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.136363636,"to, were, and, in, the, market."
11784,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.136363636,"of, covid-19, cases, the, huanan, market"
11785,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.136363636,"to, and, a, the, origin, of"
11786,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.136363636,"a, the, this, that, and, are, at, zoonotic, in"
11787,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.136363636,"a, that, the, to, and, sars"
11788,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.136363636,"that, are, to, and, a, the"
11789,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.136363636,"that, sars-cov-2, to, with, the, natural"
11790,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.136363636,"the, most, for, sars-cov-2, into, humans"
11791,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.136363636,"the, natural, to, that, virus, humans"
11792,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.136363636,"that, the, for, sars-cov-2, on, its"
11793,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","expended to make the simple point 

that COVID-19 had a natural origin.",0.136363636,"that, to, a"
11794,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","unnatural origin of SARS-CoV-2, but these people are 

simply wrong",0.136363636,"are, but, of"
11795,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","unnatural origin of SARS-CoV-2, but these people are 

simply wrong",0.136363636,"are, origin, of"
11796,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.136363636,"that, in, bats, and, to, china,"
11797,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.136363636,"viruses, of, the, in, their, and"
11798,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.136363636,"the, sars-cov-2, genome,, in, a, bat"
11799,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.136363636,"shows, 96.2%, a, sequence, bat, in"
11800,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.136363636,"sars-cov-2, to, human, ace2, protein, or"
11801,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.136363636,"is, that, or, of, the, natural"
11802,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.136363636,"that, the, is, sars-cov-2, a, or"
11803,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.136363636,"the, genetic, any, that, used, from"
11804,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.136363636,"bat, to, as, similarity, is, the"
11805,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.136363636,"its, reservoir, as, it, to, for, the, of, that"
11806,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.136363636,"that, and, the, of, by, evolutionary"
11807,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.136363636,"sars-cov-2, is, a, that, humans,, the"
11808,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.136363636,"the, is, that, a, of, it"
11809,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.136363636,"the, is, of, sars-cov-2, a, progenitor"
11810,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.136363636,"the, virus, an, to, that, of"
11811,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.136363636,"to, sars-cov-2, virus, that, was, the"
11812,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.136363636,"the, that, virus, to, of, humans."
11813,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.136363636,"the, of, sars-cov-2, to, virus, in"
11814,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.136363636,"a, of, sars-cov-2, the, recombination, and"
11815,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.136363636,"all, that, sars-cov-2, and, is, not"
11816,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","In the 

case of MERS, dromedaries were the principal host.",0.136363636,"the, were, in"
11817,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.136363636,"that, not, a, bat, to, first"
11818,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.136363636,"the, more, of, bats, in, and"
11819,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",The COVID-19 most likely developed from bat origin coronaviruses,0.136363636,"the, most, from"
11820,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.136363636,"is, that, or, species, of, the"
11821,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.136363636,"genomic, analysis, that, to, bats, the"
11822,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.136363636,"the, analysis, that, originated, through, and"
11823,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.136363636,"the, bats, to, of, intermediate, and"
11824,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.136363636,"that, to, in, bats, china,, and"
11825,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.136363636,"intermediate, bats, and, humans, in, the"
11826,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.136363636,"that, the, of, and, suggests, bats"
11827,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.136363636,"are, in, animals, to, and, transmitted"
11828,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",Bats are hosts of many coronaviruses,0.136363636,"bats, of, are"
11829,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",Bats are hosts of many coronaviruses,0.136363636,"are, coronaviruses, bats"
11830,"This suggests that the BANAL series may be able to directly infect  

humans.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.136363636,"the, be, to"
11831,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.136363636,"the, to, in"
11832,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.136363636,"have, been, by, in, the, of"
11833,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.136363636,"it, is, that, the, covid-19, and"
11834,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.136363636,"that, be, they, animals, in, with"
11835,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.136363636,"of, was, to, the, in, animals"
11836,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.136363636,"the, of, is, natural, or, that"
11837,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.136363636,"of, that, the, is, species, or"
11838,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.136363636,"of, bats, and, can, be, to"
11839,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.136363636,"the, in, bats, and, humans, intermediate"
11840,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.136363636,"a, of, be, possible, bat, not, but, only, bats"
11841,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.136363636,"the, of, case, and, market, in"
11842,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.136363636,"the, and, sars-cov-2, is, in, of"
11843,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.136363636,"of, viruses, in, their, and, the"
11844,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.136363636,"of, the, sequence, sars-cov-2, is, similar"
11845,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.136363636,"in, the, with, similar, of, at"
11846,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.136363636,"in, similar, of, sars-cov-2, the, protein"
11847,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.136363636,"the, in, china, and, southeast, asia,"
11848,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.136363636,"a, to, the, likely, covid-19, is, from, wild, for"
11849,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.136363636,"that, sars-cov-2, and, bat, cov, share"
11850,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.136363636,"that, sars-cov-2, genome, cov, and, a"
11851,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.136363636,"first, to, bat, that, a, not"
11852,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.136363636,"from, intermediate, it, to, not, that, sars-cov-2, in, a"
11853,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.136363636,"from, that, sars-cov-2, to, a, bat"
11854,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.136363636,"a, that, sars-cov-2, to, host, is"
11855,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.136363636,"was, that, the, of, sars-cov-2, to, a, it, sars-cov"
11856,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.136363636,"the, have, been, into, from, in, to, and, may"
11857,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.136363636,"the, of, to, it, that, as, reservoir, for, its"
11858,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.136363636,"that, sars-cov-2, not, from, a, to, it, in, intermediate"
11859,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.136363636,"the, of, to, that, sars-cov-2, was, not, from, humans."
11860,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.136363636,"the, was, of"
11861,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.136363636,"of, the, sars-cov-2"
11862,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.136363636,"sars-cov-2, been, animal, several, in, species"
11863,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.136363636,"sars-cov-2, was, the"
11864,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.136363636,"the, bat, sars-cov-2"
11865,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.136363636,"the, bat, cov"
11866,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.136363636,"the, virus, is, that, of, and"
11867,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.136363636,"is, a, virus, that, and, the"
11868,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.136363636,"the, is, of, natural, a, virus"
11869,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.136363636,"the, of, that, is, a, virus"
11870,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",Genetic evidence suggesting otherwise is yet to be presented.,0.136363636,"to, is, be"
11871,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.136363636,"sars-cov-2, also, of, that, the, with, as, or, for"
11872,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.136363636,"has, the, history, of, as, and"
11873,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.136363636,"has, the, of, to, sars-cov-2, in"
11874,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.136363636,"of, the, have, been, in, by"
11875,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.136363636,"was, that, are, from, to, and"
11876,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.136363636,"and, are, to"
11877,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.136363636,"that, to, sars-cov-2"
11878,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.136363636,"is, to, be, an, and, the"
11879,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.136363636,"is, that, the, and, be, to"
11880,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.136363636,"the, sars-cov-2, to, be, with, appears, consistent, of, natural"
11881,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.136363636,"the, was, to, in, of, animals"
11882,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.136363636,"the, of, sars-cov-2, with, appears, to, be, consistent, natural"
11883,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.136363636,"the, and, us, to, that, is, of, sars-, cov-2"
11884,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.136363636,"that, to, and, the, origin, of"
11885,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.136363636,"and, to, be, that, the, of, sars-, is, natural"
11886,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.136363636,"sars-cov-2, that, its, on, the, for"
11887,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.136363636,"the, sars-cov-2, is, to, that, bat"
11888,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.136363636,"a, is, to, the, that, it"
11889,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.136363636,"and, to, bat, a, which, many"
11890,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.136363636,"to, a, virus, that, and, the"
11891,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.136363636,"of, the, virus, and, bat, sars-like"
11892,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.136363636,"a, and, the, that, to, sars"
11893,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.136363636,"the, of, that, to, a, bat"
11894,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.136363636,"the, genome, by, et, sars-cov-2, a"
11895,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.136363636,"a, sequence, shows, 96.2%, in, bat"
11896,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.136363636,"sars-cov-2, of, domain,, which, for, to, human, a, in, an, and, the"
11897,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.136363636,"and, in, china,, to, of, which"
11898,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.136363636,"that, be, in, animals, with, they"
11899,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.136363636,"are, the, of, a, and, cov-like"
11900,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.136363636,"the, and, by, a, one, that"
11901,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.136363636,"the, of, that, sars-cov-2, a, in"
11902,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.136363636,"sars-cov-2, is, to"
11903,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.136363636,"sars-cov-2, with, within, is, thus, that"
11904,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.136363636,"the, bats, likely, of, sars-cov-2, and"
11905,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.136363636,"suggests, that, the, bats, and, of"
11906,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.136363636,"that, sars-cov-2, has, the, of, and"
11907,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.136363636,"ratg13, is, the, bat, to, in"
11908,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.136363636,"to, sars-cov-2, is, that, and, using, the, pangolin, as"
11909,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.136363636,"us, to, that, the, of, sars-, cov-2, and, is"
11910,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.136363636,"the, probable, of"
11911,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.136363636,"the, this, that, sars-cov-2, in, for"
11912,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.136363636,"sars-cov-2, is, that, and, the, pangolin"
11913,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.136363636,"bat, cov, that, and, sars-cov-2, share"
11914,"unnatural origin of SARS-CoV-2, but these people are 

simply wrong","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.136363636,"origin, of, are"
11915,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.136363636,"this, the, sars-cov-2"
11916,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.136363636,"sars-cov-2, may, of, and, that, the, as, hosts, for"
11917,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.136363636,"and, the, virus, from, in, china"
11918,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.136363636,"the, sequences, of, and, sars-cov-2, genome"
11919,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.136363636,"the, and, of, a, origin, to"
11920,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.136363636,"are, a, and, the, that, to"
11921,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.136363636,"genome, cov, that, and, sars-cov-2, a"
11922,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.136363636,"to, that, the, of, origin, and"
11923,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.136363636,"more, than, of, the, to, that"
11924,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.136363636,"ratg13, the, bat, to, of, than"
11925,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.136363636,"has, to, with, that, and, respectively"
11926,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.136363636,"the, and, of, new, virus, that"
11927,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.136363636,"the, closest, to, sars-cov-2, genome,, of"
11928,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.136363636,"closest, to, similarity, sars-cov-2, at, the"
11929,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.136363636,"the, of, be, it, and, between"
11930,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.136363636,"the, this, it, that, in, of"
11931,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.136363636,"the, sars-cov-2, to, from, bats, of"
11932,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.136363636,"the, to, sars-cov-2, was, from, of"
11933,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.136363636,"from, to, humans., was, not, the, of, that, sars-cov-2"
11934,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.136363636,"of, virus, that, is, to, the"
11935,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.136363636,"to, the, that, sars-cov-2, of, origin"
11936,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.136363636,"the, that, to, be, sars-cov-2, of"
11937,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.136363636,"most, that, the, of, sars-cov-2, is"
11938,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.136363636,"the, is, most"
11939,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.136363636,"a, of, the, this, that, sars-cov-2, at, in, circulating"
11940,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.136363636,"that, this, at, the, animal, a, of, is, has, been, evidence, for"
11941,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.136363636,"of, the, in, that, sars-cov-2, a"
11942,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.136363636,"this, the, in, that, for, sars-cov-2"
11943,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.136363636,"from, the, that, in, for, sars-cov-2"
11944,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.136363636,"sars-cov-2, to, be, a, of, coronavirus"
11945,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.136363636,"that, zoonotic, may, be, of, to"
11946,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.136363636,"the, of, that, sars-cov-2, was, to"
11947,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.136363636,"in, similar, sars-cov-2, the, of, protein"
11948,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.136363636,"to, of, that, similar, rmyn02, in"
11949,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.136363636,"to, sars-cov-2, is, be, that, from, bats, and, the"
11950,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.136363636,"the, is, of, natural, sars-cov-2, to, closely, related, in"
11951,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.136363636,"to, that, natural, the, of, sars-, and, is, be"
11952,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.136363636,"of, the, sequence, closest, bat, coronavirus"
11953,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.136363636,"is, to, in, the, bat, ratg13"
11954,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.136363636,"the, of, to, bat, ratg13, than"
11955,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.136363636,"of, that, is, highly, similar, to"
11956,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.136363636,"and, migration, of, bat, populations, to, similar, viruses, related, that, in, is"
11957,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.136363636,"rmyn02, in, similar, to, that, of"
11958,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.136363636,"also, as, the, of, with, that, to, an, host"
11959,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.136363636,"evidence, to, the, that, as, of"
11960,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.136363636,"in, the, analysis, of, sars-cov-2, to, rbd, similar, virus"
11961,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.136363636,"the, of, sars-cov-2, to, and, some"
11962,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.136363636,"the, sars-cov-2, is, a, or, that"
11963,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.136054422,"in, the, of, a, to, bat, cave, as, with, viruses, sars-related, moreover,, similar, and, that, recombination, events, this, specific, its"
11964,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.136054422,"and, the, of, bat, to, specific, similar, sars-related, viruses, as, a, moreover,, cave, with, that, this, in, recombination, events, its"
11965,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.13592233,"a, by, was, market, in, that, the, virus, is, to, group, of, were, bats"
11966,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.13592233,"the, to, in, a, of, group, is, was, that, bats, virus, were, by, market"
11967,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.135802469,"into, the, wiv, that, is, not, in, any, related, to, sars-cov-2"
11968,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.135802469,"the, of, and, intermediate, palm, a, human, or, with, as, to"
11969,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.135802469,"the, that, wiv, to, related, in, is, not, into, sars-cov-2, any"
11970,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.135802469,"that, more, than, the, sars-cov-2, to, with, in, this, of, and"
11971,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.135802469,"to, in, for, the, virus, southern, china, sars, were, and, other"
11972,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.135802469,"are, more, than, the, sars-cov-2, to, these, may, with, in, and"
11973,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.135802469,"and, a, to, the, of, human, with, palm, or, as, intermediate"
11974,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.135802469,"the, virus, for, sars, and, other, to, were, in, southern, china"
11975,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.135802469,"from, such, as, and, to, by, the, of, that, been, a"
11976,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.135802469,"the, been, as, a, of, that, from, to, by, such, and"
11977,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.135802469,"in, the, of, more, than, to, that, sars-cov-2, with, and, this"
11978,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.135802469,"are, to, in, may, more, with, sars-cov-2, than, these, the, and"
11979,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.13559322,"sars-cov-2, a, and, coronaviruses, bat, to, which, in"
11980,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.13559322,"in, a, of, being, sars-cov-2, to, infected, with"
11981,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.13559322,"the, sars-cov-2, to, in, of, is, be, found"
11982,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.13559322,"viruses, to, the, of, and, that, these, emergence"
11983,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.13559322,"to, that, the, of, and, have, origin, sars-cov-2"
11984,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.13559322,"a, of, to, that, the, recombination, and, virus"
11985,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.13559322,"that, bats, are, the, for, a, of, and"
11986,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.13559322,"and, to, be, the, of, coronavirus, is, sars-cov-2"
11987,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.13559322,"the, sars-cov-2, to, be, of, is, found, in"
11988,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.13559322,"the, has, been, identified, of, from, to, humans"
11989,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.13559322,"studies, and, have, sars-cov-2, an, animal, transmitted, to"
11990,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.13559322,"genetic, have, in, and, to, from, a, china"
11991,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.13559322,"from, a, to, in, the, suggests, that, may"
11992,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.13559322,"it, was, that, sars-cov-2, and, to, is, used"
11993,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.13559322,"the, and, that, samples, were, huanan, taken, from"
11994,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.13559322,"as, and, the, to, be, that, sars-cov-2, is"
11995,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.13559322,"a, the, recombination, of, virus, and, that, to"
11996,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.13559322,"sars-cov-2, have, transmitted, an, animal, to, studies, and"
11997,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.13559322,"have, from, to, a, genetic, and, in, china"
11998,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.13559322,"sars-cov, had, its, and, to, the, that, in"
11999,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.13559322,"and, to, be, that, the, of, is, bats"
12000,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.13559322,"that, it, was, sars-cov-2, to, and, is, used"
12001,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.13559322,"a, from, seafood, market, in, that, the, to"
12002,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.13559322,"and, sars-cov-2, to, bat, coronaviruses, in, a, which"
12003,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.13559322,"et, al., that, may, of, to, the, intermediate"
12004,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.13559322,"and, a, of, which, the, viruses, to, human"
12005,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.13559322,"sars-cov-2, the, and, in, not, that, of, is"
12006,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.13559322,"is, to, the, that, has, been, and, this"
12007,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.13559322,"in, a, of, for, sars-cov-2, to, with, that"
12008,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.13559322,"the, bats, species, to, of, sars-cov-2, intermediate, malayan"
12009,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.13559322,"that, the, of, sars-cov-2, suggests, coronavirus, from, bats"
12010,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.13559322,"coronaviruses, in, which, of, sars-cov-2, nucleotide, and, sequences"
12011,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.13559322,"to, sars-cov-2, is, be, that, and, the, as"
12012,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.13559322,"therefore,, the, is, result, of, natural, sars-cov-2, to"
12013,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.13559322,"the, of, sars-cov-2, species, may, also, for, and"
12014,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.13559322,"a, in, the, that, sars-cov-2, animal, or, for"
12015,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.13559322,"also, that, with, the, of, may, as, intermediate"
12016,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.13559322,"the, to, have, it, that, has, been, in"
12017,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.13559322,"sars-cov-2, may, also, of, species, and, the, for"
12018,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.13559322,"the, that, sars-cov-2, has, with, of, and, to"
12019,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.13559322,"the, of, to, therefore,, sars-cov-2, is, result, natural"
12020,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.13559322,"of, bats, to, intermediate, malayan, sars-cov-2, species, the"
12021,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.13559322,"the, of, bat, species, in, same, viruses, a"
12022,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.13559322,"of, viruses, bat, a, species, in, the, same"
12023,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.13559322,"the, wiv, for, to, a, sars-related, virus, that, similar, researchers, by, sars, in, 2013,, of, yunnan"
12024,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.13559322,"in, a, sars-cov-2, to, with, events, may, common"
12025,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.13559322,"the, of, by, for, in, 2013,, wiv, researchers, a, virus, similar, to, sars, sars-related, yunnan, that"
12026,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.13559322,"from, its, as, and, to, this, was, for, by, the, of, that, adapted, in, a, infect"
12027,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.13559322,"samples, that, were, taken, from, the, huanan, and"
12028,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.13559322,"is, not, a, on, the, binding, spike, protein"
12029,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.13559322,"from, in, the, suggests, that, a, may, to"
12030,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.13559322,",, to, in, the, rbd,, that, spike, is"
12031,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.13559322,",, is, to, spike, in, the, rbd,, that"
12032,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.13559322,"in, the, of, is, not, that, sars-cov-2, and"
12033,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.13559322,"these, the, evidence, that, or, possible, hosts, for"
12034,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.13559322,"the, viruses, and, of, that, these, to, emergence"
12035,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.13559322,"it, has, been, in, the, to, that, have"
12036,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.13559322,"by, was, in, the, closely, related, found, bats"
12037,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.13559322,"the, identified, has, been, to, humans, from, of"
12038,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.13559322,"the, to, and, sars-cov, that, had, its, in"
12039,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.13559322,"from, the, was, for, to, a, that, this, as, and, infect, by, adapted, in, of, its"
12040,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.13559322,"and, of, sars-cov-2, in, their, is, the, to"
12041,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.13559322,"the, binding, spike, protein, is, on, a, not"
12042,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.13559322,"nucleotide, sequences, of, coronaviruses, and, which, in, sars-cov-2"
12043,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.13559322,"the, is, to, that, has, been, and, this"
12044,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.13559322,"that, the, from, a, seafood, market, in, to"
12045,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.13559322,"bats, was, found, in, by, closely, related, the"
12046,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.13559322,"shows, that, the, at, of, complete, virus, to"
12047,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.13559322,"of, many, and, a, which, to, that, covs"
12048,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.13559322,"the, of, human, to, a, and, which, viruses"
12049,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.13559322,"and, in, their, to, the, of, sars-cov-2, is"
12050,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.13559322,"the, of, et, al., that, may, intermediate, to"
12051,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.13559322,"evidence, that, the, these, possible, hosts, or, for"
12052,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.13559322,"suggests, that, of, from, bats, coronavirus, sars-cov-2, the"
12053,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.13559322,"the, sars-cov-2, cluster, and, this, bat, pangolin, origin"
12054,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.13559322,"that, sars-cov-2, the, with, bat, cov, ratg13, guangdong"
12055,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.13559322,"with, the, that, sars-cov-2, bat, cov, ratg13, guangdong"
12056,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.13559322,"and, sars-cov-2, bat, pangolin, cluster, this, the, origin"
12057,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.13559322,"the, origin, of, to, that, have, and, sars-cov-2"
12058,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.13559322,"bats, are, a, for, the, of, and, that"
12059,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.13559322,"to, sars-cov-2, of, the, and, has, that, with"
12060,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.13559322,"sars-cov-2, in, a, animal, that, the, or, for"
12061,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.13559322,"a, of, in, being, to, infected, with, sars-cov-2"
12062,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.13559322,"in, of, for, to, that, sars-cov-2, with, a"
12063,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.13559322,"a, to, events, common, in, may, with, sars-cov-2"
12064,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.13559322,"of, a, that, to, which, many, covs, and"
12065,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.13559322,"sars-cov-2, is, to, be, of, coronavirus, and, the"
12066,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.13559322,"is, that, the, and, bats, be, of, to"
12067,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.13559322,"may, also, of, that, the, with, as, intermediate"
12068,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.135416667,"the, of, for, 2, it, is, to, that, has, been, human, this, a"
12069,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.135416667,"from, the, was, to, a, bat, in, of, isolated, sample, yunnan, closest, an"
12070,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.135416667,"2, that, it, to, human, this, the, a, of, is, has, been, for"
12071,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.135416667,"to, the, bats, were, several, and, in, of, species, from, an, those, humans"
12072,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.135416667,"in, an, from, species, of, bats, were, to, and, the, several, those, humans"
12073,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.135416667,"the, closest, to, was, isolated, in, from, an, sample, of, a, bat, yunnan"
12074,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.135338346,"the, also, for, to, a, sars-related, virus, that, similar, with, this, bat, as, and, infect, in, of, its"
12075,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.135338346,"and, the, of, bat, also, to, similar, sars-related, as, a, with, infect, that, this, in, for, virus, its"
12076,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.135135135,"sars-cov, in, and, to, other"
12077,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.135135135,"viruses, closely, related, sars-cov-2, in"
12078,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.135135135,"large, number, of, animal, in"
12079,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.135135135,"are, the, from, bats, in"
12080,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.135135135,"the, sars-cov, and, to, sars-like"
12081,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.135135135,"sars-cov-2, is, virus, its, to"
12082,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.135135135,"of, sars-cov-2, been, that, a"
12083,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.135135135,"to, sars-cov-2, a, recombination, of, in, the, and, site, coronaviruses"
12084,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.135135135,"a, sars-cov-2, with, that, and"
12085,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.135135135,"are, the, of, and, viruses"
12086,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.135135135,"a, sars-cov-2, it, the, cov"
12087,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.135135135,"the, of, sars-cov-2, identity, sars-cov"
12088,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.135135135,"and, virus, has, of, bat"
12089,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.135135135,"has, evolutionary, of, virus, and"
12090,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.135135135,"the, viruses, and, are, of"
12091,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.135135135,"the, and, of, a, natural"
12092,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.135135135,"the, natural, reservoir, and, of"
12093,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.135135135,"the, ratg13, bat, identity, sars-cov-2"
12094,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.135135135,"the, and, sars-like, to, sars-cov"
12095,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.135135135,"the, of, sars-cov, and, mers-cov"
12096,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.135135135,"a, in, the, that, of"
12097,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.135135135,"the, sequence, that, is, to"
12098,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.135135135,"is, considered, to, the, in"
12099,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.135135135,"considered, a, similarity, the, in"
12100,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.135135135,"in, was, to, that, the"
12101,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.135135135,"sars-cov-2, to, spillover, of, the"
12102,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.135135135,"in, large, number, of, animal"
12103,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.135135135,"animal, in, market, to, and"
12104,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.135135135,"to, the, of, sars-cov-2, spillover"
12105,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.135135135,"a, to, the, of, sars-cov-2"
12106,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.135135135,"of, be, to, the, transmission"
12107,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.135135135,"a, the, to, and, sars-cov-2"
12108,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.135135135,"the, of, an, to, sars-cov-2"
12109,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.135135135,"and, a, of, the, is"
12110,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.135135135,"of, a, the, to, and"
12111,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.135135135,"the, of, may, be, and"
12112,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.135135135,"sars-cov, from, into, intermediate, as, and, to, for, the, that"
12113,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.135135135,"the, sequence, homology, with, sars-cov-2"
12114,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.135135135,"sars-cov-2, to, a, the, origin"
12115,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.135135135,"is, the, coronavirus, to, sequence"
12116,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.135135135,"coronaviruses, species, of, to, and"
12117,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.135135135,"the, to, which, humans,, and"
12118,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.135135135,"sars-cov, and, to, in, other"
12119,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.135135135,"the, in, from, animals, humans"
12120,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.135135135,"analysis, that, the, in, of"
12121,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.135135135,"bat, of, sars-cov-2, the, in"
12122,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.135135135,"that, the, of, genome, bat"
12123,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","civet cats and raccoon dogs  

are the intermediate hosts",0.135135135,"the, and, civet, raccoon, intermediate"
12124,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.135135135,"the, and, are, of, to"
12125,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.135135135,"the, to, of, and, transmitted"
12126,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.135135135,"animal, are, and, the, to"
12127,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.135135135,"to, the, of, and, be"
12128,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.135135135,"the, is, to, be, of"
12129,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.135135135,"this, bats, the, of, sars-cov-2"
12130,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.135135135,"a, that, originated, and, the"
12131,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.135135135,"not, been, that, the, a"
12132,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.135135135,"from, the, that, of, sars-cov-2"
12133,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.135135135,"a, of, natural, to, the"
12134,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.135135135,"that, the, of, from, bat"
12135,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.135135135,"the, was, that, people, of"
12136,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.135135135,"sars-cov-2, to, a, of, the"
12137,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.135135135,"to, the, a, from, sars-cov-2"
12138,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.135135135,"at, that, the, of, a"
12139,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.135135135,"that, the, of, to, lineage"
12140,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.135135135,"of, the, viruses, a, at"
12141,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.135135135,"this, a, that, the, of"
12142,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.135135135,"the, market, that, of, sars-cov-2"
12143,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.135135135,"of, sars-cov-2, to, the, animals"
12144,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.135135135,"a, of, the, with, and"
12145,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.135135135,"the, market, of, in, proximity"
12146,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.135135135,"in, this, the, and, of"
12147,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.135135135,"that, market, in, the, was"
12148,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.135135135,"sars-cov-2, and, was, in, animal"
12149,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.135135135,"that, the, likely, reservoir, sars-cov-2"
12150,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.135135135,"zoonotic, in, and, to, humans"
12151,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.135135135,"that, the, and, of, to"
12152,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.135135135,"the, in, humans, from, animals"
12153,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.135135135,",, it, that, the, from"
12154,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.135135135,"the, bat, and, 95%, with"
12155,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.135135135,"is, the, that, virus, and"
12156,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.135135135,"the, from, animals, is, also"
12157,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.135135135,"coronaviruses, species, to, of, and"
12158,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.135135135,"the, was, in, and, of"
12159,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.135135135,"host, and, was, in, the"
12160,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.135135135,"a, to, that, the, and"
12161,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.135135135,"a, the, genome, that, and"
12162,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.135135135,"studies, that, the, a, and"
12163,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.135135135,"the, to, as, of, intermediate"
12164,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.135135135,"has, that, the, of, from"
12165,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.135135135,"from, to, is, and, the"
12166,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.135135135,"the, and, a, that, originated"
12167,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.135135135,"the, that, from, be, as"
12168,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.135135135,"the, to, a, has, been"
12169,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.135135135,"has, been, with, sars-cov-2, a"
12170,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.135135135,"the, sars-cov-2, a, has, been"
12171,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.135135135,"he, from, the, of, spike"
12172,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.135135135,"the, bat, ratg13, identity, sars-cov-2"
12173,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.135135135,"bat, ratg13, the, with, sars-cov-2"
12174,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.135135135,"the, to, and, that, a"
12175,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.135135135,"that, the, recombination, and, of"
12176,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.135135135,"the, to, of, is, be"
12177,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.135135135,"the, to, bat, and, one"
12178,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.135135135,"the, to, bat, and, pangolin"
12179,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.135135135,"the, are, from, in, bats"
12180,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.135135135,"market, in, the, virus, was"
12181,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.135135135,"bats, are, in, to, virus"
12182,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.135135135,"bats, are, the, to, a"
12183,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.135135135,"a, at, that, the, of"
12184,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.135135135,"the, of, that, was, at"
12185,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.135135135,"is, that, a, of, the"
12186,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.135135135,"the, of, that, was, virus"
12187,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.135135135,"of, a, that, the, virus"
12188,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.135135135,"natural, origin, and, in, humans"
12189,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.135135135,"of, the, to, and, that"
12190,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.135135135,"and, that, is, bats, of"
12191,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.135135135,"of, be, to, the, that"
12192,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.135135135,"of, bats, to, and, the"
12193,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.135135135,"that, to, and, the, of"
12194,"civet cats and raccoon dogs  

are the intermediate hosts","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.135135135,"civet, and, raccoon, the, intermediate"
12195,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.135135135,"the, from, market, animals, in"
12196,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.135135135,"the, is, related, to, bats"
12197,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.135135135,"the, market, was, that, in"
12198,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.135135135,"the, virus, was, market, in"
12199,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.135135135,"virus, that, it, the, was"
12200,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.135135135,"the, to, of, sars-cov-2, bat"
12201,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.135135135,"bat, of, sars-cov-2, genome, the"
12202,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.135135135,"sars-cov-2, has, the, of, to"
12203,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.135135135,"the, of, sars-cov-2, to, evolutionary"
12204,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.135135135,"intermediate, and, humans, in, all"
12205,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.135135135,"that, from, the, bat, of"
12206,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.135135135,",, the, that, it, from"
12207,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.135135135,"the, has, that, of, from"
12208,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.135135135,"has, been, bat, that, human"
12209,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.135135135,"the, of, that, are, bat"
12210,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.135135135,"the, of, that, has, been"
12211,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.135135135,"the, viruses, are, of, spike"
12212,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.135135135,"is, that, and, bats, of"
12213,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.135135135,"most, of, have, that, by"
12214,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.135135135,"a, that, from, animal, human"
12215,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.135135135,"to, the, from, a, virus"
12216,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.135135135,"the, to, sars-cov-2, from, bats"
12217,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.135135135,"is, related, to, bats, the"
12218,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.135135135,"the, outbreak, from, in, to"
12219,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.135135135,"the, in, bats, to, of"
12220,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.135135135,"bats, in, closely, related, the"
12221,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.135135135,"to, and, animal, market, in"
12222,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.135135135,"to, have, the, market, in"
12223,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.135135135,"that, sars-cov-2, and, a, origin"
12224,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.135135135,"the, that, sars-cov-2, and, from"
12225,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.135135135,"that, the, from, humans, and"
12226,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.135135135,"that, the, sars-cov-2, and, from"
12227,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.135135135,"to, that, the, of, lineage"
12228,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.135135135,"of, to, the, that, had"
12229,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.135135135,"the, of, to, that, virus"
12230,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.135135135,"and, that, of, the, virus"
12231,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.135135135,"from, of, bats, to, the"
12232,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.135135135,"that, the, viruses, to, coronaviruses"
12233,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.135135135,"is, the, to, that, sequence"
12234,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.135135135,"the, genomic, to, that, of"
12235,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.135135135,"the, coronaviruses, to, that, sars-cov-2"
12236,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.135135135,"sequence, that, genomic, the, sars-cov-2"
12237,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.135135135,"the, of, to, is, that"
12238,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.135135135,"the, that, sars-cov-2, of, to"
12239,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.135135135,"the, of, to, that, sars-cov-2"
12240,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.135135135,"the, has, with, of, and"
12241,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.135135135,"virus, and, bat, has, of"
12242,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.135135135,"that, sars-cov-2, the, and, from"
12243,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.135135135,"analysis, the, that, sars-cov-2, a"
12244,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.135135135,"zoonotic, sars-cov-2, or, to, in"
12245,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.135135135,"sars-cov-2, to, in, host, or"
12246,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.135135135,"the, that, sars-, cov-2, at"
12247,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.135135135,"from, animals, in, the, market"
12248,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.135135135,"the, outbreak, in, to, from"
12249,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.135135135,"that, the, and, humans, from"
12250,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.135135135,"to, live, and, in, the"
12251,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.135135135,"of, the, genomic, that, to"
12252,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.135135135,"this, bat, is, sars-cov-2, that"
12253,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.135135135,"a, in, that, sars-cov-2, from"
12254,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.135135135,"sars-cov-2, with, and, a, that"
12255,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.135135135,"with, a, and, of, the"
12256,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.135135135,"the, genome, and, that, a"
12257,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.135135135,"the, that, presence, of, sars-cov-2"
12258,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.135135135,"the, of, sars-cov-2, humans, and"
12259,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.135135135,"the, of, and, transmitted, to"
12260,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.135135135,"a, the, has, been, to"
12261,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.135135135,"in, the, of, that, a"
12262,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.135135135,"that, the, sars-, cov-2, at"
12263,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.135135135,"that, the, of, similar, to"
12264,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.135135135,"a, that, with, the, in"
12265,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.135135135,"the, of, to, that, was"
12266,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.135135135,"related, pangolin, and, to, sars-cov-2."
12267,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.135135135,"to, be, of, the, transmission"
12268,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.135135135,"that, the, be, of, to"
12269,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.135135135,"the, analysis, that, sars-cov-2, a"
12270,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.135135135,"analysis, that, sars-cov-2, the, of"
12271,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.135135135,"is, the, to, in, considered"
12272,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.135135135,"the, have, in, market, to"
12273,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.135135135,"is, the, wuhan, to, covid-19"
12274,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.135135135,"to, and, was, the, sars-cov-2"
12275,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.135135135,"the, a, from, an, to"
12276,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.135135135,"sars-cov-2, closely, related, in, viruses"
12277,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.135135135,"rhinolophus, shameli, in, cambodia, sars-cov-2"
12278,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.135135135,"the, of, that, animal, origin"
12279,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.135135135,"has, been, the, in, of"
12280,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.135135135,"a, origin, of, sars-cov-2, the"
12281,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.135135135,"the, of, sars-cov-2, and, from"
12282,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.135135135,"the, of, from, a, recombinant"
12283,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.135135135,"the, sars-cov-2, was, found, to"
12284,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.135135135,"to, a, was, transmitted, the"
12285,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.135135135,"the, in, and, a, of"
12286,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.135135135,"a, bat, of, the, in"
12287,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.135135135,"the, of, and, has, been"
12288,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.135135135,"the, of, in, for, sars-cov-2"
12289,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.135135135,"the, sars-cov-2, a, cov, it"
12290,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.135135135,"a, the, in, similarity, considered"
12291,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.135135135,"a, with, the, sars-cov-2, in"
12292,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.135135135,"coronaviruses, viruses, to, the, that"
12293,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.135135135,"the, that, similar, to, of"
12294,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.135135135,"covid-19, is, to, the, wuhan"
12295,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.135135135,"sars-cov-2, was, and, to, the"
12296,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.135135135,"the, that, to, in, is"
12297,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.135135135,"the, sars-cov-2, to, in, is"
12298,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.135135135,"related, to, is, sars-cov-2, the"
12299,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.135135135,"sars-cov-2, in, rhinolophus, shameli, cambodia"
12300,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.135135135,"that, of, genome, a, bat"
12301,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.135135135,"a, of, bat, in, sars-cov-2"
12302,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.135135135,"that, the, sars-cov-2, to, is"
12303,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.135135135,"the, sars-cov-2, is, to, that"
12304,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.135135135,"the, that, sars-cov-2, to, similar"
12305,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.135135135,"the, human, to, with, market"
12306,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.135135135,"in, of, to, sars-cov-2, the"
12307,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.135135135,"the, in, of, to, sars-cov-2"
12308,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.135135135,"found, sars-cov-2, to, the, of"
12309,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.135135135,"ratg13, the, to, in, of"
12310,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.135135135,"the, of, sars-cov-2, and, an"
12311,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.135135135,"the, 95%, with, bat, and"
12312,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.135135135,"sars-cov-2, has, the, with, ratg13"
12313,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.135135135,"to, that, can, this, t"
12314,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.135135135,"sars-cov-2, to, a, and, the"
12315,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.135135135,"the, reported, in, that, was"
12316,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.135135135,"may, be, the, of, and"
12317,"This suggests that the BANAL series may be able to directly infect  

humans.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.135135135,"the, may, be, to, infect"
12318,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.135135135,"the, to, from, an, a"
12319,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.135135135,"the, market, to, with, human"
12320,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.135135135,"the, live, in, to, and"
12321,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.135135135,"the, species, to, sars-cov-2, and"
12322,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.135135135,"were, to, sars-cov-2, in, and"
12323,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.135135135,"sars-cov-2, the, at, and, to"
12324,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.135135135,"at, that, the, was, of"
12325,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.135135135,"this, that, the, outbreak, of"
12326,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.135135135,"similarity, to, bat, found, in"
12327,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.135135135,"the, that, sars-cov-2, of, from"
12328,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.135135135,"the, market, that, sars-cov-2, of"
12329,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.135135135,"proximity, of, the, market, in"
12330,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.135135135,"of, the, sars-cov-2, that, presence"
12331,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.135135135,"sars-cov-2, the, for, in, of"
12332,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.135135135,"the, site, sars-cov-2, and, to, a, of, in, coronaviruses, recombination"
12333,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.135135135,"the, has, been, a, of, that, from, to, rhinolophus, and"
12334,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.135135135,"bats, are, the, reservoir, for"
12335,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.135135135,"sars-cov-2, to, in, or, zoonotic"
12336,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.135135135,"in, a, the, of, pandemic"
12337,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.135135135,"is, or, of, the, natural"
12338,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.135135135,"the, is, sars-cov-2, a, or"
12339,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.135135135,"species, to, sars-cov-2, and, the"
12340,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.135135135,"the, that, sars-cov-2, to, coronaviruses"
12341,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.135135135,"bat, and, to, in, the"
12342,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.135135135,"the, bat, all, in, china"
12343,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.135135135,"and, in, the, to, sars"
12344,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.135135135,"the, to, bat, in, and"
12345,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.135135135,"the, of, to, and, in"
12346,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.135135135,"the, is, related, to, sars-cov-2"
12347,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.135135135,"viruses, closely, related, to, the"
12348,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.135135135,"of, the, spike, are, viruses"
12349,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.135135135,"the, of, closely, related, to"
12350,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.135135135,"the, that, to, sars-, and"
12351,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.135135135,"the, that, with, of, to"
12352,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.135135135,"the, rbd, of, to, that"
12353,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","This suggests that the BANAL series may be able to directly infect  

humans.",0.135135135,"the, to, may, be, infect"
12354,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","This suggests that the BANAL series may be able to directly infect  

humans.",0.135135135,"to, this, that, the, be"
12355,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.135135135,"he, from, the, spike, of"
12356,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.135135135,"a, viruses, at, the, of"
12357,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.135135135,"the, covid-19, virus, in, to"
12358,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.135135135,"of, covid-19, is, similar, the"
12359,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.135135135,"it, is, that, sars-cov-2, through"
12360,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.135135135,"the, of, china, a, animal, trading, in, wet, markets, and, animals, market, were, at, palm"
12361,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.135135135,"is, one, of, the, natural"
12362,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.135135135,"to, is, between, and, the"
12363,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.135135135,"suggesting, a, between, the, and"
12364,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.135135135,"the, animal, are, and, to"
12365,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.135135135,"the, sars, and, to, in"
12366,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.135135135,"are, zoonotic, in, and, to"
12367,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.135135135,"in, the, and, that, of, environmental, collected, huanan, all, market"
12368,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.135135135,"the, that, of, huanan, market, and, in, all, environmental, collected"
12369,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.135135135,"virus, is, to, sars-cov-2, its"
12370,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.135135135,"to, sars-cov-2, were, and, in"
12371,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.135135135,"the, and, to, in, of"
12372,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.135135135,"to, the, a, of, natural"
12373,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.135135135,"a, of, to, the, and"
12374,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.135135135,"of, to, which, the, in"
12375,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.135135135,"the, a, number, of, and"
12376,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.135135135,"sars-cov-2, animal, was, in, and"
12377,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.135135135,"natural, origin, in, and, humans"
12378,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.135135135,"the, genomic, sequence, that, sars-cov-2"
12379,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.135135135,"a, in, the, with, that"
12380,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.135135135,"a, sars-cov-2, with, the, in"
12381,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.135135135,"through, it, is, that, sars-cov-2"
12382,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.135135135,"sars-cov-2, is, a, that, through"
12383,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.135135135,"bats, of, to, the, reservoir"
12384,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.135135135,"of, the, that, is, to"
12385,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.135135135,"the, sars-, cov-2, is, bat"
12386,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.135135135,"of, the, that, which, by"
12387,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.135135135,"sars-cov-2, to, of, an, the"
12388,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.135135135,"that, the, virus, was, of"
12389,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.135135135,"that, the, virus, of, to"
12390,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.135135135,"t, can, that, to, this"
12391,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.135135135,"we, that, sars-cov-2, probably, the"
12392,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.135135135,"sars-cov-2, from, nearly, identical, and"
12393,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.135135135,"the, to, one, bat, and"
12394,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.135135135,"the, genome, of, that, bat"
12395,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.135135135,"that, a, bat, genome, of"
12396,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.135135135,"that, the, most, a, bat"
12397,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.135135135,"the, of, showed, identity, sars-cov"
12398,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.135135135,"the, humans,, which, to, and"
12399,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.135135135,"the, and, to, that, sars-"
12400,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.135135135,"the, analysis, that, in, of"
12401,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.135135135,"the, virus, to, in, covid-19"
12402,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.135135135,"analysis, of, the, that, virus"
12403,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.135135135,"and, that, in, the, of"
12404,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.135135135,"zoonotic, humans, in, and, to"
12405,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.135135135,"are, zoonotic, and, in, to"
12406,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.135135135,"have, that, most, by, of"
12407,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.135135135,"reported, that, the, was, in"
12408,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.135135135,"the, of, which, that, by"
12409,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.135135135,"the, in, of, that, was"
12410,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.135135135,"that, the, virus, it, was"
12411,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.135135135,"of, the, covid-19, is, similar"
12412,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.135135135,"that, was, the, of, people"
12413,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.135135135,"the, is, of, natural, or"
12414,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.135135135,"the, is, one, of, natural"
12415,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.135135135,"that, natural, the, of, is"
12416,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.135135135,"the, natural, reservoir, is, of"
12417,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.135135135,"the, all, bat, in, china"
12418,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.135135135,"the, sars-, cov-2, bat, is"
12419,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.135135135,"the, is, to, and, from"
12420,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.135135135,"the, between, and, is, to"
12421,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.135135135,"the, is, and, would, to"
12422,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.135135135,"in, the, was, host, and"
12423,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.135135135,"all, in, humans, and, intermediate"
12424,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.135135135,"the, in, closely, related, bats"
12425,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.135135135,"are, virus, bats, to, in"
12426,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.135135135,"palm, were, in, the, china, wet, market, a, at, animals, and, of, animal, trading, markets"
12427,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.135135135,"a, that, the, of, this"
12428,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.135135135,"of, the, covid-19, and, that"
12429,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.135135135,"the, of, that, this, outbreak"
12430,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.135135135,"and, the, of, that, a"
12431,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.135135135,"of, a, that, the, and"
12432,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.135135135,"of, the, and, that, a"
12433,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.135135135,"that, and, a, the, of"
12434,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.135135135,"from, the, animals, also, is"
12435,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.135135135,"to, from, a, of, rhinolophus, the, and, has, been, that"
12436,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.135135135,"a, has, been, with, sars-cov-2"
12437,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.135135135,"has, been, that, human, bat"
12438,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.135135135,"that, sars-cov-2, has, and, with"
12439,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.135135135,"analysis, that, the, virus, of"
12440,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.135135135,"the, virus, and, to, of"
12441,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.135135135,"to, the, of, zoonotic, virus"
12442,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.135135135,"a, natural, origin, of, likely"
12443,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.135135135,"that, a, of, sars-cov-2, been"
12444,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.135135135,"not, a, that, the, been"
12445,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.135135135,"from, as, intermediate, that, to, for, sars-cov, and, the, into"
12446,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.135135135,"such, have, been, by, and, in, to, the, of, sars-cov-2"
12447,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.135135135,"found, the, sars-cov-2, was, to"
12448,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.135135135,"that, the, virus, of, and"
12449,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.135135135,"a, origin, prior, the, and"
12450,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.135135135,"such, and, to, by, the, of, sars-cov-2, have, been, in"
12451,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.135135135,"from, nearly, identical, and, sars-cov-2"
12452,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.135135135,"similarity, sars-cov-2, bat, ratg13, than"
12453,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.135135135,"be, that, from, the, as"
12454,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.135135135,"that, the, most, evidence, be"
12455,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.135135135,"other, sars-cov-2, to, the, of"
12456,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.135135135,"the, to, be, its, of"
12457,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.135135135,"sars-cov, and, sars-cov-2, bat, of"
12458,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.135135135,"sars-cov-2, and, bat, ratg13, of"
12459,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.135135135,"the, animals, to, sars-cov-2, of"
12460,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.135135135,"of, in, to, which, the"
12461,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.135135135,"the, most, evidence, that, be"
12462,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.135135135,"the, pangolin, to, bat, and"
12463,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.135135135,"bats, that, are, hosts, for"
12464,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.135135135,"the, sars-cov-2, reservoir, likely, that"
12465,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.135135135,"are, the, bats, to, a"
12466,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.135135135,"the, sars-cov-2, in, of, bat"
12467,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.135135135,"the, genome, of, sars-cov-2, bat"
12468,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.135135135,"the, origin, of, sars-cov-2, a"
12469,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.135135135,"the, of, a, in, bat"
12470,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.135135135,"bat, similarity, to, found, in"
12471,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.135135135,"pangolin, and, related, to, sars-cov-2."
12472,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.135135135,"sars-cov-2, that, is, this, bat"
12473,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.135135135,"this, the, probable, bat, cov"
12474,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.135135135,"that, sars-cov-2, is, to, originated"
12475,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same",0.135135135,"the, and, bat, cov, same"
12476,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.135135135,"the, sars-cov-2, is, same, with"
12477,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.135135135,"this, bat, cov, the, probable"
12478,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.135135135,"bat, similarity, sars-cov-2, than, ratg13"
12479,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.135135135,"the, that, sars-cov-2, we, probably"
12480,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.135135135,"that, sars-cov-2, cov, the, origin"
12481,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.135135135,"the, sars-cov-2, bats, of, this"
12482,"�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.135135135,"cov, bat, and, the, same"
12483,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.135135135,"in, that, sars-cov-2, originated, or"
12484,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.135135135,"to, the, a, sars-cov-2, origin"
12485,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.135135135,"that, sars-cov-2, a, origin, and"
12486,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.135135135,"the, of, sars-cov-2, other, to"
12487,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.135135135,"that, sars-cov-2, the, origin, cov"
12488,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.135135135,"that, the, of, are, bat"
12489,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.135135135,"has, with, that, and, sars-cov-2"
12490,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.135135135,"the, to, of, sars-cov-2, and"
12491,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.135135135,"to, the, of, bat-sl-cov-2,, with"
12492,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.135135135,"of, the, and, with, identity"
12493,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.135135135,"sars-cov-2, is, the, same, with"
12494,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.135135135,"the, is, and, with, of"
12495,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.135135135,"analysis, of, the, that, sars-cov-2"
12496,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.135135135,"that, the, in, and, of"
12497,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.135135135,"that, the, of, sars-cov-2, and"
12498,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.135135135,"the, sars-cov, and, mers-cov, of"
12499,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.135135135,"the, that, are, and, of"
12500,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.135135135,"studies, the, and, that, a"
12501,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.135135135,"hosts, and, are, the, of"
12502,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.135135135,"a, number, of, and, the"
12503,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.135135135,"virus, and, evolutionary, has, of"
12504,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.135135135,"of, the, has, and, with"
12505,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.135135135,"the, that, be, and, of"
12506,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.135135135,"of, that, the, recombination, and"
12507,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.135135135,"sars-cov-2, from, to, bats, the"
12508,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.135135135,"the, that, was, to, of"
12509,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.135135135,"that, the, rbd, of, to"
12510,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.135135135,"the, of, a, recombinant, from"
12511,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.135135135,"to, the, zoonotic, of, virus"
12512,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.135135135,"the, of, with, bat-sl-cov-2,, to"
12513,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.135135135,"the, that, in, animal, for"
12514,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.135135135,"is, sars-cov-2, to, that, originated"
12515,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.135135135,"the, sars-cov-2, of, is, that"
12516,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.135135135,"an, of, sars-cov-2, and, the"
12517,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.135135135,"the, between, and, suggesting, a"
12518,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.135135135,"the, in, that, animal, for"
12519,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.135135135,"that, from, animal, a, human"
12520,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.135135135,"sars-cov-2, from, a, that, in"
12521,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.135135135,"that, sars-cov-2, originated, in, or"
12522,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.135135135,"the, natural, reservoir, of, and"
12523,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.135135135,"is, of, the, natural, reservoir"
12524,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.135135135,"to, is, and, would, the"
12525,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.135135135,"a, bat, in, of, sars-cov-2"
12526,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.135135135,"the, origin, a, prior, and"
12527,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.135135135,"the, to, that, in, was"
12528,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.135135135,"the, to, that, sars-cov-2, in"
12529,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.135135135,"to, the, sequence, coronavirus, is"
12530,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.135135135,"the, of, ratg13, to, in"
12531,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.135135135,"the, of, to, be, its"
12532,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.135135135,"the, closely, related, to, of"
12533,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.135135135,"of, sars-cov-2, and, bat, ratg13"
12534,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.135135135,"sars-cov-2, is, a, that, the"
12535,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.135135135,"the, is, sars-cov-2, or, a"
12536,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.134831461,"from, into, and, before, this, by, the, of, that, sars-cov-2, in, a"
12537,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.134831461,"a, of, the, from, this, by, that, sars-cov-2, and, in, before, into"
12538,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.134751773,"early, cases, with, the, of, all, suggesting, a, or, to, that, infections, in, this, sars, live, animal, than, at"
12539,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.134751773,"this, that, sars, a, the, animal, than, or, with, early, cases, of, in, at, suggesting, infections, all, to, live"
12540,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.134615385,"of, the, in, and, that, a, group"
12541,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.134615385,"to, the, of, from, occurred, virus, with"
12542,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.134615385,"it, is, a, of, sars-cov-2, the, described"
12543,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.134615385,"a, that, the, was, laboratory, in, sars-cov-2"
12544,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.134615385,"the, genetic, in, from, 2020, that, was"
12545,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.134615385,"these, are, viruses, to, the, and, that"
12546,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.134615385,"to, that, belongs, the, have, as, sars-cov-2"
12547,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.134615385,"was, that, the, sars-cov-2, same, and, to"
12548,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.134615385,"to, that, sars-cov-2, the, be, origin, of"
12549,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.134615385,"sars-cov-2, is, a, and, be, to, coronavirus"
12550,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.134615385,"and, the, of, to, be, sars-cov-2, is"
12551,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.134615385,"that, of, is, in, sars-cov-2, analysis, the"
12552,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.134615385,"the, to, that, in, animals, and, humans"
12553,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.134615385,"the, from, that, to, humans,, and, animals"
12554,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.134615385,"and, a, which, zoonotic, that, disease, in"
12555,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.134615385,"a, the, been, by, that, other, virus"
12556,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.134615385,"that, a, the, of, sars-cov-2, evidence, to"
12557,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.134615385,"the, of, to, that, sars-cov-2, this, a"
12558,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.134615385,"that, sars-cov-2, a, the, of, at, from"
12559,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.134615385,"are, a, to, coronaviruses,, sars-cov-2, the, bat"
12560,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.134615385,"that, and, be, sars-cov-2, transmission, to, the"
12561,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.134615385,"that, sars-cov-2, the, with, at, of, and"
12562,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.134615385,"the, of, more, than, to, that, and"
12563,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.134615385,"evidence, to, the, that, sars-cov-2, a, of"
12564,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.134615385,"that, the, virus, in, to, who, market"
12565,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.134615385,"according, to, the, and, is, be, intermediate"
12566,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.134615385,"the, pangolin, and, that, for, a, of"
12567,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.134615385,"the, horseshoe, to, of, bat, (rhinolophus, and"
12568,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.134615385,"to, the, of, from, a, virus, with"
12569,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.134615385,"to, humans, can, with, of, and, their"
12570,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.134615385,"that, a, the, of, sars-cov-2, and, to"
12571,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.134615385,"sars-cov-2, is, that, humans, on, to, the"
12572,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.134615385,"studies, on, sequences, the, of, based, and"
12573,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.134615385,"the, of, is, to, sars-cov-2, that, which"
12574,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.134615385,"to, the, market, who, in, that, virus"
12575,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.134615385,"in, humans, through, that, the, and, infected"
12576,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.134615385,"in, the, that, animals, to, humans, and"
12577,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.134615385,"and, the, of, to, be, that, is"
12578,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.134615385,"according, to, is, be, and, the, intermediate"
12579,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.134615385,"to, natural, the, sars-, and, is, be"
12580,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.134615385,"of, it, is, the, bat, and, for"
12581,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.134615385,"the, of, natural, a, human, as, and"
12582,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.134615385,"have, a, of, in, the, as, china"
12583,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.134615385,"the, was, to, and, that, sars-cov-2, same"
12584,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.134615385,"analysis, of, the, sequence, that, and, sars-cov-2"
12585,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.134615385,"the, of, sars-cov-2, to, is, and, between"
12586,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.134615385,"to, that, sars-cov-2, similarity, the, virus, of"
12587,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.134615385,"of, from, bats, to, is, in, the"
12588,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.134615385,"that, from, humans, is, sars-cov-2, species, the"
12589,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.134615385,"sars-cov-2, is, that, humans, through, contact, to"
12590,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.134615385,"of, the, covid-19, symptom, onset, in, with"
12591,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.134615385,"a, coronavirus, the, with, to, of, sars-"
12592,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.134615385,"et, that, by, a, and, the, sars-cov-2"
12593,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.134615385,"the, that, of, are, genomic, sequences, within"
12594,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.134615385,"analysis, that, the, of, most, a, coronavirus"
12595,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.134615385,"that, the, hosts, for, based, on, comparative"
12596,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.134615385,"sars-cov-2, a, of, and, that, the, with"
12597,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.134615385,"sars-cov-2, is, to, be, a, coronavirus, and"
12598,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.134615385,"a, sars-, to, the, coronavirus, of, with"
12599,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.134615385,"that, of, is, a, sars-cov-2, analysis, the"
12600,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.134615385,"the, for, a, of, that, pangolin, and"
12601,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.134615385,"that, a, of, pangolin, and, the, for"
12602,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.134615385,"the, and, has, a, in, bat, of"
12603,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.134615385,"for, were, found, to, novel, suggesting, that"
12604,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.134615385,"more, than, of, the, to, and, that"
12605,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.134615385,"with, the, and, for, of, a, to, that, in, this, is, sars-cov-2, more, than"
12606,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.134615385,"the, analysis, that, sars-cov-2, is, in, of"
12607,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.134615385,"is, that, sars-cov-2, the, species, humans, from"
12608,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.134615385,"analysis, of, the, that, sars-cov-2, is, a"
12609,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.134615385,"collected, and, were, of, which, in, the"
12610,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.134615385,"sequence, that, the, of, sars-cov-2, and, analysis"
12611,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.134615385,"and, of, sars-cov-2, in, an, the, to"
12612,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.134615385,"sars-cov-2, is, to, be, of, and, the"
12613,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.134615385,"that, the, hosts, for, a, of, and"
12614,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.134615385,"the, that, to, be, sars-cov-2, and, transmission"
12615,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.134615385,"that, sars-cov-2, was, a, laboratory, the, in"
12616,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.134615385,"was, in, a, and, to, sars-cov-2, the"
12617,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.134615385,"a, to, common, in, sars-cov-2, the, and"
12618,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.134615385,"the, between, sars-cov-2, and, of, is, to"
12619,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.134615385,"of, the, covid-19, in, with, symptom, onset"
12620,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.134615385,"that, was, from, the, genetic, in, 2020"
12621,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.134615385,"a, at, that, the, of, sars-cov-2, from"
12622,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.134615385,"the, of, to, and, horseshoe, bat, (rhinolophus"
12623,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.134615385,"this, and, bat, the, between, viruses, in"
12624,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.134615385,"a, the, was, to, and, in, sars-cov-2"
12625,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.134615385,"the, two, in, and, sars-cov-2, a, with"
12626,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.134615385,"in, the, virus, is, closely, related, to"
12627,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.134615385,"a, are, to, bat, coronaviruses,, the, sars-cov-2"
12628,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.134615385,"a, the, to, common, and, in, sars-cov-2"
12629,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.134615385,"other, sars-cov-2, are, to, and, a, the"
12630,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.134615385,"through, that, the, in, and, humans, infected"
12631,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.134615385,"in, the, of, for, more, than, is, to, that, sars-cov-2, with, and, this, a"
12632,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.134615385,"the, of, and, which, were, collected, in"
12633,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.134615385,"the, and, huanan, of, a, to, 19"
12634,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.134615385,"a, and, to, 19, of, the, huanan"
12635,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.134615385,"the, sequences, within, genomic, are, that, of"
12636,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.134615385,"on, the, that, sars-cov-2, is, to, humans"
12637,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.134615385,"is, contact, humans, that, sars-cov-2, to, through"
12638,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.134615385,"a, of, the, described, it, is, sars-cov-2"
12639,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.134615385,"the, of, it, is, that, sars-cov-2, a"
12640,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.134615385,"it, is, that, sars-cov-2, a, the, of"
12641,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.134615385,"also, of, sars-cov-2, in, an, the, to"
12642,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.134615385,"analysis, the, of, a, coronavirus, that, most"
12643,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.134615385,"covid-19, a, in, the, that, originated, animal"
12644,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.134615385,"the, humans,, that, from, animals, to, and"
12645,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.134615385,"evidence, to, that, sars-, belongs, the, and"
12646,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.134615385,"the, virus, covid-19, of, to, that, and"
12647,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.134615385,"to, humans, through, of, and, in, bats"
12648,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.134615385,"are, pathogens, and, to, zoonotic, in, covs"
12649,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.134615385,"for, the, of, bat, is, and, it"
12650,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.134615385,"this, in, the, of, that, was, to"
12651,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.134615385,"the, in, china, have, as, a, of"
12652,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.134615385,"to, humans, and, their, can, with, of"
12653,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.134615385,"in, bats, and, to, humans, through, of"
12654,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.134615385,"in, two, of, guangxi, and, provinces, have"
12655,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.134615385,"in, the, of, is, sars-cov-2, at, virus"
12656,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.134615385,"a, that, the, virus, been, by, other"
12657,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.134615385,"and, a, of, is, the, viral, human"
12658,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.134615385,"a, the, as, natural, of, and, human"
12659,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.134615385,"to, the, sars-, and, natural, is, be"
12660,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.134615385,"comparative, based, on, the, that, hosts, for"
12661,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.134615385,"is, the, closely, related, virus, to, in"
12662,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.134615385,"the, of, virus, to, that, and, a"
12663,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.134615385,"in, an, of, to, sars-cov-2, and, the"
12664,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.134615385,"the, in, of, an, to, sars-cov-2, also"
12665,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.134615385,"viral, and, human, a, of, the, is"
12666,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.134615385,"of, the, in, and, sars-cov-2, a, viruses"
12667,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.134615385,"sars-cov-2, also, to, and, a, the, of"
12668,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.134615385,"two, of, have, in, and, guangxi, provinces"
12669,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.134615385,"the, by, et, that, sars-cov-2, and, a"
12670,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.134615385,"(2020), that, the, of, sars-cov-2, and, been"
12671,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.134615385,"a, of, and, that, the, in, group"
12672,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.134615385,"in, a, with, two, and, sars-cov-2, the"
12673,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.134615385,"and, a, of, sars-cov-2, in, the, viruses"
12674,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.134615385,"the, viruses, and, are, that, these, to"
12675,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.134615385,"the, has, of, that, coronavirus, from, and"
12676,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.134615385,"(2020), that, been, of, and, the, sars-cov-2"
12677,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.134615385,"this, and, viruses, bat, between, in, the"
12678,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.134615385,"have, that, sars-cov-2, belongs, to, as, the"
12679,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.134615385,"the, evidence, that, belongs, to, sars-, and"
12680,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.134615385,"the, of, more, to, sars-, cov-2, than"
12681,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.134615385,"studies, based, on, the, of, and, sequences"
12682,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.134615385,"the, of, to, that, sars-cov-2, and, a"
12683,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.134615385,"are, a, other, to, sars-cov-2, the, and"
12684,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.134615385,"and, also, a, of, sars-cov-2, the, to"
12685,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.134615385,"a, of, and, that, the, hosts, for"
12686,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.134615385,"the, of, that, sars-cov-2, is, which, to"
12687,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.134615385,"the, origin, of, be, to, that, sars-cov-2"
12688,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.134615385,"the, similarity, sars-cov-2, of, virus, to, that"
12689,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.134615385,"to, occurred, with, the, of, from, virus"
12690,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.134615385,"the, virus, a, of, to, with, from"
12691,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.134615385,"the, that, a, in, animal, covid-19, originated"
12692,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.134615385,"were, found, to, suggesting, that, for, novel"
12693,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.134615385,"and, which, a, zoonotic, disease, that, in"
12694,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.134615385,"covs, are, zoonotic, pathogens, in, and, to"
12695,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.134615385,"to, sars-, cov-2, the, of, more, than"
12696,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.134453782,"the, for, of, a, to, team, that, were, covid-19, in, this, is, live, likely, market, meat,"
12697,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.134453782,"the, huanan, market, of, 41, cases, january, were, to, by, and, health, with, a, had, an"
12698,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.134453782,"to, the, sars, were, as, and, a, in, of, from, sequence, that, an, identical, humans, found"
12699,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.134453782,"in, the, of, as, an, sars, a, found, that, from, humans, were, identical, to, and, sequence"
12700,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.134453782,"an, a, the, huanan, with, 41, health, and, market, january, of, cases, were, to, by, had"
12701,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.134453782,"in, a, team, of, to, the, likely, that, covid-19, this, is, were, live, market, for, meat,"
12702,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.134328358,"for, the, of, intermediate, humans,, from, humans, as, to"
12703,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.134328358,"from, intermediate, as, to, possibility, for, the, of, sars-cov-2"
12704,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.134328358,"lineage, at, the, that, of, sars-cov-2, this, from, a"
12705,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.134328358,"collected, by, the, that, cases, were, with, market,, earliest"
12706,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.134328358,"the, of, raccoon, in, from, market, that, this, was"
12707,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.134328358,"the, in, of, to, that, we, this, was, virus"
12708,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.134328358,"in, the, and, that, of, were, to, huanan, market"
12709,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.134328358,"the, of, an, that, virus, from, identical, to, and"
12710,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.134328358,"that, of, from, to, a, coronavirus, pangolin, with, the"
12711,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.134328358,"the, china, a, to, in, and, market, virus, was"
12712,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.134328358,"the, as, of, that, from, to, bat, such, and"
12713,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.134328358,"sars-cov-2, from, a, of, in, the, and, has, with"
12714,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.134328358,"to, the, 2, been, in, of, and, that, a"
12715,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.134328358,"the, a, of, to, with, that, coronavirus, from, pangolin"
12716,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.134328358,"of, that, the, is, a, homology, from, species, intermediate"
12717,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.134328358,"the, of, and, were, species, from, in, humans, to"
12718,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.134328358,"in, of, the, that, was, this, from, raccoon, market"
12719,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.134328358,"samples, at, the, that, was, of, in, this, from"
12720,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.134328358,"from, intermediate, raccoon, this, was, the, of, that, in"
12721,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.134328358,"has, a, sars-cov-2, and, with, the, of, from, in"
12722,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.134328358,"been, and, in, to, the, evidence, of, sars-cov-2, has"
12723,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.134328358,"in, less, the, of, that, for, as, also, virus, similar, to, different, infected, a, is, closely, related, and"
12724,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.134328358,"genetic, that, a, natural, of, the, virus, is, likely"
12725,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.134328358,"the, earliest, cases, that, with, were, market,, by, collected"
12726,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.134328358,"and, the, of, infected, also, to, similar, as, a, closely, related, different, that, in, for, virus, is, less"
12727,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.134328358,"to, humans,, the, of, from, as, intermediate, for, humans"
12728,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.134328358,"in, from, species, of, were, to, and, the, humans"
12729,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.134328358,"the, virus, an, to, identical, that, of, and, from"
12730,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.134328358,"a, at, that, the, of, sars-cov-2, from, this, lineage"
12731,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.134328358,"the, of, in, samples, from, that, this, was, at"
12732,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.134328358,"that, the, of, were, in, to, and, huanan, market"
12733,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.134328358,"in, of, to, the, we, virus, that, was, this"
12734,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.134328358,"to, humans., this, was, the, of, that, sars-cov-2, in"
12735,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.134328358,"that, of, from, intermediate, is, a, homology, species, the"
12736,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.134328358,"possible, a, from, bat, another, diversity, of, species,, as"
12737,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.134328358,"in, the, of, 2, to, that, been, and, a"
12738,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.134328358,"another, of, bat, a, from, diversity, species,, as, possible"
12739,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.134328358,"and, the, virus, was, to, a, market, in, china"
12740,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.134328358,"the, of, that, from, to, bat, such, as, and"
12741,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.134328358,"to, the, possibility, of, sars-cov-2, from, as, intermediate, for"
12742,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.134328358,"the, of, raccoon, in, from, that, this, intermediate, was"
12743,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.134328358,"the, in, of, to, that, sars-cov-2, this, was, humans."
12744,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.134328358,"the, of, is, likely, natural, a, virus, that, genetic"
12745,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.134328358,"evidence, to, sars-cov-2, of, in, the, and, has, been"
12746,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.134146341,"in, the, and, of, were, to, huanan, market., total,, 8, market"
12747,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.134146341,"of, to, and, 8, the, huanan, market, were, market., in, total,"
12748,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.134020619,"the, of, to, that, were, covid-19, in, this, is, animal, likely, infected, market"
12749,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.134020619,"the, live, animals, in, a, of, as, with, was, that, infected, were, market"
12750,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.134020619,"was, that, the, infected, with, in, market, live, animals, were, as, a, of"
12751,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.134020619,"the, of, infected, that, were, to, animal, market, in, is, this, likely, covid-19"
12752,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.133928571,"the, to, in, a, for, of, as, with, likely, sars, that, virus, were, and, palm"
12753,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.133928571,"for, the, of, and, were, that, virus, palm, a, in, sars, likely, with, as, to"
12754,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.133928571,"spread, reservoir, as, civets,, and, multiple, to, was, for, by, the, of, that, in, a"
12755,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.133928571,"the, to, in, a, for, spread, of, as, reservoir, was, that, multiple, by, and, civets,"
12756,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.133333333,"of, in, coronaviruses, bats"
12757,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.133333333,"presence, of, a, in"
12758,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.133333333,"coronaviruses, related, to, sars-cov-2, in, and"
12759,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.133333333,"animal, a, are, coronaviruses, in, species"
12760,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.133333333,"of, species, in, but, viruses, a"
12761,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.133333333,"many, such, in, and"
12762,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.133333333,"bat, and, to, in"
12763,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.133333333,"virus, in, genome, sars-cov-2"
12764,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.133333333,"the, also, bats, are"
12765,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.133333333,"may, have, of, virus, with, to, and, the"
12766,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.133333333,"the, of, with, and, to, sars-cov"
12767,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.133333333,"from, genetically, it, to, the, of, that, sars-cov-2, have, been"
12768,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.133333333,"the, genetic, of, sars-cov-2, coronaviruses, to"
12769,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.133333333,"it, engineered, from, is, unlike, any"
12770,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.133333333,"to, and, have, a, site, the, which, is"
12771,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.133333333,"is, sars-cov-2, and, bat, to, the, between, in"
12772,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.133333333,"that, the, is, sars-cov-2, a, laboratory"
12773,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.133333333,"genetic, sars-cov-2, and, virus, is, that"
12774,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.133333333,"genome, the, to, bat, that, sars-cov-2"
12775,"expended to make the simple point 

that COVID-19 had a natural origin.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.133333333,"to, the, that, natural"
12776,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.133333333,"been, and, of, natural, origin, has"
12777,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.133333333,"a, of, and, the"
12778,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.133333333,"of, the, viruses, a"
12779,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.133333333,"a, the, of, and"
12780,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.133333333,"that, sars-cov-2, to, genome, bat, the"
12781,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.133333333,"showed, that, the, genome, bat, covid-19"
12782,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.133333333,"analysis, in, protein, of, pangolin, that, were, intermediate"
12783,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.133333333,"the, of, and, mers-cov"
12784,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.133333333,"the, bat, with, sars-cov-2"
12785,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.133333333,"sars-cov-2, is, in, bat"
12786,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.133333333,"in, the, of, sequence, sars-cov-2, to"
12787,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.133333333,"in, of, covs, genome, and, to"
12788,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.133333333,"sars-cov, and, sars-like, sars-cov-2, covs, with"
12789,Bats are likely reservoir hosts for SARS-CoV-2,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.133333333,"are, sars-cov-2"
12790,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.133333333,"are, to, of, sars-cov-2"
12791,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.133333333,"sars-cov-2, to, the, reservoirs, and, of"
12792,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.133333333,"that, and, be, sars-cov-2, to, humans, the, between"
12793,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.133333333,"have, that, the, of, including, and"
12794,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.133333333,"has, its, in, bats"
12795,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.133333333,"the, of, more, than, and, bats"
12796,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.133333333,"are, and, the, virus, bats, to, a, in"
12797,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.133333333,"of, virus, that, is, to, the, and, for"
12798,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.133333333,"that, the, in, to, a, and"
12799,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.133333333,"is, a, virus, that, to, the"
12800,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.133333333,"of, the, covid-19, were, to, that"
12801,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.133333333,"of, covid-19, in, the, market, wuhan"
12802,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.133333333,"the, of, in, market, that, this"
12803,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.133333333,"the, in, of, to, that, this"
12804,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.133333333,"that, origin, of, the, is, likely"
12805,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.133333333,"that, to, on, the, origin, of"
12806,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.133333333,"to, and, in, animal"
12807,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.133333333,"the, of, an, a, to, and, later, adapted"
12808,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.133333333,"the, is, sars-cov-2, a"
12809,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.133333333,"the, bats, species, most, of, and"
12810,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.133333333,"that, has, the, evolutionary, of, and"
12811,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.133333333,"the, and, mers-cov, of"
12812,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.133333333,"the, be, and, of"
12813,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.133333333,"hosts, and, the, of"
12814,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.133333333,"of, natural, and, the"
12815,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.133333333,"be, the, and, of"
12816,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.133333333,"are, and, the, bats"
12817,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.133333333,"at, with, sars-cov-2, the, sequence, of"
12818,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",Bats are likely reservoir hosts for SARS-CoV-2,0.133333333,"sars-cov-2, are"
12819,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",Bats are likely reservoir hosts for SARS-CoV-2,0.133333333,"bats, are, hosts, for"
12820,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",Bats are likely reservoir hosts for SARS-CoV-2,0.133333333,"for, sars-cov-2"
12821,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.133333333,"the, origin, a, zoonotic"
12822,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.133333333,"from, to, is, the"
12823,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.133333333,"coronavirus, the, with, bats,"
12824,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.133333333,"the, sars-cov-2, is, with"
12825,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.133333333,"was, in, other, and, to, the"
12826,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.133333333,"the, of, lineage, that, sars-cov-2, in"
12827,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.133333333,"the, of, sars-cov-2, bat"
12828,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.133333333,"the, of, in, is"
12829,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.133333333,"the, of, in, bat"
12830,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.133333333,"is, in, the, of"
12831,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.133333333,"is, the, sars-cov-2, in"
12832,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.133333333,"the, of, sars-cov-2, protein, is, that"
12833,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.133333333,"is, and, that, of, sars-cov-2, to"
12834,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.133333333,"to, and, of, is, that, bat"
12835,"the close relation  

between SARS coronavirus and 2019-nCoV","civet cats and raccoon dogs  

are the intermediate hosts",0.133333333,"the, and"
12836,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","civet cats and raccoon dogs  

are the intermediate hosts",0.133333333,"the, and, intermediate, hosts"
12837,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","civet cats and raccoon dogs  

are the intermediate hosts",0.133333333,"intermediate, and, the, civet"
12838,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.133333333,"the, was, from, a, at, and, to, with"
12839,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","with the first case being linked to  

a seafood market",0.133333333,"first, a, seafood, market"
12840,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","with the first case being linked to  

a seafood market",0.133333333,"linked, to, the, seafood"
12841,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.133333333,"to, the, of, sars-cov-2, from, this"
12842,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.133333333,"is, the, to, be, in, of"
12843,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.133333333,"the, a, zoonotic, origin"
12844,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.133333333,"that, the, zoonotic, and"
12845,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.133333333,"that, a, origin, and"
12846,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.133333333,"in, by, a, and, which, the"
12847,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.133333333,"a, that, the, and"
12848,"expended to make the simple point 

that COVID-19 had a natural origin.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.133333333,"the, that, had, a"
12849,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.133333333,"the, was, not, it, that, been"
12850,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.133333333,"coronaviruses, are, in, a, animal, species"
12851,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.133333333,"a, between, sars-cov-2, and, from, bat, in, china"
12852,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.133333333,"studies, have, to, a, high, and, species, as"
12853,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.133333333,"a, from, an, host, as, to"
12854,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.133333333,"bat, similarity, to, sars-cov-2, found, in"
12855,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.133333333,"that, from, to, a"
12856,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.133333333,"sars-cov-2, from, a, that"
12857,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.133333333,"the, of, sars-cov-2, humans"
12858,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.133333333,"hypothesis, the, of, that, sars-cov-2, to"
12859,The FCS of SARS-CoV-2 was not bioengineered—full stop.,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.133333333,"the, of, was, not"
12860,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.133333333,"that, the, of, and, coronavirus, from"
12861,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.133333333,"phylogenetic, that, the, at, of, and"
12862,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.133333333,"the, sars-cov-2, to, from, of, this"
12863,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.133333333,"the, sars-cov-2, and, of, to, that"
12864,"This suggests that the BANAL series may be able to directly infect  

humans.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.133333333,"that, the, be, to"
12865,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.133333333,"the, that, sars-cov-2, in, lineage, of"
12866,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.133333333,"in, the, that, closely, related, to"
12867,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.133333333,"the, to, are, in"
12868,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.133333333,"a, is, in, this"
12869,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.133333333,"this, the, origin, of"
12870,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.133333333,"the, been, from, animal, in, and"
12871,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.133333333,"at, within, the, sars-cov-2, that, than"
12872,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.133333333,"to, humans, from, and, of, sars-cov-2"
12873,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.133333333,"were, to, sars-cov-2, in, and, from"
12874,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.133333333,"that, from, a, zoonotic"
12875,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.133333333,"of, scientific, supports, the"
12876,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.133333333,"the, of, most, natural, or, evidence"
12877,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.133333333,"the, of, that, were, to, covid-19"
12878,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.133333333,"is, unlike, any, from, it, engineered"
12879,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.133333333,"there, is, and, it, that, sars-cov-2, to, an"
12880,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.133333333,"that, a, in, sars-cov-2"
12881,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.133333333,"sars-cov-2, a, in, or"
12882,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.133333333,"a, genome, from, market, in, that, the, to"
12883,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.133333333,"in, the, of, as, was, a, found, that, virus, from, were, to"
12884,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.133333333,"the, first, was, in, that, as, for, sars-cov-2."
12885,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.133333333,"from, a, is, to, in, that"
12886,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.133333333,"that, the, to, with, a, and"
12887,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.133333333,"similarity, and, bat, to, the, that"
12888,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.133333333,"animals, from, that, virus, and, the"
12889,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.133333333,"is, the, that, from, and, this"
12890,"bats are also important reservoir species for a great 

range of coronaviruses","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.133333333,"species, a, of, coronaviruses"
12891,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.133333333,"the, of, and, in"
12892,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.133333333,"and, in, the, of"
12893,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.133333333,"from, animals, to, is"
12894,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.133333333,"a, was, that, the, and, to"
12895,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.133333333,"was, that, to, and"
12896,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.133333333,"the, to, known, be"
12897,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.133333333,"of, the, animal, as, possible, intermediate"
12898,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.133333333,"the, a, that, with, and, to"
12899,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.133333333,"the, that, with, of, and, to"
12900,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.133333333,"the, to, that, in, had, virus"
12901,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.133333333,"that, the, of, had, to, or"
12902,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.133333333,"the, of, market, in, wuhan, covid-19"
12903,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.133333333,"et, al., in, to, the, also, and, as"
12904,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.133333333,"that, of, from, to, an, is, coronavirus, the"
12905,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.133333333,"the, pangolin, was, and, that, a"
12906,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.133333333,"that, to, sars-cov-2, bats, and, from"
12907,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.133333333,"be, a, virus, from, to, bats, and, as"
12908,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.133333333,"that, the, sars-cov-2, and, from, bats"
12909,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.133333333,"that, sars-cov-2, the, virus, and, to"
12910,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.133333333,"to, the, from, a, recombinant, virus"
12911,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.133333333,"to, of, the, covid-19, virus, which, has, and"
12912,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.133333333,"a, virus, from, to, for, the"
12913,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.133333333,"the, of, a, and, has, bat"
12914,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.133333333,"of, that, the, covid-19, bat, a, from, for"
12915,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Bats have been reported as being the rich source of 

coronaviruses",0.133333333,"the, of, as, bats"
12916,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Bats have been reported as being the rich source of 

coronaviruses",0.133333333,"the, have, been, source"
12917,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Bats have been reported as being the rich source of 

coronaviruses",0.133333333,"the, of, bats, as"
12918,evidence suggests bats as its origin,"Bats have been reported as being the rich source of 

coronaviruses",0.133333333,"bats, as"
12919,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.133333333,"from, with, to, the"
12920,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.133333333,"has, the, to, sars-cov-2"
12921,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.133333333,"sars-cov-2, has, the, with"
12922,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.133333333,"of, sars-cov-2, humans, from, and, to"
12923,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.133333333,"the, of, from, and, with, sars-cov-2"
12924,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.133333333,"with, the, sars-cov-2, bat"
12925,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.133333333,"sars-cov-2, from, bat, ratg13"
12926,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.133333333,"virus, that, to, a"
12927,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.133333333,"sars-cov-2, a, virus, that"
12928,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.133333333,"sars-cov-2, has, a, to"
12929,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.133333333,"recombination, analysis, the, and"
12930,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.133333333,"of, the, is, to"
12931,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.133333333,"considered, possible, intermediate, the"
12932,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.133333333,"the, of, to, human"
12933,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.133333333,"the, is, of, human, and, one"
12934,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.133333333,"sars-cov-2, and, was, an, animal, humans"
12935,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.133333333,"bats, are, a, the, virus, and, in, to"
12936,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.133333333,"bats, are, and, the"
12937,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.133333333,"was, in, bats, and"
12938,"expended to make the simple point 

that COVID-19 had a natural origin.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.133333333,"to, the, that, covid-19"
12939,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.133333333,"believe, that, of, the"
12940,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.133333333,"the, virus, covid-19, has, of, which, to, and"
12941,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.133333333,"the, of, in, is, to, bats"
12942,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.133333333,"is, the, virus, to, in, covid-19"
12943,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.133333333,"that, covid-19, to, bats,"
12944,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.133333333,"the, of, as, was, a, at, that, virus"
12945,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.133333333,"the, of, a, was"
12946,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.133333333,"the, evidence, that, as"
12947,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.133333333,"the, was, that, as"
12948,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.133333333,"believe, that, naturally, the"
12949,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.133333333,"and, to, the, animal"
12950,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.133333333,"to, and, animal, in"
12951,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.133333333,"to, the, that, and"
12952,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.133333333,"is, to, the, in"
12953,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.133333333,"the, in, similar, to, that, animal"
12954,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.133333333,"the, with, and, bat"
12955,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.133333333,"the, and, zoonotic, that"
12956,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.133333333,"to, the, and, is, may, be"
12957,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.133333333,"the, virus, and, to"
12958,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.133333333,"zoonotic, and, be, to"
12959,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.133333333,"to, the, and, that, bats, be"
12960,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.133333333,"be, virus, the, and"
12961,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.133333333,"is, the, and, may, be, to"
12962,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.133333333,"the, of, is, human, bat, for, sars-cov, study"
12963,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.133333333,"the, of, bats, reservoir"
12964,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.133333333,"bats, are, the, natural, reservoir, of"
12965,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.133333333,"the, sars-cov-2, of, bat"
12966,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.133333333,"the, sars-cov, and, sars-cov-2, is, to"
12967,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.133333333,"a, the, sars-cov-2, that, sars-cov, and"
12968,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.133333333,"sars-cov-2, also, ace2, a, and, that, the, for"
12969,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.133333333,"that, the, for, a, sars-cov, and"
12970,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.133333333,"study, for, the, sars-cov, of, bat, is, human"
12971,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.133333333,"the, of, similar, to, sars-cov-2., is"
12972,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.133333333,"is, the, for, similar, to, bat"
12973,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.133333333,"from, the, reservoir, of"
12974,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.133333333,"it, that, the, of, majority, from"
12975,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.133333333,"of, the, been, that"
12976,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.133333333,"that, has, the, bat"
12977,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.133333333,"sars-cov-2, genetic, and, is, virus, that"
12978,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.133333333,"of, the, sars-cov-2, genome, that, and"
12979,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.133333333,"that, the, between, and, of, bat"
12980,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.133333333,"viruses, of, the, isolated, in, from"
12981,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.133333333,"which, the, its, in"
12982,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.133333333,"the, bats, covid-19, virus"
12983,Bats are hosts of many coronaviruses,Many of these CoVs can infect several animal species as well,0.133333333,"of, many"
12984,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.133333333,"is, a, virus, that"
12985,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.133333333,"to, that, a, from"
12986,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.133333333,"a, that, from, zoonotic"
12987,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.133333333,"a, to, that, virus"
12988,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.133333333,"is, from, animals, to"
12989,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.133333333,"the, virus, for, a, to, from"
12990,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.133333333,"the, is, to, from"
12991,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.133333333,"is, the, humans, from"
12992,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.133333333,"is, the, virus, to"
12993,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.133333333,"the, is, from, virus"
12994,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.133333333,"the, is, a, virus"
12995,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.133333333,"for, to, the, virus"
12996,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.133333333,"the, related, to, sars-cov-2"
12997,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.133333333,"bats, are, the, sars-cov-2"
12998,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.133333333,"from, to, closely, related, the, bats, are, sars-cov-2"
12999,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.133333333,"coronaviruses, of, in, bats"
13000,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.133333333,"the, is, in, of"
13001,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.133333333,"in, to, is, of, the, bats"
13002,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.133333333,"from, to, the, is"
13003,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.133333333,"and, in, been, the, from, animal"
13004,"zoonotic corona- 

viruses have become an increasing threat to human health,","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.133333333,"have, an, to, human"
13005,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.133333333,"origin, and, a, that"
13006,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.133333333,"is, that, or, natural"
13007,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.133333333,"that, sars-cov-2, has, and"
13008,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.133333333,"in, has, its, bats"
13009,evidence suggests bats as its origin,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.133333333,"bats, its"
13010,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.133333333,"from, humans, the, is"
13011,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.133333333,"the, sars-cov-2, from, and"
13012,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.133333333,"the, that, is, from"
13013,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.133333333,"and, that, the, sars-cov-2"
13014,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.133333333,"is, the, and, sars-cov-2"
13015,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.133333333,"of, sars-cov-2, that, and, is, to"
13016,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.133333333,"there, that, it, an, sars-cov-2, to, and, is"
13017,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.133333333,"this, in, and, the, virus, of"
13018,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",COVID-19 is a zoonotic virus,0.133333333,"virus, zoonotic"
13019,"expended to make the simple point 

that COVID-19 had a natural origin.",COVID-19 is a zoonotic virus,0.133333333,"covid-19, a"
13020,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",COVID-19 is a zoonotic virus,0.133333333,"covid-19, is"
13021,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.133333333,"the, of, from, reservoir"
13022,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.133333333,"in, many, such, and"
13023,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.133333333,"the, to, and, that"
13024,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.133333333,"sars-cov-2, the, coronaviruses, that, of, is"
13025,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.133333333,"the, identity, with, human"
13026,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.133333333,"zc45, and, from, to, related, that, the, of, coronavirus, very"
13027,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.133333333,"is, and, bat, the, between, that"
13028,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.133333333,"the, that, to, a, and, transmitted"
13029,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.133333333,"the, and, seafood, market, a, to"
13030,"civet cats and raccoon dogs  

are the intermediate hosts","the close relation  

between SARS coronavirus and 2019-nCoV",0.133333333,"and, the"
13031,"The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.133333333,"the, sources, direct, and"
13032,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.133333333,"on, in, hubei, and, identified, patients, at, seafood"
13033,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.133333333,"sars-cov-2, from, a, between, and, in, bat, china"
13034,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.133333333,"a, in, the, with, genome, of"
13035,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.133333333,"the, bat, isolated, from, in, china"
13036,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.133333333,"sars-cov-2, is, bat, in"
13037,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.133333333,"that, sars-cov-2, a, from"
13038,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.133333333,"this, is, a, in"
13039,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.133333333,"a, that, sars-cov-2, from"
13040,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.133333333,"a, that, sars-cov-2, virus"
13041,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.133333333,"from, that, in, sars-cov-2"
13042,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.133333333,"in, this, that, bat"
13043,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.133333333,"protein, analysis, that, of, were, in, intermediate, pangolin"
13044,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.133333333,"a, that, the, sars-cov-2, and, sars-cov"
13045,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.133333333,"the, sars-cov-2, and, of, genome, that"
13046,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.133333333,"sars-cov-2, a, genome, sars-cov"
13047,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.133333333,"sars-cov-2, that, nearly, and"
13048,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.133333333,"analysis, revealed, the, and"
13049,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.133333333,"the, and, sars-cov-2, of"
13050,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.133333333,"the, sars-cov-2, of, humans"
13051,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.133333333,"of, sars-cov-2, the, and"
13052,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.133333333,"of, the, sars-cov-2, and"
13053,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.133333333,"sars-cov-2, the, and, of"
13054,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.133333333,"sars-cov-2, of, animal, and, the, hosts"
13055,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.133333333,"and, hosts, sars-cov-2, humans, other, the"
13056,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.133333333,"bats, pangolins, are, hosts"
13057,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Bats are natural hosts of many of the known  

coronaviruses",0.133333333,"the, bats, hosts, of"
13058,The FCS of SARS-CoV-2 was not bioengineered—full stop.,"Bats are natural hosts of many of the known  

coronaviruses",0.133333333,"the, of"
13059,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.133333333,"from, that, sars-cov-2, to, a, bat, and, coronavirus"
13060,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.133333333,"96.2%, to, a, sequence, which, from, bat, in"
13061,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.133333333,"intermediate, as, to, this, was, the, of, that, suggested, may"
13062,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.133333333,"that, the, a, transmitted, to, and"
13063,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.133333333,"the, hypothesis, and, that, a, of"
13064,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.133333333,"after, the, of, virus, to, is"
13065,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.133333333,"that, the, of, and, has, been"
13066,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.133333333,"genome, a, with, the, of, in"
13067,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.133333333,"the, that, in, to"
13068,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.133333333,"coronavirus, with, to, in"
13069,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.133333333,"in, with, the, to, that, of, sars-, cov-2"
13070,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.133333333,"of, that, the, a"
13071,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.133333333,"with, the, sars-cov-2, of"
13072,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.133333333,"of, the, sars-cov-2, with"
13073,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.133333333,"and, identified, in, patients, at, seafood, hubei, on"
13074,"with the first case being linked to  

a seafood market","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.133333333,"the, linked, to, seafood"
13075,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.133333333,"of, the, cases, to, huanan, seafood"
13076,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.133333333,"of, the, scientific, supports"
13077,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.133333333,"the, of, sars-cov-2, a"
13078,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.133333333,"the, of, sars-cov-2, is, a, that"
13079,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.133333333,"the, data, that, is"
13080,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.133333333,"of, that, supports, the, is, a"
13081,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.133333333,"the, in, is, on"
13082,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.133333333,"bats, the, of, sars-cov-2"
13083,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.133333333,"a, the, was, to, in, sars-cov-2"
13084,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.133333333,"the, bat, to, closest, in, of"
13085,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.133333333,"horseshoe, bat, in, yunnan"
13086,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.133333333,"the, that, of, at"
13087,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.133333333,"a, that, and, was, the, pangolin"
13088,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.133333333,"the, hypothesis, that, a, of, and"
13089,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.133333333,"of, has, been, the"
13090,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.133333333,"sars-cov-2, the, and, from"
13091,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.133333333,"of, the, sars-cov-2, a"
13092,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.133333333,"of, the, origin, a, from, as"
13093,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.133333333,"a, of, and, pangolins, the, sars-cov-2"
13094,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.133333333,"the, sars-cov-2, to, in, of, sequence"
13095,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.133333333,"to, the, hypothesis, that, sars-cov-2, of"
13096,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.133333333,"in, related, that, the, closely, to"
13097,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.133333333,"sars-cov-2, ratg13, pangolin, to, the, of"
13098,The COVID-19 most likely developed from bat origin coronaviruses,"this one jumped from bats origin  

into humans",0.133333333,"from, origin"
13099,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.133333333,"to, a, coronavirus, the"
13100,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.133333333,"to, the, a, coronavirus"
13101,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.133333333,"to, human, rather, than"
13102,COVID-19 is a zoonotic virus,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.133333333,"zoonotic, virus"
13103,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.133333333,"have, to, a, as, studies, high, and, species"
13104,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.133333333,"and, species, to, the, evolution, of"
13105,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.133333333,"the, of, species, as, viruses, a, to, exchange"
13106,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.133333333,"the, in, of, bat"
13107,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.133333333,"in, the, of, and"
13108,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.133333333,"the, has, a, of, and, bat"
13109,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.133333333,"and, the, zoonotic, of"
13110,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.133333333,"this, that, bats, are, hosts, for"
13111,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.133333333,"the, of, to, and, reservoirs, sars-cov-2"
13112,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.133333333,"sars-cov-2, viruses, to, and"
13113,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.133333333,"it, bats, the, for, as, a"
13114,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.133333333,"a, to, has, sars-cov-2"
13115,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.133333333,"a, sars-cov-2, genome, sars-cov"
13116,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.133333333,"the, considered, possible, intermediate"
13117,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.133333333,"the, a, intermediate, host"
13118,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.133333333,"with, similarity, sars-cov-2, in"
13119,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.133333333,"in, a, for, sars-cov-2, were, with"
13120,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.133333333,"of, to, the, that, had, or"
13121,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.133333333,"sars-cov-2, is, that, to, the, pandemic"
13122,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.133333333,"is, sars-cov-2, to, the, viruses, that"
13123,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.133333333,"sars-cov-2, to, related, the"
13124,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.133333333,"in, the, that, to"
13125,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.133333333,"the, virus, for, and, to, in"
13126,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.133333333,"that, sars-cov-2, has, to, and, with"
13127,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.133333333,"the, an, is, to, that, of, coronavirus, from"
13128,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.133333333,"sars-cov-2, is, to, in, the, host, with, pangolin"
13129,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.133333333,"the, of, that, sars-cov-2, to, a, with, pangolin"
13130,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.133333333,"from, and, with, the, of, sars-cov-2"
13131,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.133333333,"of, sars-cov-2, genome, sequences, the, in"
13132,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.133333333,"virus, sars-cov-2, in, genome"
13133,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.133333333,"that, sars-cov-2, a, in"
13134,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.133333333,"in, yunnan, horseshoe, bat"
13135,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.133333333,"that, sars-cov-2, of, a"
13136,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.133333333,"virus, in, province, with, sars-cov-2, of"
13137,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.133333333,"has, that, sars-cov-2, in"
13138,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.133333333,"that, sars-cov-2, to, the"
13139,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.133333333,"from, the, nucleotide, with"
13140,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.133333333,"the, with, to, human"
13141,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.133333333,"the, has, to, sars-cov-2"
13142,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.133333333,"as, et, al., also, the, and, in, to"
13143,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","bats are also important reservoir species for a great 

range of coronaviruses",0.133333333,"coronaviruses, a, species, of"
13144,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.133333333,"to, sars-cov-2, from, of, in, bats, the, and"
13145,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.133333333,"the, species, of, bats, in, and"
13146,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.133333333,"bats, an, and, the, from, in"
13147,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.133333333,"the, from, nucleotide, with"
13148,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.133333333,"of, higher, with, than"
13149,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.133333333,"from, bats, to, is, and, the"
13150,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.133333333,"a, that, the, sars-cov-2, also, ace2, and, for"
13151,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.133333333,"the, of, sars-cov-2, animal, hosts, and"
13152,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.133333333,"the, be, to, that, between, humans, and, sars-cov-2"
13153,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.133333333,"the, sars-cov-2, hosts, and, other, humans"
13154,"This suggests that the BANAL series may be able to directly infect  

humans.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.133333333,"that, the, may, able, to, infect"
13155,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.133333333,"the, to, sars-cov-2, was, in, a"
13156,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.133333333,"from, an, host, to, a, as"
13157,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.133333333,"a, intermediate, host, the"
13158,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.133333333,"of, the, to, and, that, was"
13159,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.133333333,"of, cases, to, the, huanan, seafood"
13160,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.133333333,"the, animal, and, sars-cov-2, at, in"
13161,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.133333333,"the, sars-cov-2, and, to"
13162,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.133333333,"and, in, the, sars-cov-2"
13163,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.133333333,"the, of, that, market, in, this"
13164,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.133333333,"this, the, intermediate, host"
13165,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.133333333,"sars-cov-2, to, similarity, found, in, bat"
13166,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.133333333,"coronavirus, in, with, to"
13167,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.133333333,"sars-cov-2, similarity, with, in"
13168,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.133333333,"sars-cov-2, from, that, in"
13169,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.133333333,"in, from, of, bats, to, sars-cov-2, and, the"
13170,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.133333333,"to, the, been, in, bats, of, rhinolophus, and, that, a"
13171,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.133333333,"that, sars-cov-2, sequences, to, and, a, the, of"
13172,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.133333333,"it, that, the, majority, of, from"
13173,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.133333333,"the, covid-19, virus, in, to, of"
13174,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.133333333,"in, species, of, bats, and, the"
13175,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.133333333,"of, in, bats, the, horseshoe, china"
13176,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.133333333,"viral, and, of, the, most, likely"
13177,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.133333333,"the, in, bats, are, more, likely"
13178,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.133333333,"bats, the, for, as"
13179,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.133333333,"the, of, bats, and, as, for"
13180,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.133333333,"and, the, for, of"
13181,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.133333333,"bats, and, the, of, most, species"
13182,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.133333333,"the, of, sars-cov-2, likely, to, bat"
13183,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.133333333,"in, the, virus, for, to, and"
13184,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.133333333,"and, the, to, viruses, closely, related, other, in, for, virus"
13185,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.133333333,"the, closely, related, for, in, virus, to, sars"
13186,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.133333333,"for, the, and, were, virus, in, sars, to"
13187,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.133333333,"and, in, the, for, viruses, to"
13188,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.133333333,"in, bat, to, and"
13189,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.133333333,"the, evolution, of, to, and, species"
13190,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.133333333,"viruses, in, a, but, of, species"
13191,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.133333333,"the, of, to, a, exchange, species, as, viruses"
13192,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.133333333,"the, virus, for, and, other, viruses, closely, related, to, in"
13193,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.133333333,"the, similarity, sars-cov-2, bat, is, which"
13194,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.133333333,"the, was, in, and, to, other"
13195,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.133333333,"the, and, by, which, a, in"
13196,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.133333333,"in, the, was, a, at, to, both, and, closely, related"
13197,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.133333333,"by, in, the, are, with, other"
13198,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.133333333,"the, of, is, similar, to, sars-cov-2."
13199,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.133333333,"to, and, of, is, that, similar"
13200,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.133333333,"the, virus, for, sars, closely, related, to, in"
13201,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.133333333,"the, to, of, human"
13202,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.133333333,"the, to, with, human"
13203,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.133333333,"that, the, of, than"
13204,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","This suggests that the BANAL series may be able to directly infect  

humans.",0.133333333,"the, that, to, be"
13205,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","This suggests that the BANAL series may be able to directly infect  

humans.",0.133333333,"the, able, to, that, may, infect"
13206,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","This suggests that the BANAL series may be able to directly infect  

humans.",0.133333333,"this, be, that, the"
13207,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.133333333,"the, of, a, viruses"
13208,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.133333333,"the, site, and, which, have, to, a, is"
13209,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.133333333,"the, related, to, which, a, is"
13210,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.133333333,"the, is, virus, to, after, of"
13211,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.133333333,"and, was, bats, in"
13212,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.133333333,"the, sars-cov-2, is, in"
13213,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.133333333,"the, to, be, known"
13214,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.133333333,"in, to, is, the, covid-19, virus"
13215,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.133333333,"the, sars-cov-2, is, virus"
13216,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.133333333,"the, identified, that, spilled, over, humans, infected, and"
13217,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.133333333,"the, a, was, from, to, at, and, with"
13218,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.133333333,"with, the, for, of, suggesting, a, exposure, or, to, that, in, sars, animal, palm, by, market"
13219,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.133333333,"the, virus, for, sars, and, to, were, in"
13220,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.133333333,"to, a, of, an, and, later, adapted, the"
13221,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.133333333,"in, a, of, to, the, virus, that, was, from, were, found, as"
13222,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.133333333,"at, that, the, virus, was, as, of, a"
13223,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.133333333,"was, in, a, closely, related, and, both, to, at, the"
13224,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.133333333,"from, intermediate, as, and, to, was, the, of, that, adapted, in, a"
13225,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.133333333,"live, animal, at, markets, a, zoonotic, and, in, some, the, to, sars"
13226,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.133333333,"a, of, market, in, that, animal, for, sars, with, palm, by, the, suggesting, or, exposure, to"
13227,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.133333333,"the, is, that, of, covid-19, cases, associated, with, huanan, market, and, in, all, at"
13228,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.133333333,"the, a, seafood, market, to, and"
13229,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.133333333,"the, covid-19, and, to, seafood, of"
13230,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.133333333,"at, some, to, a, animal, in, the, markets, sars, live, zoonotic, and"
13231,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.133333333,"the, that, in, a, sars, and, to, epidemic"
13232,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.133333333,"the, is, one, of, and, human"
13233,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.133333333,"cases, associated, with, the, huanan, and, of, all, that, covid-19, in, is, at, market"
13234,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.133333333,"a, is, the, to, that, virus"
13235,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.133333333,"is, that, the, to, sars-cov-2, pandemic"
13236,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.133333333,"the, to, is, that, for, its"
13237,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.133333333,"the, to, for, a, is, most"
13238,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.133333333,"the, a, that, most, over, to, humans, infected"
13239,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.133333333,"the, that, sars-cov-2, with, virus, to"
13240,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","expended to make the simple point 

that COVID-19 had a natural origin.",0.133333333,"that, to, the, natural"
13241,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","expended to make the simple point 

that COVID-19 had a natural origin.",0.133333333,"a, that, the, had"
13242,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","expended to make the simple point 

that COVID-19 had a natural origin.",0.133333333,"the, covid-19, to, that"
13243,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","expended to make the simple point 

that COVID-19 had a natural origin.",0.133333333,"the, natural, to, that"
13244,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","expended to make the simple point 

that COVID-19 had a natural origin.",0.133333333,"that, the, a, covid-19"
13245,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","expended to make the simple point 

that COVID-19 had a natural origin.",0.133333333,"the, that, covid-19, to"
13246,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","expended to make the simple point 

that COVID-19 had a natural origin.",0.133333333,"covid-19, that, to, the"
13247,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.133333333,"and, sars-cov-2, related, to, coronaviruses, in"
13248,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.133333333,"were, sars-cov-2, from, in, and, to"
13249,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.133333333,"to, sars-cov-2, that, from, bats, and"
13250,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.",0.133333333,"and, the, sources, direct"
13251,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.133333333,"in, which, of, their"
13252,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.133333333,"sars-cov-2, or, a, in"
13253,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.133333333,"and, sars-cov-2, an, animal, was, humans"
13254,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.133333333,"the, that, sars-cov-2, protein, is, of"
13255,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.133333333,"of, the, or, most, evidence, natural"
13256,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.133333333,"of, sars-cov-2, that, is"
13257,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.133333333,"that, a, of, sars-cov-2"
13258,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.133333333,"of, that, sars-cov-2, is"
13259,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.133333333,"of, sars-cov-2, that, a"
13260,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.133333333,"that, of, sars-cov-2, is, laboratory, it"
13261,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.133333333,"virus, from, the, is"
13262,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.133333333,"is, that, the, from"
13263,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.133333333,"data, the, that, is"
13264,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.133333333,"is, that, its, to, the, for"
13265,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.133333333,"is, similarity, bat, to, the, that"
13266,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.133333333,"that, is, in, from, a, to"
13267,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.133333333,"to, bind, which, the, its, in"
13268,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.133333333,"the, of, that, to, in, this"
13269,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.133333333,"of, the, that, sars-cov-2, is, coronaviruses"
13270,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.133333333,"genome, the, covid-19, bat, showed, that"
13271,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.133333333,"a, and, in, the, that, to, sars, epidemic"
13272,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.133333333,"bats, the, of, and, more, than"
13273,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.133333333,"to, that, covid-19, bats,"
13274,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.133333333,"the, possible, intermediate, animal, of, as"
13275,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.133333333,"the, for, covid-19, a, of, that, from, bat"
13276,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.133333333,"of, supports, the, that, is, a"
13277,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.133333333,"the, origin, of, as, a, from"
13278,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.133333333,"the, virus, to, that, of, and"
13279,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.133333333,"the, covid-19, of, to, virus, in"
13280,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.133333333,"the, covid-19, and, seafood, of, to"
13281,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.133333333,"are, in, to, be"
13282,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.133333333,"believed, that, are, to"
13283,Many of these CoVs can infect several animal species as well,Bats are hosts of many coronaviruses,0.133333333,"many, of"
13284,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.133333333,"were, to, animal, in"
13285,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.133333333,"covid-19, is, to, the"
13286,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.133333333,"been, that, the, of"
13287,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.133333333,"in, the, of, was"
13288,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.133333333,"most, by, in, the"
13289,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.133333333,"the, was, in, that"
13290,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.133333333,"for, the, of, is, virus, and, that, to"
13291,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.133333333,"the, covid-19, is, to"
13292,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.133333333,"the, was, to, it, that, of"
13293,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.133333333,"the, was, to, bat"
13294,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.133333333,"to, a, of, in, rhinolophus, bats, the, and, been, that"
13295,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.133333333,"not, that, the, was, it, been"
13296,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.133333333,"the, that, of, has, not, been"
13297,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.133333333,"of, that, it, to, the, was"
13298,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.133333333,"the, of, horseshoe, bats, in, china"
13299,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.133333333,"that, natural, is, or"
13300,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.133333333,"the, isolated, from, bat, in, china"
13301,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.133333333,"to, the, from, is"
13302,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.133333333,"the, and, bats, from, is, to"
13303,"civet cats and raccoon dogs  

are the intermediate hosts","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.133333333,"civet, and, the, intermediate"
13304,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.133333333,"to, be, a, virus, from, bats, and, as"
13305,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.133333333,"on, and, they, can, are, to, bats, a, be, then"
13306,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.133333333,"are, to, be, in"
13307,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.133333333,"can, be, a, to, bats, and, are, they, then, on"
13308,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.133333333,"the, was, of, a"
13309,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.133333333,"of, the, in, was"
13310,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.133333333,"and, a, of, between, in, the"
13311,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.133333333,"of, the, in, viruses, isolated, from"
13312,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.133333333,"virus, in, province, of, with, sars-cov-2"
13313,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.133333333,"of, in, their, which"
13314,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.133333333,"in, an, from, bats, and, the"
13315,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.133333333,"the, and, a, that"
13316,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.133333333,"that, the, is, a"
13317,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.133333333,"related, to, a, the, which, is"
13318,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.133333333,"is, a, to, the, most, for"
13319,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.133333333,"spilled, over, humans, that, the, identified, and, infected"
13320,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.133333333,"a, that, humans, infected, to, the, most, over"
13321,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.133333333,"is, the, in, on"
13322,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.133333333,"a, virus, the, is"
13323,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.133333333,"is, the, virus, sars-cov-2"
13324,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.133333333,"that, a, of, virus, the, sars-cov-2"
13325,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","zoonotic corona- 

viruses have become an increasing threat to human health,",0.133333333,"have, human, an, to"
13326,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.133333333,"the, virus, for, of, to, and"
13327,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.133333333,"the, of, zoonotic, and"
13328,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.133333333,"of, virus, to, and, the, for"
13329,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.133333333,"the, with, coronavirus, bats,"
13330,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.133333333,"in, by, with, other, are, the"
13331,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.133333333,"most, the, in, by"
13332,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.133333333,"has, been, that, sars-cov-2"
13333,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.133333333,"sars-cov-2, the, of, that, have, been, to, it, from, genetically"
13334,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.133333333,"the, of, suggested, that, may, as, intermediate, was, to, this"
13335,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.133333333,"in, the, of, as, intermediate, was, a, that, from, to, and, adapted"
13336,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.133333333,"not, the, was, of"
13337,"Bats are natural hosts of many of the known  

coronaviruses",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.133333333,"of, the"
13338,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.133333333,"that, in, has, sars-cov-2"
13339,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.133333333,"sars-cov-2, has, been, that"
13340,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.133333333,"the, be, to, sars-cov-2"
13341,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.133333333,"to, the, bat, was"
13342,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.133333333,"the, of, that, is, likely, origin"
13343,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.133333333,"the, most, likely, viral, of, and"
13344,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.133333333,"it, is, that, sars-cov-2, laboratory, of"
13345,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.133333333,"and, has, been, natural, of, origin"
13346,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.133333333,"a, in, receptor, binding, which, is, an, the"
13347,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",SARS-CoV-2 was created from SARS-CoV-2,0.133333333,"from, sars-cov-2"
13348,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.133333333,"to, that, sars-cov-2, from"
13349,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.133333333,"to, and, that, was"
13350,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.133333333,"to, that, sars-cov-2, and"
13351,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.133333333,"sars-cov-2, to, viruses, and"
13352,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.133333333,"sars-cov-2, and, from, ratg13"
13353,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.133333333,"sars-cov-2, and, ratg13, to"
13354,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.133333333,"with, higher, than, of"
13355,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.133333333,"evidence, that, the, as"
13356,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.133333333,"that, from, the, and, this, is"
13357,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.133333333,"sars-cov-2, the, genetic, of, to, coronaviruses"
13358,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.133333333,"ratg13, from, bat, sars-cov-2"
13359,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.133333333,"the, which, its, in"
13360,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.133333333,"to, its, in, the, which, bind"
13361,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.133333333,"the, sars-cov-2, that, bats, hosts, for"
13362,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.133333333,"sars-cov-2, a, and, from, bat, to, that, coronavirus"
13363,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.133333333,"that, the, sars-cov-2, and, bat, pangolin"
13364,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.133333333,"bats, are, hosts, pangolins"
13365,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.133333333,"the, bats, are, also"
13366,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.133333333,"the, virus, covid-19, bats"
13367,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.133333333,"the, that, in, a, genome, to, from, market"
13368,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.133333333,"the, of, at, that, is, a, virus, in"
13369,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.133333333,"the, is, similar, to, bat, for"
13370,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.133333333,"the, bats, as, a, for, it"
13371,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.133333333,"bats, as, the, for"
13372,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.133333333,"that, are, believed, to"
13373,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.133333333,"to, sars-cov-2, as, the"
13374,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.133333333,"to, it, is, that, similar, bat"
13375,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.133333333,"the, that, to, a, bat, and"
13376,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.133333333,"the, sequences, of, in, sars-cov-2, genome"
13377,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.133333333,"the, of, sars-cov-2, a, bat, genome"
13378,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.133333333,"the, of, at, sars-cov-2, a, in"
13379,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.133333333,"a, sequence, from, bat, to, 96.2%, which, in"
13380,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.133333333,"found, genome, sequences, to, a, of"
13381,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.133333333,"is, an, a, which, the, in, receptor, binding"
13382,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.133333333,"sars-cov-2, a, between, the, and, an"
13383,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.133333333,"and, to, covs, in, of, genome"
13384,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.133333333,"to, have, with, the, of, and, may, virus"
13385,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.133333333,"the, of, sars-cov-2, a, pangolins, and"
13386,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.133333333,"of, the, that, sars-cov-2, a, virus"
13387,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.133333333,"the, sars-cov-2, as, to"
13388,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.133333333,"the, of, that, believe"
13389,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.133333333,"the, believe, that, naturally"
13390,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.133333333,"the, that, of, is"
13391,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.133333333,"of, that, is, the"
13392,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.133333333,"that, the, and, bats, be, to"
13393,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.133333333,"the, within, sars-cov-2, at, than, that"
13394,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.133333333,"and, that, from, the, coronavirus, of"
13395,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.133333333,"sars-cov-2, that, from, bats, and, the"
13396,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.133333333,"the, that, of, and, has, been"
13397,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.133333333,"the, of, that, sars-cov-2, more, likely"
13398,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.133333333,"the, between, sars-cov-2, and, to, is, in, bat"
13399,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.133333333,"the, that, bat, and, similarity, to"
13400,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.133333333,"is, that, the, viruses, to, sars-cov-2"
13401,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.133333333,"the, similarity, to, bat, is, that"
13402,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.133333333,"the, that, sars-cov-2, and, similarity, to"
13403,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.133333333,"to, host, is, in, pangolin, with, sars-cov-2, the"
13404,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.133333333,"in, the, with, that, to, of, sars-, cov-2"
13405,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.133333333,"this, origin, of, the"
13406,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.133333333,"this, the, of, bat"
13407,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.133333333,"bat, pangolin, the, of"
13408,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.133333333,"bats, that, are, hosts, for, this"
13409,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.133333333,"the, likely, are, more, bats, in"
13410,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.133333333,"this, the, for, sars-cov-2"
13411,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.133333333,"bat, similarity, is, which, sars-cov-2, the"
13412,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.133333333,"the, that, sars-cov-2, bat, and, pangolin"
13413,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.133333333,"the, has, with, sars-cov-2"
13414,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.133333333,"has, that, the, bat"
13415,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.133333333,"that, sars-cov-2, has, with"
13416,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.133333333,"the, sars-cov-2, same, with"
13417,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.133333333,"the, that, bat, origin"
13418,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.133333333,"that, the, sars-cov-2, or"
13419,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.133333333,"sars-cov-2, are, bats, the"
13420,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.133333333,"sars-cov-2, bats, the, of"
13421,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.133333333,"on, the, of, that, to, origin"
13422,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.133333333,"to, sars-cov-2, a, of, sequences, the, and, that"
13423,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.133333333,"of, sequences, to, a, genome, found"
13424,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.133333333,"that, of, to, a, pangolin, with, sars-cov-2, the"
13425,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.133333333,"the, likely, to, of, sars-cov-2, bat"
13426,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.133333333,"that, the, of, sars-cov-2, more, likely"
13427,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.133333333,"that, sars-cov-2, the, with, of, to"
13428,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.133333333,"to, that, sars-cov-2, has, with, and"
13429,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.133333333,"to, with, the, of, and, sars-cov"
13430,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.133333333,"to, sars-cov-2, and, the"
13431,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.133333333,"of, with, to, and, the, sars-cov-2"
13432,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.133333333,"the, with, sars-cov-2, is"
13433,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.133333333,"the, of, is, sars-cov-2, with, and"
13434,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.133333333,"sars-cov-2, the, same, with"
13435,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.133333333,"identity, sars-cov-2, sars-cov, with, the, of"
13436,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.133333333,"analysis, the, recombination, and"
13437,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.133333333,"analysis, the, revealed, and"
13438,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.133333333,"the, of, and, that, sars-cov-2, in"
13439,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.133333333,"that, sars-cov-2, the, and"
13440,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.133333333,"sars-cov-2, and, in, the"
13441,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.133333333,"the, of, that, have, and, including"
13442,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.133333333,"a, that, the, and, for, sars-cov"
13443,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.133333333,"with, sars-cov, and, sars-cov-2, sars-like, covs"
13444,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.133333333,"the, sars-cov-2, recombinant, and"
13445,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.133333333,"in, the, are, to"
13446,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.133333333,"in, and, to, the"
13447,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.133333333,"sars-cov-2, to, the, in"
13448,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.133333333,"and, this, virus, the, in, of"
13449,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.133333333,"sars-cov-2, virus, that, with, to, the"
13450,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.133333333,"similarity, sars-cov-2, and, to, the, that"
13451,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.133333333,"the, between, and, of, that, bat"
13452,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.133333333,"that, in, this, bat"
13453,"This suggests that the BANAL series may be able to directly infect  

humans.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.133333333,"this, that, the, be"
13454,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.133333333,"this, the, bat, of"
13455,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.133333333,"is, the, to, that, in, virus"
13456,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.133333333,"the, this, intermediate, host"
13457,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.133333333,"to, a, recombinant, virus, from, the"
13458,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.133333333,"in, the, that, was, first, for, as, sars-cov-2."
13459,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.133333333,"that, the, was, as"
13460,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.133333333,"the, in, that, was"
13461,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.133333333,"that, the, origin, bat"
13462,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.133333333,"sars-cov-2, that, is, to"
13463,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.133333333,"the, of, that, most"
13464,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.133333333,"that, the, of, most"
13465,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.133333333,"the, virus, and, be"
13466,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.133333333,"and, a, between, sars-cov-2, an, the"
13467,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.133333333,"a, at, in, that, the, virus, is, of"
13468,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.133333333,"a, of, sars-cov-2, at, the, in"
13469,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.133333333,"were, a, for, sars-cov-2, with, in"
13470,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",evidence suggests bats as its origin,0.133333333,"its, bats"
13471,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.133333333,"the, similar, to, that, in, animal"
13472,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.133333333,"sars-cov-2, from, to, are, closely, related, bats, the"
13473,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.133333333,"the, of, coronavirus, that, from, very, to, zc45, and, related"
13474,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.133333333,"the, to, in, of, is, be"
13475,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.133333333,"the, closest, to, in, of, bat"
13476,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.133333333,"of, that, and, is, to, bat"
13477,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.133333333,"of, and, similar, to, is, that"
13478,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.133333333,"it, is, that, similar, to, bat"
13479,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.133333333,"the, of, sars-cov-2, to, ratg13, pangolin"
13480,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.133333333,"sars-cov-2, to, ratg13, and"
13481,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.133333333,"is, that, sars-cov-2, a, laboratory, the"
13482,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.133333333,"sars-cov-2, is, a, the"
13483,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.133333333,"the, a, sars-cov-2, is"
13484,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.133333333,"is, that, sars-cov-2, a, the, or"
13485,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.133333333,"a, that, the, is"
13486,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.133333333,"that, sars-cov-2, the, or"
13487,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.132743363,"early, cases, with, the, huanan, and, of, a, exposure, to, were, covid-19, in, other, market"
13488,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.132743363,"of, cases, covid-19, with, a, exposure, to, early, other, and, the, huanan, market, were, in"
13489,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.132653061,"a, for, the, of, virus, and, in, that, ability, to, ace2, an, cells"
13490,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.132653061,"of, for, cells, to, ace2, a, virus, that, in, an, and, ability, the"
13491,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.132653061,"that, the, animal, into, humans, case, coupled, with, early, cases, of, in, at"
13492,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.132653061,"cases, with, the, huanan, and, of, a, to, that, were, in, market, majority"
13493,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.132653061,"the, of, animal, coupled, with, case, early, cases, that, into, humans, at, in"
13494,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.132653061,"that, the, majority, of, cases, were, in, to, with, a, and, huanan, market"
13495,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.13253012,"that, the, in, was, to, middle, east, respiratory, syndrome, animals, a"
13496,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.13253012,"in, the, a, middle, east, respiratory, syndrome, was, that, animals, to"
13497,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.13253012,"that, are, the, sars-cov-2, these, with, structure, consistent, hypothesis, of, natural"
13498,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.13253012,"the, that, these, are, consistent, with, of, natural, structure, sars-cov-2, hypothesis"
13499,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.132450331,"the, wildlife, live, from, and, were, in, by, after, of, a, as, to, data, that, positive, infected, at, least, virus"
13500,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.132450331,"in, after, the, live, of, from, that, positive, as, at, virus, to, data, least, wildlife, were, infected, by, a, and"
13501,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.132352941,"some, coronaviruses, to, sars-cov-2, in, the, spike, is, of"
13502,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.132352941,"a, by, from, was, in, that, the, virus, is"
13503,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.132352941,"with, the, of, bats, as, a, host, for, and"
13504,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.132352941,"that, the, from, a, market, live, in, transmitted, to"
13505,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.132352941,"analysis, that, the, covid-19, virus, in, transmitted, to, of"
13506,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.132352941,"and, be, for, transmission, to, the, key, rbd, with"
13507,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.132352941,"from, and, not, by, the, that, sars-cov-2, a, laboratory"
13508,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.132352941,"in, a, to, the, that, transmitted, from, live, market"
13509,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.132352941,"the, identified, a, of, that, most, likely, from, hosts"
13510,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.132352941,"and, a, of, ratg13, in, the, genomes, viruses, to"
13511,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.132352941,"of, that, only, had, the, reported, suggesting, transmission, to"
13512,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.132352941,"in, the, of, an, was, a, from, to, sample"
13513,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.132352941,"bats, a, for, as, the, of, and, with, host"
13514,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.132352941,"the, and, has, a, in, to, that, not, of"
13515,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.132352941,"a, of, sars-cov-2, in, is, an, the, to, 2"
13516,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.132352941,"by, from, at, in, the, is, to, found, bats"
13517,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.132352941,"the, key, to, be, with, rbd, for, transmission, and"
13518,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.132352941,"a, genome, from, at, that, the, virus, is, of"
13519,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.132352941,"only, of, reported, to, the, suggesting, that, transmission, had"
13520,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.132352941,"intermediate, host, species, and, humans, found, in, the, palm"
13521,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.132352941,"the, to, was, in, from, an, sample, of, a"
13522,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.132352941,"the, sars-cov-2, spike, some, to, of, is, in, coronaviruses"
13523,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.132352941,"and, a, of, in, receptor, the, viruses, to, human"
13524,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.132352941,"in, of, to, the, virus, that, covid-19, transmitted, analysis"
13525,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.132352941,"and, can, contact, with, to, or, bats, cave, be"
13526,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.132352941,"the, and, intermediate, host, species, palm, found, in, humans"
13527,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.132352941,"to, or, can, be, contact, with, and, cave, bats"
13528,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.132352941,"identified, the, of, a, from, that, most, likely, hosts"
13529,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.132352941,"the, by, that, sars-cov-2, and, not, from, a, laboratory"
13530,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.132352941,"on, the, by, in, receptor, binding, spike, protein, a"
13531,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.132352941,"is, that, was, from, a, by, the, virus, in"
13532,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.132352941,"at, the, in, found, bats, from, is, to, by"
13533,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.132352941,"is, that, a, the, of, virus, at, genome, from"
13534,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.132352941,"the, of, and, a, in, genomes, ratg13, viruses, to"
13535,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.132352941,"of, to, an, is, a, in, sars-cov-2, the, 2"
13536,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.132352941,"the, of, viruses, in, a, receptor, human, and, to"
13537,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.132352941,"a, on, the, in, receptor, binding, spike, protein, by"
13538,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.132352941,"in, the, of, is, to, sars-cov-2, that, pangolin, cov"
13539,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.132352941,"in, the, to, that, sars-cov-2, is, of, cov, pangolin"
13540,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.132352941,"in, the, of, not, to, that, has, and, a"
13541,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.132075472,"are, ., in, to, which, genetic, and"
13542,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.132075472,"the, and, of, bat, to, human, emergence"
13543,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.132075472,"the, virus, which, to, of, and, from"
13544,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.132075472,"to, virus, from, and, humans,, possibly, the"
13545,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.132075472,"other, coronaviruses, the, which, to, of, and"
13546,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.132075472,"the, of, sars-cov-2, and, is, to, bat"
13547,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.132075472,"the, by, that, sars-cov-2, from, a, laboratory"
13548,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.132075472,"to, the, emergence, of, and, bat, human"
13549,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.132075472,"the, and, suggesting, that, sars-cov-2, was, to"
13550,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.132075472,"in, the, a, was, that, to, and"
13551,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.132075472,"are, of, the, has, shown, bats, and"
13552,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.132075472,"that, been, by, of, and, are, the"
13553,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.132075472,"the, and, which, to, of, other, coronaviruses"
13554,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.132075472,"the, sars-cov-2, and, to, of, is, bat"
13555,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.132075472,"a, the, to, that, in, and, was"
13556,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.132075472,"the, coronaviruses, to, that, are, in, and"
13557,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.132075472,"to, the, in, evidence, bats, pangolins, be"
13558,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.132075472,"the, by, in, and, that, originated, a"
13559,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.132075472,"that, sars-cov-2, has, with, at, and, to"
13560,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.132075472,"studies, found, sars-cov-2, are, to, and, a"
13561,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.132075472,"the, of, that, coronavirus, from, and, bat"
13562,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.132075472,"that, the, of, bat, viruses, a, to"
13563,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.132075472,"of, at, the, a, to, indicating, that"
13564,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.132075472,"the, to, be, of, transmission, and, infection"
13565,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.132075472,"at, of, sars-cov-2, into, humans, in, and"
13566,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.132075472,"the, of, at, that, sars-cov-2, in, animal"
13567,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.132075472,"of, and, sars-cov-2, into, humans, at, in"
13568,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.132075472,"the, of, that, was, to, and, more"
13569,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.132075472,"the, that, of, covid-19, cases, huanan, and"
13570,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.132075472,"the, from, an, animal, in, market, and"
13571,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.132075472,"a, the, on, as, bat, and, with"
13572,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.132075472,"in, a, of, were, to, with, that"
13573,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.132075472,"to, the, of, and, which, from, virus"
13574,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.132075472,"that, the, is, a, from, as, intermediate"
13575,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.132075472,"and, that, from, the, bat, coronavirus, of"
13576,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.132075472,"the, of, that, a, virus, has, for"
13577,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.132075472,"analysis, suggested, the, recombination, to, of, and"
13578,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.132075472,"that, the, of, sars-cov-2, and, genetic, analysis"
13579,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.132075472,"comparative, that, the, of, sars-cov-2, and, a"
13580,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.132075472,"the, was, to, and, suggesting, that, sars-cov-2"
13581,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.132075472,"that, the, of, suggesting, have, to, an"
13582,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.132075472,"the, to, have, that, in, people, animals"
13583,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.132075472,"., and, are, to, in, genetic, which"
13584,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.132075472,"has, shown, bats, and, are, the, of"
13585,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.132075472,"the, covid-19, is, of, to, virus, in"
13586,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.132075472,"that, the, virus, is, to, of, bats"
13587,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.132075472,"on, the, as, a, with, bat, and"
13588,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.132075472,"as, the, of, a, high, human, bat"
13589,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.132075472,"the, bat, coronavirus, that, a, but, not"
13590,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.132075472,"confirmed, the, sars-cov-2, and, is, to, that"
13591,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.132075472,"a, is, to, the, which, that, it"
13592,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.132075472,"the, to, be, infection, and, of, transmission"
13593,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.132075472,"analysis, of, to, suggested, the, recombination, and"
13594,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.132075472,"analysis, of, genetic, that, sars-cov-2, the, and"
13595,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.132075472,"confirmed, that, the, sars-cov-2, and, to, is"
13596,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.132075472,"the, of, sequence, that, sars-cov-2, to, virus"
13597,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.132075472,"in, the, market, from, an, animal, and"
13598,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.132075472,"genome, from, the, virus, to, of, bats"
13599,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.132075472,"sars-cov-2, is, sequence, coronaviruses, to, that, coronavirus"
13600,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.132075472,"more, of, the, to, and, that, was"
13601,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.132075472,"of, that, the, to, bat, and, sars"
13602,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.132075472,"that, sars-cov-2, from, a, laboratory, by, the"
13603,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.132075472,"by, a, other, and, sars-cov-2, the, genome"
13604,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.132075472,"that, first, seafood, market, and, in, at"
13605,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.132075472,"sequence, that, sars-cov-2, coronavirus, is, to, coronaviruses"
13606,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.132075472,"a, comparative, of, that, sars-cov-2, the, and"
13607,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.132075472,"studies, that, the, a, of, sars-cov, and"
13608,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.132075472,"and, the, of, to, et, al.,, sars-cov-2"
13609,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.132075472,"an, a, the, bat, ratg13,, in, from"
13610,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.132075472,"the, sars-cov-2, of, sequence, virus, to, that"
13611,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.132075472,"the, by, coronavirus, rather, than, a, laboratory"
13612,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.132075472,"viruses, to, and, have, a, the, which"
13613,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.132075472,"these, are, to, that, bats, hosts, for"
13614,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.132075472,"the, of, sars-cov-, from, with, a, and"
13615,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.132075472,"a, the, as, of, bat, high, human"
13616,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.132075472,"that, the, virus, in, and, to, of"
13617,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.132075472,"found, the, of, homology, to, sars-cov-2, in"
13618,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.132075472,"study, the, host, of, sars-cov-2, an, intermediate"
13619,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.132075472,"of, to, found, in, homology, sars-cov-2, the"
13620,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.132075472,"sars-cov-2, et, al.,, and, to, the, of"
13621,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.132075472,"the, of, a, in, species, that, with, as, intermediate, and, or, also, ace2, for"
13622,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.132075472,"of, and, by, possible, between, species, the"
13623,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.132075472,"the, that, of, market, sequences, in, at"
13624,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.132075472,"in, to, is, of, the, covid-19, virus"
13625,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.132075472,"in, the, that, coronaviruses, are, to, and"
13626,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.132075472,"the, of, species, possible, and, between, by"
13627,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.132075472,"a, viruses, to, bat, that, the, of"
13628,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.132075472,"the, other, genome, by, sars-cov-2, and, a"
13629,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.132075472,"and, was, in, by, closely, related, the"
13630,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.132075472,"a, sars-cov-2, by, genome, at, the, in"
13631,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.132075472,"have, the, to, a, and, which, viruses"
13632,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.132075472,"also, ace2, in, a, of, species, and, that, the, with, as, or, intermediate, for"
13633,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.132075472,"the, of, to, is, natural, a, evidence"
13634,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.132075472,"of, evidence, the, covid-19, is, origin, a"
13635,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.132075472,"of, the, covid-19, cases, huanan, and, that"
13636,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.132075472,"that, first, and, in, at, seafood, market"
13637,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.132075472,"the, of, sequences, in, market, that, at"
13638,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.132075472,"of, the, in, and, that, sequences, with"
13639,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.132075472,"that, sequences, are, also, and, the, of"
13640,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.132075472,"the, is, of, evidence, a, natural, to"
13641,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.132075472,"the, of, that, sars-cov-2, likely, to, a"
13642,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.132075472,"the, that, of, is, it, as, for"
13643,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.132075472,"a, it, that, the, to, which, is"
13644,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.132075472,"is, that, the, of, to, sars-cov-2, coronaviruses"
13645,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.132075472,"the, shows, that, sars-cov-2, of, similarity, to"
13646,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.132075472,"of, the, in, similar, to, that, can"
13647,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.132075472,"with, the, of, a, sars-cov-, from, and"
13648,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.132075472,"is, we, sars-cov-2, and, the, that, in"
13649,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.132075472,"in, the, rbd, of, is, sars-cov-2, that"
13650,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.132075472,"a, the, coronavirus, bat, that, not, but"
13651,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.132075472,"to, the, of, bats, and, more, than"
13652,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.132075472,"is, a, that, from, the, as, intermediate"
13653,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.132075472,"the, covid-19, is, of, evidence, a, origin"
13654,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.132075472,"in, the, of, virus, to, that, and"
13655,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.132075472,"that, natural, in, and, the, for, of"
13656,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.132075472,"have, that, the, in, to, people, animals"
13657,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.132075472,"was, in, by, closely, related, and, the"
13658,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.132075472,"that, been, a, with, ratg13,, and, sars-cov-2"
13659,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.132075472,"the, that, has, at, of, virus, to"
13660,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.132075472,"the, of, it, is, that, as, for"
13661,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.132075472,"ratg13,, the, in, from, an, a, bat"
13662,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.132075472,"is, that, the, virus, bats, of, to"
13663,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.132075472,"from, genome, bats, to, the, of, virus"
13664,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.132075472,"the, of, that, to, bat, and, sars"
13665,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.132075472,"in, by, a, sars-cov-2, at, the, genome"
13666,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.132075472,"been, that, and, are, the, of, by"
13667,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.132075472,"been, with, ratg13,, that, and, sars-cov-2, a"
13668,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.132075472,"the, and, by, a, that, originated, in"
13669,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.132075472,"the, coronavirus, by, rather, than, a, laboratory"
13670,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.132075472,"the, that, of, with, and, sequences, in"
13671,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.132075472,"to, sars-cov-2, is, bat, cov, ratg13, pangolin"
13672,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.132075472,"the, to, bats, pangolins, evidence, in, be"
13673,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.132075472,"bats, to, that, these, are, hosts, for"
13674,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.132075472,"we, sars-cov-2, the, and, in, that, is"
13675,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.132075472,"bat, cov, and, the, sars-cov-2, ratg13, guangdong"
13676,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.132075472,"sars-cov-2, and, bat, cov, ratg13, guangdong, the"
13677,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.132075472,"the, of, more, than, to, and, bats"
13678,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.132075472,"sars-cov-2, to, a, are, studies, and, found"
13679,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.132075472,"the, that, of, are, and, sequences, also"
13680,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.132075472,"the, of, sars-cov-2, to, likely, a, that"
13681,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.132075472,"studies, that, the, of, and, sars-cov, a"
13682,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.132075472,"that, the, natural, of, and, in, for"
13683,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.132075472,"that, sars-cov-2, with, has, and, at, to"
13684,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.132075472,"similarity, to, sars-cov-2, the, shows, that, of"
13685,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.132075472,"of, the, at, has, that, to, virus"
13686,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.132075472,"sars-cov-2, the, rbd, in, that, of, is"
13687,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.132075472,"study, of, an, intermediate, host, sars-cov-2, the"
13688,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.132075472,"the, of, animal, that, sars-cov-2, at, in"
13689,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.132075472,"the, virus, for, has, a, of, that"
13690,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.132075472,"that, of, were, in, to, with, a"
13691,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.132075472,"a, at, to, indicating, that, the, of"
13692,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.132075472,"the, in, of, similar, to, that, can"
13693,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.132075472,"the, of, have, suggesting, that, an, to"
13694,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.131868132,"that, infected, from, bats, in, the, china, market, a, at, animals, and"
13695,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.131868132,"that, a, recombination, of, virus, with, similar, to, and, are, the, for"
13696,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.131868132,"live, animal, at, a, zoonotic, this, association, in, the, that, to, sars"
13697,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.131868132,"in, the, of, palm, sars, a, that, virus, to, civet, closely, related"
13698,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.131868132,"a, of, in, that, sars, palm, civet, the, to, virus, closely, related"
13699,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.131868132,"that, the, in, bats, and, from, infected, animals, at, a, market, china"
13700,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.131868132,"this, association, that, sars, a, zoonotic, the, animal, in, at, to, live"
13701,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.131868132,"and, the, of, to, similar, are, a, with, that, for, recombination, virus"
13702,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.131578947,"in, closely, related, to, coronaviruses"
13703,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.131578947,"closely, related, to, sars-cov-2, in"
13704,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.131578947,"are, to, and, the, of"
13705,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.131578947,"sars-cov-2., and, bat, to, in"
13706,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.131578947,"similar, to, the, sars-like, and"
13707,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.131578947,"that, sars-cov-2, a, of, origin"
13708,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.131578947,"a, of, that, sars-cov-2, by"
13709,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.131578947,"a, of, available, to, has, that, sars-cov-2, the, and, virus"
13710,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.131578947,"and, that, the, emergence, of"
13711,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.131578947,"the, genome, to, bat, that"
13712,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.131578947,"the, sars-cov-2, genome, with, that"
13713,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.131578947,"and, natural, origin, of, virus"
13714,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.131578947,"genome, and, on, origin, of"
13715,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.131578947,"tion, of, sars-cov-2, and, relatives"
13716,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.131578947,"the, sars-cov-2, in, and, mers-cov"
13717,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.131578947,"that, a, in, has, of"
13718,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.131578947,"of, has, that, the, a"
13719,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.131578947,"that, bats, the, as, a"
13720,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.131578947,"of, the, bats, are, reservoirs"
13721,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.131578947,"and, a, to, the, coronavirus, bats, be, of, with, as"
13722,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.131578947,"the, that, and, is, to"
13723,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.131578947,"that, in, the, virus, was"
13724,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.131578947,"the, sequence, that, and, is"
13725,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.131578947,"the, and, to, is, that"
13726,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.131578947,"is, that, the, to, a"
13727,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.131578947,"sars-cov-2, to, bats, the, of"
13728,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.131578947,"the, origin, zoonotic, that, in"
13729,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.131578947,"seafood, wholesale, in, wuhan,, and"
13730,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.131578947,"to, and, the, of, sars-cov-2"
13731,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.131578947,"the, of, sars-cov-2, and, coronavirus"
13732,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.131578947,"to, the, of, transmission, a"
13733,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.131578947,"t, that, the, species, and"
13734,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.131578947,"the, of, bats, natural, and"
13735,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.131578947,"genomic, sars-cov-2, only, through, the"
13736,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.131578947,"the, sequence, of, identity, sars-cov"
13737,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.131578947,"the, sars-cov-2, with, at, of"
13738,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.131578947,"the, in, is, to, from"
13739,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.131578947,"the, coronaviruses, to, and, including"
13740,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.131578947,"the, humans, from, through, in"
13741,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.131578947,"the, from, in, markets, china"
13742,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.131578947,"the, is, of, sars-cov-2, in"
13743,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.131578947,"sars-cov-2, is, in, the, bat"
13744,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.131578947,"the, of, that, sars-cov-2, bat"
13745,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.131578947,"is, the, to, that, and"
13746,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.131578947,"that, sars-cov-2, and, the, genome"
13747,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.131578947,"that, the, and, bat, is"
13748,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.131578947,"to, and, genome, the, sars-cov-2"
13749,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.131578947,"bats, are, the, reservoirs, of"
13750,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","civet cats and raccoon dogs  

are the intermediate hosts",0.131578947,"and, are, the, intermediate, hosts"
13751,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.131578947,"the, are, of, bats, and"
13752,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.131578947,"the, in, humans, through, from"
13753,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.131578947,"has, been, the, of, from"
13754,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.131578947,"in, be, to, humans, through"
13755,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.131578947,"the, conclusive, evidence, from, be"
13756,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.131578947,"the, that, in, zoonotic, origin"
13757,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.131578947,"the, and, that, a, one"
13758,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.131578947,"a, that, by, the, virus"
13759,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.131578947,"that, a, origin, of, sars-cov-2"
13760,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.131578947,"the, that, of, origin, a"
13761,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.131578947,"the, evidence, from, that, to"
13762,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.131578947,"sars-cov-2, the, only, through, genomic"
13763,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.131578947,"the, genome, sars-cov-2, that, and"
13764,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.131578947,"that, natural, selection, and, the"
13765,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.131578947,"the, of, from, and, ratg13"
13766,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.131578947,"sars-cov-2, from, closely, related, bats"
13767,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.131578947,"that, from, the, indicating, this"
13768,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.131578947,"are, viruses, to, the, that"
13769,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.131578947,"sars-cov-2, to, the, lineage, of"
13770,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.131578947,"of, at, the, huanan, market"
13771,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.131578947,"sars-cov-2, the, for, zoonotic, of"
13772,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.131578947,"that, of, to, and, infection"
13773,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.131578947,"are, and, the, to, market"
13774,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.131578947,"the, of, through, to, that"
13775,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.131578947,"the, to, that, animals, and"
13776,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.131578947,"the, that, to, and, animals"
13777,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.131578947,"of, that, to, the, and"
13778,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.131578947,"lineage, a, the, huanan, market"
13779,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.131578947,"the, huanan, market, that, in"
13780,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.131578947,"the, more, to, that, in"
13781,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.131578947,"the, more, closely, related, to"
13782,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.131578947,"the, of, at, huanan, market"
13783,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.131578947,"and, the, a, market, in"
13784,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.131578947,"the, of, origin, is, a"
13785,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.131578947,"the, of, origin, a, and"
13786,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.131578947,"a, the, lineage, huanan, market"
13787,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.131578947,"a, of, by, the, virus"
13788,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.131578947,"from, the, market, presence, of"
13789,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.131578947,"to, the, viruses, in, reservoirs"
13790,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.131578947,"viruses, in, reservoirs, to, the"
13791,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.131578947,"the, and, mers-cov, sars-cov-2, in"
13792,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.131578947,"in, that, the, huanan, market"
13793,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.131578947,"sars-cov-2, the, in, reservoirs, and"
13794,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.131578947,"the, market, that, in, sars-cov-2"
13795,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.131578947,"that, the, reservoir, and, mers-cov"
13796,"All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.131578947,"intel-, ligence, that, a, sars-cov-2"
13797,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.131578947,"a, intel-, ligence, that, sars-cov-2"
13798,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.131578947,"that, were, the, huanan, and"
13799,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.131578947,"that, the, of, to, than"
13800,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.131578947,"was, to, that, of, the"
13801,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.131578947,"a, in, that, sars-cov-2, or"
13802,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.131578947,"are, in, to, is, of, the, covid-19, virus, was, transmitted"
13803,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.131578947,"evidence, from, that, covid-19, to"
13804,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.131578947,"indicating, that, the, from, this"
13805,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.131578947,"the, were, huanan, and, that"
13806,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.131578947,"the, that, this, also, virus"
13807,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.131578947,"and, that, the, virus, is"
13808,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.131578947,"also, that, the, and, is"
13809,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.131578947,"that, to, infection, and, of"
13810,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.131578947,"a, of, to, that, and"
13811,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.131578947,"have, that, a, of, and"
13812,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.131578947,"the, of, sars-cov,, and, horseshoe"
13813,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.131578947,"is, to, and, coronavirus, from"
13814,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.131578947,"that, to, genome, bat, the"
13815,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.131578947,"and, the, was, to, a"
13816,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.131578947,"the, that, covid-19, to, and"
13817,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.131578947,"the, of, in, with, a"
13818,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.131578947,"the, indicate, that, in, to"
13819,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.131578947,"this, that, the, of, than"
13820,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.131578947,"the, of, sars-cov,, horseshoe, and"
13821,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.131578947,"coronavirus, is, and, from, to"
13822,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.131578947,"virus, from, to, the, is"
13823,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.131578947,"the, of, is, to, from"
13824,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.131578947,"the, sars-cov-2, is, and, to"
13825,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.131578947,"is, the, and, recombinant, sars-cov-2"
13826,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.131578947,"for, the, of, and, that, virus, from, a, with, to"
13827,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.131578947,"the, to, sars-cov-2, from, a"
13828,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.131578947,"coronavirus, to, similarity, sars-cov-2, the"
13829,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.131578947,"to, the, with, from, sars-cov-2"
13830,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.131578947,"from, with, to, the, of"
13831,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.131578947,"that, a, of, sars-cov-2, by"
13832,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.131578947,"sars-cov-2, of, has, to, a, virus, available, that, and, the"
13833,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.131578947,"a, that, the, virus, by"
13834,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.131578947,"of, a, virus, the, by"
13835,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.131578947,"a, that, of, to, and"
13836,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.131578947,"and, the, virus, to, a"
13837,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.131578947,"the, analysis, that, to, and"
13838,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.131578947,"the, bat, of, between, and"
13839,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.131578947,"the, of, is, to, pangolin"
13840,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.131578947,"the, market, are, to, and"
13841,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.131578947,"a, and, the, market, in"
13842,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.131578947,"the, to, and, was, a"
13843,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.131578947,"a, to, the, and, virus"
13844,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.131578947,"a, in, and, to, the"
13845,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.131578947,"was, to, the, its, in"
13846,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.131578947,"in, the, from, and, a"
13847,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.131578947,"bats, are, the, a, and"
13848,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.131578947,"in, of, to, the, are, virus, covid-19, was, transmitted, is"
13849,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.131578947,"the, of, virus, as, is"
13850,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.131578947,"that, the, at, of, virus"
13851,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.131578947,"the, animals, that, to, and"
13852,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.131578947,"in, that, the, more, to"
13853,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.131578947,"in, natural, and, to, the"
13854,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.131578947,"the, that, more, likely, virus"
13855,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.131578947,"in, is, that, the, and"
13856,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.131578947,"in, the, origin, virus, and"
13857,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.131578947,"seafood, and, wholesale, in, wuhan,"
13858,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.131578947,"the, bats, to, of, and"
13859,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.131578947,"the, of, virus, to, is"
13860,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.131578947,"that, the, of, and, bats"
13861,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.131578947,"bats, to, be, the, reservoir"
13862,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.131578947,"the, that, in, virus, was"
13863,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.131578947,"that, not, it, first, in"
13864,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.131578947,"however,, the, that, was, not"
13865,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.131578947,"the, of, bat, to, human"
13866,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.131578947,"of, the, genome, bat, coronavirus"
13867,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.131578947,"the, to, of, has, been"
13868,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.131578947,"the, genome, to, be, bat"
13869,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.131578947,"the, has, been, from, of"
13870,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.131578947,"sars-cov-2, virus, that, is, bat"
13871,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.131578947,"the, as, a, of, from"
13872,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.131578947,"a, of, viruses, in, the"
13873,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.131578947,"its, in, the, which, virus"
13874,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.131578947,"the, virus, in, causes, covid-19"
13875,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.131578947,"that, a, virus, animal, called"
13876,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.131578947,"the, virus, is, to, from"
13877,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.131578947,"the, is, a, spillover, to"
13878,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.131578947,"sars-cov-2, closely, related, from, bats"
13879,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.131578947,"closely, related, to, coronaviruses, in"
13880,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.131578947,"is, the, to, in, from"
13881,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.131578947,"the, is, to, of, from"
13882,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.131578947,"to, is, from, bats, the"
13883,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.131578947,"the, of, coronaviruses, from, in"
13884,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.131578947,"and, in, an, animal, or"
13885,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.131578947,"that, sars-cov-2, and, suggests, has"
13886,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.131578947,"t, that, and, the, species"
13887,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.131578947,"the, is, that, and, from"
13888,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.131578947,"the, that, sars-cov-2, is, animal"
13889,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.131578947,"indicated, that, the, to, and"
13890,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.131578947,"that, the, of, and, coronavirus"
13891,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.131578947,"to, from, with, the, of"
13892,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.131578947,"to, bats, be, the, reservoir"
13893,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.131578947,"the, bats, to, reservoir, of"
13894,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.131578947,"viruses, are, to, that, the"
13895,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.131578947,"that, the, to, includes, and"
13896,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.131578947,"that, are, to, and, the"
13897,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.131578947,"bats, a, coronavirus, as, the, of, and, be, with, to"
13898,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.131578947,"to, that, the, of, sars-cov-2"
13899,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.131578947,"that, the, beta, to, sars-cov-2"
13900,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.131578947,"of, analysis, that, the, to"
13901,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.131578947,"results, of, the, that, sars-cov-2"
13902,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.131578947,"that, bat, virus, has, of"
13903,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.131578947,"a, natural, on, comparative, analysis"
13904,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.131578947,"the, that, and, is, bat"
13905,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.131578947,"indicated, that, the, and, to"
13906,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.131578947,"a, in, that, was, at"
13907,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.131578947,"the, of, are, to, that"
13908,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.131578947,"sars-cov-2, virus, is, that, bat"
13909,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.131578947,"this, in, that, sars-cov-2, virus"
13910,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.131578947,"that, a, virus, in, this"
13911,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.131578947,"that, sars-cov-2, with, genome, the"
13912,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.131578947,"to, indicate, a, of, sequences, in, the, and, that, coronaviruses"
13913,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.131578947,"the, of, has, been, to"
13914,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.131578947,"of, the, to, that, was"
13915,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.131578947,"that, was, in, at, a"
13916,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.131578947,"of, a, that, the, to"
13917,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.131578947,"the, coronavirus, to, in, of"
13918,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.131578947,"that, the, of, may, host"
13919,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.131578947,"the, is, of, sars-cov-2, a"
13920,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.131578947,"the, of, that, sars-cov-2, a"
13921,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.131578947,"to, the, of, sars-cov-2, lineage"
13922,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.131578947,"of, the, to, and, was"
13923,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.131578947,"the, et, al.,, of, sars-cov-2"
13924,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.131578947,"the, was, to, and, sars-cov-2"
13925,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.131578947,"the, of, to, sars-cov-2, was"
13926,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.131578947,"viruses, of, the, been, in"
13927,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.131578947,"and, from, the, ratg13, of"
13928,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.131578947,"the, of, from, and, sars-cov-2"
13929,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.131578947,"the, of, natural, sars-cov-2, a"
13930,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.131578947,"natural, the, of, origin, and"
13931,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.131578947,"the, of, sars-cov-2, a, ratg13"
13932,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.131578947,"the, virus, which, its, in"
13933,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.131578947,"sars-cov-2, was, that, to, ratg13"
13934,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.131578947,"the, a, laboratory, was, to"
13935,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.131578947,"has, been, and, the, of"
13936,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.131578947,"the, of, zoonotic, a, in"
13937,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.131578947,"the, and, of, a, zoonotic"
13938,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.131578947,"a, zoonotic, and, in, the"
13939,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.131578947,"has, been, bat, and, a"
13940,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.131578947,"the, for, of, sars-cov-2, zoonotic"
13941,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.131578947,"viruses, in, to, the, reservoirs"
13942,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.131578947,"the, sars-cov-2, in, and, reservoirs"
13943,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.131578947,"of, to, the, and, for"
13944,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.131578947,"the, genetic, in, intermediate, host"
13945,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.131578947,"it, possible, a, sars-cov-2, the"
13946,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.131578947,"the, in, sars-cov-2, a, with"
13947,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.131578947,"is, that, sars-cov-2, to, or"
13948,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.131578947,"the, genome, sars-cov-2, and, to"
13949,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.131578947,"to, the, in, indicate, that"
13950,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.131578947,"in, is, that, the, sars-cov-2"
13951,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.131578947,"the, of, in, coronaviruses, from"
13952,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.131578947,"sars-cov-2, were, and, in, the"
13953,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.131578947,"in, of, that, has, a"
13954,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.131578947,"that, virus, has, of, bat"
13955,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.131578947,"that, sars-cov-2, a, bat, in"
13956,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.131578947,"the, that, a, of, origin"
13957,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.131578947,"is, a, origin, of, the"
13958,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.131578947,"is, the, that, sequence, and"
13959,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.131578947,"sequence, that, shows, the, sars-cov-2"
13960,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.131578947,"(2020), the, of, sars-cov-2, has"
13961,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.131578947,"the, two, and, show, with"
13962,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.131578947,"sars-cov-2, et, al.,, the, of"
13963,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.131578947,"the, of, amino, acid, sars-cov-2"
13964,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.131578947,"the, that, sars-cov-2, to, beta"
13965,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.131578947,"rbd, sars-cov-2, to, ace2, the"
13966,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.131578947,"it, is, sars-cov-2, through, of"
13967,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.131578947,"the, of, a, was, and"
13968,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.131578947,"additional, that, the, a, laboratory"
13969,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.131578947,"in, the, of, market, wuhan."
13970,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.131578947,"the, and, were, in, sars-cov-2"
13971,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.131578947,"the, at, sars-cov-2, in, animal"
13972,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.131578947,"intermediate, host, genetic, the, in"
13973,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.131578947,"similarity, sars-cov-2, bat, to, in"
13974,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.131578947,"presence, of, the, market, from"
13975,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.131578947,"the, sars-cov-2, market, that, in"
13976,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.131578947,"of, samples, from, in, sars-cov-2"
13977,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.131578947,"the, of, and, coronaviruses, indicate, that, sequences, a, in, to"
13978,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.131578947,"the, sars-cov-2, is, in, of"
13979,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.131578947,"the, natural, of, sars-cov-2, a"
13980,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.131578947,"the, of, a, zoonotic, in"
13981,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.131578947,"one, or, species, of, the"
13982,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.131578947,"including, coronaviruses, the, to, and"
13983,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.131578947,"the, in, of, an, to"
13984,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.131578947,"the, bat, to, in, of"
13985,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.131578947,"coronavirus, the, to, similarity, sars-cov-2"
13986,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.131578947,"the, of, viruses, to, sars-cov-2"
13987,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.131578947,"the, sars-cov-2, of, similarity, to"
13988,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.131578947,"that, the, of, is, to"
13989,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.131578947,"and, that, the, to, of"
13990,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.131578947,"the, are, to, that, of"
13991,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.131578947,"the, to, that, are, and"
13992,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.131578947,"the, that, of, and, to"
13993,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.131578947,"than, of, the, to, that"
13994,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.131578947,"the, of, rbd, to, that"
13995,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.131578947,"that, to, the, of, sars-cov-2."
13996,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.131578947,"the, to, rbd, of, than"
13997,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","This suggests that the BANAL series may be able to directly infect  

humans.",0.131578947,"to, the, suggests, that, may"
13998,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.131578947,"and, the, of, cleavage, site"
13999,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.131578947,"is, the, virus, as, of"
14000,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.131578947,"is, the, virus, of, to"
14001,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.131578947,"sars-cov-2, closely, related, to, in"
14002,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.131578947,"the, known, covid-19, is, to"
14003,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.131578947,"the, sars-cov-2, is, virus, in"
14004,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.131578947,"is, the, of, similar, covid-19"
14005,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.131578947,"the, is, and, that, in"
14006,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.131578947,"the, virus, for, a, of, to, with, that, from, and"
14007,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.131578947,"the, of, to, human, likely, a, or, that, this, evidence"
14008,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.131578947,"that, a, of, virus, with, to, and, the, intermediate, for"
14009,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.131578947,"the, of, a, zoonotic, and"
14010,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.131578947,"is, the, to, known, covid-19"
14011,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.131578947,"and, to, the, zoonotic, of"
14012,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.131578947,"evidence, between, and, the, of"
14013,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.131578947,"and, the, to, a, in"
14014,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.131578947,"the, natural, to, in, and"
14015,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.131578947,"of, the, in, viruses, a"
14016,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.131578947,"their, the, of, new, a"
14017,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.131578947,"an, animal, in, or, and"
14018,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.131578947,"sars-cov-2, a, in, an, host"
14019,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.131578947,"the, sequence, shows, that, sars-cov-2"
14020,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.131578947,"that, the, sars-cov-2, a, bat"
14021,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.131578947,"the, of, that, a, human, this, evidence, likely, or, to"
14022,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.131578947,"of, sars-cov-2, through, it, is"
14023,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.131578947,"the, virus, is, that, from"
14024,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.131578947,"is, virus, that, from, the"
14025,"This suggests that the BANAL series may be able to directly infect  

humans.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.131578947,"suggests, that, the, may, to"
14026,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.131578947,"the, cleavage, site, of, and"
14027,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.131578947,"a, possible, sars-cov-2, it, the"
14028,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.131578947,"r., that, of, sars-cov-2, the"
14029,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.131578947,"that, the, also, this, virus"
14030,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.131578947,"to, an, in, the, of"
14031,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.131578947,"the, and, a, one, that"
14032,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.131578947,"a, analysis, of, that, the"
14033,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.131578947,"a, of, their, the, new"
14034,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.131578947,"the, genome, analysis, that, covid-19"
14035,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.131578947,"the, virus, causes, covid-19, in"
14036,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.131578947,"virus, that, animal, a, called"
14037,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.131578947,"a, virus, that, in, this"
14038,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.131578947,"the, of, sequence, identity, sars-cov"
14039,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.131578947,"evidence, to, the, that, from"
14040,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.131578947,"that, evidence, covid-19, from, to"
14041,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.131578947,"the, covid-19, to, and, that"
14042,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.131578947,"analysis, to, that, the, and"
14043,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.131578947,"to, bats,, which, the, animals"
14044,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",The COVID-19 most likely developed from bat origin coronaviruses,0.131578947,"the, covid-19, bat, origin, from"
14045,The COVID-19 most likely developed from bat origin coronaviruses,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.131578947,"the, covid-19, from, bat, origin"
14046,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.131578947,"of, the, in, that, market,"
14047,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.131578947,"the, of, and, unknown, intermediate"
14048,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.131578947,"to, humans, through, in, be"
14049,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.131578947,"be, in, that, originated, bats."
14050,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.131578947,"the, was, in, that, of"
14051,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.131578947,"that, the, in, market,, of"
14052,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.131578947,"the, and, sars-like, similar, to"
14053,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.131578947,"to, the, for, and, of"
14054,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.131578947,"the, one, or, species, of"
14055,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.131578947,"the, of, that, or, is"
14056,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.131578947,"between, bats, and, the, from"
14057,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.131578947,"the, host, and, an, intermediate"
14058,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.131578947,"the, was, in, of, a"
14059,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.131578947,"of, the, in, market, wuhan."
14060,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.131578947,"between, and, the, in, wildlife"
14061,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.131578947,"the, of, in, viruses, been"
14062,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.131578947,"the, in, from, markets, china"
14063,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.131578947,"from, bats, between, and, the"
14064,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.131578947,"in, the, between, and, wildlife"
14065,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.131578947,"the, and, that, a, of"
14066,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.131578947,"that, the, covid-19, and, of"
14067,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.131578947,"that, the, of, and, this"
14068,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.131578947,"a, and, has, been, bat"
14069,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.131578947,"the, virus, is, that, of"
14070,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.131578947,"the, virus, to, of, and"
14071,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.131578947,"the, of, zoonotic, to, virus"
14072,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.131578947,"the, and, of, zoonotic, to"
14073,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.131578947,"on, comparative, analysis, natural, a"
14074,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.131578947,"with, the, encounters, wildlife, field"
14075,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.131578947,"that, in, it, not, first"
14076,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.131578947,"that, a, bat, in, sars-cov-2"
14077,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.131578947,"is, that, to, sars-cov-2, or"
14078,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.131578947,"is, that, or, of, the"
14079,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.131578947,"encounters, the, field, with, wildlife"
14080,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.131578947,"that, the, is, laboratory, or"
14081,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.131578947,"that, the, of, sars-cov-2, a"
14082,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.131578947,"the, of, that, has, a"
14083,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.131578947,"the, that, sars-cov-2, has, of"
14084,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.131578947,"the, of, that, sars-cov-2, not"
14085,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.131578947,"the, genome, to, bat, be"
14086,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.131578947,"virus, and, natural, of, origin"
14087,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.131578947,"was, that, sars-cov-2, and, to"
14088,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.131578947,"sars-cov-2, and, identical, to, that"
14089,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.131578947,"that, sars-cov-2, was, to, ratg13"
14090,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.131578947,"the, from, conclusive, evidence, be"
14091,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.131578947,"to, with, the, of, sars-cov-2"
14092,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.131578947,"of, sars-cov-2, relatives, and, tion"
14093,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.131578947,"of, bat, from, relatives, sars-cov-2"
14094,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.131578947,"its, the, was, to, in"
14095,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.131578947,"the, rbd, to, sars-cov-2, ace2"
14096,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.131578947,"the, to, which, bats,, animals"
14097,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.131578947,"the, natural, origin, of, and"
14098,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.131578947,"the, that, bats, hosts, for"
14099,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.131578947,"the, more, likely, that, virus"
14100,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.131578947,"analysis, that, the, genome, covid-19"
14101,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.131578947,"that, bats, the, hosts, for"
14102,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.131578947,"the, that, as, a, bats"
14103,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.131578947,"a, is, the, to, that"
14104,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.131578947,"a, that, the, sars-cov-2, bat"
14105,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.131578947,"the, to, that, sars-cov-2, bats"
14106,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.131578947,"of, the, analysis, that, to"
14107,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.131578947,"for, the, of, and, intermediate, that, virus, a, with, to"
14108,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.131578947,"two, the, and, show, with"
14109,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.131578947,"sars-cov-2, of, coronavirus, and, the"
14110,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.131578947,"suggests, that, sars-cov-2, has, and"
14111,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.131578947,"that, the, of, coronavirus, and"
14112,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.131578947,"(2020), has, the, of, sars-cov-2"
14113,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.131578947,"in, bat, to, and, sars-cov-2."
14114,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.131578947,"bat, similarity, to, sars-cov-2, in"
14115,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.131578947,"the, sars-cov-2, is, in, bat"
14116,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.131578947,"is, the, to, sars-cov-2, in"
14117,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.131578947,"this, of, the, than, that"
14118,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.131578947,"that, the, and, also, is"
14119,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.131578947,"and, to, that, the, of, sars-, bats, are, hosts, sars-cov-2"
14120,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.131578947,"the, of, between, bat, and"
14121,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.131578947,"the, virus, and, origin, in"
14122,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.131578947,"on, genome, and, of, origin"
14123,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.131578947,"the, that, sars-cov-2, of, bat"
14124,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.131578947,"to, sars-cov-2, is, and, the"
14125,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.131578947,"the, of, and, with, sars-cov-2"
14126,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.131578947,"the, is, of, sars-cov-2, to"
14127,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.131578947,"the, and, is, of, to"
14128,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.131578947,"to, the, of, and, is"
14129,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.131578947,"sars-cov-2, is, to, the, with"
14130,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.131578947,"the, of, sars-cov-2, to, with"
14131,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.131578947,"the, and, of, that, emergence"
14132,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.131578947,"the, of, and, in, sars-cov-2"
14133,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.131578947,"the, between, and, of, evidence"
14134,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.131578947,"and, the, from, a, in"
14135,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.131578947,"the, reservoir, that, and, mers-cov"
14136,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.131578947,"have, a, that, of, and"
14137,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.131578947,"are, and, the, bats, a"
14138,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.131578947,"sars-cov-2, is, recombinant, and, the"
14139,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.131578947,"the, that, in, virus, and"
14140,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.131578947,"and, that, the, virus, of"
14141,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.131578947,"the, that, of, virus, and"
14142,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.131578947,"sars-cov-2, at, the, of, with"
14143,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.131578947,"of, sars-cov-2, has, that, the"
14144,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.131578947,"that, the, however,, was, not"
14145,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.131578947,"the, of, to, rbd, that"
14146,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.131578947,"of, sars-cov-2, not, that, the"
14147,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.131578947,"that, bats, the, sars-cov-2, to"
14148,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.131578947,"the, pangolin, is, to, of"
14149,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.131578947,"to, a, of, the, transmission"
14150,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.131578947,"the, virus, zoonotic, of, to"
14151,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.131578947,"the, that, animal, in, origin"
14152,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.131578947,"be, that, sars-cov-2, originated, from"
14153,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.131578947,"the, and, unknown, intermediate, of"
14154,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.131578947,"an, intermediate, host, and, the"
14155,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.131578947,"is, that, sars-cov-2, the, animal"
14156,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.131578947,"animal, sars-cov-2, in, at, the"
14157,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.131578947,"is, the, virus, sars-cov-2, in"
14158,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.131578947,"that, sars-cov-2, or, a, in"
14159,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.131578947,"that, be, originated, in, bats."
14160,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.131578947,"that, sars-cov-2, be, originated, from"
14161,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.131578947,"samples, from, of, in, sars-cov-2"
14162,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.131578947,"of, sars-cov-2, from, bat, relatives"
14163,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.131578947,"the, of, in, that, was"
14164,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.131578947,"the, to, in, of, gene"
14165,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.131578947,"to, that, sars-, the, of, bats, and, hosts, are, sars-cov-2"
14166,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.131578947,"of, known, to, be, the"
14167,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.131578947,"coronavirus, in, the, to, of"
14168,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.131578947,"bat, to, in, the, of"
14169,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.131578947,"the, rbd, of, to, than"
14170,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.131578947,"in, to, of, the, gene"
14171,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.131578947,"that, the, may, host, of"
14172,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.131578947,"related, the, more, closely, to"
14173,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.131578947,"that, the, a, laboratory, additional"
14174,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.131578947,"the, that, or, laboratory, is"
14175,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.131386861,"evidence, that, palm, civets, were, infected, from, in, the, market, a, at, animals, and, of, animal, may, markets"
14176,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.131386861,"in, may, the, animals, animal, markets, of, from, that, palm, civets, at, market, were, infected, a, and, evidence"
14177,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.131313131,"an, bat, to, a, as, from, animal, in, china, identified, several, and, species"
14178,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.131313131,"the, was, also, for, to, a, that, used, ace2, entry, receptor, and, by"
14179,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.131313131,"and, they, can, also, come, into, contact, with, are, to, bats, a, cave"
14180,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.131313131,"a, was, that, the, also, ace2, receptor, and, for, entry, to, used, by"
14181,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.131313131,"from, an, animal, to, a, as, several, identified, and, in, bat, species, china"
14182,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.131313131,"and, also, to, are, a, bats, cave, they, with, come, into, contact, can"
14183,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.131147541,"of, virus, for, more, than, that, with, and"
14184,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.131147541,"the, of, coronaviruses, a, and, sars-cov-2, via, recombination"
14185,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.131147541,"to, a, in, the, can, use, ace2, for"
14186,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.131147541,"the, of, to, is, that, bats, as, for"
14187,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.131147541,"in, a, for, to, with, novel, coronavirus, that"
14188,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.131147541,"from, in, the, is, to, of, found, bats"
14189,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.131147541,"sars-cov-2, a, origin, and, in, before, zoonotic, humans"
14190,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.131147541,"the, and, that, of, to, huanan, through, market"
14191,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.131147541,"the, respiratory, syndrome, coronavirus, been, in, of, and"
14192,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.131147541,"sars-cov-2, and, in, do, not, that, any, is"
14193,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.131147541,"a, virus, from, to, for, the, first, is"
14194,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.131147541,"our, of, data, the, that, is, a, virus"
14195,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.131147541,"is, and, likely, that, of, sars-cov-2, to, an"
14196,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.131147541,"the, that, virus, samples, taken, from, were, and"
14197,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.131147541,"to, the, in, of, and, that, a, wuhan,"
14198,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.131147541,"that, a, the, covid-19, of, virus, genome, from"
14199,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.131147541,"and, a, of, about, which, the, for, to"
14200,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.131147541,"that, and, sars-cov-2, to, humans, based, on, the"
14201,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.131147541,"in, the, of, virus, is, to, has, and"
14202,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.131147541,"found, the, analysis, of, which, was, to, rbd"
14203,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.131147541,"that, the, similarity, of, sars-cov-2, and, et, al.,"
14204,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.131147541,"a, to, the, virus, first, is, from, for"
14205,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.131147541,"the, of, closely, related, is, in, to, sars"
14206,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.131147541,"that, likely, of, sars-cov-2, and, is, to, an"
14207,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.131147541,"december, a, wuhan, and, market, were, exposed, in"
14208,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.131147541,"of, sequences, to, a, genome, sequence, bat, in"
14209,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.131147541,"is, sars-cov-2, and, bat, to, between, that, in"
14210,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.131147541,"the, similarity, sars-cov-2, and, of, et, al.,, that"
14211,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.131147541,"in, the, of, was, a, at, that, to"
14212,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.131147541,"of, cases, had, to, reported, the, huanan, only"
14213,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.131147541,"of, from, to, an, a, in, sars-cov-2, the"
14214,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.131147541,"a, et, from, was, in, the, to, of"
14215,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.131147541,"analysis, the, was, found, to, which, rbd, of"
14216,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.131147541,"of, more, than, and, that, for, virus, with"
14217,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.131147541,"in, to, is, of, the, virus, has, and"
14218,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.131147541,"the, to, sars-cov-2, in, from, an, of, a"
14219,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.131147541,"with, the, of, worldwide, humans, that, an, is"
14220,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.131147541,"the, from, that, sars-cov-2, to, a, pangolin, coronavirus"
14221,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.131147541,"sars-cov-2, of, the, and, to, in, infection, ace2"
14222,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.131147541,"a, for, the, can, in, to, use, ace2"
14223,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.131147541,"based, on, the, and, that, sars-cov-2, to, humans"
14224,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.131147541,"that, sars-cov-2, has, the, with, of, and, to"
14225,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.131147541,"the, virus, covid-19, a, genome, of, that, from"
14226,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.131147541,"the, of, sars-cov-2, is, result, a, or, that"
14227,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.131147541,"of, that, the, covid-19, is, a, from, or"
14228,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.131147541,"in, for, sars, the, to, virus, closely, related"
14229,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.131147541,"and, to, that, the, of, sars-, is, are"
14230,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.131147541,"the, of, sars, in, is, closely, related, to"
14231,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.131147541,"samples, that, were, taken, from, the, and, virus"
14232,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.131147541,"a, in, the, that, was, to, of, at"
14233,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.131147541,"and, in, were, exposed, a, market, wuhan, december"
14234,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.131147541,"only, of, reported, cases, to, the, huanan, had"
14235,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.131147541,"through, the, huanan, market, that, to, and, of"
14236,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.131147541,"a, origin, sars-cov-2, and, zoonotic, in, before, humans"
14237,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.131147541,"is, that, sars-cov-2, a, the, result, of, or"
14238,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.131147541,"a, of, sars-cov-2, binding, is, the, to, human"
14239,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.131147541,"bats, for, as, the, of, is, that, to"
14240,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.131147541,"sars-cov-2, of, the, similar, to, in, virus, rbd"
14241,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.131147541,"the, sars-cov-2, and, a, of, coronaviruses, via, recombination"
14242,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.131147541,"that, do, not, sars-cov-2, and, is, any, in"
14243,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.131147541,"the, and, a, to, that, bat, not, but"
14244,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.131147541,"is, that, a, the, covid-19, of, or, from"
14245,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.131147541,"the, genomic, of, in, and, that, originated, through"
14246,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.131147541,"coronavirus, and, in, respiratory, syndrome, been, the, of"
14247,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.131147541,"that, the, of, in, wuhan,, to, a, and"
14248,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.131147541,"transmission, or, can, of, and, in, thousands, bats"
14249,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.131147541,"can, or, thousands, of, and, in, bats, transmission"
14250,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.131147541,"a, the, of, data, our, virus, that, is"
14251,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.131147541,"have, been, by, to, the, of, origin, has"
14252,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.131147541,"that, of, humans, an, is, with, worldwide, the"
14253,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.131147541,"of, the, has, been, by, have, to, origin"
14254,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.131147541,"evidence, to, the, of, and, have, origin, sars-cov-2"
14255,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.131147541,"that, from, to, a, coronavirus, pangolin, sars-cov-2, the"
14256,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.131147541,"the, to, from, bats, in, of, is, found"
14257,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.131147541,"the, to, was, in, from, of, a, et"
14258,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.131147541,"the, to, that, sars-cov-2, is, bat, are, as"
14259,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.131147541,"genome, of, bat, sequences, a, sequence, in, to"
14260,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.131147541,"the, for, a, of, about, which, to, and"
14261,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.131147541,"the, binding, of, sars-cov-2, to, human, is, a"
14262,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.131147541,"genomic, that, the, originated, in, and, through, of"
14263,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.131147541,"sars-cov-2, is, between, and, bat, to, that, in"
14264,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.131147541,"is, that, are, the, sars-cov-2, as, to, bat"
14265,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.131147541,"have, and, to, the, evidence, of, sars-cov-2, origin"
14266,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.131147541,"in, a, novel, coronavirus, that, to, with, for"
14267,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.131147541,"the, of, and, are, to, is, that, sars-"
14268,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.131147541,"the, to, bat, and, that, a, but, not"
14269,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.131147541,"in, ace2, of, to, sars-cov-2, and, the, infection"
14270,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.131147541,"the, in, of, rbd, similar, to, sars-cov-2, virus"
14271,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.131034483,"the, live, from, including, and, were, in, all, by, however,, of, had, a, as, to, infected, at, one, virus"
14272,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.131034483,"at, infected, had, to, a, however,, as, from, in, the, virus, by, all, live, were, one, of, and, including"
14273,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.130952381,"and, bat, to, viruses, are, a, closely, related, other, in, which"
14274,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.130952381,"and, in, to, be, that, the, of, coronavirus, is, bats, are"
14275,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.130952381,"and, are, closely, related, to, bat, in, a, which, other, viruses"
14276,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.130952381,"the, huanan, market, wuhan, of, to, by, and, with, who, a"
14277,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.130952381,"the, by, a, who, huanan, market, and, to, of, wuhan, with"
14278,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.130952381,"bats, are, coronavirus, the, of, is, and, be, in, that, to"
14279,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.130841121,"the, are, to, in, a, for, of, as, with, is, that, bats, virus, and"
14280,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.130841121,"to, as, several, and, a, reservoir, in, species, from, high, coronaviruses, have, an, found"
14281,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.130841121,"the, of, closely, related, is, for, in, a, virus, similar, to, sars-related, cave, that"
14282,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.130841121,"the, of, to, similar, sars-related, a, closely, related, cave, that, in, for, virus, is"
14283,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.130841121,"have, from, an, reservoir, to, a, as, several, high, and, coronaviruses, found, in, species"
14284,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.130841121,"of, had, a, exposure, to, markets., having, other, markets, and, the, were, in, earliest"
14285,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.130841121,"bats, are, a, for, as, the, of, is, virus, and, in, with, that, to"
14286,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.130841121,"had, to, a, in, the, markets, earliest, having, exposure, were, of, markets., and, other"
14287,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.130769231,"the, market, is, only, that, in, for, of, were, to, by, chinese, and, public, health, a, known"
14288,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.130769231,"in, the, known, public, health, of, that, for, only, chinese, market, to, were, by, a, is, and"
14289,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.130434783,"of, data, the, that, a, naturally"
14290,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.130434783,"sars-cov-2, to, a, closely, related, in"
14291,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.130434783,"sars-cov-2, are, to, a, bat, pangolin"
14292,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.130434783,"of, the, pandemic, from, this, and, viruses, into, humans"
14293,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.130434783,"the, virus, into, human, from, and"
14294,Many of these CoVs can infect several animal species as well,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.130434783,"of, animal, species"
14295,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.130434783,"an, reservoir, of"
14296,Bats are hosts of many coronaviruses,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.130434783,"bats, of, many"
14297,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.130434783,"is, to, in"
14298,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.130434783,"is, a, coronavirus"
14299,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.130434783,"the, in, bats"
14300,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.130434783,"bats, in, the"
14301,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.130434783,"the, are, in"
14302,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.130434783,"the, virus, and, may, of, to"
14303,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.130434783,"the, of, sars-cov-2, is, with, to"
14304,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.130434783,"origin, of, be, that, have, sars-cov-2"
14305,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.130434783,"sars-cov-2, from, to, genetically, coronaviruses, the"
14306,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.130434783,"of, the, that, sars-cov-2, to, coronaviruses"
14307,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.130434783,"a, naturally, occurring, the, of, sars-cov-2, and, is, to"
14308,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.130434783,"and, be, sars-cov-2, to, other, the, between, amino, in"
14309,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.130434783,"the, sars-cov-2, found, to, be, bat"
14310,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.130434783,"t, is, that, sars-cov-2, the, from"
14311,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.130434783,"these, and, that, the, bat, of"
14312,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.130434783,"to, that, emergence, the, of, and"
14313,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.130434783,"the, of, that, are, to, bat"
14314,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.130434783,"the, of, sars-cov-2, to, it, is"
14315,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.130434783,"bat, cov, is, the, sars-cov-2, that"
14316,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.130434783,"that, sars-cov-2, and, throughout, the, genome"
14317,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.130434783,"to, and, of, is, in, bat"
14318,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",Originating from reservoir of bat,0.130434783,"of, from, bat"
14319,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.130434783,"be, that, origin, of, sars-cov-2, have"
14320,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.130434783,"the, sars-cov-2, animal, that, and, reservoirs"
14321,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.130434783,"the, origin, to, that, and, humans"
14322,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.130434783,"have, of, bats, the, known, as"
14323,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.130434783,"can, as, that, virus, to, for, and, the, into"
14324,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.130434783,"in, a, of, for, to, be, with, coronavirus, that"
14325,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.130434783,"the, as, intermediate"
14326,Wet Market animals maintained in poor conditions,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.130434783,"wet, market, in"
14327,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.130434783,"a, and, were, linked, to, in"
14328,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.130434783,"the, a, of, to, coronavirus, and"
14329,"the close relation  

between SARS coronavirus and 2019-nCoV","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.130434783,"the, coronavirus, and"
14330,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.130434783,"the, of, sars-cov-2, to, is, a"
14331,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.130434783,"a, of, to, and, the, sars-cov-2"
14332,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.130434783,"bats, the, be, of, cov,, and"
14333,"This suggests that the BANAL series may be able to directly infect  

humans.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.130434783,"the, may, be"
14334,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.130434783,"the, of, sars-"
14335,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.130434783,"and, the, bats, natural, reservoirs, of"
14336,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.130434783,"bats, are, the, natural, of, and"
14337,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.130434783,"for, as, the, virus, can, and, that, to, into"
14338,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.130434783,"that, the, hosts, for, as, to"
14339,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.130434783,"that, natural, and, the, virus, for"
14340,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.130434783,"the, which, is, to, identical, from"
14341,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",zoonotic origins of SARS-CoV-2 by natural evolution,0.130434783,"of, sars-cov-2, by"
14342,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.130434783,"the, a, to, with, coronavirus, from"
14343,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.130434783,"the, of, to, and, which, species"
14344,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.130434783,"in, the, of, is, that, sars-cov-2"
14345,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.130434783,"whole, genome, of, the, with, and"
14346,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.130434783,"sars-cov-2, the, and, that, of, is"
14347,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.130434783,"the, that, are, of, natural, for"
14348,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.130434783,"that, the, of, bats, for, are"
14349,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","civet cats and raccoon dogs  

are the intermediate hosts",0.130434783,"and, intermediate, hosts"
14350,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.130434783,"sars-cov-2, transmitted, animal, to, are, and"
14351,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.130434783,"sars-cov-2, is, to, bats, be, the"
14352,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.130434783,"a, it, was, that, the, by"
14353,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.130434783,"animal, sars-cov-2, are, and, transmitted, to"
14354,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.130434783,"been, coronaviruses, are, from, bat, reservoir"
14355,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.130434783,"from, to, an, host, a, found, in, sars-cov-2, species"
14356,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.130434783,"the, of, that, sars-cov-2, to, humans"
14357,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.130434783,"that, the, to, humans, from, a"
14358,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.130434783,"the, of, as, a, natural, from"
14359,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.130434783,"genome, the, throughout, and, that, sars-cov-2"
14360,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.130434783,"the, and, of, bat, that, these"
14361,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.130434783,"the, that, of, and, coronavirus, from"
14362,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.130434783,"of, the, and, was, bat, coronavirus"
14363,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.130434783,"sars-cov-2, was, that"
14364,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.130434783,"sars-cov-2, likely, from"
14365,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.130434783,"this, of, closer, to, the, that"
14366,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.130434783,"two, viruses, to, a, at, the"
14367,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.130434783,"pandemic, and, viruses, from, of, this, the, into, humans"
14368,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.130434783,"the, of, and, that, sars-cov-2, to"
14369,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.130434783,"the, huanan, market, and, to, of"
14370,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.130434783,"of, the, early, cases, in, that"
14371,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.130434783,"that, the, in, to, a, market"
14372,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.130434783,"the, in, and, at, a, market"
14373,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.130434783,"and, this, with, the, in, of"
14374,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.130434783,"this, of, and, a, in, the"
14375,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.130434783,"in, is, at, with, the, of"
14376,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.130434783,"the, with, in, this, consistent, of, origin, and, subsequent"
14377,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.130434783,"the, that, and, animal, reservoirs, sars-cov-2"
14378,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.130434783,"of, cases, to, the, than, that"
14379,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor",0.130434783,"sars-cov-2, a, to"
14380,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.130434783,"that, sars-cov-2, is, not, laboratory, virus."
14381,"expended to make the simple point 

that COVID-19 had a natural origin.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.130434783,"that, had, a"
14382,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.130434783,"to, a, that, from, the, as"
14383,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.130434783,"the, that, to, a, mutations, it"
14384,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.130434783,"the, that, from, a, in, evidence, humans, as, to"
14385,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.130434783,"the, market, evidence, a, spillover, to"
14386,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.130434783,"the, of, is, for, likely, in, found, a, virus, to, that, same"
14387,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.130434783,"the, of, this, that, is, a, virus, in, for"
14388,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.130434783,"there, is, that, to, an, animal"
14389,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.130434783,"the, sars-cov-2, and, to, a, of, is, naturally, occurring"
14390,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.130434783,"the, was, to, that, has, with"
14391,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.130434783,"to, that, has, similarity, the, virus"
14392,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.130434783,"have, in, from, their, origin, and"
14393,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.130434783,"studies, the, and, that, was, to"
14394,"Bats are natural hosts of many of the known  

coronaviruses","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.130434783,"of, the, known"
14395,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.130434783,"huanan, in, wuhan,, the, and, of"
14396,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.130434783,"that, and, in, were, a, market"
14397,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.130434783,"of, cases, to, the, huanan, that"
14398,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.130434783,"in, of, were, to, and, the"
14399,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.130434783,"and, near, the, of, that, a"
14400,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.130434783,"closer, to, that, the, of, this"
14401,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.130434783,"than, of, the, cases, to, that"
14402,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.130434783,"of, cases, to, the, that, had"
14403,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.130434783,"of, that, the, virus, to, which"
14404,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.130434783,"is, identical, the, to, which, from"
14405,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.130434783,"the, of, that, is, virus, has"
14406,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.130434783,"the, that, a, as, to, from"
14407,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.130434783,"the, is, sars-cov-2, to, a, virus"
14408,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.130434783,"to, that, the, and, is, be"
14409,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.130434783,"sars-cov-2, is, to, originated, the, pangolin"
14410,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.130434783,"the, that, sars-cov-2, to, a, pangolin"
14411,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.130434783,"to, a, of, coronavirus, and, the"
14412,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.130434783,"to, the, with, a, coronavirus, from"
14413,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.130434783,"to, from, a, of, the, and, has, that, with"
14414,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.130434783,"a, that, the, covid-19, of, and"
14415,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Bats have been reported as being the rich source of 

coronaviruses",0.130434783,"of, the, bats"
14416,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.130434783,"the, pangolin, sars-cov-2"
14417,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.130434783,"sars-cov-2, from, bat"
14418,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.130434783,"with, sars-cov-2, the"
14419,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.130434783,"sars-cov-2, from, ratg13"
14420,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.130434783,"and, that, of, sars-cov-2, to, by"
14421,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.130434783,"the, by, a, and, to, of"
14422,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.130434783,"the, of, bat, is, and, human"
14423,"According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.130434783,"to, the, of"
14424,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.130434783,"between, and, pangolin"
14425,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.130434783,"to, the, that, sars-cov-2, of, humans"
14426,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.130434783,"studies, the, to, and, that, was"
14427,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.130434783,"its, in, the, was, to, virus"
14428,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.130434783,"from, a, to, its, in, the"
14429,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.130434783,"a, and, at, the, market, in"
14430,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.130434783,"have, that, bats, the, a, and"
14431,". In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.130434783,"., in, the, of, was, and"
14432,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.130434783,"the, covid-19, is, of, and, animals"
14433,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.130434783,"in, has, been"
14434,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.130434783,"that, to, in"
14435,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.130434783,"the, of, is, a, that, evidence"
14436,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.130434783,"the, origin, to, that, humans, and"
14437,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.130434783,"the, of, in, wuhan,, and, huanan"
14438,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.130434783,"to, the, of, and, may, virus"
14439,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.130434783,"the, is, of, bat, and, human"
14440,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.130434783,"the, reservoir, of"
14441,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.130434783,"the, sars-cov-2, to, bats, is, be"
14442,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.130434783,"related, bat, to, is, sars-cov-2, the"
14443,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.130434783,"results, that, samples, from, the, for"
14444,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.130434783,"of, the, novel, coronavirus, with, bat"
14445,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.130434783,"a, coronavirus, the, with, that, of"
14446,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.130434783,"the, to, of"
14447,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.130434783,"a, that, the, was, it, by"
14448,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.130434783,"the, that, host, is, by, a"
14449,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.130434783,"bats, be, the, of, cov,, and"
14450,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.130434783,"with, beta, the, of, another, as, and, analysis, sars-cov"
14451,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.130434783,"recombination, analysis, the, for, transmission, and"
14452,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.130434783,"analysis, as, the, sars-cov, with, of, another, beta, and"
14453,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.130434783,"been, from, reservoir, are, coronaviruses, bat"
14454,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.130434783,"that, the, of, new, genome, bat"
14455,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.130434783,"the, bats, in"
14456,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.130434783,"from, that, to"
14457,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.130434783,"it, is, a, the, virus, from"
14458,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.130434783,"sars-cov-2, the, to, coronaviruses, from, genetically"
14459,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.130434783,"the, in, bats, from, is, to"
14460,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.130434783,"closely, related, coronaviruses, to, in, the"
14461,The COVID-19 most likely developed from bat origin coronaviruses,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.130434783,"the, from, coronaviruses"
14462,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.130434783,"also, of, in, is, the, to"
14463,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.130434783,"human, and, from, the, virus, into"
14464,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.130434783,"the, have, been, in, from, and"
14465,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.130434783,"in, the, from, animal, human, or"
14466,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.130434783,"t, is, that, sars-cov-2, from, the"
14467,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.130434783,"that, there, is, an, animal, to"
14468,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.130434783,"of, to, that, sars-cov-2, by, and"
14469,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.130434783,"that, of, virus, to, and, the"
14470,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.130434783,"and, the, bat, coronavirus, was, of"
14471,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.130434783,"the, of, and, identity, with, genome"
14472,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.130434783,"the, of, genomes, with, bat, genome"
14473,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.130434783,"this, with, and, of, the, in"
14474,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.130434783,"the, whole, genome, of, with, and"
14475,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.130434783,"the, of, covid-19, patients, with, in"
14476,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",COVID-19 is a zoonotic virus,0.130434783,"is, covid-19, a"
14477,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.130434783,"to, with, the, of, from, virus"
14478,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.130434783,"to, of, the, covid-19, virus, bats"
14479,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.130434783,"are, viruses, to, the, and, that"
14480,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.130434783,"bats, and, the, natural, reservoirs, of"
14481,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.130434783,"sars-cov-2, the, of, that, to, coronaviruses"
14482,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.130434783,"to, that, has, the, virus, of"
14483,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.130434783,"the, genome, and, that, a, not"
14484,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.130434783,"the, from, that, sars-cov-2, a, and"
14485,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.130434783,"at, only, bat, is, the, that"
14486,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.130434783,"the, from, that, to, a, and"
14487,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","the close relation  

between SARS coronavirus and 2019-nCoV",0.130434783,"coronavirus, and, the"
14488,"�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same","the close relation  

between SARS coronavirus and 2019-nCoV",0.130434783,"sars, and, the"
14489,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.130434783,"that, were, in, a, and, market"
14490,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.130434783,"china, a, in, and, market, were, at, was, isolated"
14491,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.130434783,"on, patients, in, wuhan, china, and"
14492,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.130434783,"the, of, with, in, province,, china"
14493,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.130434783,"from, bat, sars-cov-2"
14494,"This suggests that the BANAL series may be able to directly infect  

humans.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.130434783,"this, that, may"
14495,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.130434783,"sars-cov-2, from, that"
14496,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.130434783,"the, analysis, of, and, that, sars-cov-2"
14497,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.130434783,"the, are, of"
14498,"The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.130434783,"the, sources, and"
14499,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.130434783,"sars-cov-2, are, and"
14500,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.130434783,"the, samples, from, results, for, that"
14501,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.130434783,"the, for, which, from, wild, animals"
14502,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","Bats are natural hosts of many of the known  

coronaviruses",0.130434783,"the, of, natural"
14503,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Bats are natural hosts of many of the known  

coronaviruses",0.130434783,"the, of, known"
14504,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Bats are natural hosts of many of the known  

coronaviruses",0.130434783,"bats, are, natural, hosts, of, many"
14505,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.130434783,"has, been, that, and, the, of"
14506,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.130434783,"the, mutations, that, a, it, to"
14507,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.130434783,"the, is, of, to, a, virus"
14508,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.130434783,"the, and, is, of, a, to"
14509,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.130434783,"a, of, the, coronavirus, with, that"
14510,"expended to make the simple point 

that COVID-19 had a natural origin.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.130434783,"the, that, a"
14511,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.130434783,"that, of, the"
14512,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.130434783,"that, the, of"
14513,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.130434783,"the, with, sars-cov-2"
14514,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.130434783,"the, are, sars-cov-2"
14515,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.130434783,"that, the, of, cases, to, huanan"
14516,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.130434783,"a, of, data, that, the, naturally"
14517,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.130434783,"the, of, is, that, sars-cov-2, a"
14518,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.130434783,"is, that, sars-cov-2, a, the, of"
14519,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.130434783,"sars-cov-2, the, closest, of, genome,, to"
14520,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.130434783,"the, was, bat"
14521,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.130434783,"pangolin, between, and"
14522,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.130434783,"that, the, of, a, was, and"
14523,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.130434783,"has, been, in"
14524,The COVID-19 most likely developed from bat origin coronaviruses,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.130434783,"the, from, origin"
14525,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.130434783,"its, the, virus, was, to, in"
14526,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.130434783,"all, are, in"
14527,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.130434783,"the, species, which, to, of, and"
14528,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.130434783,"these, viruses, have, a, which, of"
14529,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.130434783,"that, were, related, to, found, bats"
14530,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.130434783,"the, as, a, of, from, natural"
14531,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.130434783,"bats, the, for, a, of, and"
14532,"Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.130434783,"to, a, sars-cov-2"
14533,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.130434783,"the, of, to, may, be, possible"
14534,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.130434783,"covid-19, the, that, sars-cov-2, pandemic, or"
14535,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.130434783,"to, sars-cov-2, in, the, that, is"
14536,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.130434783,"and, the, of, to, a, with, that, this, in, for, virus, is"
14537,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.130434783,"is, more, 2, in, the, of"
14538,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.130434783,"is, the, with, and, for, sars-cov-2"
14539,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.130434783,"sars-cov-2, from, an, host, to, a, found, in, species"
14540,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.130434783,"suggests, the, pangolin, intermediate, host, sars-cov-2"
14541,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.130434783,"of, the, genome, and, with, identity"
14542,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.130434783,"the, of, and, were, collected, from, nucleotide, in, with"
14543,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.130434783,"sars-cov-2, a, coronavirus"
14544,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.130434783,"is, that, sars-cov-2"
14545,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.130434783,"a, that, the, host, is, by"
14546,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.130434783,"in, the, bat-, and, pangolin-covs, an"
14547,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","bats are also important reservoir species for a great 

range of coronaviruses",0.130434783,"bats, for, of"
14548,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.130434783,"the, of, were, in, to, and"
14549,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.130434783,"the, rbd, of, sars-cov-2, at, which"
14550,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.130434783,"the, in, is, to, from, bats"
14551,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.130434783,"to, sars-cov-2, the, rbd, that, is, result, of, natural"
14552,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.130434783,"the, that, these, of, natural, sars-cov-2, is, it, as"
14553,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.130434783,"the, amino, between, sars-cov-2, and, to, be, in, other"
14554,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.130434783,"sars-cov-2, and, to, the, that, in"
14555,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.130434783,"the, of, sars-cov-2, is, to, it"
14556,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.130434783,"to, the, of, may, be, possible"
14557,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.130434783,"the, of, to, it, is, for"
14558,"zoonotic corona- 

viruses have become an increasing threat to human health,","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.130434783,"zoonotic, an, to"
14559,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.130434783,"the, was, and, that, a, of"
14560,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.130434783,"the, covid-19, in, to, seafood, of"
14561,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.130434783,"in, and, to, sars-cov-2, at, the"
14562,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.130434783,"this, of, the, market, in, that"
14563,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.130434783,"sequences, from, early, in, the, of"
14564,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.130434783,"bat, to, sars-cov-2"
14565,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.130434783,"the, has, a, of, to, with, that, from, and"
14566,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.130434783,"a, virus, from, the, it, is"
14567,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.130434783,"sars-cov-2, closely, related, to, in, a"
14568,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.130434783,"to, sars-cov-2, is, a, virus, the"
14569,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.130434783,"the, is, virus, to, a, of"
14570,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.130434783,"a, zoonotic, in, the, spillover, to"
14571,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.130434783,"the, of, and, more, likely, bats"
14572,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",Coronaviruses account for over 30% of the world’s viruses.,0.130434783,"for, the, of"
14573,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.130434783,"bats, and, as"
14574,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.130434783,"the, to, bat, and, that, sars-cov-2"
14575,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.130434783,"this, a, and, of, the, in"
14576,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.130434783,"a, of, viruses, in, and, the"
14577,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.130434783,"in, the, of, virus, for, is, to, that, with, and, this, a"
14578,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.130434783,"in, a, with, other, closely, related, and, which, are, similar, to, the"
14579,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.130434783,"sars-cov-2, is, related, to, bat, the"
14580,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.130434783,"bat, sars-cov-2, by, genome, at, the"
14581,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.130434783,"sars-cov-2, the, closest, at, similarity, to"
14582,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.130434783,"to, sars-cov-2, and, in, at, the"
14583,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.130434783,"and, the, to, similar, are, a, closely, related, with, other, in, which"
14584,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.130434783,"the, closely, related, to, sars-cov-2, in"
14585,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.130434783,"by, their, to, the, of, sars-cov-2"
14586,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.130434783,"the, rbd, and, that, of, is"
14587,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.130434783,"in, a, of, to, the, likely, virus, that, is, for, found, same"
14588,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.130434783,"for, the, of, that, virus, contained, a, found, in, sars, likely, to"
14589,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","This suggests that the BANAL series may be able to directly infect  

humans.",0.130434783,"may, be, the"
14590,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","This suggests that the BANAL series may be able to directly infect  

humans.",0.130434783,"may, that, this"
14591,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.130434783,"in, the, of, more, 2, is"
14592,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.130434783,"also, of, in, is, the, 2"
14593,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.130434783,"a, viruses, at, two, to, the"
14594,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.130434783,"and, the, which, cleavage, site, a"
14595,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.130434783,"bats, as, and"
14596,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.130434783,"in, the, virus, is, to, sars-cov-2"
14597,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.130434783,"in, closely, related, to, sars-cov-2, the"
14598,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.130434783,"closely, related, to, in, sars-cov-2, the"
14599,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.130434783,"it, is, that, sars-cov-2, the, through"
14600,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.130434783,"the, huanan, market, to, and, of"
14601,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.130434783,"a, of, to, by, the, and"
14602,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.130434783,"evidence, the, that, in, a, as, to, from, humans"
14603,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.130434783,"the, nucleotide, of, from, and, were, collected, in, with"
14604,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.130434783,"the, of, for, likely, in, found, a, virus, to, sars, that, contained"
14605,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.130434783,"and, the, likely, that, or, for, of, into, in, this, from, a"
14606,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.130434783,"the, of, evidence, this, that, a, virus, in, for"
14607,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.130434783,"the, to, in, a, for, of, one, researchers, presence, viruses, most, sars, bats, virus, were, yunnan, and, other"
14608,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.130434783,"in, a, of, researchers, one, to, yunnan, the, bats, for, presence, most, and, sars, viruses, were, other, virus"
14609,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.130434783,"a, and, were, to, of, in, the, huanan, market."
14610,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.130434783,"were, linked, to, a, and, in"
14611,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.130434783,"of, a, to, and, the, huanan, were, market., in"
14612,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.130434783,"evidence, the, a, to, spillover, market"
14613,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.130434783,"cases, and, the, huanan, seafood, zoonotic, spillover, of, a"
14614,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.130434783,"the, natural, is, and, to, of"
14615,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.130434783,"the, zoonotic, spillover, to, a, in"
14616,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.130434783,"and, at, the, that, zoonotic, spillover, in, this, a"
14617,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.130434783,"in, the, of, first, and, market"
14618,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.130434783,"the, of, is, with, and, but"
14619,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.130434783,"the, and, also, in, that, these, are, of, but"
14620,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.130434783,"for, the, of, and, that, into, from, a, in, this, likely, or"
14621,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.130434783,"the, cases, and, huanan, seafood, of, a, zoonotic, spillover"
14622,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.130434783,"at, a, zoonotic, and, this, in, the, spillover, that"
14623,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.130434783,"the, of, at, this, that, sars-cov-2, a, in, for"
14624,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","expended to make the simple point 

that COVID-19 had a natural origin.",0.130434783,"that, the, a"
14625,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.130434783,"bats, were, found, to, related, that"
14626,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.130434783,"of, and, viruses, a, in, the"
14627,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.130434783,"to, and, of, viruses, exist, in"
14628,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.130434783,"and, in, sars-cov-2, natural, origin, has"
14629,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.130434783,"that, not, virus., sars-cov-2, is, laboratory"
14630,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.130434783,"is, evidence, that, the, of, a"
14631,"a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.130434783,"a, coronavirus, sars-cov-2"
14632,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.130434783,"to, that, similarity, the, bats, of"
14633,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.130434783,"its, the, from, to, a, in"
14634,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.130434783,"the, of, rbd, to, that, sars-cov-2, is, result, natural"
14635,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.130434783,"that, the, of, a, near, and"
14636,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.130434783,"and, a, cleavage, site, the, which"
14637,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.130434783,"through, it, is, that, the, sars-cov-2"
14638,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.130434783,"the, of, is, sars-cov-2, that, features"
14639,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.130434783,"the, of, and, rbd, is, that"
14640,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",". In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.130434783,"., in, of, the, and, was"
14641,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.130434783,"the, genome, that, and, not, a"
14642,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.130434783,"the, of, genome, new, that, bat"
14643,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.130434783,"the, that, resembles, a, coronavirus, covid-19"
14644,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.130434783,"that, the, resembles, a, coronavirus, covid-19"
14645,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",The COVID-19 most likely developed from bat origin coronaviruses,0.130434783,"the, coronaviruses, from"
14646,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",The COVID-19 most likely developed from bat origin coronaviruses,0.130434783,"the, origin, from"
14647,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",The COVID-19 most likely developed from bat origin coronaviruses,0.130434783,"the, most, covid-19"
14648,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.130434783,"a, that, the, covid-19, is, of"
14649,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.130434783,"thus, that, the, origin, bat, or"
14650,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.130434783,"another, bat, the, of, animal, intermediate"
14651,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.130434783,"have, of, a, which, these, viruses"
14652,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.130434783,"of, the, covid-19, in, to, seafood"
14653,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.130434783,"bats, intermediate, and, the, in, china,"
14654,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.130434783,"to, that, in"
14655,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.130434783,"are, in, all"
14656,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.130434783,"to, be, in"
14657,"zoonotic corona- 

viruses have become an increasing threat to human health,","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.130434783,"viruses, an, to"
14658,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.130434783,"the, of, early, cases, that, in"
14659,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.130434783,"that, have, been, by, of, the"
14660,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.130434783,"bats, are, and, the, natural, of"
14661,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.130434783,"of, the, covid-19, patients, in, with"
14662,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.130434783,"with, the, of, in, province,, china"
14663,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.130434783,"was, that, the, of, to, it"
14664,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.130434783,"the, was, that, has, with, to"
14665,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.130434783,"that, not, to, it, first, in"
14666,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.130434783,"the, that, has, with, of, to"
14667,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.130434783,"the, of, to, that, was, not"
14668,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.130434783,"bats, the, have, known, as, of"
14669,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.130434783,"studies, in, china, the, of, these"
14670,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.130434783,"is, the, bat, in, by, from"
14671,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.130434783,"bats, an, intermediate, and, the, in"
14672,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.130434783,"was, isolated, and, in, were, at, a, market, china"
14673,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.130434783,"the, of, first, market, and, in"
14674,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.130434783,"have, their, origin, in, and, from"
14675,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.130434783,"the, have, been, from, in, and"
14676,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.130434783,"is, with, of, at, the, in"
14677,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.130434783,"the, in, bats, and, intermediate, china,"
14678,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.130434783,"an, intermediate, bats, and, in, the"
14679,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.130434783,"the, covid-19, a, of, that, and"
14680,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.130434783,"animals, is, of, the, covid-19, and"
14681,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.130434783,"of, that, the, covid-19, is, a"
14682,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.130434783,"from, the, which, wild, animals, for"
14683,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.130434783,"is, that, sars-cov-2, a, the, virus"
14684,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","zoonotic corona- 

viruses have become an increasing threat to human health,",0.130434783,"viruses, to, an"
14685,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.130434783,"the, of, virus, for, to, and"
14686,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.130434783,"first, not, to, it, that, in"
14687,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.130434783,"lab, the, that, has, been, but"
14688,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.130434783,"the, of, this, that, sars-cov-2, a, been, in, for"
14689,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.130434783,"of, the, was"
14690,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.130434783,"the, sars-cov-2, to, be, found, bat"
14691,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.130434783,"bat, cov, the"
14692,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.130434783,"was, the, bat"
14693,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.130434783,"sars-cov-2, to, be"
14694,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.130434783,"suggest, the, origin, of, virus, and"
14695,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.130434783,"of, the, that, are, natural, for"
14696,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.130434783,"these, as, the, of, it, that, sars-cov-2, is, natural"
14697,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.130434783,"the, to, sars-cov-2, by, of, their"
14698,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.130434783,"sars-cov-2, has, natural, origin, and, in"
14699,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.130434783,"the, is, by, bat, from, in"
14700,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.130434783,"that, sars-cov-2, was"
14701,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.130434783,"ratg13, from, sars-cov-2"
14702,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.130434783,"that, from, to"
14703,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.130434783,"has, been, but, that, the, lab"
14704,Originating from reservoir of bat,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.130434783,"from, of, bat"
14705,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.130434783,"this, consistent, with, and, subsequent, origin, of, the, in"
14706,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.130434783,"the, and, of, that, to, emergence"
14707,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.130434783,"to, is, be, that, and, the"
14708,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.130434783,"the, of, evidence, this, that, is"
14709,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.130434783,"the, that, sars-cov-2, and, from, a"
14710,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.130434783,"that, the, from, a, to, and"
14711,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.130434783,"that, the, sars-cov-2, and, coronavirus, from"
14712,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.130434783,"as, hosts, that, to, for, the"
14713,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.130434783,"of, to, the, which, that, virus"
14714,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.130434783,"the, of, to, that, which, virus"
14715,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.130434783,"bat, by, sars-cov-2, at, the, genome"
14716,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.130434783,"of, sequences, a, genome, bat, in"
14717,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.130434783,"a, bat, of, genome, sequences, in"
14718,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.130434783,"the, of, in, is, also, to"
14719,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.130434783,"is, also, 2, in, the, of"
14720,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.130434783,"is, the, and, similarity, for, sars-cov-2"
14721,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.130434783,"of, the, have, been, that, by"
14722,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.130434783,"we, sars-cov-2, the"
14723,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.130434783,"sars-cov-2, and, the, viruses, that, in"
14724,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.130434783,"bats, and, are, to, be, the"
14725,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.130434783,"are, viruses, to, the, that, and"
14726,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.130434783,"that, the, bat, is, only, at"
14727,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.130434783,"the, likely, more, of, bats, and"
14728,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.130434783,"the, from, that, sars-cov-2, and, coronavirus"
14729,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.130434783,"the, in, and, that, sars-cov-2, viruses"
14730,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.130434783,"to, sars-cov-2, is, originated, the, pangolin"
14731,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.130434783,"that, the, bat, origin, thus, or"
14732,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.130434783,"and, their, the, of, sars-cov-2, origin"
14733,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.130434783,"bat, and, the, origin, sars-cov-2, cluster"
14734,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.130434783,"the, is, sars-cov-2, that, pangolin, cov"
14735,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.130434783,"the, sars-cov-2, cluster, and, bat, origin"
14736,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.130434783,"and, in, patients, wuhan, china, on"
14737,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.130434783,"the, of, sequences, in, from, early"
14738,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.130434783,"these, studies, of, in, the, china"
14739,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.130434783,"and, suggest, origin, of, the, virus"
14740,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.130434783,"sars-cov-2, are, to, bat, pangolin, a"
14741,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.130434783,"the, are, of, bat, that, to"
14742,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.130434783,"to, sars-cov-2, a, that, the, pangolin"
14743,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.130434783,"of, the, genome, genomes, with, bat"
14744,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.130434783,"of, the, is, to, with, sars-cov-2"
14745,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.130434783,"and, of, sars-cov-2, is, the, to"
14746,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.130434783,"the, is, of, with, and, but"
14747,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.130434783,"analysis, the, recombination, for, transmission, and"
14748,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.130434783,"studies, the, of, and, have, that"
14749,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.130434783,"have, that, the, bats, and, a"
14750,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.130434783,"the, of, bats, a, for, and"
14751,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.130434783,"the, for, is, sars-cov-2, with, and"
14752,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.130434783,"and, similarity, sars-cov-2, is, the, for"
14753,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.130434783,"sars-cov-2, are, the"
14754,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.130434783,"that, virus, natural, for, and, the"
14755,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.130434783,"the, to, that, has, with, of"
14756,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.130434783,"that, pangolin-cov, with, the, of, to"
14757,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.130434783,"in, bat-, the, pangolin-covs, and, an"
14758,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.130434783,"and, of, it, that, in, bat"
14759,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.130434783,"the, was, not, to, that, of"
14760,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.130434783,"at, the, of, which, rbd, sars-cov-2"
14761,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.130434783,"is, that, of, sars-cov-2, the, features"
14762,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.130434783,"that, the, sars-cov-2, cov, pangolin, is"
14763,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.130434783,"is, the, to, in, rbd, of"
14764,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.130434783,"suggests, intermediate, host, pangolin, sars-cov-2, the"
14765,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.130434783,"suggests, the, sars-cov-2"
14766,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.130434783,"the, virus, that, has, similarity, to"
14767,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.130434783,"that, the, virus, has, to, of"
14768,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.130434783,"the, similarity, of, to, that, bats"
14769,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.130434783,"another, of, the, bat, animal, intermediate"
14770,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.130434783,"in, a, of, the, virus, that, this, is, for"
14771,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.130434783,"the, virus, has, is, that, of"
14772,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.130434783,"for, the, of, that, virus, a, in, this, evidence"
14773,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.130434783,"at, the, that, for, of, sars-cov-2, in, this, a"
14774,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.130434783,"this, for, the, of, that, sars-cov-2, been, in, a"
14775,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.130434783,"this, that, the, of, evidence, is"
14776,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.130434783,"the, human, from, animal, in, or"
14777,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.130434783,"that, the, sars-cov-2, or, covid-19, pandemic"
14778,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.130434783,"the, an, is, to, of, and"
14779,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.130434783,"the, is, to, of, and, it"
14780,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.130434783,"the, and, is, of, natural, to"
14781,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.130434783,"to, natural, the, of, and, is"
14782,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.130434783,"a, for, coronavirus, of, be, in, with, that, to"
14783,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.130434783,"is, bat, ratg13, to, the, in"
14784,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.130434783,"in, the, rbd, of, is, to"
14785,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.130434783,"the, that, of, are, and, these, in, but, also"
14786,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.130434783,"and, is, to, bat, in, of"
14787,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.130434783,"of, viruses, exist, in, and, to"
14788,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.130434783,"in, it, that, and, of, bat"
14789,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.130434783,"the, that, with, of, to, pangolin-cov"
14790,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.130136986,"by, the, of, a, in, species, to, that, sars, civets, as, and, direct, were, virus, similar, also, for, chinese"
14791,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.130136986,"in, the, sars, of, that, civets, for, as, chinese, also, virus, similar, to, species, were, by, a, and, direct"
14792,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.13,"the, was, isolate, virus, with, this, ace2, and, human, by, in, of, isolated"
14793,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.13,"and, the, of, to, a, bats, cave, with, that, in, recombination, events, result"
14794,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.13,"to, result, a, recombination, of, in, bats, the, cave, and, that, events, with"
14795,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.13,"human, ace2, and, by, this, virus, isolate, with, the, was, isolated, in, of"
14796,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.12987013,"widely, as, it, to, was, the, of, sars-cov-2, in, a"
14797,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.12987013,"in, the, was, a, at, that, from, humans, to, and"
14798,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.12987013,"in, the, of, virus, for, is, to, that, this, a"
14799,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.12987013,"in, the, of, virus, it, is, not, that, and, a"
14800,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.12987013,"evidence, the, that, of, samples, to, market., all, taken, market"
14801,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.12987013,"coronavirus, a, pangolin, and, with, reservoirs, intermediate, to, be, the"
14802,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.12987013,"in, a, of, to, the, virus, that, this, is, for"
14803,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.12987013,"a, the, of, and, in, it, virus, that, not, is"
14804,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.12987013,"and, the, it, that, for, of, sars-cov-2, in, this, a"
14805,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.12987013,"in, the, a, was, that, from, to, humans, at, and"
14806,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.12987013,"in, the, of, for, it, that, sars-cov-2, and, this, a"
14807,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.12987013,"to, the, of, evidence, market, samples, taken, all, that, market."
14808,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.12987013,"and, a, to, the, coronavirus, be, reservoirs, with, pangolin, intermediate"
14809,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.12987013,"as, a, of, the, in, was, it, widely, to, sars-cov-2"
14810,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.129770992,"the, infected, by, species, of, known, to, as, civets, and, raccoon, dog, in, badgers, ferret, may, also"
14811,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.129770992,"in, may, the, known, of, civets, as, raccoon, dog, ferret, badgers, also, to, species, infected, by, and"
14812,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.12962963,"the, that, evolved, infect, a, of, and"
14813,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.12962963,"identified, species, of, from, infected, by, and"
14814,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.12962963,"to, sars-cov-2, is, a, was, the, as"
14815,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.12962963,"the, is, of, sars-cov-2, to, a, in"
14816,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.12962963,"sars-cov-2, genetic, other, and, is, a, naturally"
14817,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.12962963,"naturally, occurring, have, in, other, of, coronaviruses"
14818,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.12962963,"t, is, highly, the, was, in, from"
14819,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.12962963,"the, that, sars-cov-2, is, a, virus, in"
14820,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.12962963,"sars-cov-2, and, a, genetic, is, other, naturally"
14821,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.12962963,"are, coronaviruses, to, these, the, bat, and"
14822,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.12962963,"bat, cov, and, the, same, sars-cov-2, ratg13"
14823,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.12962963,"in, analysis, of, which, that, similar, pangolin"
14824,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.12962963,"in, of, pangolin, sequences, and, which, similar"
14825,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.12962963,"that, a, was, the, and, is, to"
14826,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.12962963,"from, humans, the, of, sars-cov-2, to, spillover"
14827,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.12962963,"of, that, the, covid-19, is, origin, animal"
14828,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.12962963,"t, is, highly, was, from, the, in"
14829,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.12962963,"was, in, which, to, at, the, level"
14830,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.12962963,"and, the, of, to, that, sars-cov-2, is"
14831,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.12962963,"a, are, at, to, that, the, from"
14832,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.12962963,"a, that, the, was, to, and, in"
14833,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.12962963,"the, in, from, that, was, at, time"
14834,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.12962963,"in, to, is, of, the, has, bats"
14835,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.12962963,"the, of, sars-cov-2, to, is, this, evidence"
14836,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.12962963,"to, humans, be, through, of, in, bats"
14837,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.12962963,"studies, from, a, in, transmitted, to, and"
14838,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.12962963,"has, the, and, are, that, have, through"
14839,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.12962963,"the, a, that, are, from, to, at"
14840,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.12962963,"a, of, the, at, are, that, to"
14841,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.12962963,"explanation, for, the, of, animals, at, market"
14842,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.12962963,"to, that, the, of, and, more, than"
14843,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.12962963,"to, the, of, sars-cov-2, from, spillover, humans"
14844,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.12962963,"in, from, of, to, sars-cov-2, the, humans"
14845,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.12962963,"the, of, in, samples, from, early, that"
14846,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.12962963,"the, in, of, to, that, sars-cov-2, also"
14847,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.12962963,"of, the, two, in, that, sars-cov-2, a"
14848,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.12962963,"that, sars-cov-2, also, to, a, the, of"
14849,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.12962963,"that, was, to, laboratory, and, in, sars-cov-2"
14850,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.12962963,"it, in, a, two, to, the, genome"
14851,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.12962963,"the, was, a, that, about, and, to"
14852,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.12962963,"is, that, the, of, to, sars-cov-2, pandemic"
14853,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.12962963,"the, explanation, for, of, animals, at, market"
14854,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.12962963,"that, a, was, the, and, to, about"
14855,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.12962963,"from, seafood, that, the, virus, is, were"
14856,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.12962963,"and, of, which, is, an, the, to"
14857,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.12962963,"as, a, the, was, is, to, sars-cov-2"
14858,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.12962963,"is, that, sars-cov-2, a, the, virus, from"
14859,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.12962963,"of, to, a, genome, which, from, bat"
14860,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.12962963,"have, the, genetic, and, virus, to, that"
14861,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.12962963,"the, has, to, bats, in, of, is"
14862,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.12962963,"the, is, virus, and, in, that, to"
14863,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.12962963,"into, and, together, with, bat, cov, the"
14864,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.12962963,"and, human, a, natural, of, the, is"
14865,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.12962963,"the, is, to, previously, used, for, sars-cov"
14866,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.12962963,"is, and, it, that, sars-cov-2, to, by"
14867,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.12962963,"the, for, to, is, previously, used, sars-cov"
14868,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.12962963,"analysis, of, to, the, and, for, was"
14869,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.12962963,"genetic, have, that, the, virus, and, to"
14870,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.12962963,"is, between, and, that, of, sars-cov-2, to"
14871,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.12962963,"to, from, of, in, bats, the, coronaviruses"
14872,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.12962963,"been, in, the, and, to, may, have"
14873,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.12962963,"it, that, sars-cov-2, and, to, is, by"
14874,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.12962963,"between, sars-cov-2, and, of, is, to, that"
14875,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.12962963,"the, and, coronaviruses, that, viruses, are, to"
14876,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.12962963,"a, of, the, with, sars-cov, and, novel"
14877,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.12962963,"the, of, a, to, bats, with, acting, as, intermediate, amplifying, and, transmitting, or, coronaviruses"
14878,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.12962963,"a, of, natural, reservoirs, and, to, the"
14879,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.12962963,"the, and, a, host,, palm, dromedary, camels"
14880,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.12962963,"the, of, viruses,, related, to, as, bat"
14881,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.12962963,"transmitted, from, to, a, studies, and, in"
14882,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.12962963,"on, identified, in, a, isolated, that, were"
14883,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.12962963,"the, of, from, with, a, and, sars-cov-2"
14884,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.12962963,"of, the, sars-cov-2, isolated, in, from, and"
14885,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.12962963,"that, isolated, identified, in, were, a, on"
14886,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.12962963,"sars-cov, and, a, novel, the, of, with"
14887,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.12962963,"in, similar, to, that, of, the, gene"
14888,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.12962963,"a, of, and, that, the, evolved, infect"
14889,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.12962963,"it, is, that, a, the, of, virus"
14890,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.12962963,"et, a, of, to, ratg13,, the, sars-cov-2"
14891,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.12962963,"the, that, many, of, and, within, in"
14892,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.12962963,"have, of, in, other, coronaviruses, naturally, occurring"
14893,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.12962963,"analysis, that, similar, of, in, which, pangolin"
14894,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.12962963,"virus, in, similar, sars-cov-2, the, sequence, of"
14895,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.12962963,"to, of, that, similar, related, ratg13, in"
14896,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.12962963,"a, of, in, the, and, has, been"
14897,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.12962963,"intermediate, host, a, in, with, sars-cov-2, the"
14898,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.12962963,"that, the, of, sars-cov-2, pandemic, is, to"
14899,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.12962963,"a, and, this, in, the, that, to"
14900,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.12962963,"this, to, that, the, of, and, is"
14901,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.12962963,"a, intermediate, host, sars-cov-2, with, the, in"
14902,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.12962963,"the, sars-, cov-2, is, from, species, in"
14903,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.12962963,"from, in, humans, the, of, sars-cov-2, to"
14904,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.12962963,"the, of, and, to, rbd, is, that"
14905,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.12962963,"it, is, that, the, sars-cov-2, as, to"
14906,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.12962963,"the, of, that, serve, as, hosts, for"
14907,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.12962963,"that, has, have, through, and, are, the"
14908,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.12962963,"the, have, been, in, to, and, may"
14909,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.12962963,"that, was, sars-cov-2, to, and, in, laboratory"
14910,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.12962963,"by, and, to, the, of, sars-cov-2, is"
14911,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.12962963,"is, to, the, by, between, and, be"
14912,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.12962963,"in, the, was, that, from, at, time"
14913,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.12962963,"samples, from, early, in, the, of, that"
14914,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.12962963,"the, of, in, to, coronaviruses, from, bats"
14915,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.12962963,"sars-cov-2, is, a, virus, that, from, the"
14916,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.12962963,"the, is, that, virus, a, of, it"
14917,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.12962963,"a, of, the, in, is, to, sars-cov-2"
14918,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.12962963,"in, a, closely, related, to, sars-cov-2, the"
14919,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.12962963,"a, of, sars-cov-2, in, is, the, to"
14920,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.12962963,"the, of, closely, to, as, genetic, bat"
14921,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.12962963,"at, the, level, to, which, was, in"
14922,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.12962963,"the, in, a, genome, it, to, two"
14923,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.12962963,"the, sars-cov-2, to, a, closely, related, in"
14924,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.12962963,"at, are, a, and, in, the, to"
14925,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.12962963,"the, sars-cov-2, are, to, a, with, genome"
14926,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.12962963,"and, the, of, rbd, to, that, is"
14927,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.12962963,"the, of, to, bat, viruses,, as, related"
14928,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.12962963,"the, of, bat, as, closely, to, genetic"
14929,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.12962963,"the, and, are, bat, coronaviruses, these, to"
14930,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.12962963,"are, a, and, in, the, events, to"
14931,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.12962963,"coronaviruses, and, a, to, the, bats, of, with, or, acting, as, intermediate, amplifying, transmitting"
14932,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.12962963,"and, a, of, between, is, the, to"
14933,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.12962963,"in, the, to, that, and, this, a"
14934,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.12962963,"in, a, and, are, to, at, the"
14935,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.12962963,"are, a, to, events, in, the, and"
14936,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.12962963,"the, many, in, and, that, within, of"
14937,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.12962963,"the, and, which, to, a, of, in"
14938,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.12962963,"and, a, to, the, natural, reservoirs, of"
14939,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.12962963,"the, sars-cov-2, to, evidence, of, this, is"
14940,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.12962963,"of, that, the, serve, as, hosts, for"
14941,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.12962963,"in, also, the, of, that, sars-cov-2, to"
14942,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.12962963,"a, sars-cov-2, and, with, the, of, from"
14943,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.12962963,"the, of, that, animal, is, origin, covid-19"
14944,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.12962963,"analysis, the, was, to, of, for, and"
14945,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.12962963,"have, been, in, to, the, of, has"
14946,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.12962963,"sars-, cov-2, from, is, in, species, the"
14947,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.12962963,"to, humans, bats, through, in, of, be"
14948,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.12962963,"sars-cov-2, and, the, of, isolated, from, in"
14949,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.12962963,"in, the, of, sequence, sars-cov-2, similar, virus"
14950,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.12962963,"xiao, et, al., that, by, a, of, virus, with, one, to, and, pangolins, the"
14951,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.12962963,"identified, from, of, species, infected, by, and"
14952,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.12962963,"that, the, hosts, a, of, and, mers-cov"
14953,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.12962963,"a, are, at, to, that, the, of"
14954,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.12962963,"suggest, that, a, origin, of, the, virus"
14955,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.12962963,"of, a, suggest, that, the, virus, to"
14956,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.12962963,"a, the, natural, of, is, and, human"
14957,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.12962963,"a, of, the, that, suggest, origin, virus"
14958,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.12962963,"the, that, scenario, of, natural, genetic, is"
14959,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.12962963,"genetic, that, natural, of, the, is, scenario"
14960,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.12962963,"that, for, sars-cov-2, they, are, an, with"
14961,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.12962963,"that, sars-cov-2, are, also, hypothesis, the, of"
14962,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.12962963,"the, of, sars-cov-2, to, is, and, by"
14963,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.12962963,"the, to, have, has, been, in, of"
14964,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.12962963,"the, to, be, is, and, between, by"
14965,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.12962963,"the, of, is, to, that, and, this"
14966,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.12962963,"that, a, pangolin, to, and, the, sars-cov-2"
14967,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.12962963,"that, were, from, the, seafood, virus, is"
14968,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.12962963,"as, the, to, it, that, sars-cov-2, is"
14969,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.12962963,"a, of, the, that, suggest, to, virus"
14970,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.12962963,"a, genome, of, which, to, from, bat"
14971,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.12962963,"the, an, which, is, to, of, and"
14972,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.12962963,"the, between, and, is, of, a, to"
14973,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.12962963,"sars-cov-2, is, to, in, the, ratg13, which"
14974,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.12962963,"the, of, sars-cov-2, genomes, to, a, ratg13"
14975,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.12962963,"the, of, sars-cov-2, is, a, in, for"
14976,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.12962963,"sequences, and, similar, of, in, which, pangolin"
14977,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.12962963,"that, are, with, sars-cov-2, they, an, for"
14978,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.12962963,"ratg13,, the, to, sars-cov-2, of, a, et"
14979,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.12962963,"the, pangolins, and, with, by, of, a, to, et, al., xiao, that, one, virus"
14980,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.12962963,"the, that, sars-cov-2, to, a, and, pangolin"
14981,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.12962963,"in, two, the, of, that, a, sars-cov-2"
14982,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.12962963,"the, that, sars-cov-2, is, part, of, sarbecovirus"
14983,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.12962963,"on, genome, in, the, based, these, and"
14984,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.12962963,"together, with, bat, cov, and, into, the"
14985,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.12962963,"sars-cov-2, ratg13, in, which, is, the, to"
14986,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.12962963,"that, sars-cov-2, is, part, of, the, sarbecovirus"
14987,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.12962963,"the, bat, cov, ratg13, and, sars-cov-2, same"
14988,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.12962963,"these, based, on, the, genome, in, and"
14989,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.12962963,"also, the, of, that, a, sars-cov-2, to"
14990,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.12962963,"the, that, are, also, of, sars-cov-2, hypothesis"
14991,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.12962963,"a, with, are, to, sars-cov-2, the, genome"
14992,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.12962963,"a, of, sars-cov-2, ratg13, the, genomes, to"
14993,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.12962963,"and, a, the, palm, dromedary, camels, host,"
14994,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.12962963,"the, a, of, mers-cov, that, hosts, and"
14995,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.12962963,"is, that, sars-cov-2, a, the, virus, in"
14996,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.12962963,"a, of, sars-cov-2, in, is, the, for"
14997,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.12962963,"found, that, with, of, suggesting, may, to"
14998,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.12962963,"the, of, that, gene, in, similar, to"
14999,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.12962963,"in, of, that, related, to, ratg13, similar"
15000,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.12962963,"of, found, to, with, suggesting, that, may"
15001,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.129411765,"in, the, of, as, an, host, a, that, virus, to, and"
15002,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.129411765,"a, as, the, of, virus, and, in, that, to, an, host"
15003,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.129411765,"a, was, at, market, in, china, the, virus, to, of, were"
15004,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.129411765,"the, of, china, a, to, in, market, were, virus, at, was"
15005,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.129251701,"the, and, for, of, a, to, that, were, in, is, sars, live, animal, palm, infected, than, by, at, market"
15006,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.129251701,"in, than, the, sars, live, animal, of, that, palm, for, at, market, to, were, infected, by, a, is, and"
15007,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.129032258,"the, sars, bats, are"
15008,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.129032258,"are, and, be, to"
15009,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.129032258,"species, of, the, reservoir"
15010,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.129032258,"sars-cov, and, to, bat"
15011,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.129032258,"and, similar, to, sars-cov-2."
15012,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.129032258,"to, and, sars-cov, in"
15013,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.129032258,"sars-cov-2, to, its, in"
15014,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.129032258,"it, was, in, a, with, to, sars-cov-2, the"
15015,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.129032258,"the, of, be, to, have, between, and, sars-cov-2"
15016,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.129032258,"the, insertion, in, sars-cov-2, amino, acid, coronaviruses, be"
15017,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.129032258,"a, is, to, spike, in, the, which, human"
15018,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.129032258,"sars-cov-2, that, identical, to"
15019,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.129032258,"has, been, of, bat"
15020,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.129032258,"are, viruses, the, and"
15021,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.129032258,"and, variety, the, of"
15022,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.129032258,"most, to, of, sars-cov-2"
15023,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.129032258,"the, between, sars-cov-2, and, have, to, be, of"
15024,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.129032258,"has, used, that, in"
15025,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.129032258,"evolution,, receptor, and, that, is, bats, recombination, of"
15026,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.129032258,"in, an, ace2, of, bats, to, and, the"
15027,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.129032258,"to, that, in, bats,"
15028,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.129032258,"the, was, to, 96.2%"
15029,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.129032258,"in, a, and, market"
15030,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.129032258,"coronavirus, is, and, to"
15031,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.129032258,"an, to, and, be"
15032,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.129032258,"the, sars-, cov,, and"
15033,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.129032258,"bats, be, the, hosts"
15034,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.129032258,"natural, and, are, the"
15035,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.129032258,"the, of, and, bats"
15036,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.129032258,"species, and, that, the, as, intermediate, hosts, for"
15037,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.129032258,"that, and, intermediate, hosts, for, transmission, to, the"
15038,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.129032258,"the, shares, identity, with"
15039,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.129032258,"coronavirus, is, from, to"
15040,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.129032258,"the, sars-cov-2, to, coronavirus"
15041,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.129032258,"is, sars-cov-2, the, from"
15042,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.129032258,"the, sars-cov-2, is, a"
15043,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.129032258,"is, the, with, sars-cov-2"
15044,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.129032258,"in, the, was, to"
15045,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.129032258,"was, and, to, the"
15046,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.129032258,"the, regions, to, in, and, animals, sars-cov, was"
15047,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.129032258,"in, was, to, the"
15048,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.129032258,"the, from, in, china"
15049,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.129032258,"that, the, of, lineage"
15050,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.129032258,"the, of, sars-cov-2, in"
15051,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.129032258,"of, the, in, that"
15052,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.129032258,"that, sars-cov-2, the, bat"
15053,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.129032258,"bat, the, of, sars-cov-2"
15054,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.129032258,"bat, to, sars-cov, and"
15055,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.129032258,"bat, with, to, sars-cov-2"
15056,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.129032258,"the, sars, are, bats"
15057,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.129032258,"the, of, are, that"
15058,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","with the first case being linked to  

a seafood market",0.129032258,"to, the, a, with"
15059,"this one jumped from bats origin  

into humans","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.129032258,"this, from, bats, humans"
15060,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.129032258,"the, zoonotic, in, and"
15061,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.129032258,"zoonotic, the, that, and"
15062,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.129032258,"a, in, the, that"
15063,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.129032258,"hypothesis, that, was, the"
15064,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.129032258,"evidence, that, sars-cov-2, a"
15065,"Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.129032258,"from, the, hypothesis, as"
15066,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.129032258,"are, and, the, natural"
15067,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.129032258,"hypothesis, that, the, was"
15068,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.129032258,"the, of, sars-cov-2, into"
15069,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.129032258,"the, sars-cov-2, was, that"
15070,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.129032258,"of, that, the, was"
15071,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.129032258,"bat, closer, to, sars-cov-2"
15072,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.129032258,"in, a, we, that, the, two, lineage, are"
15073,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.129032258,"a, of, viruses, in, their, and, which, the"
15074,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.129032258,"sars-cov-2, the, of, into"
15075,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.129032258,"that, sars-cov-2, through, of"
15076,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.129032258,"that, are, to, be"
15077,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.129032258,"that, sars-cov-2, to, be"
15078,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.129032258,"and, to, be, that, the, of, are, sars-cov-2"
15079,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.129032258,"a, the, lineage, we, that, are, two, in"
15080,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.129032258,"that, are, to, in"
15081,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.129032258,"that, sars-cov-2, was, the"
15082,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.129032258,"sars-cov-2, was, that, and"
15083,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.129032258,"the, in, sars-cov-2, and"
15084,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.129032258,"that, sars-cov-2, emerged, a"
15085,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.129032258,"sars-cov-2, a, that, in"
15086,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.129032258,"is, that, the, virus, was, as, of, a"
15087,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.129032258,"this, a, that, the, covid-19, is, of, wild"
15088,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.129032258,"that, to, originated, in"
15089,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.129032258,"have, that, the, to, infected, animals, at, market"
15090,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.129032258,"such, as, and, birds,"
15091,"a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.129032258,"a, coronavirus, similarity, with"
15092,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.129032258,"the, virus, and, were"
15093,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.129032258,"from, is, and, the"
15094,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.129032258,"that, to, a, zoonotic"
15095,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.129032258,"the, host, of, and"
15096,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.129032258,"is, to, coronavirus, and"
15097,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.129032258,"to, coronavirus, from, is"
15098,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.129032258,"studies, that, very, to"
15099,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.129032258,"the, was, as, of"
15100,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.129032258,"a, in, of, with"
15101,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.129032258,"the, of, with, in"
15102,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.129032258,"a, market, in, that, the, to, of, were"
15103,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.129032258,"to, sars-cov-2, from, a, bats, the, and, that"
15104,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Bats have been reported as being the rich source of 

coronaviruses",0.129032258,"of, bats, reported, the"
15105,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.129032258,"sars-cov-2, from, to, the"
15106,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.129032258,"the, sars-cov-2, coronavirus, to"
15107,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.129032258,"the, coronavirus, has, with"
15108,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.129032258,"sars-cov-2, of, the, and, with, similar, to, protein"
15109,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.129032258,"sars-cov-2, with, bat, the"
15110,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.129032258,"has, the, with, identity"
15111,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.129032258,"has, suggested, that, sars-cov-2"
15112,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.129032258,"that, sars-cov-2, to, originated"
15113,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.129032258,"of, the, and, is"
15114,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.129032258,"pangolin, and, the, of"
15115,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.129032258,"studies, that, the, sequences, of, sars-cov-2, and, which"
15116,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.129032258,"from, a, virus, in"
15117,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.129032258,"have, to, the, infected, animals, at, market, that"
15118,"This suggests that the BANAL series may be able to directly infect  

humans.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.129032258,"that, the, may, to"
15119,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.129032258,"the, is, of, covid-19, are, and, in, but"
15120,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.129032258,"in, that, has, used"
15121,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.129032258,"that, covid-19, has, to"
15122,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.129032258,"show, that, to, in"
15123,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.129032258,"a, of, the, virus, that, was, is, as"
15124,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.129032258,"the, was, of, as"
15125,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.129032258,"the, of, as, a"
15126,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.129032258,"evidence, that, the, of"
15127,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.129032258,"sars-cov, and, in, to"
15128,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.129032258,"that, in, the, virus"
15129,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.129032258,"the, that, and, is"
15130,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.129032258,"the, its, is, similar"
15131,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.129032258,"origin, and, in, animal"
15132,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.129032258,"the, together, with, and"
15133,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.129032258,"identity, to, and, be"
15134,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.129032258,"and, that, the, of"
15135,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.129032258,"the, have, been, in"
15136,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.129032258,"the, virus, that, in"
15137,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.129032258,"the, that, not, in"
15138,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.129032258,"to, the, coronavirus, sars-cov-2"
15139,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.129032258,"the, of, coronavirus, to"
15140,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.129032258,"genome, to, the, of"
15141,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.129032258,"of, the, reported, been"
15142,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.129032258,"of, bat, genome, sars-cov-2"
15143,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.129032258,"sars-cov-2, has, the, bat"
15144,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.129032258,"to, the, of, sars-cov-2"
15145,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.129032258,"of, are, the, reservoir"
15146,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.129032258,"bat, has, been, of"
15147,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.129032258,"coronaviruses, are, the, that"
15148,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.129032258,"of, the, that, coronaviruses"
15149,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.129032258,"that, the, of, human"
15150,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.129032258,"from, viruses, are, nearly"
15151,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.129032258,"the, critical, are, in"
15152,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.129032258,"bats, evolution,, recombination, of, is, and, that, receptor"
15153,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.129032258,"bats, the, reservoir, which"
15154,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.129032258,"covid-19, virus, most, the"
15155,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.129032258,"which, in, has, the"
15156,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.129032258,"a, zoonotic, that, to"
15157,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.129032258,"virus, that, is, to"
15158,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.129032258,"is, the, virus, a"
15159,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.129032258,"from, to, the, virus"
15160,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.129032258,"a, the, is, animals"
15161,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.129032258,"from, the, to, sars-cov-2"
15162,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.129032258,"closely, related, sars-cov-2, bats"
15163,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.129032258,"the, closely, related, to"
15164,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.129032258,"is, to, of, the"
15165,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.129032258,"the, of, to, in"
15166,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.129032258,"the, outbreak, is, of"
15167,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.129032258,"the, of, coronaviruses, to"
15168,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.129032258,"evidence, and, that, sars-cov-2"
15169,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.129032258,"the, from, sars-cov-2, is"
15170,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.129032258,"the, that, lineage, of"
15171,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.129032258,"the, of, to, coronavirus"
15172,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.129032258,"of, the, that, virus"
15173,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.129032258,"the, genome, of, to"
15174,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.129032258,"to, the, of, virus"
15175,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.129032258,"the, of, with, to"
15176,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.129032258,"the, and, zoonotic, in"
15177,"insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.129032258,"such, as, birds,, and"
15178,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.129032258,"are, the, and, viruses"
15179,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.129032258,"the, are, and, to"
15180,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.129032258,"that, the, coronaviruses, are"
15181,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.129032258,"the, and, viruses, to"
15182,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.129032258,"are, zoonotic, and, to"
15183,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.129032258,"coronavirus, the, to, sars-cov-2"
15184,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.129032258,"that, the, of, coronaviruses"
15185,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.129032258,"coronavirus, the, has, with"
15186,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.129032258,"has, to, that, covid-19"
15187,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.129032258,"in, to, sars-cov-2, protein"
15188,"All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.129032258,"that, in, a, sars-cov-2"
15189,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.129032258,"virus, from, a, in"
15190,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.129032258,"virus, that, is, bat"
15191,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.129032258,"a, based, on, the, in, protein, from, pangolin"
15192,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.129032258,"these, based, on, the, in, that, hosts, for"
15193,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.129032258,"together, with, and, the"
15194,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.129032258,"and, bat, ratg13, to, the, viruses, that, in"
15195,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.129032258,"bats, to, be, the"
15196,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Bats are natural hosts of many of the known  

coronaviruses",0.129032258,"the, known, of, natural"
15197,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.129032258,"sars-cov-2, to, species, may, be, is, and, between"
15198,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.129032258,"studies, the, of, and, sequences, that, sars-cov-2, which"
15199,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.129032258,"is, most, to, the"
15200,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.129032258,"sars-cov-2, has, a, similarity"
15201,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.129032258,"the, was, in, to"
15202,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.129032258,"the, a, that, in"
15203,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.129032258,"coronavirus, in, the, with"
15204,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.129032258,"the, that, a, of"
15205,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.129032258,"a, of, that, the"
15206,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.129032258,"a, of, the, that"
15207,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.129032258,"a, of, results, the"
15208,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.129032258,"the, of, that, these"
15209,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.129032258,"be, that, the, of"
15210,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.129032258,"the, was, and, to"
15211,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.129032258,"bats, to, and, the"
15212,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.129032258,"the, of, was, and"
15213,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.129032258,"sars-cov-2, the, and, cov"
15214,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.129032258,"was, also, the, in"
15215,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.129032258,"sars-cov-2, closely, related, bats"
15216,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.129032258,"reservoir, of, that, the"
15217,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.129032258,"between, sars-cov-2, and, pangolin"
15218,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.129032258,"sars-cov-2, pangolin, and, a"
15219,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.129032258,"of, sites, in, been"
15220,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.129032258,"sites, been, in, of"
15221,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.129032258,"the, as, of, a"
15222,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.129032258,"the, of, ratg13, sars-cov-2"
15223,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.129032258,"a, natural, origin, of"
15224,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.129032258,"the, of, sars-cov-2, natural"
15225,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.129032258,"sars-cov-2, the, origin, ratg13"
15226,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","this one jumped from bats origin  

into humans",0.129032258,"humans, from, bats, this"
15227,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.129032258,"the, to, human, than"
15228,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.129032258,"the, zoonotic, and, of"
15229,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.129032258,"bat, the, of, and"
15230,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.129032258,"a, has, similarity, sars-cov-2"
15231,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.129032258,"the, for, were, in"
15232,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.129032258,"sars-cov-2, a, the, cov"
15233,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.129032258,"that, in, the, not"
15234,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.129032258,"research, that, in, sars-cov-2"
15235,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.129032258,"the, to, is, that"
15236,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.129032258,"sars-cov-2, not, that, the"
15237,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.129032258,"it, is, that, sars-cov-2, a, the, of, virus"
15238,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.129032258,"it, in, a, with, and, to, sars-cov-2, the"
15239,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.129032258,"in, the, of, is, to, sars-cov-2, that, pangolin"
15240,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.129032258,"a, coronavirus, with, similarity"
15241,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.129032258,"a, shared, with, sars-cov-2"
15242,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.129032258,"that, in, research, sars-cov-2"
15243,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.129032258,"discovered, that, the, sars-cov-2"
15244,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.129032258,"the, that, sars-cov-2, to"
15245,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.129032258,"the, to, that, sars-cov-2"
15246,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.129032258,"the, is, generally, and"
15247,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.129032258,"the, sars-cov-2, in, of"
15248,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.129032258,"the, of, in, to"
15249,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.129032258,"the, of, sars-cov-2, ratg13"
15250,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.129032258,"the, of, has, in"
15251,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.129032258,"in, the, of, sars-cov-2"
15252,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","bats are also important reservoir species for a great 

range of coronaviruses",0.129032258,"of, bats, reservoir, for"
15253,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.129032258,"bats, the, of, and, in, to, ace2, an"
15254,"Bats have been reported as being the rich source of 

coronaviruses","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.129032258,"bats, reported, the, of"
15255,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.129032258,"s, sequence, with, banal-20-52"
15256,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.129032258,"s, banal-20-52, sequence, with"
15257,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.129032258,"that, of, with, than"
15258,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.129032258,"the, amino, acid, insertion, sars-cov-2, be, in, coronaviruses"
15259,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.129032258,"nucleotide, to, therefore, be"
15260,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.129032258,"in, laos, by, and, similar, to, at, the"
15261,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.129032258,"the, of, sars-cov-2, to, be, it, is, and"
15262,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.129032258,"as, intermediate, hosts, that, for, and, the, species"
15263,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.129032258,"in, a, of, for, sars-cov-2, with, that, may"
15264,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.129032258,"intermediate, hosts, that, transmission, to, for, and, the"
15265,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.129032258,"in, for, sars-cov-2, to, be, with, that, may"
15266,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.129032258,"sars-cov-2, is, between, and, species, be, to, may"
15267,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.129032258,"and, the, of, to, it, be, sars-cov-2, is"
15268,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.129032258,"a, an, host, zoonotic"
15269,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.129032258,"the, sars-cov-2, and, animal"
15270,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.129032258,"sars-cov-2, with, to, bat"
15271,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan",0.129032258,"presence, of, dogs, in"
15272,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.129032258,"to, sars-cov-2, a, that, from, bats, and, the"
15273,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.129032258,"the, which, reservoir, bats"
15274,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.129032258,"the, of, virus, it, is, that, sars-cov-2, a"
15275,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.129032258,"of, sars-cov-2, which, the"
15276,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.129032258,"sars-cov-2, coronaviruses, the, of"
15277,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.129032258,"animal, and, the, of"
15278,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.129032258,"most, of, sars-cov-2, to"
15279,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.129032258,"the, as, intermediate, sars-cov-2"
15280,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.129032258,"in, are, and, all, sars-cov-2, bat, that, the"
15281,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.129032258,"that, the, most, sars-cov-2"
15282,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.129032258,"were, the, and, virus"
15283,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.129032258,"to, closely, related, the"
15284,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.129032258,"viruses, to, the, and"
15285,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.129032258,"were, for, the, in"
15286,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.129032258,"the, southern, china, to, in, and, were, virus"
15287,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.129032258,"the, of, variety, and"
15288,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.129032258,"of, that, the, covid-19, bat, a, species, as"
15289,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.129032258,"a, the, in, was, it, to, with, sars-cov-2"
15290,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.129032258,"in, the, it, to, sars-cov-2, with, and, a"
15291,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.129032258,"at, the, and, in, laos, similar, to, by"
15292,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.129032258,"similar, to, and, sars-cov-2."
15293,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.129032258,"a, of, in, that, for, sars, by, the, to, virus, closely, related"
15294,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.129032258,"with, than, that, of"
15295,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","This suggests that the BANAL series may be able to directly infect  

humans.",0.129032258,"may, the, to, that"
15296,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.129032258,"the, is, similar, its"
15297,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.129032258,"the, of, closely, related, by, for, in, a, virus, to, sars, that"
15298,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.129032258,"the, covid-19, in, and, to, wuhan, december, of"
15299,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.129032258,"that, more, than, among, the, sars-cov-2, to, suggesting, by, be, associated, with, in, this, of, and"
15300,"Bats are natural hosts of many of the known  

coronaviruses","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.129032258,"natural, of, the, known"
15301,Genetic evidence suggesting otherwise is yet to be presented.,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.129032258,"evidence, suggesting, is, to"
15302,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.129032258,"are, in, but, is, of, the, covid-19, and"
15303,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.129032258,"of, the, cases, in, that, market,, was, by"
15304,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","expended to make the simple point 

that COVID-19 had a natural origin.",0.129032258,"the, a, that, to"
15305,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","expended to make the simple point 

that COVID-19 had a natural origin.",0.129032258,"that, the, covid-19, to"
15306,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","expended to make the simple point 

that COVID-19 had a natural origin.",0.129032258,"the, to, covid-19, a"
15307,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.129032258,"the, hypothesis, as, from"
15308,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.129032258,"a, of, the, and, in, which, viruses, their"
15309,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.129032258,"results, the, a, of"
15310,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.129032258,"and, origin, in, animal"
15311,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.129032258,"a, zoonotic, an, host"
15312,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.129032258,"in, humans, an, animal"
15313,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.129032258,"the, discovered, that, sars-cov-2"
15314,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.129032258,"the, sars-cov-2, 96.2%, bat"
15315,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.129032258,"sars-cov-2, not, that, a"
15316,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.129032258,"through, that, sars-cov-2, of"
15317,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.129032258,"a, that, sars-cov-2, emerged"
15318,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.129032258,"a, of, that, sars-cov-2"
15319,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.129032258,"a, of, sars-cov-2, that"
15320,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.129032258,"one, several, of, the"
15321,"bats are also important reservoir species for a great 

range of coronaviruses","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.129032258,"bats, reservoir, for, of"
15322,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.129032258,"the, spike, which, to, a, is, in, human"
15323,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.129032258,"from, that, to, and"
15324,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.129032258,"analysis, the, from, and"
15325,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.129032258,"that, the, of, bat, species, covid-19, as, a"
15326,"results suggest that the pan- 

golin may be a long-term host of these pathogens.",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.129032258,"that, the, of, these"
15327,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.129032258,"of, covid-19, december, to, wuhan, and, the, in"
15328,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.129032258,"are, a, of, including"
15329,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.129032258,"and, are, to, be"
15330,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.129032258,"are, zoonotic, to, and"
15331,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.129032258,"in, that, are, to"
15332,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.129032258,"that, originated, in, to"
15333,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.129032258,"in, an, animal, humans"
15334,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.129032258,"is, the, to, in"
15335,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.129032258,"the, in, market, to"
15336,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.129032258,"is, the, to, covid-19"
15337,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.129032258,"the, to, covid-19, is"
15338,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.129032258,"the, that, in, of"
15339,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.129032258,"in, the, have, been"
15340,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.129032258,"the, of, been, in"
15341,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.129032258,"cases, the, market,, that, was, of, in, by"
15342,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.129032258,"was, by, the, of, that, have, been, in"
15343,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.129032258,"that, in, the, of"
15344,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.129032258,"the, virus, covid-19, most"
15345,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.129032258,"the, is, to, most"
15346,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.129032258,"the, to, have, that, been, in, of, animals"
15347,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.129032258,"viruses, of, the, have, been, in, sunda, and"
15348,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.129032258,"in, the, of, with"
15349,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.129032258,"to, the, have, been, in, of, that, animals"
15350,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.129032258,"of, species, the, reservoir"
15351,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.129032258,"one, of, the, several"
15352,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.129032258,"the, is, rhinolophus, species"
15353,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.129032258,"the, in, from, china"
15354,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.129032258,"is, species, rhinolophus, the"
15355,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.129032258,"from, the, and, is"
15356,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.129032258,"and, to, bats, the"
15357,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.129032258,"the, has, been, as, species, of, to, civets, infected, by, such, and"
15358,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.129032258,"the, sars-cov, was, in, and, to, animals, regions"
15359,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.129032258,"the, virus, and, to, were, in, southern, china"
15360,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.129032258,"a, and, market, in"
15361,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.129032258,"was, and, the, of"
15362,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.129032258,"in, was, of, the"
15363,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.129032258,"viruses, the, have, been, in, of, and, sunda"
15364,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.129032258,"a, of, the, that, covid-19, this, is, wild"
15365,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.129032258,"a, animals, the, is"
15366,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.129032258,"the, of, outbreak, is"
15367,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.129032258,"is, that, the, and"
15368,"expended to make the simple point 

that COVID-19 had a natural origin.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.129032258,"to, the, covid-19, a"
15369,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.129032258,"the, infected, by, species, of, to, such, as, civets, and, has, been"
15370,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.129032258,"the, disease, and, in"
15371,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.129032258,"the, generally, and, is"
15372,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.129032258,"is, bats, the, very"
15373,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.129032258,"that, the, virus, of"
15374,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.129032258,"to, of, and, the"
15375,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.129032258,"natural, origin, of, a"
15376,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.129032258,"the, that, not, sars-cov-2"
15377,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.129032258,"that, sars-cov-2, not, a"
15378,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.129032258,"of, the, have, been, in, that, was, by"
15379,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.129032258,"the, sars-cov-2, was, of"
15380,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.129032258,"the, to, 96.2%, was"
15381,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.129032258,"the, was, bat, to"
15382,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.129032258,"to, the, be, bat"
15383,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.129032258,"the, to, sars-cov-2, bat"
15384,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.129032258,"96.2%, the, sars-cov-2, bat"
15385,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.129032258,"the, to, sars-cov-2, was"
15386,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",Genetic evidence suggesting otherwise is yet to be presented.,0.129032258,"is, evidence, suggesting, to"
15387,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.129032258,"based, on, in, the, protein, a, from, pangolin"
15388,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.129032258,"to, be, an, and"
15389,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.129032258,"and, be, identity, to"
15390,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.129032258,"therefore, be, nucleotide, to"
15391,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.129032258,"that, sars-cov-2, to, identical"
15392,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.129032258,"are, nearly, viruses, from"
15393,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.129032258,"that, to, and, was"
15394,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.129032258,"genome, of, sars-cov-2, bat"
15395,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.129032258,"the, of, to, coronaviruses"
15396,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.129032258,"the, natural, of, sars-cov-2"
15397,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.129032258,"to, sars-cov-2, in, its"
15398,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.129032258,"was, also, in, the"
15399,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.129032258,"the, of, which, sars-cov-2"
15400,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.129032258,"among, associated, with, the, and, of, suggesting, to, that, in, this, sars-cov-2, more, be, than, by"
15401,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.129032258,"that, sars-cov-2, bats, or"
15402,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.129032258,"supporting, are, for, and"
15403,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.129032258,"that, the, of, were, in, to, a, market"
15404,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.129032258,"in, the, of, is, to, at, that, virus"
15405,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.129032258,"the, bats, is, very"
15406,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.129032258,"to, the, sars-cov-2, as"
15407,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.129032258,"closer, to, bat, sars-cov-2"
15408,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.129032258,"sars-cov-2, to, pangolin, cov"
15409,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.129032258,"the, of, that, sars-cov-2"
15410,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.129032258,"based, on, in, the, that, these, hosts, for"
15411,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.129032258,"this, suggests, the, sars-cov-2"
15412,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.129032258,"the, and, bat, that, in, ratg13, viruses, to"
15413,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.129032258,"the, that, are, sars-cov-2, all, bat, in, and"
15414,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.129032258,"sars-cov-2, and, bat, ratg13, pangolin, to, the, of"
15415,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.129032258,"the, that, sars-cov-2, bat"
15416,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.129032258,"the, sars-cov-2, has, bat"
15417,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.129032258,"the, origin, sars-cov-2, ratg13"
15418,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.129032258,"we, that, the, sars-cov-2"
15419,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.129032258,"this, that, the, of"
15420,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.129032258,"that, bats, or, sars-cov-2"
15421,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.129032258,"are, also, a, the, of, and, that, to"
15422,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.129032258,"a, sars-cov-2, and, pangolin"
15423,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.129032258,"cov, to, sars-cov-2, pangolin"
15424,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.129032258,"with, to, the, of"
15425,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.129032258,"sars-cov-2, of, the, and, with, to, virus, analysis"
15426,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.129032258,"the, from, analysis, and"
15427,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.129032258,"sars-cov-2, of, and, the"
15428,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.129032258,"that, the, and, of"
15429,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.129032258,"that, the, of, and"
15430,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.129032258,"sars-cov-2, is, and, the"
15431,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.129032258,"the, similarity, sars-cov-2, with"
15432,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.129032258,"sars-cov-2, to, identical, the"
15433,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.129032258,"the, sars-cov-2, in, and"
15434,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.129032258,"critical, the, are, in"
15435,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.129032258,"the, pangolin, of, and"
15436,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.129032258,"that, of, to, is, in, pangolin, sars-cov-2, the"
15437,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.129032258,"at, in, that, the, virus, is, to, of"
15438,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.129032258,"the, as, sars-cov-2, intermediate"
15439,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.129032258,"the, sars-cov-2, suggests, this"
15440,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.129032258,"in, the, that, was"
15441,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.129032258,"in, was, that, the"
15442,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.129032258,"that, to, be, sars-cov-2"
15443,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.129032258,"studies, to, that, very"
15444,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.129032258,"to, that, sars-cov-2, originated"
15445,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.129032258,"the, that, most, sars-cov-2"
15446,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.129032258,"the, of, host, and"
15447,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.129032258,"sars-cov-2, and, cov, the"
15448,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.129032258,"a, sars-cov-2, the, cov"
15449,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.129032258,"supporting, and, are, for"
15450,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.129032258,"sars-cov-2, may, in, a, of, that, with, for"
15451,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.129032258,"that, may, be, for, sars-cov-2, to, in, with"
15452,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.129032258,"the, has, identity, with"
15453,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.129032258,"the, which, has, in"
15454,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.129032258,"sars-cov-2, to, protein, in"
15455,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.129032258,"the, that, are, to, be, sars-cov-2, and, of"
15456,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.129032258,"similar, to, and, with, the, protein, of, sars-cov-2"
15457,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.129032258,"analysis, sars-cov-2, the, with, of, virus, and, to"
15458,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.129032258,"the, and, to, sars-cov-2, of, bat, ratg13, pangolin"
15459,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.128834356,"by, the, of, a, large, number, in, to, that, sars, with, civets, as, intermediate, and, however,, sars,, were, find, it, for"
15460,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.128834356,"as, a, of, the, civets, and, were, by, in, to, sars, it, with, large, number, however,, find, for, that, intermediate, sars,"
15461,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.128712871,"and, of, to, that, there, is, between, sars-cov-2, animal, more, likely, be, by"
15462,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.128712871,"there, is, between, and, more, likely, that, of, sars-cov-2, to, animal, be, by"
15463,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.128571429,"the, recombination, found, to, be, spike, which, of, and"
15464,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.128571429,"are, to, the, in, and, that, bats, be, for"
15465,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.128571429,"that, from, to, humans, a, coronavirus, in, with, the"
15466,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.128571429,"the, and, a, in, to, that, highly, coronaviruses, are"
15467,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.128571429,"the, of, from, found, in, this, evidence, humans, to"
15468,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.128571429,"of, cases, with, early, and, the, huanan, market, in"
15469,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.128571429,"a, of, but, and, the, from, animals, 2020,, including"
15470,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.128571429,"the, spike, and, which, to, be, of, found, recombination"
15471,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.128571429,"the, and, to, that, sars-cov-2, is, of, sarbecovirus, bat"
15472,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.128571429,"in, found, to, closely, related, that, the, of, sars-cov-2"
15473,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.128571429,"in, the, a, coronavirus, that, from, to, humans, with"
15474,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.128571429,"to, the, have, been, in, and, suggesting, that, these"
15475,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.128571429,"and, to, possibility, was, the, of, that, a, laboratory"
15476,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.128571429,"a, of, in, the, or, to, virus, closely, related"
15477,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.128571429,"on, the, and, of, to, huanan, taken, from, market"
15478,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.128571429,"the, of, or, to, a, closely, related, virus, in"
15479,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.128571429,"the, to, humans, from, evidence, in, of, this, found"
15480,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.128571429,"found, that, the, of, to, as, an, intermediate, host"
15481,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.128571429,"at, an, bat, to, a, as, from, in, for, the, virus, by, sars, live, of, and, also, including"
15482,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.128571429,"from, the, also, for, to, a, live, virus, bat, as, and, by, sars, in, of, at, an, including"
15483,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.128571429,"the, of, with, and, early, cases, huanan, market, in"
15484,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.128571429,"the, taken, from, huanan, market, and, to, of, on"
15485,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.128571429,"sars-cov-2, of, natural, on, the, to, binding, ace2, protein"
15486,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.128571429,"the, rbd, in, to, ace2, (fig., that, coronaviruses, of"
15487,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.128571429,"been, in, the, and, to, suggesting, that, these, have"
15488,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.128571429,"2020,, the, but, including, from, and, a, of, animals"
15489,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.128571429,"that, the, of, a, laboratory, was, and, to, possibility"
15490,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.128571429,"bats, are, for, the, and, be, in, that, to"
15491,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.128571429,"the, sars-cov-2, and, of, sarbecovirus, is, to, that, bat"
15492,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.128571429,"found, in, the, of, that, sars-cov-2, closely, related, to"
15493,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.128571429,"in, the, a, highly, that, coronaviruses, are, to, and"
15494,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.128571429,"coronaviruses, to, in, the, rbd, (fig., that, ace2, of"
15495,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.128571429,"the, of, as, an, intermediate, host, found, that, to"
15496,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.128571429,"the, binding, of, sars-cov-2, protein, to, ace2, natural, on"
15497,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.128205128,"genetic, sars-cov-2, other, coronaviruses, to"
15498,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.128205128,"viruses, are, two, the, from"
15499,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.128205128,"in, bats, the, as, horseshoe"
15500,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.128205128,"the, bats, and, to, of"
15501,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.128205128,"more, than, of, to, and"
15502,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.128205128,"of, to, which, many, and"
15503,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.128205128,"in, bats, more, sars-cov-2, than"
15504,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.128205128,"the, genetic, to, sars-cov, and"
15505,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.128205128,"its, in, sars-cov-2, to, virus"
15506,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.128205128,"is, identical, to, its, in"
15507,"Bats have been reported as being the rich source of 

coronaviruses","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.128205128,"have, been, the, of, coronaviruses"
15508,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.128205128,"that, sars-cov-2, is, a, shares"
15509,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.128205128,"virus, a, that, with, and"
15510,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.128205128,"a, virus, that, with, sars-cov-2"
15511,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.128205128,"that, sars-cov-2, with, virus, and"
15512,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.128205128,"research, the, identified, with, sars-cov-2"
15513,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.128205128,"sars-cov-2, shares, is, a, that"
15514,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.128205128,"that, the, a, of, sars-cov"
15515,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.128205128,"the, to, bat, and, human"
15516,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.128205128,"the, virus, to, identity, human"
15517,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.128205128,"the, with, bat, and, to"
15518,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.128205128,"known, to, of, with, sars-cov-2"
15519,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.128205128,"the, of, to, bat, is"
15520,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.128205128,"of, similar, to, are, sars-cov-2"
15521,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.128205128,"the, animal, reservoirs, of, and"
15522,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.128205128,"the, that, as, a, of"
15523,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.128205128,"a, of, has, that, the"
15524,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.128205128,"that, bats, the, a, of"
15525,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.128205128,"the, most, known, viruses, as"
15526,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.128205128,"the, of, that, in, a, use, receptor, cells, and, to"
15527,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.128205128,"can, be, a, virus, to, bats, of, and, are, as"
15528,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.128205128,"is, a, and, the, in"
15529,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.128205128,"that, is, in, a, to"
15530,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.128205128,"was, to, bats,, the, in"
15531,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.128205128,"in, the, bats,, and, a"
15532,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.128205128,"the, that, is, in, of"
15533,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.128205128,"infected, in, the, wet, market"
15534,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.128205128,"is, that, the, infected, animal"
15535,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.128205128,"were, to, in, and, china"
15536,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.128205128,"the, of, sars-cov-2, to, a"
15537,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.128205128,"the, of, early, at, outbreak"
15538,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.128205128,"of, sars-cov-2, the, genomic, through"
15539,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.128205128,"t, is, the, to, bat-cov"
15540,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",Bats are likely reservoir hosts for SARS-CoV-2,0.128205128,"bats, hosts, for, are, sars-cov-2"
15541,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.128205128,"the, is, to, coronavirus, from"
15542,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.128205128,"the, sars-cov-2, to, a, with"
15543,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.128205128,"species, of, to, and, the"
15544,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.128205128,"of, the, to, which, and"
15545,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.128205128,"other, to, and, the, of"
15546,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.128205128,"the, of, that, in, is"
15547,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.128205128,"the, sars-cov-2, in, of, is"
15548,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.128205128,"that, the, to, and, sars-cov-2"
15549,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.128205128,"and, that, of, the, is"
15550,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.128205128,"is, the, bat, to, of"
15551,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.128205128,"of, the, evidence, yet, identified"
15552,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.128205128,"is, sars-cov-2, the, humans, from"
15553,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.128205128,"the, of, sars-cov-2, from, pangolins"
15554,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.128205128,"is, from, in, the, of"
15555,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.128205128,"evidence, in, the, of, sars-cov-2"
15556,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.128205128,"that, the, in, a, and"
15557,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.128205128,"and, the, that, originated, in"
15558,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.128205128,"a, virus, the, was, by"
15559,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.128205128,"in, a, to, have, are, likely, transmitted, from, found, as"
15560,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.128205128,"and, host, species, from, a, found, in, likely, as, to"
15561,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.128205128,"from, reservoir, as, and, to, sars-cov-2, have, been, in, a"
15562,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.128205128,"the, as, a, that, to"
15563,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.128205128,"that, the, of, to, sars-cov-2"
15564,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.128205128,"to, of, from, a, sars-cov-2"
15565,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.128205128,"the, of, to, that, as"
15566,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.128205128,"that, sars-cov-2, from, a, to"
15567,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.128205128,"studies, the, genome, and, that"
15568,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.128205128,"has, that, sars-cov-2, the, and"
15569,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.128205128,"the, sars-cov-2, genome, that, and"
15570,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.128205128,"of, the, have, that, was"
15571,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.128205128,"suggest, that, the, bat, ratg13"
15572,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.128205128,"the, two, are, from, viruses"
15573,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.128205128,"that, a, bat, of, sars-cov-2"
15574,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.128205128,"the, sars-cov-2, this, bat, of"
15575,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.128205128,"that, the, of, sars-cov-2, and, at, two, both, which, a"
15576,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.128205128,"the, sars-cov-2, at, huanan, market"
15577,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.128205128,"that, the, of, sars-cov-2, to"
15578,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.128205128,"to, 2019,, and, the, sars-cov-2"
15579,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.128205128,"a, the, to, that, in"
15580,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.128205128,"show, that, a, to, in"
15581,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.128205128,"a, is, the, in, and"
15582,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.128205128,"the, with, at, of, and"
15583,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.128205128,"a, the, virus, was, by"
15584,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.128205128,"the, at, huanan, market, was"
15585,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.128205128,"he, of, the, from, a"
15586,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.128205128,"the, animal, than, in, reservoirs"
15587,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.128205128,"the, were, more, to, in"
15588,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.128205128,"at, the, huanan, market, was"
15589,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.128205128,"in, the, animal, reservoirs, than"
15590,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.128205128,"and, the, was, market, in"
15591,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.128205128,"the, likely, that, in, and"
15592,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.128205128,"the, identified, evidence, of, yet"
15593,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.128205128,"and, to, of, more, than"
15594,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.128205128,"the, of, covid-19, were, huanan"
15595,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.128205128,"evidence, that, the, as, a"
15596,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.128205128,"have, transmitted, from, to, a, are, as, likely, found, in"
15597,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.128205128,"a, is, to, that, in"
15598,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.128205128,"from, an, animal, in, to"
15599,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.128205128,"to, covid-19, a, from, is"
15600,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.128205128,"the, live, animals, to, in, a, of, “the, emergence, was, that, were, by, other, market"
15601,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.128205128,"with, and, a, virus, that"
15602,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.128205128,"with, the, and, to, bat"
15603,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.128205128,"to, the, that, as, a"
15604,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.128205128,"a, the, with, that, and"
15605,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.128205128,"and, bat, similarity, to, the"
15606,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.128205128,"that, the, virus, and, seafood"
15607,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.128205128,"that, the, and, this, from"
15608,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.128205128,"the, was, in, of, horseshoe"
15609,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.128205128,"the, of, horseshoe, in, and"
15610,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.128205128,"studies, that, and, the, genome"
15611,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.128205128,"to, the, a, high, bat"
15612,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.128205128,"to, and, genome, was, the"
15613,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.128205128,"the, to, that, bat, and"
15614,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.128205128,"that, a, bat, to, first"
15615,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.128205128,"to, the, coronavirus, from, is"
15616,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.128205128,"from, to, the, of, virus"
15617,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.128205128,"be, the, sars-cov-2, and, intermediate"
15618,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Bats have been reported as being the rich source of 

coronaviruses",0.128205128,"the, of, have, been, coronaviruses"
15619,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.128205128,"sars-cov-2, a, with, to, the"
15620,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.128205128,"similarity, sars-cov-2, pangolin, to, the"
15621,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.128205128,"of, the, sars-cov-2, similar, to"
15622,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.128205128,"the, with, similar, to, of"
15623,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.128205128,"isolated, from, with, sars-cov-2, the"
15624,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.128205128,"that, sars-cov-2, has, and, the"
15625,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.128205128,"a, of, virus, by, the"
15626,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.128205128,"the, genetic, of, to, and"
15627,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.128205128,"data, that, sars-cov-2, a, to"
15628,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.128205128,"the, to, virus, in, and"
15629,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.128205128,"the, are, in, from, a"
15630,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.128205128,"the, from, to, humans,, and"
15631,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.128205128,"virus, to, the, and, was"
15632,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.128205128,"virus, that, from, to, a"
15633,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.128205128,"from, a, virus, that, in"
15634,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.128205128,"that, the, of, most, covid-19"
15635,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.128205128,"that, the, was, at, of"
15636,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.128205128,"evidence, the, that, a, as"
15637,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.128205128,"the, is, of, a, virus"
15638,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.128205128,"the, is, of, evidence, a"
15639,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.128205128,"that, the, of, evidence, is"
15640,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.128205128,"were, in, more, to, the"
15641,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.128205128,"and, the, virus, to, in"
15642,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.128205128,"virus, that, to, the, and"
15643,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.128205128,"virus, the, to, and, that"
15644,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.128205128,"the, in, origin, is, and"
15645,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.128205128,"to, that, the, virus, origin"
15646,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.128205128,"seafood, in, the, was, outbreak"
15647,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.128205128,"cov, and, sars-like, together, with"
15648,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.128205128,"the, and, of, that, to"
15649,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.128205128,"zoonotic, and, the, that, to"
15650,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.128205128,"the, of, that, is, virus"
15651,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.128205128,"the, infected, wet, market, in"
15652,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.128205128,"in, were, reported, and, the"
15653,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.128205128,"seafood, in, the, outbreak, was"
15654,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.128205128,"the, in, that, was, virus"
15655,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.128205128,"the, to, sars-cov-2, of, bat"
15656,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.128205128,"the, sars-cov-2, to, bat, coronavirus"
15657,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.128205128,"several, have, sars-cov-2, to, that"
15658,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.128205128,"he, of, a, the, from"
15659,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.128205128,"are, the, from, a, in"
15660,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.128205128,"that, virus, to, from, a"
15661,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.128205128,"is, that, to, an, animal"
15662,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.128205128,"the, to, humans, from, is"
15663,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.128205128,"to, humans, from, the, sars-cov-2"
15664,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.128205128,"the, bats, to, sars-cov-2, bat"
15665,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.128205128,"the, closely, related, to, bat"
15666,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.128205128,"the, of, to, in, is"
15667,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.128205128,"in, from, an, animal, to"
15668,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.128205128,"in, the, from, and, amplified"
15669,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.128205128,"is, that, a, and, has"
15670,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.128205128,"is, natural, sars-cov-2, or, a"
15671,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.128205128,"has, that, and, sars-cov-2, a"
15672,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.128205128,"the, infected, that, animal, is"
15673,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.128205128,"the, sars-cov-2, humans, from, is"
15674,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.128205128,"the, from, that, sars-cov-2, and"
15675,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.128205128,"that, is, an, animal, to"
15676,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.128205128,"of, sars-cov-2, animal, and, humans"
15677,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.128205128,"is, to, be, likely, intermediate"
15678,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.128205128,"and, that, the, coronavirus, of"
15679,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.128205128,"to, virus, that, and, the"
15680,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.128205128,"to, that, the, of, and"
15681,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.128205128,"the, virus, to, of, from"
15682,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.128205128,"the, of, from, with, genome"
15683,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.128205128,"the, covid-19, of, to, virus"
15684,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.128205128,"the, of, to, with, genome"
15685,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.128205128,"the, reservoir, with, to, of"
15686,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.128205128,"similar, to, the, of, sars-cov-2"
15687,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.128205128,"that, the, of, sars-cov-2, coronavirus"
15688,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.128205128,"has, the, with, of, and"
15689,"the close relation  

between SARS coronavirus and 2019-nCoV","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.128205128,"the, close, sars, coronavirus, and"
15690,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.128205128,"the, and, to, bat, of"
15691,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.128205128,"that, the, between, and, bat"
15692,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","the close relation  

between SARS coronavirus and 2019-nCoV",0.128205128,"the, coronavirus, close, and, sars"
15693,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.128205128,"and, hubei, wuhan, at, seafood, market, in, on, a, was"
15694,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.128205128,"market, wuhan, that, in, identified, were, exposed, and, who, a"
15695,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.128205128,"the, that, are, to, of"
15696,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.128205128,"the, amino, acid, of, that"
15697,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.128205128,"that, are, the, of, sars-cov"
15698,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.128205128,"that, virus, in, from, a"
15699,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.128205128,"virus, from, in, is, sars-cov-2"
15700,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.128205128,"the, a, that, with, and"
15701,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.128205128,"a, that, with, the, sars-cov-2"
15702,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.128205128,"and, are, of, the, other"
15703,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.128205128,"humans, and, of, sars-cov-2, animal"
15704,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.128205128,"a, of, the, that, sars-cov-2, and, at, two, which, both"
15705,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.128205128,"is, likely, to, intermediate, be"
15706,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.128205128,"research, identified, sars-cov-2, with, the"
15707,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.128205128,"a, from, china, identified, sars-cov-2"
15708,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.128205128,"that, has, a, and, is"
15709,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.128205128,"similar, to, with, the, of"
15710,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.128205128,"that, the, a, in, to"
15711,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.128205128,"that, the, in, to, of"
15712,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.128205128,"to, the, of, a, with"
15713,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.128205128,"in, the, of, horseshoe, was"
15714,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.128205128,"that, the, be, origin, of"
15715,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.128205128,"be, zoonosis, the, that, animal"
15716,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.128205128,"the, sars-cov-2, from, pangolins, of"
15717,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.128205128,"the, sars-cov-2, from, of, a"
15718,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.128205128,"between, and, pangolins, the, from"
15719,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.128205128,"the, from, sars-cov-2, a, and"
15720,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.128205128,"virus, to, sars-cov-2, in, its"
15721,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.128205128,"the, in, of, a, bat"
15722,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.128205128,"the, to, bat, a, high"
15723,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.128205128,"bat, high, to, the, of"
15724,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.128205128,"the, sars-cov-2, is, to, of"
15725,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.128205128,"the, and, sars-cov-2, to, genome"
15726,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.128205128,"2019,, the, to, sars-cov-2, and"
15727,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.128205128,"the, genome, to, and, was"
15728,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.128205128,"the, not, to, that, in"
15729,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.128205128,"in, the, that, sars-cov-2, research"
15730,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.128205128,"from, with, genome, the, of"
15731,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.128205128,"the, of, sars-cov-2, with, coronaviruses"
15732,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.128205128,"a, bat, that, of, sars-cov-2"
15733,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.128205128,"in, of, that, sars-cov-2, virus"
15734,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.128205128,"of, a, that, virus, bat"
15735,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.128205128,"virus, the, to, identity, human"
15736,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.128205128,"the, of, origin, has, a"
15737,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.128205128,"and, the, of, shows, that"
15738,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.128205128,"the, of, sars-cov-2, to, in"
15739,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.128205128,"sars-cov-2, to, in, the, ratg13"
15740,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.128205128,"the, of, sars-cov-2, to, ratg13"
15741,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.128205128,"the, of, sars-cov-2, has, in"
15742,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.128205128,"the, and, in, were, reported"
15743,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.128205128,"sars-cov-2, and, in, an, humans"
15744,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.128205128,"the, rbd, sars-cov-2, homology, with"
15745,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.128205128,"the, rbd, homology, with, sars-cov-2"
15746,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.128205128,"the, sars-cov-2, that, and, to"
15747,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.128205128,"sars-cov-2, a, and, was, in"
15748,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.128205128,"the, to, known, in, covid-19"
15749,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.128205128,"the, were, to, animal, in"
15750,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.128205128,"at, the, early, of, outbreak"
15751,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.128205128,"from, samples, at, the, market, in, early, of, 2020, was"
15752,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.128205128,"this, that, in, the, of"
15753,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.128205128,"that, the, sars-cov-2, in, samples"
15754,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.128205128,"the, of, that, sars-cov-2, from"
15755,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.128205128,"is, the, virus, of, a"
15756,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.128205128,"sars-cov-2, a, natural, is, or"
15757,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.128205128,"a, the, covid-19, is, of"
15758,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.128205128,"in, the, of, horseshoe, and"
15759,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.128205128,"the, of, and, animal, reservoirs"
15760,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.128205128,"sars-cov-2, to, bat, bats, the"
15761,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.128205128,"the, to, bat, and, that"
15762,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.128205128,"that, are, the, including, and"
15763,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.128205128,"in, that, the, and, bat"
15764,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.128205128,"the, were, in, to, and"
15765,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.128205128,"and, to, the, viruses, in"
15766,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.128205128,"in, china, the, virus, and"
15767,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.128205128,"the, of, to, bat, sars-related"
15768,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.128205128,"the, in, and, to, of"
15769,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.128205128,"an, species, and, in, the"
15770,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.128205128,"with, known, sars-cov-2, to, of"
15771,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.128205128,"to, sars-cov-2, a, of, from"
15772,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.128205128,"of, sars-cov-2, from, closest, relatives"
15773,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.128205128,"is, the, related, to, sars-cov-2"
15774,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.128205128,"the, of, to, sars-cov-2, also"
15775,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.128205128,"also, the, similarity, sars-cov-2, viruses"
15776,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.128205128,"are, to, that, the, of"
15777,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.128205128,"of, that, the, to, and"
15778,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.128205128,"is, the, to, rbd, of"
15779,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.128205128,"that, the, to, through, of"
15780,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.128205128,"that, the, with, of, to"
15781,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.128205128,"to, the, of, rbd, with"
15782,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.128205128,"the, from, in, of, is"
15783,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.128205128,"to, closely, related, bat, the"
15784,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.128205128,"bat, to, the, of, sars-related"
15785,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.128205128,"the, is, by, bat, viruses,"
15786,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.128205128,"the, to, in, is, covid-19"
15787,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.128205128,"the, known, covid-19, in, to"
15788,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.128205128,"in, and, be, humans, through"
15789,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.128205128,"humans, is, and, be, the"
15790,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.128205128,"in, the, case, first, and"
15791,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.128205128,"from, host, to, a, as, likely, and, found, in, species"
15792,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.128205128,"that, the, of, market, in, emergence, was, to, “the, live, animals, were, a, by, other"
15793,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.128205128,"was, and, in, at, a, seafood, market, wuhan, hubei, on"
15794,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.128205128,"the, of, in, samples, from, market, early, 2020, was, at"
15795,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.128205128,"that, and, identified, in, who, were, exposed, a, market, wuhan"
15796,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.128205128,"is, evidence, the, of, a"
15797,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.128205128,"this, a, that, the, and"
15798,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.128205128,"a, the, to, with, sars-cov-2"
15799,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.128205128,"to, humans, is, contact, the"
15800,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.128205128,"a, the, to, in, and"
15801,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.128205128,"in, an, sars-cov-2, and, humans"
15802,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.128205128,"a, was, and, in, sars-cov-2"
15803,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.128205128,"a, that, sars-cov-2, the, virus"
15804,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.128205128,"a, the, sars-cov-2, with, that"
15805,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.128205128,"samples, the, that, in, sars-cov-2"
15806,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.128205128,"a, that, sars-cov-2, laboratory, or"
15807,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.128205128,"a, it, that, sars-cov-2, is"
15808,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.128205128,"the, is, to, bat, of"
15809,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.128205128,"to, the, that, as, of"
15810,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.128205128,"bat, similarity, to, the, of"
15811,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.128205128,"is, identical, to, in, its"
15812,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.128205128,"of, the, shows, that, and"
15813,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.128205128,"that, natural, and, the, of"
15814,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.128205128,"sars-cov-2, the, of, through, genomic"
15815,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.128205128,"that, virus, in, of, sars-cov-2"
15816,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.128205128,"the, of, covid-19, that, most"
15817,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.128205128,"a, the, of, and, in, that, to, use, receptor, cells"
15818,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.128205128,"the, and, genetic, to, sars-cov"
15819,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.128205128,"of, genetic, to, the, and"
15820,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.128205128,"in, the, both, cov, and"
15821,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.128205128,"and, the, from, to, humans,"
15822,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.128205128,"the, amino, acid, that, of"
15823,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.128205128,"that, the, seafood, and, virus"
15824,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.128205128,"in, the, that, to, of"
15825,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.128205128,"in, to, that, of, the"
15826,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.128205128,"in, humans, through, be, and"
15827,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.128205128,"that, have, the, was, of"
15828,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.128205128,"the, of, that, been, in"
15829,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.128205128,"that, the, virus, was, it"
15830,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.128205128,"and, the, virus, was, to"
15831,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.128205128,"that, probably, the, same, with"
15832,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.128205128,"of, the, covid-19, were, huanan"
15833,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.128205128,"of, the, two, in, with"
15834,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.128205128,"the, that, not, in, to"
15835,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.128205128,"the, as, in, horseshoe, bats"
15836,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.128205128,"the, viruses,, by, is, bat"
15837,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.128205128,"species, in, all, by, the"
15838,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.128205128,"bat, by, the, in, china"
15839,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.128205128,"humans, is, the, be, and"
15840,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.128205128,"is, humans, contact, to, the"
15841,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.128205128,"is, and, to, the, between"
15842,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.128205128,"and, species, an, in, the"
15843,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.128205128,"the, by, all, species, in"
15844,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.128205128,"bats, are, a, as, of, virus, can, and, be, to"
15845,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.128205128,"in, the, case, and, first"
15846,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.128205128,"the, isolated, from, with, sars-cov-2"
15847,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.128205128,"sars-cov-2, from, virus, is, in"
15848,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.128205128,"the, between, from, pangolins, and"
15849,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.128205128,"the, is, that, of, and"
15850,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.128205128,"is, a, that, and, the"
15851,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.128205128,"the, covid-19, is, of, a"
15852,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.128205128,"a, and, this, the, that"
15853,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.128205128,"is, covid-19, from, a, to"
15854,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.128205128,"also, to, which, the, animals"
15855,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.128205128,"the, also, likely, for, covid-19"
15856,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.128205128,"that, sars-cov-2, has, a, and"
15857,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.128205128,"bat, overall, genome, with, sars-cov-2"
15858,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.128205128,"natural, of, sars-, cov-2, origin"
15859,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.128205128,"to, that, sars-cov-2, a, from"
15860,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.128205128,"in, a, show, that, to"
15861,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.128205128,"first, to, bat, that, a"
15862,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.128205128,"a, data, to, that, sars-cov-2"
15863,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.128205128,"in, it, that, an, bat"
15864,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.128205128,"that, a, of, sars-cov-2, the"
15865,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.128205128,"that, sars-cov-2, a, the, of"
15866,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.128205128,"sars-cov-2, have, been, from, reservoir, to, a, as, and, in"
15867,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.128205128,"the, of, has, origin, a"
15868,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.128205128,"and, that, sars-cov-2, was, to"
15869,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.128205128,"to, and, that, viruses, ratg13"
15870,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.128205128,"genome, overall, with, bat, sars-cov-2"
15871,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.128205128,"the, most, known, as, viruses"
15872,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.128205128,"sars-cov-2, to, coronaviruses, genetic, other"
15873,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.128205128,"the, of, coronaviruses, with, sars-cov-2"
15874,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.128205128,"the, of, natural, sars-cov-2, to"
15875,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.128205128,"to, natural, the, of, be"
15876,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.128205128,"the, natural, with, to, of"
15877,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.128205128,"closest, relatives, of, from, sars-cov-2"
15878,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.128205128,"was, the, of, sars-cov-2, to"
15879,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.128205128,"the, to, in, bats,, was"
15880,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.128205128,"the, to, which, animals, also"
15881,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.128205128,"is, evidence, that, the, of"
15882,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.128205128,"natural, origin, of, sars-, cov-2"
15883,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.128205128,"the, of, to, be, natural"
15884,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.128205128,"the, sars-cov-2, to, coronavirus, bat"
15885,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.128205128,"the, sars-cov-2, a, from, and"
15886,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.128205128,"the, covid-19, for, also, likely"
15887,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.128205128,"a, that, the, to, sars-cov-2"
15888,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.128205128,"a, that, the, to, bat"
15889,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.128205128,"that, hosts, for, sars-cov-2, are"
15890,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.128205128,"and, to, of, many, which"
15891,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.128205128,"that, a, bat, virus, of"
15892,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.128205128,"that, the, to, a, bat"
15893,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.128205128,"the, by, bat, in, china"
15894,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.128205128,"that, are, hosts, for, sars-cov-2"
15895,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.128205128,"the, pangolin, intermediate, for, sars-cov-2"
15896,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.128205128,"the, two, of, with, in"
15897,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.128205128,"the, sars-cov-2, sequences, and, of"
15898,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.128205128,"that, in, and, the, of"
15899,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.128205128,"that, from, the, and, this"
15900,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.128205128,"of, the, that, sars-cov-2, coronavirus"
15901,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.128205128,"sars-cov-2, and, bats, the, of"
15902,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.128205128,"that, sars-cov-2, similarity, to, and"
15903,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.128205128,"the, in, that, bat, sars-cov-2."
15904,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.128205128,"the, ratg13, to, sars-cov-2, in"
15905,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.128205128,"sars-cov-2, in, bats, more, than"
15906,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.128205128,"this, that, in, the, for"
15907,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.128205128,"the, sars-cov-2, and, bat, pangolin"
15908,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.128205128,"the, that, same, with, probably"
15909,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.128205128,"bat, the, of, sars-cov-2, this"
15910,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.128205128,"of, the, and, sars-cov-2, sequences"
15911,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.128205128,"the, viruses, also, sars-cov-2, similarity"
15912,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.128205128,"the, virus, and, in, china"
15913,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.128205128,"the, in, those, bat, origin"
15914,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.128205128,"other, the, to, of, and"
15915,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.128205128,"that, pangolin, and, the, of"
15916,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.128205128,"to, the, with, a, sars-cov-2"
15917,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.128205128,"the, of, ratg13, to, sars-cov-2"
15918,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.128205128,"similarity, sars-cov-2, and, to, that"
15919,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.128205128,"the, sars-cov-2, to, of, is"
15920,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.128205128,"the, of, pangolin-cov, is, sars-cov-2"
15921,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.128205128,"the, of, pangolin-cov, by, with"
15922,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.128205128,"the, sars-cov-2, evidence, in, of"
15923,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.128205128,"a, the, in, bats,, and"
15924,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.128205128,"the, from, in, and, amplified"
15925,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.128205128,"the, and, cov, both, in"
15926,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.128205128,"that, the, of, a, sars-cov"
15927,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.128205128,"the, of, that, a, bats"
15928,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.128205128,"the, are, that, of, sars-cov"
15929,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.128205128,"the, that, are, and, including"
15930,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.128205128,"together, with, sars-like, cov, and"
15931,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.128205128,"in, to, the, sars-cov-2, and"
15932,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.128205128,"the, of, in, that, this"
15933,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.128205128,"and, the, of, that, natural"
15934,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.128205128,"of, that, the, virus, and"
15935,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.128205128,"of, the, in, and, that"
15936,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.128205128,"this, the, in, that, for"
15937,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.128205128,"sars-cov-2, with, and, virus, that"
15938,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.128205128,"with, and, of, at, the"
15939,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.128205128,"and, that, the, of, bat"
15940,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.128205128,"the, that, bat, in, and"
15941,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.128205128,"the, of, bat, it, that"
15942,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.128205128,"that, bat, it, in, an"
15943,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.128205128,"sars-cov-2, identity, to, the, of"
15944,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.128205128,"the, of, sars-cov-2, is, pangolin-cov"
15945,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.128205128,"pangolin, the, intermediate, for, sars-cov-2"
15946,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.128205128,"the, virus, to, that, origin"
15947,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.128205128,"a, the, with, to, of"
15948,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.128205128,"the, rbd, of, with, to"
15949,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.128205128,"the, of, with, by, pangolin-cov"
15950,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.128205128,"sars-cov-2., bat, the, that, in"
15951,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.128205128,"in, the, bat, origin, those"
15952,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.128205128,"sars-cov-2, the, that, of, is"
15953,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.128205128,"sars-cov-2, be, and, the, intermediate"
15954,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.128205128,"sars-cov-2, and, cov, the, between"
15955,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.128205128,"has, the, of, sars-cov-2, in"
15956,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.128205128,"of, the, been, in, that"
15957,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.128205128,"the, that, animal, be, zoonosis"
15958,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.128205128,"the, that, in, research, sars-cov-2"
15959,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.128205128,"that, sars-cov-2, a, laboratory, or"
15960,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.128205128,"with, to, the, reservoir, of"
15961,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.128205128,"the, of, with, to, natural"
15962,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.128205128,"that, sars-cov-2, the, of, to"
15963,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.128205128,"the, of, to, rbd, is"
15964,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.128205128,"viruses, that, to, ratg13, and"
15965,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.128205128,"the, bat, and, similarity, to"
15966,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.128205128,"to, the, of, high, bat"
15967,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.128205128,"the, similarity, of, to, bat"
15968,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.128205128,"the, of, identity, to, and"
15969,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.128205128,"the, of, identity, to, sars-cov-2"
15970,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.127906977,"viruses, less, closely, related, to, and, a, the, which, is, where"
15971,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.127906977,"and, the, to, where, viruses, a, closely, related, which, is, less"
15972,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.127906977,"out, of, with, a, to, and, the, were, only, in, earliest"
15973,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.127906977,"the, of, and, were, a, only, in, earliest, with, out, to"
15974,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.127819549,"in, the, of, a, to, as, taken, with, found, were, and, that, likely, sars, from, this, species"
15975,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.127819549,"the, of, and, were, species, that, from, a, found, in, sars, taken, this, likely, with, as, to"
15976,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.127659574,"related, bat, to, genetic, which, sars-cov-2"
15977,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.127659574,"and, human, natural, of, the, virus"
15978,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.127659574,"are, viruses, the, in, bats, or"
15979,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.127659574,"are, to, of, the, bats, and"
15980,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.127659574,"of, the, and, with, bat, human"
15981,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.127659574,"have, the, of, with, to, human"
15982,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.127659574,"is, the, was, as, of, a"
15983,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.127659574,"the, sequence, a, from, sars-cov-2, is"
15984,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.127659574,"the, that, all, to, bat, and"
15985,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.127659574,"with, the, as, natural, host, genome"
15986,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.127659574,"virus, has, genome, of, and, bat"
15987,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.127659574,"a, the, natural, reservoir, of, and"
15988,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.127659574,"that, the, was, to, and, sars-cov-2"
15989,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.127659574,"that, the, virus, to, bat, and"
15990,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.127659574,"sars-cov-2, the, and, in, of, is"
15991,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.127659574,"the, to, that, sars-cov-2, and, including"
15992,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.127659574,"a, its, in, the, that, human"
15993,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.127659574,"the, bats, most, as, of, and"
15994,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.127659574,"the, of, sars-cov-2, to, for, humans"
15995,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.127659574,"were, zoonotic, of, in, to, on"
15996,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.127659574,"the, is, it, to, number, of"
15997,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.127659574,"a, of, the, is, to, sars-cov-2"
15998,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.127659574,"the, animals, that, to, and, transmission"
15999,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.127659574,"a, the, is, to, with, sars-cov-2"
16000,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.127659574,"is, sars-cov-2, from, a, the, sequence"
16001,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.127659574,"the, is, to, sars-cov-2, with, a"
16002,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.127659574,"a, due, to, with, sars-cov-2, the"
16003,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.127659574,"in, the, was, from, animals, humans"
16004,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.127659574,"the, is, that, of, lineage, in"
16005,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.127659574,"to, the, whole, genome, and, that"
16006,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.127659574,"the, was, in, humans, from, animals"
16007,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.127659574,"a, coronavirus, from, the, to, with"
16008,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.127659574,"of, sars-cov-2, humans, from, in, to"
16009,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.127659574,"evidence, the, in, to, from, humans"
16010,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.127659574,"the, has, is, to, of, from"
16011,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.127659574,"the, is, to, of, has, been"
16012,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.127659574,"identified, has, been, to, with, sars-cov-2"
16013,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.127659574,"sars-cov-2, as, a, between, from, and"
16014,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.127659574,"the, a, spillover, as, to, of"
16015,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.127659574,"hypothesis, to, origin, the, that, from"
16016,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.127659574,"a, of, sars-cov-2, to, origin, that"
16017,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.127659574,"have, the, sars-cov-2, and, genome, that"
16018,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.127659574,"the, from, that, bat, and, coronavirus"
16019,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.127659574,"to, this, that, sars-cov-2, the, of"
16020,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.127659574,"the, humans, from, animals, at, market"
16021,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.127659574,"the, from, at, huanan, market, of"
16022,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.127659574,"animals, that, transmission, to, and, the"
16023,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.127659574,"in, the, with, that, of, at"
16024,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.127659574,"sars-cov-2, and, the, lineage, b, of"
16025,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.127659574,"of, the, in, with, 2019, and"
16026,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.127659574,"a, and, with, the, of, in"
16027,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.127659574,"and, in, the, of, origin, is"
16028,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.127659574,"the, virus, from, at, a, market"
16029,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.127659574,"he, virus, from, at, the, of"
16030,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.127659574,"the, of, and, coronavirus, been, from"
16031,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.127659574,"the, more, than, to, human, animal"
16032,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.127659574,"to, in, human, these, were, animal"
16033,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.127659574,"the, and, that, sars-cov-2, animal, was"
16034,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.127659574,"that, the, in, and, at, market"
16035,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.127659574,"the, was, at, huanan, market, and"
16036,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.127659574,"on, of, were, to, in, zoonotic"
16037,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.127659574,"sars-cov-2, to, humans, from, in, of"
16038,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.127659574,"to, the, in, zoonotic, and, of"
16039,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.127659574,"the, covid-19, was, to, and, that"
16040,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.127659574,"the, earliest, cases, that, were, market,"
16041,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.127659574,"the, was, to, market,, that, of"
16042,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.127659574,"a, from, the, to, have, sars-cov-2"
16043,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.127659574,"the, earliest, cases, were, market,, that"
16044,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.127659574,"cases, could, be, the, market,, that"
16045,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.127659574,"that, could, be, sars-cov-2, animals, with"
16046,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.127659574,"the, to, humans, from, evidence, in"
16047,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.127659574,"genome, a, sequence, and, the, bat"
16048,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.127659574,"studies, the, to, a, high, and"
16049,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.127659574,"that, the, in, and, to, of"
16050,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.127659574,"that, the, with, of, and, to"
16051,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.127659574,"the, has, to, from, of, is"
16052,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.127659574,"the, from, that, to, and, coronavirus"
16053,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.127659574,"the, to, sars-cov-2, was, from, a"
16054,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.127659574,"virus, genome, and, bat, has, of"
16055,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.127659574,"the, a, coronavirus, from, to, with"
16056,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.127659574,"sars-cov-2, with, has, been, identified, to"
16057,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.127659574,"from, the, a, sars-cov-2, have, to"
16058,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.127659574,"identified, the, a, coronavirus, from, pangolin"
16059,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.127659574,"a, the, has, been, have, to"
16060,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.127659574,"sars-cov-2, humans, with, infected, to, the"
16061,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.127659574,"to, the, that, has, by, and"
16062,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.127659574,"the, sars-cov-2, animal, was, that, and"
16063,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.127659574,"the, that, animal, of, is, by"
16064,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.127659574,"the, analysis, that, to, which, and"
16065,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.127659574,"that, the, sars-cov-2, based, on, studies"
16066,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.127659574,"the, bats, a, its, from, and"
16067,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.127659574,"a, virus, at, the, market, from"
16068,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.127659574,"the, at, market, that, in, and"
16069,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.127659574,"bats, of, and, are, to, the"
16070,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.127659574,"was, and, to, bats, the, of"
16071,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.127659574,"as, a, of, the, was, is"
16072,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.127659574,"was, that, the, as, a, of"
16073,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.127659574,"the, of, virus, is, that, a"
16074,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.127659574,"humans, and, more, likely, that, to"
16075,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.127659574,"the, natural, reservoir, of, a, and"
16076,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.127659574,"it, the, of, human, bat, reservoir"
16077,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.127659574,"the, identity, of, is, with, and"
16078,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.127659574,"is, that, the, primary, be, sars-cov-2"
16079,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.127659574,"that, the, was, as, of, a"
16080,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.127659574,"of, the, have, in, that, was"
16081,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.127659574,"of, not, but, that, the, a"
16082,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.127659574,"the, genome, of, coronavirus, to, bat"
16083,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.127659574,"to, by, and, was, the, sars-cov-2"
16084,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.127659574,"the, to, it, is, that, for"
16085,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.127659574,"that, sars-cov-2, a, to, it, host"
16086,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.127659574,"human, more, to, the, animal, than"
16087,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.127659574,"the, of, is, more, to, than"
16088,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.127659574,"the, reservoir, of, bat, it, human"
16089,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.127659574,"of, the, has, been, are, that"
16090,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.127659574,"that, sars-cov-2, have, and, the, genome"
16091,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.127659574,"to, virus, and, genome, the, sars-cov-2"
16092,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.127659574,"the, genetic, sequence, of, to, and"
16093,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.127659574,"the, of, from, to, related, sars"
16094,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.127659574,"from, to, in, the, may, human"
16095,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.127659574,"more, likely, to, that, and, humans"
16096,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.127659574,"of, that, it, is, to, and"
16097,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.127659574,"the, of, virus, to, that, and"
16098,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.127659574,"ratg13,, the, closest, was, of, bat"
16099,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.127659574,"of, genome, sequence, ratg13,, was, bat"
16100,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.127659574,"of, covid-19, virus, the, and, was"
16101,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.127659574,"with, and, of, the, in, 2019"
16102,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.127659574,"analysis, of, the, genome, with, and"
16103,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.127659574,"the, whole, genome, analysis, covid-19, virus"
16104,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.127659574,"the, covid-19, of, virus, genome, from"
16105,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.127659574,"the, of, sars-cov-2, to, is, that"
16106,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.127659574,"that, of, similar, to, the, sars-cov-2"
16107,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.127659574,"with, the, of, and, bat, human"
16108,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.127659574,"the, genome, of, to, coronavirus, bat"
16109,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.127659574,"the, of, sars, related, to, from"
16110,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.127659574,"the, genome, bat, and, sequence, a"
16111,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.127659574,"of, sars-cov-2, and, sars-cov, from, bat"
16112,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.127659574,"sars-cov-2, and, bat, identity, the, of"
16113,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.127659574,"a, coronavirus, identified, from, the, pangolin"
16114,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.127659574,"genome, analysis, of, the, with, and"
16115,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.127659574,"a, of, sars-cov-2, with, novel, that"
16116,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.127659574,"of, the, huanan, seafood, market,, that"
16117,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.127659574,"bats, which, can, be, species, to, as, and, in, et, may, 2020)"
16118,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.127659574,"the, has, been, to, of, is"
16119,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.127659574,"the, of, with, that, at, in"
16120,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.127659574,"the, cases, that, could, be, market,"
16121,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.127659574,"that, of, the, huanan, seafood, market,"
16122,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.127659574,"the, reported, to, market,, that, of"
16123,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.127659574,"the, is, naturally, occurring, a, that"
16124,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.127659574,"the, of, lineage, b, and, sars-cov-2"
16125,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.127659574,"to, of, the, bats, and, was"
16126,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.127659574,"et, of, to, and, the, sars-cov-2"
16127,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.127659574,"to, sars-cov-2, a, from, was, the"
16128,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.127659574,"of, the, closest, was, bat, ratg13,"
16129,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.127659574,"the, of, sars-cov-2, to, a, in"
16130,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.127659574,"the, of, sars-cov-2, to, a, bat"
16131,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.127659574,"that, the, of, in, a, and"
16132,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.127659574,"sars-cov-2, from, a, as, between, and"
16133,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.127659574,"studies, the, to, and, a, high"
16134,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.127659574,"recent, to, the, viruses, and, of"
16135,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.127659574,"studies, have, the, a, of, and"
16136,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.127659574,"the, in, zoonotic, to, of, and"
16137,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.127659574,"recent, the, of, to, and, viruses"
16138,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.127659574,"and, in, to, the, of, sars-cov-2"
16139,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.127659574,"in, of, for, sars-cov-2, to, zoonotic"
16140,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.127659574,"with, genome, as, the, natural, host"
16141,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.127659574,"its, and, the, from, bats, a"
16142,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.127659574,"bats, the, natural, host, for, of"
16143,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.127659574,"of, it, the, sars-like, and, for"
16144,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.127659574,"the, of, natural, a, as, and"
16145,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.127659574,"the, sars-cov-2, of, is, to, that"
16146,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.127659574,"the, of, that, sars-cov-2, to, similar"
16147,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.127659574,"was, the, sars-cov-2, and, to, by"
16148,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.127659574,"the, sars-cov-2, and, genome, virus, to"
16149,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.127659574,"the, of, that, is, animal, by"
16150,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.127659574,"in, the, of, to, sars-cov-2, has"
16151,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.127659574,"of, the, sars-cov-2, in, from, and"
16152,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.127659574,"sars-cov-, 2, with, ratg13,, and, the"
16153,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.127659574,"that, and, pangolins, hosts, for, sars-cov-2"
16154,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.127659574,"the, was, to, and, that, sars-cov-2"
16155,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.127659574,"the, was, reported, to, that, in"
16156,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.127659574,"a, in, the, that, sars-cov-2, laboratory"
16157,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.127659574,"to, the, of, sars-cov-2, for, humans"
16158,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.127659574,"also, the, between, sars-cov-2, and, is"
16159,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.127659574,"sars-cov-2, also, to, and, the, of"
16160,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.127659574,"the, that, to, a, of, and"
16161,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.127659574,"the, and, of, evidence, a, to"
16162,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.127659574,"to, that, the, of, and, evidence"
16163,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.127659574,"the, was, this, that, in, of"
16164,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.127659574,"the, of, bats, natural, host, for"
16165,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.127659574,"from, genome, the, of, covid-19, virus"
16166,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.127659574,"the, to, sars-cov-2, in, of, a"
16167,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.127659574,"bats, as, the, of, for, and"
16168,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.127659574,"bats, the, most, as, of, and"
16169,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.127659574,"the, to, that, and, including, sars-cov-2"
16170,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.127659574,"the, sars-cov-2, and, to, that, bat"
16171,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.127659574,"sars-cov-2, related, to, bat, genetic, which"
16172,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.127659574,"sars-cov-2, is, to, the, bat, which"
16173,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.127659574,"to, have, with, the, of, human"
16174,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.127659574,"the, of, to, human, ace2, that"
16175,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.127659574,"that, have, of, with, to, the"
16176,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.127659574,"these, were, human, in, to, animal"
16177,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.127659574,"due, to, the, with, a, sars-cov-2"
16178,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.127659574,"these, bat, coronaviruses,, with, sars-cov-2, than"
16179,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.127659574,"the, sars-cov-2, with, other, coronaviruses, to"
16180,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.127659574,"that, sars-cov-2, is, be, the, primary"
16181,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.127659574,"the, at, huanan, market, was, and"
16182,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.127659574,"a, from, was, at, seafood, market, in, wuhan, hubei, the, to, of"
16183,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.127659574,"a, by, who, market, in, wuhan, that, the, is, to, of, were"
16184,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.127659574,"the, of, evidence, a, and, to"
16185,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.127659574,"the, covid-19, to, and, a, one"
16186,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.127659574,"the, that, is, in, lineage, of"
16187,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.127659574,"infected, to, humans, with, the, sars-cov-2"
16188,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.127659574,"that, the, virus, to, humans, through"
16189,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.127659574,"that, sars-cov-2, the, with, virus, to"
16190,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.127659574,"the, in, a, to, of, and"
16191,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.127659574,"that, the, of, to, human, ace2"
16192,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.127659574,"to, that, of, sars-cov-2, the, protein"
16193,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.127659574,"have, been, of, one, the, for"
16194,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.127659574,"it, that, the, for, to, is"
16195,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.127659574,"in, the, that, its, a, human"
16196,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.127659574,"the, human, from, in, to, may"
16197,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.127659574,"the, to, which, a, from, is"
16198,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.127659574,"the, to, sars-cov-2,, that, not, from"
16199,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.127659574,"virus, the, was, to, that, sars-cov-2"
16200,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.127659574,"also, that, the, of, to, an"
16201,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.127659574,"of, the, and, sars-cov-2, a, with"
16202,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.127659574,"the, covid-19, and, one, a, to"
16203,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.127659574,"the, genetic, and, of, sequence, to"
16204,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.127659574,"the, analysis, and, that, which, to"
16205,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.127659574,"that, the, and, to, from, animals"
16206,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.127659574,"that, the, of, in, to, and"
16207,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.127659574,"of, to, the, in, that, virus"
16208,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.127659574,"virus, that, humans, through, to, the"
16209,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.127659574,"and, to, the, that, originated, in"
16210,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.127659574,"in, wuhan, the, of, virus, and"
16211,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.127659574,"in, the, of, to, that, virus"
16212,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.127659574,"to, the, in, covid-19, wuhan,, china"
16213,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.127659574,"was, that, the, in, have, of"
16214,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.127659574,"is, and, it, that, of, to"
16215,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.127659574,"and, virus, the, covid-19, was, of"
16216,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.127659574,"the, of, for, it, sars-like, and"
16217,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.127659574,"the, covid-19, to, in, wuhan,, china"
16218,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.127659574,"of, the, to, market,, that, was"
16219,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.127659574,"of, reported, to, the, market,, that"
16220,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.127659574,"reported, that, the, was, to, in"
16221,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.127659574,"the, that, of, natural, is, or"
16222,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.127659574,"are, to, in, bats, or, be"
16223,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.127659574,"and, species, can, be, as, et, 2020), to, which, may, in, bats"
16224,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.127659574,"in, the, market, and, a, of"
16225,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.127659574,"in, from, of, sars-cov-2, and, the"
16226,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.127659574,"the, sars-cov-2, and, guangdong, is, viruses"
16227,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.127659574,"he, of, virus, at, the, from"
16228,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.127659574,"is, that, a, the, covid-19, of"
16229,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.127659574,"from, a, is, to, the, which"
16230,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.127659574,"96.2%, a, genome, sequence, ratg13,, bat"
16231,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.127659574,"a, the, has, been, to, have"
16232,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.127659574,"a, it, that, sars-cov-2, to, host"
16233,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.127659574,"the, is, an, with, number, of"
16234,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.127659574,"a, of, the, that, not, but"
16235,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.127659574,"human, and, of, natural, the, virus"
16236,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.127659574,"that, the, is, sars-cov-2, laboratory, or"
16237,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.127659574,"the, of, as, a, natural, and"
16238,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.127659574,"is, and, origin, of, the, in"
16239,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.127659574,"coronaviruses,, with, sars-cov-2, than, these, bat"
16240,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.127659574,"to, the, hypothesis, that, from, origin"
16241,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.127659574,"to, has, that, by, the, and"
16242,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.127659574,"other, coronaviruses, to, with, sars-cov-2, the"
16243,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.127659574,"sars-cov-2, and, sars-cov, of, from, bat"
16244,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.127659574,"the, that, is, a, naturally, occurring"
16245,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.127659574,"that, the, of, evidence, and, to"
16246,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.127659574,"studies, based, on, the, that, sars-cov-2"
16247,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.127659574,"the, and, all, bat, that, to"
16248,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.127659574,"and, that, from, the, bat, coronavirus"
16249,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.127659574,"the, to, that, and, coronavirus, from"
16250,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.127659574,"that, and, hosts, for, sars-cov-2, pangolins"
16251,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.127659574,"whole, genome, analysis, the, covid-19, virus"
16252,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.127659574,"from, hubei, wuhan, to, at, the, seafood, market, in, of, a, was"
16253,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.127659574,"the, market, is, wuhan, that, in, of, were, to, by, who, a"
16254,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.127659574,"virus, the, to, bat, and, that"
16255,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.127659574,"of, genome, sequence, was, bat, ratg13,"
16256,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.127659574,"genome, 96.2%, sequence, bat, ratg13,, a"
16257,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.127659574,"animals, that, could, be, with, sars-cov-2"
16258,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.127659574,"with, sars-cov-2, that, are, hosts, for"
16259,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.127659574,"sars-cov-2, et, and, to, the, of"
16260,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.127659574,"the, and, ratg13,, with, sars-cov-, 2"
16261,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.127659574,"been, one, of, the, for, have"
16262,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.127659574,"the, of, with, a, and, sars-cov-2"
16263,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.127659574,"the, are, viruses, in, or, bats"
16264,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.127659574,"the, whole, genome, that, and, to"
16265,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.127659574,"or, bats, are, in, to, be"
16266,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.127659574,"that, hosts, for, sars-cov-2, are, with"
16267,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.127659574,"coronavirus, and, been, the, of, from"
16268,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.127659574,"this, sars-cov-2, and, the, viruses, that"
16269,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.127659574,"that, the, originated, in, and, to"
16270,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.127659574,"that, the, sars-cov-2, and, this, viruses"
16271,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.127659574,"that, sars-cov-2, the, and, similarity, to"
16272,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.127659574,"bat, to, is, which, sars-cov-2, the"
16273,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.127659574,"this, that, sars-cov-2, when, the, bats"
16274,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.127659574,"the, sars-cov-2, is, also, and, between"
16275,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.127659574,"viruses, the, sars-cov-2, is, guangdong, and"
16276,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.127659574,"the, virus, in, and, wuhan, of"
16277,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.127659574,"the, of, sars-cov-2, to, also, and"
16278,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.127659574,"the, to, sars-cov-2, of, a, bat"
16279,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.127659574,"that, sars-cov-2, with, has, and, to"
16280,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.127659574,"the, of, is, and, identity, with"
16281,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.127659574,"studies, have, the, of, a, and"
16282,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.127659574,"the, of, that, sars-cov-2, to, virus"
16283,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.127659574,"between, and, the, of, bat, in"
16284,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.127659574,"from, to, sars-cov-2,, the, that, not"
16285,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.127659574,"this, when, the, that, bats, sars-cov-2"
16286,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.127659574,"that, sars-cov-2, to, the, origin, of"
16287,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.127659574,"a, that, the, laboratory, in, sars-cov-2"
16288,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.127659574,"the, number, of, to, it, is"
16289,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.127659574,"with, the, of, an, number, is"
16290,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.127659574,"to, that, sars-cov-2, a, of, origin"
16291,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.127659574,"a, of, sars-cov-2, with, that, novel"
16292,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.127659574,"sars-cov-2, to, for, in, zoonotic, of"
16293,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.127659574,"the, of, sars-cov-2, protein, to, that"
16294,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.127659574,"the, of, an, to, that, also"
16295,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.127659574,"the, of, is, more, than, to"
16296,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.127659574,"identity, sars-cov-2, and, the, of, bat"
16297,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.127659574,"the, that, sars-cov-2, is, or, laboratory"
16298,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.12745098,"on, 2019,, the, hospital, of, and, an, with, patients, exposure, at, huanan, seafood"
16299,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.12745098,"an, the, huanan, seafood, with, at, on, 2019,, and, of, hospital, patients, exposure"
16300,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.127272727,"bat, in, closely, viruses, a, to, genetic"
16301,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.127272727,"and, species, are, known, to, bats, be"
16302,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.127272727,"the, of, infected, to, in, it, is"
16303,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.127272727,"the, to, sars-cov-2, was, in, of, a"
16304,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.127272727,"a, amino, acid, the, be, to, sars-cov-2"
16305,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.127272727,"the, s1, amino, acid, of, is, to"
16306,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.127272727,"sars-cov-2, is, sequence, and, bat, to, in"
16307,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.127272727,"have, and, to, the, of, sars-cov-2, origin"
16308,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.127272727,"to, origin, the, that, between, and, be"
16309,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.127272727,"sars-cov-2, of, the, as, intermediate, hosts, for"
16310,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.127272727,"intermediate, hosts, for, sars-cov-2, to, humans, the"
16311,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.127272727,"of, the, in, it, is, to, infected"
16312,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.127272727,"of, and, the, to, species, including, humans,"
16313,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.127272727,"the, was, in, and, that, for, a"
16314,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.127272727,"that, the, in, and, transmitted, to, humans"
16315,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.127272727,"the, in, found, bats, from, is, to"
16316,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.127272727,"to, sars-cov-2, a, from, and, transmitted, as"
16317,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.127272727,"sars-cov-2, to, have, likely, in, host, bat"
16318,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.127272727,"and, the, of, to, be, that, sars-cov-2"
16319,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.127272727,"suggests, that, the, in, to, humans, of"
16320,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.127272727,"other, that, sars-cov-2, and, not, from, laboratory"
16321,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.127272727,"with, bat, that, the, as, and, similarity"
16322,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.127272727,"to, the, coronavirus, and, that, a, covid-19"
16323,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.127272727,"the, a, of, to, with, that, and"
16324,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.127272727,"that, a, of, with, to, and, the"
16325,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.127272727,"they, in, to, of, the, virus, which"
16326,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.127272727,"the, of, coronavirus, that, from, to, and"
16327,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.127272727,"sars-cov-2, transmitted, from, to, a, as, and"
16328,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.127272727,"the, that, from, was, to, as, and"
16329,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.127272727,"that, the, of, to, with, a, and"
16330,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.127272727,"a, virus, that, with, to, the, for"
16331,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.127272727,"genome, from, the, bat, of, virus, and"
16332,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.127272727,"the, of, to, that, pangolin, which, virus"
16333,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.127272727,"exhibit, to, sars-cov-2, the, spike, protein, of"
16334,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.127272727,"the, by, was, and, to, of, on"
16335,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.127272727,"of, to, the, in, which, they, virus"
16336,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.127272727,"in, the, of, is, to, which, virus"
16337,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.127272727,"the, that, likely, jumped, to, humans, and"
16338,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.127272727,"the, to, may, be, is, for, and"
16339,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.127272727,"of, the, in, were, with, seafood, market"
16340,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.127272727,"the, as, that, with, bat, and, similarity"
16341,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.127272727,"the, that, sars-cov-2, with, of, and, similarity"
16342,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.127272727,"have, and, to, the, of, sars-cov-2, is"
16343,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.127272727,"to, and, of, bats,, it, is, that"
16344,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.127272727,"the, by, was, and, of, with, pneumonia"
16345,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.127272727,"many, and, zoonotic, cause, in, such, as"
16346,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.127272727,"the, to, that, of, and, coronavirus, from"
16347,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.127272727,"to, that, from, and, was, the, as"
16348,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.127272727,"the, of, that, more, to, bat, genome"
16349,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.127272727,"that, other, not, sars-cov-2, from, and, laboratory"
16350,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.127272727,"comparative, analysis, on, the, a, from, that"
16351,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.127272727,"on, the, comparative, analysis, that, from, a"
16352,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.127272727,"analysis, that, the, in, intermediate, hosts, of"
16353,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.127272727,"that, are, the, similar, to, a, bat"
16354,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.127272727,"and, sars-cov-2, is, to, bat, in, sequence"
16355,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.127272727,"in, can, be, that, between, and, bat"
16356,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.127272727,"the, that, sars-cov-2, at, of, and, similarity"
16357,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.127272727,"a, of, the, in, was, to, sars-cov-2"
16358,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.127272727,"a, of, sars-cov-2, in, an, the, to"
16359,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.127272727,"in, the, a, was, that, and, for"
16360,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.127272727,"sars-cov-2, the, rbd, in, related, that, of"
16361,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.127272727,"hypothesis, to, the, that, ratg13, but, this"
16362,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.127272727,"of, covs, and, which, have, genomic, to"
16363,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.127272727,"is, that, bats, the, sars-cov-2, to, a"
16364,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.127272727,"the, of, with, and, sequences, in, collected"
16365,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.127272727,"that, of, a, found, in, with, sars-cov-2"
16366,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.127272727,"a, genome, in, that, virus, of, found"
16367,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.127272727,"the, has, been, a, of, that, by"
16368,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.127272727,"sars-cov-2, ace2, in, of, species, and, the"
16369,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.127272727,"the, to, from, bats, in, is, found"
16370,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.127272727,"the, most, one, horseshoe, bats, in, and"
16371,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.127272727,"to, sars-cov-2,, by, is, similar, at, the"
16372,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.127272727,"rbd, of, sars-cov-2, to, the, emergence, these"
16373,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.127272727,"it, can, be, that, the, and, of"
16374,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.127272727,"the, of, sars-cov-2, as, intermediate, hosts, for"
16375,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.127272727,"in, ace2, species, of, sars-cov-2, and, the"
16376,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.127272727,"a, that, the, mice, and, in, sars-cov-2"
16377,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.127272727,"that, sars-cov-2, also, and, a, the, of"
16378,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.127272727,"to, the, sars-cov-2, intermediate, hosts, for, humans"
16379,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.127272727,"the, in, pangolins, rbd, to, that, sars-cov-2"
16380,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.127272727,"the, in, that, hosts, for, sars-cov-2, than"
16381,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.127272727,"other, that, sars-cov-2, to, and, on, the"
16382,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.127272727,"the, to, be, amino, in, rbd, than"
16383,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.127272727,"that, a, was, the, sars-cov-2, and, to"
16384,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.127272727,"sars-cov-2, in, a, mice, and, that, the"
16385,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.127272727,"the, amino, acid, sars-cov-2, to, be, a"
16386,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.127272727,"to, the, and, is, may, be, for"
16387,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.127272727,"the, with, in, seafood, market, were, of"
16388,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.127272727,"bats, are, the, natural, reservoir, of, for"
16389,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.127272727,"the, of, covid-19, in, closely, a, to"
16390,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.127272727,"the, and, in, horseshoe, bats, most, one"
16391,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.127272727,"to, the, of, bats, and, as, sars-cov-2"
16392,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.127272727,"closely, to, bat, in, a, genetic, viruses"
16393,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.127272727,"the, covid-19, of, to, a, closely, in"
16394,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.127272727,"at, the, is, similar, to, sars-cov-2,, by"
16395,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.127272727,"the, of, and, that, are, similar, to"
16396,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.127272727,"that, of, sars-, cov-2, to, is, the"
16397,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.127272727,"the, rbd, and, to, that, are, of"
16398,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.127272727,"on, the, of, and, was, to, by"
16399,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.127272727,"and, by, pneumonia, with, the, was, of"
16400,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.127272727,"this, evidence, suggests, that, palm, civets, were, from, in, the, a, or, and, of"
16401,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.127272727,"this, suggests, the, as, intermediate, host, for"
16402,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.127272727,"the, of, and, civets, were, that, from, palm, a, in, this, evidence, suggests, or"
16403,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.127272727,"the, that, known, are, and, in, at"
16404,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.127272727,"the, sequences, of, and, collected, in, with"
16405,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.127272727,"at, are, known, and, in, the, that"
16406,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.127272727,"the, virus, for, a, to, with, that"
16407,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.127272727,"viruses, to, the, in, of, and, a"
16408,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.127272727,"exhibit, to, the, spike, protein, of, sars-cov-2"
16409,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.127272727,"shows, that, sars-cov-2, the, of, similarity, to"
16410,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.127272727,"that, sars-cov-2, to, pangolins, the, in, rbd"
16411,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.127272727,"in, the, of, that, sars-cov-2, related, rbd"
16412,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.127272727,"in, the, that, transmitted, to, humans, and"
16413,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.127272727,"in, humans, the, of, suggests, that, to"
16414,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.127272727,"analysis, in, the, of, that, intermediate, hosts"
16415,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.127272727,"to, that, the, of, bats, and, hosts"
16416,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.127272727,"the, of, that, most, to, bat, and"
16417,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.127272727,"the, covid-19, to, coronavirus, and, that, a"
16418,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.127272727,"a, of, viruses, in, and, to, the"
16419,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.127272727,"of, to, the, emergence, in, these, animals"
16420,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.127272727,"have, that, bats, the, a, of, and"
16421,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.127272727,"bats, are, the, natural, reservoir, for, of"
16422,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.127272727,"bats, and, species, are, known, to, be"
16423,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.127272727,"including, the, species, humans,, to, of, and"
16424,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.127272727,"the, likely, to, that, and, jumped, humans"
16425,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.127272727,"the, that, of, has, been, by, a"
16426,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.127272727,"of, that, most, to, the, bat, and"
16427,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.127272727,"that, has, the, at, of, virus, to"
16428,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.127272727,"the, has, a, that, not, of, but"
16429,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.127272727,"and, a, the, natural, of, human, as"
16430,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.127272727,"the, origin, of, to, have, and, sars-cov-2"
16431,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.127272727,"have, the, sars-cov-2, and, of, is, to"
16432,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.127272727,"the, origin, be, to, that, between, and"
16433,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.127272727,"this, hypothesis, the, that, to, ratg13, but"
16434,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.127272727,"these, the, of, rbd, to, emergence, sars-cov-2"
16435,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.127272727,"to, the, in, of, these, animals, emergence"
16436,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.127272727,"and, also, a, sars-cov-2, the, genomes, to"
16437,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.127272727,"that, a, virus, found, in, genome, of"
16438,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.127272727,"the, bat, that, a, are, similar, to"
16439,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.127272727,"that, bats, to, is, a, sars-cov-2, the"
16440,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.127272727,"the, to, sars-cov-2, in, an, of, a"
16441,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.127272727,"the, sars-cov-2, genomes, to, a, also, and"
16442,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.127272727,"have, of, covs, to, and, which, genomic"
16443,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.127272727,"the, of, to, sars-cov-2, that, pangolin, virus"
16444,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.127272727,"that, the, of, bats, and, more, sars-cov-2"
16445,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.127272727,"sars-cov-2, have, host, to, likely, in, bat"
16446,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.127272727,"that, hosts, for, sars-cov-2, than, the, in"
16447,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.127272727,"the, bats, to, as, of, sars-cov-2, and"
16448,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.127272727,"that, the, bats, and, to, hosts, of"
16449,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.127272727,"that, the, of, sars-cov-2, and, more, bats"
16450,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.127272727,"the, virus, genome, of, from, and, bat"
16451,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.127272727,"sars-cov-2, also, a, of, and, that, the"
16452,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.127272727,"that, and, sars-cov-2, to, other, on, the"
16453,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.127272727,"the, genome, of, that, to, bat, more"
16454,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.127272727,"the, have, bats, of, and, that, a"
16455,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.127272727,"with, that, the, of, sars-cov-2, and, similarity"
16456,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.127272727,"that, the, similarity, of, sars-cov-2, and, at"
16457,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.127272727,"between, and, bat, can, be, that, in"
16458,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.127272727,"and, the, of, it, can, be, that"
16459,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.127272727,"the, virus, of, which, to, that, pangolin"
16460,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.127272727,"in, to, is, of, the, virus, which"
16461,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.127272727,"that, of, pangolin, virus, to, the, sars-cov-2"
16462,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.127272727,"for, the, intermediate, host, this, suggests, as"
16463,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.127272727,"of, at, the, in, a, that, animal"
16464,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.127272727,"cause, many, zoonotic, such, as, in, and"
16465,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.127272727,"the, of, at, that, a, in, animal"
16466,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.127272727,"be, to, than, the, amino, in, rbd"
16467,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.127272727,"the, of, and, are, to, rbd, that"
16468,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.127272727,"of, has, not, but, that, the, a"
16469,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.127272727,"is, and, bats,, it, that, of, to"
16470,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.127272727,"the, amino, acid, s1, to, of, is"
16471,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.127118644,"in, 2013,, a, of, wiv, researchers, to, sars-related, yunnan, the, for, sars, closely, related, virus"
16472,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.127118644,"the, of, closely, related, for, in, 2013,, wiv, researchers, a, virus, to, sars, sars-related, yunnan"
16473,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.126984127,"the, of, and, have, sars-cov-2, is, which, to"
16474,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.126984127,"the, is, by, also, a, sequence, that, in"
16475,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.126984127,"and, the, of, to, can, be, that, sars-cov-2"
16476,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.126984127,"that, the, virus, in, bats, and, to, of"
16477,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.126984127,"are, in, animals, to, the, and, was, transmitted"
16478,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.126984127,"that, a, with, to, and, are, the, for"
16479,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.126984127,"are, a, coronaviruses, to, in, sars-cov-2, bat, and"
16480,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.126984127,"and, a, similarity, between, sars-cov-2, in, an, to"
16481,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.126984127,"the, of, as, a, that, from, humans, to"
16482,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.126984127,"the, of, sars-cov-2, into, humans, zoonotic, from, at"
16483,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.126984127,"the, genomic, diversity, sars-cov-2, at, that, in, and"
16484,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.126984127,"of, the, from, sars-cov-2, at, zoonotic, into, humans"
16485,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.126984127,"in, the, market, animal, and, presence, of, sars-cov-2"
16486,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.126984127,"in, the, a, that, to, more, closely, related"
16487,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.126984127,"hosts, of, and, in, respiratory, syndrome, middle, east"
16488,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.126984127,"the, that, sars-cov-2, genomic, diversity, and, at, in"
16489,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.126984127,"the, presence, of, animal, and, market, sars-cov-2, in"
16490,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.126984127,"the, and, were, that, virus, from, taken, this"
16491,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.126984127,"and, samples, the, huanan, seafood, that, this, from"
16492,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.126984127,"a, for, the, of, bat, and, identity, with"
16493,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.126984127,"the, of, a, coronavirus, from, pangolin, that, for"
16494,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.126984127,"the, sars-cov-2, and, which, have, to, of, is"
16495,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.126984127,"in, the, was, are, transmitted, animals, to, and"
16496,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.126984127,"and, in, were, to, that, the, likely, natural"
16497,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.126984127,"of, the, december, and, 2019, huanan, seafood, market,"
16498,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.126984127,"and, may, be, intermediate, for, to, on, the"
16499,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.126984127,"the, for, a, of, identity, with, and, bat"
16500,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.126984127,"of, the, is, bat, a, high, as, for"
16501,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.126984127,"sequence, sars-cov-2, and, sars-cov, with, the, of, bat"
16502,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.126984127,"with, the, of, bats, as, a, natural, and"
16503,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.126984127,"sequence, with, bat, the, of, sars-cov-2, and, sars-cov"
16504,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.126984127,"the, for, a, of, that, coronavirus, from, pangolin"
16505,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.126984127,"the, of, protein, most, likely, on, a, that"
16506,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.126984127,"that, a, of, pangolin, the, intermediate, hosts, for"
16507,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.126984127,"from, a, is, to, in, which, that, may"
16508,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.126984127,"of, the, that, cases, huanan, seafood, market,, suggesting"
16509,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.126984127,"found, in, which, to, that, of, sars-cov-2, ratg13"
16510,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.126984127,"and, a, the, bats, natural, of, with, as"
16511,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.126984127,"for, the, were, intermediate, host, a, in, with"
16512,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.126984127,"the, of, can, be, to, that, and, sars-cov-2"
16513,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.126984127,"the, in, and, therefore, that, or, hosts, for"
16514,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.126984127,"to, on, the, and, may, be, intermediate, for"
16515,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.126984127,"the, to, live, animal, in, and, were, at"
16516,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.126984127,"of, sequences, to, a, from, rhinolophus, in, china."
16517,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.126984127,"sars-cov-2, of, natural, the, zoonotic, to, in, virus"
16518,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.126984127,"a, closely, to, recombination, events, in, the, bat"
16519,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.126984127,"sars-cov-2, to, a, are, and, coronaviruses, in, bat"
16520,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.126984127,"the, bat, in, recombination, events, closely, a, to"
16521,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.126984127,"huanan, seafood, market,, the, december, 2019, and, of"
16522,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.126984127,"of, cases, the, huanan, seafood, market,, suggesting, that"
16523,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.126984127,"that, were, taken, from, the, and, this, virus"
16524,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.126984127,"were, a, intermediate, host, for, with, the, in"
16525,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.126984127,"in, a, related, that, the, more, closely, to"
16526,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.126984127,"in, the, both, from, and, a, palm, civet"
16527,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.126984127,"samples, that, from, the, huanan, seafood, and, this"
16528,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.126984127,"on, the, protein, of, a, that, most, likely"
16529,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.126984127,"is, a, from, to, which, that, may, in"
16530,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.126984127,"a, for, the, as, of, bat, is, high"
16531,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.126984127,"the, that, these, of, is, or, as, for"
16532,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.126984127,"evidence, that, the, of, as, hosts, for, origin"
16533,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.126984127,"bats, the, of, virus, and, in, that, to"
16534,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.126984127,"animal, to, were, live, and, in, at, the"
16535,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.126984127,"of, that, the, is, these, as, or, for"
16536,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.126984127,"found, in, of, which, that, sars-cov-2, to, ratg13"
16537,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.126984127,"is, also, that, a, by, the, sequence, in"
16538,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.126984127,"to, from, a, of, sequences, in, rhinolophus, china."
16539,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.126984127,"sars-cov-2, an, to, a, similarity, between, and, in"
16540,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.126984127,"the, a, that, are, to, and, with, for"
16541,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.126984127,"the, of, a, pangolin, that, intermediate, hosts, for"
16542,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.126984127,"the, sequences, cluster, and, bat, or, pangolin, of"
16543,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.126984127,"in, and, that, the, therefore, or, hosts, for"
16544,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.126984127,"this, the, in, fig., that, are, sars-cov-2, than"
16545,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.126984127,"that, sars-cov-2, are, pangolin, cov, and, the, origin"
16546,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.126984127,"in, fig., are, sars-cov-2, this, that, the, than"
16547,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.126984127,"of, the, bat, and, or, cluster, sequences, pangolin"
16548,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.126984127,"of, evidence, that, the, origin, as, hosts, for"
16549,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.126984127,"are, and, sars-cov-2, cov, pangolin, that, the, origin"
16550,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.126984127,"in, the, palm, a, from, both, and, civet"
16551,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.126984127,"the, has, to, that, direct, of, sars-cov-2,, but"
16552,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.126984127,"and, in, middle, east, respiratory, syndrome, of, hosts"
16553,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.126984127,"the, natural, were, likely, to, that, in, and"
16554,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.126984127,"to, that, has, the, but, direct, of, sars-cov-2,"
16555,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.126984127,"the, of, natural, zoonotic, sars-cov-2, to, virus, in"
16556,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.126760563,"are, in, to, is, of, the, virus, bats, and"
16557,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.126760563,"to, can, be, with, of, and, in, bats, their"
16558,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.126760563,"this, of, and, viruses, are, by, a, in, the"
16559,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.126760563,"the, of, and, were, that, a, in, with, to"
16560,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.126760563,"cases, and, the, huanan, that, of, in, a, worobey"
16561,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.126760563,"bats, are, the, of, is, virus, and, in, to"
16562,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.126760563,"sars-cov-2, sequence, and, bat, as, et, al.,, 2020), that"
16563,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.126760563,"the, of, confirmed, that, virus, identical, to, and, sequence"
16564,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.126760563,"and, to, be, that, of, is, very, likely, sars-cov-2"
16565,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.126760563,"sequence, bat, that, as, sars-cov-2, et, al.,, 2020), and"
16566,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.126760563,"share, which, that, of, sars-cov-2, both, and, acid, sequences"
16567,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.126760563,"the, of, with, huanan, seafood, and, these, in, at"
16568,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.126760563,"sars-cov-2, in, a, of, species, that, the, with, intermediate"
16569,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.126760563,"that, intermediate, sars-cov-2, transmission, to, humans, the, in, with"
16570,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.126760563,"that, of, intermediate, a, in, with, sars-cov-2, species, the"
16571,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.126760563,"that, transmission, to, humans, intermediate, in, with, sars-cov-2, the"
16572,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.126760563,"a, of, the, this, by, and, are, in, viruses"
16573,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.126760563,"in, than, the, sars, investigators, live, animal, of, that, did, at, also, virus, was, to, least, different, a"
16574,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.126760563,"that, sars, a, the, virus, was, animal, than, of, in, at, least, different, investigators, also, did, to, live"
16575,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.126760563,"that, the, of, were, in, to, with, a, and"
16576,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.126760563,"confirmed, the, and, of, sequence, virus, identical, to, that"
16577,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.126760563,"the, a, to, live, animal, in, markets, and, at"
16578,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.126760563,"in, the, of, and, with, these, at, huanan, seafood"
16579,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.126760563,"worobey, that, the, of, cases, in, a, and, huanan"
16580,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.126760563,"bats, of, can, and, be, in, with, their, to"
16581,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.126760563,"live, animal, at, markets, a, and, in, the, to"
16582,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.126760563,"that, acid, sequences, of, sars-cov-2, and, both, which, share"
16583,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.126760563,"is, very, and, likely, that, of, sars-cov-2, to, be"
16584,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.126582278,"and, can, also, into, with, are, to, bats, a, be"
16585,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.126582278,"in, a, to, the, are, that, was, transmitted, from, for"
16586,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.126582278,"from, and, it, to, was, not, that, sars-cov-2, in, laboratory"
16587,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.126582278,"in, the, a, was, that, are, transmitted, from, to, for"
16588,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.126582278,"sars-cov, reservoir, as, and, it, possibility, for, the, of, a"
16589,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.126582278,"of, with, 2019,, exposure, reported, and, the, huanan, market., in"
16590,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.126582278,"sars-cov-2, of, the, and, with, furin, cleavage, site, to, in"
16591,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.126582278,"the, for, of, as, viruses, sars, bats, progenitor, animal, and"
16592,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.126582278,"a, by, using, seafood, wuhan, that, the, of, were, found"
16593,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.126582278,"bats, as, the, animal, for, progenitor, viruses, of, sars, and"
16594,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.126582278,"2019,, in, the, of, and, with, reported, exposure, huanan, market."
16595,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.126582278,"bats, are, also, a, can, and, be, with, to, into"
16596,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.126582278,"and, from, r., sinicus, to, that, the, of, likely, hosts"
16597,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.126582278,"that, not, it, was, sars-cov-2, to, from, and, in, laboratory"
16598,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.126582278,"a, for, the, sars-cov, possibility, as, reservoir, of, and, it"
16599,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.126582278,"to, that, the, of, and, may, have, as, for, sars-cov-2"
16600,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.126582278,"that, the, to, by, be, this, appears, hypothesis, origin, and"
16601,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.126582278,"hypothesis, to, origin, the, that, by, and, this, appears, be"
16602,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.126582278,"in, of, sars-cov-2, to, be, with, origin, suggesting, that, may"
16603,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.126582278,"by, a, of, the, found, that, were, wuhan, using, seafood"
16604,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.126582278,"as, and, to, for, the, of, that, sars-cov-2, may, have"
16605,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.126582278,"that, sars-cov-2, to, suggesting, may, be, with, in, of, origin"
16606,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.126582278,"the, of, that, likely, from, to, hosts, sinicus, and, r."
16607,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.126582278,"to, sars-cov-2, of, in, the, and, furin, cleavage, site, with"
16608,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.126436782,"in, a, of, to, the, are, virus, that, is, for, as"
16609,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.126436782,"the, huanan, market, that, in, of, cases, case, and, with, early"
16610,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.126436782,"are, a, for, as, the, of, is, virus, in, that, to"
16611,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.126436782,"et, that, the, sars-cov-2, to, these, therefore,, be, of, natural, and"
16612,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.126436782,"of, with, had, a, exposure, to, reported, the, market, only, in"
16613,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.126436782,"the, of, to, sars-cov-like, is, likely, that, bats, as, reservoir, for"
16614,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.126436782,"the, of, with, case, and, early, cases, huanan, market, that, in"
16615,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.126436782,"that, 2, have, by, a, of, with, to, and, the, for"
16616,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.126436782,"a, of, market, in, with, only, had, the, reported, exposure, to"
16617,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.126436782,"the, to, for, of, as, reservoir, sars-cov-like, is, likely, that, bats"
16618,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.126436782,"these, are, to, on, the, in, and, bats, or, could, be"
16619,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.126436782,"these, and, the, of, to, et, therefore,, be, that, sars-cov-2, natural"
16620,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.126436782,"the, that, have, for, of, 2, to, by, and, with, a"
16621,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.126436782,"or, bats, on, the, could, be, these, are, to, and, in"
16622,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.126315789,"cases, the, huanan, market,, and, of, to, that, were, covid-19, more, than"
16623,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.126315789,"the, of, a, to, animal, in, wet, wild, market, virus, palm, civet"
16624,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.126315789,"more, than, of, the, covid-19, cases, were, to, huanan, market,, and, that"
16625,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.126315789,"a, of, wet, market, in, wild, animal, palm, civet, the, to, virus"
16626,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.126213592,"from, the, for, to, a, virus, that, 99%, with, bat, and, of, coronavirus"
16627,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.126213592,"in, of, for, sars-cov-2, were, found, to, with, coronavirus, that, zoonotic, events, may"
16628,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.126213592,"in, a, to, coronaviruses, the, bat, coronaviruses,, and, more, closely, related, than, other"
16629,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.126213592,"a, other, closely, related, coronaviruses, to, in, coronaviruses,, more, than, the, bat, and"
16630,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.126213592,"the, virus, for, a, of, to, 99%, with, that, coronavirus, from, and, bat"
16631,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.126213592,"had, and, before, to, not, for, by, the, of, that, have, in, a"
16632,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.126213592,"the, that, have, in, for, of, before, to, by, and, a, not, had"
16633,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.126213592,"sars-cov-2, of, to, in, were, with, found, that, for, coronavirus, events, may, zoonotic"
16634,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.126126126,"the, to, in, a, of, as, sars, was, that, infected, virus, were, and, palm"
16635,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.126126126,"in, the, of, palm, as, sars, was, a, that, virus, infected, were, to, and"
16636,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.12605042,"from, the, team, was, for, first, to, a, live, virus, that, this, as, in, of"
16637,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.12605042,"in, the, same, of, a, to, bat, as, single, viruses, that, recombination, events, multiple, species"
16638,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.12605042,"by, the, discovery, of, a, sars-related, in, to, that, sars, virus,, researchers, virus, similar, for"
16639,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.12605042,"the, of, by, for, in, researchers, a, virus, similar, to, sars, discovery, sars-related, virus,, that"
16640,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.12605042,"in, a, team, of, to, the, virus, that, was, first, this, from, live, for, as"
16641,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.12605042,"that, the, of, multiple, bat, species, in, same, recombination, events, as, viruses, a, single, to"
16642,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.125786164,"a, of, the, investigators, studies, at, animal, live, in, an, to, sars, with, that, guangdong, province”, infections, coupled, suggested, not"
16643,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.125786164,"suggested, that, sars, a, the, an, animal, coupled, with, studies, of, in, at, guangdong, province”, investigators, infections, not, to, live"
16644,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.125,"are, other, sars-cov-2, to, and, viruses, in"
16645,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.125,"coronaviruses, are, viruses, to, and"
16646,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.125,"the, of, and, into, from, virus, human"
16647,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.125,"the, natural, of, and, viruses"
16648,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.125,"the, of, and, virus, into, from, human, this, humans"
16649,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.125,"the, of, and, this, from, viruses"
16650,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.125,"are, a, number, of"
16651,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.125,"species, reservoir, of, bat"
16652,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.125,"species, of, reservoir"
16653,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.125,"the, sars, viruses, in"
16654,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.125,"the, viruses, from, as"
16655,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.125,"the, coronaviruses, most, and, southeast, asia,"
16656,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.125,"to, be, bats, and, the"
16657,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.125,"the, species, and, animal"
16658,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.125,"the, known, and, of, to"
16659,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.125,"the, reservoir, and, to, of"
16660,"genetic sequencing has been used to show that  

COVID-19 exists in bats,",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.125,"genetic, to, in"
16661,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.125,"have, genetic, and, to, bat"
16662,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.125,"have, in, coronaviruses, such"
16663,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.125,"in, to, of, which, bats, and"
16664,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.125,"bats, to, of, sars-cov-2, and"
16665,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.125,"of, sars-cov-2, and, more, bats"
16666,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.125,"bats, of, many, and, which, to, in"
16667,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.125,"more, than, of, were, and"
16668,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.125,"genetic, and, by, bats, of"
16669,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.125,"bats, more, of, than"
16670,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.125,"the, sars-cov, and, sequences, are, similar, to"
16671,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.125,"the, and, are, sarbecovirus, sequences, sars-, cov-2, sars"
16672,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.125,"sars-cov-2, to, identical, genome"
16673,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.125,"in, more, to, than"
16674,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.125,"its, virus, to, in"
16675,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.125,"more, to, virus, in"
16676,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.125,"genome, is, more, than, to"
16677,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.125,"virus, is, to"
16678,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.125,"sars-cov-2, identical, to"
16679,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.125,"is, more, to, than"
16680,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.125,"clearly, is, a"
16681,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.125,"in, the, are"
16682,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.125,"also, in, the"
16683,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.125,"the, in, bats, of, emergence, china"
16684,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.125,"human, and, from, of, the, virus, into"
16685,"with the first case being linked to  

a seafood market","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.125,"with, the, being, to, a"
16686,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.125,"a, sars-cov-2, it, with, the, in"
16687,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.125,"sars-cov-2, is, a, with, infected, to, the"
16688,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.125,"t, that, of, sars-cov-2, a"
16689,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.125,"that, be, a, of"
16690,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.125,"t, been, that, sars-cov-2"
16691,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.125,"have, been, by, of, sars-cov-2, origin"
16692,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.125,"the, of, to, that, have, including, sars-cov-2"
16693,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.125,"of, genetic, to, that, sars-cov-2, the"
16694,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.125,"genetic, been, used, to, that"
16695,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.125,"have, the, genetic, sars-cov-2, of, to, that"
16696,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.125,"from, identified, coronavirus, which"
16697,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.125,"the, virus, for, covid-19, has, a, of, which, to, that, and"
16698,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.125,"such, and, genetically, to, not, for, the, of, that, sars-cov-2, have, in, a"
16699,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.125,"a, is, the, to, in, human, and"
16700,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.125,"a, between, sars-cov-2, and, the, of, bat, in"
16701,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.125,"have, the, of, human, to, a, and, which"
16702,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.125,"to, the, of, be, a, human, bat"
16703,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.125,"to, a, amino, acid, in, the, human"
16704,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.125,"the, coronaviruses, to, sars-cov-2, bat, in, and"
16705,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.125,"sars-cov-2, the, and, in, coronaviruses, nature,, of, is"
16706,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.125,"have, and, in, to, the, of, sars-cov-2, is"
16707,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.125,"in, the, a, highly, was, that, from, any"
16708,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.125,"that, was, sars-cov-2, from, is, any, in, laboratory"
16709,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.125,"that, from, the, also, virus, is"
16710,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.125,"the, sequence, that, sars-cov-2, is, highly"
16711,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.125,"a, sars-cov-2, because, genetic, the, in"
16712,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.125,"the, is, that, released, in, before, january, 2020, by, a, had"
16713,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.125,"sars-cov-2, is, a, virus, that, its, the"
16714,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.125,"virus, is, and, that"
16715,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.125,"a, that, virus, many, and"
16716,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.125,"and, that, sars-cov-2, a, with"
16717,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.125,"other, that, sars-cov-2, and, a"
16718,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.125,"of, the, that, to, coronaviruses"
16719,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.125,"that, the, of, to, human"
16720,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.125,"and, bat, to, the, viruses, that"
16721,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.125,"to, highly, genome, the, sars-cov-2"
16722,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.125,"the, to, that, sars-cov-2, bat"
16723,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.125,"the, to, bat, that, as"
16724,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.125,"that, sars-cov-2, bat, to, host"
16725,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.125,"the, that, sars-cov-2, with, to"
16726,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.125,"t, that, a, of, sars-cov-2"
16727,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.125,"a, that, the, was, it"
16728,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.125,"the, bat, identity, sars-cov-2"
16729,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.125,"is, it, that, of, sars-cov-2, to"
16730,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.125,"the, of, a, it, shares, genome"
16731,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.125,"the, a, of, that, whereas, to, bat"
16732,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.125,"the, to, that, sars-cov-2, is, of, bat, cov"
16733,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.125,"the, bat, of, cov"
16734,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.125,"to, of, it, is, that, bat"
16735,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.125,"ratg13,, the, of, is, to"
16736,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.125,"has, been, and, of, evolutionary"
16737,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.125,"of, natural, host, and"
16738,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.125,"of, genome, virus, and, bat"
16739,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.125,"virus, of, and, has, been"
16740,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.125,"has, been, genome, bat, and"
16741,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.125,"and, viruses, of, natural, the"
16742,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.125,"including, the, of, and"
16743,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.125,"the, viruses, are, of"
16744,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.125,"reservoir, of, the, a"
16745,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.125,"are, the, reservoir, a"
16746,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.125,"that, the, covid-19, virus, and, to"
16747,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.125,"showed, that, sars-cov-2, to, and"
16748,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.125,"the, identity, sars-cov-2, same, and"
16749,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.125,"and, sars-cov, is, of, bat"
16750,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.125,"of, to, is, in, with, sars-cov-2, the"
16751,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.125,"the, sequence, of, with, sars-cov-2"
16752,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.125,"to, the, whole, genome, in, and"
16753,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.125,"the, sars-cov-2, and, bat, is"
16754,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.125,"most, to, sars-cov-2"
16755,SARS-CoV-2 was created from SARS-CoV-2,Originating from reservoir of bat,0.125,from
16756,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",Originating from reservoir of bat,0.125,"bat, of"
16757,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",Originating from reservoir of bat,0.125,"of, bat, from"
16758,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.125,"sars-cov-2, the, of, that, have, to, including"
16759,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.125,"of, to, sars-cov-2, and, the, humans"
16760,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.125,"that, the, to, and, changes, sars-cov-2"
16761,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.125,"the, of, to, that, sars-cov-2, can"
16762,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",hese reservoirs are the bats,0.125,"the, are"
16763,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.125,"its, the, bats, a, in"
16764,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.125,"of, the, as, in, a"
16765,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.125,"the, of, bats, as, a, its"
16766,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.125,"the, that, of, has, a"
16767,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.125,"the, host, of, known, as"
16768,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.125,"the, of, zoonotic, and, been"
16769,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.125,"are, other, coronaviruses,, more, than, the, and"
16770,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.125,"the, of, in, is, also, to, bats"
16771,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.125,"the, is, that, virus, to, a, of, and"
16772,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.125,"to, a, recombination, of, in, bats, the, and, that, with"
16773,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.125,"for, recombination, and, that, in, the, of"
16774,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.125,"the, of, that, is, a, virus, in, for"
16775,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.125,"the, and, to, a, is, in, human"
16776,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.125,"the, was, that, in, and"
16777,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.125,"the, and, that, is, was, to"
16778,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.125,"human, and, virus, the, was, in"
16779,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.125,"the, that, to, bats,, and"
16780,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.125,"was, in, the, closest, 96.2%"
16781,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.125,"to, and, bats,, is, that, in"
16782,"Bats have been reported as being the rich source of 

coronaviruses","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.125,"as, the, of"
16783,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.125,"sars-cov-2, to, the, for, of"
16784,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.125,"from, the, of, for, sars-cov-2"
16785,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.125,"of, sars-cov-2, to, the, plausible"
16786,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.125,"bats, the, hosts, for, of"
16787,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.125,"is, to, of, animal, the"
16788,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.125,"to, the, is, zoonotic, origin"
16789,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.125,"the, to, in, of, this, is"
16790,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.125,"the, is, that, of, covid-19, market, in"
16791,The COVID-19 most likely developed from bat origin coronaviruses,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.125,"the, covid-19, likely, origin"
16792,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.125,"in, a, to, wet, market"
16793,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.125,"in, china, seafood, market, were, a"
16794,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.125,"and, seafood, market, a, to"
16795,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.125,"animal, a, and, in, to"
16796,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.125,"the, of, to, animal, is"
16797,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.125,"sars-cov-2, an, animal, to, a, and"
16798,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.125,"a, and, an, animal"
16799,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.125,"is, the, of, a"
16800,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.125,"the, of, a, and, to"
16801,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.125,"coronavirus, to, is, sars-cov-2, the"
16802,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.125,"sars-cov-2, be, of, the, and, to, ability"
16803,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.125,"and, evolutionary, has, been, of"
16804,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.125,"bats, are, the, most, of"
16805,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.125,"of, the, has, been, are, by, that"
16806,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","All human coronaviruses have animal origins, namely, natu- 

ral hosts",0.125,"all, human, hosts"
16807,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.125,"hosts, natural, and, mers-cov, the"
16808,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.125,"the, of, may, be"
16809,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.125,"the, of, and"
16810,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.125,"the, and, reservoirs"
16811,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.125,"of, bats, and, the"
16812,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.125,"and, the, of, natural"
16813,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.125,"the, bats, and"
16814,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.125,"and, natural, of, the"
16815,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.125,"bats, and, are"
16816,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.125,"the, natural, hosts, and, mers-cov"
16817,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.125,"the, for, into, from, intermediate, animals"
16818,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.125,"that, the, virus, and, to, from, animals"
16819,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.125,"virus, that, to, the, and, for"
16820,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.125,"the, for, transmission, from, and"
16821,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.125,"the, sars-cov, outbreak, through"
16822,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.125,"the, of, with, early, sars-cov-2, at"
16823,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.125,"sequence, shares, with, of"
16824,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.125,"genomic, the, covid-19, through, of"
16825,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.125,"of, sars-cov-2, at, the, outbreak"
16826,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.125,"sars-cov-2, the, with, at, of"
16827,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.125,"in, the, highly, was, from, to, at"
16828,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.125,"in, the, was, to, at"
16829,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.125,"the, is, from, rhinolophus, in"
16830,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",Bats are likely reservoir hosts for SARS-CoV-2,0.125,"reservoir, bats"
16831,"According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",zoonotic origins of SARS-CoV-2 by natural evolution,0.125,"sars-cov-2, of"
16832,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",zoonotic origins of SARS-CoV-2 by natural evolution,0.125,"sars-cov-2, by, of"
16833,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",zoonotic origins of SARS-CoV-2 by natural evolution,0.125,"sars-cov-2, natural, zoonotic"
16834,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.125,"the, to, is, zoonotic, origin"
16835,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.125,"the, sars-cov-2, to, from, is"
16836,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.125,"sars-cov-2, a, origin, is"
16837,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.125,"sars-cov-2, the, origin, with"
16838,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.125,"the, of, including, and"
16839,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.125,"the, and, to, other"
16840,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.125,"diseases, to, of, the, which, and"
16841,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.125,"the, and, other, to"
16842,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.125,"the, of, and, species, into, humans,, barrier, to"
16843,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.125,"of, and, which, to, severe, humans,, respiratory"
16844,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.125,"other, the, to, and"
16845,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.125,"the, spread, and, in"
16846,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.125,"the, was, to, in, animals"
16847,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.125,"the, outbreak, sars-cov, through"
16848,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.125,"in, lineage, the, of, that, sars-cov-2"
16849,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.125,"analysis, in, the, protein, of, that"
16850,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.125,"in, the, that, of"
16851,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.125,"sars-cov-2, the, lineage, of"
16852,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.125,"bat, in, the, of"
16853,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.125,"the, of, with, and, that, sars-cov-2"
16854,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.125,"the, genome, that, sars-cov-2, and"
16855,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.125,"shares, with, that, of"
16856,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.125,"that, the, and, to, of"
16857,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.125,"the, that, of, natural"
16858,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.125,"the, that, are, of"
16859,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.125,"the, for, reservoirs, of"
16860,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.125,"the, that, of, for"
16861,"expended to make the simple point 

that COVID-19 had a natural origin.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.125,"the, that, natural"
16862,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.125,"of, natural, reservoirs, the"
16863,"Scientific reports published so far include  

hosts, such as bats (28), pangolins (29), cats  

(11), and dogs (30)","civet cats and raccoon dogs  

are the intermediate hosts",0.125,"cats, and, dogs"
16864,"Coronaviruses are naturally hosted and developmentally 

formed by bats.","civet cats and raccoon dogs  

are the intermediate hosts",0.125,"are, and"
16865,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","civet cats and raccoon dogs  

are the intermediate hosts",0.125,"the, and, intermediate"
16866,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.125,"highly, that, was, from, a, the, in, any"
16867,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.125,"highly, at, the, to, was, in, from"
16868,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.125,"and, that, from, the, coronavirus, was, at"
16869,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.125,"in, the, for, to, that, with, and, a"
16870,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.125,"to, from, a, in, the, and, that, with, coronaviruses"
16871,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.125,"are, a, coronaviruses, to, in, with, the, and"
16872,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.125,"the, at, time, that, a, in, for"
16873,Many of these CoVs can infect several animal species as well,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.125,"of, can, animal"
16874,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","with the first case being linked to  

a seafood market",0.125,"a, the, being, to, with"
16875,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","with the first case being linked to  

a seafood market",0.125,"the, a, to, market"
16876,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","with the first case being linked to  

a seafood market",0.125,"the, with, seafood, market, a"
16877,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","with the first case being linked to  

a seafood market",0.125,"the, to, a, with"
16878,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","with the first case being linked to  

a seafood market",0.125,"the, with, to"
16879,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.125,"the, of, to, in, is, this"
16880,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.125,"to, the, from, sars-cov-2, is"
16881,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.125,"sars-cov-2, been, from, to, identified, found, in"
16882,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.125,"the, to, sars-cov-2, in, from, of"
16883,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.125,"that, in, and, the"
16884,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.125,"a, in, the, that, originated"
16885,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.125,"was, that, the, a, it"
16886,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.125,"the, virus, was, a, that"
16887,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.125,"that, did, not, a, it"
16888,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.125,"sars-cov-2, to, a, an, animal, and"
16889,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.125,"identified, sars-cov-2, been, to, from, in, found"
16890,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.125,"a, and, likely, in, an, animal"
16891,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.125,"likely, are, species, in, and, south, china"
16892,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.125,"between, an, and, have, from, in, china"
16893,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.125,"similarity, to, a, from, bat, found, in"
16894,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.125,"bat, host, sars-cov-2, and, an, animal"
16895,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.125,"sars-cov-2, the, of, that, to, from"
16896,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.125,"the, to, that, origin"
16897,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.125,"the, of, that, a, natural"
16898,evidence suggests bats as its origin,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.125,"evidence, as, origin"
16899,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.125,"the, genomic, sars-cov-2, that, and"
16900,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.125,"studies, the, and, have, that, sars-cov-2"
16901,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.125,"that, the, sars-cov-2, studies, genomic"
16902,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.125,"the, coronavirus, was, that, from, at, and"
16903,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.125,"of, the, coronavirus, and, bat"
16904,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.125,"from, the, bat, and, nucleotide"
16905,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.125,"that, sars-cov-2, of"
16906,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.125,"that, sars-cov-2, before"
16907,"The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.125,"events, with, zoonotic"
16908,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.125,"the, to, bat, that, a"
16909,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.125,"the, sars-cov-2, of, to, that, bat"
16910,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.125,"that, the, of, sars-cov-2, at, two, a"
16911,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.125,"this, the, of, that, sars-cov-2, to"
16912,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.125,"a, of, viruses, to, the"
16913,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.125,"the, of, that, indicating, viruses"
16914,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.125,"that, are, the, a, of"
16915,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.125,"this, that, the, of, bat"
16916,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.125,"in, the, of, a, at, that, from, humans, were, both, and"
16917,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.125,"animals, from, intermediate, for, the, into"
16918,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.125,"the, from, at, market, for"
16919,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.125,"the, for, from, animals, most"
16920,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.125,"of, the, huanan, market, through"
16921,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.125,"the, market, to, late"
16922,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.125,"the, of, market, that, susceptible"
16923,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.125,"that, of, sars-cov-2, the, through"
16924,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.125,"be, transmission, to, of, and, are, sold"
16925,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.125,"that, be, sars-cov-2, are, animals"
16926,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.125,"of, the, and, that, sars-cov-2"
16927,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.125,"are, to, the, and, that, be"
16928,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.125,"sars-cov-2, at, the, early, of, with"
16929,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.125,"sars-cov-2, in, of, animal, and, that, the, with"
16930,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.125,"that, and, potential, sars-cov-2, humans, the, in, with"
16931,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.125,"early, cases, with, the, huanan, and, of, that, in, sars-cov-2, animal, at, market"
16932,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.125,"of, the, sars-cov-2, lineage, in, geographic, and"
16933,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.125,"a, study, in, the"
16934,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.125,"cases, in, the, huanan, market"
16935,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.125,"the, to, that, in"
16936,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.125,"cases, to, the, huanan, that"
16937,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.125,"the, in, to, that, we"
16938,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.125,"the, in, that, are, more"
16939,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.125,"that, are, the, more"
16940,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.125,"that, are, to, a, the"
16941,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.125,"the, at, origin, of"
16942,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.125,"the, market, with, late"
16943,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.125,"a, and, of, in, the, huanan"
16944,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.125,"a, at, market, in, the, is, of"
16945,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.125,"and, a, the, origin, of"
16946,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.125,"the, of, and, been, in"
16947,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.125,"the, human, animal, in, to"
16948,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.125,"the, animal, reservoirs, viruses"
16949,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.125,"the, to, closely, related, in"
16950,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.125,"the, more, than, to, in"
16951,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.125,"the, that, in, and, was"
16952,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.125,"genomic, that, sars-cov-2, and, the"
16953,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.125,"the, animal, in, market, and"
16954,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.125,"that, the, genomic, and, at"
16955,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.125,"that, genomic, the, sars-cov-2, in"
16956,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.125,"the, than, and, mers-cov, in"
16957,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.125,"that, sars-cov-2, in, animal"
16958,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.125,"the, that, sars-cov-2, at, and"
16959,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.125,"a, an, animal, and"
16960,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.125,"an, animal, a, likely, and, in"
16961,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.125,"from, in, humans, two, of, sars-cov-2, to"
16962,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.125,"a, zoonotic, spillover, from"
16963,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.125,"the, that, sars-cov-2, all, in"
16964,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.125,"a, that, the, sars-cov-2, in"
16965,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.125,"more, than, were, of, and"
16966,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.125,"the, and, that, of, were, to, huanan, half"
16967,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.125,"the, that, more, covid-19, than"
16968,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.125,"the, of, sars-cov-2, a, from, and"
16969,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.125,"the, presence, of, a, and, in"
16970,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.125,"animal, sars-cov-2, live, and, in, the"
16971,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor",0.125,"sars-cov-2, a, progenitor"
16972,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.125,"two, of, sars-cov-2, humans, from, in, to"
16973,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.125,"from, animals, in, the, may, have"
16974,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.125,"that, the, in, may, have, animals, a, of"
16975,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.125,"the, of, in, also, to, from"
16976,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.125,"the, of, spillover, sars-cov-2, to, a, in"
16977,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.125,"the, cases, one, of, a, spillover, to"
16978,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.125,"a, in, the, spillover, that, led, to"
16979,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.125,"had, its, such, as, it, to, this, for, by, the, of, that, been, a"
16980,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.125,"and, sars-cov-2, are, to, in, other, viruses"
16981,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.125,"is, that, sars-cov-2, was, from, laboratory, in, any"
16982,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.125,"to, sars-cov-2, is, that, from, and, was"
16983,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.125,"in, it, is, not, to, that, sars-cov-2, and"
16984,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.125,"it, was, in, other, and, are, to, sars-cov-2"
16985,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.125,"that, is, not, from, any, used"
16986,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.125,"be, virus, to, of, and, some, are, more, if, as, they"
16987,"Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.125,"a, sars-cov-2, progenitor"
16988,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.125,"that, is, a"
16989,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.125,"sars-cov-2, a, or"
16990,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.125,"to, a, wet, market, in"
16991,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.125,"a, it, genetic, the, in"
16992,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.125,"scientists, that, a, was, likely, the, of, is, we, to"
16993,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.125,"scientists, that, market, in, the, virus, was, first"
16994,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.125,"the, first, was, to, have, this, that, in, of"
16995,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.125,"spillover, that, an, animal"
16996,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.125,"that, is, in, to"
16997,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.125,"that, from, to, an, is, a, in"
16998,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.125,"in, an, to, that, humans."
16999,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.125,"in, to, an, animal"
17000,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.125,"a, from, in, wuhan, that, is, to"
17001,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.125,"a, of, scientists, to, the, we, likely, that, was, is"
17002,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.125,"but, to, is, of, the, and, was, naturally"
17003,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.125,"the, most, likely, to, of, sars-cov-2, and"
17004,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.125,"the, of, sars-cov-2, is, and, but"
17005,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.125,"the, of, samples, taken, market, that, at"
17006,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.125,"on, the, and, that, was, to"
17007,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.125,"that, the, virus, and, to, a"
17008,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.125,"and, a, to, the, coronavirus, with, as"
17009,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.125,"a, virus, that, bat"
17010,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.125,"has, a, similarity, to"
17011,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.125,"that, the, a, bat, coronavirus"
17012,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.125,"the, has, a, as, and"
17013,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.125,"is, also, that, from, the, virus"
17014,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.125,"is, and, from, animals"
17015,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.125,"the, is, also, from"
17016,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.125,"the, is, that, virus, and"
17017,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.125,"the, virus, is, that, and, this"
17018,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.125,"is, also, from, the"
17019,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.125,"the, and, huanan, seafood, is"
17020,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.125,"the, that, virus, animals, were"
17021,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.125,"this, that, the, and, is"
17022,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.125,"the, this, that, is, virus"
17023,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.125,"and, that, to, of, origin,"
17024,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.125,"have, of, to, a, and, species"
17025,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.125,"coronaviruses, to, that, all, and"
17026,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.125,"to, all, of, have, a"
17027,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.125,"coronaviruses, a, of, animals,"
17028,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.125,"have, that, in, and, from, animals"
17029,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.125,"origin, that, in, animals, and"
17030,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.125,"from, that, which, and, animals"
17031,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.125,"and, natural, host, of"
17032,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.125,"of, the, and, sars-cov,"
17033,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.125,"in, the, was, of"
17034,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.125,"considered, host, the, in"
17035,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.125,"from, and, animals, is"
17036,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.125,"a, to, bat, that, the"
17037,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.125,"the, to, bat, and"
17038,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.125,"that, was, first, and, a"
17039,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.125,"the, a, to, very"
17040,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.125,"the, very, to, that, was"
17041,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.125,"the, bat, coronavirus, to, sequence"
17042,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.125,"the, known, as, of, host"
17043,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.125,"the, was, to, of"
17044,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.125,"was, to, the, of"
17045,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.125,"possible, intermediate, host, the"
17046,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.125,"animal, as, was, the"
17047,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.125,"was, to, of, the"
17048,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.125,"with, the, in, of"
17049,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.125,"in, a, study, the"
17050,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.125,"a, of, the, with"
17051,"bats are also important reservoir species for a great 

range of coronaviruses","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.125,"bats, a, of"
17052,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.125,"a, of, in, the"
17053,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.125,"bats, the, a, of"
17054,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.125,"the, that, in, a, to, market"
17055,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.125,"the, of, and, were, in, with"
17056,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.125,"to, a, of, in, the, and, that, with"
17057,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.125,"the, of, that, to, a, with"
17058,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.125,"the, of, with, and, to"
17059,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.125,"the, of, indicates, that, a, in"
17060,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.125,"the, virus, which, to, that, of"
17061,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.125,"or, in, the, market, been"
17062,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.125,"the, that, virus, to, of, been"
17063,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.125,"the, of, or, to, virus, in"
17064,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.125,"the, that, virus, in, which, they"
17065,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.125,"through, the, huanan, market, of"
17066,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.125,"in, the, cases, huanan, market"
17067,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.125,"the, covid-19, in, market"
17068,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.125,"and, holmes, also, of, in, their, the, to"
17069,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.125,"that, was, sars-cov-2, to, from, and, is"
17070,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.125,"bats, to, be, the, intermediate"
17071,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.125,"a, the, that, was, to"
17072,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.125,"is, that, the, be, and, sars-cov-2"
17073,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.125,"to, that, the, bats, and, as, sars-cov-2"
17074,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.125,"was, to, that, sars-cov-2, the"
17075,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.125,"of, covid-19, which, has, for, to, a, virus, that, and, the"
17076,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.125,"that, the, for, to, a, bat"
17077,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","Bats have been reported as being the rich source of 

coronaviruses",0.125,"the, of, as"
17078,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Bats have been reported as being the rich source of 

coronaviruses",0.125,"the, been, have"
17079,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","Bats have been reported as being the rich source of 

coronaviruses",0.125,"have, been, bats"
17080,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Bats have been reported as being the rich source of 

coronaviruses",0.125,"the, bats, as, of"
17081,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Bats have been reported as being the rich source of 

coronaviruses",0.125,"the, of, been, bats"
17082,"Bats have been reported as being the rich source of 

coronaviruses","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.125,"have, been, the"
17083,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.125,"a, sars-cov-2, pangolin"
17084,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.125,"the, to, sars-cov-2, similarity"
17085,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.125,"the, from, with, a, sars-cov-2"
17086,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.125,"the, sars-cov-2, have, been, from"
17087,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.125,"the, sars-cov-2, to, a"
17088,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.125,"to, sars-cov-2, has, similarity, the"
17089,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.125,"with, the, pangolin, have, to"
17090,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.125,"and, sars-cov-2, to, humans, pangolins, the, with"
17091,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.125,"the, of, sars-cov-2, to, humans, and"
17092,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.125,"the, of, and, similar, to"
17093,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.125,"the, sars-cov-2, their, and, of"
17094,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.125,"the, sars-cov-2, bat, identity"
17095,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.125,"with, bat, the"
17096,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.125,"the, has, identity, bat"
17097,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.125,"bat, the, sars-cov-2, with, ratg13"
17098,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.125,"the, sars-cov-2, has, with"
17099,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.125,"the, identity, sars-cov-2, from"
17100,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.125,"sars-cov-2, the, genetic, of, that, to"
17101,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.125,"that, of, to, a, sars-cov-2, analysis, the"
17102,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.125,"a, by, that, the, virus, to, of"
17103,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.125,"the, and, has, a, to, that, of"
17104,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.125,"and, the, of"
17105,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.125,"is, and, of, the"
17106,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.125,"of, to, the, and"
17107,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.125,"pangolin, and, to"
17108,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.125,"to, the, and, of"
17109,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.125,"of, and, to, the"
17110,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.125,"is, of, the"
17111,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.125,"is, the, of"
17112,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.125,"is, the, to, that, and, was"
17113,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.125,"studies, that, sars-cov-2, have, and, the"
17114,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.125,"on, the, was, that, and, to"
17115,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.125,"the, have, an, animal, to, and"
17116,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.125,"the, sequences, conserved, to, that, of"
17117,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.125,"studies, have, the, of, to, and, which"
17118,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.125,"sars-cov-2, the, and, that, of, based, is"
17119,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.125,"is, to, the, that, by, an, and"
17120,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.125,"studies, that, sars-cov-2, is, to"
17121,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.125,"virus, to, in, its"
17122,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.125,"in, the, its, a, bats"
17123,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.125,"to, virus, and, was, the"
17124,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.125,"in, the, was, a, virus, from, to, and"
17125,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.125,"a, virus, the, in, its"
17126,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.125,"the, to, and, in, bats"
17127,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.125,"animals, from, that, virus, to, and, the"
17128,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.125,"the, virus, a, that, and, to"
17129,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.125,"that, have, in, animals, and, from"
17130,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.125,"the, to, that, in, china, and"
17131,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.125,"the, genetic, to, and, in, bats"
17132,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.125,"the, that, at, virus, and, to"
17133,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.125,"that, the, covid-19, to, of"
17134,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.125,"that, the, may, of"
17135,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.125,"to, the, of, may, most"
17136,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.125,"that, the, of, to, covid-19"
17137,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.125,"and, in, to, bats, of, which"
17138,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.125,"the, which, to, of, and, diseases"
17139,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.125,"naturally, was, the, of, and, is, but, to"
17140,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.125,"the, of, and, are, to, is"
17141,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.125,"the, was, to, has, in, of, animals"
17142,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.125,"to, has, the, virus, but, bats, of"
17143,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.125,"in, genetic, to"
17144,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.125,"genetic, that, been, used, to"
17145,hese close genetic relations suggest that they all have their ecological origin in bat populations,"genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.125,"genetic, that, in"
17146,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.125,"that, in, to"
17147,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.125,"is, a, of, the"
17148,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.125,"of, the, a, at"
17149,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.125,"the, is, that, of, all, at"
17150,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.125,"virus, more, to, in"
17151,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.125,"that, origin, in, animals, and"
17152,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.125,"the, more, to, and, in"
17153,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.125,"and, in, to, the, natural, origin"
17154,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.125,"and, is, virus, that"
17155,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.125,"and, the, reservoirs"
17156,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.125,"to, the, that, origin"
17157,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.125,"the, that, to, and"
17158,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.125,"in, that, the, to"
17159,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.125,"animal, and, the, is"
17160,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.125,"the, that, sars-cov, and"
17161,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.125,"the, that, virus, in, animal"
17162,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.125,"to, the, its, in"
17163,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.125,"that, is, the"
17164,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.125,"in, that, the, and"
17165,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.125,"the, in, seafood, wuhan,"
17166,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.125,"the, bat, with"
17167,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.125,"the, bat, sars-like, and"
17168,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.125,"the, sequence, of, that, to, and"
17169,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.125,"t, be, that, to"
17170,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.125,"be, of, the, and, zoonotic, to, virus"
17171,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.125,"the, sars-cov, and, mers-cov, is, to"
17172,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.125,"the, and, for, to, host, is, sars-cov"
17173,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.125,"it, the, with, coro-, navirus, as, a, of"
17174,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.125,"of, the, sequence, and, with, bat, identity"
17175,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.125,"the, natural, of, as, a, and"
17176,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.125,"sequence, identity, with, bat, and, human, a"
17177,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.125,"the, of, is, with, and, sars-cov"
17178,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.125,"the, bats, reservoir, of"
17179,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.125,"the, could, or, infected"
17180,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.125,"from, in, the, animals, may, have"
17181,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.125,"the, market, in, been, or"
17182,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.125,"have, the, market, in"
17183,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.125,"and, an, with, to, at, the, huanan, seafood, market, of, january, 1,, on, a, was"
17184,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.125,"the, in, and, spread"
17185,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.125,"the, and, were, in"
17186,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.125,"the, sars-cov-2, to, be, is, possible"
17187,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.125,"bat, is, the, sars-cov-2, that, bats"
17188,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.125,"to, that, sars-cov-2, the, bats, be"
17189,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.125,"in, scientists, the, virus, that, was, first, market"
17190,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.125,"were, a, seafood, market, in, china"
17191,"with the first case being linked to  

a seafood market","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.125,"with, the, a, seafood, market"
17192,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.125,"in, the, of, that, a, animals, may, have"
17193,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.125,"a, the, as, of, coro-, navirus, it, with"
17194,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.125,"have, the, seafood, market, in, wuhan"
17195,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.125,"were, a, it, with, the, in"
17196,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.125,"the, for, from, at, market"
17197,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.125,"a, of, the, with, that, novel"
17198,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.125,"bat, to, the, of"
17199,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.125,"sars-cov-2, bat, cov), to, the"
17200,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.125,"genome, the, bat, of, reported"
17201,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.125,"the, of, identical, to, sars-cov-2"
17202,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.125,"the, to, of, sars-cov-2"
17203,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.125,"the, group, of, to"
17204,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.125,"to, the, and, is, host, for, sars-cov"
17205,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.125,"receptor, and, that, sars-cov, is, by"
17206,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.125,"study,, ace2, to, sars-cov-2, and, the"
17207,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.125,"the, to, that, sars-cov-2, was, also"
17208,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.125,"a, by, was, that, the, is, to, previously"
17209,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.125,"a, that, the, to, which, and"
17210,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.125,"is, more, than, to, genome"
17211,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.125,"to, the, of, be, human, bat"
17212,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.125,"to, the, s, can, human, for"
17213,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.125,"the, of, to, bat, is, for"
17214,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.125,"to, the, and, bats, or, could, be, for"
17215,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.125,"of, analysis, that, the, bat, covs, and"
17216,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.125,"that, the, similarity, sars-cov-2, and, bat, cov"
17217,"civet cats and raccoon dogs  

are the intermediate hosts","Coronaviruses are naturally hosted and developmentally 

formed by bats.",0.125,"and, are"
17218,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.125,"the, of, that, bat"
17219,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.125,"that, bat, has, of"
17220,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.125,"it, has, been, the, are, that"
17221,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.125,"bat, have, genetic, to, and"
17222,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.125,"sars-cov-2, the, genetic, of, that, have, to"
17223,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.125,"the, genome, of, and, bat, that, sequence, to"
17224,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.125,"of, to, sars-cov-2, and, the, several"
17225,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.125,"the, sequence, et, al.,, of, sars-cov-2"
17226,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.125,"that, the, beta, to, and, sars-cov-2"
17227,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.125,"et, genome, that, the, virus, is, to, of"
17228,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.125,"sars-cov-2, may, that"
17229,"This suggests that the BANAL series may be able to directly infect  

humans.","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.125,"that, may, to"
17230,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.125,"in, the, of, as, a"
17231,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.125,"a, the, of, isolated, from, in"
17232,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.125,"the, of, in, viruses"
17233,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.125,"as, the, viruses, of"
17234,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.125,"are, a, of, viruses"
17235,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.125,"genetic, bats, of, by, and"
17236,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.125,"sars-cov, and, is, bat, of"
17237,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.125,"that, receptor, and, is, by, sars-cov"
17238,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.125,"that, recombination, and, of, bat"
17239,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.125,"that, is, most, of"
17240,COVID-19 is a zoonotic virus,The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.125,"covid-19, virus"
17241,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.125,"the, covid-19, virus, has"
17242,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.125,"the, in, has"
17243,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.125,"bats, virus, the, ecological"
17244,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.125,"virus, the, in, its"
17245,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.125,"the, bats, reservoir, its"
17246,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.125,"the, covid-19, which, most"
17247,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",Many of these CoVs can infect several animal species as well,0.125,"animal, of, can"
17248,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",Many of these CoVs can infect several animal species as well,0.125,"of, animal, these, species, as"
17249,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",Many of these CoVs can infect several animal species as well,0.125,"several, species, of"
17250,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.125,"is, that, a"
17251,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.125,"virus, a, that, to"
17252,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.125,"an, a, that, virus, from, to, human"
17253,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.125,"to, a, from, is"
17254,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.125,"is, to, that, from, an"
17255,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.125,"to, that, transmitted, from"
17256,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.125,"from, humans, to, the"
17257,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.125,"a, for, it, the"
17258,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.125,"to, sars-cov-2, from, bats, the"
17259,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.125,"from, to, humans, the"
17260,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.125,"sars-cov-2, the, humans, from"
17261,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.125,"to, date, sars-cov-2, from, bats, the, coronaviruses"
17262,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.125,"the, sars-cov-2, to, closely, related"
17263,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.125,"closely, related, are, to, sars-cov-2, the"
17264,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.125,"the, sars-cov-2, are, to, bat"
17265,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.125,"bats, of, to, the"
17266,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.125,"bats, also, the, of, is, in, to"
17267,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.125,"from, in, also, the, of, to"
17268,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.125,"from, the, also, is"
17269,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.125,"bats, to, the, of"
17270,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.125,"in, the, to, of"
17271,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.125,"to, bats, the, of"
17272,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.125,"to, in, the, of"
17273,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.125,"closely, related, to, the, is"
17274,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.125,"coronaviruses, to, in, the, is, of"
17275,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.125,"in, the, of, is, to"
17276,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.125,"in, to, of, the"
17277,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.125,"are, and, the, in"
17278,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.125,"found, in, rhinolophus, the"
17279,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.125,"human, in, to, the, animal"
17280,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.125,"the, animal, market, in, and"
17281,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.125,"the, and, have, an, animal, to"
17282,"Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.125,"or, the, infected, could"
17283,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.125,"may, from, virus, in"
17284,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.125,"in, to, the, from, and, an"
17285,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.125,"a, sars-cov-2, is, origin"
17286,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.125,"a, that, is, and"
17287,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.125,"that, all, sars-cov-2, a, and"
17288,Bats are likely reservoir hosts for SARS-CoV-2,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.125,"bats, reservoir"
17289,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.125,"and, species, the, animal"
17290,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.125,"sars-cov-2, from, humans, the"
17291,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.125,"the, is, from, species"
17292,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.125,"is, sars-cov-2, and, the, that"
17293,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.125,"that, of, sars-cov-2, is, to, it"
17294,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.125,"sars-cov-2, is, between, and, species, be, to, that"
17295,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.125,"there, is, that, of, to, sars-cov-2"
17296,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.125,"and, of, to, it, be, that, sars-cov-2, is"
17297,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.125,"of, to, it, is, likely, that"
17298,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.125,"that, sars-cov-2, to, it, an, intermediate"
17299,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.125,"that, sars-cov-2, animal, species, humans"
17300,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.125,"the, of, coronavirus, that, to, and"
17301,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.125,"the, that, to, and, coronavirus"
17302,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.125,"virus, genome, and, bat, of"
17303,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.125,"the, of, bat, and, sequence, identity, with"
17304,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.125,"of, the, sequence, coronavirus, genomes"
17305,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.125,"was, and, the, of, betacoronavirus"
17306,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.125,"genome, the, bat, of, virus, and"
17307,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.125,"the, of, showed, identity, with"
17308,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.125,"the, in, human, virus, and, was"
17309,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.125,"and, with, the, of, virus, isolated, in"
17310,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.125,"with, the, of, sequencing, genome, from, and"
17311,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.125,"analysis, showed, the, of, genome, covid-19"
17312,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.125,"analysis, of, covid-19, virus, the, and"
17313,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.125,"virus, isolated, from, in, with, the, of"
17314,The virus which causes COVID-19 most probably has its ecological reservoir in bats,COVID-19 is a zoonotic virus,0.125,"virus, covid-19"
17315,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",COVID-19 is a zoonotic virus,0.125,"zoonotic, is, a"
17316,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",COVID-19 is a zoonotic virus,0.125,"covid-19, virus, is"
17317,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.125,"to, be, of, the"
17318,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.125,"of, the, covid-19, to, with"
17319,The COVID-19 most likely developed from bat origin coronaviruses,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.125,"the, covid-19, from"
17320,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.125,"the, zoonotic, and, in"
17321,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.125,"and, are, to, coronaviruses, viruses"
17322,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.125,"and, to, the, zoonotic"
17323,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.125,"the, as, a, coronavirus, with, and, to"
17324,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.125,"as, to, the, of, be, a, human"
17325,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.125,"bats, as, the, reservoirs, of, and"
17326,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.125,"is, highly, that, sars-cov-2, the, sequence"
17327,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.125,"the, of, coronaviruses, that, to"
17328,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.125,"of, the, sequence, genomes, coronavirus"
17329,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.125,"the, is, that, to, of"
17330,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.125,"the, of, is, to, that, sars-cov-2"
17331,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.125,"is, highly, that, sars-cov-2, the, of"
17332,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.125,"to, that, the, of, is"
17333,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.125,"of, sars-cov-2, is, the, genomes, to"
17334,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.125,"the, and, of, bat, human"
17335,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.125,"and, the, bat, coronavirus, of"
17336,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.125,"the, of, sars-cov,, and"
17337,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.125,"the, of, has, with, human, and"
17338,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.125,"the, of, and, identity, with"
17339,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.125,"the, of, with, and"
17340,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.125,"that, the, and, of, sequence, to"
17341,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.125,"that, the, of, coronavirus, and, to"
17342,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.125,"related, bat, coronavirus, to, as, the, genome"
17343,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.125,"the, from, that, to, bat, and, coronavirus"
17344,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.125,"of, to, genome, sequence, was, from, bat"
17345,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.125,"origin,, that, of, to, and"
17346,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.125,"the, bat, has, identity"
17347,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.125,"the, of, covid-19, to, that"
17348,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.125,"the, virus, covid-19, has"
17349,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.125,"that, the, of, bat, covid-19"
17350,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.125,"the, has, of, that, to, bat, and"
17351,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.125,"in, with, amino, acid, of"
17352,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.125,"analysis, the, that, and, sars-cov-2"
17353,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.125,"sars-cov-2, not, that, the, a"
17354,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.125,"ace2, receptor, sars-cov-2"
17355,"zoonotic corona- 

viruses have become an increasing threat to human health,","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.125,"zoonotic, to, human"
17356,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.125,"host, sars-cov-2, to, or"
17357,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.125,"in, sars-cov-2, animal, human, or"
17358,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.125,"the, genomic, at, that, and"
17359,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.125,"the, is, and, animal"
17360,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.125,"the, disease, is, and"
17361,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.125,"first, and, that, was, a"
17362,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.125,"in, seafood, market, china"
17363,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.125,"the, of, conserved, sequences, that, to"
17364,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.125,"amino, acid, within, the, to"
17365,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.125,"that, are, identical, to"
17366,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.125,"the, to, are, identical"
17367,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.125,"the, amino, acid, of, to"
17368,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.125,"the, between, sars-cov-2, and, a, of, in, bat"
17369,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.125,"the, virus, in, and, from, a, china"
17370,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.125,"and, virus, with, the, isolated, in, of"
17371,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.125,"with, the, of, a, genome, from, and"
17372,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.125,"sars-cov-2, has, a, genome, sars-cov"
17373,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.125,"of, and, bat, a, between, in, the"
17374,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.125,"of, virus, revealed, the, bat, and"
17375,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.125,"virus, a, that, bat"
17376,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.125,"that, may, sars-cov-2"
17377,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.125,"virus, from, in, may"
17378,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.125,"that, may, a"
17379,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.125,"that, sars-cov-2, bat, in"
17380,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.125,"that, sars-cov-2, in"
17381,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.125,"in, a, sars-cov-2, that, may"
17382,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.125,"the, analysis, that, protein, in, of"
17383,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.125,"a, the, of, with"
17384,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.125,"the, and, sars-cov, that"
17385,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.125,"a, of, the, novel, with, that"
17386,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.125,"the, genome, of, sars-cov, and, that, a"
17387,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.125,"that, of, a, with, sars-cov-2, analysis, the"
17388,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.125,"a, that, the, and, sars-cov-2"
17389,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.125,"the, presence, of, that, sars-cov-2"
17390,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.125,"and, that, a, of, the"
17391,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.125,"the, and, sequences, are, similar, to, sars-cov"
17392,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.125,"a, of, the, genome, that, sars-cov, and"
17393,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.125,"in, the, of, sequence, that, to, ratg13, similar"
17394,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.125,"similar, sequences, of, and, sars-cov, bat, ratg13"
17395,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.125,"that, are, the, a, of, sars-cov, and"
17396,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.125,"and, bat, ratg13, coronaviruses, to, the, of"
17397,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.125,"sars-cov-2, and, are, the"
17398,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.125,"sars-cov-2, animal, humans"
17399,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.125,"the, sars-cov-2, of, and"
17400,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.125,"bats, are, the, of, most"
17401,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.125,"to, be, bats, the, intermediate"
17402,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.125,"the, most, to, be"
17403,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.125,"the, of, are, likely, to"
17404,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Bats are natural hosts of many of the known  

coronaviruses",0.125,"the, are, of, bats"
17405,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Bats are natural hosts of many of the known  

coronaviruses",0.125,"the, many, of, known, are"
17406,The COVID-19 most likely developed from bat origin coronaviruses,"Bats are natural hosts of many of the known  

coronaviruses",0.125,"the, coronaviruses"
17407,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.125,"is, between, and, that, sars-cov-2, to, species, be"
17408,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.125,"n, that, sars-cov-2, may, in, bats"
17409,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.125,"and, from, in, to, be, that, coronavirus, is, bats, sars-cov-2"
17410,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.125,"a, at, two, that, the, of, sars-cov-2"
17411,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.125,"that, the, similarity, sars-cov-2, and, which, share"
17412,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.125,"is, the, to, considered"
17413,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.125,"to, the, be, most"
17414,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.125,"the, to, is, likely"
17415,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.125,"identified, coronavirus, from, which"
17416,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.125,"which, from, a, with, sars-cov-2"
17417,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.125,"the, sars-cov-2, has, with, similarity"
17418,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.125,"virus, and, has, been, of"
17419,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.125,"a, the, of, is, virus, and, that, to"
17420,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.125,"of, to, the, that, been, virus"
17421,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.125,"at, the, to, was, in"
17422,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.125,"the, to, that, of, coronavirus"
17423,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.125,"to, a, that, was, the"
17424,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.125,"the, that, to, a, of"
17425,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.125,"the, of, in, with, genome"
17426,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.125,"to, in, at, the"
17427,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.125,"to, a, of, in, the, that, with"
17428,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.125,"that, a, the, of, at, genome"
17429,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.125,"the, of, to, a, in"
17430,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.125,"the, that, sars-, cov-2"
17431,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.125,"pangolin, to, and"
17432,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.125,"be, that, a, of"
17433,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.125,"may, the, of, that"
17434,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.125,"may, a, that"
17435,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.125,"the, sars-cov-2, with, of"
17436,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.125,"chinese, and, an, with, hubei, at, the, huanan, seafood, in, of, on"
17437,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.125,"on, patients, in, the, of, these, and, reported"
17438,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.125,"that, the, cases, to, huanan"
17439,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.125,"the, to, be, seafood"
17440,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.125,"a, the, that, of"
17441,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.125,"a, of, the, that, scientific, data"
17442,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.125,"the, that, of, sars-cov-2, is, hypothesis"
17443,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.125,"in, the, market, have"
17444,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.125,"the, wuhan, in, have, seafood, market"
17445,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.125,"is, to, have, in, the"
17446,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.125,"the, sars-cov-2, lineage, of"
17447,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.125,"of, the, and, betacoronavirus, was"
17448,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.125,"the, of, sars-cov-2, to, cov"
17449,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.125,"the, sars-cov-2, to, from, in, of"
17450,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.125,"sars-cov-2, from, an, to, a, in, bat"
17451,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.125,"the, from, sars-cov-2, to, a, bat"
17452,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.125,"bat, the, of, sars-cov-2, an"
17453,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.125,"the, also, in"
17454,"Bats have been reported as being the rich source of 

coronaviruses","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.125,"bats, have, been"
17455,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.125,"viruses, closely, related, sars-cov-2"
17456,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.125,"viruses, sars-cov-2, have, been, in"
17457,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.125,"origin, of, at, the"
17458,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.125,"that, spillover, an, animal"
17459,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.125,"that, the, reservoir, of"
17460,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.125,"a, pangolin, sars-cov-2"
17461,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.125,"sars-cov-2, ace2, receptor"
17462,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.125,"a, between, and"
17463,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.125,"of, the, that, and, part"
17464,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.125,"in, a, of, and, that, the, for"
17465,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.125,"even, the, was, that, in, of"
17466,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.125,"in, such, coronaviruses, have"
17467,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.125,"of, other, coronaviruses, such, as"
17468,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.125,"of, the, in, viruses"
17469,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.125,"the, has, in"
17470,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.125,"the, natural, for, of"
17471,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.125,"the, natural, of, viruses, in, for"
17472,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.125,"the, of, natural, has"
17473,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.125,"the, from, and, a, of, sars-cov-2"
17474,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.125,"a, the, as, natural, of, and"
17475,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.125,"pangolins, a, sars-cov-2, the"
17476,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.125,"sars-cov-2, and, ratg13, the, between"
17477,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.125,"r., of, sars-cov-2, the"
17478,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.125,"the, of, that, sequence, in, ratg13, similar, to"
17479,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.125,"that, the, sars-cov-2, ratg13, pangolin, which"
17480,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","this one jumped from bats origin  

into humans",0.125,"from, humans, bats"
17481,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.125,"the, and, which, have, to, a, of, human"
17482,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.125,"have, a, species, of, to, and"
17483,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.125,"studies, the, of, and, have, which, to"
17484,The virus which causes COVID-19 most probably has its ecological reservoir in bats,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.125,"the, virus, ecological, bats"
17485,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.125,"bats, are, the, of, coronaviruses"
17486,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K",0.125,"in, more, than, to, with, human"
17487,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.125,"the, been, of, and, zoonotic"
17488,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.125,"and, in, been, the, of"
17489,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.125,"in, the, and, a, presence, of"
17490,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.125,"the, of, in, a, and"
17491,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.125,"in, the, bat, of, and"
17492,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.125,"detected, in, of, the"
17493,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.125,"to, the, of, sars-cov-2, for"
17494,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.125,"of, the, reservoirs, for"
17495,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.125,"viruses, to, the, of, sars-cov-2"
17496,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.125,"the, genome, of, a, it, shares"
17497,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.125,"the, of, its, as, a, bats"
17498,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.125,"genome, sequencing, of, the, from, with, and"
17499,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.125,"genome, a, and, with, the, of, from"
17500,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.125,"to, sars-cov-2, genome"
17501,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.125,"sars-cov-2, or, a"
17502,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.125,"a, has, similarity, to"
17503,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.125,"genome, has, a, sars-cov-2, sars-cov"
17504,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.125,"a, the, in, it, with, sars-cov-2"
17505,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.125,"sars-cov-2, a, because, the, genetic, in"
17506,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.125,"genetic, the, in, a, it"
17507,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.125,"in, the, considered, host"
17508,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.125,"the, possible, intermediate, host"
17509,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.125,"it, the, with, in, were, a"
17510,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.125,"a, for, the, it"
17511,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.125,"the, sars-cov-2, a, pangolins"
17512,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.125,"sars-cov-2, were, in, the"
17513,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.125,"it, in, a, with, sars-cov-2, the"
17514,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.125,"a, similarity, sars-cov-2, in, the, for"
17515,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.125,"the, sars-cov-2, a, with, cov"
17516,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.125,"for, in, the, sars-cov-2"
17517,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.125,"the, sars-cov-2, a, in, for"
17518,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.125,"the, to, be, a, of, bat, human"
17519,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.125,"the, of, to, human, bat, be"
17520,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.125,"a, to, the, be, of, human, as"
17521,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.125,"the, to, be, most"
17522,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.125,"the, of, most, a, bat"
17523,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.125,"the, as, a, of, most, to, bat"
17524,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.125,"the, of, a, human, as"
17525,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.125,"the, of, that, sars-cov-2, is, to"
17526,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.125,"there, is, that, of, sars-cov-2, to"
17527,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.125,"sars-cov-2, viruses, that, to"
17528,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.125,"to, of, is, that, similar, viruses"
17529,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.125,"sars-cov-2, to, highly, genome, the"
17530,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.125,"the, and, sars-cov-2, was, to, by"
17531,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.125,"the, by, was, and, to, december"
17532,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.125,"in, the, a, that, to, and, with, for"
17533,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.125,"that, not, it, sars-cov-2, to, and, is, in"
17534,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.125,"that, the, and, this, virus, is"
17535,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.125,"of, the, has, and, with, human"
17536,"In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.125,"in, to, with, more, than, human"
17537,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.125,"and, to, in, the, evolution, of"
17538,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.125,"in, it, is, that, the, and, sars-cov-2"
17539,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.125,"the, that, with, of, sars-cov-2, is, it, for"
17540,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.125,"that, is, in, from, a, an, to"
17541,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.125,"a, analysis, of, to, that, sars-cov-2, the"
17542,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.125,"a, analysis, of, the, sars-cov-2, with, that"
17543,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.125,"from, a, is, to, in, the, suggests, that"
17544,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.125,"the, of, were, in, with, and"
17545,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.125,"in, the, with, genome, of"
17546,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.125,"the, from, rhinolophus, collected, in"
17547,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.125,"the, of, sars-cov-2, identity, with"
17548,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.125,"has, that, of, bat"
17549,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.125,"in, a, of, with"
17550,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.125,"that, a, of, virus, with, sars-cov-2"
17551,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.125,"to, that, the, sars-cov-2"
17552,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.125,"that, the, to, sars-cov-2"
17553,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.125,"that, the, sars-cov-2, is"
17554,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.125,"that, the, sars-cov-2"
17555,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.125,"late, the, market, to"
17556,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.125,"with, the, market, late"
17557,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.125,"the, to, market"
17558,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.125,"has, been, that, animal"
17559,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.125,"the, analysis, that, sars-cov-2, and"
17560,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.125,"the, and, that, part, of"
17561,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.125,"analysis, that, the, and, of"
17562,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.125,"that, of, ratg13,, and, the, sars-cov-2"
17563,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.125,"that, sars-cov-2, and, pangolin-cov"
17564,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.125,"sars-cov-2, has, the, ratg13"
17565,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.125,"sars-cov-2, from, to, evolved, in, an"
17566,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","bats are also important reservoir species for a great 

range of coronaviruses",0.125,"a, of, bats"
17567,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","bats are also important reservoir species for a great 

range of coronaviruses",0.125,"a, great, of, bats"
17568,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","bats are also important reservoir species for a great 

range of coronaviruses",0.125,"are, also, a, of"
17569,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.125,"the, of, to, humans, and, sars-cov-2"
17570,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.125,"study,, the, sars-cov-2, ace2, and, to"
17571,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.125,"several, the, sars-cov-2, and, of, to"
17572,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.125,"from, the, of, in, sars-cov-2"
17573,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.125,"in, the, and, an, of"
17574,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.125,"nucleotide, and, from, the, bat"
17575,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.125,"from, sars-cov-, 2, the"
17576,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.125,"sequence, with, bat, ratg13,, and"
17577,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.125,"sars-cov-, 2, nucleotide, and"
17578,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.125,"with, the, sars-cov-2, of, sequence"
17579,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.125,"the, sars-cov-2, of, et, al.,, sequence"
17580,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.125,"the, amino, acid, sequence, of"
17581,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.125,"rbd, of, sars-cov-2, which, the"
17582,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.125,"of, shares, sequence, with"
17583,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.125,"of, shares, with, that"
17584,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.125,"that, with, s, protein, of"
17585,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.125,"the, be, amino, acid, sequence, in"
17586,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.125,"t, that, be, to"
17587,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.125,"cleavage, furin, to, that, can, naturally"
17588,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.125,"the, amino, acid, to, a, in, human"
17589,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.125,"s, the, to, human, for, can"
17590,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.125,"is, and, it, that, of, sars-cov-2, to, be"
17591,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.125,"of, that, it, is, to, the, and"
17592,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.125,"the, of, animal, with, and, that, sars-cov-2, in"
17593,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.125,"the, in, and, that, for, a, of"
17594,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.125,"and, the, therefore, that, or, for, of, sars-cov-2, in, a"
17595,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.125,"that, the, in, and, intermediate, hosts, of"
17596,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.125,"the, in, that, as, animal, for"
17597,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.125,"the, potential, with, and, that, sars-cov-2, humans, in"
17598,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.125,"pangolins, to, humans, and, with, the, sars-cov-2"
17599,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.125,"the, for, and, other, to, in"
17600,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.125,"transmission, to, humans, other, be, with, and, in"
17601,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.125,"suggest, that, may, to, sars-cov-2, in, humans"
17602,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.125,"it, has, been, that, the, are"
17603,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.125,"and, it, to, the, that, may, have, been, in, infect"
17604,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.125,"that, may, have, been, to, and, are, the"
17605,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.125,"the, to, changes, that, and, sars-cov-2"
17606,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.125,"to, the, that, sars-cov-2, a"
17607,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.125,"the, that, to, sars-cov-2, and"
17608,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.125,"the, sars-cov-2, and, beta, to, that"
17609,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.125,"a, the, sars-cov-2, that, and"
17610,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.125,"in, the, that, sars-cov-2, was, to"
17611,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.125,"sars-cov-2, was, to, the, in"
17612,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.125,"the, amino, acid, within, to"
17613,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.125,"to, humans, and, the, of, sars-cov-2"
17614,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.125,"sars-cov-2, is, to, be, the, possible"
17615,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.125,"the, species, to, of, sars-cov-2, and"
17616,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.125,"the, and, to, humans, through, of"
17617,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.125,"and, be, to, humans, through"
17618,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.125,"sars-cov-2, be, between, the, and"
17619,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.125,"a, from, zoonotic, spillover"
17620,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.125,"the, to, a, very"
17621,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.125,"with, to, the, of, covid-19"
17622,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.125,"in, the, live, animal, and, sars-cov-2"
17623,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.125,"in, the, to, at"
17624,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.125,"to, at, the, in"
17625,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.125,"were, sars-cov-2, the, in"
17626,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.125,"in, the, to, sars-cov-2, at"
17627,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.125,"the, market, that, susceptible, of"
17628,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.125,"the, of, at, market, samples, taken, that"
17629,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.125,"this, in, the, of, that, was"
17630,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.125,"in, this, that, the, of"
17631,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.125,"sars-cov-2, bat, similarity, to"
17632,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.125,"the, of, sars-cov-2, from, for"
17633,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.125,"that, the, of, sars-cov-2, from"
17634,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.125,"in, from, of, sars-cov-2, the"
17635,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.125,"positive, samples, of, in, the, western"
17636,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.125,"bats, a, the, recombination, of, and, in, with, that, to"
17637,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.125,"in, the, a, that, coronaviruses, from, to, and, with"
17638,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.125,"sars-cov-2, from, to, date, coronaviruses, bats, the"
17639,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.125,"the, furin, cleavage, site, of, and, sars-cov-2"
17640,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.125,"bats, the, for, of"
17641,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.125,"the, of, bats, reservoir, for"
17642,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.125,"including, the, coronaviruses, do, not, of"
17643,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.125,"coronaviruses, are, of, including"
17644,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.125,"of, the, that, sars-cov-2, is, highly"
17645,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.125,"a, the, genome, that, of, at"
17646,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.125,"sars-cov-2, is, a, virus, that, the, pandemic"
17647,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.125,"the, of, is, sars-cov-2, at, that, virus"
17648,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.125,"in, the, of, a, sars-cov-2, to, spillover"
17649,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.125,"of, to, the, in, virus, or"
17650,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.125,"closely, related, to, a, the, is"
17651,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.125,"are, likely, and, in, species, china, south"
17652,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.125,"of, coronaviruses, including, sars-cov-2"
17653,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.125,"viruses, the, animal, reservoirs"
17654,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.125,"the, animal, and, reservoirs"
17655,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.125,"of, the, as, viruses"
17656,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.125,"and, the, bats, reservoirs, of, as"
17657,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.125,"of, the, and, for"
17658,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.125,"bats, the, of, and, viruses, for"
17659,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.125,"the, for, and"
17660,"An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.125,"reservoir, of, bat, species"
17661,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.125,"most, likely, the, of, sars-cov-2, and, to"
17662,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.125,"the, of, sars-cov-2, to, species, and"
17663,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.125,"the, coronaviruses, and, southeast, asia,, most"
17664,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.125,"the, sars-cov-2, and, to, in, bat, coronaviruses"
17665,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.125,"that, sars-cov-2, to, bat, the"
17666,"All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.125,"all, the, that, in, sars-cov-2"
17667,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.125,"all, coronaviruses, that, to, and"
17668,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.125,"that, the, in, and, to, china"
17669,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.125,"sars-cov-2, that, in, bat"
17670,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.125,"in, the, and, to, that, sars-cov-2, bat, are"
17671,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.125,"the, and, in, were"
17672,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.125,"and, for, to, other, the, in"
17673,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.125,"the, were, in, china"
17674,"t some virus detected in pangolins 

were capable of infecting humans.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.125,"virus, in, were"
17675,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.125,"the, and, of, bat, to"
17676,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.125,"the, an, to, of, and"
17677,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.125,"the, of, to, bat"
17678,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.125,"in, the, evolution, of, to, and"
17679,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.125,"the, and, an, to, of"
17680,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.125,"a, between, and, the, of, bat, in"
17681,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.125,"viruses, similar, the, in, of, and, suggesting, a"
17682,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.125,"the, covid-19, to, bat, that, a, but"
17683,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.125,"of, the, in, a, to, that, events, can"
17684,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.125,"all, have, a, of, to"
17685,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.125,"a, from, which, with, sars-cov-2"
17686,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.125,"a, of, from, relatives, sars-cov-2"
17687,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.125,"sars-cov-2, is, to, coronavirus, the"
17688,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.125,"to, the, coronavirus, sars-cov-2, is"
17689,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.125,"the, genome, coronavirus, to, bat, as, related"
17690,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.125,"the, genetic, similarity, sars-cov-2, to"
17691,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.125,"are, other, it, was, sars-cov-2, to, and, in"
17692,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.125,"in, was, similar, to, sars-cov-2, the"
17693,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.125,"are, the, of, viruses"
17694,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.125,"the, to, similarity, sars-cov-2"
17695,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.125,"by, of, to, are, the, sars-cov-2"
17696,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.125,"sars-cov-2, the, of, similarity, to"
17697,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.125,"similar, to, and, the, of"
17698,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.125,"are, to, is, of, the, and"
17699,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.125,"that, to, and, 97.4%"
17700,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.125,"in, the, sars, of, found, that, for, virus, similar, to, by, a, is, closely, related"
17701,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.125,"the, of, that, to, human"
17702,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","This suggests that the BANAL series may be able to directly infect  

humans.",0.125,"to, the, may, be"
17703,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","This suggests that the BANAL series may be able to directly infect  

humans.",0.125,"that, to, be"
17704,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","This suggests that the BANAL series may be able to directly infect  

humans.",0.125,"to, the, that, this, be"
17705,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","This suggests that the BANAL series may be able to directly infect  

humans.",0.125,"able, to, the"
17706,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.125,"from, the, sars-cov-, 2"
17707,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.125,"the, is, from, in"
17708,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.125,"at, the, of, a"
17709,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.125,"the, is, to, a, closely, related"
17710,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.125,"and, a, which, is, the, viruses, to"
17711,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.125,"is, to, have, the, same, which"
17712,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.125,"sars-cov-2, of, the, and, furin, cleavage, site"
17713,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.125,"the, and, for, sars-cov-2"
17714,"According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.125,"to, the, group, of"
17715,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.125,"to, highest, the, virus, of, sars-cov-2,"
17716,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.125,"in, bats, and"
17717,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.125,"known, to, be, the"
17718,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.125,"most, sars-cov-2, to"
17719,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.125,"to, be, the, most"
17720,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.125,"is, sars-cov-2, to, the, in"
17721,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.125,"are, the, coronaviruses,, and, more, than, other"
17722,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.125,"in, the, a, coronaviruses, are, to, and, with"
17723,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.125,"to, the, and, may, are, more, sars-cov-2, than"
17724,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.125,"sars-cov-2, is, be, that, and, the"
17725,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.125,"in, the, it, is, that, sars-cov-2, and"
17726,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.125,"with, zoonotic, events"
17727,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.125,"to, december, by, and, was, the"
17728,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.125,"the, with, at, of, and, to"
17729,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.125,"to, the, sars, zoonotic, infections, not, a, in, of, 2004, had, that, have, an, isolated, humans, or, further"
17730,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.125,"at, an, had, to, a, animal, in, the, virus, or, sars, all, live, suggesting, zoonotic, of, also"
17731,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.125,"the, market, only, that, in, for, of, to, by, with, who, a, had"
17732,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.125,"the, of, closely, related, is, by, for, in, found, a, virus, similar, to, sars, that"
17733,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.125,"from, as, ferret, and, raccoon, to, was, for, by, the, of, that, may, in, a"
17734,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.125,"human, and, from, of, this, the, virus, into, humans"
17735,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.125,"the, species, barrier, into, humans,, to, of, and"
17736,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.125,"with, the, and, for, of, a, or, to, that, were, in, this, sars, palm, likely"
17737,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.125,"a, of, the, from, that, and, at, in, were, both, humans"
17738,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.125,"and, the, virus, was, from, to, a, in"
17739,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.125,"virus, that, from, an, to, a, human"
17740,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.125,"and, from, in, were, found, to, closely, related, that, the, of"
17741,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.125,"that, sars, had, a, zoonotic, the, an, humans, or, of, in, further, infections, isolated, 2004, not, have, to"
17742,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.125,"one, of, similarity, to, a, genome, which, previously, from, bat, in, yunnan"
17743,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.125,"sars, had, a, zoonotic, the, virus, an, animal, or, of, in, at, suggesting, also, all, to, live"
17744,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.125,"an, a, the, huanan, seafood, with, at, was, on, and, market, january, 1,, of, to"
17745,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.125,"on, in, the, hubei, of, chinese, and, an, with, at, huanan, seafood"
17746,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.125,"is, that, released, a, by, had, the, in, before, january, 2020"
17747,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.125,"a, of, market, in, that, for, with, by, only, had, the, who, to"
17748,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.125,"the, of, animal, with, and, early, cases, huanan, market, that, sars-cov-2, at, in"
17749,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.125,"for, the, of, and, were, that, palm, a, in, sars, this, likely, or, with, to"
17750,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.125,"a, and, of, the, huanan, in"
17751,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.125,"positive, samples, the, western, of, in"
17752,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.125,"to, a, seafood, and, market"
17753,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.125,"cases, one, the, of, a, to, spillover"
17754,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.125,"the, huanan, seafood, and, is"
17755,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.125,"to, a, and, animal, in"
17756,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.125,"in, the, that, a, led, to, spillover"
17757,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.125,"this, and, to, the, that, in"
17758,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.125,"the, of, that, market, in, is, covid-19"
17759,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.125,"is, at, all, that, the, of"
17760,"Bats are natural hosts of many of the known  

coronaviruses","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.125,"are, of, many, the, known"
17761,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.125,"the, first, covid-19, and, that, but, one"
17762,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.125,"sars-cov-2, in, a, of, and, that, the, therefore, or, for"
17763,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.125,"the, was, this, market,, it, would, that, in, of"
17764,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.125,"half, of, the, were, to, huanan, and, that"
17765,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.125,"a, the, is, to, infected, with, sars-cov-2"
17766,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.125,"is, that, sars-cov-2, a, the, virus, its"
17767,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.125,"the, is, that, virus, to, a"
17768,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.125,"is, that, sars-cov-2, a, the, pandemic, virus"
17769,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.125,"to, that, natural, the, most, is"
17770,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.125,"the, that, sars-cov-2, to, a, with"
17771,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.125,"is, the, with, for, sars-cov-2"
17772,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","expended to make the simple point 

that COVID-19 had a natural origin.",0.125,"the, that, a, natural"
17773,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","expended to make the simple point 

that COVID-19 had a natural origin.",0.125,"that, a, natural, the"
17774,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","expended to make the simple point 

that COVID-19 had a natural origin.",0.125,"that, to, a, the"
17775,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.125,"of, the, natural, reservoirs"
17776,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.125,"a, viruses, to, the, of"
17777,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.125,"the, of, and, a, in, viruses, to"
17778,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.125,"in, of, to, and, the"
17779,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.125,"a, the, to, and, in"
17780,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.125,"the, of, viruses, in, a, and, to"
17781,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.125,"viruses, to, the, results, in, and"
17782,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.125,"to, and, a, the, of"
17783,zoonotic origins of SARS-CoV-2 by natural evolution,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.125,"zoonotic, sars-cov-2, natural"
17784,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.125,"zoonotic, in, and, humans"
17785,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.125,"in, a, was, and"
17786,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.125,"was, in, animal, origin"
17787,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.125,"sars-cov-2, a, and, an"
17788,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.125,"the, genomic, sars-cov-2, that, in"
17789,"All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.125,"the, that, in, a, sars-cov-2"
17790,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.125,"its, the, virus, a, in"
17791,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.125,"a, the, sequence, with, sars-cov-2"
17792,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.125,"that, the, a, bat, discovered"
17793,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.125,"virus, in, with, sars-cov-2, the, sequence"
17794,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.125,"that, the, sars-cov-2, its, genomic"
17795,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.125,"a, bat, samples, in, sars-cov-2"
17796,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.125,"in, the, with, 96.2%, identity"
17797,"Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.125,"is, clearly, a"
17798,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.125,"sars-cov-2, is, a, that"
17799,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.125,"is, that, a, sars-cov-2, to, or"
17800,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.125,"of, sars-cov-2, not, that, the, a"
17801,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.125,"this, that, natural, selection, the, of"
17802,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.125,"that, of, is, a"
17803,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.125,"of, that, it, is"
17804,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.125,"of, it, is, that, related"
17805,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.125,"the, for, have, been"
17806,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.125,"that, not, from, is, any, used"
17807,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","atural  

selection in an animal host before zoonotic  

transfer;",0.125,"host, an, animal"
17808,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","natural selection in humans  

following zoonotic transfer",0.125,"natural, selection, in"
17809,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.125,"that, to, bat, as, the"
17810,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.125,"the, of, is, to, bat, for"
17811,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.125,"the, its, reservoir, bats"
17812,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.125,"is, it, likely, that, of, to"
17813,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.125,"the, is, to, likely"
17814,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.125,"bats, the, reservoir, for, of"
17815,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.125,"suggests, that, from, to, is, a, in, the"
17816,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.125,"the, that, spike, in, a, efficiently, human, to"
17817,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.125,"is, the, to, sars-cov-2,, its, in"
17818,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.125,"the, a, in, to, bind, that, not, sars-cov-2,"
17819,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.125,"the, of, in, is, to, coronaviruses"
17820,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.125,"this, to, that, natural, the, of, is"
17821,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.125,"the, of, in, binding, spike, protein, that, this, natural"
17822,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.125,"the, that, a, of, natural"
17823,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.125,"can, that, the, and, of"
17824,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.125,"through, the, that, sars-cov-2, of"
17825,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.125,"a, of, that, sars-cov-2, the"
17826,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.125,"a, it, that, the, sars-cov-2, is"
17827,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.125,"the, of, can, to, that, sars-cov-2"
17828,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.125,"in, we, that, the, to"
17829,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.125,"that, in, an, to, humans."
17830,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.125,"the, to, that, was, very"
17831,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.125,"was, that, the, sars-cov-2, also, to"
17832,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.125,"the, sars-cov-2, of, virus, to, that"
17833,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.125,"t, the, also, that, virus"
17834,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.125,"sars-cov-2, very, to, the, of"
17835,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.125,"a, from, the, with, sars-cov-2"
17836,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.125,"the, of, sars-cov-2, and, more, from"
17837,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.125,"recombination, the, of, from, a, with"
17838,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.125,"the, sars-cov-2, and, of, is, in, coronaviruses, nature,"
17839,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.125,"based, the, of, and, that, sars-cov-2, is"
17840,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.125,"the, of, coronaviruses, including, do, not"
17841,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.125,"and, of, is, that, related, in, including"
17842,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","In the 

case of MERS, dromedaries were the principal host.",0.125,"of, the, in, were"
17843,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","In the 

case of MERS, dromedaries were the principal host.",0.125,"of, the, in"
17844,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.125,"that, the, bat, covid-19, but, a, to"
17845,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.125,"the, that, first, covid-19, and, but, one"
17846,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.",0.125,"a, in, the, pandemic, bats."
17847,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.125,"the, a, coronavirus, that, bat"
17848,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.125,"genome, analysis, of, the, covid-19, showed"
17849,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.125,"that, the, covid-19, of, bat"
17850,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.125,"discovered, a, that, the, bat"
17851,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.125,"the, after, covid-19, a, most"
17852,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.125,"the, virus, that, in, animal"
17853,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.125,"a, to, spike, in, the, that, efficiently, human"
17854,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.125,"origin, of, likely, based, on"
17855,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.125,"in, more, to, the, than"
17856,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.125,"the, than, in, and, mers-cov"
17857,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.125,"and, the, bats, to, in"
17858,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.125,"genetic, the, in, bats, and, to"
17859,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.125,"the, more, to, in, and"
17860,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.125,"the, of, more, to, than"
17861,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.125,"the, to, that, bats,, and"
17862,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.125,"animals, from, that, to, and, the"
17863,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.125,"that, which, animals, and, from"
17864,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.125,"and, that, the, covid-19, to"
17865,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.125,"to, the, genus, and, that, animals, covid-19"
17866,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.125,"the, phylogenetic, that, and, to"
17867,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",The COVID-19 most likely developed from bat origin coronaviruses,0.125,"the, likely, origin, covid-19"
17868,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",The COVID-19 most likely developed from bat origin coronaviruses,0.125,"from, the, covid-19"
17869,Coronaviruses account for over 30% of the world’s viruses.,The COVID-19 most likely developed from bat origin coronaviruses,0.125,"coronaviruses, the"
17870,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",The COVID-19 most likely developed from bat origin coronaviruses,0.125,"the, origin, bat"
17871,Many of these CoVs can infect several animal species as well,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.125,"of, these, animal, species, as"
17872,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.125,"bat, is, the, thus, that, hosts, for"
17873,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.125,"viruses, indicating, that, the, of"
17874,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.125,"the, sequence, of, amino, acid"
17875,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.125,"virus, the, covid-19, to, and, that"
17876,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.125,"the, of, covid-19, through, genomic"
17877,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.125,"analysis, of, the, that, and"
17878,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.125,"in, of, and, that, the, intermediate, hosts"
17879,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.125,"the, of, to, through, humans, and"
17880,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.125,"the, to, market,, that, in, of"
17881,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.125,"that, bats, the, hosts, to"
17882,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.125,"to, that, the, virus, bats, of"
17883,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.125,"of, are, viruses, a"
17884,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.125,"are, of, coronaviruses, including"
17885,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.125,"a, of, coronaviruses, including"
17886,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.125,"to, be, through, humans, and"
17887,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.125,"and, in, zoonotic, humans"
17888,"This suggests that the BANAL series may be able to directly infect  

humans.","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.125,"that, be, to"
17889,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.125,"that, are, to"
17890,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.125,"that, originated, in"
17891,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.125,"to, are, in"
17892,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",Bats are hosts of many coronaviruses,0.125,"hosts, are, of"
17893,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.125,"in, an, animal, to"
17894,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.125,"covid-19, in, the, market"
17895,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.125,"seafood, in, wuhan,, the"
17896,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.125,"be, to, the, seafood"
17897,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.125,"the, market, to"
17898,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.125,"the, in, is"
17899,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.125,"that, virus, to, for, and, the"
17900,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.125,"bat, sars-like, and, the"
17901,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.125,"analysis, of, the, covid-19, virus, and"
17902,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.125,"revealed, and, the, of, virus, bat"
17903,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.125,"and, the, of, to, it, that, is"
17904,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.125,"it, is, that, of"
17905,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.125,"similar, to, the, of, and, that, covid-19"
17906,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.125,"the, bats, in, emergence, of, china"
17907,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.125,"of, and, similar, viruses, suggesting, a, in, the"
17908,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.125,"the, that, covid-19, to, genus, and, animals"
17909,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.125,"of, covid-19, that, similar, to, the, and"
17910,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.125,"the, natural, of, in, viruses, for"
17911,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.125,"bats, the, for, viruses, of, and"
17912,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.125,"that, were, the, animals, virus"
17913,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.125,"the, in, which, that, they, virus"
17914,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.125,"of, patients, the, in, china"
17915,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.125,"the, was, in, to, animals"
17916,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.125,"in, of, to, have, the, that, was, first, this"
17917,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.125,"in, animals, to, of, the, has, was"
17918,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.125,"the, was, in, that, even, of"
17919,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.125,"the, market,, it, would, that, was, of, in, this"
17920,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.125,"that, the, in, to, market,, of"
17921,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.125,"in, the, of, was, first"
17922,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.125,"that, have, been, of, with, to, the"
17923,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.125,"that, the, of, this, has, been"
17924,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.125,"that, has, the, with, of, to"
17925,"bats are also important reservoir species for a great 

range of coronaviruses","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.125,"bats, a, great, of"
17926,"An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.125,"reservoir, of, species"
17927,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.125,"the, of, that, is"
17928,Many of these CoVs can infect several animal species as well,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.125,"of, several, species"
17929,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.125,"is, that, the, reservoir"
17930,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.125,"that, natural, the, of"
17931,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.125,"is, the, in, rhinolophus, from"
17932,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.125,"is, the, species, from"
17933,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.125,"is, from, in, the"
17934,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.125,"and, be, transmission, to, humans, other, in, with"
17935,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.125,"or, bats, in, to, transmission, be"
17936,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.125,"or, bats, cave, can, be, of, to, and, in, other, mammals"
17937,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.125,"the, and, is, to"
17938,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.125,"and, be, to, humans, the, between"
17939,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.125,"the, and, to, is"
17940,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.125,"is, bats, the, to"
17941,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.125,"to, the, bats, be, direct"
17942,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.125,"sold, are, to, be, and, of, transmission"
17943,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.125,"as, of, and, are, if, to, they, be, some, more, virus"
17944,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.125,"are, in, be, to"
17945,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.125,"transmission, to, or, be, in, bats"
17946,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.125,"to, or, other, mammals, can, be, of, and, in, cave, bats"
17947,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.125,"sars-cov, such, as, ferret, and, raccoon, to, by, the, of, may, been, in"
17948,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.125,"a, and, was, in"
17949,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.125,"the, first, was, in, of"
17950,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.125,"of, the, in, wildlife, and"
17951,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.125,"in, and, the, of"
17952,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.125,"the, of, lineage, and, geographic, sars-cov-2, in"
17953,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.125,"from, the, been, have, sars-cov-2"
17954,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.125,"in, the, of, and, wildlife"
17955,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.125,"have, been, of, and, pangolins, the, sars-cov-2"
17956,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.125,"of, the, virus, isolated, from, in, with"
17957,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.125,"in, amino, acid, with, of"
17958,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.125,"virus, sequence, with, the, sars-cov-2, in"
17959,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.125,"the, sars-cov-2, with, at, of, virus"
17960,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","t some virus detected in pangolins 

were capable of infecting humans.",0.125,"virus, were, in"
17961,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.125,"have, from, an, between, and, in, china"
17962,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.125,"that, a, and, is"
17963,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.125,"that, the, of, a, and"
17964,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.125,"the, is, that, of, covid-19, and"
17965,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.125,"the, most, for, from, animals"
17966,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.125,"the, which, covid-19, most"
17967,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.125,"is, from, to, a"
17968,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.125,"the, most, a, after, covid-19"
17969,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.125,"have, the, reservoir, a, of, including, and"
17970,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.125,"that, the, of, to, a, bat, whereas"
17971,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.125,"and, that, the, has, to, of, bat"
17972,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.125,"as, to, the, of, most, a, bat"
17973,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.125,"such, been, by, and, to, the, of, has"
17974,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.125,"genome, and, bat, has, been"
17975,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.125,"a, bat, and, sequence, identity, with, human"
17976,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.125,"bat, and, ratg13,, sequence, with"
17977,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.125,"the, and, is, in"
17978,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.125,"bats, and, the"
17979,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.125,"is, and, the, in"
17980,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.125,"and, the, disease, is"
17981,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.125,"the, is, in"
17982,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.125,"other, of, coronaviruses, such, as"
17983,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.125,"that, the, virus, is"
17984,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","zoonotic corona- 

viruses have become an increasing threat to human health,",0.125,"to, human, zoonotic"
17985,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.125,"zoonotic, to, the, and"
17986,"Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.125,"based, on, of, likely, origin"
17987,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.125,"of, natural, based, on, sars-, cov-2, analysis"
17988,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.125,"has, been, that, are, the, of, by"
17989,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.125,"of, scientific, data, the, that, a"
17990,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.125,"that, sars-cov-2, to, bat, host"
17991,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.125,"did, not, a, that, it"
17992,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.125,"it, that, sars-cov-2, to, an, intermediate"
17993,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.125,"in, to, sars-cov-2, from, evolved, an"
17994,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.125,"sars-cov-2, to, host, or"
17995,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.125,"sars-cov-2, to, is, a, or, that"
17996,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.125,"suggest, that, may, sars-cov-2, to, humans, in"
17997,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.125,"the, reservoir, of, a"
17998,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.125,"the, that, sars-cov-2, not, a"
17999,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.125,"the, of, sars-cov-2, a, that, not"
18000,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.125,"that, been, a, of, the, sars-cov-2"
18001,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.125,"the, of, sars-cov-2, but"
18002,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.125,"that, sars-cov-2, has, the, of"
18003,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.125,"that, the, sars-cov-2, a"
18004,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.125,"been, the, for, have"
18005,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.125,"sars-cov-2, of, for, to, a, such, have, that, not, in, and, genetically, the"
18006,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.125,"its, that, it, to, such, this, as, the, had, by, a, of, been, for"
18007,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.125,"it, been, in, the, and, to, that, may, have, infect"
18008,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.125,"in, may, the, of, from, that, for, as, raccoon, ferret, was, to, by, a, and"
18009,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.125,"the, by, of, to, such, as, and, raccoon, in, sars-cov, been, ferret, may"
18010,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.125,"the, sars-cov-2"
18011,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.125,"t, that, sars-cov-2, been"
18012,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.125,"sars-cov-2, animal, that, in"
18013,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.125,"humans, that, sars-cov-2, animal, species"
18014,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.125,"sars-cov-2, that, in"
18015,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.125,"that, animal, has, been"
18016,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.125,"to, bat, the, sars-cov-2"
18017,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.125,"the, was, to, sars-cov-2"
18018,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.125,"the, bat, to, be"
18019,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",Genetic evidence suggesting otherwise is yet to be presented.,0.125,"is, be, to"
18020,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",Genetic evidence suggesting otherwise is yet to be presented.,0.125,"genetic, to, be"
18021,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.125,"of, the, hypothesis, that, sars-cov-2, is"
18022,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.125,"the, of, for, it, is, that, sars-cov-2, with"
18023,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.125,"the, as, a, has, and"
18024,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.125,"the, natural, of, has"
18025,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.125,"as, the, of, a, human"
18026,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.125,"and, the, of, natural, origin, has"
18027,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.125,"origin, of, sars-cov-2, have, been, by"
18028,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.125,"the, sars-cov-2, and, have, to, of, is, in"
18029,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.125,"the, natural, origin, to, in, and"
18030,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.125,"the, has, been, of, to, by, such, and"
18031,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.125,"the, of, natural, origin, has, and"
18032,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.125,"and, nucleotide, sars-cov-, 2"
18033,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.125,"identical, to, sars-cov-2"
18034,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.125,"to, that, and, was"
18035,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.125,"that, sars-cov-2, and, are"
18036,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.125,"was, that, and, to"
18037,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.125,"are, identical, to, that"
18038,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.125,"that, viruses, to, sars-cov-2"
18039,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.125,"to, and, was, sars-cov-2"
18040,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.125,"that, sars-cov-2, from, to"
18041,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.125,"are, to, that, sars-cov-2, and, ratg13"
18042,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.125,"to, that, ratg13, from, and"
18043,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.125,"that, sars-cov-2, and, to"
18044,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.125,"sars-cov-2, that, are, to, ratg13, and"
18045,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.125,"and, in, recently, found, to, that, of, bats, are, sars-cov-2"
18046,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.125,"similarity, of, sars-cov-2, with"
18047,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.125,"sars-cov-2, with, bat, ratg13"
18048,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.125,"the, as, from, viruses"
18049,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.125,"that, the, most, as"
18050,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.125,"the, and, that, is, an, to, by"
18051,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.125,"that, is, from, an, to"
18052,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.125,"from, that, to, ratg13, and"
18053,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.125,"to, the, with, sars-cov-2"
18054,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.125,"the, sars-cov-2, to, of, be"
18055,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.125,"the, be, of, to"
18056,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.125,"to, genetic, similarity, sars-cov-2, the"
18057,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.125,"of, similarity, with, sars-cov-2"
18058,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.125,"be, the, of, sars-cov-2"
18059,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.125,"of, sars-cov, and, bat, sequences, ratg13, similar"
18060,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.125,"observed, sars-cov-2, and, bat, ratg13"
18061,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.125,"we, sars-cov-2, and, bat, ratg13"
18062,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.125,"sars-cov-2, sequences, similar, and, of"
18063,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.125,"to, the, of, sars-cov-2, plausible"
18064,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.125,"the, to, its, in"
18065,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.125,"the, of, which, rbd, sars-cov-2"
18066,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.125,"the, was, to, in, sars-cov-2"
18067,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.125,"sars-cov-2, also, to, the, of"
18068,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.125,"that, sars-cov-2, are, to, and, hypothesis, the, origin, of"
18069,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.125,"that, the, and, this, is"
18070,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.125,"is, natural, that, to, the, most"
18071,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.125,"to, the, this, that, is, of, natural"
18072,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.125,"this, is, and, to, the, that"
18073,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.125,"genomic, studies, that, sars-cov-2, the"
18074,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.125,"that, genomic, the, sars-cov-2, its"
18075,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.125,"studies, that, sars-cov-2, be"
18076,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.125,"all, that, sars-cov-2, a, and"
18077,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.125,"the, coronavirus, that, from, to, bat, and"
18078,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.125,"the, to, sars-cov-2, from, a, bat"
18079,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.125,"bats, are, and"
18080,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.125,"that, are, sars-cov-2, and"
18081,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.125,"that, probable, sars-cov-2"
18082,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.125,"more, than, the, covid-19, that"
18083,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.125,"the, that, also, virus, t"
18084,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.125,"that, genome, are, also, the"
18085,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.125,"is, a, of, at, the, market, in"
18086,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.125,"that, is, in, wuhan, from, a, to"
18087,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.125,"a, of, to, that, by, the, virus"
18088,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.125,"a, was, that, the, to, is, previously, by"
18089,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.125,"the, of, et, genome, virus, is, to, that"
18090,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.125,"the, for, a, to, that, bat"
18091,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.125,"a, the, to, sars-cov-2"
18092,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.125,"that, the, bats, to, hosts"
18093,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.125,"bats, to, is, the"
18094,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.125,"the, most, that, as"
18095,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.125,"that, the, sars-cov-2, likely, bats"
18096,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.125,"bats, are, hosts, a, to, that, as"
18097,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.125,"many, and, a, virus, that"
18098,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.125,"a, that, the, and, to, which"
18099,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.125,"bat, covs, that, the, of, and, analysis"
18100,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.125,"sars-cov-2, at, the, of, outbreak"
18101,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.125,"the, of, patients, in, china"
18102,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.125,"from, to, a, similarity, found, in, bat"
18103,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.125,"genome, sequence, of, from, was, to, bat"
18104,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.125,"in, a, of, one, to, yunnan, from, which, bat, similarity, genome, previously"
18105,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.125,"holmes, also, the, of, and, their, in, to"
18106,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.125,"of, the, sars-cov-2, is, to, genomes"
18107,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.125,"a, for, sars-cov-2, similarity, the, in"
18108,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.125,"viruses, to, and, a, the, which, is"
18109,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.125,"in, the, of, is, to, sars-cov-2, which"
18110,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.125,"animals, that, are, be, sars-cov-2"
18111,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.125,"that, a, virus, of, with, sars-cov-2"
18112,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.125,"of, the, that, ratg13,, and, sars-cov-2"
18113,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.125,"been, the, and, are, to, that, may, have"
18114,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.125,"the, are, to, sars-cov-2, by, of"
18115,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.125,"the, to, have, that, been, with, of"
18116,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.125,"of, the, sars-cov-2, have, been, pangolins, and"
18117,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.125,"of, sars-cov-2, been, that, the, a"
18118,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.125,"the, with, sars-cov-2, that, are, hosts, for"
18119,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.125,"to, that, sars-cov-2, the, virus, of, recombination"
18120,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.125,"in, the, this, that, spike, protein, binding, of, natural"
18121,"This suggests that the BANAL series may be able to directly infect  

humans.","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.125,"the, able, to"
18122,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.125,"in, that, the, and, of"
18123,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.125,"of, the, that"
18124,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.125,"the, is, of"
18125,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.125,"the, is, that"
18126,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.125,"the, that, of"
18127,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.125,"that, of, the, is"
18128,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.125,"the, sarbecovirus, sars, and, sequences, are, sars-, cov-2"
18129,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.125,"the, and, to, in, whole, genome"
18130,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.125,"the, that, are, to, be, and"
18131,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.125,"bats, the, to, be, or, could, for, and"
18132,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.125,"viruses, in, and, to, results, the"
18133,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.125,"that, sars-cov-2, is, bat, bats, the"
18134,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.125,"that, the, is, bat, thus, hosts, for"
18135,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.125,"that, with, are, the, hosts, for, sars-cov-2"
18136,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.125,"that, the, sars-cov-2, this, more, bats"
18137,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.125,"and, viruses, from, of, this, the"
18138,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.125,"and, sars-cov-2, bats, of, more"
18139,"Bats have been reported as being the rich source of 

coronaviruses","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.125,"bats, been, the, of"
18140,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.125,"the, of, from, and, more, sars-cov-2"
18141,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.125,"the, this, that, has, been, of"
18142,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.125,"that, bats, the, likely, sars-cov-2"
18143,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.125,"this, the, sars-cov-2, that, bats, more"
18144,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.125,"the, sars-cov-2, and, this, of"
18145,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.125,"the, viruses, and, bat, that, to"
18146,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.125,"the, sars-cov-2, to, bat, cov)"
18147,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.125,"and, this, in, the, that, to"
18148,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.125,"this, to, that, the, and, is"
18149,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.125,"the, this, that, sars-cov-2, is, in"
18150,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same",0.125,"the, same, bat, cov"
18151,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.125,"is, to, have, the, in"
18152,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.125,"to, have, the, which, is, same"
18153,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.125,"the, pangolin, host, sars-cov-2"
18154,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.125,"that, the, of, sars-cov-2, is, to, bat, cov"
18155,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.125,"the, to, that, are, sars-cov-2, bat, in, and"
18156,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.125,"the, of, bat, cov"
18157,Originating from reservoir of bat,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.125,"of, bat"
18158,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.125,"the, of, sars-, bat"
18159,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.125,"in, that, the, are, more"
18160,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.125,"the, that, in, for, sars-cov-2"
18161,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.125,"the, and, sars-cov-2, is, bat"
18162,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.125,"cov, bat, that, the, sars-cov-2, and, similarity"
18163,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.125,"the, which, that, sars-cov-2, ratg13, pangolin"
18164,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.125,"the, with, sars-cov-2, origin"
18165,"�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.125,"cov, bat, the, same"
18166,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.125,"more, than, bats, of"
18167,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.125,"the, origin, of, that, sars-cov-2"
18168,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.125,"that, the, are, more"
18169,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.125,"this, the, of, that, sars-cov-2"
18170,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.125,"and, their, the, of, sars-cov-2"
18171,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.125,"the, of, sars-cov-2, bat, and"
18172,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.125,"the, of, sars-cov-2, and, this"
18173,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.125,"have, in, or, may"
18174,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.125,"sars-cov-2, n, that, may, in, bats"
18175,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.125,"that, sars-cov-2, originated"
18176,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.125,"to, sars-cov-2, that, bats, and, the, as"
18177,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.125,"are, to, may, more, sars-cov-2, than, the, and"
18178,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.125,"the, genome, of, reported, bat"
18179,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.125,"of, the, genome, virus, and, bat"
18180,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.125,"on, in, the, of, and, patients, these, reported"
18181,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.125,"sars-cov-2, other, and, a, that"
18182,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.125,"similar, sequences, of, sars-cov-2, and"
18183,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.125,"that, are, the, sars-cov-2, to, hypothesis, of, origin, and"
18184,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.125,"the, genome, also, that, are"
18185,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.125,"that, the, of, to, with, a"
18186,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.125,"sars-cov-2, to, are, bat, the"
18187,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.125,"are, to, the, likely, of"
18188,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.125,"sars-cov-2, to, cov, the, of"
18189,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.125,"a, sars-cov-2, with, the, cov"
18190,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.125,"sars-cov-2, a, that, with, to, the"
18191,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.125,"to, and, showed, that, sars-cov-2"
18192,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.125,"that, pangolin-cov, and, sars-cov-2"
18193,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.125,"and, 97.4%, to, that"
18194,"with the first case being linked to  

a seafood market","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.125,"with, the, to"
18195,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.125,"the, of, to, with, and"
18196,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.125,"the, sars-cov, of, is, and, with"
18197,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.125,"of, the, and, with"
18198,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.125,"the, with, to, of"
18199,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.125,"sars-cov-2, is, with, to, the"
18200,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.125,"is, sars-cov-2, and, to, the"
18201,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.125,"the, and, identity, sars-cov-2, same"
18202,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.125,"the, of, sars-cov-2, and, is, but"
18203,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.125,"the, of, and, is"
18204,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.125,"the, of, with, and, sars-cov-2"
18205,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.125,"of, the, sars-cov-2, is, and"
18206,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.125,"of, sars-cov-2, but, the"
18207,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.125,"is, the, same, with, sars-cov-2"
18208,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.125,"of, the, showed, with, identity"
18209,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.125,"the, of, identity, with, sars-cov-2"
18210,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.125,"from, transmission, for, and, the"
18211,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.125,"for, the, recombination, of, and, in, that"
18212,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.125,"that, the, of, in, and"
18213,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.125,"for, sars-cov-2, the, in"
18214,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.125,"in, that, the, and, sars-cov-2"
18215,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.125,"sars-cov-2, in, the, that, for, of"
18216,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.125,"the, for, sars-cov-2"
18217,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.125,"the, of, bats, hosts, for"
18218,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.125,"a, are, that, the, of"
18219,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.125,"a, the, of, bats"
18220,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.125,"the, of, sars-cov, and, that, a, are"
18221,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.125,"a, of, have, and, the, reservoir, including"
18222,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.125,"sars-cov-2, is, with, the, for"
18223,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.125,"is, similarity, sars-cov-2, and, the"
18224,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.125,"the, in, to, and"
18225,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.125,"the, are, identical, to"
18226,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.125,"to, and, the, sars-cov-2"
18227,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.125,"are, to, in"
18228,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.125,"and, in, to, the, sars-cov-2"
18229,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.125,"the, that, natural, selection, and"
18230,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.125,"the, of, natural, selection, that, this"
18231,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.125,"that, the, of, virus, and"
18232,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.125,"might, virus, the, and"
18233,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.125,"that, sars-cov-2, to, with, the"
18234,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.125,"the, sars-cov-2, at, that, and"
18235,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.125,"that, the, virus, and, to, at"
18236,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.125,"the, has, similarity, with, sars-cov-2"
18237,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.125,"the, at, and, to, of, with"
18238,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.125,"the, phylogenetic, that, to, and"
18239,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.125,"virus, at, with, sars-cov-2, the, of"
18240,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.125,"bat, that, the, of, this"
18241,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.125,"and, that, recombination, of, bat"
18242,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.125,"in, an, of, and, the"
18243,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.125,"and, can, the, of, that"
18244,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.125,"of, that, the, bat, and"
18245,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.125,"the, bat, be, in, of"
18246,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.125,"the, from, identity, sars-cov-2"
18247,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.125,"that, transmitted, from, to"
18248,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.125,"of, that, to, the, was"
18249,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.125,"from, to, sars-cov-2,, that, the, of, bats, sars-cov-2"
18250,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.125,"to, sars-cov-2, in, at, the"
18251,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.125,"is, that, sars-cov-2, the, of, virus, at"
18252,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.125,"of, sars-cov-2, in, which, is, the, to"
18253,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.125,"the, sars-cov-2, as"
18254,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.125,"sars-cov-2, the, host, pangolin"
18255,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.125,"for, the, sars-cov-2"
18256,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.125,"the, this, sars-cov-2, for"
18257,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.125,"the, has, to, similarity, sars-cov-2"
18258,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.125,"but, to, of, the, virus, has, bats"
18259,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.125,"that, sars-cov-2, to, bats, be, the"
18260,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.125,"the, of, virus, to, sars-cov-2,, highest"
18261,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.125,"that, the, virus, bats, to, of"
18262,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.125,"bats, to, direct, be, the"
18263,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.125,"that, recombination, of, virus, to, the, sars-cov-2"
18264,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.125,"the, of, from, with, a, recombination"
18265,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.125,"in, animal, that, the, as, for"
18266,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.125,"origin, was, in, animal"
18267,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.125,"the, first, was, that, in"
18268,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.125,"that, in, the, for"
18269,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.125,"in, the, that, animal, for"
18270,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.125,"that, be, sars-cov-2, studies"
18271,"civet cats and raccoon dogs  

are the intermediate hosts","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.125,"and, the, intermediate"
18272,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.125,"sars-cov-2, an, animal, host, and, bat"
18273,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.125,"the, and, be, of"
18274,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.125,"the, sars-cov-2, an, of, bat"
18275,"atural  

selection in an animal host before zoonotic  

transfer;","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.125,"an, animal, host"
18276,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.125,"the, of, sars-cov-2, be"
18277,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.125,"the, sars-cov-2, be, and, between"
18278,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.125,"might, and, the, virus"
18279,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.125,"a, for, the, of, is, virus, in, that"
18280,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.125,"in, the, a, that, at, time, for"
18281,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.125,"that, the, this, virus, is"
18282,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.125,"indicates, that, the, of, in, a"
18283,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.125,"a, for, sars-cov-2, the, in"
18284,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.125,"this, is, sars-cov-2, the, that, in"
18285,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.125,"the, a, that, originated, in"
18286,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.125,"sars-cov-2, human, in, animal, or"
18287,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.125,"in, a, the, pandemic, bats."
18288,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.125,"of, and, to, the, reservoir"
18289,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.125,"relatives, of, from, a, sars-cov-2"
18290,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.125,"a, sars-cov-2, in, bat, samples"
18291,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.125,"coronaviruses, a, of, including"
18292,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.125,"sars-cov-2, may, a, that, in"
18293,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.125,"and, in, to, bats, of, many, which"
18294,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.125,"humans,, which, to, of, severe, and, respiratory"
18295,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.125,"that, bats, are, hosts, as, to, a"
18296,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.125,"the, closest, in, 96.2%, was"
18297,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.125,"in, the, rhinolophus, found"
18298,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.125,"96.2%, identity, with, the, in"
18299,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.125,"of, the, in, was, to, sars-cov-2"
18300,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.125,"to, sars-cov-2, that, was, the"
18301,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.125,"the, of, sars-cov-2, r."
18302,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.125,"the, of, detected, in"
18303,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.125,"in, the, of, to, that, sars-cov-2"
18304,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.125,"was, in, similar, to, sars-cov-2, the"
18305,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.125,"the, of, that, sars-cov-2, to"
18306,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.125,"the, of, that, sars-cov-2, in"
18307,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.125,"can, that, naturally, to, furin, cleavage"
18308,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.125,"that, the, of, in, events, can, a, to"
18309,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.125,"of, natural, the, furin, cleavage, site, similar, to, in"
18310,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.125,"sars-cov-2, is, and, from, be, to, that, coronavirus, in, bats"
18311,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.125,"in, the, of, found, that, from, were, to, and, closely, related"
18312,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.125,"recently, found, in, bats, are, to, that, of, sars-cov-2, and"
18313,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.125,"the, of, to, sars-cov-2,, that, sars-cov-2, from, bats"
18314,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.125,"the, to, bat, coronavirus, sequence"
18315,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.125,"the, of, sequence, is, to, bat"
18316,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.125,"the, in, amino, acid, sequence, be"
18317,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.125,"is, to, sars-cov-2,, its, in, the"
18318,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.125,"in, be, the, of, bat"
18319,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.125,"bat, ratg13, to, the, of"
18320,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.125,"a, of, to, has, that, the, and"
18321,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.125,"a, to, sars-cov-2,, in, the, that, not, bind"
18322,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.125,"that, of, is, to, bat, it"
18323,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.125,"is, to, that, in, bats,, and"
18324,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.125,"is, that, of, viruses, similar, to"
18325,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.125,"it, is, that, of, related"
18326,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.125,"of, to, bat, it, is, that"
18327,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.125,"including, and, in, related, that, of, is"
18328,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.125,"the, pangolin, to, have, with"
18329,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.125,"s, protein, with, that, of"
18330,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.125,"that, the, with, of, to, pangolin-cov"
18331,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.125,"is, more, than, to"
18332,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.125,"the, of, is, to, ratg13,"
18333,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.125,"the, amino, acid, to, of"
18334,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.125,"the, of, more, than, to"
18335,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.125,"sars-cov-2, to, be, of, and, the, ability"
18336,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.125,"the, virus, zoonotic, and, be, of, to"
18337,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.125,"natural, of, sars-, cov-2, based, on, analysis"
18338,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.125,"natural, of, the, cleavage, site, in, furin, similar, to"
18339,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.125,"the, of, and, bat, coronaviruses, ratg13, to"
18340,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.125,"bat, similarity, to, sars-cov-2"
18341,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.125,"the, of, very, to, sars-cov-2"
18342,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.125,"ratg13, the, bat, to, of"
18343,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.125,"the, sars-cov-2, that, is"
18344,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.125,"sars-cov-2, that, the, a"
18345,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.124137931,"the, live, on, most, and, were, in, with, by, of, a, as, to, available, that, infected, one, virus"
18346,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.124137931,"the, live, to, in, a, of, as, one, with, on, available, most, that, infected, virus, were, by, and"
18347,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.124087591,"as, a, of, the, market, live, were, in, to, find, for, found, that, from, tested, positive, same"
18348,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.124087591,"in, a, of, to, the, find, that, from, were, live, market, for, found, same, as, tested, positive"
18349,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.124087591,"spread, from, reservoir, intermediate, as, and, it, to, not, for, by, the, of, that, suggested, in, a"
18350,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.124087591,"as, a, of, the, and, by, in, to, spread, it, for, that, from, suggested, intermediate, not, reservoir"
18351,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.123893805,"to, the, bats, a, in, of, study, species, from, analysis, that, an, humans, found"
18352,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.123893805,"in, the, of, an, sars, was, a, at, that, virus, humans, to, human, than"
18353,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.123893805,"that, sars, a, the, virus, was, an, humans, than, human, of, in, at, to"
18354,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.123893805,"study, that, of, from, bats, to, humans, an, a, found, in, analysis, species, the"
18355,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.123809524,"and, of, the, have, to, civet, cats, with, sars-cov, bat, spillover, may, occurred"
18356,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.123809524,"in, a, year, to, coronaviruses, the, from, for, coronavirus, novel, and, at, any"
18357,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.123809524,"in, may, the, animals, live, of, that, as, market, was, were, infected, a"
18358,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.123809524,"to, have, occurred, with, the, of, and, sars-cov, may, bat, civet, cats, spillover"
18359,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.123809524,"in, with, the, and, to, that, is, of, bat, are, as, they, cluster"
18360,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.123809524,"was, that, the, infected, in, may, market, live, animals, were, as, a, of"
18361,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.123809524,"in, the, year, a, novel, coronavirus, coronaviruses, from, to, at, any, and, for"
18362,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.123809524,"several, a, of, some, also, zoonotic, and, the, to, from, one, species, including"
18363,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.123809524,"some, to, a, from, the, one, zoonotic, of, several, and, also, including, species"
18364,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.123809524,"and, the, of, bat, to, are, as, cluster, they, with, that, in, is"
18365,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.12371134,"animals, for, of, one, bats,, with, that, bats, infected, virus, were, and"
18366,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.12371134,"that, the, of, market, in, was, to, live, were, we, have, a"
18367,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.12371134,"in, a, of, to, have, the, we, that, was, were, live, market"
18368,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.12371134,"the, of, in, species, horseshoe, bats, and, or, viral, china, south, asia"
18369,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.12371134,"live, animal, at, markets, a, known, and, in, the, that, to, sars"
18370,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.12371134,"the, viral, or, species, of, horseshoe, bats, in, asia, and, south, china"
18371,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.12371134,"one, of, animals, bats,, and, that, bats, for, virus, were, infected, with"
18372,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.12371134,"that, by, a, of, virus, with, one, to, and, are, the, for"
18373,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.12371134,"of, with, a, to, any, early, wuhan, and, the, huanan, market, in"
18374,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.12371134,"and, with, wuhan, to, the, huanan, market, in, early, of, a, any"
18375,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.12371134,"the, between, covid-19, cases, and, huanan, market, is, of, suggesting, a, to"
18376,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.12371134,"live, animal, at, a, risk, and, this, in, the, that, to, sars"
18377,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.12371134,"cases, the, huanan, and, of, suggesting, a, to, covid-19, is, between, market"
18378,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.12371134,"in, the, known, sars, live, animal, markets, that, at, to, a, and"
18379,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.12371134,"the, and, a, risk, to, that, in, this, sars, live, animal, at"
18380,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.12371134,"the, are, to, a, for, of, one, with, that, virus, by, and"
18381,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.123595506,"in, 2003,, the, sars, of, from, also, to, is, closely, related"
18382,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.123595506,"and, the, of, bat, similar, viruses, are, a, different, this, in"
18383,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.123595506,"this, of, and, similar, viruses, are, different, bat, a, in, the"
18384,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.123595506,"the, of, sars, in, 2003,, is, also, closely, related, to, from"
18385,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.123595506,"evidence, in, the, and, that, of, collected, were, to, taken, from"
18386,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.123595506,"the, of, with, huanan, seafood, market, and, in, environmental, collected, at"
18387,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.123595506,"and, with, environmental, at, the, huanan, seafood, market, in, of, collected"
18388,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.123595506,"the, of, and, were, that, collected, from, in, taken, evidence, to"
18389,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.12345679,"the, of, scientific, that, sars-cov-2, a, virus, has, in, for"
18390,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.12345679,"be, of, the, and, with, to, in, virus, ability, ace2"
18391,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.12345679,"sars-cov-2-related, from, a, and, with, sars-cov-2, has, to, in, the"
18392,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.12345679,"of, virus, that, is, similar, to, the, bat, and, for"
18393,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.12345679,"and, the, of, bat, to, similar, that, for, virus, is"
18394,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.12345679,"to, sars-cov-2, from, a, in, the, and, has, with, sars-cov-2-related"
18395,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.12345679,"in, the, obtained, by, using, to, that, is, of, shows"
18396,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.12345679,"by, using, obtained, in, shows, that, the, is, to, of"
18397,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.12345679,"sars-cov-2, of, has, for, a, virus, scientific, that, in, the"
18398,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.12345679,"the, of, virus, and, be, in, with, ability, to, ace2"
18399,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.123287671,"that, the, of, in, recombination, as, can, a, to"
18400,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.123287671,"the, is, that, of, are, with, and, in, also"
18401,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.123287671,"the, that, a, virus, found, in, this, causes, covid-19"
18402,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.123287671,"and, the, it, that, was, for, sars-cov-2, a, by"
18403,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.123287671,"the, of, that, virus, sequence, found, in, this, to"
18404,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.123287671,"its, to, this, was, the, of, that, sars-cov-2, in"
18405,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.123287671,"the, a, species, of, that, over, from, to, humans"
18406,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.123287671,"a, as, the, recombination, of, can, in, that, to"
18407,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.123287671,"in, these, are, and, sars-cov-2, with, bat, the, than"
18408,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.123287671,"this, found, in, the, of, sequence, that, to, virus"
18409,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.123287671,"of, the, early, cases, have, in, that, by, chinese"
18410,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.123287671,"are, also, the, of, is, and, in, with, that"
18411,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.123287671,"a, it, was, that, the, sars-cov-2, and, for, by"
18412,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.123287671,"in, a, the, virus, that, causes, covid-19, this, found"
18413,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.123287671,"the, that, have, in, of, cases, by, chinese, early"
18414,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.123287671,"that, of, from, to, humans, a, species, over, the"
18415,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.123287671,"this, its, in, the, of, that, sars-cov-2, was, to"
18416,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.123287671,"et, al., origin, of, sars-cov-2, by, complete, the, in"
18417,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.123287671,"et, al., the, complete, sars-cov-2, by, in, of, origin"
18418,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.123287671,"in, viruses, 2, and, sars-cov-2, ratg13, the, between, is"
18419,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.123287671,"and, in, to, be, that, the, bats, are, hosts"
18420,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.123287671,"are, in, with, sars-cov-2, than, these, the, bat, and"
18421,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.123287671,"and, between, sars-cov-2, ratg13, in, is, the, viruses, 2"
18422,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.123287671,"are, to, the, in, and, that, bats, be, hosts"
18423,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.123188406,"a, of, the, market, palm, animal, by, in, to, sars, with, for, that, none, tested, positive, guangdong"
18424,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.123188406,"a, of, market, in, guangdong, that, animal, tested, positive, for, sars, with, palm, by, none, the, to"
18425,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.123076923,"the, to, which, sars-cov, with, of, and, infection"
18426,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.123076923,"these, viruses, are, and, all, bat, that, the"
18427,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.123076923,"of, had, history, wuhan, and, the, only, in"
18428,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.123076923,"transmitted, from, to, a, are, and, coronaviruses, in"
18429,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.123076923,"the, novel, coronavirus, that, from, was, to, and"
18430,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.123076923,"in, a, coronaviruses, are, transmitted, from, to, and"
18431,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.123076923,"the, that, spillover, of, sars-cov-2, into, from, a"
18432,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.123076923,"from, to, indicating, that, the, of, are, sars-cov-2"
18433,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.123076923,"in, from, of, were, sars-cov-2, and, the, humans"
18434,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.123076923,"the, of, in, from, early, that, this, at"
18435,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.123076923,"that, a, progenitor, of, sars-cov-2, into, the, genomic"
18436,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.123076923,"that, sars-cov-2, are, and, a, the, origin, of"
18437,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.123076923,"in, a, to, the, we, are, that, market"
18438,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.123076923,"lineage, cases, the, huanan, that, in, study, a"
18439,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.123076923,"the, that, of, cases, lineage, in, one, also"
18440,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.123076923,"the, virus, for, and, other, viruses, to, in"
18441,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.123076923,"and, the, of, to, viruses, are, closely, related, different, that, into, in, turn, can, is, its"
18442,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.123076923,"in, a, we, that, the, are, to, market"
18443,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.123076923,"positive, from, the, market, that, of, in, for"
18444,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.123076923,"the, analysis, that, are, likely, for, covid-19, virus"
18445,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.123076923,"the, of, is, to, that, sars-cov-2, and, a"
18446,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.123076923,"the, as, was, a, that, virus, to, and"
18447,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.123076923,"of, cases, had, to, the, market, exposed, in"
18448,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.123076923,"the, of, by, a, virus, to, that, genetic"
18449,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.123076923,"that, from, bats, to, humans, a, in, the"
18450,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.123076923,"a, have, and, the, to, from, animals, through"
18451,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.123076923,"the, palm, civets, at, that, samples, from, civet"
18452,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.123076923,"the, genome, of, sars-cov, bat, s, similar, to"
18453,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.123076923,"study, genome, the, is, to, of, sars-like, previously"
18454,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.123076923,"to, with, the, of, and, sars-cov, which, infection"
18455,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.123076923,"transmission, to, or, be, with, of, and, bats"
18456,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.123076923,"be, transmission, to, another, usually, of, and, more"
18457,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.123076923,"the, novel, coronavirus, was, that, from, to, and"
18458,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.123076923,"the, of, sars, that, virus, to, moreover,, and"
18459,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.123076923,"sars-cov-2, a, sequence, between, and, from, bat, in"
18460,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.123076923,"s, the, genome, of, similar, to, bat, sars-cov"
18461,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.123076923,"a, sequence, between, sars-cov-2, and, from, bat, in"
18462,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.123076923,"in, a, sars-cov-2, to, be, coronavirus, that, may"
18463,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.123076923,"viruses, to, the, have, of, and, these, a"
18464,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.123076923,"of, from, bats, host, a, shares, with, the"
18465,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.123076923,"that, a, the, of, sars-cov-2, and, is, to"
18466,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.123076923,"that, the, in, bats, to, humans, from, a"
18467,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.123076923,"with, the, of, bats, a, host, shares, from"
18468,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.123076923,"sars-cov-2-related, from, and, identity, with, sars-cov-2, in, the"
18469,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.123076923,"of, the, from, sars-cov-2, and, in, were, humans"
18470,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.123076923,"such, and, to, the, of, sars-cov-2, natural, is"
18471,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.123076923,"and, also, a, of, sars-cov-2, in, the, for"
18472,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.123076923,"are, that,, to, in, may, these, the, and"
18473,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.123076923,"of, the, from, this, that, early, at, in"
18474,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.123076923,"in, of, the, that, from, market, for, positive"
18475,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.123076923,"to, that, sars-cov-2, has, the, bats, of, recombination"
18476,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.123076923,"in, the, and, to, viruses, for, other, virus"
18477,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.123076923,"the, viruses, that, to, are, closely, related, in, is, different, its, of, can, and, turn, into"
18478,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.123076923,"a, of, genetic, to, that, by, the, virus"
18479,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.123076923,"in, that,, the, and, are, to, these, may"
18480,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.123076923,"the, samples, from, civets, at, that, civet, palm"
18481,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.123076923,"moreover,, and, that, the, virus, to, sars, of"
18482,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.123076923,"that, from, a, to, in, an, intermediate, host"
18483,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.123076923,"wuhan, the, in, history, of, only, and, had"
18484,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.123076923,"of, cases, to, the, market, in, had, exposed"
18485,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.123076923,"cases, in, also, one, lineage, the, of, that"
18486,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.123076923,"the, that, these, are, also, with, of, is"
18487,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.123076923,"the, that, sars-cov-2, a, of, spillover, into, from"
18488,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.123076923,"in, a, study, that, the, lineage, cases, huanan"
18489,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.123076923,"in, this, it, be, that, the, and, of"
18490,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.123076923,",, natural, of, the, spike, in, to, that"
18491,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.123076923,"a, of, the, that, sars-cov-2, genomic, progenitor, into"
18492,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.123076923,"have, the, of, to, a, and, these, viruses"
18493,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.123076923,"bats, to, be, or, with, of, transmission, and"
18494,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.123076923,"usually, and, more, transmission, of, to, another, be"
18495,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.123076923,"through, have, the, and, to, from, animals, a"
18496,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.123076923,"the, sars-cov-2-related, from, and, in, identity, with, sars-cov-2"
18497,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.123076923,"in, an, intermediate, host, a, that, from, to"
18498,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.123076923,"the, is, that, of, are, with, these, also"
18499,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.123076923,"such, and, the, of, to, sars-cov-2, is, natural"
18500,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.123076923,"the, are, likely, virus, that, covid-19, analysis, for"
18501,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.123076923,"the, genome, of, is, to, sars-like, previously, study"
18502,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.123076923,"sars-cov-2, also, in, a, of, and, the, for"
18503,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.123076923,"the, viruses, and, are, all, bat, that, these"
18504,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.123076923,"ratg13, is, the, bat, to, closest, in, of"
18505,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.123076923,"in, that, the, bats, are, likely, hosts, sars-cov-2"
18506,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.123076923,"a, origin, of, the, that, sars-cov-2, and, are"
18507,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.123076923,"and, found, to, that, the, of, are, sars-cov-2"
18508,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.123076923,"and, the, it, be, that, of, in, this"
18509,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.123076923,"to, sars-cov-2, recombination, of, bats, the, has, that"
18510,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.123076923,"sars-cov-2, a, be, to, that, may, coronavirus, in"
18511,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.123076923,",, to, in, the, that, spike, of, natural"
18512,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.123076923,"are, to, indicating, that, the, of, sars-cov-2, from"
18513,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.123076923,"the, in, that, bats, are, likely, hosts, sars-cov-2"
18514,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.123076923,"found, that, sars-cov-2, are, to, and, the, of"
18515,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.123076923,"is, the, coronavirus, to, be, sars-cov-2,, in, of"
18516,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.123076923,"in, the, to, is, of, bat, ratg13, closest"
18517,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.123076923,"in, to, be, sars-cov-2,, the, of, coronavirus, is"
18518,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.123076923,"to, and, of, highly, that, rmyn02, in, bat"
18519,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.123076923,"rmyn02, and, in, to, that, highly, bat, of"
18520,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.12295082,"of, in, that, wild, animal, traders, positive, for, with, civet, had, the, who, to, related"
18521,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.12295082,"of, the, to, wild, related, civet, animal, traders, who, in, with, had, that, positive, for"
18522,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.12295082,"had, from, reservoir, as, civets,, and, to, not, for, the, of, that, have, in, a"
18523,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.12295082,"to, the, as, for, and, not, a, reservoir, in, of, from, had, that, have, civets,"
18524,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.122807018,"the, of, from, pangolins, a, and, or"
18525,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.122807018,"have, the, and, of, virus, to, bat"
18526,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.122807018,"the, was, to, it, in, with, of"
18527,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.122807018,"the, of, have, sequences, that, sars-cov-2, to"
18528,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.122807018,"genetic, and, have, is, recombination, of, bat"
18529,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.122807018,"genetic, and, human, a, of, the, is"
18530,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.122807018,"of, a, the, to, which, bat, and"
18531,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.122807018,"the, between, sars-cov-2, and, bat, is, which"
18532,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.122807018,"a, in, the, that, sars-cov-2, from, laboratory"
18533,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.122807018,"the, of, to, it, that, sars-cov-2, is"
18534,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.122807018,"the, virus, to, that, sars-cov-2, human, and"
18535,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.122807018,"to, share, ancestor, sars-cov-2, the, bat, and"
18536,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.122807018,"the, of, animal, and, that, sars-cov-2, humans"
18537,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.122807018,"that, have, of, to, and, the, sars-cov-2"
18538,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.122807018,"is, that, the, virus, as, of, a"
18539,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.122807018,"the, of, a, in, to, that, bats, with, as, and, virus, also, ace2, for"
18540,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.122807018,"the, as, of, from, to, humans, hosts"
18541,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.122807018,"to, in, the, this, that, is, of"
18542,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.122807018,"to, sars-cov-2, of, the, and, that, with"
18543,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.122807018,"the, from, that, to, a, and, coronavirus"
18544,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.122807018,"sars-cov-2, through, has, been, identified, to, extend"
18545,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.122807018,"to, sars-cov-2, in, the, this, is, of"
18546,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.122807018,"evidence, to, the, of, bats, pangolins, sars-cov-2"
18547,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.122807018,"a, by, who, was, that, the, virus"
18548,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.122807018,"identified, sars-cov-2, has, been, to, extend, through"
18549,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.122807018,"similarity, sars-cov-2, and, bat, to, between, in"
18550,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.122807018,"studies, from, in, china, bat, between, and"
18551,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.122807018,"found, sars-cov-2, from, and, coronaviruses, as, high"
18552,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.122807018,"that, are, the, of, two, viruses, least"
18553,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.122807018,"the, a, of, that, from, to, bat"
18554,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.122807018,"this, that, are, the, origin, of, sars-cov-2"
18555,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.122807018,"of, from, humans, intermediate, host, sars-cov-2, the"
18556,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.122807018,"the, of, that, humans, and, animal, sars-cov-2"
18557,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.122807018,"the, sars-cov-2, in, from, an, of, a"
18558,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.122807018,"the, sars-cov-2, to, humans, from, in, of"
18559,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.122807018,"the, to, sars-cov-2, in, from, of, a"
18560,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.122807018,"the, from, that, sars-cov-2, to, a, also"
18561,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.122807018,"that, the, infected, with, animals, were, as"
18562,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.122807018,"the, an, is, to, that, of, and"
18563,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.122807018,"the, is, that, to, a, of, and"
18564,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.122807018,"the, pandemic, is, of, sars-cov-2, to, a"
18565,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.122807018,"the, and, is, of, evidence, a, to"
18566,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.122807018,"the, of, evidence, that, sars-cov-2, is, a"
18567,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.122807018,"a, and, bat, as, to, that, coronavirus"
18568,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.122807018,"that, the, of, and, is, to, an"
18569,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.122807018,"sars-cov-2, a, and, that, the, as, intermediate"
18570,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.122807018,"that, and, be, intermediate, sars-cov-2, to, the"
18571,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.122807018,"a, that, the, and, for, to, which"
18572,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.122807018,"the, of, which, that, to, pangolin, virus"
18573,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.122807018,"the, and, to, is, of, bat, pangolin"
18574,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.122807018,"and, to, be, the, of, is, hosts"
18575,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.122807018,"sars-cov-2, the, of, that, have, to, sequences"
18576,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.122807018,"is, an, which, based, on, the, by"
18577,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.122807018,"a, virus, from, to, bats, and, are"
18578,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.122807018,"the, genetic, and, of, virus, is, to"
18579,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.122807018,"a, as, the, of, is, virus, that"
18580,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.122807018,"who, in, that, the, virus, to, were"
18581,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.122807018,"the, is, to, previous, for, sars-cov, be"
18582,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.122807018,"the, animals, that, infected, with, were, as"
18583,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.122807018,"that, with, the, of, may, have, as"
18584,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.122807018,"the, for, a, which, to, that, and"
18585,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.122807018,"the, sars-cov-2, to, ace2, is, a, that"
18586,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.122807018,"that, the, is, a, ace2, receptor, for"
18587,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.122807018,"to, previous, the, is, be, for, sars-cov"
18588,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.122807018,"analysis, the, with, at, of, and, to"
18589,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.122807018,"to, have, the, of, and, bat, virus"
18590,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.122807018,"to, is, of, the, virus, genetic, and"
18591,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.122807018,"and, have, of, genetic, is, bat, recombination"
18592,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.122807018,"is, and, very, to, through, close, contact"
18593,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.122807018,"coronavirus, the, of, virus, and, that, to"
18594,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.122807018,"genome, from, wuhan, the, bat, of, and"
18595,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.122807018,"are, hosts, of, and, which, disease, respiratory"
18596,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.122807018,"are, to, that, of, amino, acid, sequences"
18597,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.122807018,"of, that, similar, to, the, bat, and"
18598,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.122807018,"as, a, coronavirus, that, bat, and, to"
18599,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.122807018,"as, to, may, be, a, high, bat"
18600,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.122807018,"coronaviruses, to, that, sars-cov-2, bat, in, and"
18601,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.122807018,"a, sequence, that, 96.2%, sars-cov-2, in, bat"
18602,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.122807018,"that, sars-cov-2, from, a, bat, to, in"
18603,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.122807018,"et, a, of, sars-cov-2, sequences, at, the"
18604,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.122807018,"that, sars-cov-2, the, at, of, and, similarity"
18605,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.122807018,"that, a, the, of, and, is, to"
18606,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.122807018,"in, the, from, an, a, of, sars-cov-2"
18607,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.122807018,"from, in, the, of, a, sars-cov-2, to"
18608,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.122807018,"a, bat, be, as, high, to, may"
18609,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.122807018,"viruses, similar, to, the, of, that, covid-19"
18610,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.122807018,"in, to, related, that, the, is, sars-cov-2"
18611,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.122807018,"virus, the, to, and, that, human, sars-cov-2"
18612,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.122807018,"the, of, with, a, and, more, sars-cov-2"
18613,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.122807018,"of, the, sars-cov-2, been, in, is, and"
18614,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.122807018,"a, in, the, that, sars-cov-2, human, for"
18615,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.122807018,"the, of, sars-cov-2, humans, from, intermediate, host"
18616,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.122807018,"sars-cov-2, a, of, in, has, that, with"
18617,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.122807018,"the, species, of, from, to, humans, and"
18618,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.122807018,"that, the, of, sars-cov-2, is, to, it"
18619,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.122807018,"the, of, to, it, is, that, as"
18620,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.122807018,"sars-cov-2, a, that, and, the, as, intermediate"
18621,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.122807018,"to, sars-cov-2, be, that, and, the, intermediate"
18622,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.122807018,"provide, evidence, to, that, the, of, and"
18623,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.122807018,"that, a, in, has, of, with, sars-cov-2"
18624,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.122807018,"it, that, bats, the, sars-cov-2, to, a"
18625,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.122807018,"a, the, of, sars-cov-2, pandemic, is, to"
18626,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.122807018,"sars-cov-2, and, coronaviruses, bat, to, that, in"
18627,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.122807018,"coronaviruses, in, are, to, that, sars-cov-2, and"
18628,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.122807018,"the, to, bat, and, sars-cov-2, share, ancestor"
18629,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.122807018,"bat, the, with, sars-cov-2, are, more, than"
18630,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.122807018,"the, is, that, first, covid-19, and, in"
18631,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.122807018,"a, on, and, to, of, the, huanan"
18632,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.122807018,"bats, also, a, for, as, the, of, virus, and, in, with, that, to, ace2"
18633,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.122807018,"the, a, huanan, and, to, of, on"
18634,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.122807018,"a, the, of, and, evidence, is, to"
18635,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.122807018,"in, is, that, the, covid-19, and, first"
18636,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.122807018,"natural, of, and, a, which, to, in"
18637,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.122807018,"sars-cov-2, a, sequence, bat, 96.2%, that, in"
18638,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.122807018,"a, that, the, sars-cov-2, ace2, to, is"
18639,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.122807018,"as, the, of, to, it, that, is"
18640,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.122807018,"the, of, that, to, in, is, this"
18641,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.122807018,"the, sars-cov-2, to, in, of, this, is"
18642,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.122807018,"a, of, and, the, or, from, pangolins"
18643,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.122807018,"the, of, more, sars-cov-2, with, and, a"
18644,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.122807018,"is, very, close, contact, and, to, through"
18645,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.122807018,"evidence, that, the, covid-19, a, ace2, animal"
18646,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.122807018,"in, bats, more, to, of, both, and"
18647,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.122807018,"a, that, the, ace2, receptor, for, is"
18648,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.122807018,"the, that, ace2, a, animal, evidence, covid-19"
18649,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.122807018,"the, of, and, bat, that, similar, to"
18650,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.122807018,"that, the, of, viruses, similar, to, covid-19"
18651,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.122807018,"viruses, are, least, two, that, the, of"
18652,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.122807018,"have, of, in, bats, the, rhinolophus, china"
18653,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.122807018,"of, the, two, in, and, that, viruses"
18654,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.122807018,"of, the, in, was, it, to, with"
18655,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.122807018,"rhinolophus, bats, the, of, have, in, china"
18656,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.122807018,"in, the, activity, or, during, caves, bats."
18657,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.122807018,"are, and, virus, from, bats, to, a"
18658,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.122807018,"in, the, of, is, sars-cov-2, been, and"
18659,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.122807018,"to, the, of, from, as, hosts, humans"
18660,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.122807018,"from, species, of, to, and, the, humans"
18661,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.122807018,"and, that, a, of, the, most, likely"
18662,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.122807018,"of, a, that, the, to, bat, and"
18663,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.122807018,"sars-cov-2, a, from, bat, to, that, in"
18664,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.122807018,"sars-cov-2, a, of, the, has, been, that"
18665,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.122807018,"the, and, a, of, genetic, is, human"
18666,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.122807018,"the, a, of, that, most, likely, and"
18667,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.122807018,"based, on, the, is, an, which, by"
18668,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.122807018,"amino, acid, sequences, are, to, that, of"
18669,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.122807018,"coronaviruses, to, that, are, sars-cov-2, in, and"
18670,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.122807018,"of, more, to, and, both, in, bats"
18671,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.122807018,"the, a, coronavirus, that, from, to, and"
18672,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.122807018,"from, also, the, that, a, sars-cov-2, to"
18673,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.122807018,"who, a, that, the, virus, was, by"
18674,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.122807018,"who, the, were, to, that, virus, in"
18675,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.122807018,"at, was, found, in, province,, the, genome"
18676,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.122807018,"to, sars-cov-2, a, bats, the, it, that"
18677,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.122807018,"the, and, which, to, a, of, bat"
18678,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.122807018,"the, a, of, that, to, bat, and"
18679,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.122807018,"the, sequences, of, sars-cov-2, at, a, et"
18680,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.122807018,"the, of, to, that, have, and, sars-cov-2"
18681,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.122807018,"that, the, of, and, two, viruses, in"
18682,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.122807018,"the, bat, or, pangolin, of, sars-, cov"
18683,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.122807018,"are, more, with, sars-cov-2, than, the, bat"
18684,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.122807018,"sars-cov-2, to, similarity, between, and, in, bat"
18685,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.122807018,"the, pangolin, is, to, of, bat, and"
18686,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.122807018,"of, the, bat, cov, or, sars-, pangolin"
18687,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.122807018,"the, between, sars-cov-2, and, which, is, bat"
18688,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.122807018,"origin, of, the, this, that, sars-cov-2, are"
18689,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.122807018,"that, the, of, bats, are, likely, sars-cov-2"
18690,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.122807018,"the, sars-cov-2, to, bats, pangolins, evidence, of"
18691,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.122807018,"that, the, of, evidence, and, to, provide"
18692,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.122807018,"from, studies, between, and, in, bat, china"
18693,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.122807018,"the, genome, of, from, wuhan, bat, and"
18694,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.122807018,"that, a, likely, the, of, sars-cov-2, to"
18695,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.122807018,"analysis, the, to, at, with, of, and"
18696,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.122807018,"bats, are, hosts, of, and, a, that"
18697,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.122807018,"that, a, the, of, sars-cov-2, evidence, is"
18698,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.122807018,"that, sars-cov-2, from, a, laboratory, the, in"
18699,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.122807018,"in, the, for, that, sars-cov-2, human, a"
18700,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.122807018,"caves, or, bats., activity, during, the, in"
18701,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.122807018,"hosts, and, are, of, disease, which, respiratory"
18702,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.122807018,"a, of, in, natural, and, to, which"
18703,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.122807018,"that, bats, are, hosts, a, of, and"
18704,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.122807018,"genome, was, at, in, province,, the, found"
18705,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.122807018,"sars-cov-2, of, the, similar, to, in, protein"
18706,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.122807018,"the, is, to, be, of, hosts, and"
18707,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.122807018,"the, that, is, in, related, to, sars-cov-2"
18708,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.122807018,"that, bats, are, the, likely, of, sars-cov-2"
18709,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.122807018,"sars-cov-2, from, as, high, and, coronaviruses, found"
18710,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.122807018,"that, the, with, may, have, as, of"
18711,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.122807018,"in, similar, to, of, sars-cov-2, the, protein"
18712,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.122641509,"from, the, was, for, time, to, a, that, with, and, in, coronavirus, at"
18713,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.122641509,"in, the, of, as, a, that, virus, infected, to, moreover,, and, closely, related"
18714,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.122641509,"and, the, of, infected, to, as, a, closely, related, moreover,, that, in, virus"
18715,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.122641509,"in, the, a, coronavirus, was, that, from, to, at, time, and, with, for"
18716,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.12244898,"that, in, and, the, new, of"
18717,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.12244898,"animal, reservoir, to, are, and, species"
18718,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.12244898,"that, bats, more, for, virus, than"
18719,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.12244898,"to, in, more, sars-cov-2, than, and"
18720,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.12244898,"and, of, sars-cov-2, in, which, to"
18721,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.12244898,"to, the, of, spillover, into, from"
18722,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.12244898,"the, of, sars-cov-2, with, is, to"
18723,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.12244898,"t, is, unlikely, that, a, sars-cov-2"
18724,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.12244898,"that, a, virus, with, and, sars-cov-2"
18725,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.12244898,"the, to, bat, and, that, human"
18726,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.12244898,"a, of, sars-cov-2, found, to, that"
18727,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.12244898,"the, and, bat, that, to, human"
18728,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.12244898,"and, that, the, bat, ratg13, was"
18729,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.12244898,"of, many, species,, such, as, and"
18730,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.12244898,"that, sequences, similar, pangolin, and, of"
18731,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.12244898,"the, of, with, and, sars-cov-2, in"
18732,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.12244898,"in, to, is, of, the, and"
18733,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.12244898,"that, the, and, to, humans, of"
18734,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.12244898,"a, sequence, and, the, virus, in"
18735,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.12244898,"close, humans, of, sars-cov-2, to, intermediate"
18736,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.12244898,"the, of, bats, as, for, from"
18737,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.12244898,"is, that, infected, on, to, the"
18738,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.12244898,"this, is, to, the, that, in"
18739,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.12244898,"on, in, wuhan, the, origin, of"
18740,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.12244898,"in, the, of, is, to, that"
18741,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.12244898,"animal, to, a, and, in, china"
18742,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.12244898,"the, of, a, sars-cov-2, to, spillover"
18743,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.12244898,"bats, are, important, natural, of, and"
18744,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.12244898,"the, virus, as, that, and, to"
18745,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.12244898,"that, can, domestic, animals, and, from"
18746,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.12244898,"the, virus, into, from, to, and"
18747,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.12244898,"the, to, that, as, hosts, for"
18748,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.12244898,"a, the, is, high, sequence, with"
18749,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.12244898,"sequence, the, a, coronavirus, isolated, from"
18750,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.12244898,"that, the, with, coro-, navirus, of"
18751,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.12244898,"the, and, coro-, navirus, is, to"
18752,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.12244898,"is, that, sars-cov-2, the, of, genome"
18753,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.12244898,"to, with, sars-cov-2, the, bat, and"
18754,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.12244898,"bats, the, to, be, of, and"
18755,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.12244898,"this, of, to, the, in, been"
18756,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.12244898,"this, is, sars-cov-2, to, the, in"
18757,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.12244898,"and, species, are, to, reservoir, animal"
18758,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.12244898,"to, a, and, animal, in, china"
18759,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.12244898,"sars-cov-2, from, to, are, coronaviruses, bat"
18760,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.12244898,"a, host, sars-cov-2, genetic, similarity, in"
18761,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.12244898,"bat, and, species, to, an, in"
18762,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.12244898,"to, the, of, into, from, spillover"
18763,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.12244898,"the, a, of, to, that, from"
18764,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.12244898,"that, a, of, to, the, sars-cov-2"
18765,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.12244898,"the, was, bat, ratg13, and, that"
18766,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.12244898,"the, was, not, have, that, of"
18767,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.12244898,"that, the, to, from, at, a"
18768,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.12244898,"the, from, a, at, to, of"
18769,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.12244898,"are, animals, to, of, the, and"
18770,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.12244898,"transmission, to, be, through, of, and"
18771,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.12244898,"two, of, sars-cov-2, in, from, and"
18772,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.12244898,"the, of, and, that, was, to"
18773,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.12244898,"the, was, huanan, and, to, of"
18774,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.12244898,"that, sars-cov-2, and, is, not, virus."
18775,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.12244898,"the, that, be, animals, with, were"
18776,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.12244898,"the, to, it, that, in, animals"
18777,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.12244898,"in, to, is, covid-19, originated, naturally"
18778,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.12244898,"the, cause, of, outbreak, is, to"
18779,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.12244898,"as, that, virus, to, and, the"
18780,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.12244898,"domestic, animals, can, from, that, and"
18781,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.12244898,"that, the, covid-19, bat, a, high"
18782,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.12244898,"the, been, to, in, of, this"
18783,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.12244898,"of, the, cases, in, to, market"
18784,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.12244898,"by, with, the, covid-19, in, of"
18785,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.12244898,"et, al., the, of, to, in"
18786,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.12244898,"the, sars-cov-2, to, be, is, and"
18787,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.12244898,"that, the, pangolin, to, as, intermediate"
18788,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.12244898,"to, the, that, a, of, from"
18789,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.12244898,"the, genome, that, for, covid-19, virus"
18790,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.12244898,"the, of, sars-cov-2, to, a, that"
18791,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.12244898,"the, of, to, bat, hosts, and"
18792,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.12244898,"of, the, and, that, sars-cov-2, sequences"
18793,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.12244898,"that, the, sars-cov-2, and, is, which"
18794,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.12244898,"are, to, the, in, and, bats"
18795,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.12244898,"a, at, to, that, the, from"
18796,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.12244898,"have, a, in, bats, the, china"
18797,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.12244898,"genetic, and, that, a, the, virus"
18798,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.12244898,"the, and, is, to, in, of"
18799,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.12244898,"the, animals, are, to, and, of"
18800,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.12244898,"is, covid-19, originated, in, naturally, to"
18801,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.12244898,"of, in, and, to, which, the"
18802,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.12244898,"a, of, the, at, that, virus"
18803,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.12244898,"the, of, is, and, sequence, identity"
18804,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.12244898,"or, be, the, for, on, studies"
18805,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.12244898,"the, high, sequence, with, a, is"
18806,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.12244898,"is, the, and, of, sequence, identity"
18807,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.12244898,"a, the, is, of, and, wild"
18808,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.12244898,"the, analysis, that, sars-cov-2, related, to"
18809,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.12244898,"in, the, virus, it, not, that"
18810,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.12244898,"the, of, with, that, coro-, navirus"
18811,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.12244898,"the, that, of, not, supported, a"
18812,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.12244898,"the, by, that, sars-cov-2, and, a"
18813,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.12244898,"the, was, and, that, for, a"
18814,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.12244898,"genome, similar, to, the, of, sars-cov-2."
18815,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.12244898,"and, intermediate, hosts, to, humans, in"
18816,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.12244898,"he, sequence, homology, with, that, of"
18817,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.12244898,"the, genome, et, that, sars-cov-2, and"
18818,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.12244898,"et, bat, of, sars-cov-2, genome, the"
18819,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.12244898,"is, and, likely, that, of, by"
18820,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.12244898,"that, from, to, an, is, a"
18821,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.12244898,"a, from, that, virus, is, to"
18822,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.12244898,"from, virus, to, and, the, into"
18823,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.12244898,"have, been, and, in, to, the"
18824,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.12244898,"to, the, been, from, an, and"
18825,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.12244898,"that, not, virus., sars-cov-2, and, is"
18826,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.12244898,"sars-cov-2, animal, species, and, that, the"
18827,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.12244898,"close, to, of, sars-cov-2, intermediate, humans"
18828,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.12244898,"and, that, is, likely, by, of"
18829,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.12244898,"it, is, that, of, sars-cov-2, through"
18830,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.12244898,"of, an, very, to, that, sars-cov-2"
18831,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.12244898,"to, that, the, of, betacoronavirus, and"
18832,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.12244898,"of, covid-19, in, the, with, by"
18833,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.12244898,"the, in, of, this, was, virus"
18834,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.12244898,"the, sequence, of, coronavirus, that, to"
18835,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.12244898,"the, of, novel, coronavirus, bat, and"
18836,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.12244898,"of, the, sequence, that, coronavirus, to"
18837,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.12244898,"of, the, novel, coronavirus, and, bat"
18838,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.12244898,"a, that, the, sars-cov-2, and, by"
18839,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.12244898,"the, sars-cov-2, and, et, genome, that"
18840,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.12244898,"from, a, to, in, the, that"
18841,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.12244898,"a, the, in, sequence, virus, and"
18842,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.12244898,"the, sars-cov-2, bat, in, china, and"
18843,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.12244898,"that, from, is, a, in, sars-cov-2"
18844,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.12244898,"a, from, in, that, virus, is"
18845,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.12244898,"the, sequence, a, coronavirus, isolated, from"
18846,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.12244898,"viruses, that, are, to, ratg13, and"
18847,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.12244898,"that, sars-cov-2, is, to, be, from"
18848,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.12244898,"that, the, of, in, a, to"
18849,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.12244898,"the, that, of, with, in, at"
18850,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.12244898,"a, was, that, the, and, for"
18851,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.12244898,"sars-cov-2, a, of, and, the, as"
18852,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.12244898,"analysis, that, sars-cov-2, related, to, the"
18853,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.12244898,"the, of, closely, related, virus, to"
18854,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.12244898,"that, related, to, sars-cov-2, found, in"
18855,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.12244898,"was, found, in, closely, related, the"
18856,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.12244898,"in, a, variety, of, and, the"
18857,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.12244898,"of, to, and, the, for, sars-cov-2"
18858,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.12244898,"the, of, from, bats, as, for"
18859,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.12244898,"from, of, bats, were, and, the"
18860,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.12244898,"of, a, the, sars-like, covs, and"
18861,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.12244898,"of, the, two, and, a, with"
18862,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.12244898,"sars-cov-2, host, a, genetic, similarity, in"
18863,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.12244898,"no, to, the, of, sars-cov-2, is"
18864,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.12244898,"that, in, the, virus, it, not"
18865,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.12244898,"that, is, from, an, to, a"
18866,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.12244898,"sars-cov-2, from, a, that, is, in"
18867,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.12244898,"that, sars-cov-2, a, of, virus, genome"
18868,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.12244898,"a, of, the, supported, that, not"
18869,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.12244898,"the, of, is, that, sars-cov-2, and"
18870,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.12244898,"et, al., the, of, in, to"
18871,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.12244898,"the, in, an, to, sars-cov-2, also"
18872,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.12244898,"the, of, bats, were, from, and"
18873,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.12244898,"the, and, is, to, coro-, navirus"
18874,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.12244898,"the, and, similar, to, rbd, is"
18875,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.12244898,"is, bats, the, most, similar, to"
18876,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.12244898,"such, that, sars-cov-2, is, to, be"
18877,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.12244898,"that, sars-cov-2, the, species, and, animal"
18878,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.12244898,"the, of, sars-cov-2, as, a, and"
18879,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.12244898,"the, of, a, variety, and, in"
18880,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.12244898,"animal, species, sars-cov-2, and, in, the"
18881,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.12244898,"the, and, that, sars-cov-2, was, to"
18882,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.12244898,"that, the, in, and, to, a"
18883,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.12244898,"to, sars-cov-2, is, be, and, the"
18884,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.12244898,"the, between, and, is, of, to"
18885,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.12244898,"of, cases, to, the, market, in"
18886,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.12244898,"sars-cov-2, in, animal, species, and, the"
18887,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.12244898,"of, that, the, from, implicating, for"
18888,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.12244898,"the, genome, of, sars-cov-2, that, is"
18889,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.12244898,"that, a, virus, genome, of, sars-cov-2"
18890,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.12244898,"is, unlikely, that, a, sars-cov-2, or"
18891,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.12244898,"the, sars-cov-2, and, of, to, bat"
18892,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.12244898,"sars-cov-2, and, the, bat, in, china"
18893,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.12244898,"bat, and, the, are, all, sars-cov-2"
18894,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.12244898,"an, to, and, in, bat, species"
18895,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.12244898,"the, of, bat, species, in, to"
18896,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.12244898,"of, the, in, and, a, viruses"
18897,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.12244898,"the, between, and, bat, viruses, same"
18898,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.12244898,"are, similar, and, a, the, of"
18899,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.12244898,"a, in, the, that, to, of"
18900,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.12244898,"bat, species, to, in, the, of"
18901,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.12244898,"a, of, sars-cov-2, to, with, common"
18902,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.12244898,"is, similarity, sars-cov-2, bat, to, the"
18903,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.12244898,"the, is, to, sars-cov-2, at, which"
18904,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.12244898,"are, closely, related, to, sars-cov-2, the"
18905,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.12244898,"the, of, is, to, that, and"
18906,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.12244898,"the, and, rbd, is, similar, to"
18907,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.12244898,"the, of, closely, related, to, virus"
18908,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.12244898,"and, sars-cov-2, in, to, more, than"
18909,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.12244898,"the, sars-cov-2, with, and, to, bat"
18910,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.12244898,"are, the, sars-cov-2, to, a, bat"
18911,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.12244898,"a, at, to, the, of, from"
18912,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.12244898,"of, the, to, huanan, and, was"
18913,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.12244898,"to, and, a, on, the, of"
18914,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.12244898,"the, of, to, is, and, between"
18915,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.12244898,"one, evidence, the, of, suggesting, to"
18916,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.12244898,"the, lineage, is, all, collected, in"
18917,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.12244898,"on, the, infected, that, to, is"
18918,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.12244898,"with, the, humans, wildlife, that, is"
18919,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.12244898,"found, in, that, sars-cov-2, related, to"
18920,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.12244898,"in, found, related, and, china,, to"
18921,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.12244898,"the, a, of, which, to, and"
18922,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.12244898,"in, to, of, the, which, and"
18923,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.12244898,"that, the, from, a, in, to"
18924,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.12244898,"this, strong, that, the, is, of"
18925,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.12244898,"that, the, virus, in, jumped, to"
18926,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.12244898,"very, that, of, sars-cov-2, to, an"
18927,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.12244898,"this, virus, the, was, in, of"
18928,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.12244898,"in, to, the, sars-cov-2, also, an"
18929,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.12244898,"the, of, sars-cov-2, more, a, with"
18930,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.12244898,"is, that, the, of, sars-cov-2, coronaviruses"
18931,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.12244898,"that, the, covid-19, virus, originated, in"
18932,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.12244898,"the, covid-19, bat, that, a, high"
18933,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.12244898,"from, the, that, implicating, of, for"
18934,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.12244898,"that, the, hosts, for, a, of"
18935,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.12244898,"the, of, to, that, humans, and"
18936,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.12244898,"the, and, of, virus, to, that"
18937,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.12244898,"the, that, virus, in, covid-19, originated"
18938,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.12244898,"in, of, and, china,, genomic, to"
18939,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.12244898,"indicates, that, bats, are, the, of"
18940,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.12244898,"the, animals, that, be, with, were"
18941,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.12244898,"that, have, not, the, was, of"
18942,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.12244898,"the, that, in, it, to, animals"
18943,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.12244898,"have, the, in, bats, a, china"
18944,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.12244898,"the, is, lineage, in, all, collected"
18945,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.12244898,"through, to, be, and, of, transmission"
18946,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.12244898,"found, in, the, was, closely, related"
18947,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.12244898,"two, of, sars-cov-2, from, in, and"
18948,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.12244898,"sars-cov-2, is, have, in, the, guangdong"
18949,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.12244898,"the, of, sars-cov-2, is, been, in"
18950,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.12244898,"from, in, china, the, between, and"
18951,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.12244898,"a, the, of, wild, is, and"
18952,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.12244898,"strong, the, this, that, is, of"
18953,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.12244898,"the, to, of, hosts, bat, and"
18954,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.12244898,"and, of, many, species,, such, as"
18955,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.12244898,"at, that, the, virus, of, a"
18956,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.12244898,"suggest, that, has, the, origin, or"
18957,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.12244898,"t, is, unlikely, that, sars-cov-2, a"
18958,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.12244898,"is, unlikely, that, sars-cov-2, a, or"
18959,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.12244898,"is, that, humans, with, wildlife, the"
18960,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.12244898,"genetic, that, the, virus, and, a"
18961,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.12244898,"the, have, been, in, to, and"
18962,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.12244898,"is, no, the, of, to, sars-cov-2"
18963,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.12244898,"the, sars-cov-2, has, of, and, to"
18964,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.12244898,"and, that, ratg13, viruses, are, to"
18965,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.12244898,"the, been, from, an, to, and"
18966,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.12244898,"the, of, to, be, is, and"
18967,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.12244898,"studies, on, the, or, be, for"
18968,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.12244898,"more, than, that, bats, for, virus"
18969,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.12244898,"the, virus, for, covid-19, genome, that"
18970,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.12244898,"that, virus, are, the, hosts, for"
18971,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.12244898,"virus, that, is, from, to, a"
18972,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.12244898,"from, a, virus, that, is, in"
18973,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.12244898,"the, bats, is, most, similar, to"
18974,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.12244898,"it, is, that, sars-cov-2, a, the"
18975,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.12244898,"are, a, to, sars-cov-2, the, bat"
18976,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.12244898,"a, sars-cov-2, is, the, for, to"
18977,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.12244898,"the, of, a, sars-like, covs, and"
18978,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.12244898,"the, sars-cov-2, of, et, genome, bat"
18979,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.12244898,"and, sars-cov-2, in, to, of, which"
18980,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.12244898,"is, the, for, sars-cov-2, to, a"
18981,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.12244898,"related, to, found, in, china,, and"
18982,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.12244898,"genomic, in, and, to, china,, of"
18983,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.12244898,"sars-cov-2, with, and, a, virus, that"
18984,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.12244898,"the, that, are, hosts, for, virus"
18985,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.12244898,"sars-cov-2, and, pangolin, to, the, of"
18986,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.12244898,"the, of, and, sequences, that, sars-cov-2"
18987,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.12244898,"with, the, of, a, two, and"
18988,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.12244898,"are, and, the, bats, to, in"
18989,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.12244898,"the, that, to, in, is, this"
18990,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.12244898,"the, sars-cov-2, to, in, this, is"
18991,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.12244898,"bat, to, similarity, is, sars-cov-2, the"
18992,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.12244898,"the, sars-cov-2, have, in, is, guangdong"
18993,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.12244898,"with, the, pangolin, have, to, host"
18994,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.12244898,"the, and, that, sars-cov-2, is, which"
18995,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.12244898,"the, has, that, suggest, or, origin"
18996,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.12244898,"and, viruses, bat, between, the, same"
18997,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.12244898,"and, is, that, viruses, ratg13, bat"
18998,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.12244898,"the, are, sars-cov-2, all, bat, and"
18999,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.12244898,"that, the, of, and, to, betacoronavirus"
19000,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.12244898,"on, the, of, in, wuhan, origin"
19001,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.12244898,"between, and, the, from, in, china"
19002,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.12244898,"sequences, and, that, similar, of, pangolin"
19003,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.12244898,"the, genome, of, similar, to, sars-cov-2."
19004,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.12244898,"of, and, similar, are, a, the"
19005,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.12244898,"the, a, and, to, of, on"
19006,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.12244898,"the, of, with, a, more, sars-cov-2"
19007,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.12244898,"that, with, the, of, pangolin, to"
19008,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.12244898,"the, for, a, of, that, and"
19009,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.12244898,"of, that, the, a, hosts, for"
19010,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.12244898,"of, and, that, the, new, in"
19011,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.12244898,"and, to, the, of, sars-cov-2, has"
19012,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.12244898,"the, of, that, to, in, is"
19013,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.12244898,"to, is, which, sars-cov-2, at, the"
19014,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.12244898,"the, that, virus, to, of, has"
19015,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.12244898,"sars-cov-2, is, from, be, to, that"
19016,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.12244898,"such, to, be, that, sars-cov-2, is"
19017,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.12244898,"the, an, animal, and, of, sars-cov-2"
19018,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.12244898,"of, the, sars-cov-2, been, in, is"
19019,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.12244898,"the, of, to, it, is, and"
19020,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.12244898,"found, that, of, sars-cov-2, to, a"
19021,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.12244898,"to, of, a, common, with, sars-cov-2"
19022,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.12244898,"bats, are, important, and, natural, of"
19023,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.12244898,"of, the, in, similar, to, that"
19024,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.12244898,"in, similar, to, that, of, the"
19025,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.12244898,"to, of, is, ratg13, in, bat"
19026,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.12244898,"that, and, bat, ratg13, is, viruses"
19027,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.12244898,"ratg13, is, bat, to, in, of"
19028,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.12244898,"to, that, the, pangolin, as, intermediate"
19029,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.12244898,"the, one, of, evidence, suggesting, to"
19030,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.12244898,"to, have, the, host, with, pangolin"
19031,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.12244898,"the, of, that, to, with, pangolin"
19032,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.12244898,"of, pangolin, to, and, the, sars-cov-2"
19033,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.122222222,"for, and, with, from, to, at, the, in, a, was, any"
19034,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.122222222,"the, of, and, were, that, into, from, a, in, this, humans"
19035,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.122222222,"chinese, and, an, from, the, market, in, of, a, positive, animal"
19036,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.122222222,"from, in, were, found, to, that, the, of, is, are, likely"
19037,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.122222222,"the, to, a, as, is, available, was, that, bats, virus, and"
19038,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.122222222,"the, was, to, a, that, similar, with, in, of, coronavirus, at"
19039,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.122222222,"in, found, to, closely, related, that, the, of, is, likely, natural"
19040,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.122222222,"a, of, the, from, this, that, and, in, were, into, humans"
19041,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.122222222,"a, coronavirus, in, the, with, that, was, similar, to, of, at"
19042,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.122222222,"to, available, is, a, virus, that, bats, and, was, the, as"
19043,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.122222222,"live, animal, markets, are, a, and, in, the, that, to, sars"
19044,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.122222222,"in, the, a, was, from, to, at, any, and, with, for"
19045,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.122222222,"in, chinese, the, market, positive, from, an, animal, and, a, of"
19046,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.122222222,"the, live, are, to, in, markets, a, sars, that, animal, and"
19047,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.122222222,"in, of, to, the, are, likely, that, is, from, were, found"
19048,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.122222222,"the, of, closely, related, is, likely, natural, in, found, to, that"
19049,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.122137405,"chinese, for, and, from, to, at, the, market, in, of, collected, a, tested, positive, was, animal"
19050,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.122137405,"in, the, animal, of, from, tested, positive, for, chinese, at, market, collected, was, to, a, and"
19051,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.122137405,"early, with, the, huanan, and, for, of, a, to, team, there, no, in, animal, at, market"
19052,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.122137405,"for, and, with, to, at, the, huanan, market, in, early, of, team, a, there, no, animal"
19053,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.12195122,"in, a, of, “the, presence, large, reservoir, viruses, horseshoe, bats"
19054,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.12195122,"other, coronaviruses, which, to, and"
19055,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.12195122,"sars-cov-2, sars-cov, and, to, bat"
19056,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.12195122,"the, natural, of, from, and"
19057,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.12195122,"the, in, as, two, from"
19058,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.12195122,"the, to, bats, of, be"
19059,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.12195122,"genetic, have, in, and, to"
19060,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.12195122,"similar, to, bat, sars-cov, sars-cov-2."
19061,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.12195122,"to, and, similar, in, bat"
19062,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.12195122,"of, sars-cov-2, in, and, to"
19063,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.12195122,"of, and, which, in, sars-cov-2"
19064,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.12195122,"of, sars-cov-2, more, to, than"
19065,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.12195122,"of, and, more, from, bats"
19066,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.12195122,"such, in, to, sars-cov-2, is"
19067,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.12195122,"that, sars-cov-2, a, origin, of"
19068,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.12195122,"many, and, that, a, within"
19069,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.12195122,"the, viruses, are, to, of"
19070,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.12195122,"that, are, the, to, bat"
19071,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.12195122,"to, bat, that, the, sars-cov-2"
19072,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.12195122,"that, the, belongs, to, bat"
19073,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.12195122,"that, sars-cov-2, genome, to, the"
19074,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.12195122,"to, the, of, a, bat"
19075,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.12195122,"the, virus, to, sars-cov-2, covid-19"
19076,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.12195122,"sars-cov-2, is, to, bat, the"
19077,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.12195122,"and, can, be, to, humans"
19078,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.12195122,"a, the, that, in, human"
19079,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.12195122,"the, as, a, that, has"
19080,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.12195122,"a, that, the, in, its"
19081,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.12195122,"the, that, has, scale, of"
19082,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.12195122,"the, zoonotic, and, bats, of"
19083,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.12195122,"most, of, the, have, been"
19084,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.12195122,"in, the, that, a, human"
19085,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.12195122,"is, that, the, had, to"
19086,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.12195122,"to, a, in, the, human"
19087,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.12195122,"the, similarity, to, is, that"
19088,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.12195122,"the, sequence, to, and, in"
19089,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.12195122,"the, from, bats, to, humans,"
19090,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.12195122,"the, from, phylogenetic, to, humans,"
19091,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.12195122,"bats, the, hosts, for, sars-cov-2"
19092,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.12195122,"that, were, the, this, is"
19093,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.12195122,"in, to, were, seafood, market"
19094,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.12195122,"coronavirus, and, the, of, animal"
19095,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.12195122,"the, of, to, a, and"
19096,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.12195122,"to, and, a, the, is"
19097,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.12195122,"is, the, be, and, sars-cov-2"
19098,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.12195122,"sars-cov-2, is, a, to, the"
19099,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.12195122,"the, of, is, to, sars-cov-2"
19100,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.12195122,"of, has, been, that, the"
19101,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.12195122,"that, bats, are, the, most"
19102,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.12195122,"the, and, bats, be, hosts"
19103,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.12195122,"are, of, the, bats, and"
19104,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.12195122,"the, to, with, a, high"
19105,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.12195122,"and, to, coronaviruses, which, other"
19106,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.12195122,"the, and, of, coronaviruses, to"
19107,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.12195122,"the, of, coronaviruses, and, which"
19108,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.12195122,"was, the, and, to, sars-cov"
19109,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.12195122,"bat, is, the, sars-cov-2, that"
19110,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.12195122,"sars-cov, and, sars-cov-2, to, bat"
19111,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.12195122,"and, that, the, bat, of"
19112,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.12195122,"the, of, bats, natural, for"
19113,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.12195122,"the, sars-cov-2, and, of, to"
19114,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.12195122,"bats, of, to, be, the"
19115,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.12195122,"a, in, the, which, that"
19116,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.12195122,"the, that, a, in, originated"
19117,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.12195122,"other, that, a, hypothesis, the"
19118,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.12195122,"the, hypothesis, that, a, of"
19119,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.12195122,"the, to, as, of, sars-cov-2"
19120,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.12195122,"that, the, to, humans, of"
19121,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.12195122,"that, as, to, sars-cov-2, humans"
19122,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.12195122,"to, the, of, from, a"
19123,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.12195122,"that, the, genomic, and, only"
19124,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.12195122,"the, that, are, sars-cov-2, and"
19125,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.12195122,"the, that, sars-cov-2, has, and"
19126,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.12195122,"that, wuhan, the, was, not"
19127,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.12195122,"phylogenetic, of, the, that, and"
19128,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.12195122,"the, of, that, was, hypothesis"
19129,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.12195122,"the, of, sars-cov-2, from, at"
19130,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.12195122,"are, the, from, to, a"
19131,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.12195122,"that, the, of, a, bat"
19132,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.12195122,"a, of, bat, from, sars-cov-2"
19133,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.12195122,"at, the, of, sars-cov-2, from"
19134,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.12195122,"from, of, sars-cov-2, the, humans"
19135,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.12195122,"that, sars-cov-2, to, be, the"
19136,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.12195122,"the, that, sars-cov-2, through, and"
19137,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.12195122,"the, in, and, of, 2019"
19138,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.12195122,"of, the, huanan, market, by"
19139,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.12195122,"the, presence, of, was, virus"
19140,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.12195122,"of, animal, coronavirus, and, the"
19141,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.12195122,"most, of, the, been, in"
19142,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.12195122,"huanan, in, the, was, and"
19143,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.12195122,"the, in, that, sars-cov-2, was"
19144,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.12195122,"the, in, and, that, sars-cov-2"
19145,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.12195122,"that, the, sars-cov-2, and, than"
19146,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.12195122,"sars-cov-2, and, in, zoonotic, humans"
19147,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.12195122,"other, that, sars-cov-2, from, a"
19148,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.12195122,"a, that, the, in, sars-cov-2"
19149,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.12195122,"the, in, that, sars-cov-2, a"
19150,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.12195122,"in, their, evidence, sars-cov-2, is"
19151,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.12195122,"sars-cov-2, were, at, the, market."
19152,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.12195122,"the, two, as, from, in"
19153,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.12195122,"that, market, in, the, it"
19154,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.12195122,"that, from, a, in, to"
19155,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.12195122,"the, that, has, as, a"
19156,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.12195122,"as, to, the, a, bat"
19157,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.12195122,"the, that, were, is, this"
19158,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.12195122,"the, from, that, also, and"
19159,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.12195122,"species, of, to, and, infection"
19160,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.12195122,"a, that, to, infect, and"
19161,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.12195122,"of, a, that, to, and"
19162,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.12195122,"that, to, and, a, of"
19163,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.12195122,"have, human, from, in, and"
19164,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.12195122,"the, genome, that, and, a"
19165,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.12195122,"the, was, and, that, a"
19166,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.12195122,"that, the, covid-19, and, to"
19167,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.12195122,"the, of, to, be, possible"
19168,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.12195122,"with, the, of, bats, a"
19169,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.12195122,"of, a, possible, in, the"
19170,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.12195122,"to, the, high, with, a"
19171,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.12195122,"the, high, of, to, in"
19172,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.12195122,"center, and, with, to, the, huanan, market, in, of, a"
19173,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.12195122,"of, the, cases, in, that"
19174,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.12195122,"the, market, that, in, of, cases, exposed, to, who, had"
19175,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.12195122,"that, horseshoe, virus, has, of"
19176,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.12195122,"that, pangolin, and, the, virus"
19177,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Bats have been reported as being the rich source of 

coronaviruses",0.12195122,"the, have, as, source, of"
19178,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.12195122,"have, the, similarity, sars-cov-2, to"
19179,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.12195122,"from, sars-cov-2, with, 99%, similarity"
19180,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.12195122,"of, their, and, to, the"
19181,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.12195122,"analysis, that, sars-cov-2, to, the"
19182,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.12195122,"that, the, a, to, and"
19183,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.12195122,"a, of, sars-cov-2, by, the"
19184,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.12195122,"the, of, and, is, to"
19185,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.12195122,"the, that, an, animal, of"
19186,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.12195122,"transmitted, to, humans, an, animal"
19187,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.12195122,"to, humans,, the, from, bats"
19188,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.12195122,"a, are, to, the, from"
19189,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.12195122,"in, wuhan,, the, was, and"
19190,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.12195122,"the, in, from, market, was"
19191,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.12195122,"the, in, to, was, virus"
19192,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.12195122,"a, in, bats, the, china"
19193,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.12195122,"a, the, virus, to, and"
19194,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.12195122,"are, to, and, a, the"
19195,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.12195122,"in, have, genetic, to, and"
19196,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.12195122,"of, the, covid-19, to, that"
19197,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.12195122,"is, a, virus, that, the"
19198,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.12195122,"that, and, in, who, were"
19199,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.12195122,"the, in, that, more, likely"
19200,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.12195122,"that, to, and, the, origin"
19201,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.12195122,"is, and, that, to, animal"
19202,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.12195122,"virus, in, is, similar, the"
19203,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.12195122,"the, huanan, was, in, and"
19204,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.12195122,"and, the, was, in, wuhan,"
19205,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.12195122,"bats, the, of, and, zoonotic"
19206,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.12195122,"that, the, of, to, and"
19207,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.12195122,"of, to, the, that, virus"
19208,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.12195122,"is, that, the, be, and"
19209,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.12195122,"is, virus, that, to, the"
19210,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.12195122,"the, is, to, be, intermediate"
19211,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.12195122,"the, have, been, in, animals"
19212,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.12195122,"the, have, been, in, from"
19213,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.12195122,"the, that, to, be, sars-cov-2"
19214,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.12195122,"analysis, to, that, sars-cov-2, the"
19215,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.12195122,"analysis, the, sars-cov-2, that, revealed"
19216,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.12195122,"that, not, the, was, wuhan"
19217,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.12195122,"the, that, in, it, market"
19218,"Bats have been reported as being the rich source of 

coronaviruses","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.12195122,"have, as, the, source, of"
19219,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.12195122,"the, showed, suggesting, that, from"
19220,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.12195122,"to, sars-cov-2, has, the, of"
19221,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.12195122,"the, sars-cov, was, and, to"
19222,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.12195122,"sars-cov-2, to, ace2, receptor, host"
19223,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.12195122,"the, was, to, by, a"
19224,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.12195122,"bat, similar, to, sars-cov, sars-cov-2."
19225,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.12195122,"the, to, have, similarity, sars-cov-2"
19226,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.12195122,"is, that, several, of, the"
19227,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.12195122,"sars-cov-2, virus, between, the, and"
19228,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.12195122,"in, from, of, the, those"
19229,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.12195122,"a, of, in, the, as"
19230,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.12195122,"of, the, in, a, viruses"
19231,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.12195122,"are, pangolin, a, the, of"
19232,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.12195122,"the, first, to, it, animals"
19233,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.12195122,"bats, to, genetically, related, are"
19234,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.12195122,"related, bat, to, sars-cov-2, the"
19235,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.12195122,"the, of, to, is, also"
19236,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.12195122,"human, have, in, and, from"
19237,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.12195122,"to, virus, been, and, the"
19238,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.12195122,"sars-cov-2, is, a, natural, that"
19239,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.12195122,"the, sars-cov-2, from, is, and"
19240,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.12195122,"the, that, sars-cov-2, from, animal"
19241,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.12195122,"is, to, and, that, animal"
19242,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.12195122,"that, an, animal, be, of"
19243,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.12195122,"that, more, likely, of, sars-cov-2"
19244,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.12195122,"of, the, sequence, ratg13,, and"
19245,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.12195122,"genome, from, the, of, virus"
19246,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.12195122,"the, of, that, to, is"
19247,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.12195122,"approximately, of, the, human, with"
19248,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.12195122,"revealed, that, the, and, bat"
19249,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.12195122,"virus, that, identity, the, bat"
19250,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.12195122,"the, of, to, bat, that"
19251,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.12195122,"the, of, identity, to, that"
19252,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.12195122,"through, the, that, sars-cov-2, and"
19253,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.12195122,"other, a, that, sars-cov-2, from"
19254,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.12195122,"the, originated, from, and, a"
19255,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.12195122,"sars-cov-2, ace2, receptor, to, host"
19256,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.12195122,"genomic, that, only, and, the"
19257,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.12195122,"and, revealed, that, the, bat"
19258,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.12195122,"(ratg13), that, genomic, the, bat"
19259,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.12195122,"that, in, from, a, to"
19260,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.12195122,"from, the, market, that, in"
19261,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.12195122,"the, and, transmitted, hosts, of"
19262,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.12195122,"who, were, that, in, and"
19263,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.12195122,"is, a, bat, in, from"
19264,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.12195122,"analysis, revealed, that, sars-cov-2, the"
19265,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.12195122,"a, of, sars-cov-2, genome, the"
19266,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.12195122,"bats, intermediate, pangolins, may, the"
19267,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Bats are natural hosts of many of the known  

coronaviruses",0.12195122,"the, of, bats, hosts, are"
19268,"This suggests that the BANAL series may be able to directly infect  

humans.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.12195122,"this, that, the, may, to"
19269,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.12195122,"to, the, is, be, intermediate"
19270,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.12195122,"that, a, virus, has, of"
19271,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.12195122,"the, of, that, to, in"
19272,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.12195122,"of, the, in, to, with"
19273,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.12195122,"the, that, to, a, coronavirus"
19274,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.12195122,"a, of, be, that, may"
19275,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.12195122,"the, sars-cov-2, to, bats, of"
19276,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.12195122,"the, of, was, and, to"
19277,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.12195122,"the, bat, isolated, from, in"
19278,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.12195122,"the, of, that, an, animal"
19279,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.12195122,"that, of, an, animal, be"
19280,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.12195122,"and, a, between, sars-cov-2, receptor"
19281,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.12195122,"many, within, and, a, that"
19282,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.12195122,"the, and, that, was, a"
19283,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.12195122,"and, from, of, natural, the"
19284,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.12195122,"the, of, sars-cov-2, and, between"
19285,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.12195122,"a, was, the, to, by"
19286,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.12195122,"as, the, viruses, of, and"
19287,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.12195122,"of, the, been, in, and"
19288,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.12195122,"to, are, related, genetically, bats"
19289,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.12195122,"the, in, and, for, of"
19290,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.12195122,"recent, wild, to, sars-cov-2, in"
19291,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.12195122,"the, of, sars-cov-2, and, viruses"
19292,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.12195122,"of, the, bats, natural, for"
19293,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.12195122,"a, the, of, with, bats"
19294,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.12195122,"the, of, to, a, bat"
19295,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.12195122,"the, of, as, a, human"
19296,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.12195122,"the, as, a, bat, to"
19297,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.12195122,"the, of, to, bat, as"
19298,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.12195122,"is, the, to, that, had"
19299,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.12195122,"to, no, had, the, sars-cov-2"
19300,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.12195122,"was, the, genome, sars-cov-2, to"
19301,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.12195122,"the, virus, was, and, to"
19302,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.12195122,"the, virus, been, to, and"
19303,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.12195122,"no, the, had, to, sars-cov-2"
19304,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.12195122,"the, sars-cov-2, virus, and, to"
19305,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.12195122,"to, is, that, related, in"
19306,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.12195122,"and, sars-cov-2, in, of, which"
19307,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.12195122,"coronaviruses, the, which, of, and"
19308,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.12195122,"in, genome, of, with, sars-cov-2"
19309,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.12195122,"virus, has, that, of, horseshoe"
19310,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.12195122,"that, virus, a, of, has"
19311,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.12195122,"of, in, with, sars-cov-2, genome"
19312,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.12195122,"of, sars-cov-2, a, virus, in"
19313,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.12195122,"that, virus, found, in, with"
19314,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.12195122,"the, sars-cov-2, to, is, that"
19315,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.12195122,"that, similar, to, the, sars-cov-2"
19316,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.12195122,"the, virus, to, from, market"
19317,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.12195122,"the, from, market, to, with"
19318,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.12195122,"the, of, that, by, a"
19319,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.12195122,"that, a, the, origin, of"
19320,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.12195122,"phylogenetic, and, that, the, of"
19321,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.12195122,"sars-cov-2, is, that, and, the"
19322,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.12195122,"of, the, sequence, and, ratg13,"
19323,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.12195122,"sequence, ratg13,, that, and, sars-cov-2"
19324,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.12195122,"the, of, in, to, high"
19325,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.12195122,"sars-cov-2, ratg13, to, the, in"
19326,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.12195122,"in, the, of, to, sars-cov-2"
19327,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.12195122,"the, from, an, as, to"
19328,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.12195122,"the, of, sars-cov-2, humans, from"
19329,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.12195122,"of, the, those, in, from"
19330,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.12195122,"sequence, coronavirus,, ratg13,, from, bat"
19331,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.12195122,"amino, acid, the, rbd, sars-cov-2"
19332,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.12195122,"by, in, the, with, not"
19333,"S1/S2 cleavage sites of coronaviruses are frequently modi- 

fied by insertions or deletions (indels) during evolution","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.12195122,"s1/s2, cleavage, sites, coronaviruses, by"
19334,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.12195122,"a, the, to, in, human"
19335,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.12195122,"sars-cov-2, in, the, same, with"
19336,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.12195122,"a, that, infect, to, and"
19337,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.12195122,"that, to, the, and, was"
19338,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.12195122,"the, rbd, amino, acid, sars-cov-2"
19339,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.12195122,"the, possible, to, be, of"
19340,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.12195122,"the, of, is, also, to"
19341,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.12195122,"for, and, to, the, of"
19342,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.12195122,"is, the, and, for, sars-cov-2"
19343,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.12195122,"to, the, from, as, an"
19344,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.12195122,"were, to, seafood, market, in"
19345,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.12195122,"of, the, approximately, with, human"
19346,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.12195122,"in, the, with, to, of"
19347,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.12195122,"the, of, with, to, human"
19348,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.12195122,"the, market., sars-cov-2, were, at"
19349,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.12195122,"the, sars-cov-2, to, species, and"
19350,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.12195122,"the, was, from, market, in"
19351,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.12195122,"that, the, from, market, in"
19352,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.12195122,"the, in, that, for, of"
19353,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.12195122,"a, virus, in, of, sars-cov-2"
19354,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.12195122,"is, a, sars-cov-2, to, or"
19355,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.12195122,"is, the, sars-cov-2, to, a"
19356,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.12195122,"natural, in, the, virus, of"
19357,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.12195122,"and, species, in, the, of"
19358,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.12195122,"sars-cov-2, including, the, coronaviruses, of"
19359,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.12195122,"the, of, and, as, viruses"
19360,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.12195122,"to, the, sars-cov-2, as, of"
19361,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.12195122,"bats, the, reservoir, of, and"
19362,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.12195122,"that, the, sars-cov-2, to, bat"
19363,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.12195122,"that, sars-cov-2, and, are, the"
19364,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.12195122,"the, that, bat, and, to"
19365,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.12195122,"and, that, the, to, bat"
19366,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.12195122,"that, the, to, sars-cov-2, coronaviruses"
19367,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.12195122,"that, sars-cov-2, bat, to, in"
19368,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.12195122,"the, that, sars-cov-2, and, to"
19369,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.12195122,"the, species, of, in, and"
19370,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.12195122,"a, in, the, of, possible"
19371,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.12195122,"the, of, to, bat, is, that, bats, as, for, its"
19372,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.12195122,"sars-cov-2, closest, with, of, to"
19373,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.12195122,"of, to, sars-cov-2,, sars-cov-2, from"
19374,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.12195122,"sars-cov-2, to, related, bat, the"
19375,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.12195122,"the, viruses, are, of, to"
19376,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.12195122,"that, and, are, the, of"
19377,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.12195122,"to, is, that, and, the"
19378,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.12195122,"are, and, the, that, to"
19379,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.12195122,"the, of, that, are, to"
19380,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.12195122,"of, the, human, to, with"
19381,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.12195122,"with, the, of, that, scientists"
19382,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","This suggests that the BANAL series may be able to directly infect  

humans.",0.12195122,"the, that, may, to, this"
19383,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.12195122,"the, of, sars-cov-, from, more"
19384,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.12195122,"of, the, in, from, is"
19385,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.12195122,"virus, the, covid-19, to, sars-cov-2"
19386,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.12195122,"the, sars-cov-2, to, be, is"
19387,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.12195122,"to, sars-cov-2, the, virus, be"
19388,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.12195122,"covid-19, be, in, the, sars-cov-2"
19389,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.12195122,"sars-cov-2, is, be, and, the"
19390,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.12195122,"is, that, the, and, be"
19391,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.12195122,"that, the, covid-19, is, and"
19392,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.12195122,"“the, presence, of, a, large, reservoir, viruses, in, horseshoe, bats"
19393,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.12195122,"the, of, in, center, to, with, a, and, huanan, market"
19394,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.12195122,"of, cases, to, the, market, who, in, that, had, exposed"
19395,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.12195122,"a, natural, origin, and, zoonotic"
19396,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.12195122,"a, and, in, animal, zoonotic"
19397,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.12195122,"this, that, in, and, the"
19398,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.12195122,"a, zoonotic, are, the, and"
19399,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.12195122,"sars-cov-2, is, to, a, the"
19400,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.12195122,"is, that, the, virus, a"
19401,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.12195122,"is, that, the, virus, to"
19402,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.12195122,"that, sars-cov-2, a, natural, is"
19403,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","expended to make the simple point 

that COVID-19 had a natural origin.",0.12195122,"the, covid-19, a, to, that"
19404,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","expended to make the simple point 

that COVID-19 had a natural origin.",0.12195122,"the, to, natural, a, that"
19405,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.12195122,"to, and, their, the, of"
19406,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.12195122,"the, a, in, to, and"
19407,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.12195122,"zoonotic, sars-cov-2, humans, in, and"
19408,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.12195122,"and, a, natural, zoonotic, origin"
19409,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.12195122,"animal, a, zoonotic, and, in"
19410,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.12195122,"sars-cov-2, a, has, in, animal"
19411,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.12195122,"in, the, that, its, a"
19412,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.12195122,"that, the, virus, identity, bat"
19413,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.12195122,"that, the, genomic, bat, (ratg13)"
19414,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.12195122,"sars-cov-2, related, that, of, is"
19415,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.12195122,"a, of, sars-cov-2, coronavirus, that"
19416,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.12195122,"is, the, to, that, similarity"
19417,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.12195122,"that, the, to, of, bat"
19418,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.12195122,"as, to, the, of, bat"
19419,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.12195122,"the, of, bat, to, as, bats, that, for, is, its"
19420,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.12195122,"the, to, for, is, likely"
19421,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.12195122,"the, that, of, similarity, to"
19422,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.12195122,"the, of, to, that, bats"
19423,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.12195122,"the, which, a, that, in"
19424,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.12195122,"suggests, that, the, is, a"
19425,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.12195122,"the, that, of, by, a"
19426,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.12195122,"evolutionary, of, that, the, and"
19427,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.12195122,"of, that, it, is, the"
19428,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.12195122,"presence, of, virus, the, was"
19429,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.12195122,"the, virus, was, to, in"
19430,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.12195122,"more, from, sars-cov-, the, of"
19431,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.12195122,"recombination, and, the, of, sars-cov-2"
19432,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.12195122,"the, of, coronaviruses, including, sars-cov-2"
19433,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.12195122,"is, that, sars-cov-2, of, related"
19434,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.12195122,"a, bat, that, the, of"
19435,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.12195122,"that, a, of, the, most"
19436,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.12195122,"that, genome, a, the, of"
19437,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.12195122,"the, to, in, sequence, and"
19438,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.12195122,"phylogenetic, to, humans,, the, from"
19439,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.12195122,"to, the, that, of, humans"
19440,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.12195122,"and, of, the, in, 2019"
19441,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.12195122,"hosts, and, the, of, transmitted"
19442,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.12195122,"can, be, to, humans, and"
19443,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.12195122,"an, animal, transmitted, to, humans"
19444,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.12195122,"in, to, is, the, covid-19"
19445,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.12195122,"the, most, have, been, of"
19446,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.12195122,"in, most, been, the, of"
19447,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.12195122,"that, the, of, cases, in"
19448,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.12195122,"early, in, the, of, reported"
19449,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.12195122,"in, the, of, that, which"
19450,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.12195122,"that, the, was, to, and"
19451,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.12195122,"and, the, of, that, evolutionary"
19452,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.12195122,"it, is, that, of, the"
19453,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.12195122,"animals, in, the, have, been"
19454,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.12195122,"animals, to, the, first, it"
19455,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.12195122,"the, bats, a, in, china"
19456,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.12195122,"the, of, a, as, diversity"
19457,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.12195122,"a, of, in, china, ("
19458,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.12195122,"several, the, of, is, that"
19459,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.12195122,"the, isolated, in, from, bat"
19460,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.12195122,"in, the, and, palm, civet"
19461,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.12195122,"from, in, the, have, been"
19462,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.12195122,"is, sars-cov-2, the, and, from"
19463,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.12195122,"the, virus, is, similar, in"
19464,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.12195122,"bats, the, pangolins, may, intermediate"
19465,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.12195122,"is, that, the, covid-19, and"
19466,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.12195122,"this, is, and, the, that"
19467,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.12195122,"the, to, is, likely, for"
19468,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.12195122,"sequence, that, ratg13,, and, sars-cov-2"
19469,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.12195122,"sars-cov-2, has, been, that, a"
19470,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.12195122,"that, sars-cov-2, the, virus, of"
19471,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.12195122,"the, of, to, for, and"
19472,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.12195122,"the, in, not, with, by"
19473,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.12195122,"to, that, sars-cov-2, bat, in"
19474,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.12195122,"a, that, sars-cov-2, in, bat"
19475,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.12195122,"to, sars-cov-2, is, a, that"
19476,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.12195122,"is, sars-cov-2, or, to, a"
19477,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.12195122,"sars-cov-2, is, to, host, or"
19478,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.12195122,"scientists, that, the, of, with"
19479,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.12195122,"to, that, sars-cov-2, as, humans"
19480,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.12195122,"recent, sars-cov-2, to, in, wild"
19481,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.12195122,"has, been, that, sars-cov-2, a"
19482,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.12195122,"that, the, of, most, a"
19483,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.12195122,"a, diversity, of, the, as"
19484,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.12195122,"such, is, to, sars-cov-2, in"
19485,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.12195122,"is, evidence, sars-cov-2, in, their"
19486,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.12195122,"from, a, is, in, bat"
19487,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.12195122,"are, viruses, to, and, that"
19488,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.12195122,"that, is, to, be, from"
19489,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.12195122,"to, the, of, rbd, bind"
19490,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.12195122,"is, that, the, most, to"
19491,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.12195122,"the, sars-cov-2, bats, hosts, for"
19492,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.12195122,"studies, that, sars-cov-2, on, the"
19493,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.12195122,"that, from, the, and, also"
19494,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.12195122,"a, coronavirus, the, that, to"
19495,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.12195122,"that, the, more, likely, bats"
19496,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.12195122,"the, are, bat, that, to"
19497,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.12195122,"the, is, sars-cov-2, to, a"
19498,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.12195122,"are, a, the, that, to"
19499,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.12195122,"to, that, the, most, is"
19500,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.12195122,"the, reservoir, is, it, to"
19501,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.12195122,"that, belongs, to, bat, the"
19502,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.12195122,"the, sars-cov-2, a, of, origin"
19503,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.12195122,"a, of, the, sars-cov-2, genome"
19504,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.12195122,"from, bat, coronavirus,, ratg13,, sequence"
19505,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.12195122,"in, yunnan, was, to, of"
19506,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.12195122,"receptor, a, between, sars-cov-2, and"
19507,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.12195122,"have, been, to, the, sars-cov-2"
19508,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.12195122,"the, of, sars-cov-2, is, that"
19509,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.12195122,"bats, be, the, hosts, and"
19510,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.12195122,"we, for, that, the, sars-cov-2"
19511,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.12195122,"more, from, bats, of, and"
19512,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.12195122,"sars-cov-2, the, viruses, and, of"
19513,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.12195122,"the, that, bats, more, likely"
19514,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.12195122,"sars-cov-2, is, to, and, the"
19515,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.12195122,"this, that, the, is, and"
19516,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.12195122,"the, same, sars-cov-2, in, with"
19517,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.12195122,"is, host, sars-cov-2, to, or"
19518,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.12195122,"the, sars-cov-2, bat, or, pangolin"
19519,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.12195122,"the, more, likely, that, in"
19520,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.12195122,"the, sars-cov-2, than, that, and"
19521,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.12195122,"that, is, the, bat, and"
19522,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.12195122,"more, likely, that, of, sars-cov-2"
19523,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.12195122,"the, sequences, of, and, sars-cov-2"
19524,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.12195122,"this, the, of, origin, and"
19525,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.12195122,"sars-cov-2, the, bat, or, pangolin"
19526,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.12195122,"from, genome, the, of, virus"
19527,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.12195122,"of, the, early, reported, in"
19528,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.12195122,"that, sars-cov-2, to, genome, the"
19529,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.12195122,"a, hypothesis, that, the, other"
19530,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.12195122,"are, and, the, to, a"
19531,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.12195122,"the, origin, to, that, and"
19532,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.12195122,"of, the, are, a, pangolin"
19533,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.12195122,"that, the, of, genome, a"
19534,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.12195122,"that, the, sars-cov-2, on, studies"
19535,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.12195122,"sars-cov-2, to, of, more, than"
19536,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.12195122,"the, sars-cov-2, same, and, is"
19537,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.12195122,"the, sars-cov-2, and, of, is"
19538,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.12195122,"the, of, and, sars-cov-2, recombination"
19539,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.12195122,"of, the, sars-cov-2, in, and"
19540,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.12195122,"the, sars-cov-2, we, that, for"
19541,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.12195122,"in, the, that, sars-cov-2, for"
19542,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.12195122,"evidence, that, pangolin-cov, the, of"
19543,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.12195122,"the, originated, and, from, a"
19544,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.12195122,"the, from, a, in, and"
19545,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.12195122,"and, in, the, palm, civet"
19546,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.12195122,"the, bats, reservoir, of, and"
19547,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.12195122,"from, 99%, similarity, with, sars-cov-2"
19548,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.12195122,"the, sars-cov-2, is, for, and"
19549,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.12195122,"is, the, with, sars-cov-2, for"
19550,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.12195122,"are, to, the, in, and"
19551,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.12195122,"the, virus, that, of, and"
19552,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.12195122,"virus, that, and, the, pangolin"
19553,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.12195122,"the, that, virus, of, and"
19554,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.12195122,"the, of, natural, virus, in"
19555,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.12195122,"and, this, in, the, that"
19556,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.12195122,"the, of, that, has, scale"
19557,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.12195122,"to, virus, and, the, sars-cov-2"
19558,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.12195122,"the, to, that, sars-cov-2, and"
19559,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.12195122,"closest, to, of, with, sars-cov-2"
19560,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.12195122,"the, similarity, of, to, that"
19561,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.12195122,"the, in, and, that, of"
19562,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.12195122,"the, from, showed, suggesting, that"
19563,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.12195122,"that, the, identity, to, of"
19564,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.12195122,"to, sars-cov-2,, of, from, sars-cov-2"
19565,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.12195122,"of, the, in, that, which"
19566,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.12195122,"the, virus, to, sars-cov-2, be"
19567,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.12195122,"to, the, a, of, from"
19568,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.12195122,"rbd, of, to, bind, the"
19569,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.12195122,"is, to, that, from, be"
19570,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.12195122,"the, be, between, and, sars-cov-2"
19571,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.12195122,"the, between, sars-cov-2, and, virus"
19572,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.12195122,"sars-cov-2, has, a, in, animal"
19573,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.12195122,"that, sars-cov-2, the, from, animal"
19574,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.12195122,"the, sars-cov-2, be, in, covid-19"
19575,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.12195122,"it, is, the, reservoir, to"
19576,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.12195122,"a, bat, of, sars-cov-2, from"
19577,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.12195122,"the, and, a, zoonotic, origin"
19578,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.12195122,"are, a, zoonotic, and, the"
19579,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.12195122,"that, may, be, a, of"
19580,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.12195122,"and, in, to, related, that, of, bats, are, natural, hosts"
19581,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.12195122,"that, the, of, was, to"
19582,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.12195122,"of, to, was, in, yunnan"
19583,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.12195122,"bats, are, natural, hosts, of, and, related, to, that, in"
19584,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.12195122,"of, is, to, the, bat"
19585,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.12195122,"in, bat, similar, to, and"
19586,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.12195122,"that, is, in, related, to"
19587,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.12195122,"evidence, pangolin-cov, that, the, of"
19588,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.12195122,"more, than, of, the, to"
19589,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.12195122,"a, that, the, sars-cov-2, is"
19590,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.12195122,"a, is, the, suggests, that"
19591,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.12173913,"and, at, the, it, would, that, or, its, was, of, sars-cov-2, into, in, by"
19592,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.12173913,"its, into, and, it, to, was, not, by, the, of, that, sars-cov-2, have, in"
19593,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.12173913,"the, of, that, virus, into, a, in, human, sars, this, or, humans, with, to"
19594,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.12173913,"this, that, sars, a, the, virus, into, humans, human, or, with, of, in, to"
19595,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.12173913,"the, that, was, in, by, its, of, or, it, and, would, into, sars-cov-2, at"
19596,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.12173913,"the, that, was, to, have, in, by, its, of, it, and, not, into, sars-cov-2"
19597,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.121621622,"intermediate, hosts,, such, as, and, possibility, of, that, in"
19598,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.121621622,"to, that, the, of, bats, and, as, for, are"
19599,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.121621622,"the, analysis, of, have, that, is, was, transmitted, to"
19600,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.121621622,"have, that, the, virus, in, to, from, a, market"
19601,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.121621622,"of, to, have, the, that, was, transmitted, analysis, is"
19602,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.121621622,"and, to, was, by, the, of, that, sars-cov-2, have"
19603,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.121621622,"in, a, to, have, the, virus, that, from, market"
19604,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.121621622,"the, and, that, virus, from, a, in, humans, to"
19605,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.121621622,"to, could, recombination, of, bats, the, and, suggested, with"
19606,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.121621622,"viruses, similar, to, the, in, of, and, that, a"
19607,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.121621622,"coronaviruses, in, are, to, that, of, and, sequences, ratg13"
19608,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.121621622,"can, be, a, from, bat, to, bats, and, as"
19609,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.121621622,"wuhan, to, at, the, huanan, seafood, market, in, on"
19610,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.121621622,"the, huanan, market, is, wuhan, have, in, to, covid-19"
19611,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.121621622,"as, the, to, species, have, high, and, which, viruses"
19612,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.121621622,"from, its, as, and, it, for, the, of, a"
19613,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.121621622,"to, the, coronavirus, 2, in, bats, of, that, a"
19614,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.121621622,"suggested, bats, the, recombination, to, with, of, could, and"
19615,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.121621622,"have, the, to, high, and, which, species, as, viruses"
19616,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.121621622,"that, the, virus, in, and, to, humans, from, a"
19617,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.121621622,"to, at, the, huanan, seafood, market, in, wuhan, on"
19618,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.121621622,"covid-19, is, to, have, the, huanan, market, in, wuhan"
19619,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.121621622,"in, these, are, and, all, with, that, the, is"
19620,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.121621622,"the, of, and, that, a, in, viruses, similar, to"
19621,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.121621622,"that, of, bats, to, a, coronavirus, in, the, 2"
19622,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.121621622,"the, and, a, in, to, suggesting, that, these, of"
19623,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.121621622,"a, and, from, bat, can, be, as, to, bats"
19624,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.121621622,"and, that, of, in, possibility, intermediate, hosts,, such, as"
19625,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.121621622,"the, of, and, have, that, sars-cov-2, was, to, by"
19626,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.121621622,"the, of, as, a, for, it, its, from, and"
19627,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.121621622,"of, and, coronaviruses, that, sequences, in, ratg13, are, to"
19628,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.121621622,"this, to, that, natural, the, of, origin, and, be"
19629,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.121621622,"that, the, to, be, this, of, natural, origin, and"
19630,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.121621622,"the, is, that, are, with, and, these, in, all"
19631,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.121621622,"bats, are, for, as, the, of, and, that, to"
19632,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.121621622,"to, the, in, of, and, suggesting, that, these, a"
19633,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.121495327,"in, the, health, animals, from, that, for, at, was, to, a, coronavirus, and"
19634,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.121495327,"in, the, animals, live, animal, of, from, positive, chinese, market, indicated, a, and"
19635,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.121495327,"in, may, the, animals, of, from, that, only, two, also, to, different, a"
19636,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.121495327,"in, the, a, coronavirus, was, that, from, animals, to, at, and, for, health"
19637,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.121495327,"in, chinese, the, market, live, positive, from, animal, and, a, indicated, of, animals"
19638,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.121495327,"from, in, also, two, different, only, the, of, that, a, animals, may, to"
19639,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.121212121,"viruses, in, horseshoe, bats"
19640,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.121212121,"a, horseshoe, in, of"
19641,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.121212121,"bat, to, sars-cov-2, pangolin"
19642,"this one jumped from bats origin  

into humans","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.121212121,"this, from, into, humans"
19643,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.121212121,"a, of, in, coronaviruses"
19644,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.121212121,"from, or, in, the"
19645,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.121212121,"coronaviruses, have, to, and"
19646,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.121212121,"of, in, to, bats"
19647,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.121212121,"to, sars-cov-2, and, in"
19648,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.121212121,"and, in, of, sars-cov-2"
19649,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.121212121,"the, sars, and, to"
19650,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.121212121,"is, to, in, virus"
19651,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.121212121,"to, virus, genome, sars-cov-2"
19652,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.121212121,"virus, sars-cov-2, in, its"
19653,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.121212121,"in, of, bats, the"
19654,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.121212121,"the, in, of, also"
19655,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.121212121,"the, in, bats, are"
19656,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.121212121,"are, also, the, of"
19657,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.121212121,"the, and, which, have, to, of, bat, human"
19658,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.121212121,"sars-cov, and, to, the, of, human, with, palm"
19659,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.121212121,"that, be, origin, of"
19660,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.121212121,"that, origin, of, sars-cov-2"
19661,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.121212121,"could, have, been, from"
19662,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.121212121,"to, have, the, of, and, which, bat, human"
19663,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.121212121,"the, of, sars-cov-2, spike, to, human, is, a"
19664,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.121212121,"have, a, recombination, of, to, and, the, sars-cov-2"
19665,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.121212121,"that, sars-cov-2, and, with"
19666,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.121212121,"sars-cov-2, is, with, and"
19667,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.121212121,"sars-cov-2, a, virus, and"
19668,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.121212121,"the, host, as, to"
19669,"The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.121212121,"the, that, with, several"
19670,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.121212121,"has, natural, origin, and"
19671,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.121212121,"bat, host, of, and"
19672,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.121212121,"the, a, of, natural"
19673,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.121212121,"a, and, of, the"
19674,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.121212121,"a, of, the, and"
19675,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.121212121,"the, viruses, and, of"
19676,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.121212121,"of, many, and, which, that, in, such, as"
19677,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.121212121,"covs, in, and, to"
19678,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.121212121,"virus, is, to, in"
19679,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.121212121,"bats, the, hosts, of"
19680,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.121212121,"to, a, animal, and"
19681,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.121212121,"a, and, in, animal"
19682,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.121212121,"to, a, and, animal"
19683,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.121212121,"of, the, coronavirus, and"
19684,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.121212121,"transmission, an, animal, the"
19685,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.121212121,"the, bats, of, and"
19686,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.121212121,"the, bats, and, of"
19687,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.121212121,"from, the, sequence, with"
19688,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.121212121,"the, is, isolated, from"
19689,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.121212121,"the, species, barrier, and"
19690,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.121212121,"species, to, and, the"
19691,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.121212121,"the, animals, to, and"
19692,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.121212121,"geographic, and, the, in"
19693,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.121212121,"the, to, and, was"
19694,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.121212121,"to, the, in, and"
19695,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.121212121,"in, the, bats,, and"
19696,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.121212121,"the, emerged, humans, from"
19697,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.121212121,"was, the, in, animals"
19698,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.121212121,"the, sars-cov-2, bat, of"
19699,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.121212121,"96%, identity, to, and"
19700,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.121212121,"showed, that, the, of"
19701,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.121212121,"of, that, the, for"
19702,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.121212121,"the, of, natural, viral"
19703,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.121212121,"that, bats, the, for"
19704,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.121212121,"from, in, humans, the, that, a, animals, to"
19705,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.121212121,"are, that, was, to, from, and, any, in"
19706,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.121212121,"the, of, dogs, sars-cov-2"
19707,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.121212121,"the, that, a, origin"
19708,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.121212121,"in, a, that, the"
19709,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.121212121,"that, originated, in, a"
19710,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.121212121,"the, and, that, a"
19711,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.121212121,"and, the, disease, which"
19712,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.121212121,"a, the, that, and"
19713,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.121212121,"the, in, zoonotic, and"
19714,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.121212121,"that, the, a, and"
19715,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.121212121,"the, virus, that, had"
19716,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.121212121,"the, natural, of, a"
19717,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.121212121,"the, origin, a, that"
19718,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.121212121,"that, the, of, from"
19719,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.121212121,"the, that, as, origin"
19720,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.121212121,"studies, have, that, sars-cov-2"
19721,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.121212121,"such, studies, that, sars-cov-2"
19722,"Bats have been reported as being the rich source of 

coronaviruses","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.121212121,"have, being, the, of"
19723,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.121212121,"the, of, sars-cov-2, spillover"
19724,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.121212121,"that, the, was, sars-cov-2"
19725,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.121212121,"the, of, that, was"
19726,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.121212121,"the, from, bat, sars-cov-2"
19727,"This suggests that the BANAL series may be able to directly infect  

humans.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.121212121,"this, that, the, to"
19728,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.121212121,"humans, from, and, their, circulating, the, of, sars-cov-2"
19729,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.121212121,"a, origin, of, sars-cov-2, by, at, the, in"
19730,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.121212121,"that, the, of, sars-cov-2, and, this, from, viruses"
19731,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.121212121,"for, the, of, intermediate, host, into, from, humans"
19732,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.121212121,"from, into, intermediate, jumps, for, the, of, sars-cov-2"
19733,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.121212121,"the, and, to, animals"
19734,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.121212121,"to, and, be, the"
19735,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.121212121,"the, of, and, market"
19736,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.121212121,"the, that, known, be"
19737,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.121212121,"we, the, to, a"
19738,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.121212121,"a, market, in, that, the, to, closely, related"
19739,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.121212121,"in, the, a, market"
19740,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.121212121,"the, in, and, geographic"
19741,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.121212121,"the, virus, from, market"
19742,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.121212121,"a, and, animal, in"
19743,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.121212121,"a, from, with, sars-cov-2"
19744,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor",0.121212121,"possible, a, progenitor, sars-cov-2"
19745,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.121212121,"in, was, that, are, from, to, any, and"
19746,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.121212121,"that, their, in, there"
19747,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.121212121,"of, the, are, same, as, in, from, a"
19748,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.121212121,"of, virus, that, it, is, most, the, and"
19749,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.121212121,"a, that, originated, in"
19750,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.121212121,"that, the, virus, and"
19751,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.121212121,"coronaviruses, a, of, species"
19752,hese close genetic relations suggest that they all have their ecological origin in bat populations,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.121212121,"that, they, all, have"
19753,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.121212121,"there, that, in, their"
19754,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.121212121,"believed, the, as, to"
19755,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.121212121,"the, bats, a, in"
19756,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.121212121,"of, the, in, a"
19757,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.121212121,"a, study, of, in"
19758,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.121212121,"a, the, of, and, in, with, that, to"
19759,"According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.121212121,"according, to, the, sars-cov-2"
19760,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.121212121,"is, to, sars-cov-2, pangolin"
19761,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Bats have been reported as being the rich source of 

coronaviruses",0.121212121,"been, bats, the, of"
19762,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Bats have been reported as being the rich source of 

coronaviruses",0.121212121,"have, the, being, of"
19763,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.121212121,"with, the, sars-cov-2, to"
19764,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.121212121,"with, a, sars-cov-2, from"
19765,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.121212121,"the, to, coronavirus, a"
19766,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.121212121,"a, the, sars-cov-2, with"
19767,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.121212121,"sars-cov-2, shown, to, the"
19768,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.121212121,"the, from, a, malayan"
19769,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.121212121,"of, the, from, sars-cov-2, and, circulating, their, humans"
19770,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.121212121,"the, similar, to, sars-cov-2"
19771,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.121212121,"bat, the, sars-cov-2, from"
19772,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.121212121,"the, sars-cov-2, bat, ratg13"
19773,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.121212121,"has, that, the, of"
19774,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.121212121,"the, to, by, a"
19775,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.121212121,"of, the, possible, and"
19776,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.121212121,"the, of, human, and"
19777,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.121212121,"a, in, the, bats"
19778,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.121212121,"the, and, virus, humans,, from, a, in, to"
19779,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.121212121,"the, in, bats, and"
19780,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.121212121,"from, its, and, to, was, the, in, a"
19781,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.121212121,"was, that, of, the"
19782,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.121212121,"in, were, to, humans"
19783,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.121212121,"that, the, virus, had"
19784,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.121212121,"the, with, bat, and"
19785,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.121212121,"of, the, and, identity"
19786,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.121212121,"the, that, to, of"
19787,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.121212121,"that, the, of, to"
19788,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.121212121,"to, that, of, the"
19789,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.121212121,"the, with, of, natural, is, it, as, for"
19790,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.121212121,"the, from, in, or"
19791,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.121212121,"were, and, in, the"
19792,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.121212121,"to, be, related, that, the, is, bats, sars-cov-2"
19793,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.121212121,"virus, the, first, it"
19794,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.121212121,"the, that, not, virus"
19795,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.121212121,"results, that, the, be"
19796,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.121212121,"viruses, the, coronavirus, bats, of, that, a, key"
19797,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.121212121,"according, to, sars-cov-2, the"
19798,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.121212121,"the, that, of, from"
19799,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.121212121,"of, has, that, the"
19800,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.121212121,"from, the, that, of"
19801,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.121212121,",, the, of, that"
19802,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.121212121,"bat, coronaviruses, the, of"
19803,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.121212121,"studies, that, sars-cov-2, have"
19804,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.121212121,"in, a, of, the, are, from, same, as"
19805,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.121212121,"the, in, probably, virus"
19806,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.121212121,"a, to, that, from"
19807,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.121212121,"an, to, that, virus"
19808,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.121212121,"a, that, virus, to"
19809,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.121212121,"the, virus, it, first"
19810,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.121212121,"from, bats, to, the"
19811,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.121212121,"the, sars-cov-2, coronaviruses, to"
19812,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.121212121,"in, to, bats, of"
19813,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.121212121,"coronaviruses, the, to, of"
19814,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.121212121,"the, of, to, is"
19815,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.121212121,"all, have, that, they"
19816,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.121212121,"from, could, have, been"
19817,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.121212121,"have, been, to, the"
19818,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.121212121,"and, has, natural, origin"
19819,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.121212121,"the, and, is, that"
19820,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.121212121,"t, is, that, sars-cov-2"
19821,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.121212121,"that, the, and, virus"
19822,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.121212121,"from, to, bats, the"
19823,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.121212121,"appear, to, the, of"
19824,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.121212121,"that, the, and, to"
19825,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.121212121,"to, with, the, of, and, sars-cov, palm, human"
19826,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.121212121,"a, of, pangolin, with, to, and, the, intermediate"
19827,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.121212121,"of, coronavirus, and, the"
19828,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.121212121,"the, and, of, identity"
19829,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.121212121,"the, of, coronavirus, and"
19830,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.121212121,"has, the, with, bat"
19831,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.121212121,"amino, acid, sequences, of"
19832,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.121212121,"shows, identity, with, in"
19833,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.121212121,"sars-cov-2, to, in, zoonotic"
19834,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.121212121,"sars-cov-2, to, ace2, in"
19835,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.121212121,"sars-cov-2, to, receptor-binding, domain"
19836,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.121212121,"the, of, possible, and"
19837,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.121212121,"the, and, which, disease"
19838,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.121212121,"is, direct, and, the"
19839,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.121212121,"the, of, patients, and"
19840,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.121212121,"in, december, was, a, at, that, were, and"
19841,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.121212121,"a, that, in, sars-cov-2"
19842,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.121212121,"in, from, that, this"
19843,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.121212121,"that, a, virus, is"
19844,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.121212121,"a, that, virus, bat"
19845,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.121212121,"in, that, sars-cov-2, a"
19846,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.121212121,"this, in, that, sars-cov-2"
19847,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.121212121,"that, sars-cov-2, bat, is"
19848,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.121212121,"a, the, with, sars-cov-2"
19849,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.121212121,"sars-cov-2, a, the, and"
19850,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.121212121,"of, other, humans, and"
19851,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.121212121,"the, are, hosts, sars-cov-2"
19852,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.121212121,"be, the, of, intermediate"
19853,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.121212121,"a, two, and, which, both, sars-cov-2, at, the"
19854,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.121212121,"the, is, most, likely"
19855,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.121212121,"the, team, a, from"
19856,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.121212121,"coronaviruses, related, to, and"
19857,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.121212121,"the, of, that, a"
19858,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.121212121,"the, results, that, be"
19859,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.121212121,"of, sars-cov-2, the, infection"
19860,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.121212121,"the, of, with, sars-cov-2"
19861,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.121212121,"have, been, described, in"
19862,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.121212121,"be, that, origin, of"
19863,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.121212121,"and, sars-cov-2, pangolin, a"
19864,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.121212121,"sars-cov-2, a, and, pangolin"
19865,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.121212121,"that, part, of, the"
19866,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.121212121,"in, the, of, has"
19867,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.121212121,"of, sars-cov-2, the, a"
19868,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.121212121,"the, sars-cov-2, as, a"
19869,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.121212121,"a, origin, the, and"
19870,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","this one jumped from bats origin  

into humans",0.121212121,"from, this, into, humans"
19871,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.121212121,"a, we, the, to"
19872,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.121212121,"a, to, by, the"
19873,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.121212121,"was, to, the, animals"
19874,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.121212121,"covs, a, of, have, and, the, to, species"
19875,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.121212121,"the, and, bat, of"
19876,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.121212121,"a, zoonotic, the, and"
19877,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.121212121,"zoonotic, in, and, to"
19878,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.121212121,"sars-cov-2, genome, to, a"
19879,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.121212121,"sars-cov-2, the, with, cov"
19880,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.121212121,"virus, to, sars-cov-2, genome"
19881,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.121212121,"in, related, to, the"
19882,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.121212121,"the, sars-cov-2, that, in"
19883,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.121212121,"the, that, not, is"
19884,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.121212121,"that, is, to, the"
19885,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.121212121,"research, that, the, sars-cov-2"
19886,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.121212121,"the, is, related, to"
19887,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.121212121,"of, a, in, horseshoe"
19888,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.121212121,"of, that, sars-cov-2, a"
19889,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.121212121,"that, in, of, sars-cov-2"
19890,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.121212121,"similar, to, the, sars-cov-2"
19891,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.121212121,"the, to, is, strain"
19892,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.121212121,"that, sars-cov-2, the, to"
19893,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.121212121,"virus, the, market, from"
19894,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.121212121,"the, that, is, not"
19895,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.121212121,"the, a, zoonotic, host"
19896,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.121212121,"that, is, not, a"
19897,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","bats are also important reservoir species for a great 

range of coronaviruses",0.121212121,"bats, species, reservoir, of"
19898,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.121212121,"sars-cov-2, the, of, infection"
19899,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.121212121,"were, bats, in, the"
19900,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.121212121,"an, in, were, of"
19901,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.121212121,"sars-cov-2, from, to, and"
19902,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.121212121,"the, sequence, with, from"
19903,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.121212121,"pangolin-cov, in, the, sars-cov-2"
19904,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.121212121,"the, with, pangolin-cov, sars-cov-2"
19905,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.121212121,"in, the, was, a, that, to, and, variant"
19906,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.121212121,"to, as, the, host"
19907,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.121212121,"the, from, to, a"
19908,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.121212121,"the, as, from, a"
19909,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.121212121,"a, team, from, the"
19910,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.121212121,"the, host, zoonotic, a"
19911,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.121212121,"the, species, to, and"
19912,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.121212121,"sars-cov-2, and, in, animal"
19913,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.121212121,"from, that, in, this"
19914,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.121212121,"sars-cov-2, to, with, bat"
19915,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.121212121,"the, of, sars-cov-2, dogs"
19916,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.121212121,"in, the, of, market"
19917,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.121212121,"from, a, rhinolophus, to, in, the, that, it"
19918,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.121212121,"the, coronaviruses, sars-cov-2, including"
19919,"bats are also important reservoir species for a great 

range of coronaviruses","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.121212121,"bats, reservoir, species, of"
19920,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.121212121,"the, most, of, sars-cov-2"
19921,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.121212121,"the, coronaviruses, including, sars-cov-2"
19922,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.121212121,"to, the, and, virus"
19923,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.121212121,"the, and, of, to"
19924,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.121212121,"the, sars-cov-2, and, at, two, both, which, a"
19925,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.121212121,"of, virus, that, is, similar, to, the, for"
19926,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.121212121,"of, the, have, that"
19927,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","This suggests that the BANAL series may be able to directly infect  

humans.",0.121212121,"to, that, the, this"
19928,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.121212121,"a, the, of, at"
19929,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.121212121,"the, strain, is, to"
19930,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.121212121,"is, the, most, of"
19931,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.121212121,"bats, and, was, in"
19932,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.121212121,"the, covid-19, ratg-13, is"
19933,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.121212121,"in, to, virus, be"
19934,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.121212121,"ratg-13, is, the, covid-19"
19935,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.121212121,"several, that, with, the"
19936,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.121212121,"in, a, related, that, the, closely, to, market"
19937,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.121212121,"the, for, of, into, humans, from, intermediate, host"
19938,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.121212121,"and, the, virus, from, to, humans,, a, in"
19939,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.121212121,"that, was, and, in, were, at, a, december"
19940,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.121212121,"in, the, of, a, to, as, taken, samples, found, moreover,, were, and, that, sars, from, outbreak"
19941,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.121212121,"the, in, of, an, to, that, was, virus"
19942,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.121212121,"of, a, that, the, virus, to, and, sars"
19943,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.121212121,"in, the, of, as, sars, a, outbreak, found, that, samples, taken, from, were, to, moreover,, and"
19944,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.121212121,"evidence, the, and, of, to, huanan, between, market"
19945,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.121212121,"the, between, and, huanan, market, of, evidence, to"
19946,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","expended to make the simple point 

that COVID-19 had a natural origin.",0.121212121,"the, that, natural, a"
19947,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","expended to make the simple point 

that COVID-19 had a natural origin.",0.121212121,"that, the, a, to"
19948,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.121212121,"and, coronaviruses, related, to"
19949,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.121212121,"sars-cov-2, and, humans, animal"
19950,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.121212121,"animal, sars-cov-2, and, in"
19951,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.121212121,"shows, identity, in, with"
19952,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.121212121,"that, not, is, a"
19953,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.121212121,"the, sars-cov-2, spike, to, a, of, is, human"
19954,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.121212121,"is, that, of, sars-cov-2"
19955,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.121212121,"that, sars-cov-2, a, it"
19956,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.121212121,"of, the, have, been"
19957,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.121212121,"that, the, virus, not"
19958,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.121212121,"that, is, likely, to"
19959,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.121212121,"to, from, a, in, rhinolophus, the, it, that"
19960,"Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.121212121,"a, possible, sars-cov-2, progenitor"
19961,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.121212121,"the, virus, probably, in"
19962,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.121212121,"virus, that, an, to"
19963,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.121212121,"in, the, of, an, was, that, virus, to"
19964,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.121212121,"an, in, pangolins, of"
19965,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.121212121,"this, that, sars-cov-2, in"
19966,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.121212121,"the, rbd, and, in, that, coronaviruses, not, of"
19967,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.121212121,"of, the, showed, that"
19968,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.121212121,"the, in, that, this, novel, coronavirus, originated, a"
19969,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",The COVID-19 most likely developed from bat origin coronaviruses,0.121212121,"from, the, bat, origin"
19970,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.121212121,",, that, the, of"
19971,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.121212121,"and, in, to, that, the, of, bats, hosts"
19972,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.121212121,"and, to, covs, in"
19973,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.121212121,"to, in, zoonotic, and"
19974,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.121212121,"in, can, be, and"
19975,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.121212121,"were, to, in, humans"
19976,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.121212121,"the, in, wuhan,, china"
19977,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.121212121,"have, that, the, of"
19978,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.121212121,"the, of, and, it, virus, that, is, most"
19979,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.121212121,"the, of, is, for, virus, similar, to, that"
19980,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.121212121,"and, it, to, was, for, the, of, that"
19981,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.121212121,"a, of, the, coronavirus, viruses, that, bats, key"
19982,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.121212121,"that, have, of, and, pangolins, are, the, for"
19983,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.121212121,"the, isolated, from, is"
19984,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.121212121,"to, the, humans, from"
19985,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.121212121,"the, to, be, and"
19986,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.121212121,"and, the, is, direct"
19987,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.121212121,"be, the, between, and"
19988,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.121212121,"virus, to, be, in"
19989,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.121212121,"the, and, in, of"
19990,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.121212121,"the, market, and, of"
19991,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.121212121,"in, a, the, market"
19992,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.121212121,"and, patients, the, of"
19993,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.121212121,"the, in, and, of"
19994,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.121212121,"the, market, of, in"
19995,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.121212121,"of, was, the, in"
19996,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.121212121,"in, the, and, a"
19997,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.121212121,"the, a, of, and"
19998,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.121212121,"in, bats, were, the"
19999,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.121212121,"in, an, of, were"
20000,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.121212121,"in, pangolins, of, an"
20001,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.121212121,"is, likely, to, from"
20002,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.121212121,"have, the, of, covs, to, a, and, species"
20003,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.121212121,"the, from, sars-cov-2, to, a, and, pangolin, coronavirus"
20004,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.121212121,"and, the, bats, in"
20005,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.121212121,"of, and, other, humans"
20006,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.121212121,"zoonotic, for, the, and"
20007,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.121212121,"to, suggest, that, the, of, have, are, origin"
20008,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.121212121,"it, that, sars-cov-2, a"
20009,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.121212121,"the, for, of, sars-cov-2, into, jumps, from, intermediate"
20010,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.121212121,"its, and, the, was, from, to, a, in"
20011,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.121212121,"of, that, it, to, the, and, for, was"
20012,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.121212121,"the, was, not, of"
20013,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.121212121,"an, animal, the, transmission"
20014,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.121212121,"the, an, unknown, animal"
20015,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.121212121,"bat, sars-cov-2, genome, the"
20016,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.121212121,"for, the, as, natural, of, is, it, with"
20017,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.121212121,"consistent, that, the, of, as, for, are, sars-cov-2"
20018,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.121212121,"viral, of, the, natural"
20019,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.121212121,"the, of, and, human"
20020,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.121212121,"identity, and, 96%, to"
20021,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.121212121,"from, to, sars-cov-2, and"
20022,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.121212121,"to, that, sars-cov-2, was"
20023,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.121212121,"and, that, sars-cov-2, viruses"
20024,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.121212121,"that, sars-cov-2, and, ratg13"
20025,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.121212121,"are, to, based, on, in, and, that, bats"
20026,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.121212121,"of, to, be, the"
20027,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.121212121,"sars-cov-2, to, coronaviruses, the"
20028,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.121212121,"the, was, in, animals"
20029,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.121212121,"the, shown, to, sars-cov-2"
20030,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.121212121,"the, that, bats, for"
20031,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.121212121,"the, that, research, sars-cov-2"
20032,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.121212121,"that, bats, the, sars-cov-2"
20033,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.121212121,"coronavirus, from, a, pangolin, and, sars-cov-2, to, the"
20034,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.121212121,"and, all, sars-cov-2, bat, pangolin, cluster, that, the"
20035,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.121212121,"the, believed, to, as"
20036,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.121212121,"the, is, to, bats"
20037,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.121212121,"for, that, the, sars-cov-2"
20038,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.121212121,"is, the, for, sars-cov-2"
20039,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.121212121,"the, of, sars, a, that, virus, to, and"
20040,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.121212121,"a, origin, of, the, by, sars-cov-2, at, in"
20041,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.121212121,"the, sars-cov-2, genome, bat"
20042,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.121212121,"the, sars-cov-2, and, have, to, a, of, recombination"
20043,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.121212121,"and, a, to, the, of, with, pangolin, intermediate"
20044,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.121212121,"that, are, the, of, and, have, pangolins, for"
20045,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.121212121,"the, that, a, novel, in, this, coronavirus, originated"
20046,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.121212121,"the, have, been, to"
20047,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.121212121,"to, been, the, sars-cov-2"
20048,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.121212121,"sars-cov-2, viruses, that, and"
20049,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.121212121,"sars-cov-2, to, bat, pangolin"
20050,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.121212121,"to, sars-cov-2, is, pangolin"
20051,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.121212121,"the, that, part, of"
20052,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.121212121,"in, bats, are, to, that, based, on, and"
20053,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.121212121,"of, the, from, this, that, sars-cov-2, and, viruses"
20054,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.121212121,"the, that, all, sars-cov-2, cluster, bat, and, pangolin"
20055,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.121212121,"bat, the, of, this"
20056,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.121212121,"the, bat, cov, pangolin"
20057,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.121212121,"the, bats, are, in"
20058,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.121212121,"sars-cov-2, that, in, this"
20059,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.121212121,"the, are, in, sars-cov-2"
20060,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.121212121,"the, ratg13, bat, sars-cov-2"
20061,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.121212121,"sars-cov-2, that, ratg13, and"
20062,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.121212121,"the, has, with, bat"
20063,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.121212121,"sars-cov-2, with, the, cov"
20064,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.121212121,"the, that, of, origin"
20065,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.121212121,"the, of, more, than"
20066,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.121212121,"the, bat, pangolin, cov"
20067,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.121212121,"in, that, sars-cov-2, this"
20068,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.121212121,"of, the, are, that, suggest, have, to, origin"
20069,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.121212121,"the, that, are, consistent, of, sars-cov-2, as, for"
20070,The COVID-19 most likely developed from bat origin coronaviruses,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.121212121,"the, from, bat, origin"
20071,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.121212121,"sars-cov-2, a, genome, to"
20072,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.121212121,"sars-cov-2, with, and, that"
20073,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.121212121,"with, and, sars-cov-2, to"
20074,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.121212121,"that, to, sars-cov-2, and"
20075,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.121212121,"sars-cov-2, with, that, and"
20076,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.121212121,"sars-cov-2, and, similarity, to"
20077,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.121212121,"is, the, sars-cov-2, to"
20078,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.121212121,"sars-cov-2, with, and, is"
20079,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.121212121,"and, the, of, is"
20080,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.121212121,"the, from, for, spillover"
20081,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.121212121,"and, sars-cov-2, in, of"
20082,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.121212121,"the, pangolin-cov, sars-cov-2, in"
20083,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.121212121,"the, of, and, that"
20084,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.121212121,"that, the, for, sars-cov-2"
20085,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.121212121,"the, in, bats,, and"
20086,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.121212121,"a, from, the, malayan"
20087,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.121212121,"a, the, and, cov"
20088,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.121212121,"the, pangolin-cov, sars-cov-2, with"
20089,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.121212121,"are, to, the, sars-cov-2"
20090,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.121212121,"the, in, and, sars-cov-2"
20091,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.121212121,"the, in, are, sars-cov-2"
20092,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.121212121,"in, and, can, be"
20093,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.121212121,"the, that, in, for"
20094,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.121212121,"in, that, the, bat"
20095,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.121212121,"studies, that, sars-cov-2, such"
20096,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.121212121,"is, that, to, sars-cov-2"
20097,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.121212121,"to, is, likely, that"
20098,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.121212121,"to, from, is, likely"
20099,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.121212121,"that, sars-cov-2, bat-sl-cov-2, to"
20100,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.121212121,"the, of, most, is"
20101,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.121212121,"probable, of, sars-cov-2, the"
20102,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.121212121,"and, bat, host, of"
20103,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.121212121,"of, the, and, bat"
20104,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.121212121,"intermediate, host, sars-cov-2, the"
20105,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.121212121,"an, unknown, animal, the"
20106,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.121212121,"sars-cov-2, and, a, virus"
20107,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.121212121,"the, be, sars-cov-2, and"
20108,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.121212121,"a, the, sars-cov-2, and"
20109,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.121212121,"the, cov, and, a"
20110,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.121212121,"coronaviruses, in, a, of"
20111,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.121212121,"a, study, in, of"
20112,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.121212121,"the, a, zoonotic, and"
20113,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.121212121,"for, and, the, zoonotic"
20114,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.121212121,"and, that, of, in, many, which, such, as"
20115,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.121212121,"that, sars-cov-2, is, related, to, bats, be, the"
20116,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.121212121,"that, the, in, bats, and, to, hosts, of"
20117,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.121212121,"the, rbd, and, in, coronaviruses, not, that, of"
20118,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.121212121,"the, more, of, than"
20119,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.121212121,"the, of, coronaviruses, bat"
20120,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.121212121,"sars-cov-2, receptor-binding, domain, to"
20121,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.121212121,"sars-cov-2, similarity, to, and"
20122,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.121212121,"the, that, sars-cov-2, a"
20123,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.120879121,"a, of, the, has, that, or, scientific, have, to, origin, virus"
20124,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.120879121,"the, of, to, such, as, and, in, et, al., other, also"
20125,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.120879121,"in, the, of, sars, a, found, that, virus, to, closely, related"
20126,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.120879121,"the, of, closely, related, in, found, a, virus, to, sars, that"
20127,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.120879121,"other, such, as, et, al., also, the, of, and, in, to"
20128,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.120879121,"origin, of, has, to, a, virus, have, or, scientific, that, the"
20129,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.120805369,"the, of, a, sars-related, in, species, horseshoe, to, that, sars, bats, as, and, or, were, for, coronaviruses, viral"
20130,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.120805369,"to, the, sars, bats, were, as, viral, for, and, a, in, of, species, horseshoe, that, sars-related, coronaviruses, or"
20131,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.120689655,"bats, are, the, of, and, be, to"
20132,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.120689655,"with, of, bats, were, for, bats,, and"
20133,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.120689655,"sars-cov-2, including, the, coronaviruses, that, any, of"
20134,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.120689655,"the, genetic, sars-cov-2, sequence, virus, is, that"
20135,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.120689655,"from, a, is, its, in, the, that"
20136,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.120689655,"to, sars-cov-2, of, in, the, and, with"
20137,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.120689655,"the, of, to, that, sars-cov-2, changes, and"
20138,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.120689655,"bats, of, and, are, to, be, the"
20139,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.120689655,"and, appear, to, an, in, the, of"
20140,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.120689655,"the, and, that, a, sequence, in, to"
20141,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.120689655,"the, that, in, a, human, and, to"
20142,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.120689655,"coronavirus, a, and, sars-cov-2, to, be, the"
20143,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.120689655,"that, the, in, to, with, a, and"
20144,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.120689655,"a, that, humans, with, to, the, for"
20145,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.120689655,"be, sars-cov-2, to, humans, pangolins, the, in"
20146,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.120689655,"has, been, found, in, the, to, through"
20147,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.120689655,"the, that, was, spillover, of, sars-cov-2, into"
20148,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.120689655,"into, before, was, the, of, that, sars-cov-2"
20149,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.120689655,"the, of, and, that, sars-cov-2, animal, humans"
20150,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.120689655,"the, at, huanan, market, and, of, with"
20151,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.120689655,"in, the, of, and, with, at, huanan"
20152,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.120689655,"in, the, of, coronavirus, from, most, hosts"
20153,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.120689655,"a, report, and, to, of, in, the"
20154,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.120689655,"that, the, of, cases, in, to, a"
20155,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.120689655,"if, in, it, is, that, and, sars-cov-2"
20156,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.120689655,"is, sars-cov-2, and, to, viruses, that, in"
20157,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.120689655,"from, a, virus, that, is, in, this"
20158,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.120689655,"the, to, sars-cov-2, was, an, of, a"
20159,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.120689655,"the, to, and, that, was, a, but"
20160,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.120689655,"a, virus, bat, to, and, as, on"
20161,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.120689655,"the, and, has, a, to, that, bat"
20162,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.120689655,"in, the, a, that, to, and, with"
20163,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.120689655,"cases, in, the, of, that, a, to"
20164,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.120689655,"the, of, cases, in, they, this, to"
20165,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.120689655,"of, the, been, that, or, to, virus"
20166,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.120689655,"this, of, cases, to, the, in, they"
20167,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.120689655,"bats, as, the, was, to, be, and"
20168,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.120689655,"that, the, virus, and, to, from, a"
20169,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.120689655,"the, genome, of, coronavirus, to, bat, for"
20170,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.120689655,"the, from, a, and, to, of, with"
20171,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.120689655,"the, of, from, to, humans, infected, and"
20172,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.120689655,"the, by, of, and, that, originated, a"
20173,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.120689655,"the, of, sars-cov-2, to, is, on, that"
20174,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.120689655,"bats, are, and, a, to, in, humans,"
20175,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.120689655,"the, virus, a, to, that, from, and"
20176,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.120689655,"that, have, a, virus, to, and, the"
20177,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.120689655,"and, virus, the, covid-19, was, in, of"
20178,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.120689655,"is, a, natural, with, on, the, for"
20179,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.120689655,"a, of, be, with, novel, coronavirus, that"
20180,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.120689655,"the, for, genome, of, to, coronavirus, bat"
20181,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.120689655,"of, the, is, bat, animal, models, for"
20182,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.120689655,"to, be, bats, and, was, the, as"
20183,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.120689655,"sequence, with, bat, cov, that, and, sars-cov-2"
20184,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.120689655,"the, of, that, sars-cov-2, with, bat, cov"
20185,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.120689655,"is, that, sars-cov-2, the, virus, genetic, sequence"
20186,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.120689655,"is, that, sars-cov-2, the, of, virus, genome"
20187,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.120689655,"a, to, virus, that, transmitted, is, from"
20188,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.120689655,"of, sars-cov-2, to, is, likely, that, another"
20189,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.120689655,"another, of, that, is, animal, species, intermediate"
20190,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.120689655,"that, by, of, to, and, intermediate, sars-cov-2"
20191,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.120689655,"in, of, the, covid-19, virus, and, was"
20192,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.120689655,"the, bats, to, as, of, intermediate, and"
20193,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.120689655,"the, and, has, to, that, bat, of"
20194,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.120689655,"the, a, that, from, to, humans, and"
20195,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.120689655,"the, of, sars-cov, that, sequences, are, to"
20196,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.120689655,"in, a, virus, that, this, is, from"
20197,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.120689655,"from, this, that, sars-cov-2, may, in, a"
20198,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.120689655,"coronavirus, in, most, the, of, from, hosts"
20199,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.120689655,"on, from, in, the, of, based, these"
20200,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.120689655,"sars-cov-2, a, of, the, and, that, with"
20201,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.120689655,"a, the, to, that, in, sequence, and"
20202,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.120689655,"the, sequences, are, to, that, of, sars-cov"
20203,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.120689655,"that, the, of, viruses, similar, to, coronaviruses"
20204,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.120689655,"the, sequence, of, to, sars-cov, and, in"
20205,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.120689655,"however,, the, of, low, to, sars-cov-2,, that"
20206,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.120689655,"in, from, species, bats, to, sars-cov-2, and"
20207,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.120689655,"that, between, sars-cov-2, and, bat, is, which"
20208,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.120689655,"is, bat, coronavirus, to, be, sequence, in"
20209,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.120689655,"the, sequences, of, two, and, which, sars-cov-2"
20210,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.120689655,"with, and, of, at, the, huanan, in"
20211,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.120689655,"a, was, the, of, sars-cov-2, to, an"
20212,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.120689655,"the, in, rbd, found, similar, to, ratg13"
20213,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.120689655,"of, sars-cov-2, ratg13, in, which, the, to"
20214,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.120689655,"a, and, linked, to, of, which, the"
20215,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.120689655,"of, bats,, and, bats, for, were, with"
20216,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.120689655,"sars-cov-, a, of, with, and, the, for"
20217,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.120689655,"be, possible, a, bat, to, of, as"
20218,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.120689655,"the, of, coronaviruses, that, viruses, similar, to"
20219,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.120689655,"the, of, to, changes, that, and, sars-cov-2"
20220,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.120689655,"to, of, from, a, with, sars-cov-2, years"
20221,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.120689655,"the, of, to, that, sars-cov-2, from, bats"
20222,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.120689655,"the, sequences, of, sars-cov-2, and, two, which"
20223,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.120689655,"sars-cov-2, of, the, and, sars-, cov-2, analysis"
20224,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.120689655,"et, al., (2020), to, and, the, sars-cov-2"
20225,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.120689655,"sars-cov-2, and, from, species, to, in, bats"
20226,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.120689655,"several, in, bats, to, of, sars-cov-2, and"
20227,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.120689655,"found, in, the, to, ratg13, rbd, similar"
20228,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.120689655,"mutations,, and, can, the, of, that, natural"
20229,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.120689655,"the, of, rbd, to, that, sars-cov-2, can"
20230,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.120689655,"the, sars-cov-2, to, humans, pangolins, in, be"
20231,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.120689655,"between, intermediate, and, pangolins, may, the, in"
20232,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.120689655,"the, has, been, to, through, in, found"
20233,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.120689655,"with, the, and, sars-cov-2, to, in, of"
20234,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.120689655,"in, it, that, the, recombination, and, of"
20235,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.120689655,"the, sars-cov-2, of, genome, virus, is, that"
20236,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.120689655,"of, the, and, mers, as, viruses, sars"
20237,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.120689655,"and, to, the, bats, of, as, intermediate"
20238,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.120689655,"in, china, that, the, closely, related, to"
20239,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.120689655,"and, in, were, to, closely, related, the"
20240,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.120689655,"the, of, appear, and, in, to, an"
20241,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.120689655,"of, the, bat, a, species,, species, possible"
20242,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.120689655,"by, a, of, similar, and, are, the"
20243,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.120689655,"covid-19, a, in, the, that, but, caves"
20244,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.120689655,"of, from, to, a, with, sars-cov-2, years"
20245,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","This suggests that the BANAL series may be able to directly infect  

humans.",0.120689655,"to, humans., this, the, that, may, infect"
20246,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.120689655,"the, as, of, most, to, by, bat"
20247,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.120689655,"that, if, it, sars-cov-2, and, is, in"
20248,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.120689655,"the, of, with, and, huanan, market, at"
20249,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.120689655,"the, a, of, to, with, from, and"
20250,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.120689655,"by, a, of, with, to, and, the"
20251,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.120689655,"a, of, in, guangdong, that, animal, sars, with, had, the, suggesting, or, to, virus"
20252,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.120689655,"that, sars, had, a, the, virus, animal, or, with, of, in, guangdong, suggesting, to"
20253,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.120689655,"the, report, in, a, to, of, and"
20254,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.120689655,"linked, the, of, to, a, and, which"
20255,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.120689655,"at, is, within, the, with, that, are"
20256,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.120689655,"that, sars-cov-2, was, the, of, spillover, into"
20257,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.120689655,"evidence, between, and, that, in, the, of"
20258,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.120689655,"the, a, that, to, humans, with, for"
20259,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.120689655,"a, for, the, on, natural, is, with"
20260,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.120689655,"to, sars-cov-2, the, that, for, is, natural"
20261,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.120689655,"the, that, with, natural, sars-cov-2, is, for"
20262,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.120689655,"that, rhinolophus, bats, and, in, china, pangolins"
20263,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.120689655,"on, the, of, that, sars-cov-2, is, to"
20264,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.120689655,"is, likely, that, of, sars-cov-2, to, another"
20265,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.120689655,"is, sars-cov-2, the, of, binding, protein, on"
20266,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.120689655,"is, that, from, a, the, its, in"
20267,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.120689655,"a, in, which, is, the, to, human"
20268,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.120689655,"sars-cov-2, is, natural, that, to, the, for"
20269,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.120689655,"mutations,, and, the, of, can, that, natural"
20270,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.120689655,"the, of, rbd, to, can, that, sars-cov-2"
20271,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.120689655,"sars-cov-2, the, of, any, that, coronaviruses, including"
20272,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.120689655,"that, a, was, the, and, but, to"
20273,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.120689655,"a, the, to, that, in, human, and"
20274,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.120689655,"the, of, sars-cov, and, sequence, in, to"
20275,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.120689655,"the, of, is, bat, animal, models, for"
20276,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.120689655,"is, that, of, intermediate, another, animal, species"
20277,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.120689655,"of, bat, species,, a, possible, species, the"
20278,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.120689655,"that, bats, the, of, and, in, 2019"
20279,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.120689655,"the, of, that, to, humans, hosts, and"
20280,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.120689655,"of, a, that, the, to, genus, and"
20281,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.120689655,"of, the, in, and, that, a, viruses"
20282,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.120689655,"that, similar, to, and, a, the, of"
20283,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.120689655,"that, in, rhinolophus, bats, and, pangolins, china"
20284,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.120689655,"that, the, in, bats, and, of, 2019"
20285,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.120689655,"and, from, to, be, the, is, bats"
20286,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.120689655,"on, virus, as, a, bat, and, to"
20287,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.120689655,"as, to, of, be, possible, a, bat"
20288,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.120689655,"the, binding, of, sars-cov-2, protein, is, on"
20289,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.120689655,"of, virus, with, similar, pangolins, the, sars-cov-2"
20290,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.120689655,"and, may, intermediate, pangolins, the, between, in"
20291,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.120689655,"covs, a, also, the, to, from, animals"
20292,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.120689655,"a, from, the, is, related, to, covs"
20293,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.120689655,"the, to, covs, a, from, animals, also"
20294,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.120689655,"infected, to, humans, from, and, the, of"
20295,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.120689655,"that, the, from, a, to, humans, and"
20296,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.120689655,"the, of, most, to, as, by, bat"
20297,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.120689655,"that, the, and, to, humans, hosts, of"
20298,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.120689655,"cov, sequence, with, bat, that, sars-cov-2, and"
20299,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.120689655,"sars-cov-2, to, be, a, coronavirus, and, the"
20300,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.120689655,"of, to, the, that, been, virus, or"
20301,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.120689655,"that, sars-cov-2, was, the, of, before, into"
20302,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.120689655,"sars-cov-2, may, from, a, that, in, this"
20303,"This suggests that the BANAL series may be able to directly infect  

humans.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.120689655,"this, that, the, may, to, infect, humans."
20304,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.120689655,"sars-cov-2, was, made, from, that, to, and"
20305,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.120689655,"sars-cov-2, is, natural, that, with, the, for"
20306,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.120689655,"natural, of, and, a, diversity, as, human"
20307,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.120689655,"from, and, made, to, was, that, sars-cov-2"
20308,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.120689655,"in, of, bats, to, sars-cov-2, and, several"
20309,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.120689655,"these, sars-cov-2, with, bat, ratg13, demonstrates, than"
20310,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.120689655,"the, to, that, closely, related, in, china"
20311,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.120689655,"the, related, to, covs, a, from, is"
20312,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.120689655,"the, of, to, that, was, from, bats"
20313,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.120689655,"to, the, of, genus, and, that, a"
20314,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.120689655,"in, the, of, which, sars-cov-2, to, ratg13"
20315,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.120689655,"a, is, to, in, the, which, human"
20316,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.120689655,"have, that, the, virus, and, to, a"
20317,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.120689655,"and, that, of, sars-cov-2, to, intermediate, by"
20318,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.120689655,"with, the, of, a, for, sars-cov-, and"
20319,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.120689655,"et, al., (2020), to, the, sars-cov-2, and"
20320,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.120689655,"of, and, similar, are, by, a, the"
20321,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.120689655,"the, by, a, and, to, of, with"
20322,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.120689655,"virus, pangolins, similar, with, sars-cov-2, the, of"
20323,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.120689655,"a, of, that, originated, by, the, and"
20324,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.120689655,"viruses, the, in, of, and, that, a"
20325,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.120689655,"as, the, viruses, of, sars, and, mers"
20326,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.120689655,"the, is, that, are, with, within, at"
20327,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.120689655,"that, sars-cov-2, to, and, is, viruses, in"
20328,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.120689655,"these, bat, demonstrates, with, sars-cov-2, than, ratg13"
20329,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.120689655,"sars-cov-2, is, between, and, bat, which, that"
20330,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.120689655,"based, on, in, the, of, from, these"
20331,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.120689655,"similar, to, the, of, and, that, a"
20332,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.120689655,"cov, with, bat, that, the, of, sars-cov-2"
20333,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.120689655,"evidence, in, the, and, that, of, between"
20334,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.120689655,"recombination, of, in, the, and, it, that"
20335,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.120689655,"the, of, that, low, however,, to, sars-cov-2,"
20336,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.120689655,"that, of, from, bats, to, sars-cov-2, the"
20337,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.120689655,"from, was, that, the, to, of, bats"
20338,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.120689655,"that, the, covid-19, in, caves, but, a"
20339,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.120689655,"a, of, be, novel, coronavirus, with, that"
20340,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.120689655,"are, and, bats, to, humans,, a, in"
20341,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.120689655,"of, natural, a, human, as, and, diversity"
20342,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.120689655,"the, and, closely, related, to, were, in"
20343,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.120689655,"is, sequence, bat, be, to, coronavirus, in"
20344,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.120689655,"the, a, that, has, bat, and, to"
20345,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.120689655,"analysis, of, the, sars-, cov-2, and, sars-cov-2"
20346,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.120567376,"in, of, wiv, to, the, different, coronavirus, most, and, sars, at, viruses, more, closely, related, than, any"
20347,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.120567376,"the, viruses, wiv, to, more, closely, related, most, sars, coronavirus, in, different, than, of, and, at, any"
20348,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.120481928,"bats, the, of, are, known, as, and, been, other, mammals"
20349,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.120481928,"at, to, animal, in, the, live, were, several, and, species"
20350,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.120481928,"the, in, of, similar, to, that, can, this, also, virus"
20351,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.120481928,"other, that, are, also, similar, to, and, a, the, of"
20352,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.120481928,"several, animal, species, to, were, live, and, in, at, the"
20353,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.120481928,"the, of, also, to, similar, that, this, in, can, virus"
20354,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.120481928,"bats, are, the, mammals, been, known, as, of, and, other"
20355,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.120481928,"and, the, of, also, to, similar, are, a, other, that"
20356,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.12037037,"for, the, of, and, that, virus, into, a, in, this, with, as, to"
20357,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.12037037,"its, into, as, and, to, this, for, the, of, that, in, a, infect"
20358,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.12037037,"and, the, of, to, as, a, with, that, into, this, in, for, virus"
20359,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.12037037,"and, the, of, to, as, a, infect, that, into, this, in, for, its"
20360,"An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.12,"reservoir, of, coronaviruses"
20361,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.12,"bats, reservoir, of"
20362,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.12,"reservoir, in, bats"
20363,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.12,"a, of, data, that, the, and"
20364,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.12,"a, of, in, and, the, new"
20365,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.12,"that, bats, the, a, of, and"
20366,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.12,"a, sars-cov-2, and, to, which, sars-cov"
20367,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.12,"in, related, pangolin, and, which, to"
20368,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.12,"are, in, of"
20369,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.12,"of, are, animal"
20370,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.12,"coronaviruses, of, reservoir"
20371,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.12,"bats, the, be, species, of, are, known, to, and"
20372,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.12,"to, the, of, bats, and, are"
20373,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.12,"were, more, that, virus, animals, and"
20374,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.12,"of, virus, revealed, that, and, for"
20375,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.12,"to, in, and"
20376,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.12,"and, coro-, navirus, bats, from, by"
20377,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.12,"sars-, and, are, similar, to, the"
20378,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.12,"is, sars-cov-2, in"
20379,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.12,"the, of, palm, virus, from, to, human, and, civet"
20380,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.12,"the, from, to, which, humans,, and"
20381,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.12,"of, virus, to, the, bat, and"
20382,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.12,"to, the, sars-cov-2, as, a, of"
20383,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.12,"is, with, a, of, the, in"
20384,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.12,"that, the, of, sars-cov-2, to, it"
20385,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.12,"that, the, of, to, sars-cov-2, coronaviruses"
20386,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.12,"the, coronaviruses, to, that, sars-cov-2, including"
20387,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.12,"closest, to, of, have, from, sars-cov-2"
20388,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.12,"the, that, sars-cov-2, closest, of, to"
20389,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.12,"it, is, coronavirus"
20390,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.12,"have, that, the, of, binds, affinity, to, human, ace2"
20391,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.12,"sars-cov-2, be, a, between, the, and"
20392,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.12,"sars-cov-2, genetic, is, a, virus, that"
20393,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.12,"sars-cov-2, was, also, the, its, in"
20394,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.12,"is, that, sars-cov-2, a, virus, genetic"
20395,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.12,"the, and, of, to, that, bat"
20396,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.12,"the, genome, to, with, that, bat"
20397,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.12,"that, have, with, to, the, sars-cov-2"
20398,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.12,"sars-cov-2, the, of, that, to, it"
20399,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.12,"on, as, natural, of, bat, and"
20400,"expended to make the simple point 

that COVID-19 had a natural origin.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.12,"the, a, natural"
20401,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.12,"96.2%, to, genome, sequence, was, bat"
20402,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.12,"pangolin, many, in, and, that, of"
20403,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.12,"analysis, that, in, and, intermediate, of"
20404,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.12,"sars-cov-2, to, of"
20405,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.12,"of, to, sars-cov-2"
20406,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",Originating from reservoir of bat,0.12,"of, bat, reservoir"
20407,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.12,"changes, and, that, have, the, of"
20408,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.12,"the, between, and, of, origin, to"
20409,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.12,"been, the, of, as, and, long"
20410,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.12,"other, and, most, been, the, of"
20411,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.12,"in, the, variants, and, are, to, use, that, ability"
20412,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.12,"closest, to, the, in, and, that"
20413,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.12,"the, long, been, as, of, and"
20414,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.12,"in, wuhan, china, the, of, and"
20415,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.12,"the, on, wet, that, infected, were"
20416,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.12,"to, this, that, the, origin, of"
20417,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.12,"sars-cov-2, a, of, animal, and, the"
20418,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.12,"and, be, sars-cov-2, transmission, to, the"
20419,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.12,"the, mers-cov, and"
20420,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.12,"the, be, of"
20421,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.12,"bats, and, hosts"
20422,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.12,"bats, natural, hosts, of, and, cov,"
20423,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.12,"the, of, covid-19, with, genomic, at"
20424,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.12,"was, the, to, which, is, previously"
20425,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",zoonotic origins of SARS-CoV-2 by natural evolution,0.12,"sars-cov-2, of, natural"
20426,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",zoonotic origins of SARS-CoV-2 by natural evolution,0.12,"sars-cov-2, zoonotic, of"
20427,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.12,"to, in, bats,"
20428,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.12,"was, in, and"
20429,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.12,"the, was, to"
20430,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.12,"bat, that, the, of, sars-cov-2, analysis"
20431,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.12,"the, is, that, of, with, and"
20432,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.12,"from, humans, to, are, coronaviruses, the"
20433,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.12,"the, that, coronavirus, highly, to, coronaviruses"
20434,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.12,"the, animals, are, to, in, a, for, with, time, was, that, and"
20435,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.12,"the, sars-cov-2, and, to, be, of"
20436,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.12,"and, to, the, bats, be, of"
20437,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","with the first case being linked to  

a seafood market",0.12,"to, a, the"
20438,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","with the first case being linked to  

a seafood market",0.12,"with, to, the"
20439,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.12,"that, been, by, a, virus, the"
20440,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.12,"with, that, to, sars-, cov-2, at"
20441,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.12,"a, bat, found, in, similarity, sars-cov-2"
20442,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.12,"as, a, of, the, to, sars-cov-2"
20443,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.12,"the, of, to, that, sars-cov-2, a"
20444,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.12,"are, the, genome, and, that, could"
20445,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.12,"the, of, changes, that, have, and"
20446,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.12,"have, the, and, of, that, bat"
20447,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.12,"a, sars-cov-2, the, of, from, bat"
20448,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.12,"and, a, of, sars-cov-2, in, their, which, the, viruses"
20449,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.12,"that, the, market, animals, sold, of"
20450,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.12,"the, of, to, that, sars-cov-2, and"
20451,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.12,"the, that, in, and, jumped, humans"
20452,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.12,"in, the, more, to, that, a"
20453,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.12,"a, of, the, in, is, with"
20454,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.12,"the, with, in, market, a, of"
20455,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.12,"in, a, with, and, at, the"
20456,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.12,"and, a, of, in, is, the"
20457,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.12,"the, most, been, of, and, other"
20458,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.12,"a, the, to, laboratory, and, in"
20459,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.12,"samples, that, from, the, animals, also"
20460,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.12,"in, the, of, more, than, it, is, not, to, that, sars-cov-2, and"
20461,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.12,"it, was, in, by, closely, related, and, are, to, sars-cov-2, at, the"
20462,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.12,"on, the, infected, that, were, wet"
20463,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.12,"cases, with, the, market,, that, there, were, sars-cov-2, be, infected, by, at"
20464,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.12,"in, a, of, being, for, were, found, to, that"
20465,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.12,"we, the, and, in, not, that, of, is, plausible"
20466,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.12,"evidence, that, sars-cov-2, a, and, is"
20467,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.12,"as, of, from, bats,, such, and"
20468,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.12,"a, the, coronavirus, with, bat, that"
20469,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.12,"a, january, on, and, to, the"
20470,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.12,"samples, from, also, the, that, animals"
20471,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.12,"that, have, a, of, to, and"
20472,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.12,"was, a, and, to, the, genome"
20473,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.12,"as, the, was, to, be, of"
20474,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.12,"with, the, of"
20475,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.12,"that, the, and, to, which, is"
20476,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.12,"the, of, which, that, to, virus"
20477,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.12,"the, be, to, that, and, sars-cov-2"
20478,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.12,"from, a, is, to, the, that"
20479,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.12,"that, to, with, genome, bat, the"
20480,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.12,"and, the, virus, from, to, a"
20481,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.12,"about, the, of, covid-19, to, that"
20482,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.12,"which, has, the, with, identity, genome"
20483,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","Bats have been reported as being the rich source of 

coronaviruses",0.12,"the, have, been"
20484,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.12,"has, been, to"
20485,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.12,"a, to, the, coronavirus, with, pangolin"
20486,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.12,"the, of, and, sars-cov-2, to, humans"
20487,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.12,"the, and, to, humans, from, infected"
20488,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.12,"the, from, and, to, of, with"
20489,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.12,"a, of, and, data, that, the"
20490,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.12,"that, sars-cov-2, a, the, of, virus"
20491,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.12,"by, a, and, to, sars-cov-2, the"
20492,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.12,"a, to, recombination, sars-cov-2, the, and"
20493,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.12,"and, a, of, sars-cov-2, the, to"
20494,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.12,"is, to, human"
20495,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.12,"is, between, and, bat, be, to"
20496,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.12,"human, the, of"
20497,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.12,"and, the, of, to, be, is"
20498,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.12,"the, to, and"
20499,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.12,"analysis, that, sars-cov-2, is, to, the"
20500,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.12,"the, was, and, on, that, of"
20501,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.12,"an, and, humans, was, by, the"
20502,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.12,"the, virus, a, to, from, and"
20503,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.12,"a, virus, to, and, are, the"
20504,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.12,"infected, to, humans, from, and, the"
20505,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.12,"the, that, through, and, from, a"
20506,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.12,"a, at, the, in, wuhan,, china"
20507,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.12,"that, the, at, virus, and, to"
20508,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.12,"the, covid-19, of, about, to, that"
20509,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.12,"the, covid-19, to, which, and, animals"
20510,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.12,"in, bats,, to"
20511,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.12,"has, been, that"
20512,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.12,"that, has, to"
20513,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.12,"more, animals, and, that, virus, were"
20514,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.12,"the, and, that, jumped, humans, in"
20515,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.12,"the, and, mers-cov"
20516,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.12,"the, animal, and"
20517,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.12,"to, sars-cov, mers-cov"
20518,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.12,"and, the, to, similar, that, in, virus, is, its"
20519,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.12,"similar, to, the, in, and, that"
20520,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.12,"that, to, and"
20521,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.12,"of, the, in, december, 2019, and"
20522,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.12,"the, genus, and"
20523,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.12,"also, the, bat"
20524,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.12,"that, the, of, and, is, to"
20525,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.12,"that, and, may, be, to, the"
20526,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.12,"the, sars-, to, is, reservoir, for"
20527,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.12,"on, and, bat, as, natural, of"
20528,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.12,"of, reservoir, bats"
20529,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.12,"the, reservoir, be"
20530,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.12,"the, analysis, that, sars-cov-2, is, to"
20531,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.12,"to, is, possible, that, related, bat"
20532,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.12,"the, that, first, seafood, market, in"
20533,The FCS of SARS-CoV-2 was not bioengineered—full stop.,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.12,"the, was, not"
20534,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.12,"the, market, sold, animals, that, of"
20535,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.12,"with, a, of, the, market, in"
20536,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.12,"suggested, that, a, the, was, or, with, of, in, patients, have, live"
20537,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.12,"the, results, that, be, hosts, for"
20538,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.12,"the, a, coronavirus, that, with, bat"
20539,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.12,"the, of, be, possible, a, bat"
20540,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.12,"a, that, genomic, with, the, bat"
20541,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.12,"however,, the, of, that, not, bats"
20542,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.12,"the, of, to"
20543,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.12,"sars-cov, and, sars-cov-2, to, a, which"
20544,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.12,"is, the, to, which, was, previously"
20545,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.12,"the, which, is, to, that, and"
20546,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.12,"by, the, a, to, that, and, also, used, ace2, it, mechanism, for"
20547,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.12,"the, was, to, be, of, as"
20548,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.12,"be, of, the, and, with, to, infection, analysis, rbd"
20549,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.12,"the, analysis, that, sars-cov-2, of, bat"
20550,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.12,"and, that, have, the, bat, of"
20551,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.12,"the, is, of, sars-cov-2, to, virus"
20552,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.12,"sars-cov-2, is, to, have, the, bat"
20553,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.12,"the, of, that, sars-cov-2, is, virus"
20554,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.12,"that, sars-cov-2, several"
20555,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.12,"have, to, sars-cov-2"
20556,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.12,"in, the, bats"
20557,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",Many of these CoVs can infect several animal species as well,0.12,"animal, of, as"
20558,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.12,"that, an, animal"
20559,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.12,"the, coronaviruses, are, from, to, humans"
20560,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.12,"that, in, bat"
20561,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.12,"they, in, their"
20562,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.12,"that, have, in"
20563,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.12,"and, the, genus"
20564,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.12,"in, the, rhinolophus"
20565,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.12,"to, the, in, and, or, could"
20566,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.12,"that, a, sars-cov-2, and, evidence, is"
20567,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.12,"sars-cov-2, a, animal, and, that, or"
20568,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.12,"sars-, cov-2, virus"
20569,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.12,"an, intermediate, species, and, humans, by"
20570,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.12,"that, of, sars-cov-2, and, more, likely"
20571,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.12,"the, covid-19, virus, in, and, of"
20572,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.12,"in, the, december, 2019, and, of"
20573,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.12,"isolated, and, in, patients, december, 2019"
20574,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",COVID-19 is a zoonotic virus,0.12,"a, is, virus"
20575,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",COVID-19 is a zoonotic virus,0.12,"covid-19, a, is"
20576,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.12,"the, that, coronaviruses, are, to, and"
20577,"Bats are natural hosts of many of the known  

coronaviruses","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.12,"are, the, coronaviruses"
20578,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.12,"a, coronavirus, the, pangolin, to, with"
20579,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.12,"to, could, a, of, bats, the, and, with, coronaviruses"
20580,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.12,"the, highly, coronavirus, that, coronaviruses, to"
20581,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.12,"analysis, sequence, the, of, coronavirus, that"
20582,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.12,"the, that, of, structure, sars-cov-2, is"
20583,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.12,"that, the, as, very, to, bat"
20584,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.12,"through, that, the, and, from, a"
20585,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.12,"the, a, natural, genome, from, and"
20586,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.12,"the, by, from, a, and, on"
20587,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.12,"human, zoonotic, in"
20588,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.12,"isolated, patients, in, december, 2019, and"
20589,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.12,"a, and, isolated, in, province,, china"
20590,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.12,"a, bat, the, of, sars-cov-2, from"
20591,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.12,"isolated, and, in, a, province,, china"
20592,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.12,"has, the, sequence, of, with, sars-cov-2"
20593,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.12,"the, of, and, virus, from, a, sequence, in, with"
20594,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.12,"revealed, a, of, in, the, china"
20595,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.12,"of, a, the, virus, bat, and"
20596,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.12,"sars-cov-2, genome, and, a, the, of"
20597,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.12,"bat, sars-cov-2, in"
20598,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.12,"this, that, sars-cov-2"
20599,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.12,"of, the, sequence, analysis, that, coronavirus"
20600,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.12,"the, most, likely, hosts, of, intermediate"
20601,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.12,"a, coronavirus, in, the, that, of"
20602,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.12,"were, a, intermediate, for, the, in"
20603,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.12,"the, in, a, for, of, based, mammals, on, most, likely, that, were"
20604,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.12,"coronavirus, isolated, from, a, pangolin, intermediate, hosts, in, the"
20605,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.12,"that, sars-cov-2, a, the, of, genome"
20606,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.12,"coronaviruses, are, a, of, viruses, among"
20607,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.12,"are, of, animal"
20608,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.12,"of, the, are"
20609,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.12,"the, and, animal"
20610,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.12,"the, animal, of"
20611,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.12,"the, of, most, likely, intermediate, hosts"
20612,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","Bats are natural hosts of many of the known  

coronaviruses",0.12,"coronaviruses, are, the"
20613,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.12,"is, to, be, between, bat, and"
20614,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.12,"the, of, to, that, serve, as"
20615,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.12,"the, intermediate, to"
20616,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.12,"most, to, intermediate"
20617,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.12,"hypothesis, the, of, that, to, virus"
20618,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.12,"that, with, sars-, cov-2, at, to"
20619,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.12,"in, the, of, a, coronavirus, that"
20620,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.12,"a, of, the, at, that, to"
20621,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.12,"to, that, sars-, cov-2, the, of"
20622,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.12,"are, and, to"
20623,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.12,"that, of, a"
20624,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.12,"the, of, with"
20625,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.12,"the, of, human"
20626,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.12,"the, with, human"
20627,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.12,"of, the, sars-cov-2, isolated, in, from"
20628,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.12,"bat, also, the"
20629,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.12,"be, the, of"
20630,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.12,"the, of, animal"
20631,"This suggests that the BANAL series may be able to directly infect  

humans.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.12,"that, the, be"
20632,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.12,"the, origin, of"
20633,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.12,"between, and, sars-cov-2"
20634,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.12,"and, that, of, in, many, pangolin"
20635,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.12,"on, the, of, and, that, was"
20636,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.12,"within, of, and, a, in, the"
20637,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.12,"the, of, sars-cov-2, and, as, a"
20638,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.12,"the, hypothesis, that, virus, to, of"
20639,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.12,"the, that, virus, found, in, which"
20640,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.12,"we, believe, the"
20641,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.12,"human, in, zoonotic"
20642,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.12,"are, zoonotic, in"
20643,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.12,"studies, to, and, a, the, of"
20644,"t some virus detected in pangolins 

were capable of infecting humans.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.12,"detected, in, of"
20645,zoonotic origins of SARS-CoV-2 by natural evolution,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.12,"zoonotic, of, sars-cov-2"
20646,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.12,"to, in, recent, sars-cov-2, the, and"
20647,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.12,"the, genome, natural, and, from, a"
20648,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.12,"to, mers-cov, sars-cov"
20649,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.12,"similarity, to, sars-cov-2"
20650,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.12,"in, the, a, were, intermediate, for"
20651,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.12,"the, with, genetic, sars-cov-2, it, for"
20652,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.12,"a, of, be, the, possible, bat"
20653,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.12,"in, a, that, the, more, to"
20654,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.12,"the, that, to, more, in, is, than, of, it, and, not, sars-cov-2"
20655,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.12,"this, that, a, the, virus, than, human, with, of, in, not, to"
20656,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.12,"the, that, more, for, virus, than"
20657,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.12,"in, with, the, and, to, that, sars-cov-2, is, of"
20658,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.12,"is, that, sars-cov-2, of, a, coronavirus"
20659,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.12,"sars-cov-2, similarity, with"
20660,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.12,"sars-cov-2, a, similarity, found, in, bat"
20661,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.12,"the, to, discovered"
20662,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.12,"is, that, the"
20663,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.12,"to, is, the"
20664,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.12,"that, sars-cov-2, to"
20665,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.12,"the, sars-cov-2, is"
20666,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.12,"human, with, the"
20667,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.12,"the, of, is, a, that, not"
20668,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.12,"that, been, by, a, of, the"
20669,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.12,"et, al., (2020), sars-cov-2, the, in"
20670,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.12,"(2020), the, sars-cov-2, and, has, from"
20671,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.12,"sars-cov-2, and, the, of, from, in"
20672,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.12,"has, sequence, sars-cov-2, with, the, of"
20673,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.12,"coro-, navirus, from, bats, by, and"
20674,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.12,"and, from, in, found, to, sars-cov-2,, the, is, bats"
20675,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.12,"that, sars-cov-2, a, animal, and, or"
20676,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.12,"the, of, sars-cov-2, and, animal, intermediate"
20677,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.12,"sars-cov-2, to, be, and, the, transmission"
20678,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.12,"that, the, and, may, be, to"
20679,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.12,"the, sars-cov-2, with, other, to, be"
20680,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.12,"are, the, variants, and, in, that, ability, to, use"
20681,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.12,"the, early, have, been, in, that"
20682,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.12,"the, in, a, to, and, laboratory"
20683,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.12,"in, a, sars-cov-2, to, that, common"
20684,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.12,"the, obtained, sars-cov-2, to, also, and"
20685,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.12,"the, to, intermediate"
20686,"The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.12,"the, zoonotic, host"
20687,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.12,"the, spillover, from"
20688,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.12,"sars-cov-2, in, bat"
20689,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.12,"sars-cov-2, similarity, to"
20690,"This suggests that the BANAL series may be able to directly infect  

humans.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.12,"banal, series, to"
20691,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.12,"to, in, sars-cov-2"
20692,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.12,"in, the, of, for, that, sars-cov-2"
20693,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.12,"coronaviruses, and, a, to, the, bats, could, of, with"
20694,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.12,"a, of, that, sars-cov-2, the, virus"
20695,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.12,"a, of, the, sars-cov-2, genome, that"
20696,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.12,"the, sars-cov-2, of, virus, is, to"
20697,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.12,"the, bats, viral, reservoirs, and, in, of, species, horseshoe, (rhinolophus, bats), or"
20698,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.12,"sars-cov-2, the, that, to, coronaviruses, including"
20699,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.12,"are, to, the, in, and, that"
20700,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.12,"the, discovered, to"
20701,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.12,"the, in, and, a, within, of"
20702,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.12,"a, bat, of, by, the, in"
20703,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.12,"the, virus, is, similar, to, and, that, its, in"
20704,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.12,"sars-cov-2, of, have, to, from, closest"
20705,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.12,"to, sars-cov-2, highest, similarity, the, sars-cov-2,"
20706,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.12,"the, and, are, similar, to, sars-"
20707,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.12,"with, a, and, at, the, in"
20708,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.12,"the, was, to, are, closely, related, in, by, it, and, sars-cov-2, at"
20709,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.12,"the, genome, to, and, was, a"
20710,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.12,"a, to, sars-cov-2, by, the, and"
20711,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.12,"a, in, and, to, which, the"
20712,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.12,"sars-cov-2, was, to, which, the, in"
20713,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.12,"in, with, the, by, and, to, sars-cov-2, are, sars-"
20714,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.12,"and, in, to, closely, related, the, sars-, are, sars-cov-2"
20715,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.12,"the, is, that, of, are, and"
20716,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.12,"of, affinity, binds, to, human, ace2, have, that, the"
20717,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.12,"to, the, rbd, that, ace2, of"
20718,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.12,"to, that, the, of, have, than"
20719,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","This suggests that the BANAL series may be able to directly infect  

humans.",0.12,"the, to, that"
20720,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","This suggests that the BANAL series may be able to directly infect  

humans.",0.12,"the, that, be"
20721,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","This suggests that the BANAL series may be able to directly infect  

humans.",0.12,"this, that, the"
20722,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.12,"a, to, sars-cov-2, the, recombination, and"
20723,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.12,"recent, sars-cov-2, to, the, in, and"
20724,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.12,"is, sars-cov-2, and, the, that, in"
20725,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.12,"to, from, and, with, the, of"
20726,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.12,"on, the, by, and, from, a"
20727,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.12,"was, suggested, that, the, patients, with, in, have, live, or, a, of"
20728,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.12,"in, the, of, virus, than, not, to, that, with, human, this, a"
20729,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.12,"a, sequence, and, with, the, of, virus, from, in"
20730,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.12,"in, a, of, for, were, found, to, with, that"
20731,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.12,"to, the, of, and, from, virus, palm, civet, human"
20732,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.12,"the, viral, reservoirs, or, species, of, horseshoe, bats, (rhinolophus, bats), in, and"
20733,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.12,"a, it, that, the, also, ace2, and, mechanism, for, to, used, by"
20734,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.12,"the, in, for, of, identified, were, to, similarly,, by, chinese, and, a, all, had, an"
20735,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.12,"in, the, a, was, that, are, animals, to, time, and, with, for"
20736,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.12,"based, on, in, the, of, a, that, mammals, were, most, likely, for"
20737,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.12,"the, of, with, huanan, seafood, market, in, wuhan, hubei"
20738,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.12,"an, had, to, a, in, chinese, for, the, by, similarly,, identified, all, were, of, and"
20739,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.12,"the, cases, that, be, infected, with, sars-cov-2, were, at, market,, by, there"
20740,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.12,"on, january, the, a, and, to"
20741,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.12,"a, shows, the, in, samples, collected"
20742,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.12,"the, of, 19, to, and, in"
20743,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.12,"the, origin, of, to, between, and"
20744,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.12,"the, between, and, of, is, to"
20745,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.12,"the, that, a, in, animal, this"
20746,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.12,"at, the, of, covid-19, with, genomic"
20747,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.12,"the, of, with, that, and, is"
20748,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.12,"that, seafood, market, in, the, first"
20749,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.12,"the, of, and, are, is, that"
20750,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.12,"the, is, to, sars-cov-2, that, virus"
20751,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","expended to make the simple point 

that COVID-19 had a natural origin.",0.12,"the, natural, a"
20752,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","expended to make the simple point 

that COVID-19 had a natural origin.",0.12,"the, a, that"
20753,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","expended to make the simple point 

that COVID-19 had a natural origin.",0.12,"a, the, to"
20754,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","expended to make the simple point 

that COVID-19 had a natural origin.",0.12,"that, the, natural"
20755,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.12,"we, as, the"
20756,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.12,"a, of, and, the, new, in"
20757,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.12,"in, the, of, to, and, a"
20758,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.12,"in, a, and, which, to, the"
20759,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.12,"a, the, genomic, with, bat, that"
20760,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.12,"a, shows, samples, collected, in, the"
20761,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.12,"that, sars-cov-2, or"
20762,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.12,"the, that, of, not, is, a"
20763,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.12,"of, that, is, most, to, the"
20764,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.12,"is, coronavirus, it"
20765,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.12,"that, a, of"
20766,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.12,"that, of, is, a, coronavirus, sars-cov-2"
20767,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","atural  

selection in an animal host before zoonotic  

transfer;",0.12,"zoonotic, an, animal"
20768,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.12,"to, the, sars-, reservoir, is, for"
20769,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.12,"the, of, that, serve, as, to"
20770,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.12,"to, the, that, bats, hosts, for"
20771,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.12,"to, is, a, that, from, the"
20772,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.12,"that, the, rbd, of, to, ace2"
20773,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.12,"the, and, polybasic, cleavage, that, of"
20774,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.12,"the, of, and, in, we, that, not, is, plausible"
20775,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.12,"and, the, of, that, polybasic, cleavage"
20776,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.12,"and, that, of, the, is, scenario"
20777,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.12,"observed, that, the, sars-cov-2, and, is"
20778,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.12,"we, that, the, sars-cov-2, and, is"
20779,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","In the 

case of MERS, dromedaries were the principal host.",0.12,"were, the, in"
20780,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","In the 

case of MERS, dromedaries were the principal host.",0.12,"in, of, the"
20781,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.12,"the, first, was, not, to, that"
20782,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.12,"of, that, the, covid-19, bat, a"
20783,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.12,"animal, a, this, in, the, that"
20784,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.12,"and, to, 19, of, in, the"
20785,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.12,"to, the, and, humans,, which, from"
20786,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.12,"animals, to, the, covid-19, which, and"
20787,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",The COVID-19 most likely developed from bat origin coronaviruses,0.12,"from, the, bat"
20788,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",The COVID-19 most likely developed from bat origin coronaviruses,0.12,"the, bat, from"
20789,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",The COVID-19 most likely developed from bat origin coronaviruses,0.12,"from, the, likely"
20790,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.12,"that, the, of, a, bat, covid-19"
20791,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.12,"the, of, origin, a, as, diversity"
20792,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.12,"and, analysis, that, of, in, intermediate"
20793,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.12,"and, virus, the, covid-19, in, of"
20794,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.12,"of, coronaviruses, a, among, viruses, are"
20795,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.12,"to, most, intermediate"
20796,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.12,"an, in, were"
20797,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.12,"the, in, to"
20798,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.12,"in, be, to"
20799,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.12,"in, the, market"
20800,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.12,"been, in, the, early, that, have"
20801,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.12,"of, and, revealed, that, for, virus"
20802,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.12,"to, the, of, and, bat, virus"
20803,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.12,"the, of, to, is, most, that"
20804,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.12,"the, similar, to, and, that, in"
20805,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.12,"that, of, rhinolophus, the, natural, reservoir"
20806,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.12,"in, the, of, between, and, wildlife"
20807,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.12,"found, in, the, which, that, virus"
20808,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.12,"with, hubei, wuhan, the, huanan, seafood, market, in, of"
20809,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.12,"the, huanan, market, wuhan, in, of, were, with, covid-19"
20810,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.12,"the, first, to, that, was, not"
20811,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.12,"revealed, a, the, of, in, china"
20812,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.12,"the, that, is"
20813,"bats are also important reservoir species for a great 

range of coronaviruses","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.12,"reservoir, species, of"
20814,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.12,"that, rhinolophus, the, natural, reservoir, of"
20815,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.12,"the, between, and, to, be, is"
20816,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.12,"the, and, an, was, humans, by"
20817,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.12,"humans, and, an, intermediate, species, by"
20818,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.12,"bats, of, and, species, are, known, to, be, the"
20819,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.12,"the, between, and, a, of, in"
20820,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.12,"the, in, market"
20821,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.12,"the, of, and, in, between, wildlife"
20822,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.12,"the, sars-cov-2, isolated, in, from, of"
20823,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.12,"sars-cov-2, the, with, at, of, virus"
20824,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","t some virus detected in pangolins 

were capable of infecting humans.",0.12,"of, detected, in"
20825,hese close genetic relations suggest that they all have their ecological origin in bat populations,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.12,"they, their, in"
20826,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.12,"in, were, an"
20827,"preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.12,"of, their, captivity."
20828,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.12,"the, and, also, a, ability, to, not, of, but"
20829,"insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.12,"from, of, such, as, bats,, and"
20830,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.12,"in, the, a, coronavirus, isolated, from, pangolin, intermediate, hosts"
20831,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.12,"bats, the, and"
20832,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.12,"the, in, and"
20833,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.12,"an, not, a, bat, in, from"
20834,The COVID-19 most likely developed from bat origin coronaviruses,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.12,"the, likely, from"
20835,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.12,"several, that, sars-cov-2"
20836,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.12,"to, be, the"
20837,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.12,"the, and, that, of, scenario, is"
20838,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.12,"and, the, of, natural, origin, is"
20839,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.12,"is, origin, the, that, and, scenario"
20840,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.12,"of, the, that, structure, sars-cov-2, is"
20841,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.12,"for, sars-cov-2, it, genetic, with, the"
20842,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.12,"of, the, origin, a, diversity, as"
20843,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.12,"and, natural, origin, of, the, is"
20844,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.12,"sars-cov-2, to, and, the, origin, of"
20845,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.12,"not, from, a, bat, in, an"
20846,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.12,"to, and, that"
20847,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.12,"that, are, sars-cov-2"
20848,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.12,"that, bats, are, more, of, sars-cov-2"
20849,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.12,"bats, are, of, and, several, which, to, that, in"
20850,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.12,"that, the, most"
20851,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.12,"and, that, origin, the, is, scenario"
20852,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.12,"that, the, between, and, ratg13, is"
20853,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.12,"that, to, and, hypothesis, the, origin"
20854,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.12,"be, sars-cov-2, to, other, the, with"
20855,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.12,"also, sars-cov-2, was, the, its, in"
20856,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.12,"was, in, which, to, sars-cov-2, the"
20857,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.12,"the, sars-cov-2, to, obtained, also, and"
20858,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.12,"bats, hosts, and"
20859,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.12,"that, sars-cov-2, bats"
20860,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.12,"are, sars-cov-2, and"
20861,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.12,"the, virus, for, more, than, that"
20862,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.12,"the, that, very, to, bat, as"
20863,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.12,"that, the, bat, as, a, to"
20864,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.12,"a, and, the, of, virus, bat"
20865,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.12,"the, in, at, a, wuhan,, china"
20866,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.12,"et, al., (2020), in, the, sars-cov-2"
20867,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.12,"of, by, bat, a, in, the"
20868,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.12,"genome, was, to, bat, 96.2%, sequence"
20869,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.12,"a, of, the, sars-cov-2, and, in, which, viruses, their"
20870,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.12,"is, a, and, of, the, in"
20871,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.12,"in, the, between, and, an, of"
20872,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.12,"and, related, to, pangolin, in, which"
20873,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.12,"in, for, sars-cov-2, be, with, that"
20874,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.12,"have, that, sars-cov-2, to, with, the"
20875,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.12,"a, that, the, virus, been, by"
20876,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.12,"have, a, that, of, to, and"
20877,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.12,"are, and, the, virus, to, a"
20878,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.12,"the, that, of, been, by, a"
20879,"Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.12,"the, we, as"
20880,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.12,"sars-cov-2, the, and, in, that, of"
20881,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.12,"in, a, of, sars-cov-2, with, that"
20882,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.12,"sars-cov-2, to, bat"
20883,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.12,"the, closest, to, that, in, and"
20884,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.12,"that, could, and, are, the, genome"
20885,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.12,"the, results, for, that, be, hosts"
20886,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.12,"the, could, in, or, to, and"
20887,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.12,"the, to, that, bats, hosts, for"
20888,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.12,"and, more, likely, that, of, sars-cov-2"
20889,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.12,"(2020), the, sars-cov-2, has, from, and"
20890,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.12,"in, is, that, the, and, sars-cov-2"
20891,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.12,"have, the, sars-cov-2, is, to, bat"
20892,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.12,"in, the, of, is, to, that, sars-cov-2, with, and"
20893,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.12,"in, by, with, sars-, and, are, to, sars-cov-2, the"
20894,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.12,"observed, sars-cov-2, the, and, that, is"
20895,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.12,"is, the, that, ratg13, between, and"
20896,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.12,"sars-cov-2, that, this"
20897,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.12,"sars-cov-2, that, are"
20898,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.12,"bats, are, more, that, of, sars-cov-2"
20899,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.12,"we, sars-cov-2, the, and, that, is"
20900,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.12,"sars-cov-2, are, cov, and, the, origin"
20901,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.12,"that, in, sars-cov-2"
20902,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.12,"that, bats, sars-cov-2"
20903,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.12,"have, that, the, of, to, than"
20904,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.12,"wuhan, the, in, of, and, china"
20905,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.12,"genome, a, sars-cov-2, and, the, of"
20906,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.12,"studies, the, of, to, a, and"
20907,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.12,"and, to, the, of, sars-cov-2, origin"
20908,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.12,"hypothesis, to, origin, the, that, and"
20909,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.12,"cov, and, the, origin, are, sars-cov-2"
20910,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.12,"has, to, that"
20911,"a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.12,"similarity, with, sars-cov-2"
20912,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.12,"the, to, sars-cov, with, of, and"
20913,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.12,"with, the, of, sars-cov-2, and, sars-cov"
20914,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.12,"the, is, sars-cov-2"
20915,"no modifications were  

recorded for nonstructural proteins NSP7, NSP13  

and the structured and accessory proteins p6 and 8b.","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.12,"for, and, the"
20916,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.12,"between, sars-cov-2, and"
20917,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.12,"a, of, and, that, the, bats"
20918,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.12,"the, of, for, that, and, a"
20919,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.12,"in, to, and"
20920,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.12,"to, sars-cov-2, in"
20921,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.12,"and, are, sars-cov-2"
20922,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.12,"are, the, sars-cov-2"
20923,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.12,"sars-cov-2, the, of, that, to, closest"
20924,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.12,"and, of, between, in, an, the"
20925,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.12,"of, the, however,, that, not, bats"
20926,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.12,"sars-cov-2, is, virus, that, to, the"
20927,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.12,"the, of, that, to, this, origin"
20928,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.12,"to, sars-cov-2,, highest, similarity, sars-cov-2, the"
20929,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.12,"the, most, that"
20930,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.12,"sars-cov-2, the, bat-sl-cov"
20931,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.12,"sars-cov-2, of, animal, and, the, intermediate"
20932,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.12,"the, between, sars-cov-2, and, be, a"
20933,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.12,"bat-sl-cov, the, sars-cov-2"
20934,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.12,"a, that, the, sars-cov-2, for, is"
20935,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.12,"in, a, of, to, that, were, being, for, found"
20936,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.12,"a, that, to, common, in, sars-cov-2"
20937,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.12,"for, of, were, that, a, found, in, with, to"
20938,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.12,"that, be, for, sars-cov-2, in, with"
20939,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.12,"bats, natural, hosts, of, cov,, and"
20940,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.12,"several, in, bats, which, are, to, that, of, and"
20941,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.12,"the, has, genome, which, identity, with"
20942,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.12,"in, the, of, that, sars-cov-2, to"
20943,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.12,"the, and, in, found, bats, from, is, to, sars-cov-2,"
20944,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.12,"in, closely, related, sars-, and, are, to, sars-cov-2, the"
20945,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.12,"not, a, of, but, also, and, the, ability, to"
20946,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.12,"that, is, related, to, bat, possible"
20947,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.12,"analysis, the, to, be, with, rbd, of, and, infection"
20948,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.12,"coronaviruses, to, sars-cov-2, the, bat, and"
20949,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.11971831,"the, was, also, to, a, live, virus, that, with, this, human, sars, in, of, isolated, at, an"
20950,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.11971831,"this, that, sars, a, the, virus, was, an, human, with, of, in, at, also, isolated, to, live"
20951,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.119565217,"and, the, of, bat, to, a, with, that, for, which, virus"
20952,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.119565217,"and, the, of, to, are, bats, they, in, which, virus, is"
20953,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.119565217,"the, virus, for, a, of, which, to, with, that, and, bat"
20954,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.119565217,"are, they, in, to, is, of, the, virus, which, bats, and"
20955,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.119565217,"is, a, virus, that, with, infected, on, to, the, most, for"
20956,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.119565217,"the, to, a, for, with, is, on, most, that, infected, virus"
20957,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.119402985,"and, in, to, closely, related, are, very, sars-cov-2"
20958,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.119402985,"the, and, amino, acid, in, found, is, to"
20959,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.119402985,"in, a, other, and, which, to, sars-cov-2, the"
20960,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.119402985,"a, of, to, the, that, was, is, found"
20961,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.119402985,"is, the, with, thus, that, bats, are, for"
20962,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.119402985,"to, that, the, virus, bats, be, of, recombination"
20963,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.119402985,"in, a, to, the, virus, that, was, is"
20964,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.119402985,"had, and, to, was, the, that, in, a"
20965,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.119402985,"on, in, the, that, of, were, to, market"
20966,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.119402985,"natural, hosts, and, to, that, cause, disease, as"
20967,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.119402985,"that, and, for, to, humans, the, in, with"
20968,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.119402985,"the, pandemic, of, zoonotic, sars-cov-2, a, progenitor, in"
20969,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.119402985,"sars-cov-2, may, also, in, a, of, that, the"
20970,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.119402985,"was, found, that, the, of, is, to, a"
20971,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.119402985,"the, of, to, is, likely, that, as, for"
20972,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.119402985,"the, and, that, virus, a, with, as, to"
20973,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.119402985,"and, from, to, that, the, of, coronavirus, is"
20974,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.119402985,"a, and, from, bat, to, which, that, coronavirus"
20975,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.119402985,"to, the, coronavirus, of, and, that, a, covid-19"
20976,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.119402985,"to, from, a, in, bats, the, and, that"
20977,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.119402985,"to, the, in, bats, of, and, animals, covid-19"
20978,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.119402985,"the, sequence, of, novel, that, bat, as, and"
20979,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.119402985,"the, of, to, with, human, host,, and, a"
20980,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.119402985,"novel, sequence, bat, that, the, of, as, and"
20981,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.119402985,"in, a, of, that, the, intermediate, hosts, for"
20982,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.119402985,"that, intermediate, hosts, for, based, on, the, in"
20983,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.119402985,"are, viruses, to, the, genome, in, and, that"
20984,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.119402985,"a, which, to, that, coronavirus, from, and, bat"
20985,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.119402985,"that, is, bat, a, high, from, species, as"
20986,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.119402985,"study, et, al., was, that, the, to, of"
20987,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.119402985,"in, the, of, was, a, that, taken, and"
20988,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.119402985,"of, and, a, which, to, as, human, covs"
20989,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.119402985,"from, a, of, bats, the, and, it, with"
20990,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.119402985,"had, and, to, was, by, the, sars-cov-2, been"
20991,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.119402985,"and, a, to, the, of, human, with, host,"
20992,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.119402985,"and, from, in, shameli, were, the, of, sars-cov-2"
20993,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.119402985,"et, al., the, sars-cov-2, to, high, in, of"
20994,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.119402985,"the, amino, acid, and, to, is, found, in"
20995,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.119402985,"the, of, sars-cov-2, to, is, result, natural, that"
20996,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.119402985,"in, also, the, of, that, a, sars-cov-2, may"
20997,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.119402985,"in, the, of, a, that, intermediate, hosts, for"
20998,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.119402985,"in, the, that, to, humans, and, with, for"
20999,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.119402985,"based, on, in, the, that, intermediate, hosts, for"
21000,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.119402985,"to, sars-cov-2, in, the, key, rbd, that, for"
21001,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.119402985,"that, the, in, bats, and, to, from, a"
21002,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.119402985,"with, the, of, bats, a, it, from, and"
21003,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.119402985,"of, southeast, asia, and, a, living, in, the"
21004,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.119402985,"a, of, the, pandemic, sars-cov-2, zoonotic, in, progenitor"
21005,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.119402985,"a, of, in, living, the, southeast, asia, and"
21006,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.119402985,"the, sars-cov-2, and, which, to, a, in, other"
21007,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.119402985,"the, of, to, is, likely, that, reservoir, for"
21008,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.119402985,"the, virus, as, a, that, with, and, to"
21009,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.119402985,"a, virus, sequence, that, with, the, in, collected"
21010,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.119402985,"the, was, in, and, that, taken, a, of"
21011,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.119402985,"that, were, related, to, found, in, and, from"
21012,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.119402985,"and, samples, the, it, would, be, likely, that, its, of, in, this, study, from, a, by"
21013,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.119402985,"had, from, its, reservoir, as, and, it, multiple, to, this, by, the, of, that, in, a"
21014,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.119402985,"in, the, of, would, a, study, by, samples, be, and, that, likely, from, this, it, its"
21015,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.119402985,"on, the, of, that, were, to, market, in"
21016,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.119402985,"in, found, that, from, were, to, and, related"
21017,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.119402985,"the, of, a, which, huge, to, in, and"
21018,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.119402985,"the, that, virus, collected, a, sequence, in, with"
21019,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.119402985,"the, of, to, that, sars-cov-2, is, result, natural"
21020,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.119402985,"of, to, the, likely, that, is, for, as"
21021,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.119402985,"the, of, is, for, likely, reservoir, to, that"
21022,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.119402985,"that, for, sars-cov-2, to, the, key, in, rbd"
21023,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.119402985,"is, a, from, bat, species, as, high, that"
21024,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.119402985,"the, covid-19, a, of, to, that, coronavirus, and"
21025,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.119402985,"in, animals, to, of, the, covid-19, bats, and"
21026,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.119402985,"a, huge, of, in, and, to, which, the"
21027,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.119402985,"on, the, of, in, receptor, binding, domain, protein"
21028,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.119402985,"the, of, to, that, has, been, and, a"
21029,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.119402985,"a, the, to, that, in, had, and, was"
21030,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.119402985,"to, had, been, by, and, was, the, sars-cov-2"
21031,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.119402985,"in, the, of, a, to, as, by, had, and, that, from, this, it, its, reservoir, multiple"
21032,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.119402985,"et, al., the, high, of, to, sars-cov-2, in"
21033,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.119402985,"the, study, of, et, al., that, was, to"
21034,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.119402985,"in, the, of, receptor, binding, domain, protein, on"
21035,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.119402985,"other, sequences, are, pangolin, cov, and, the, of"
21036,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.119402985,"the, genome, and, that, in, viruses, are, to"
21037,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.119402985,"bats, are, for, the, is, thus, with, that"
21038,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.119402985,"of, the, cov, and, are, sequences, other, pangolin"
21039,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.119402985,"bats, the, recombination, of, virus, be, that, to"
21040,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.119402985,"disease, as, hosts, that, cause, natural, to, and"
21041,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.119402985,"of, human, covs, to, a, and, which, as"
21042,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.119402985,"and, sars-cov-2, are, closely, related, to, in, very"
21043,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.119402985,"the, is, to, that, of, and, coronavirus, from"
21044,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.119402985,"the, of, from, shameli, and, were, in, sars-cov-2"
21045,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.119266055,"that, palm, civets, were, infected, from, in, the, a, at, and, of, moreover,"
21046,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.119266055,"in, the, of, palm, civets, a, at, that, from, infected, were, moreover,, and"
21047,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.119047619,"that, naturally, of, the, sarbecovirus"
21048,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.119047619,"to, bat, and, a, very"
21049,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.119047619,"a, genetic, to, sars-cov-2, and"
21050,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.119047619,"sars-cov-2, to, viruses, in, and"
21051,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.119047619,"this, the, of, and, wild"
21052,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.119047619,"an, reservoir, coronaviruses, bat, species"
21053,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.119047619,"bats, the, from, or, in"
21054,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.119047619,"such, have, and, in, to"
21055,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.119047619,"sars-cov-2, to, bats, in, of"
21056,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.119047619,"more, of, bats, in, and"
21057,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.119047619,"bats, and, of, species, by"
21058,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.119047619,"sequences, of, from, and, were"
21059,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.119047619,"the, and, are, many, to"
21060,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.119047619,"are, and, the, to, sars"
21061,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.119047619,"to, the, sars-, cov-2, and"
21062,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.119047619,"evolution, for, is, and, a"
21063,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.119047619,"are, in, of, the, bats"
21064,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.119047619,"human, with, the, of, infection"
21065,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.119047619,"a, origin, of, sars-cov-2, by"
21066,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.119047619,"that, of, sars-cov-2, coronavirus, been"
21067,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.119047619,"any, from, it, have, been"
21068,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.119047619,"any, have, been, it, from"
21069,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.119047619,"coronavirus, is, from, have, been"
21070,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.119047619,"covid-19, would, a, in, the, that, sars-cov-2, human, or, for"
21071,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.119047619,"is, that, virus, a, and"
21072,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.119047619,"with, that, and, sars-cov-2, a"
21073,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.119047619,"the, and, many, are, to"
21074,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.119047619,"to, the, viruses, and, of"
21075,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.119047619,"of, viruses, and, to, the"
21076,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.119047619,"the, of, that, these, viruses"
21077,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.119047619,"of, to, the, emergence, these"
21078,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.119047619,"the, genome, that, sars-cov-2, natural"
21079,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.119047619,"the, to, as, sars-cov-2, bat"
21080,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.119047619,"that, sars-cov-2, the, with, to"
21081,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.119047619,"that, sars-cov, is, of, bat"
21082,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.119047619,"been, as, of, and, host"
21083,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.119047619,"has, been, of, as, and"
21084,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.119047619,"and, are, of, the, a"
21085,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.119047619,"the, of, a, natural, and"
21086,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.119047619,"genome, to, the, covid-19, virus"
21087,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.119047619,"bat, overall, genome, sars-cov-2, ratg13"
21088,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.119047619,"bat, might, the, sars-cov-2, and"
21089,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.119047619,"in, of, were, as, intermediate"
21090,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.119047619,"known, and, in, the, to"
21091,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.119047619,"the, of, sars-cov-2, is, in"
21092,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.119047619,"human, that, a, of, the"
21093,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.119047619,"of, the, in, that, a"
21094,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.119047619,"and, been, as, host, of"
21095,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.119047619,"the, to, and, that, was"
21096,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.119047619,"that, was, and, in, a"
21097,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.119047619,"that, the, similarity, and, is"
21098,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.119047619,"that, to, and, a, the"
21099,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.119047619,"of, were, in, intermediate, as"
21100,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.119047619,"as, to, the, of, spillover"
21101,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.119047619,"the, phylogenetic, sars-cov-2, of, to"
21102,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.119047619,"and, has, been, as, of"
21103,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.119047619,"had, been, of, the, probably"
21104,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.119047619,"the, of, that, is, to"
21105,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.119047619,"the, of, a, and, sars-cov-2"
21106,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.119047619,"to, sars-cov-2, the, be, of"
21107,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.119047619,"be, a, the, sars-cov-2, animal"
21108,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.119047619,"bats, of, species, by, and"
21109,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.119047619,"t, the, that, bats, are"
21110,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.119047619,"may, of, and, the, hosts"
21111,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.119047619,"the, to, intermediate, hosts, and"
21112,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.119047619,"the, from, intermediate, as, to"
21113,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.119047619,"is, in, wuhan, from, to"
21114,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.119047619,"was, to, which, the, in"
21115,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.119047619,"with, the, of, that, is"
21116,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","civet cats and raccoon dogs  

are the intermediate hosts",0.119047619,"and, cats, the, intermediate, hosts"
21117,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.119047619,"and, are, to, of, the"
21118,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.119047619,"sars-cov-2, in, to, bats, of"
21119,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.119047619,"is, bats, the, sars-cov-2, to"
21120,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.119047619,"the, and, that, which, by"
21121,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.119047619,"that, the, in, and, a"
21122,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.119047619,"and, by, a, in, the"
21123,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.119047619,"the, hypothesis, was, that, a"
21124,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.119047619,"the, to, that, of, from"
21125,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.119047619,"a, the, spillover, that, to"
21126,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.119047619,"that, sars-cov-2, the, genomic, through"
21127,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.119047619,"and, bat, ratg13, the, of"
21128,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.119047619,"the, of, sars-cov-2, result, that"
21129,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.119047619,"other, events, coronaviruses,, with, sars-cov-2"
21130,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.119047619,"the, a, that, bat, to"
21131,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.119047619,"humans, from, the, of, sars-cov-2"
21132,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.119047619,"the, from, market, animals, humans"
21133,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.119047619,"the, most, of, sars-cov-2, intermediate"
21134,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.119047619,"probable, of, sars-cov-2, at, the"
21135,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.119047619,"the, that, to, animals, market"
21136,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.119047619,"the, to, that, of, and"
21137,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.119047619,"the, that, to, of, and"
21138,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.119047619,"the, is, a, of, and"
21139,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.119047619,"the, of, and, in, with"
21140,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.119047619,"the, is, of, a, in"
21141,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.119047619,"the, by, et, from, a"
21142,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.119047619,"the, was, taken, a, of"
21143,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.119047619,"genomic, that, sars-cov-2, the, reservoir"
21144,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.119047619,"that, the, market, in, and"
21145,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.119047619,"the, likely, reservoir, sars-cov-2, and"
21146,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.119047619,"genomic, that, the, in, and"
21147,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.119047619,"that, the, sars-cov-2, and, likely"
21148,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.119047619,"that, sars-cov-2, the, at, and"
21149,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.119047619,"and, sars-cov-2, to, in, of"
21150,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.119047619,"a, published, in, the, of"
21151,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.119047619,"was, that, the, of, to"
21152,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.119047619,"the, to, that, and, was"
21153,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.119047619,"the, was, that, and, to"
21154,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.119047619,"is, the, most, closely, related, to, sars-cov-2, known, in, wiv’s"
21155,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.119047619,"there, at, that, the, as"
21156,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.119047619,"the, cases, that, market,, by"
21157,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.119047619,"the, market, animals, that, to"
21158,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.119047619,"the, genome, to, that, a"
21159,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.119047619,"a, genetic, to, that, the"
21160,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.119047619,"a, the, genome, that, two"
21161,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.119047619,"that, of, from, to, is, a, found, in, analysis, the"
21162,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.119047619,"a, at, in, that, the, virus, is, of, were, found"
21163,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.119047619,"is, to, in, from, wuhan"
21164,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.119047619,"an, is, to, that, from"
21165,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.119047619,"is, that, to, a, humans."
21166,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.119047619,"a, role, of, the, by, that, or, other, have, to"
21167,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.119047619,"of, as, from, bats,, and"
21168,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.119047619,"that, was, and, a, on"
21169,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.119047619,"the, to, that, was, virus"
21170,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.119047619,"and, that, a, the, virus"
21171,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.119047619,"the, and, that, a, with"
21172,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.119047619,"that, the, similarity, and, bat"
21173,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.119047619,"that, the, were, and, huanan"
21174,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.119047619,"other, that, cov, and, origin"
21175,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.119047619,"and, to, bat, a, very"
21176,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.119047619,"the, and, bat, that, to"
21177,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.119047619,"the, that, a, genome, to"
21178,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.119047619,"the, to, that, and, coronavirus"
21179,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.119047619,"the, that, to, a, and"
21180,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.119047619,"the, covid-19, and, a, to"
21181,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.119047619,"a, and, the, that, to"
21182,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.119047619,"the, of, be, to, animal"
21183,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.119047619,"the, published, in, a, of"
21184,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.119047619,"a, with, the, of, in"
21185,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.119047619,"were, a, with, the, in"
21186,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.119047619,"to, the, that, of, from"
21187,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.119047619,"and, the, of, which, is"
21188,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.119047619,"that, the, and, an, of"
21189,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.119047619,"the, and, sars-cov-2, is, to"
21190,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.119047619,"that, bats, the, a, and"
21191,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.119047619,"sars-cov-2, and, pangolin, to, the"
21192,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.119047619,"the, virus, which, covid-19, has"
21193,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.119047619,"from, a, virus, that, bat"
21194,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.119047619,"the, have, shown, sars-cov-2, to"
21195,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.119047619,"have, the, to, from, a"
21196,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.119047619,"to, the, sars-cov-2, has, from"
21197,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.119047619,"the, from, a, to, with"
21198,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.119047619,"of, similar, to, the, and"
21199,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.119047619,"and, sars-cov-2, to, a, genetic"
21200,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.119047619,"genetic, the, that, a, to"
21201,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.119047619,"of, the, virus, and, available"
21202,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.119047619,"the, and, of, a, to"
21203,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.119047619,"intermediate, hosts, to, and, the"
21204,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.119047619,"between, and, the, of, bat"
21205,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.119047619,"the, of, human, to, and"
21206,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.119047619,"and, to, the, of, is"
21207,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.119047619,"the, and, by, which, that"
21208,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.119047619,"the, shown, to, have, sars-cov-2"
21209,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.119047619,"the, was, transmitted, to, by"
21210,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.119047619,"to, humans, is, and, the"
21211,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.119047619,"suggesting, sars-cov-2, the, and, an"
21212,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.119047619,"the, was, in, and, a"
21213,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.119047619,"bats, and, was, in, the"
21214,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.119047619,"a, the, in, wuhan,, china"
21215,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.119047619,"a, from, the, to, have"
21216,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.119047619,"the, bats, are, in, of"
21217,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.119047619,"the, infectious, of, are, and"
21218,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.119047619,"in, to, that, has, been"
21219,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.119047619,"the, that, at, as, there"
21220,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.119047619,"evidence, that, the, of, as"
21221,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.119047619,"that, were, to, in, and"
21222,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.119047619,"that, the, and, more, likely"
21223,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.119047619,"and, sars-cov, the, virus, in"
21224,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.119047619,"the, and, in, that, is"
21225,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.119047619,"that, the, of, may, to"
21226,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.119047619,"the, genomic, sars-cov-2, reservoir, that"
21227,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.119047619,"the, could, be, to, sars-cov-2"
21228,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.119047619,"the, first, that, was, not"
21229,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.119047619,"the, in, seafood, market, china"
21230,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.119047619,"that, the, be, a, of"
21231,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.119047619,"bats, the, reservoirs, viruses, of"
21232,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.119047619,"the, that, is, previously, used"
21233,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.119047619,"for, and, that, the, sars-cov-2"
21234,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.119047619,"the, coronavirus, to, human, than"
21235,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.119047619,"the, bat, animal, for, sars-cov-2."
21236,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.119047619,"several, to, sars-cov-2, and, the"
21237,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.119047619,"is, the, virus, to, sars-cov-2"
21238,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.119047619,"the, pangolin, in, a, of"
21239,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.119047619,"that, of, is, bat, sars-cov"
21240,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.119047619,"genetic, of, sars-cov, and, bats"
21241,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.119047619,"the, virus, covid-19, has, which"
21242,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",Many of these CoVs can infect several animal species as well,0.119047619,"of, species, as, can, infect"
21243,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.119047619,"virus, a, to, that, from"
21244,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.119047619,"to, human, is, a, that"
21245,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.119047619,"that, is, a, from, animal"
21246,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.119047619,"from, is, to, in, the"
21247,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.119047619,"bat, have, origin, they, all"
21248,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.119047619,"the, in, an, to, virus"
21249,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.119047619,"a, that, sars-cov-2, animal, or"
21250,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.119047619,"the, sars-cov-2, and, is, that"
21251,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.119047619,"there, is, that, species, of"
21252,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.119047619,"to, that, the, virus, of"
21253,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.119047619,"of, available, the, and, virus"
21254,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.119047619,"of, the, genome, with, and"
21255,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.119047619,"virus, genome, the, covid-19, to"
21256,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.119047619,"the, to, appear, with, of"
21257,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.119047619,"and, to, the, viruses, that"
21258,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.119047619,"to, bat, that, the, of"
21259,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.119047619,"that, the, and, bat, sars"
21260,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.119047619,"that, sars-cov-2, genome, the, natural"
21261,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.119047619,"a, the, by, et, from"
21262,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.119047619,"the, that, not, by, a"
21263,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.119047619,"analysis, that, the, genome, a"
21264,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.119047619,"the, from, analysis, that, and"
21265,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.119047619,"analysis, revealed, that, the, and"
21266,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.119047619,"that, the, sars-cov-2, on, comparative"
21267,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.119047619,"in, sars-cov-2, receptor, domain, protein"
21268,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.119047619,"the, covid-19, virus, and, of"
21269,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.119047619,"the, humans, from, animals, market"
21270,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.119047619,"the, market, that, in, and"
21271,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.119047619,"the, which, is, of, and"
21272,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.119047619,"the, is, of, and, transmitted"
21273,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.119047619,"a, that, in, and, was"
21274,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.119047619,"on, was, a, that, and"
21275,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.119047619,"the, to, amino, acid, of"
21276,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.119047619,"the, virus, and, sars-cov, in"
21277,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.119047619,"the, virus, from, identity, with"
21278,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.119047619,"virus, a, that, from, bat"
21279,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.119047619,"sars-cov-2, is, a, that, this"
21280,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.119047619,"that, is, bat, a, from"
21281,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.119047619,"that, may, a, virus, sars-cov-2"
21282,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.119047619,"the, that, a, genome, two"
21283,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.119047619,"sars-cov-2, a, that, and, the"
21284,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.119047619,"of, the, genome, and, with"
21285,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.119047619,"the, that, a, of, and"
21286,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.119047619,"together, and, of, revealed, with"
21287,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.119047619,"infectious, are, of, the, and"
21288,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.119047619,"of, the, that, market,, which"
21289,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.119047619,"that, the, of, wild, animals"
21290,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.119047619,"sars-cov-2, has, the, with, similarity"
21291,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.119047619,"and, is, a, virus, that"
21292,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.119047619,"that, is, a, to, humans."
21293,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.119047619,"and, the, of, is, transmitted"
21294,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.119047619,"it, that, the, and, of"
21295,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.119047619,"of, to, the, in, that"
21296,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.119047619,"a, that, with, to, the"
21297,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.119047619,"closely, related, and, are, to"
21298,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.119047619,"a, of, be, the, that"
21299,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.119047619,"these, the, results, that, be"
21300,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.119047619,"with, the, of, infection, human"
21301,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.119047619,"of, with, are, the, sars-cov-2"
21302,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.119047619,"the, in, to, huanan, market"
21303,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.119047619,"to, have, at, the, is"
21304,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.119047619,"in, the, is, to, at"
21305,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.119047619,"sars-cov-2, and, cov, to, the"
21306,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.119047619,"the, of, to, sars-cov-2, cov"
21307,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.119047619,"sars-cov-2, a, was, in, an"
21308,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.119047619,"the, sars-cov-2, to, a, bat"
21309,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.119047619,"origin, the, that, an, be"
21310,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.119047619,"a, hypothesis, that, the, was"
21311,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.119047619,"of, a, the, was, taken"
21312,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.119047619,"and, the, was, a, in"
21313,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.119047619,"of, the, in, a, pangolin"
21314,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.119047619,"the, hypothesis, of, a, and"
21315,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.119047619,"the, coronavirus, than, to, human"
21316,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.119047619,"the, by, was, a, to"
21317,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.119047619,"the, to, of, and, human"
21318,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.119047619,"a, of, bats, the, china"
21319,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.119047619,"found, are, a, the, of"
21320,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.119047619,"and, sars-cov-2, to, in, viruses"
21321,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.119047619,"the, viruses, and, of, to"
21322,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.119047619,"zoonotic, and, in, the, to"
21323,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.119047619,"the, of, sars-cov-2, in, for"
21324,"insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.119047619,"from, of, as, bats,, and"
21325,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.119047619,"the, were, in, with, a"
21326,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.119047619,"sars-cov-2, a, with, the, for"
21327,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.119047619,"to, the, of, as, spillover"
21328,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.119047619,"human, a, of, the, most"
21329,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.119047619,"of, a, the, to, bat"
21330,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.119047619,"the, bat, to, be, of"
21331,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.119047619,"of, the, that, sars-cov-2, viruses"
21332,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.119047619,"that, the, sars-cov-2, is, viruses"
21333,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.119047619,"the, to, sars-cov-2, was, virus"
21334,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.119047619,"sars-cov-2, genome, to, and, the"
21335,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.119047619,"in, to, the, sars-cov-2, is"
21336,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.119047619,"is, to, the, that, wiv"
21337,"Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.119047619,"is, a, for, and, evolution"
21338,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.119047619,"in, a, of, to, the, that, analysis, is, from, found"
21339,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.119047619,"sequences, were, from, of, and"
21340,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.119047619,"with, and, of, the, in"
21341,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.119047619,"sars-cov-2, the, in, and, of"
21342,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.119047619,"of, in, and, which, the"
21343,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.119047619,"of, sars-cov-2, which, the, in"
21344,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.119047619,"sars-cov-2, has, in, of, found"
21345,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.119047619,"the, is, to, that, sars-cov-2"
21346,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.119047619,"discovered, similar, to, sars-cov-2, the"
21347,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.119047619,"identity, with, the, virus, from"
21348,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.119047619,"the, by, that, not, a"
21349,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.119047619,"a, origin, of, by, the"
21350,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.119047619,"that, the, of, has, been"
21351,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.119047619,"the, of, zoonotic, by, a"
21352,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.119047619,"the, to, has, in, of"
21353,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.119047619,"from, the, has, to, sars-cov-2"
21354,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","bats are also important reservoir species for a great 

range of coronaviruses",0.119047619,"also, a, of, important, for"
21355,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.119047619,"sars-cov-2, from, to, in, an"
21356,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.119047619,"from, the, bat, similarities, and"
21357,"civet cats and raccoon dogs  

are the intermediate hosts","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.119047619,"cats, and, the, intermediate, hosts"
21358,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.119047619,"that, sars-cov-2, a, to, in"
21359,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.119047619,"the, to, that, sars-cov-2, was"
21360,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.119047619,"sars-cov-2, to, could, be, the"
21361,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.119047619,"from, as, intermediate, to, the"
21362,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.119047619,"of, that, the, possibility, a"
21363,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.119047619,"the, to, and, animal, sars-cov-2"
21364,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.119047619,"several, the, sars-cov-2, and, to"
21365,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.119047619,"that, from, in, intermediate, host"
21366,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.119047619,"the, of, that, was, from"
21367,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.119047619,"the, that, in, from, market"
21368,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.119047619,"the, of, from, in, sars-cov-2"
21369,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.119047619,"is, a, of, the, in"
21370,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.119047619,"and, in, bats, of, more"
21371,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.119047619,"bats, are, the, most, likely"
21372,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.119047619,"sars-cov-2, the, of, coronaviruses, including"
21373,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.119047619,"of, the, viruses, bats, reservoirs"
21374,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.119047619,"viruses, the, and, bats, for"
21375,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.119047619,"sars-cov-2, to, bat, as, the"
21376,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.119047619,"the, sars-cov-2, reservoir, likely, and"
21377,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.119047619,"that, the, to, bat, and"
21378,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.119047619,"the, in, that, are, sars-cov-2"
21379,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.119047619,"that, the, sars-cov-2, and, bat"
21380,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.119047619,"and, southern, viruses, in, the"
21381,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.119047619,"to, and, viruses, related, in"
21382,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.119047619,"and, bat, to, the, in"
21383,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.119047619,"the, and, by, a, in"
21384,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.119047619,"the, and, viruses, in, southern"
21385,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.119047619,"in, a, the, of, possible"
21386,Many of these CoVs can infect several animal species as well,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.119047619,"of, can, infect, species, as"
21387,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.119047619,"the, of, closely, related, virus, to, as, is, bat, sars-related"
21388,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.119047619,"a, to, of, sars-cov-2, from"
21389,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.119047619,"known, to, closest, sars-cov-2,, of"
21390,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.119047619,"and, are, closely, related, to"
21391,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.119047619,"the, discovered, similar, to, sars-cov-2"
21392,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.119047619,"that, the, of, to, with"
21393,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.119047619,"of, to, the, than, that"
21394,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.119047619,"that, through, with, to, the"
21395,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.119047619,"from, is, spike, in, the"
21396,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.119047619,"viruses, of, the, have, their"
21397,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.119047619,"is, to, have, at, the"
21398,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.119047619,"the, of, bat, to, sars-related, as, closely, related, virus, is"
21399,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.119047619,"the, known, to, closely, related, most, in, wiv’s, is, sars-cov-2"
21400,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.119047619,"the, sars-cov-2, virus, is, to"
21401,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.119047619,"with, other, coronaviruses,, sars-cov-2, events"
21402,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.119047619,"were, with, that, zoonotic, events"
21403,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.119047619,"a, from, in, that, the, virus, to, of, were, found"
21404,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.119047619,"or, the, infected, by, several, species, of, small, to, as, civets, and, in, other, also"
21405,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.119047619,"the, covid-19, to, and, a"
21406,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.119047619,"the, sars, and, are, to"
21407,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.119047619,"the, known, and, to, in"
21408,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.119047619,"to, the, that, a, spillover"
21409,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.119047619,"to, the, in, zoonotic, and"
21410,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.119047619,"that, are, the, a, and"
21411,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.119047619,"in, this, that, the, and"
21412,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.119047619,"a, the, with, that, to"
21413,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.119047619,"a, for, sars-cov-2, with, the"
21414,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.119047619,"through, that, the, with, to"
21415,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.119047619,"were, to, that, in, and"
21416,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.119047619,"the, to, a, of, and"
21417,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.119047619,"the, of, and, which, in"
21418,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.119047619,"a, and, in, the, to"
21419,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.119047619,"to, natural, the, of, and"
21420,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.119047619,"the, results, of, to, a"
21421,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.119047619,"sars-cov-2, was, in, an, a"
21422,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.119047619,"a, bat, that, the, sars-cov-2"
21423,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.119047619,"that, a, sars-cov-2, the, genomic"
21424,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.119047619,"the, in, that, sars-cov-2, virus"
21425,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.119047619,"a, that, the, virus, bat"
21426,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.119047619,"the, bat, its, sequence, in"
21427,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.119047619,"that, sars-cov-2, the, result, of"
21428,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.119047619,"that, is, to, a, human"
21429,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.119047619,"sars-cov-2, a, that, is, this"
21430,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.119047619,"been, the, of, probably, had"
21431,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.119047619,"that, the, is, previously, used"
21432,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.119047619,"the, genetic, virus, is, that"
21433,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.119047619,"from, is, the, that, not"
21434,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.119047619,"that, of, the, is, likely"
21435,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.119047619,"of, that, the, to, bat"
21436,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.119047619,"that, the, similarity, bat, is"
21437,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.119047619,"is, from, in, the, spike"
21438,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.119047619,"the, that, is, not, from"
21439,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.119047619,"this, the, pangolin, for, sars-cov-2"
21440,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.119047619,"genomic, that, sars-cov-2, through, the"
21441,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.119047619,"a, that, genomic, the, sars-cov-2"
21442,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.119047619,"the, of, it, is, that"
21443,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.119047619,"the, virus, was, that, to"
21444,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.119047619,"the, virus, an, in, to"
21445,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.119047619,"that, the, virus, to, of"
21446,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.119047619,"to, virus, was, the, sars-cov-2"
21447,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.119047619,"virus, that, the, sars-cov-2, in"
21448,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.119047619,"that, sars-cov-2, to, in, an"
21449,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.119047619,"the, with, a, from, sars-cov-2"
21450,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.119047619,"is, coronavirus, from, have, been"
21451,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.119047619,"that, the, was, not, first"
21452,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.119047619,"not, but, that, the, a"
21453,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.119047619,"the, genome, analysis, that, a"
21454,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.119047619,"analysis, that, the, covid-19, of"
21455,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.119047619,"a, bat, of, genome, the"
21456,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.119047619,"genetic, and, sars-cov, bats, of"
21457,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.119047619,"the, in, bats, more, than"
21458,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.119047619,"to, cov, and, the, of"
21459,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.119047619,"the, analysis, that, and, from"
21460,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.119047619,"that, is, from, animal, a"
21461,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.119047619,"from, a, that, is, bat"
21462,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.119047619,"the, bat, or, origin, of"
21463,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.119047619,"the, viruses, of, that, these"
21464,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.119047619,"the, genomic, that, in, and"
21465,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.119047619,"of, the, virus, covid-19, and"
21466,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.119047619,"analysis, that, the, of, covid-19"
21467,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.119047619,"that, bats, the, hosts, genomic"
21468,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.119047619,"humans, and, to, through, be"
21469,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.119047619,"are, to, in, that, be"
21470,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.119047619,"the, in, china, seafood, market"
21471,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.119047619,"that, of, the, market,, which"
21472,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.119047619,"of, the, have, been, in"
21473,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.119047619,"the, analysis, revealed, that, and"
21474,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.119047619,"in, can, be, that, the"
21475,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.119047619,"with, appear, to, the, of"
21476,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.119047619,"has, the, of, to, in"
21477,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.119047619,"bats, a, of, the, china"
21478,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.119047619,"there, is, that, of, species"
21479,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.119047619,"from, in, china, the, bat"
21480,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.119047619,"the, and, is, to, humans"
21481,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.119047619,"and, the, was, bats, in"
21482,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.119047619,"infected, to, as, civets, in, the, or, by, of, several, and, other, small, also, species"
21483,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.119047619,"the, in, and, a, market"
21484,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.119047619,"and, the, was, in, of"
21485,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.119047619,"of, the, viruses, have, their"
21486,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.119047619,"sars-cov-2, domain, receptor, protein, in"
21487,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.119047619,"the, of, sars-cov-2, is, with"
21488,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.119047619,"the, from, in, or, bats"
21489,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.119047619,"and, of, wild, this, the"
21490,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.119047619,"that, of, the, wild, animals"
21491,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.119047619,"a, the, is, most, likely"
21492,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.119047619,"a, the, to, which, covs"
21493,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.119047619,"a, has, that, sars-cov-2, and"
21494,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.119047619,"sars-cov-2, and, bat, showing, identity"
21495,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.119047619,"the, and, of, virus, to"
21496,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.119047619,"that, the, role, of, to, or, have, a, by, other"
21497,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.119047619,"in, an, from, to, sars-cov-2"
21498,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.119047619,"a, that, to, in, sars-cov-2"
21499,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.119047619,"in, from, that, intermediate, host"
21500,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.119047619,"in, an, to, that, sars-cov-2"
21501,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.119047619,"in, show, that, sars-cov-2, a"
21502,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.119047619,"the, of, with, that, is"
21503,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.119047619,"recent, suggest, that, sars-cov-2, studies"
21504,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.119047619,"that, the, of, a, possibility"
21505,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.119047619,"the, that, a, but, not"
21506,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.119047619,"was, to, sars-cov-2, the, genome"
21507,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.119047619,"the, of, that, a, human"
21508,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.119047619,"the, virus, a, that, and"
21509,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.119047619,"the, of, most, a, human"
21510,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.119047619,"the, of, is, likely, that"
21511,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.119047619,"the, a, is, most, likely"
21512,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.119047619,"the, hypothesis, and, a, of"
21513,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.119047619,"in, such, have, to, and"
21514,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.119047619,"that, to, and, are, sars-cov-2"
21515,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.119047619,"genome, bat, ratg13, overall, sars-cov-2"
21516,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.119047619,"bat, ratg13, with, sars-cov-2, than"
21517,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.119047619,"the, that, an, be, origin"
21518,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.119047619,"the, wiv, that, is, to"
21519,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.119047619,"the, of, these, to, emergence"
21520,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.119047619,"the, to, which, was, in"
21521,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.119047619,"the, of, which, in, sars-cov-2"
21522,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.119047619,"sars-cov-2, to, in, the, which"
21523,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.119047619,"the, and, to, sars-, cov-2"
21524,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.119047619,"of, natural, and, to, the"
21525,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.119047619,"on, the, comparative, that, sars-cov-2"
21526,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.119047619,"genomic, that, the, bats, hosts"
21527,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.119047619,"recent, studies, suggest, that, sars-cov-2"
21528,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.119047619,"t, that, bats, are, the"
21529,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.119047619,"a, at, the, of, in, found, virus, that, were, is"
21530,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.119047619,"the, of, were, that, virus, from, a, found, in, to"
21531,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.119047619,"the, sars-cov-2, to, bats, is"
21532,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.119047619,"the, to, sars-cov-2, a, bat"
21533,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.119047619,"the, most, likely, are, bats"
21534,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.119047619,"a, virus, that, the, bat"
21535,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.119047619,"the, to, covs, which, a"
21536,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.119047619,"the, probable, of, sars-cov-2, at"
21537,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.119047619,"the, a, in, wuhan,, china"
21538,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.119047619,"the, of, origin, by, a"
21539,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.119047619,"the, of, genome, a, bat"
21540,"bats are also important reservoir species for a great 

range of coronaviruses","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.119047619,"also, important, for, a, of"
21541,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.119047619,"may, the, hosts, of, and"
21542,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.119047619,"sars-cov-2, may, a, virus, that"
21543,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.119047619,"sars-cov-2, the, have, been, to"
21544,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.119047619,"that, the, of, viruses, sars-cov-2"
21545,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.119047619,"show, that, sars-cov-2, a, in"
21546,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.119047619,"of, that, the, sarbecovirus, naturally"
21547,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.119047619,"the, of, is, that, sars-cov-2"
21548,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.119047619,"is, that, sars-cov-2, the, of"
21549,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.119047619,"results, that, the, be, these"
21550,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.119047619,"bats, the, for, viruses, and"
21551,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.119047619,"that, are, to, be, in"
21552,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.119047619,"bat, with, sars-cov-2, than, ratg13"
21553,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.119047619,"that, of, sars-cov-2, been, coronavirus"
21554,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.119047619,"the, sars-cov-2, likely, that, and"
21555,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.119047619,"the, more, likely, that, and"
21556,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.119047619,"from, the, has, coronavirus, sars-cov-2"
21557,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.119047619,"viruses, to, the, that, and"
21558,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.119047619,"sars-cov-2, and, to, cov, the"
21559,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same",0.119047619,"the, bat, cov, and, same"
21560,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.119047619,"sars-cov-2, to, which, the, in"
21561,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.119047619,"of, the, bat, origin, or"
21562,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.119047619,"the, that, are, sars-cov-2, in"
21563,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.119047619,"the, more, than, in, bats"
21564,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.119047619,"is, the, that, similarity, and"
21565,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.119047619,"the, that, bat, and, similarity"
21566,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.119047619,"and, that, the, sars, bat"
21567,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.119047619,"the, that, sars-cov-2, bat, and"
21568,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.119047619,"the, similarity, bat, is, that"
21569,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.119047619,"the, that, sars-cov-2, and, similarity"
21570,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.119047619,"is, that, the, viruses, sars-cov-2"
21571,hese close genetic relations suggest that they all have their ecological origin in bat populations,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.119047619,"they, all, have, origin, bat"
21572,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.119047619,"from, the, bat, and, similarities"
21573,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.119047619,"bat, and, in, the, of"
21574,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.119047619,"the, bat, from, in, china"
21575,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.119047619,"a, the, to, that, and"
21576,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.119047619,"cov, that, origin, other, and"
21577,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.119047619,"are, a, of, the, found"
21578,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.119047619,"the, of, to, and, cov"
21579,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.119047619,"a, of, to, results, the"
21580,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.119047619,"the, of, to, and, sars-cov-2"
21581,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.119047619,"the, of, and, sars-cov-2, is"
21582,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.119047619,"is, with, sars-cov-2, the, of"
21583,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.119047619,"that, the, sars-cov-2, and, for"
21584,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.119047619,"in, the, of, that, sars-cov-2"
21585,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.119047619,"a, originated, from, and, the"
21586,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.119047619,"the, and, are, of, that"
21587,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.119047619,"a, that, bats, and, the"
21588,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.119047619,"are, a, and, the, that"
21589,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.119047619,"the, of, that, are, a"
21590,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.119047619,"the, of, that, a, for"
21591,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.119047619,"the, reservoir, and, number, of"
21592,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.119047619,"the, sars-cov-2, and, for, is"
21593,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.119047619,"are, in, to, the, and"
21594,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.119047619,"to, and, are, the, sars-cov-2"
21595,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.119047619,"the, of, that, in, this"
21596,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.119047619,"phylogenetic, to, the, of, sars-cov-2"
21597,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.119047619,"that, the, similarity, sars-cov-2, and"
21598,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.119047619,"the, to, closest, of, less"
21599,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.119047619,"the, and, of, bat, that"
21600,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.119047619,"the, an, that, of, and"
21601,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.119047619,"the, that, of, and, it"
21602,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.119047619,"the, that, can, be, in"
21603,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.119047619,"the, of, this, that, in"
21604,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.119047619,"the, and, it, an, of"
21605,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.119047619,"that, the, was, to, sars-cov-2"
21606,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.119047619,"the, of, from, that, was"
21607,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.119047619,"that, sars-cov-2, to, the, of"
21608,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.119047619,"the, to, sars-cov-2,, rbd, of"
21609,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.119047619,"is, to, at, the, in"
21610,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.119047619,"pangolin, sars-cov-2, the, this, for"
21611,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.119047619,"of, together, with, revealed, and"
21612,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.119047619,"the, key, residues, of, to"
21613,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.119047619,"the, bat, and, sars-cov-2, might"
21614,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.119047619,"the, of, sars-cov-2, be, and"
21615,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.119047619,"the, and, suggesting, sars-cov-2, an"
21616,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.119047619,"and, suggesting, a, between, the"
21617,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.119047619,"that, the, for, a, of"
21618,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.119047619,"sars-cov-2, covid-19, for, human, a, would, or, that, in, the"
21619,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.119047619,"sars-cov-2, be, a, animal, the"
21620,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.119047619,"that, sars-cov-2, a, animal, or"
21621,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.119047619,"the, reservoir, number, of, and"
21622,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.119047619,"it, the, and, an, of"
21623,"The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.119047619,"that, events, were, with, zoonotic"
21624,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.119047619,"that, the, of, in, to"
21625,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.119047619,"sars-cov-2, to, the, that, in"
21626,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.119047619,"to, the, of, be, bat"
21627,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.119047619,"closest, known, to, sars-cov-2,, of"
21628,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.119047619,"sequence, the, in, its, bat"
21629,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.119047619,"the, closest, of, less, to"
21630,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.119047619,"the, rbd, of, to, sars-cov-2,"
21631,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.119047619,"and, viruses, related, to, in"
21632,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.119047619,"evidence, that, the, as, of"
21633,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.119047619,"that, the, may, of, to"
21634,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.119047619,"to, the, key, residues, of"
21635,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.119047619,"and, the, bat, ratg13, of"
21636,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.119047619,"to, sars-cov-2, and, the, pangolin"
21637,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.119047619,"of, the, and, bat, identity"
21638,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.119047619,"showing, identity, bat, and, sars-cov-2"
21639,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.118881119,"in, than, the, known, sars, of, that, at, was, to, different, by, coronavirus, is, closely, related, and"
21640,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.118881119,"the, that, was, known, to, closely, related, sars, coronavirus, in, is, different, by, than, of, and, at"
21641,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.118811881,"an, a, from, animal, in, chinese, the, live, animals,, of, and, including"
21642,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.118811881,"in, the, of, found, that, virus, was, similar, to, indicated, closely, related"
21643,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.118811881,"from, the, was, to, a, with, and, by, of, sample, taken, at"
21644,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.118811881,"found, in, the, of, indicated, that, was, closely, related, to, similar, virus"
21645,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.118811881,"the, sample, by, was, taken, from, a, at, and, to, of, with"
21646,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.118811881,"in, chinese, the, live, animals,, including, from, an, animal, and, a, of"
21647,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.118644068,"that, the, in, bats, and, from, a"
21648,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.118644068,"of, southeast, asia, and, a, in, the"
21649,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.118644068,"coronaviruses, sars-cov, and, a, to, human, pangolin"
21650,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.118644068,"of, for, were, infected, with, coronavirus, that"
21651,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.118644068,"have, the, of, human, to, and, which"
21652,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.118644068,"the, and, of, bat, coronaviruses, to, human"
21653,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.118644068,"the, of, coronaviruses, and, which, in, sars-cov-2"
21654,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.118644068,"genetic, that, the, virus, in, from, a"
21655,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.118644068,"virus, from, in, is, sars-cov-2, the, sequence"
21656,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.118644068,"the, and, to, of, bat, human, coronaviruses"
21657,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.118644068,"that, are, the, of, all, and, viruses"
21658,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.118644068,"of, with, to, and, the, in, known"
21659,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.118644068,"sars-cov-2, of, the, and, with, to, in"
21660,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.118644068,"bats, of, a, that, in, as, human"
21661,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.118644068,"the, of, with, that, and, is, to"
21662,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.118644068,"the, of, and, are, to, is, that"
21663,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.118644068,"that, in, and, the, virus, for, of"
21664,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.118644068,"the, of, is, and, with, that, to"
21665,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.118644068,"the, was, to, that, in, with, animals"
21666,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.118644068,"to, that, has, been, contact, with, people"
21667,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.118644068,"that, of, from, to, a, sars-cov-2, the"
21668,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.118644068,"a, from, at, that, the, to, of"
21669,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.118644068,"the, a, to, that, bat, are, of"
21670,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.118644068,"the, origin, of, sars-cov-2, a, from, and"
21671,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.118644068,"sars-cov-2, be, of, the, and, to, infection"
21672,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.118644068,"a, in, the, sars-cov-2, from, animal, but"
21673,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.118644068,"that, of, sars-cov-2, samples, from, the, animals"
21674,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.118644068,"the, to, have, that, in, of, animals"
21675,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.118644068,"in, sense, that, sars-cov-2, from, research, laboratory"
21676,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.118644068,"the, as, a, that, from, to, humans"
21677,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.118644068,"is, we, sars-cov-2, and, to, the, that"
21678,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.118644068,"in, a, of, and, that, the, with"
21679,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.118644068,"the, has, of, that, from, to, and"
21680,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.118644068,"the, sars-cov-2, and, to, be, a, is"
21681,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.118644068,"the, as, a, that, from, to, and"
21682,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.118644068,"a, of, for, to, with, coronavirus, that"
21683,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.118644068,"was, by, and, which, to, sars-cov-2, the"
21684,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.118644068,"to, from, a, in, bats, the, and"
21685,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.118644068,"a, and, that, the, from, in, bats"
21686,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.118644068,"that, from, a, the, virus, genetic, in"
21687,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.118644068,"in, the, virus, to, that, and, a"
21688,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.118644068,"at, the, and, in, bats, from, to"
21689,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.118644068,"sequencing, of, the, covid-19, virus, in, and"
21690,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.118644068,"and, in, to, the, of, has, is"
21691,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.118644068,"to, on, the, and, or, be, for"
21692,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.118644068,"sars-cov-2, is, bat, be, to, that, bats"
21693,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.118644068,"to, the, severe, acute, respiratory, bats, that"
21694,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.118644068,"induced, pneumonia, with, the, was, in, of"
21695,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.118644068,"with, the, of, were, as, a, it"
21696,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.118644068,"viruses, the, that, bats, could, be, possible"
21697,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.118644068,"the, is, used, by, also, a, that"
21698,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.118644068,"he, bat, as, genetic, similarity, sars-cov-2, the"
21699,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.118644068,"and, of, between, sars-cov-2, is, an, to"
21700,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.118644068,"was, the, with, induced, pneumonia, in, of"
21701,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.118644068,"in, of, the, covid-19, virus, sequencing, and"
21702,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.118644068,"human, sars-cov, and, to, pangolin, coronaviruses, a"
21703,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.118644068,"to, natural, the, of, sars-, and, be"
21704,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.118644068,"the, of, sequence, that, was, related, to"
21705,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.118644068,"a, of, virus, with, and, the, sars-cov-2"
21706,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.118644068,"that, the, s, protein, of, pangolin, intermediate"
21707,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.118644068,"samples, from, the, of, that, sars-cov-2, animals"
21708,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.118644068,"that, sars-cov-2, is, to, bat, bats, be"
21709,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.118644068,"bats, species, to, as, sars-cov-2, bat, and"
21710,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.118644068,"the, sars-cov-2, of, a, (zhou, et, al.,"
21711,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.118644068,"sars-cov-2, from, a, the, south, has, with"
21712,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.118644068,"the, covid-19, wuhan, december, 2019, huanan, seafood"
21713,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.118644068,"the, of, sars-cov-2, a, (zhou, et, al.,"
21714,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.118644068,"a, origin, of, the, from, sars-cov-2, and"
21715,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.118644068,"the, and, sars-cov-2, of, sarbecovirus, ratg13, as"
21716,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.118644068,"and, from, r., the, of, natural, sars-cov-2"
21717,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.118644068,"the, sequence, of, that, was, to, related"
21718,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.118644068,"that, the, of, in, closely, but, to"
21719,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.118644068,"to, have, the, of, and, which, human"
21720,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.118644068,"of, the, a, high, these, species, as"
21721,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.118644068,"it, the, with, were, as, a, of"
21722,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.118644068,"the, of, for, it, with, and, a"
21723,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.118644068,"it, a, with, two, and, the, genome"
21724,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.118644068,"with, the, of, a, for, it, and"
21725,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.118644068,"within, this, of, and, a, in, the"
21726,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.118644068,"virus, in, is, with, sars-cov-2, the, of"
21727,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.118644068,"to, and, of, it, is, that, in"
21728,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.118644068,"a, study, that, the, to, in, sars-cov-2"
21729,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.118644068,"the, in, of, an, to, that, sars-cov-2"
21730,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.118644068,"that, study, suggests, sars-cov-2, in, an, with"
21731,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.118644068,"the, sars-cov-2, and, which, of, in, coronaviruses"
21732,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.118644068,"several, of, and, the, to, from, species"
21733,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.118644068,"from, in, the, to, of, were, bats"
21734,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.118644068,"the, in, bats, and, to, from, at"
21735,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.118644068,"in, humans, that, the, be, and, sars-cov-2"
21736,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.118644068,"sars-cov-2, and, to, the, between, that, in"
21737,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.118644068,"on, in, suggest, the, based, between, and"
21738,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.118644068,"study, that, to, a, in, sars-cov-2, the"
21739,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.118644068,"the, study, that, in, a, and, to"
21740,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.118644068,"a, study, was, in, that, the, to"
21741,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.118644068,"the, and, a, in, to, that, common"
21742,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.118644068,"some, to, sars-cov-2, the, for, is, of"
21743,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.118644068,"the, also, of, sars-cov-2, is, it, for"
21744,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.118644068,"to, the, of, and, may, for, sars-cov-2"
21745,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.118644068,"and, the, from, bats, to, a, in"
21746,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.118644068,"a, from, the, south, has, with, sars-cov-2"
21747,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.118644068,"virus, from, is, at, sars-cov-2, the, of"
21748,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.118644068,"the, sars-cov-2, to, a, of, is, in"
21749,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.118644068,"sars-cov-2, and, bat, species, as, to, bats"
21750,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.118644068,"a, of, and, the, in, asia, southeast"
21751,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.118644068,"in, the, of, and, this, within, a"
21752,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.118644068,"in, by, a, and, are, similar, the"
21753,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.118644068,"of, and, the, in, viruses, between, bat"
21754,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.118644068,"in, the, of, that, closely, to, but"
21755,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.118644068,"he, bat, the, as, sars-cov-2, genetic, similarity"
21756,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.118644068,"the, and, sars-cov-2, which, was, to, by"
21757,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.118644068,"with, the, a, it, genome, two, and"
21758,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.118644068,"and, similar, are, by, a, in, the"
21759,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.118644068,"are, the, of, is, and, that, to"
21760,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.118644068,"that, and, be, sars-cov-2, humans, the, in"
21761,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.118644068,"covid-19, the, huanan, seafood, wuhan, december, 2019"
21762,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.118644068,"2005,, the, of, a, in, to, that, sars, civets, as, intermediate, and, were, virus"
21763,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.118644068,"in, 2005,, the, of, civets, as, intermediate, sars, a, that, virus, were, to, and"
21764,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.118644068,"with, the, known, and, to, in, of"
21765,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.118644068,"the, between, and, to, a, of, is"
21766,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.118644068,"to, in, bats, rhinolophus, and, that, china"
21767,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.118644068,"of, natural, the, and, viruses, to, in"
21768,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.118644068,"to, the, evidence, of, sars-cov-2, natural, is"
21769,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.118644068,"the, of, sars-cov-2, to, is, for, some"
21770,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.118644068,"to, this, that, sars-cov-2, similarity, the, of"
21771,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.118644068,"that, of, to, an, in, sars-cov-2, the"
21772,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.118644068,"was, in, that, the, virus, to, of"
21773,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.118644068,"the, rbd, also, in, to, that, of"
21774,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.118644068,"a, study, that, the, to, and, in"
21775,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.118644068,"of, a, that, the, to, and, sars"
21776,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.118644068,"the, of, a, high, species, as, these"
21777,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.118644068,"that, to, severe, acute, respiratory, bats, the"
21778,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.118644068,"that, to, in, rhinolophus, bats, and, china"
21779,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.118644068,"a, of, the, outbreak, in, wuhan,, china"
21780,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.118644068,"the, viruses, and, are, all, of, that"
21781,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.118644068,"the, of, evidence, indicates, that, in, for"
21782,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.118644068,"in, the, was, that, animals, to, with"
21783,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.118644068,"that, people, contact, with, has, been, to"
21784,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.118644068,"in, the, of, that, animals, have, to"
21785,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.118644068,"of, the, has, been, that, have, to"
21786,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.118644068,"even, though, the, that, with, of, it"
21787,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.118644068,"of, and, viruses, bat, between, in, the"
21788,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.118644068,"the, of, and, pangolins, have, origin, sars-cov-2"
21789,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.118644068,"is, sars-cov-2, from, the, virus, sequence, in"
21790,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.118644068,"in, the, of, virus, is, sars-cov-2, with"
21791,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.118644068,"is, sars-cov-2, the, of, virus, at, from"
21792,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.118644068,"from, species, of, to, and, the, several"
21793,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.118644068,"the, that, a, as, to, from, humans"
21794,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.118644068,"the, has, to, that, of, and, from"
21795,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.118644068,"to, a, that, from, and, the, as"
21796,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.118644068,"the, of, that, likely, to, a, bat"
21797,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.118644068,"the, to, have, that, has, been, of"
21798,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.118644068,"to, that, has, the, virus, origin, of"
21799,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.118644068,"the, of, sars-cov-2, it, is, also, for"
21800,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.118644068,"even, though, the, it, that, with, of"
21801,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.118644068,"is, the, with, sars-cov-2, that, are, for"
21802,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.118644068,"also, that, with, the, of, as, an"
21803,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.118644068,"in, to, is, of, the, has, and"
21804,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.118644068,"the, of, sars-cov-2, to, is, natural, evidence"
21805,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.118644068,"a, that, the, also, is, used, by"
21806,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.118644068,"and, sars-, to, the, be, natural, of"
21807,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.118644068,"a, at, to, that, the, of, from"
21808,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.118644068,"in, from, of, bats, were, to, the"
21809,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.118644068,"a, study, that, the, was, to, in"
21810,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.118644068,"the, in, of, to, that, was, virus"
21811,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.118644068,"found, that, genome, to, a, the, of"
21812,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.118644068,"the, of, and, bat, that, a, to"
21813,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.118644068,"the, of, that, a, sars, and, to"
21814,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.118644068,"the, and, a, to, that, bat, of"
21815,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.118644068,"the, in, of, a, outbreak, wuhan,, china"
21816,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.118644068,"is, between, and, of, sars-cov-2, to, an"
21817,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.118644068,"to, and, of, is, viruses, ratg13, in"
21818,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.118644068,"study, suggests, that, an, in, with, sars-cov-2"
21819,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.118644068,"a, sars-cov-2, and, with, the, of, virus"
21820,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.118644068,"and, have, the, are, 2, sars-cov-2, with"
21821,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.118644068,"the, of, that, viruses, in, a, and"
21822,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.118644068,"be, the, possible, viruses, that, bats, could"
21823,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.118644068,"the, that, are, with, sars-cov-2, is, for"
21824,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.118644068,"that, the, sars-cov-2, and, is, we, to"
21825,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.118644068,"that, and, sars-cov-2, to, the, between, in"
21826,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.118644068,"the, of, sars-cov-2, as, sarbecovirus, and, ratg13"
21827,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.118644068,"2, have, with, and, are, the, sars-cov-2"
21828,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.118644068,"the, of, sars-cov-2, to, may, for, and"
21829,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.118644068,"of, the, sars-cov-2, have, pangolins, origin, and"
21830,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.118644068,"to, that, sars-cov-2, the, bats, origin, of"
21831,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.118644068,"suggest, and, based, on, the, between, in"
21832,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.118644068,"a, genome, that, the, to, of, found"
21833,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.118644068,"the, a, of, that, likely, to, bat"
21834,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.118644068,"with, the, and, to, sars-cov-2, is, of"
21835,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.118644068,"of, the, we, that, sars-cov-2, and, in"
21836,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.118644068,"for, the, of, virus, and, in, that"
21837,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.118644068,"similarity, to, sars-cov-2, the, this, that, of"
21838,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.118644068,"of, the, has, that, to, origin, virus"
21839,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.118644068,"to, that, the, of, bats, origin, sars-cov-2"
21840,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.118644068,"evidence, indicates, that, the, of, in, for"
21841,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.118644068,"in, the, but, from, animal, a, sars-cov-2"
21842,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.118644068,"that, sense, sars-cov-2, from, in, laboratory, research"
21843,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.118644068,"of, that, for, were, infected, with, coronavirus"
21844,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.118644068,"for, a, of, to, with, that, coronavirus"
21845,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.118644068,"in, of, that, as, a, human, bats"
21846,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.118644068,"the, natural, of, sars-cov-2, from, and, r."
21847,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.118644068,"the, rbd, in, to, bat, of, sars-cov-2,"
21848,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.118644068,"a, are, to, bat, that, the, of"
21849,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.118644068,"a, that, the, to, common, and, in"
21850,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.118644068,"the, in, of, rbd, to, that, also"
21851,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.118644068,"the, bat, to, sars-cov-2,, in, rbd, of"
21852,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.118644068,"in, of, it, is, to, that, and"
21853,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.118644068,"and, of, ratg13, in, is, viruses, to"
21854,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.118644068,"the, s, protein, of, pangolin, that, intermediate"
21855,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.118644068,"the, that, also, with, of, as, an"
21856,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.118644068,"the, to, be, sars-cov-2, infection, and, of"
21857,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.118644068,"of, viruses, in, natural, and, to, the"
21858,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.118518519,"the, of, a, sars-related, viruses, in, to, that, bats, with, as, and, virus, similar, also, for"
21859,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.118518519,"and, the, of, also, to, similar, sars-related, viruses, as, a, bats, with, that, in, for, virus"
21860,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.118421053,"sars-cov-2, be, of, the, and, site, to, in, genetic"
21861,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.118421053,"as, the, of, and, are, viruses, they, other, more"
21862,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.118421053,"the, that, of, are, and, genomic, lineage, in, at"
21863,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.118421053,"and, with, at, the, huanan, market, in, of, a"
21864,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.118421053,"the, huanan, market, is, in, of, and, with, a"
21865,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.118421053,"are, the, they, as, of, and, more, viruses, other"
21866,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.118421053,"that, the, near, to, with, high, in, of, and"
21867,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.118421053,"for, the, raccoon, and, intermediate, host, palm, or, to"
21868,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.118421053,"sars-cov, reservoir, intermediate, and, raccoon, to, for, the, may"
21869,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.118421053,"in, the, of, as, was, a, that, infected, were"
21870,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.118421053,"to, sars-cov-2, from, a, in, bats, and, that, coronaviruses"
21871,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.118421053,"for, from, environmental, samples, the, market, in, of, positive"
21872,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.118421053,"sars-cov-2, a, and, coronaviruses, from, to, that, in, bats"
21873,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.118421053,"coronaviruses, in, bats, to, that, of, sars-cov-2, and, sequences"
21874,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.118421053,"in, the, a, to, and, more, closely, related, than"
21875,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.118421053,"in, a, of, being, for, to, with, suggesting, that"
21876,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.118421053,"to, the, and, palm, or, raccoon, intermediate, host, for"
21877,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.118421053,"was, that, the, infected, in, were, as, a, of"
21878,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.118421053,"a, closely, related, to, in, more, than, the, and"
21879,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.118421053,"with, a, and, of, at, the, huanan, market, in"
21880,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.118421053,"positive, environmental, samples, from, the, market, of, in, for"
21881,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.118421053,"is, with, a, and, of, the, huanan, market, in"
21882,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.118421053,"of, the, lineage, that, genomic, and, are, at, in"
21883,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.118421053,"bats, are, of, and, a, large, diversity, to, as"
21884,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.118421053,"to, the, and, reservoir, raccoon, may, intermediate, for, sars-cov"
21885,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.118421053,"to, sars-cov-2, of, sequences, in, bats, and, that, coronaviruses"
21886,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.118421053,"that, the, of, in, to, with, high, near, and"
21887,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.118421053,"a, of, in, that, for, with, being, suggesting, to"
21888,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.118421053,"a, to, bats, large, diversity, of, and, are, as"
21889,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.118421053,"the, site, sars-cov-2, and, to, be, of, genetic, in"
21890,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.11827957,"with, the, huanan, and, of, a, in, this, is, at, market"
21891,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.11827957,"a, the, of, in, raccoon, we, found, virus, that, were, is"
21892,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.11827957,"in, a, of, the, we, virus, that, is, raccoon, were, found"
21893,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.11827957,"or, bats, which, the, could, be, of, to, as, and, sars-cov"
21894,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.11827957,"and, also, a, of, in, which, is, the, for, viruses, to"
21895,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.11827957,"of, virus, that, similar, to, the, bat, and, for, was, named"
21896,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.11827957,"this, is, with, a, and, of, at, the, huanan, market, in"
21897,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.11827957,"the, was, for, to, virus, that, similar, named, bat, and, of"
21898,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.11827957,"bats, as, the, to, be, which, sars-cov, or, of, could, and"
21899,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.11827957,"in, these, are, and, sars-cov-2, with, this, that, the, origin, than"
21900,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.11827957,"and, the, of, also, to, viruses, a, in, for, which, is"
21901,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.11827957,"that, are, than, the, sars-cov-2, these, with, in, this, origin, and"
21902,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.118110236,"in, the, of, a, to, cave, with, coronaviruses, could, and, that, recombination, events, from, it"
21903,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.118110236,"to, could, from, a, recombination, of, in, the, cave, and, it, that, events, with, coronaviruses"
21904,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.117647059,"a, of, viruses, in"
21905,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.117647059,"bats, reservoir, a, of"
21906,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.117647059,"and, the, from, bats, a, in"
21907,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.117647059,"and, are, to, other, viral, a"
21908,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.117647059,"and, viruses, are, bat, a, in"
21909,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.117647059,"to, and, viruses, related, in, bat"
21910,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.117647059,"natural, virus, into, humans, the, pandemic"
21911,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.117647059,"of, coronaviruses, a, in, viruses, are"
21912,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.117647059,"a, in, coronaviruses, are, of, but"
21913,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.117647059,"to, are, bats, the"
21914,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.117647059,"have, in, to, and"
21915,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.117647059,"sars-cov-2, to, of, and"
21916,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.117647059,"and, bats, of, to"
21917,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.117647059,"of, to, sars-cov-2, in"
21918,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.117647059,"species, and, infected, from"
21919,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.117647059,"the, very, to, viruses,, and, sars"
21920,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.117647059,"the, many, are, and, sequences, within"
21921,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.117647059,"the, genetic, sars-, cov-2"
21922,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.117647059,"the, sars-cov, and, many"
21923,COVID-19 is a zoonotic virus,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.117647059,"is, virus"
21924,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.117647059,"in, to, sars-cov-2, virus"
21925,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.117647059,"in, more, sars-cov-2, than"
21926,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.117647059,"the, in, bats, of"
21927,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.117647059,"of, the, in, china"
21928,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.117647059,"the, virus, with, bat, and, to"
21929,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.117647059,"and, the, virus, to, of, bat"
21930,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.117647059,"to, of, which, have, from, with"
21931,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.117647059,"the, with, of, virus, and, to"
21932,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.117647059,"of, it, is, to, the, was"
21933,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.117647059,"origin, by, a, that"
21934,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.117647059,"the, of, genetic, sequences, from, that"
21935,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.117647059,"that, sars-cov-2, sequences, to, the, of"
21936,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.117647059,"a, that, the, sars-cov-2, ace2, 2), and, for, to, which"
21937,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.117647059,"the, of, sars-cov-2, to, human, bat"
21938,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.117647059,"the, of, sars-cov-2, a, between, and"
21939,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.117647059,"the, of, bat, in, recombination, a, to, genetic"
21940,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.117647059,"is, in, the, s2, of, spike"
21941,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.117647059,"a, virus, the, was, by, from"
21942,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.117647059,"and, are, to, a, viral, other"
21943,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.117647059,"is, that, sars-cov-2, and"
21944,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.117647059,"is, that, many, with, and, within"
21945,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.117647059,"genetic, that, is, virus"
21946,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.117647059,"is, with, and, sars-cov-2"
21947,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.117647059,"of, and, viruses, are, bat, the"
21948,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.117647059,"to, and, of, that, viruses, bat"
21949,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.117647059,"that, several, the, natural"
21950,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.117647059,"that, sars-cov-2, to, with"
21951,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.117647059,"the, that, bat, as"
21952,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.117647059,"the, shares, to, identity"
21953,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.117647059,"of, that, the, is, bat, a"
21954,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.117647059,"of, has, and, bat"
21955,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.117647059,"are, and, the, a"
21956,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.117647059,"and, sars-cov-2, bat, cov, ratg13, that, the, same"
21957,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.117647059,"the, to, sars-cov-2, that, cov, virus"
21958,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.117647059,"sequences, of, and, which, were, in"
21959,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.117647059,"of, between, patients, and"
21960,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.117647059,"of, sars-cov-2, with, and"
21961,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.117647059,"the, to, of, known"
21962,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.117647059,"covs, to, in, and"
21963,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.117647059,"the, of, can, and, be, that, greatly, to"
21964,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.117647059,"the, of, that, to, animal, origin"
21965,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.117647059,"the, sars-cov-2, to, humans, of, be"
21966,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.117647059,"the, that, its, in"
21967,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.117647059,"viruses, of, the, have, been, and"
21968,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.117647059,"the, of, can, be, to, that, greatly, and"
21969,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.117647059,"in, with, the, and, to, that, is, of, are, as"
21970,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.117647059,"the, virus, a, to, that, and"
21971,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.117647059,"the, virus, to, human"
21972,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.117647059,"the, to, human, is, a, that"
21973,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.117647059,"that, a, virus, to, and, the"
21974,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.117647059,"of, the, as, in"
21975,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.117647059,"the, origin, of, to, that, animal"
21976,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.117647059,"origin, of, the, this, that, zoonotic, in, were"
21977,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.117647059,"this, in, the, of, that, to"
21978,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.117647059,"is, to, in, the, that, it"
21979,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.117647059,"the, that, in, animal, this, covid-19"
21980,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.117647059,"in, were, to, that, the, of, is, likely"
21981,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.117647059,"and, sars-cov-2, to, of"
21982,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.117647059,"the, to, be, of, transmission, and"
21983,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.117647059,"is, a, sars-cov-2, to"
21984,"bats are also important reservoir species for a great 

range of coronaviruses","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.117647059,"bats, are, species, of"
21985,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.117647059,"of, and, are, by, species, the"
21986,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.117647059,"the, and, are, of"
21987,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.117647059,"the, and, of, natural"
21988,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.117647059,"natural, the, of, and"
21989,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.117647059,"the, natural, and, of"
21990,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.117647059,"the, species, to, as, intermediate, and"
21991,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.117647059,"intermediate, species, and, the, masked, palm"
21992,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.117647059,"the, sequence, with, sars-cov-2"
21993,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.117647059,"the, of, sequence, identity"
21994,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.117647059,"with, the, of, covid-19"
21995,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.117647059,"the, covid-19, outbreak, of"
21996,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.117647059,"the, was, from, at, to, wuhan"
21997,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.117647059,"the, was, to, identical"
21998,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",Bats are likely reservoir hosts for SARS-CoV-2,0.117647059,"sars-cov-2, likely"
21999,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",zoonotic origins of SARS-CoV-2 by natural evolution,0.117647059,"sars-cov-2, zoonotic"
22000,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.117647059,"sars-cov-2, the, sequence, with"
22001,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.117647059,"the, sequence, sars-cov-2, is"
22002,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.117647059,"the, sars-cov-2, homology, with"
22003,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.117647059,"sars-cov-2, a, origin, zoonotic"
22004,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.117647059,"a, zoonotic, origin, the"
22005,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.117647059,"the, respiratory, humans,, coronaviruses, to, and"
22006,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.117647059,"in, to, the, other"
22007,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.117647059,"to, the, and, was"
22008,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.117647059,"the, in, animals, humans"
22009,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.117647059,"the, sars-cov-2, of, is, in, bat"
22010,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.117647059,"in, that, the, lineage"
22011,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.117647059,"sars-cov-2, the, in, of"
22012,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.117647059,"of, sars-cov-2, the, in"
22013,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.117647059,"sars-cov-2, bat, the, of"
22014,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.117647059,"that, sars-cov-2, and, is"
22015,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.117647059,"to, sars-cov-2, the, that, is, of"
22016,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.117647059,"the, that, with, of, sars-cov-2, is"
22017,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.117647059,"to, that, the, of, and, sars-cov-2"
22018,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.117647059,"the, of, that, bats"
22019,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.117647059,"that, natural, are, the"
22020,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.117647059,"that, the, sars, of"
22021,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.117647059,"the, are, that, of"
22022,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.117647059,"the, of, showed, bats"
22023,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","civet cats and raccoon dogs  

are the intermediate hosts",0.117647059,"the, intermediate"
22024,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.117647059,"coronaviruses, the, humans,, to, and, respiratory"
22025,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.117647059,"that, are, the, for, to, a"
22026,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.117647059,"sars-cov-2, and, can, be, to, bats"
22027,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.117647059,"bats, are, to, of, sars-cov-2, and"
22028,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.117647059,"bats, be, the, sars-cov-2"
22029,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","with the first case being linked to  

a seafood market",0.117647059,"a, with, to, the"
22030,"In the 

case of MERS, dromedaries were the principal host.","with the first case being linked to  

a seafood market",0.117647059,"the, case"
22031,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.117647059,"the, of, be, to, humans, sars-cov-2"
22032,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.117647059,"that, a, origin, by"
22033,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.117647059,"a, that, the, by"
22034,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.117647059,"the, that, in, and"
22035,"All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.117647059,"the, that, in, a"
22036,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.117647059,"a, zoonotic, that, and"
22037,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.117647059,"and, the, a, in"
22038,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.117647059,"the, that, (i.e.,, zoonotic"
22039,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.117647059,"the, that, which, and"
22040,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.117647059,"the, by, a, that"
22041,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.117647059,"it, been, that, the"
22042,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.117647059,"the, was, by, a"
22043,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.117647059,"it, was, by, a, other, the"
22044,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.117647059,"by, the, not, other"
22045,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.117647059,"in, from, a, an, animal, to"
22046,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.117647059,"studies, to, bat, and, a, high"
22047,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.117647059,"studies, have, are, reservoir, a, and"
22048,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.117647059,"of, the, evidence, natural"
22049,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.117647059,"the, to, of, as"
22050,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.117647059,"the, of, to, from"
22051,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.117647059,"the, of, that, from, to, as"
22052,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.117647059,"that, the, of, as, a, to"
22053,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.117647059,"natural, of, the, a, to, that"
22054,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.117647059,"the, that, are, natural"
22055,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.117647059,"that, have, and, are, the, sars-cov-2"
22056,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.117647059,"that, are, the, sars-cov-2"
22057,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.117647059,"have, that, the, and, from, at"
22058,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.117647059,"they, that, the, of"
22059,Bats are likely reservoir hosts for SARS-CoV-2,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.117647059,"likely, sars-cov-2"
22060,zoonotic origins of SARS-CoV-2 by natural evolution,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.117647059,"zoonotic, sars-cov-2"
22061,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.117647059,"a, of, to, the, are, that, this, from"
22062,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.117647059,"a, of, the, bat, viruses, that"
22063,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.117647059,"from, to, this, the, of, that, sars-cov-2, a"
22064,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.117647059,"the, of, that, were, in, this, zoonotic, origin"
22065,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.117647059,"the, into, animal, in, market, and"
22066,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.117647059,"the, that, in, lineage"
22067,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.117647059,"that, the, in, closely, a, to"
22068,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.117647059,"we, that, in, the"
22069,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.117647059,"of, the, is, a"
22070,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.117647059,"and, in, at, the"
22071,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.117647059,"is, the, with, and"
22072,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.117647059,"was, from, a, by, the, virus"
22073,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.117647059,"a, the, of, virus, at, from"
22074,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.117647059,"of, the, been, in, from, and"
22075,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.117647059,"the, in, to, other"
22076,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.117647059,"to, human, in, animal"
22077,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.117647059,"in, the, more, than, to, human"
22078,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.117647059,"in, other, closely, related, to, the"
22079,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.117647059,"animal, in, the, other"
22080,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.117647059,"was, in, and, sars-cov-2, at, the"
22081,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.117647059,"genomic, in, sars-cov-2, than, the, and"
22082,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.117647059,"on, of, and, sars-cov-2, to, humans"
22083,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.117647059,"in, and, to, humans, from, at"
22084,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.117647059,"from, at, and, to, of, on"
22085,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.117647059,"in, of, at, from, humans, were, to, and"
22086,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.117647059,"from, in, at, sars-cov-2, of, on"
22087,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.117647059,"evidence, the, of, natural"
22088,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.117647059,"and, were, to, of, the, huanan"
22089,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.117647059,"cases, and, the, huanan, market,, that, was, of"
22090,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.117647059,"sars-cov-2, a, and, in, an, animal"
22091,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.117647059,"have, to, the, multiple, of, animals, samples, that"
22092,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.117647059,"of, the, sars-, cov-2, that, sars-cov-2"
22093,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.117647059,"the, of, to, that, sars-, cov-2"
22094,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.117647059,"that, a, the, humans, early, cases, of, in, different, also, have, to"
22095,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.117647059,"it, is, that, are, sars-cov-2, to"
22096,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.117647059,"sars-cov-2, that, with, infected, on, the"
22097,"genetic sequencing has been used to show that  

COVID-19 exists in bats,",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.117647059,"genetic, to, that, in"
22098,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.117647059,"in, the, as, a, that, from, humans, to"
22099,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.117647059,"a, are, to, that, the, of, from, this"
22100,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.117647059,"found, that, are, to, a, the, of, sars-cov-2."
22101,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.117647059,"and, that, a, of, the, virus, is, most"
22102,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.117647059,"from, an, animal, to, a, in"
22103,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.117647059,"in, is, to, from"
22104,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.117647059,"is, to, in, covid-19"
22105,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.117647059,"is, naturally, occurring, a, that, in"
22106,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.117647059,"in, a, to, that, naturally, animal"
22107,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.117647059,"samples, the, of, multiple, that, animals, have, to"
22108,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.117647059,"to, with, the, and, bat, virus"
22109,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.117647059,"to, the, virus, has, and, was"
22110,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.117647059,"the, virus, to, with"
22111,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.117647059,"the, a, as, to"
22112,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.117647059,"is, the, huanan, seafood"
22113,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.117647059,"and, a, zoonotic, that"
22114,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.117647059,"and, that, origin, in"
22115,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.117647059,"and, of, the, in"
22116,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.117647059,"in, the, and, of"
22117,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.117647059,"through, animals, to, and"
22118,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.117647059,"to, coronavirus, and, very"
22119,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.117647059,"to, a, studies, high, and, bat"
22120,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.117647059,"coronavirus, and, very, to"
22121,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.117647059,"the, a, and, bat"
22122,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.117647059,"that, the, bat, covid-19, a, to"
22123,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.117647059,"the, known, to, of"
22124,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.117647059,"to, the, as, of"
22125,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.117647059,"to, the, be, of, as, intermediate"
22126,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.117647059,"of, was, to, the"
22127,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.117647059,"bats, a, of, the"
22128,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.117647059,"the, of, possible, a"
22129,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.117647059,"a, with, the, in"
22130,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.117647059,"a, study, in, the, of, bats"
22131,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.117647059,"the, to, that, in, with, of"
22132,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.117647059,"to, this, that, the, virus, of"
22133,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.117647059,"that, the, virus, and, to, from"
22134,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.117647059,"is, and, that, of, to, an"
22135,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.117647059,"to, the, has, from, and, an"
22136,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.117647059,"the, bats, as, a, from, and"
22137,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.117647059,"to, the, sars-cov-2, from, and, as"
22138,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.117647059,"was, bats, and, as"
22139,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.117647059,"the, was, from, a, and, to"
22140,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.117647059,"the, genome, of, and, bat, that, a, to"
22141,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.117647059,"to, of, which, from, a, with"
22142,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.117647059,"the, of, to, bat, that, for"
22143,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.117647059,"a, genome, from, that, the, virus, to, of"
22144,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.117647059,"the, of, identity, to, that, from"
22145,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.117647059,"the, and, has, a, to, that, bat, of"
22146,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Bats have been reported as being the rich source of 

coronaviruses",0.117647059,"the, been, bats, of"
22147,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.117647059,"the, from, a, pangolin"
22148,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.117647059,"the, has, been, a"
22149,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.117647059,"to, the, coronavirus, have, been, a"
22150,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.117647059,"a, from, identified, sars-cov-2"
22151,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.117647059,"the, from, with, sars-cov-2"
22152,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.117647059,"sars-cov-2, and, with, the, of, from"
22153,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.117647059,"and, their, to, the, of, sars-cov-2"
22154,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.117647059,"from, with, the, sars-cov-2"
22155,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.117647059,"a, virus, to, the"
22156,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.117647059,"the, virus, to, sars-cov-2"
22157,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.117647059,"the, bat, and, to"
22158,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.117647059,"the, human, to, and"
22159,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.117647059,"is, the, of, to"
22160,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.117647059,"of, to, intermediate, is, pangolin, the"
22161,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.117647059,"the, of, to, and"
22162,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.117647059,"be, possible, bat, to, of, and"
22163,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.117647059,"of, sars-cov-2, humans, and, to, on"
22164,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.117647059,"the, sequences, of, and, which, sars-cov-2"
22165,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.117647059,"the, and, is, of, suggesting, to"
22166,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.117647059,"sars-cov-2, is, to, have, the, which"
22167,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.117647059,"the, of, that, sars-cov-2, is, animal"
22168,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.117647059,"sars-cov-2, of, based, on, the, and, to, analysis"
22169,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.117647059,"a, and, the, from, in, bats"
22170,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.117647059,"are, the, a, and"
22171,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.117647059,"in, the, virus, to, and, a"
22172,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.117647059,"the, and, in, bats, from, to"
22173,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.117647059,"are, a, to, in, the, and"
22174,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.117647059,"a, virus, the, and"
22175,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.117647059,"and, that, have, from, the, at"
22176,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.117647059,"at, humans, from, in, and, to"
22177,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.117647059,"the, virus, to, that, and, from"
22178,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.117647059,"the, that, virus, to, a, and"
22179,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.117647059,"in, the, animals, from, that, at, market, virus, to, infected, a, and"
22180,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.117647059,"the, market, that, have, in, to, epidemiologists, and, who, a"
22181,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.117647059,"the, at, that, a, virus, in"
22182,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.117647059,"the, zoonotic, (i.e.,, that"
22183,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.117647059,"the, virus, was, has, and, to"
22184,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.117647059,"., bats, are, of, virus, the"
22185,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.117647059,"but, virus, to, bats, of, and, are, they"
22186,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.117647059,"the, to, covid-19, which, animals, is"
22187,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.117647059,"was, in, the, virus, is, to, of, bats"
22188,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.117647059,"the, has, of, virus, and, to"
22189,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.117647059,"the, of, to, was, transmitted, bats"
22190,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.117647059,"the, and, has, in, to, are, of, but"
22191,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.117647059,"genetic, that, in, to"
22192,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.117647059,"that, to, has, been"
22193,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.117647059,"that, has, been, in"
22194,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.117647059,"that, the, virus, was"
22195,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.117647059,"that, the, of, at, as, a"
22196,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.117647059,"that, a, virus, of"
22197,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.117647059,"the, in, humans, animals"
22198,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.117647059,"believe, the, to, animals"
22199,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.117647059,"to, humans, and, the"
22200,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.117647059,"in, the, that, its"
22201,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.117647059,"that, origin, in, and"
22202,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.117647059,"that, the, and, is"
22203,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.117647059,"the, to, that, sars-cov"
22204,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.117647059,"in, that, the, virus, is, to"
22205,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.117647059,"and, the, huanan, seafood, market,, was, of, in"
22206,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.117647059,"the, and, bat, cov"
22207,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.117647059,"also, cov, and, the"
22208,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.117647059,"and, to, bats, of"
22209,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.117647059,"bats, to, virus, be"
22210,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.117647059,"t, is, that, to"
22211,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.117647059,"sequence, with, bat, the, of, as, and, sars-cov"
22212,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.117647059,"could, be, the, reservoir"
22213,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.117647059,"have, been, in, or"
22214,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.117647059,"from, the, market, in"
22215,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.117647059,"was, and, patients, were, at, a, seafood, market, on, december"
22216,"Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.117647059,"the, reservoir, could, be"
22217,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.117647059,"the, have, in, of, that, animals, a, china"
22218,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.117647059,"the, that, be, at"
22219,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.117647059,"market, that, positive, for, palm, civet, the, suggesting"
22220,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.117647059,"a, viruses, bat, that, the, of"
22221,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.117647059,"possible, that, a, of, the, genomic"
22222,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.117647059,"of, a, that, the, bat, sars-like"
22223,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.117647059,"the, sars-cov-2, to, of, bat, human"
22224,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.117647059,"of, the, sars-cov-2, genome"
22225,"the close relation  

between SARS coronavirus and 2019-nCoV","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.117647059,"the, close"
22226,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.117647059,"sars-cov-2, which, for, to, ace2, a, that, 2), and, the"
22227,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.117647059,"to, by, is, which, sars-cov-2, the"
22228,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.117647059,"of, the, genome, bat, sars-like, coronavirus"
22229,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.117647059,"to, be, of, and, the, transmission"
22230,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.117647059,"with, bats, to, be, the, of"
22231,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.117647059,"another, suggested, be, the, of, and"
22232,Genetic evidence suggesting otherwise is yet to be presented.,"According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.117647059,"is, to"
22233,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.117647059,"the, sars-cov, as, of, bat, and, sequence, with"
22234,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.117647059,"the, genetic, similarity, of, sars-cov-2, with"
22235,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.117647059,"that, sars-cov-2, the, with, bat, cov"
22236,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.117647059,"another, bat, the, of, sars-cov-2, and"
22237,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.117647059,"that, the, it, been"
22238,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.117647059,"of, the, are, from"
22239,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.117647059,"the, of, has, human"
22240,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.117647059,"of, bat, from, coronaviruses"
22241,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.117647059,"in, the, of, as"
22242,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.117647059,"a, from, the, pangolin"
22243,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.117647059,"the, of, are, from"
22244,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.117647059,"the, in, those, as"
22245,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.117647059,"is, on, bat, receptor, binding, by"
22246,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.117647059,"the, bats, most, reservoir"
22247,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.117647059,"that, virus, transmitted, to"
22248,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.117647059,"a, to, the, virus"
22249,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.117647059,"bats, are, to, the"
22250,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.117647059,"coronaviruses, are, to, the"
22251,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.117647059,"the, sars-cov-2, to, coronaviruses"
22252,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.117647059,"sars-cov-2, to, bats, the"
22253,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.117647059,"the, to, of, is, in, coronaviruses"
22254,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.117647059,"to, the, of, from"
22255,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.117647059,"is, of, the, in"
22256,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.117647059,"is, in, from, to"
22257,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.117647059,"to, the, in, of"
22258,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.117647059,"from, the, of, in"
22259,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.117647059,"of, in, to, the"
22260,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.117647059,"coronaviruses, to, the, of"
22261,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.117647059,"that, all, bat, in"
22262,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.117647059,"in, the, genus, rhinolophus"
22263,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.117647059,"found, are, and, the"
22264,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.117647059,"in, have, to, and"
22265,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.117647059,"the, animal, and, market, into, in"
22266,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.117647059,"the, to, and, human"
22267,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.117647059,"into, the, in, to"
22268,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.117647059,"the, from, an, to"
22269,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.117647059,"infected, from, in, the, market, or, and, source, animal, may"
22270,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.117647059,"sars-cov-2, that, and, is"
22271,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.117647059,"that, a, has, sars-cov-2"
22272,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.117647059,"that, and, sars-cov-2, is"
22273,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.117647059,"sars-cov-2, and, or, origin"
22274,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.117647059,"suggests, that, natural, and"
22275,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.117647059,"from, species, infected, and"
22276,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.117647059,"sars-cov-2, and, is, that"
22277,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.117647059,"the, and, sars-cov-2, is"
22278,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.117647059,"the, that, sars-cov-2, and"
22279,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.117647059,"the, sars-cov-2, that, and"
22280,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.117647059,"from, the, that, sars-cov-2"
22281,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.117647059,"an, is, to, that, of, and"
22282,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.117647059,"is, that, to, of, and, it"
22283,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.117647059,"to, that, of, and, is, be"
22284,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.117647059,"of, that, sars-cov-2, more, likely, to"
22285,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.117647059,"is, and, it, an, to, of"
22286,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.117647059,"indicated, that, virus, of"
22287,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.117647059,"of, the, that, and"
22288,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.117647059,"the, genome, of, coronavirus, sars-like, bat"
22289,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.117647059,"with, the, of, genome, sars-like, and"
22290,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.117647059,"the, genome, was, bat"
22291,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.117647059,"of, the, and, with, in, virus, ace2, animals."
22292,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.117647059,"analysis, the, with, of, virus, and"
22293,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",COVID-19 is a zoonotic virus,0.117647059,"virus, is"
22294,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.117647059,"the, of, covid-19, with"
22295,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.117647059,"bats, the, to, be, with, of"
22296,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.117647059,"virus, genome, of, with"
22297,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.117647059,"bats, the, reservoir, to"
22298,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.117647059,"to, are, coronaviruses, the"
22299,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.117647059,"the, that, to, coronaviruses"
22300,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.117647059,"and, to, belonging, the"
22301,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.117647059,"the, intermediate, to, be, of, as"
22302,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.117647059,"coronaviruses, to, the, that"
22303,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.117647059,"and, bat, has, of"
22304,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.117647059,"bat, and, the, of"
22305,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.117647059,"the, of, identity, with"
22306,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.117647059,"the, sars, and, viruses,, very, to"
22307,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.117647059,"to, the, that, as, of, from"
22308,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.117647059,"of, the, genome, that, and, novel"
22309,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.117647059,"and, bat, very, to, the, of"
22310,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.117647059,"of, the, sars, that"
22311,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","no modifications were  

recorded for nonstructural proteins NSP7, NSP13  

and the structured and accessory proteins p6 and 8b.",0.117647059,"no, recorded, and, the"
22312,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.117647059,"of, amino, acid, with"
22313,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.117647059,"of, in, sequences, with"
22314,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.117647059,"amino, acid, in, of"
22315,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.117647059,"the, sars-cov-2, and, other"
22316,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.117647059,"human, in, to, animal"
22317,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.117647059,"from, a, that, in"
22318,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.117647059,"further, the, from, and"
22319,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","the close relation  

between SARS coronavirus and 2019-nCoV",0.117647059,"between, and"
22320,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.117647059,"a, seafood, at, was, on, december, and, market, were, patients"
22321,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.117647059,"the, to, sars-cov, that"
22322,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.117647059,"the, of, sars-cov-2, bat, (rhinolophus, and"
22323,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.117647059,"the, of, sars-cov-2, and, has, from"
22324,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.117647059,"the, of, from, a, virus, with"
22325,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.117647059,"that, sars-cov-2, is, bat"
22326,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.117647059,"that, sars-cov-2, from, a"
22327,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.117647059,"that, from, a, in"
22328,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.117647059,"sars-cov-2, from, a, in, that, originate"
22329,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.117647059,"that, sars-cov-2, in, from"
22330,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.117647059,"that, may, sars-cov-2, in"
22331,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.117647059,"a, bat, sars-cov-2, in"
22332,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.117647059,"that, sars-cov-2, this, from"
22333,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.117647059,"that, in, pangolin, the, for, of"
22334,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.117647059,"the, genome, of, sars-cov-2"
22335,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.117647059,"the, genome, of, novel, that, and"
22336,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.117647059,"the, with, and, sars-cov-2"
22337,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.117647059,"coronaviruses, are, viruses, in, a, of"
22338,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.117647059,"the, a, genome, of, to, that, and, bat"
22339,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.117647059,"that, a, of, similar, to, and, are, the"
22340,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.117647059,"the, other, sars-cov-2, and"
22341,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.117647059,"sars-cov-2, the, of, and"
22342,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.117647059,"the, to, of, sars-"
22343,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.117647059,"sars-cov-2, bats, and, can, be, to"
22344,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.117647059,"a, coronaviruses, to, in, may, sars-cov-2, bat, and"
22345,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.117647059,"and, a, between, sars-cov-2, in, which, is, to"
22346,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.117647059,"at, that, the, as, of, a"
22347,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.117647059,"the, of, that, this, intermediate, was"
22348,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.117647059,"the, of, to, that, this, was"
22349,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.117647059,"the, most, to, is"
22350,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.117647059,"a, team, with, which, sars-cov-2, the"
22351,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.117647059,"sars-cov-2, has, similarity, with"
22352,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.117647059,"has, been, to, that"
22353,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.117647059,"to, and, of, it, is, that"
22354,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.117647059,"that, a, was, the, of, to"
22355,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.117647059,"to, the, of, sars-"
22356,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.117647059,"in, a, of, that, the, with"
22357,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.117647059,"the, sars-, cov-2, in"
22358,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.117647059,"and, are, coronaviruses, to"
22359,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.117647059,"of, be, the, that"
22360,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.117647059,"the, of, that, host"
22361,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.117647059,"that, a, of, the"
22362,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.117647059,"these, a, of, the"
22363,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.117647059,"that, a, the, of"
22364,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.117647059,"sars-cov-2, the, with, of"
22365,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.117647059,"cases, the, huanan, seafood, market,, be, that, of"
22366,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.117647059,"the, analysis, our, that"
22367,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.117647059,"the, huanan, seafood, is"
22368,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.117647059,"was, the, of, sars-cov-2, and, to"
22369,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.117647059,"belonging, to, the, and"
22370,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.117647059,"in, the, of, sars-cov-2, was, to"
22371,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.117647059,"ratg13,, from, a, to, in, the"
22372,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.117647059,"the, in, was, also"
22373,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.117647059,"in, the, rhinolophus, horseshoe"
22374,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.117647059,"viruses, in, closely, related"
22375,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.117647059,"viruses, have, been, in, bats, rhinolophus"
22376,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.117647059,"the, at, that, be"
22377,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.117647059,"the, of, be, spillover"
22378,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.117647059,"the, of, that, reservoir"
22379,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.117647059,"or, in, have, been"
22380,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.117647059,"of, cleavage, in, furin, such, naturally"
22381,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.117647059,"the, between, sars-cov-2, and, a, of"
22382,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.117647059,"and, a, the, natural, of, as"
22383,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.117647059,"from, the, of, sars-cov-2"
22384,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.117647059,"the, natural, of, and, between, pangolins"
22385,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.117647059,"the, between, and, of"
22386,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.117647059,"related, to, which, similar, sars-cov-2, the"
22387,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.117647059,"the, to, that, sequence, was, but"
22388,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.117647059,"a, the, was, by"
22389,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.117647059,"human, to, the, than"
22390,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.117647059,"the, to, believe, animals"
22391,"natural selection in humans  

following zoonotic transfer","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.117647059,"in, zoonotic"
22392,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.117647059,"the, species, to, as, of, and"
22393,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.117647059,"are, ., of, the, virus, bats"
22394,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.117647059,"by, a, of, virus, are, the"
22395,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K",0.117647059,"with, to, human, than"
22396,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.117647059,"the, and, a, of, in, bat"
22397,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.117647059,"the, bat, and, a"
22398,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.117647059,"and, bat, the, of"
22399,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.117647059,"were, found, to, related, that, bats, are, hosts"
22400,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.117647059,"a, from, bats, and, the, as"
22401,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.117647059,"of, the, genome, and, with, sars-like"
22402,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.117647059,"the, natural, and, it, with, of"
22403,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.117647059,"a, in, the, with"
22404,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.117647059,"a, the, of, possible"
22405,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.117647059,"the, spillover, be, of"
22406,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.117647059,"the, of, to, human, most, a"
22407,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.117647059,"that, sars-cov-2, is, or"
22408,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.117647059,"of, that, the, covid-19, is, or"
22409,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.117647059,"the, any, to, sars-cov-2"
22410,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.117647059,"the, into, in, to"
22411,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.117647059,"to, any, the, sars-cov-2"
22412,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.117647059,"that, to, is, in, sars-cov-2, the"
22413,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.117647059,"the, related, to, is"
22414,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.117647059,"in, that, the, is, related, to"
22415,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.117647059,"human, in, more, to, the, than"
22416,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.117647059,"and, the, virus, to, a, in"
22417,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.117647059,"and, the, of, to, it, that, sars-cov-2, is"
22418,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.117647059,"a, change, within, the, to, sars-cov-2"
22419,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.117647059,"the, of, has, a, human, and"
22420,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.117647059,"the, pangolin, is, to, of, intermediate"
22421,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.117647059,"direct, transmission, to, humans, with, of, in, bats"
22422,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.117647059,"sequences, and, of, were, in, which"
22423,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.117647059,"the, of, and, sequences, sars-cov-2, which"
22424,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.117647059,"from, in, with, sars-cov-2, the, of"
22425,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.117647059,"that, virus, of, a"
22426,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.117647059,"that, sars-cov-2, has, a"
22427,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.117647059,"with, genome, of, virus"
22428,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.117647059,"the, is, to, that"
22429,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.117647059,"the, is, that, to"
22430,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.117647059,"the, is, sars-cov-2, to"
22431,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.117647059,"to, that, the, is"
22432,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.117647059,"the, to, shares, identity"
22433,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.117647059,"the, to, human, virus"
22434,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.117647059,"the, virus, with, to"
22435,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.117647059,"virus, identity, with, the"
22436,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.117647059,"the, with, virus, to"
22437,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.117647059,"the, identity, to, from"
22438,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.117647059,"animal, by, the, not"
22439,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.117647059,"sars-, cov-2, the, of, that, sars-cov-2"
22440,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.117647059,"the, of, sars-cov-2, rdrp"
22441,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.117647059,"sars-cov-2, the, shows, that, is, of"
22442,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.117647059,"of, sars-, cov-2, analysis"
22443,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.117647059,"that, sars-cov-2, the, same"
22444,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.117647059,"sars-cov-2, in, to, of"
22445,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.117647059,"of, the, rdrp, sars-cov-2"
22446,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.117647059,"the, sars-cov-2, in, homology"
22447,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.117647059,"of, sars-cov-2, has, the"
22448,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.117647059,"the, has, an, to, and, from"
22449,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.117647059,"to, sars-cov-2, from, and, the, as"
22450,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","bats are also important reservoir species for a great 

range of coronaviruses",0.117647059,"bats, are, of, species"
22451,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.117647059,"and, were, to, of, in, the"
22452,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.117647059,"the, and, with, bat"
22453,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.117647059,"amino, acid, with, of"
22454,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.117647059,"is, most, similar, to, the, and"
22455,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.117647059,"the, protein, to, human, ace2, a"
22456,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.117647059,"the, homology, with, sars-cov-2"
22457,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.117647059,"the, homology, sars-cov-2, in"
22458,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.117647059,"the, of, it, is, to, that, sars-cov-2, and"
22459,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.117647059,"and, species, variety, in, the, of"
22460,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.117647059,"that, the, rbd, with, to, than"
22461,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.117647059,"the, and, amino, acids, for, sars-cov-2"
22462,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.117647059,"that, than, the, sars-cov-2, to, may, be, with, in, and"
22463,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.117647059,"and, the, that, was, sars-cov-2, in, study, a"
22464,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.117647059,"that, sars-cov-2, laboratory, a"
22465,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.117647059,"that, caused, to, in"
22466,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.117647059,"able, to, sars-cov-2, the"
22467,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.117647059,"the, to, sars-cov-2, change, within, a"
22468,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.117647059,"sars-cov-2, be, a, the"
22469,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.117647059,"is, sars-cov-2, and, to, the, between"
22470,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.117647059,"the, as, a, to"
22471,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.117647059,"the, to, a, from"
22472,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.117647059,"and, at, the, in"
22473,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.117647059,"to, sars-cov-2, the, and"
22474,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.117647059,"the, genetic, of, that, sequences, from"
22475,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.117647059,"the, of, that, intermediate, was, this"
22476,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.117647059,"that, the, host, of"
22477,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",Historical Precedent; SARS & MERS,0.117647059,"sars, mers"
22478,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.117647059,"found, sars-cov-2, to, bat"
22479,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.117647059,"to, coronavirus, found, in, with, sars-cov-2"
22480,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.117647059,"to, sars-cov-2, bat, in"
22481,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.117647059,"with, sars-cov-2, in, bat"
22482,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.117647059,"sars-cov-2, bat, to, in"
22483,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.117647059,"sars-cov-2, with, similarity, to"
22484,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",Wet Market animals maintained in poor conditions,0.117647059,"in, market"
22485,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.117647059,"from, in, the, market"
22486,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.117647059,"the, of, in, from"
22487,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.117647059,"that, sars-cov-2, the, from"
22488,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.117647059,"the, of, sars-cov-2, from"
22489,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.117647059,"from, in, the, of"
22490,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.117647059,"the, that, of, market, in, environmental"
22491,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.117647059,"sars-cov-2, originate, from, a, that, in"
22492,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.117647059,"sars-cov-2, the, and, cleavage, in, coronaviruses, that, of"
22493,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.117647059,"in, a, of, sars-cov-2, to, with, that, events"
22494,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.117647059,"of, a, virus, at, the, from"
22495,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.117647059,"that, the, of, genome, a, covid-19"
22496,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.117647059,"the, of, to, a, closely, related, in, result, virus, is"
22497,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.117647059,"in, the, of, a, virus, to, closely, related"
22498,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.117647059,"virus, in, is, sars-cov-2, the, of"
22499,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Bats are the second  

largest order of mammals, with over 1,230 species.",0.117647059,"the, of, are, with"
22500,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.117647059,"the, species, to, serve, as, reservoir, bat, and"
22501,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",Coronaviruses account for over 30% of the world’s viruses.,0.117647059,"the, for"
22502,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.117647059,"of, the, belongs, which"
22503,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.117647059,"of, bats, the, as"
22504,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.117647059,"of, the, and, sars"
22505,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.117647059,"of, the, and, viruses"
22506,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.117647059,"as, intermediate, to, and, the, species"
22507,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.117647059,"sars-cov-2, and, the, of, bat, (rhinolophus"
22508,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.117647059,"the, of, to, and, species, as"
22509,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.117647059,"serve, as, the, reservoir, to, bat, species, and"
22510,hese close genetic relations suggest that they all have their ecological origin in bat populations,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.117647059,"that, all, in, bat"
22511,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.117647059,"bat, to, sars-cov-2, in"
22512,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.117647059,"that, to, and, are, the, sars-cov-2"
22513,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.117647059,"viruses, to, the, in, and, china"
22514,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.117647059,"in, variety, of, species, and, the"
22515,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.117647059,"the, bat, species, in"
22516,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.117647059,"and, are, bat, in, a, viruses"
22517,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.117647059,"the, viruses, and, are, of, bat"
22518,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.117647059,"and, are, the, of, species, by"
22519,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.117647059,"the, between, and, of, suggesting, a"
22520,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.117647059,"are, a, and, this, in, the"
22521,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.117647059,"the, to, a, of, genetic, in, bat, recombination"
22522,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.117647059,"to, the, that, as, a, of"
22523,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.117647059,"in, a, that, the, closely, to"
22524,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.117647059,"the, covid-19, to, bat, that, a"
22525,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.117647059,"a, of, viruses, in, to, the"
22526,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.117647059,"the, as, a, species, of, that, to, bat"
22527,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.117647059,"the, is, result, of, to, a, closely, related, virus, in"
22528,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.117647059,"the, of, this, that, is, a, virus, in, populations, for"
22529,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.117647059,"to, have, with, of, which, from"
22530,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.117647059,"a, of, which, to, with, from"
22531,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.117647059,"have, a, of, with, to, sars-cov-2"
22532,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.117647059,"the, sars-cov-2, to, which, is, by"
22533,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.117647059,"the, which, sars-cov-2, related, to, similar"
22534,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.117647059,"the, by, to, sars-cov-2, is, bat, closest, as"
22535,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.117647059,"a, the, was, it, by, other"
22536,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.117647059,"in, closely, related, to, the, other"
22537,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.117647059,"the, sars-cov-2, at, was, in, and"
22538,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.117647059,"a, team, the, which, with, sars-cov-2"
22539,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.117647059,"in, laos, which, are, to, sars-cov-2, both, and"
22540,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.117647059,"similarity, to, sars-cov-2, the, spike, of"
22541,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.117647059,"of, the, also, are, by, to"
22542,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.117647059,"sars-, cov-2, the, of, that, to"
22543,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.117647059,"to, the, rbd, that, is, of"
22544,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.117647059,"found, that, similar, to, a, on, the, of"
22545,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.117647059,"of, the, that, to"
22546,"In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.117647059,"to, with, than, human"
22547,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.117647059,"that, to, than, the, rbd, with"
22548,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","This suggests that the BANAL series may be able to directly infect  

humans.",0.117647059,"that, to, be, the"
22549,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","This suggests that the BANAL series may be able to directly infect  

humans.",0.117647059,"suggests, that, the, to"
22550,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","This suggests that the BANAL series may be able to directly infect  

humans.",0.117647059,"that, the, suggests, this"
22551,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.117647059,"the, spike, s2, of, is, in"
22552,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.117647059,"of, also, the, in"
22553,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.117647059,"viruses, have, a, of"
22554,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.117647059,"two, viruses, the, have, is, and"
22555,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.117647059,"and, for, sars-cov-2, the, amino, acids"
22556,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.117647059,"bats, and, was, as"
22557,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.117647059,"the, sars-cov-2, to, be, is, in"
22558,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.117647059,"to, sars-cov-2, the, virus"
22559,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.117647059,"the, covid-19, is, of"
22560,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.117647059,"the, genomic, sars-cov-2, than, in, and"
22561,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.117647059,"sars-cov-2, a, and, coronaviruses, bat, to, may, in"
22562,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.117647059,"coronaviruses, in, share, are, more, to, sars-cov-2, and"
22563,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.117647059,"a, recent, bat, in, coronaviruses, sars-cov-2"
22564,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.117647059,"covid-19, be, in, the, that, sars-cov-2"
22565,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.117647059,"at, the, to, was, from, wuhan"
22566,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.117647059,"at, of, from, and, to, on"
22567,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.117647059,"to, a, from, and, was, the"
22568,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.117647059,"early, cases, in, humans, also, different, the, of, that, a, have, to"
22569,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.117647059,"the, market, positive, for, suggesting, that, civet, palm"
22570,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.117647059,"that, the, virus, in, and, to, from, infected, animals, at, a, market"
22571,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.117647059,"the, in, of, to, that, this, virus, humans."
22572,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.117647059,"and, human, that, a, of, the, virus, likely"
22573,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.117647059,"the, guangdong, live, from, and, were, in, with, these, by, however,, of, a, as, to, that, positive, infected, at, one"
22574,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.117647059,"were, at, of, humans, from, in, and, to"
22575,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.117647059,"the, that, in, a, as, to, from, humans"
22576,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.117647059,"the, of, to, a, closely, related, virus, in"
22577,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.117647059,"the, and, of, a, to, that, were, in, sars, palm, more, infected, than, at"
22578,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.117647059,"at, a, and, in, the, that, to, sars"
22579,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.117647059,"the, from, animal, source, in, market, or, infected, and, may"
22580,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.117647059,"epidemiologists, have, that, the, in, and, to, who, a, market"
22581,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.117647059,"in, the, of, palm, sars, a, at, that, infected, were, to, and, more, than"
22582,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.117647059,"of, the, were, to, huanan, and"
22583,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.117647059,"and, the, of, which, shows, a"
22584,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.117647059,"the, of, and, suggesting, is, to"
22585,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.117647059,"of, and, suggesting, a, between, the"
22586,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.117647059,"this, and, are, a, in, the"
22587,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.117647059,"in, the, sars, a, at, that, to, and"
22588,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.117647059,"within, the, and, many, sequences, are"
22589,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.117647059,"with, many, within, and, is, that"
22590,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.117647059,"environmental, the, market, that, of, in"
22591,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.117647059,"of, the, cases, huanan, market,, and, that, was"
22592,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.117647059,"huanan, seafood, market,, in, the, was, and, of"
22593,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.117647059,"of, cases, be, the, huanan, seafood, market,, that"
22594,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.117647059,"a, study, that, the, was, and, in, sars-cov-2"
22595,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.117647059,"pandemic, natural, the, virus, into, humans"
22596,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.117647059,"the, on, that, infected, with, sars-cov-2"
22597,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.117647059,"is, the, with, sars-cov-2, that, for"
22598,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.117647059,"a, the, that, sars-cov-2, pandemic, for"
22599,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","expended to make the simple point 

that COVID-19 had a natural origin.",0.117647059,"to, a, that, the"
22600,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","expended to make the simple point 

that COVID-19 had a natural origin.",0.117647059,"the, that, to, a"
22601,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","expended to make the simple point 

that COVID-19 had a natural origin.",0.117647059,"to, that, natural, the"
22602,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.117647059,"were, bats, in, asian"
22603,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.117647059,"that, sars-cov-2, in, bats"
22604,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.117647059,"in, sars-cov-2, were, found, to, that"
22605,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.117647059,"of, a, viruses, in"
22606,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.117647059,"the, of, in, viruses, a, to"
22607,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.117647059,"natural, of, the, in, a, to"
22608,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.117647059,"a, sars-cov-2, zoonotic, origin"
22609,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.117647059,"in, an, animal, and, a, sars-cov-2"
22610,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.117647059,"a, natural, origin, was"
22611,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.117647059,"sars-cov-2, has, origin, or"
22612,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.117647059,"the, virus, identity, with"
22613,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.117647059,"bat, with, sars-cov-2, in"
22614,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.117647059,"that, a, virus, with, the, sars-cov-2"
22615,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.117647059,"is, that, sars-cov-2, or"
22616,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.117647059,"a, is, the, to, that, human"
22617,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.117647059,"to, the, of, most, a, human"
22618,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.117647059,"to, a, the, protein, human, ace2"
22619,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.117647059,"the, of, to, is, likely, that"
22620,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.117647059,"the, to, a, is, most, likely"
22621,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.117647059,"the, of, to, that, sars-cov-2, not"
22622,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.117647059,"a, that, of, sars-cov-2"
22623,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.117647059,"a, that, laboratory, sars-cov-2"
22624,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.117647059,"that, a, of, is"
22625,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.117647059,"that, sars-cov-2, a, of"
22626,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.117647059,"genetic, is, virus, that"
22627,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","natural selection in humans  

following zoonotic transfer",0.117647059,"zoonotic, in"
22628,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.117647059,"the, for, of, to, that, bat"
22629,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.117647059,"that, bats, hosts, for"
22630,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.117647059,"that, of, to, the, hosts, for"
22631,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.117647059,"the, that, to, in, it, is"
22632,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.117647059,"ratg13,, the, to, in, from, a"
22633,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.117647059,"of, the, shows, that, sars-cov-2, is"
22634,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.117647059,"the, to, sars-cov-2, similarity, of, spike"
22635,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.117647059,"is, that, the, for, sars-cov-2, to"
22636,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.117647059,"a, shows, and, of, which, the"
22637,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.117647059,"a, of, the, possible, genomic, that"
22638,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.117647059,"virus, to, sars-cov-2, in"
22639,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.117647059,"the, of, that, was, to, this"
22640,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.117647059,"the, of, that, virus, in, this, to, humans."
22641,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.117647059,"t, that, sars-cov-2, in"
22642,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.117647059,"we, to, sars-cov-2, the"
22643,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.117647059,"that, sars-cov-2, very, to"
22644,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.117647059,"sars-cov-2, from, pangolins, and, of, coronaviruses"
22645,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.117647059,"sars-cov-2, of, in, the, and, that, cleavage, coronaviruses"
22646,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.117647059,"the, sequence, that, was, to, but"
22647,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.117647059,"that, a, the, covid-19, of, genome"
22648,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.117647059,"analysis, that, the, a"
22649,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.117647059,"the, that, animal, in, this, covid-19"
22650,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.117647059,"of, the, showed, bats"
22651,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.117647059,"the, and, which, that"
22652,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.117647059,"from, to, and, the"
22653,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.117647059,"the, evidence, that, from"
22654,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.117647059,"that, the, of, is, a, bat"
22655,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.117647059,"is, that, the, of, or, covid-19"
22656,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.117647059,"the, covid-19, for, a, from, is"
22657,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.117647059,"of, viruses, have, a"
22658,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.117647059,",, of, amino, the, indicating, that"
22659,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.117647059,"virus, that, transmitted, to"
22660,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.117647059,"that, originated, in, bats"
22661,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.117647059,"a, viruses, are, of"
22662,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.117647059,"of, a, group, viruses"
22663,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.117647059,"that, to, caused, in"
22664,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.117647059,"that, be, are, in"
22665,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.117647059,"an, animal, in, to"
22666,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.117647059,"to, in, an, intermediate"
22667,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.117647059,"the, in, to, market"
22668,Wet Market animals maintained in poor conditions,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.117647059,"market, in"
22669,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.117647059,"to, the, is, be"
22670,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.117647059,"is, to, in, the"
22671,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.117647059,"that, in, the, was"
22672,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.117647059,"of, been, that, the"
22673,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.117647059,"of, the, was, it, is, to"
22674,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.117647059,"the, and, is, most, similar, to"
22675,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.117647059,"and, of, is, the, for, to"
22676,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.117647059,"analysis, that, the, is"
22677,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.117647059,"a, coronavirus, the, been, to, have"
22678,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.117647059,"that, the, in, china, have, animals, a, of"
22679,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.117647059,"viruses, have, been, in, rhinolophus, bats"
22680,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.117647059,"the, and, viruses, to, in, china"
22681,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.117647059,"and, a, of, in, the, viruses, to, 2"
22682,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.117647059,"the, natural, of, between, pangolins, and"
22683,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.117647059,"that, the, of, in, to, with"
22684,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.117647059,"in, the, rhinolophus, genus"
22685,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.117647059,"the, a, of, these"
22686,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.117647059,"in, the, horseshoe, rhinolophus"
22687,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.117647059,"several, that, the, natural"
22688,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.117647059,"in, the, sars-, cov-2"
22689,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.117647059,"bat, species, in, the"
22690,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.117647059,"direct, transmission, of, bats, to, humans, in, with"
22691,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.117647059,"the, to, and, humans"
22692,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.117647059,"the, from, to, and"
22693,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.117647059,"is, to, the, and"
22694,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.117647059,"intermediate, and, the, species, masked, palm"
22695,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.117647059,"by, bats, in, the"
22696,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.117647059,"to, be, of, possible, bat, and"
22697,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.117647059,"are, they, but, to, of, virus, bats, and"
22698,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.117647059,"virus, bats, be, to"
22699,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.117647059,"bats, to, be, virus"
22700,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.117647059,"are, to, on, and, bats, or, pangolins, be"
22701,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.117647059,"of, between, and, patients"
22702,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.117647059,"of, the, and, was"
22703,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.117647059,"the, have, been, of, and, viruses"
22704,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.117647059,"and, in, been, the, of, from"
22705,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.117647059,"two, viruses, and, have, the, is"
22706,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.117647059,"in, viruses, and, sars-cov-2, guangdong, the, origin, is"
22707,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.117647059,"sars-cov-2, from, pangolins, (manis, and, of"
22708,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.117647059,"at, of, sars-cov-2, from, in, on"
22709,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.117647059,"the, of, from, in, with, sars-cov-2"
22710,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.117647059,"the, is, of, sars-cov-2, virus, in"
22711,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.117647059,"sars-cov-2, is, in, the, with, guangdong"
22712,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.117647059,"as, a, of, the, at, and, live, these, were, by, in, to, with, however,, infected, one, that, from, positive, guangdong"
22713,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.117647059,"were, in, bats, asian"
22714,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.117647059,"bats, in, by, the"
22715,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.117647059,"the, of, covid-19, outbreak"
22716,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.117647059,"of, the, covid-19, is"
22717,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.117647059,"is, that, the, a"
22718,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.117647059,"the, and, this, of"
22719,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.117647059,"animals, to, is, the, covid-19, which"
22720,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.117647059,"the, to, is, most, likely, a"
22721,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.117647059,"the, covid-19, is, a, from, for"
22722,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.117647059,"that, the, of, bat, species, as, a, to"
22723,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.117647059,"is, the, in, and"
22724,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.117647059,"the, and, in, bats"
22725,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.117647059,"the, and, to, of"
22726,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.117647059,"the, to, and, of"
22727,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.117647059,"analysis, of, sars-, cov-2"
22728,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.117647059,"the, are, also, to, by, of"
22729,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.117647059,"not, the, by, other"
22730,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.117647059,"in, the, animal, other"
22731,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.117647059,"the, animal, not, by"
22732,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.117647059,"in, to, an, intermediate"
22733,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.117647059,"sars-cov-2, is, to, a"
22734,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.117647059,"to, a, sars-cov-2, is"
22735,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.117647059,"sars-cov-2, may, that, in"
22736,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.117647059,"that, sars-cov-2, may, in"
22737,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.117647059,"sars-cov-2, a, of, the"
22738,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.117647059,"has, the, of, sars-cov-2"
22739,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.117647059,"the, of, sars-cov-2, origin."
22740,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.117647059,"that, sars-cov-2, has, the"
22741,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.117647059,"the, and, many, sars-cov"
22742,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.117647059,"the, for, reservoirs, and"
22743,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.117647059,"a, to, that, the, of, sars-cov-2, from, this"
22744,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.117647059,"in, that, sars-cov-2, t"
22745,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.117647059,"identical, the, to, was"
22746,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.117647059,"a, the, of, and, virus, that, is, most"
22747,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.117647059,"the, of, and, that, virus, a, human, likely"
22748,"According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",Genetic evidence suggesting otherwise is yet to be presented.,0.117647059,"to, is"
22749,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.117647059,"the, of, sars-cov-2, with, that, is"
22750,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.117647059,"has, the, of, human"
22751,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.117647059,"the, of, has, human, and, a"
22752,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.117647059,"and, a, of, the, viral, human"
22753,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.117647059,"to, and, their, the, of, sars-cov-2"
22754,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.117647059,"origin, of, sars-cov-2, by, the, in"
22755,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.117647059,"the, of, sars-cov-2, and, has, been"
22756,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.117647059,"sars-cov-2, has, the, of, and, to"
22757,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.117647059,"on, receptor, binding, is, by, bat"
22758,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.117647059,"to, from, and, sars-cov-2"
22759,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.117647059,"that, from, to, and"
22760,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.117647059,"of, sars-cov-2, are, bats, and, to"
22761,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.117647059,"in, laos, and, which, are, both, to, sars-cov-2"
22762,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.117647059,"are, coronaviruses, to, in, share, more, sars-cov-2, and"
22763,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.117647059,"the, as, viruses, from"
22764,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.117647059,"the, evidence, from, that"
22765,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.117647059,"with, the, of, sars-cov-2, genetic, similarity"
22766,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.117647059,"similarity, of, with, sars-cov-2"
22767,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.117647059,"of, sars-cov-2, the, origin."
22768,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.117647059,"of, sars-cov-2, and, sars-cov"
22769,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.117647059,"we, and, of, sars-cov-2"
22770,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.117647059,"that, is, in, a, naturally, occurring"
22771,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.117647059,"that, and, may, be, sars-cov-2, to, than, the, in, with"
22772,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.117647059,"the, sars-cov-2, bats, be"
22773,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.117647059,"sars-cov-2, might, be, the"
22774,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.117647059,"our, analysis, the, that"
22775,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.117647059,"the, virus, a, genome, of, to, that, from"
22776,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.117647059,"in, to, is, of, the, virus, bats, was"
22777,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.117647059,"the, that, is, in, related, to"
22778,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.117647059,"the, a, that, are, to, for"
22779,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.117647059,"are, that, it, sars-cov-2, to, is"
22780,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.117647059,"bats, to, the, reservoir"
22781,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.117647059,"to, sars-cov-2, the, that, for, is"
22782,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.117647059,"a, of, the, sars-like, bat, that"
22783,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.117647059,"the, of, which, belongs"
22784,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.117647059,"the, of, sars, and"
22785,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.117647059,"the, of, and, that, virus, a, sars, to"
22786,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.117647059,"a, and, to, of, which, the"
22787,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.117647059,"sars-cov-2, a, in, bat"
22788,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.117647059,"by, in, the, of, sars-cov-2, origin"
22789,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.117647059,"in, a, of, patients, sars-cov-2, origin"
22790,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.117647059,"sars-cov-2, is, a, between, and, to, which, in"
22791,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.117647059,"of, is, to, the, and, for"
22792,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.117647059,"viruses, to, the, 2, in, of, and, a"
22793,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.117647059,"the, of, a, human, viral, and"
22794,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.117647059,"that, are, be, in"
22795,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.117647059,"that, sars-cov-2, have, and, are, the"
22796,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.117647059,"the, of, and, that, a, are, similar, to"
22797,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.117647059,"are, a, of, virus, by, the"
22798,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.117647059,"to, of, have, a, with, sars-cov-2"
22799,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.117647059,"a, virus, that, with, the, sars-cov-2"
22800,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.117647059,"the, of, to, that, hosts, for"
22801,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.117647059,"the, able, to, sars-cov-2"
22802,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.117647059,"the, to, sars-cov-2, we"
22803,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.117647059,"in, sequences, with, of"
22804,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.117647059,"a, group, of, viruses"
22805,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.117647059,"bat, to, is, sars-cov-2"
22806,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.117647059,"the, is, that, of"
22807,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.117647059,"sars-cov-2, is, that, the"
22808,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.117647059,"the, is, of, sars-cov-2"
22809,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.117647059,"that, the, of, is"
22810,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.117647059,"on, and, are, to, pangolins, or, bats, be"
22811,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.117647059,"sars-cov-2, is, that, with, the, for"
22812,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.117647059,"the, is, sars-cov-2, at, that, cov"
22813,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.117647059,"has, sars-cov-2, and, the, of, from"
22814,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.117647059,"sars-cov-2, from, that, this"
22815,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.117647059,"been, and, the, of, sars-cov-2, has"
22816,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.117647059,"this, that, sars-cov-2, bats"
22817,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.117647059,"the, sars-cov-2, to, is, and, between"
22818,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.117647059,"viruses, the, sars-cov-2, in, origin, is, guangdong, and"
22819,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.117647059,"the, have, sars-cov-2, is, which, to"
22820,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.117647059,"in, guangdong, is, with, sars-cov-2, the"
22821,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.117647059,"are, as, the, of, is, and, in, with, that, to"
22822,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.117647059,"closest, bat, to, as, by, is, sars-cov-2, the"
22823,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.117647059,"more, than, sars-cov-2, in"
22824,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.117647059,"cov, with, bat, that, the, sars-cov-2"
22825,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.117647059,"the, that, sars-cov-2, same"
22826,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.117647059,"the, same, sars-cov-2, with"
22827,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.117647059,"sars-cov-2, has, that, the"
22828,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.117647059,"that, the, sars-cov-2, bat"
22829,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.117647059,"that, sars-cov-2, are, the"
22830,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.117647059,"the, that, are, sars-cov-2"
22831,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.117647059,"sars-cov-2, origin, and, or"
22832,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.117647059,"this, the, of, and"
22833,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.117647059,"the, of, and, probable, origin, sars-cov-2"
22834,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.117647059,"that, sars-cov-2, this, bats"
22835,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.117647059,"the, sars-cov-2, and, probable, origin, of"
22836,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.117647059,"sars-cov-2, the, of, that, to, sequences"
22837,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.117647059,"a, of, to, the, are, that, found, sars-cov-2."
22838,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.117647059,"cov, and, also, the"
22839,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.117647059,"the, are, found, and"
22840,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.117647059,"the, of, on, found, a, similar, to, that"
22841,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.117647059,"a, on, and, to, of, the"
22842,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.117647059,"more, likely, that, of, sars-cov-2, to"
22843,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.117647059,"has, similarity, with, sars-cov-2"
22844,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.117647059,"the, sars-cov-2, and, to, of, is"
22845,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.117647059,"sars-cov, and, to, the, of, with"
22846,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.117647059,"the, of, sars-cov, and"
22847,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.117647059,"of, sars-cov-2, and, with"
22848,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.117647059,"of, is, the, and"
22849,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.117647059,"of, the, identity, with"
22850,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.117647059,"analysis, of, the, virus, with, and"
22851,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.117647059,"analysis, the, bat-sl-cov-2, and"
22852,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.117647059,"the, from, and, further"
22853,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.117647059,"recombination, the, from, transmission"
22854,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.117647059,"in, we, that, the"
22855,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.117647059,"of, in, and, the"
22856,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.117647059,"we, of, sars-cov-2, and"
22857,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.117647059,"the, a, and, in"
22858,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.117647059,"of, a, reservoir, bats"
22859,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.117647059,"have, reservoir, a, are, studies, and"
22860,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.117647059,"the, of, and, sars-cov"
22861,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.117647059,"is, with, and, the"
22862,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.117647059,"sars-cov-2, the, pangolin-cov, and"
22863,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.117647059,"the, sars-cov-2, with, and"
22864,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.117647059,"sars-cov-2, the, for, and"
22865,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.117647059,"sars-cov-2, and, similarity, the"
22866,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.117647059,"to, sars-cov-2, in, and"
22867,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.117647059,"to, the, residues, pangolin-cov"
22868,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.117647059,"in, the, of, pangolin, that, for"
22869,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.117647059,"might, the, of, and"
22870,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.117647059,"to, with, the, of, and, virus"
22871,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.117647059,"to, of, the, virus, has, and"
22872,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.117647059,"the, of, to, identity, that, from"
22873,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.117647059,"to, of, the, bats, was, transmitted"
22874,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.117647059,"the, from, to, identity"
22875,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.117647059,"the, of, sars-cov-2, to, that, not"
22876,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.117647059,"virus, the, to, cov, that, sars-cov-2"
22877,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.117647059,"at, cov, is, the, sars-cov-2, that"
22878,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.117647059,"to, that, sars-cov-2, the, virus, of"
22879,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.117647059,"that, pangolin-cov, the, of, pangolin, to"
22880,Coronaviruses account for over 30% of the world’s viruses.,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.117647059,"for, the"
22881,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.117647059,"this, sars-cov-2, pangolin, the"
22882,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.117647059,"this, of, to, the, that, virus"
22883,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.117647059,"the, of, to, sars-cov-2, that, virus"
22884,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.117647059,"a, with, the, of, virus, from"
22885,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.117647059,"recombination, the, transmission, from"
22886,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.117647059,"the, residues, to, pangolin-cov"
22887,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.117647059,"that, bat, as, the"
22888,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.117647059,"the, as, those, in"
22889,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.117647059,"very, to, that, sars-cov-2"
22890,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.117647059,"that, they, the, of"
22891,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.117647059,"suggested, the, be, of, another, and"
22892,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.117647059,"bat, the, of, another, sars-cov-2, and"
22893,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.117647059,"might, and, the, of"
22894,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.117647059,"and, the, virus, a"
22895,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.117647059,"a, the, be, sars-cov-2"
22896,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.117647059,"might, be, the, sars-cov-2"
22897,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.117647059,"that, the, virus, in, at, a"
22898,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.117647059,"the, of, populations, a, that, this, in, for, virus, is"
22899,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.117647059,"in, that, the, covid-19, be, sars-cov-2"
22900,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.117647059,"sars-cov-2, a, that, the, pandemic, for"
22901,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.117647059,"the, of, and, is, an, to"
22902,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.117647059,"is, and, it, of, to, an"
22903,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.117647059,"with, the, of, natural, it, and"
22904,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.117647059,"a, identified, from, sars-cov-2"
22905,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.117647059,"of, coronaviruses, from, bat"
22906,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.117647059,"a, coronaviruses, in, recent, sars-cov-2, bat"
22907,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.117647059,"in, a, study, of"
22908,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.117647059,"to, sars-cov-2, a, of, in, that, events, with"
22909,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.117647059,"that, were, to, sars-cov-2, found, in"
22910,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.117647059,"a, origin, of, sars-cov-2, patients, in"
22911,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.117647059,"that, was, the, of, sars-cov-2, to"
22912,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.117647059,"to, the, that, a, of, natural"
22913,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.117647059,"that, in, a, naturally, animal, to"
22914,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.117647059,"naturally, furin, cleavage, in, of, such"
22915,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.117647059,",, the, amino, of, that, indicating"
22916,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.117647059,"the, of, that, were, to, in, is, likely"
22917,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.117647059,"bats, were, found, to, related, that, are, hosts"
22918,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.117647059,"in, amino, acid, of"
22919,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.117647059,"coronaviruses, are, in, a, but, of"
22920,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.117647059,"the, has, a, of, to, that, and, bat"
22921,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.117647059,"are, in, but, to, of, the, has, and"
22922,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.117647059,"and, related, to, bat, in, viruses"
22923,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.117647059,"viruses, and, of, bat, that, to"
22924,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.117647059,"of, coronaviruses, from, pangolins, and, sars-cov-2"
22925,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.117647059,"of, sars-cov-2, pangolins, (manis, from, and"
22926,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.117647059,"the, of, pangolin-cov, to, that, pangolin"
22927,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.117647059,"the, of, more, than, is, to"
22928,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.117647059,"closely, related, to, more, than, the"
22929,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.117647059,"based, on, the, analysis, of, and, sars-cov-2, to"
22930,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.117647059,"ace2, and, virus, with, the, in, of, animals."
22931,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.117647059,"the, of, very, to, bat, and"
22932,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.117647059,"the, and, similarity, sars-cov-2"
22933,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.117647059,"the, that, is, a"
22934,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.117647059,"analysis, that, is, the"
22935,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.117647059,"that, or, the, sars-cov-2"
22936,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.117021277,"the, sars-cov-2, and, which, have, to, a, of, in, human, via"
22937,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.117021277,"sars-cov-2, of, which, to, human, via, a, have, in, and, the"
22938,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.117021277,"the, viruses, known, have, are, more, most, than, of, and, any"
22939,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.117021277,"a, of, to, the, from, this, bat, two, coronaviruses,, at, viruses"
22940,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.117021277,"the, huanan, and, that, in, sars-cov-2, animal, likely, than, at, market"
22941,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.117021277,"are, the, most, have, known, of, and, more, viruses, than, any"
22942,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.117021277,"the, was, to, a, virus, that, with, bat, as, and, coronavirus"
22943,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.117021277,"this, that, had, the, virus, than, or, cases, of, in, to"
22944,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.117021277,"this, of, cases, to, the, than, in, that, had, virus, or"
22945,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.117021277,"a, viruses, at, two, to, bat, coronaviruses,, the, of, from, this"
22946,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.117021277,"the, virus, was, as, a, coronavirus, that, with, bat, and, to"
22947,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.117021277,"the, sars-cov-2, animal, at, huanan, market, likely, than, that, in, and"
22948,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.116883117,"sars-cov, from, into, and, to, the, of, may, have"
22949,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.116883117,"a, of, exist, in, and, to, which, the, new"
22950,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.116883117,"a, the, recombination, of, is, and, be, in, to"
22951,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.116883117,"the, and, to, be, a, of, is, in, recombination"
22952,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.116883117,"a, the, from, that, and, are, at, in, humans"
22953,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.116883117,"in, as, an, host, a, found, from, to, and"
22954,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.116883117,"in, the, a, that, are, from, humans, at, and"
22955,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.116883117,"the, virus, for, covid-19, a, of, to, that, from"
22956,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.116883117,"of, that, the, covid-19, is, a, from, as, for"
22957,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.116883117,"that, have, a, of, virus, to, are, the, for"
22958,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.116883117,"the, was, not, to, have, that, in, of, animals"
22959,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.116883117,"a, of, to, the, virus, that, covid-19, from, for"
22960,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.116883117,"and, from, to, the, market, in, its, a, was"
22961,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.116883117,"the, of, also, to, closely, related, bats, in, is"
22962,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.116883117,"the, of, china, a, in, and, virus, sars-cov, isolated"
22963,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.116883117,"from, in, were, that, the, of, coronavirus, likely, hosts"
22964,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.116883117,"sars-cov-2, be, of, natural, the, emergence, and, to, rbd"
22965,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.116883117,"the, and, has, a, in, to, that, coronaviruses, of"
22966,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.116883117,"the, of, in, is, also, closely, related, to, bats"
22967,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.116883117,"the, of, to, is, likely, natural, on, a, that"
22968,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.116883117,"that, by, a, of, virus, similar, to, the, for"
22969,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.116883117,"from, an, host, to, a, as, and, found, in"
22970,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.116883117,"its, and, the, was, from, to, a, market, in"
22971,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.116883117,"al., that, by, a, of, and, the, for, sars-cov-2"
22972,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.116883117,"of, which, to, a, exist, in, and, new, the"
22973,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.116883117,"the, of, on, is, likely, natural, a, to, that"
22974,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.116883117,"in, the, to, that, sars-cov-2, is, of, shows, pangolin"
22975,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.116883117,"the, of, in, receptor, spike, and, backbone, that, a"
22976,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.116883117,"a, of, the, that, covid-19, is, from, for, as"
22977,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.116883117,"that, the, of, in, was, to, animals, not, have"
22978,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.116883117,"a, and, sars-cov, the, of, virus, isolated, in, china"
22979,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.116883117,"to, have, the, of, and, sars-cov, into, may, from"
22980,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.116883117,"with, the, that, sars-cov-2, is, of, are, as, they"
22981,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.116883117,"to, this, that, sars-cov-2, the, complete, be, origin, of"
22982,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.116883117,"a, of, to, have, the, are, virus, that, for"
22983,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.116883117,"the, of, by, for, a, virus, similar, to, that"
22984,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.116883117,"and, the, that, for, of, sars-cov-2, a, by, al."
22985,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.116883117,"the, of, that, spike, in, a, backbone, receptor, and"
22986,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.116883117,"pangolin, to, sars-cov-2, in, the, shows, that, is, of"
22987,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.116883117,"the, that, are, with, of, sars-cov-2, is, they, as"
22988,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.116883117,"that, the, complete, sars-cov-2, to, be, this, of, origin"
22989,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.116883117,"in, the, of, coronavirus, from, that, were, likely, hosts"
22990,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.116883117,"to, a, of, in, the, and, has, that, coronaviruses"
22991,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.116883117,"and, the, of, rbd, to, be, emergence, sars-cov-2, natural"
22992,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.116666667,"coronaviruses, in, which, are, to, sars-cov-2, and"
22993,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.116666667,"to, the, and, palm, civet, may, sars-cov"
22994,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.116666667,"that, have, been, of, to, the, sars-cov-2"
22995,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.116666667,"the, to, sars-cov-2, in, of, a, bat"
22996,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.116666667,"bat, to, genetic, is, which, sars-cov-2, the"
22997,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.116666667,"of, to, a, which, bat, found, in"
22998,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.116666667,"a, sequence, sars-cov-2, the, virus, from, in"
22999,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.116666667,"no, by, in, initial, the, sars-cov-2, is"
23000,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.116666667,"these, and, the, of, to, that, emergence"
23001,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.116666667,"to, sars-cov-2, a, of, the, it, that"
23002,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.116666667,"the, of, is, and, in, with, to"
23003,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.116666667,"humans, the, of, that, sars-cov-2, have, to"
23004,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.116666667,"a, of, in, bats, the, has, that"
23005,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.116666667,"with, the, and, is, to, in, of"
23006,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.116666667,"to, the, that, as, a, of, into"
23007,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.116666667,"the, that, are, to, be, and, of"
23008,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.116666667,"is, with, a, and, of, the, in"
23009,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.116666667,"development, to, the, for, in, and, of"
23010,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.116666667,"a, of, in, their, and, to, the"
23011,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.116666667,"the, also, that, bats, are, for, virus"
23012,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.116666667,"and, sars-cov-2, with, bat, that, the, is"
23013,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.116666667,"a, was, that, the, and, for, to"
23014,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.116666667,"in, to, sars-cov-2, from, and, as, an"
23015,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.116666667,"and, are, bat, a, between, species, in"
23016,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.116666667,"a, as, the, of, that, to, into"
23017,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.116666667,"the, coronavirus, have, of, and, that, these"
23018,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.116666667,"of, the, early, in, that, which, by"
23019,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.116666667,"are, the, of, and, be, that, to"
23020,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.116666667,"a, the, of, is, and, in, with"
23021,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.116666667,"in, 2021, a, joint, and, to, the"
23022,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.116666667,"the, of, to, that, have, humans, sars-cov-2"
23023,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.116666667,"from, is, to, in, that, it, not"
23024,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.116666667,"to, that, sars-cov-2, the, but, of, we"
23025,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.116666667,"still, a, the, that, sars-cov-2, but, pandemic"
23026,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.116666667,"to, a, the, and, has, that, with"
23027,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.116666667,"the, of, as, intermediate, host, was, to"
23028,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.116666667,"is, and, from, to, which, that, coronavirus"
23029,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.116666667,"a, of, the, coronavirus, with, bat, that"
23030,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.116666667,"of, from, to, humans, with, sars-cov-2, the"
23031,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.116666667,"the, is, in, virus, similar, to, that"
23032,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.116666667,"to, the, and, sars-cov, may, palm, civet"
23033,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.116666667,"a, it, the, and, for, is, sars-cov"
23034,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.116666667,"that, bats, to, is, sars-cov-2, analysis, the"
23035,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.116666667,"the, a, of, with, that, coronavirus, bat"
23036,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.116666667,"the, a, was, that, to, and, for"
23037,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.116666667,"a, for, the, sars-cov, is, and, it"
23038,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.116666667,"to, sars-cov-2, the, that, for, ace2, is"
23039,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.116666667,"the, that, also, sars-cov-2, is, it, for"
23040,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.116666667,"the, genome, of, coronavirus, to, bat, more"
23041,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.116666667,"similarity, sars-cov-2, and, bat, cov, the, that"
23042,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.116666667,"similarity, to, sars-cov-2, the, that, is, of"
23043,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.116666667,"the, when, a, virus, from, humans, to"
23044,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.116666667,"to, could, from, in, the, and, been"
23045,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.116666667,"of, that, very, close, to, and, more"
23046,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.116666667,"the, of, human, covid-19, with, and, in"
23047,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.116666667,"the, genome, of, coronavirus, more, to, bat"
23048,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.116666667,"very, close, and, more, that, of, to"
23049,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.116666667,"the, was, from, and, to, of, wuhan"
23050,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.116666667,"a, by, et, genome, from, that, the"
23051,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.116666667,"that, from, to, humans, a, in, the"
23052,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.116666667,"the, indicated, that, in, a, and, to"
23053,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.116666667,"sars-cov-2, from, a, the, virus, sequence, in"
23054,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.116666667,"sars-cov-2, a, the, of, virus, genome, from"
23055,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.116666667,"in, a, with, and, sars-cov-2, the, genome"
23056,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.116666667,"a, in, with, sars-cov-2, the, bat, and"
23057,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.116666667,"and, a, of, between, sars-cov-2, in, the"
23058,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.116666667,"in, the, analysis, of, sequence, that, pangolin"
23059,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.116666667,"a, bat, of, genome, sequences, the, in"
23060,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.116666667,"which, is, to, that, and, coronavirus, from"
23061,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.116666667,"96.2%, sequence, bat, that, and, sars-cov-2, a"
23062,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.116666667,"similarity, be-, tween, sars-cov-2, and, the, that"
23063,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.116666667,"to, the, been, of, and, that, a"
23064,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.116666667,"the, sars-cov-2, to, a, of, in, bat"
23065,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.116666667,"since, at, the, be, that, spillover, of"
23066,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.116666667,"analysis, sequence, in, the, of, pangolin, that"
23067,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.116666667,"the, evolution, of, to, human, and, a"
23068,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.116666667,"a, to, genomic, recent, these, the, and"
23069,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.116666667,"for, the, of, and, in, development, to"
23070,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.116666667,"the, related, is, in, wiv, to, that"
23071,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.116666667,"into, to, not, the, that, sars-cov-2, in"
23072,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.116666667,"the, evolution, of, human, to, a, and"
23073,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.116666667,"to, humans, from, with, the, of, sars-cov-2"
23074,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.116666667,"analysis, that, sars-cov-2, is, to, bats, the"
23075,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.116666667,"that, the, from, a, in, to, humans"
23076,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.116666667,"that, to, sars-cov-2, found, in, bats, from"
23077,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.116666667,"analysis, that, sars-cov-2, the, with, of, to"
23078,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.116666667,"to, the, of, from, transmission, a, with"
23079,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.116666667,"the, virus, from, nucleotide, human, with, to"
23080,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.116666667,"sars-cov-2, from, an, to, as, and, in"
23081,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.116666667,"is, to, the, ratg13, by, from, and"
23082,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.116666667,"the, and, of, that, these, to, emergence"
23083,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.116666667,"the, is, that, to, of, and, it"
23084,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.116666667,"the, natural, is, and, it, to, of"
23085,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.116666667,"the, of, with, a, and, sars-cov-2, or"
23086,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.116666667,"the, with, sars-cov-2, that, hosts, for, than"
23087,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.116666667,"that, with, the, may, potential, to, intermediate"
23088,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.116666667,"the, have, been, isolated, in, obtained, and"
23089,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.116666667,"found, that, the, suggesting, may, have, to"
23090,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.116666667,"the, intermediate, host, from, a, as, to"
23091,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.116666667,"that, the, of, sars-cov-2, to, a, it"
23092,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.116666667,"in, the, of, that, has, a, bats"
23093,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.116666667,"the, a, that, has, with, and, to"
23094,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.116666667,"the, could, been, from, in, to, and"
23095,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.116666667,"the, of, to, and, originate, in, bats"
23096,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.116666667,"that, sars-cov-2, from, a, to, it, in"
23097,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.116666667,"genome, a, sars-cov-2, the, of, virus, from"
23098,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.116666667,"bats, are, the, of, and, in, china"
23099,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.116666667,"a, are, between, and, in, bat, species"
23100,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.116666667,"bats, which, the, cave, can, infected, of, are, to, as, and, in, other, also"
23101,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.116666667,"the, sars-cov-2, which, to, genetic, is, bat"
23102,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.116666667,"the, joint, in, 2021, a, to, and"
23103,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.116666667,"genome, a, sars-cov-2, and, with, the, in"
23104,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.116666667,"the, virus, is, similar, to, that, in"
23105,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.116666667,"the, wiv, that, is, in, related, to"
23106,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.116666667,"cleavage, site, in, a, furin, to, animal"
23107,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.116666667,"a, sars-cov-2, and, with, the, bat, in"
23108,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.116666667,"recent, the, to, a, and, genomic, these"
23109,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.116666667,"the, of, from, wuhan, was, to, and"
23110,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.116666667,"in, a, of, to, survey, the, tested, positive, for, had, sars, closely, related, virus"
23111,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.116666667,"the, virus, from, to, nucleotide, with, human"
23112,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.116666667,"the, a, from, intermediate, host, as, to"
23113,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.116666667,"the, intermediate, host, was, to, of, as"
23114,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.116666667,"when, a, virus, from, to, humans, the"
23115,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.116666667,"intermediate, as, and, genetically, it, multiple, to, for, by, the, of, that, in, a"
23116,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.116666667,"a, survey, of, in, tested, positive, for, sars, had, the, to, virus, closely, related"
23117,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.116666667,"and, at, the, would, that, its, was, for, of, in, this, from, a, by"
23118,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.116666667,"to, the, of, and, suggesting, a, covid-19"
23119,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.116666667,"human, and, with, the, covid-19, in, of"
23120,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.116666667,"since, the, spillover, that, be, at, of"
23121,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.116666667,"from, the, was, for, a, that, this, and, would, by, in, of, at, its"
23122,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.116666667,"that, from, bats, to, found, in, sars-cov-2"
23123,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.116666667,"a, the, of, and, in, their, to"
23124,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.116666667,"that, not, it, to, from, is, in"
23125,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.116666667,"that, the, sars-cov-2, ace2, for, to, is"
23126,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.116666667,"the, similarity, sars-cov-2, of, is, to, that"
23127,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.116666667,"sars-cov-2, a, of, and, the, with, or"
23128,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.116666667,"indicated, that, the, a, in, to, and"
23129,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.116666667,"to, of, in, bats, the, and, originate"
23130,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.116666667,"of, the, by, that, early, in, which"
23131,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.116666667,"of, the, and, similar, to, virus, analysis"
23132,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.116666667,"these, and, that, have, the, coronavirus, of"
23133,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.116666667,"the, that, to, a, of, and, been"
23134,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.116666667,"the, covid-19, and, of, suggesting, a, to"
23135,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.116666667,"the, are, of, bats, in, and, china"
23136,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.116666667,"to, of, from, then, transmission, a, virus"
23137,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.116666667,"and, the, of, infected, also, to, are, as, bats, cave, other, in, which, can"
23138,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.116666667,"been, in, the, isolated, and, have, obtained"
23139,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.116666667,"the, from, that, to, a, bat, and"
23140,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.116666667,"sars-cov-2, a, sequence, and, bat, 96.2%, that"
23141,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.116666667,"to, sars-cov-2, from, a, in, it, that"
23142,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.116666667,"into, the, that, not, in, to, sars-cov-2"
23143,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.116666667,"by, the, of, a, genetically, in, multiple, to, that, as, intermediate, and, it, for"
23144,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.116666667,"it, that, the, sars-cov-2, also, for, is"
23145,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.116666667,"is, sars-cov-2, by, no, the, in, initial"
23146,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.116666667,"and, sars-cov-2, are, to, coronaviruses, in, which"
23147,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.116666667,"of, that, sars-cov-2, are, more, to, ratg13"
23148,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.116666667,"the, and, from, is, to, by, ratg13"
23149,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.116666667,"and, between, ratg13, is, an, the, to"
23150,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.116666667,"the, a, that, from, to, bat, and"
23151,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.116666667,"bats, are, also, for, the, virus, that"
23152,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.116666667,"the, genome, by, et, that, from, a"
23153,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.116666667,"to, the, of, from, by, a, virus"
23154,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.116666667,"the, genome, of, bat, sequences, a, in"
23155,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.116666667,"which, to, a, of, found, in, bat"
23156,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.116666667,"a, between, sars-cov-2, and, the, of, in"
23157,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.116666667,"is, to, the, ratg13, an, between, and"
23158,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.116666667,"sars-cov-2, the, of, that, have, been, to"
23159,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.116666667,"that, hosts, for, sars-cov-2, than, the, with"
23160,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.116666667,"that, the, similarity, be-, tween, sars-cov-2, and"
23161,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.116666667,"the, sars-cov-2, with, that, and, is, bat"
23162,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.116666667,"are, more, to, that, of, sars-cov-2, ratg13"
23163,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.116666667,"that, of, to, with, sars-cov-2, analysis, the"
23164,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.116666667,"to, sars-cov-2, from, of, bats, the, that"
23165,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.116666667,"that, the, of, sars-cov-2, but, we, to"
23166,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.116666667,"transmission, of, from, to, a, with, the"
23167,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.116666667,"a, virus, transmission, from, to, of, then"
23168,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.116666667,"a, by, from, the, virus, to, of"
23169,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.116666667,"that, a, the, sars-cov-2, pandemic, but, still"
23170,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.116666667,"and, the, of, to, it, is, natural"
23171,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.116666667,"to, a, furin, cleavage, site, in, animal"
23172,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.116666667,"that, may, potential, intermediate, to, the, with"
23173,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.116666667,"found, the, to, suggesting, that, may, have"
23174,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.116666667,"analysis, of, virus, similar, to, the, and"
23175,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.116504854,"the, animals, from, that, palm, civets, for, as, virus, to, species, and"
23176,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.116504854,"a, of, to, the, from, which, for, coronavirus, bat, and, genome, virus"
23177,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.116504854,"animals, from, as, that, virus, to, for, and, the, species, palm, civets"
23178,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.116504854,"the, virus, for, a, genome, of, which, to, coronavirus, from, and, bat"
23179,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.116504854,"that, bats, are, the, reservoir, of, and, viruses, in, southern, for, markets"
23180,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.116504854,"the, as, a, of, that, most, likely, bats,, to, infected, by, and"
23181,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.116504854,"in, a, of, for, sars-cov-2, were, to, be, infected, with, suggesting, that"
23182,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.116504854,"the, are, in, markets, for, of, reservoir, viruses, southern, that, bats, and"
23183,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.116504854,"the, to, a, of, as, bats,, most, likely, that, infected, by, and"
23184,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.116504854,"with, for, of, suggesting, a, to, that, were, in, sars-cov-2, be, infected"
23185,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.11627907,"are, and, to, a, in"
23186,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.11627907,"are, in, viruses, a, pangolin"
23187,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.11627907,"a, bat, in, coronaviruses, sars-cov-2"
23188,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.11627907,"from, the, and, this, virus"
23189,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.11627907,"bats, are, the, as, viruses"
23190,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.11627907,"of, the, three, most, identified"
23191,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.11627907,"to, the, bats, be, of"
23192,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.11627907,"genetic, have, to, coronaviruses, sequences"
23193,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.11627907,"bats, of, and, more, than"
23194,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.11627907,"of, to, than, in, which"
23195,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.11627907,"in, of, to, sars-cov-2, which"
23196,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.11627907,"more, species, of, bats, and"
23197,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.11627907,"with, bat, and, into, the"
23198,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.11627907,"t, been, that, of, by"
23199,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.11627907,"of, that, sars-cov-2, a, been"
23200,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.11627907,"coronaviruses, have, genetic, sequences, to"
23201,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.11627907,"the, that, any, to, sars-cov-2"
23202,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.11627907,"that, sars-cov-2, was, the, before"
23203,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.11627907,"groups, that, to, bat, the"
23204,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.11627907,"these, human, viruses, to, the"
23205,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.11627907,"the, groups, bat, that, to"
23206,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.11627907,"the, that, genome, as, to"
23207,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.11627907,"to, sars-cov-2, that, the, as"
23208,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.11627907,"genome, with, bat, that, sars-cov-2"
23209,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.11627907,"the, genome, that, sars-cov-2, a"
23210,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.11627907,"the, was, that, a, of"
23211,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.11627907,"the, sequence, that, sars-cov-2, to"
23212,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.11627907,"the, and, identity, bat, human"
23213,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.11627907,"the, genome, that, was, to"
23214,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.11627907,"analysis, that, protein, in, of"
23215,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.11627907,"compared, with, the, of, is"
23216,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.11627907,"the, sars-cov-2, to, bat, and"
23217,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.11627907,"that, sars-cov-2, animal, origin, and"
23218,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.11627907,"the, in, that, a, of"
23219,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.11627907,"that, the, in, bats, of"
23220,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.11627907,"that, the, of, has, bats"
23221,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.11627907,"that, has, the, scale, of"
23222,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.11627907,"the, as, are, viruses, bats"
23223,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.11627907,"and, bats, of, more, than"
23224,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.11627907,"bats, are, the, most, as"
23225,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.11627907,"to, the, of, sars-cov-2, from"
23226,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.11627907,"the, bats, hosts, for, sars-cov-2"
23227,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.11627907,"however,, the, and, only, in"
23228,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.11627907,"the, of, in, wuhan, china"
23229,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.11627907,"to, the, that, of, origin"
23230,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.11627907,"the, market, that, to, of"
23231,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.11627907,"in, that, the, to, market"
23232,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.11627907,"of, to, suggested, that, the"
23233,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.11627907,"animal, infected, the, of, is"
23234,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.11627907,"to, the, in, zoonotic, of"
23235,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.11627907,"the, market, that, of, in"
23236,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.11627907,"number, of, in, to, the"
23237,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.11627907,"t, that, of, been, by"
23238,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.11627907,"of, and, the, bats, may"
23239,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.11627907,"the, sars-cov, and, to, animals"
23240,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.11627907,"the, was, from, to, in"
23241,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.11627907,"a, the, sars-cov-2, to, is"
23242,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.11627907,"the, sars-cov-2, sequence, is, to"
23243,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.11627907,"from, a, is, to, the"
23244,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.11627907,"from, bats,, sars-cov-2, isolated, with"
23245,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.11627907,"to, sars-cov-2,, and, the, which"
23246,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.11627907,"animals, to, sars-cov, and, the"
23247,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.11627907,"sars-cov, the, from, in, china"
23248,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.11627907,"protein, analysis, that, of, in"
23249,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.11627907,"of, is, that, in, bat"
23250,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.11627907,"is, that, the, and, sars-cov-2"
23251,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.11627907,"genome, the, bat, of, and"
23252,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.11627907,"of, the, that, bats, reservoirs"
23253,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.11627907,"are, the, that, bats, for"
23254,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.11627907,"and, to, the, of, sars-cov-2"
23255,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.11627907,"this, is, of, the, in"
23256,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.11627907,"is, evidence, in, from, to"
23257,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.11627907,"in, this, be, the, of"
23258,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.11627907,"the, in, a, zoonotic, and"
23259,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.11627907,"by, and, in, the, origin"
23260,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.11627907,"origin, the, that, by, and"
23261,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.11627907,"in, a, origin, that, zoonotic"
23262,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.11627907,"a, virus, that, was, the"
23263,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.11627907,"the, that, a, virus, been"
23264,"bats are also important reservoir species for a great 

range of coronaviruses","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.11627907,"are, reservoir, species, a, coronaviruses"
23265,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.11627907,"the, of, that, to, origin"
23266,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.11627907,"genomic, that, sars-cov-2, could, the"
23267,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.11627907,"studies, that, the, and, spread"
23268,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.11627907,"genomic, that, the, and, through"
23269,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.11627907,"that, sars-cov-2, has, the, and"
23270,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.11627907,"of, at, the, was, from"
23271,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.11627907,"the, at, was, that, and"
23272,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.11627907,"have, that, they, of, and"
23273,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.11627907,"that, the, of, bat, coronavirus"
23274,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.11627907,"the, from, phylogenetic, that, and"
23275,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.11627907,"from, of, bats, sars-cov-2, and"
23276,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.11627907,"from, of, to, sars-cov-2, the"
23277,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.11627907,"this, the, that, are, sars-cov-2"
23278,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.11627907,"that, the, sars-cov-2, bat, viruses"
23279,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.11627907,"in, viruses, are, into, and, sars-cov-2, this, that, the, origin"
23280,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.11627907,"the, from, animals, humans, market"
23281,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.11627907,"the, huanan, market, of, zoonotic"
23282,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.11627907,"the, of, at, sars-cov-2, for"
23283,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.11627907,"the, of, that, to, market"
23284,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.11627907,"the, that, sars-cov-2, to, and"
23285,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.11627907,"that, sars-cov-2, in, animal, humans"
23286,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.11627907,"the, that, to, market, in"
23287,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.11627907,"the, in, of, this, is"
23288,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.11627907,"from, the, was, at, of"
23289,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.11627907,"a, virus, from, was, the"
23290,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.11627907,"the, huanan, market, of, a"
23291,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.11627907,"the, of, at, a, virus"
23292,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.11627907,"the, viruses, these, to, human"
23293,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.11627907,"and, that, the, was, at"
23294,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.11627907,"sars-cov-2, that, and, was, the"
23295,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.11627907,"the, that, sars-cov-2, likely, than"
23296,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.11627907,"were, to, in, and, humans"
23297,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.11627907,"in, a, published, the, of"
23298,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.11627907,"the, that, sars-cov-2, a, in"
23299,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.11627907,"the, identified, of, three, most"
23300,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.11627907,"of, covid-19, cases, the, huanan"
23301,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.11627907,"of, were, to, and, the"
23302,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.11627907,"evidence, that, is, a, or"
23303,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.11627907,"that, to, genome, as, the"
23304,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.11627907,"the, as, in, from, a"
23305,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.11627907,"to, from, evidence, in, is"
23306,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.11627907,"to, in, from, an, a"
23307,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.11627907,"on, the, that, and, a"
23308,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.11627907,"the, to, as, bat, and"
23309,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.11627907,"the, virus, to, as, bat"
23310,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.11627907,"that, the, and, coronavirus, has"
23311,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.11627907,"to, the, a, virus, with"
23312,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.11627907,"and, from, this, the, virus"
23313,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.11627907,"and, that, they, have, of"
23314,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.11627907,"and, of, a, zoonotic, to"
23315,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.11627907,"a, zoonotic, and, that, to"
23316,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.11627907,"that, from, animals, in, and"
23317,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.11627907,"the, of, natural, host, and"
23318,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.11627907,"through, and, to, from, animals"
23319,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.11627907,"is, very, and, to, through"
23320,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.11627907,"the, to, was, a, bat"
23321,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.11627907,"bat, coronavirus, to, the, genome"
23322,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.11627907,"the, of, animal, was, to"
23323,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.11627907,"the, of, to, animal, be"
23324,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.11627907,"of, to, intermediate, animal, be"
23325,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.11627907,"that, a, in, of, with"
23326,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.11627907,"in, to, of, than, which"
23327,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.11627907,"that, market, in, the, virus"
23328,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.11627907,"or, in, close, to, virus"
23329,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.11627907,"of, the, covid-19, cases, huanan"
23330,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.11627907,"huanan, in, the, december, of"
23331,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.11627907,"the, of, in, market, early"
23332,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.11627907,"of, the, clustering, in, with"
23333,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.11627907,"and, the, virus, from, to"
23334,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.11627907,"the, that, of, has, is"
23335,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.11627907,"that, sars-cov-2, to, as, the"
23336,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.11627907,"a, virus, the, was, from"
23337,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.11627907,"the, sars-cov-2, was, that, and"
23338,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.11627907,"the, as, from, a, pangolin"
23339,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Bats have been reported as being the rich source of 

coronaviruses",0.11627907,"the, of, bats, have, as"
23340,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.11627907,"a, sars-cov-2, to, with, coronavirus"
23341,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.11627907,"the, from, infected, to, and"
23342,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.11627907,"the, of, similar, to, sars-cov-2"
23343,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.11627907,"to, of, from, with, sars-cov-2"
23344,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.11627907,"the, of, to, sars-cov-2, from"
23345,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.11627907,"the, of, that, to, suggested"
23346,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.11627907,"the, sars-cov-2, has, to, of"
23347,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.11627907,"the, to, sars-cov-2, of, a"
23348,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.11627907,"to, by, genetic, sars-cov-2, the"
23349,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.11627907,"of, be, the, possible, bat"
23350,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.11627907,"the, animal, was, to, of"
23351,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.11627907,"and, are, to, in, a"
23352,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.11627907,"the, to, was, in, from"
23353,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.11627907,"the, virus, to, and, from"
23354,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.11627907,"the, to, a, virus, in"
23355,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.11627907,"the, and, market, a, to"
23356,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.11627907,"and, from, animals, to, through"
23357,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.11627907,"to, and, in, at, the"
23358,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.11627907,"the, genetic, that, from, virus"
23359,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.11627907,"the, covid-19, of, zoonotic, to"
23360,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.11627907,"to, that, the, most, of"
23361,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.11627907,"that, covid-19, in, to, genetic"
23362,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.11627907,"a, was, that, the, is"
23363,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.11627907,"the, of, virus, is, that"
23364,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.11627907,"the, that, a, virus, evidence"
23365,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.11627907,"were, humans, in, and, to"
23366,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.11627907,"the, virus, to, that, and"
23367,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.11627907,"the, that, virus, to, and"
23368,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.11627907,"the, natural, to, virus, in"
23369,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.11627907,"the, and, natural, origin, to"
23370,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.11627907,"and, in, the, that, to"
23371,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.11627907,"the, that, more, likely, to"
23372,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.11627907,"to, the, in, and, that"
23373,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.11627907,"of, in, december, the, huanan"
23374,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.11627907,"in, of, reported, and, the"
23375,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.11627907,"reported, the, was, and, in"
23376,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.11627907,"the, of, in, was, outbreak"
23377,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.11627907,"with, the, and, into, bat"
23378,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.11627907,"that, the, and, to, is"
23379,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.11627907,"is, to, the, that, may"
23380,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.11627907,"the, in, however,, only, and"
23381,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.11627907,"revealed, that, the, to, bat"
23382,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.11627907,"to, the, be, possible, bat"
23383,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.11627907,"that, genomic, the, sars-cov-2, bat"
23384,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.11627907,"the, market, in, that, virus"
23385,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.11627907,"in, it, that, the, first"
23386,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.11627907,"that, may, have, in, or"
23387,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.11627907,"the, be, of, possible, bat"
23388,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.11627907,"to, the, a, sars-cov-2, is"
23389,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.11627907,"is, that, the, was, a"
23390,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.11627907,"is, that, the, and, to"
23391,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.11627907,"the, that, which, was, by"
23392,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.11627907,"the, of, is, to, sars-cov"
23393,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.11627907,"has, the, of, from, bat"
23394,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.11627907,"the, that, has, been, from"
23395,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.11627907,"to, the, sequence, sars-cov-2, is"
23396,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.11627907,"genome, to, the, of, virus"
23397,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.11627907,"of, bat, genome, similarity, sars-cov-2"
23398,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.11627907,"that, may, have, to, sars-cov-2"
23399,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.11627907,"are, pangolin, in, a, viruses"
23400,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.11627907,"the, in, a, as, from"
23401,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.11627907,"a, from, the, pangolin, as"
23402,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.11627907,"the, of, are, a, pangolin"
23403,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.11627907,"is, that, from, a, virus"
23404,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.11627907,"is, that, a, virus, from"
23405,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.11627907,"a, is, an, to, human"
23406,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.11627907,"the, a, for, it, from"
23407,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.11627907,"bat, the, sars-cov-2, bats, are"
23408,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.11627907,"the, in, bats, to, from"
23409,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.11627907,"in, to, the, also, from"
23410,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.11627907,"to, of, is, related, in"
23411,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.11627907,"infected, to, from, and, the"
23412,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.11627907,"to, the, from, then, virus"
23413,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.11627907,"origin, that, and, animal, sars-cov-2"
23414,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.11627907,"a, that, sars-cov-2, and, is"
23415,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.11627907,"a, is, suggests, that, not"
23416,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.11627907,"is, and, very, to, through"
23417,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.11627907,"intermediate, animal, to, be, of"
23418,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.11627907,"animal, species, to, sars-cov-2, and"
23419,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.11627907,"of, sars-cov-2, is, and, to"
23420,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.11627907,"between, and, that, of, sars-cov-2"
23421,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.11627907,"the, of, to, that, and"
23422,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.11627907,"the, coronavirus, strain, sequence, with"
23423,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.11627907,"the, of, and, detected, in"
23424,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.11627907,"the, of, genome, virus, to"
23425,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.11627907,"the, to, sequence, that, sars-cov-2"
23426,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.11627907,"results, that, of, sars-cov-2, the"
23427,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.11627907,"the, of, sars-cov-2, to, is"
23428,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.11627907,"to, that, sars-cov-2, the, of"
23429,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.11627907,"the, bat, and, identity, human"
23430,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.11627907,"the, genome, was, to, bat"
23431,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.11627907,"revealed, that, to, bat, the"
23432,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.11627907,"the, of, virus, to, bat"
23433,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.11627907,"that, the, genome, sars-cov-2, a"
23434,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.11627907,"on, the, a, that, and"
23435,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.11627907,"et, revealed, that, the, and"
23436,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.11627907,"by, and, genome, the, sars-cov-2"
23437,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.11627907,"that, sars-cov-2, not, from, a"
23438,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.11627907,"the, that, sars-cov-2, not, from"
23439,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.11627907,"the, et, revealed, that, and"
23440,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.11627907,"et, al., bat, at, the"
23441,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.11627907,"that, the, (ratg13), at, and"
23442,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.11627907,"studies, that, and, spread, the"
23443,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.11627907,"the, a, that, and, to"
23444,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.11627907,"that, in, animals, and, from"
23445,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.11627907,"the, to, a, from, animals"
23446,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.11627907,"that, from, a, to, in"
23447,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.11627907,"the, to, that, transmitted, from"
23448,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.11627907,"the, of, infected, animal, is"
23449,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.11627907,"a, that, was, and, in"
23450,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.11627907,"in, market, that, was, at"
23451,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.11627907,"genomic, that, the, to, of"
23452,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.11627907,"the, sars-cov, in, from, china"
23453,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.11627907,"a, in, may, sars-cov-2, bat"
23454,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.11627907,"the, that, sars-cov-2, a, and"
23455,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.11627907,"other, and, are, sars-cov-2, the"
23456,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.11627907,"are, other, sars-cov-2, the, and"
23457,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.11627907,"the, of, to, may, be"
23458,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.11627907,"the, of, may, to, intermediate"
23459,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.11627907,"the, sequence, with, coronavirus, strain"
23460,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.11627907,"the, from, which, with, sars-cov-2"
23461,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.11627907,"has, sequence, with, sars-cov-2, a"
23462,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.11627907,"that, the, of, a, after"
23463,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.11627907,"genome, the, was, to, that"
23464,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.11627907,"that, with, the, of, to"
23465,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.11627907,"of, that, the, a, these"
23466,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.11627907,"of, the, infected, with, sars-cov-2"
23467,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.11627907,"the, of, sars-cov-2, with, human"
23468,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.11627907,"the, of, sars-cov-2, to, and"
23469,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.11627907,"of, the, sars-cov-2, lineage, and"
23470,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.11627907,"to, sars-cov-2, the, bats, of"
23471,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.11627907,"in, from, a, an, to"
23472,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.11627907,"the, to, bat, was, a"
23473,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.11627907,"a, of, to, sars-cov-2, the"
23474,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.11627907,"of, sars-cov-2, from, closest, bat"
23475,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.11627907,"in, the, an, of, bat"
23476,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.11627907,"was, that, the, of, a"
23477,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.11627907,"the, sars-cov-2, from, and, as"
23478,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.11627907,"of, and, a, between, the"
23479,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.11627907,"the, from, a, and, of"
23480,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.11627907,"from, pangolins, sars-cov-2, the, of"
23481,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.11627907,"a, of, by, the, china"
23482,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.11627907,"the, of, by, a, virus"
23483,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.11627907,"and, the, detected, in, of"
23484,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.11627907,"and, of, in, bat, populations"
23485,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.11627907,"the, of, to, in, zoonotic"
23486,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.11627907,"the, to, sars-cov-2, in, of"
23487,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.11627907,"the, reservoirs, of, in, and"
23488,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.11627907,"a, from, for, the, it"
23489,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.11627907,"the, sars-cov-2, it, possible, for"
23490,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.11627907,"the, pangolins, with, a, sars-cov-2"
23491,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.11627907,"cov, the, with, sars-cov-2, for"
23492,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.11627907,"a, in, the, sars-cov-2, for"
23493,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.11627907,"to, bat, be, the, possible"
23494,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.11627907,"that, the, of, sars-cov-2, viruses"
23495,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.11627907,"the, genome, by, sars-cov-2, and"
23496,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.11627907,"the, virus, and, to, december"
23497,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.11627907,"sars-cov-2, the, virus, and, to"
23498,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.11627907,"sars-cov-2, the, any, that, to"
23499,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.11627907,"human, with, sars-cov-2, the, of"
23500,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.11627907,"from, the, which, with, sars-cov-2"
23501,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.11627907,"of, from, in, coronaviruses, sars-cov-2"
23502,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.11627907,"that, of, in, with, a"
23503,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.11627907,"similarity, sars-cov-2, bat, that, in"
23504,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.11627907,"genome, in, bat, of, virus"
23505,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.11627907,"in, of, sars-cov-2, that, virus"
23506,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.11627907,"the, has, is, that, of"
23507,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.11627907,"the, is, of, zoonotic, a"
23508,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.11627907,"animal, a, zoonotic, the, that"
23509,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.11627907,"the, sars-cov-2, of, et, to"
23510,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.11627907,"the, in, also, to, from"
23511,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.11627907,"the, sars-cov-2, as, from, and"
23512,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","bats are also important reservoir species for a great 

range of coronaviruses",0.11627907,"reservoir, a, are, coronaviruses, species"
23513,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.11627907,"of, sars-cov-2, and, from, bats"
23514,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.11627907,"of, the, were, to, and"
23515,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.11627907,"in, the, reported, and, of"
23516,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.11627907,"of, the, in, and, sars-cov-2"
23517,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.11627907,"the, sars-cov-, from, with, and"
23518,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.11627907,"s, the, sars-cov-2, ratg13, which"
23519,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.11627907,"the, furin, cleavage, at, s1/s2"
23520,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.11627907,"the, sars-cov-2, with, coronaviruses, be"
23521,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.11627907,"in, the, rbd, pangolin-cov, sars-cov-2"
23522,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.11627907,"a, to, that, the, sars-cov-2"
23523,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.11627907,"in, the, was, reported, and"
23524,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.11627907,"a, that, the, to, and"
23525,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.11627907,"to, sars-cov-2, be, a, the"
23526,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.11627907,"to, be, the, of, may"
23527,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.11627907,"possible, for, sars-cov-2, it, the"
23528,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.11627907,"the, and, sars-cov-2, animal, to"
23529,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.11627907,"the, in, and, to, at"
23530,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.11627907,"and, sars-cov-2, to, animal, species"
23531,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.11627907,"to, in, and, were, animal"
23532,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.11627907,"of, in, the, market, early"
23533,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.11627907,"in, the, outbreak, was, of"
23534,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.11627907,"that, was, in, at, market"
23535,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.11627907,"of, the, in, that, sequences"
23536,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.11627907,"the, of, that, market, in"
23537,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.11627907,"the, sars-cov-2, from, in, of"
23538,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.11627907,"the, sars-cov-2, in, from, of"
23539,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.11627907,"the, of, and, that, from, a, in, evidence, with, to"
23540,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.11627907,"the, natural, reservoir, not, of"
23541,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.11627907,"the, virus, to, a, in"
23542,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.11627907,"the, of, covid-19, to, zoonotic"
23543,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.11627907,"the, of, zoonotic, is, a"
23544,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.11627907,"the, of, closely, a, covid-19"
23545,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.11627907,"more, bats, of, species, and"
23546,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.11627907,"the, in, reservoirs, and, of"
23547,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.11627907,"of, in, reservoirs, and, the"
23548,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.11627907,"the, bats, are, more, likely"
23549,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.11627907,"of, the, animal, as, for"
23550,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.11627907,"the, as, bat, and, to"
23551,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.11627907,"the, of, to, sars-cov-2, bats"
23552,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.11627907,"that, the, in, and, to"
23553,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.11627907,"bat, sars-cov-2, the, in, china"
23554,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.11627907,"that, sars-cov-2, the, and, to"
23555,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.11627907,"virus, to, for, and, the"
23556,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.11627907,"and, the, virus, in, china"
23557,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.11627907,"the, of, to, species, and"
23558,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.11627907,"the, to, appear, in, of"
23559,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.11627907,"genetic, to, that, covid-19, in"
23560,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.11627907,"to, from, with, of, sars-cov-2"
23561,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.11627907,"to, of, from, a, with"
23562,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.11627907,"genetic, to, sars-cov-2, by, the"
23563,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.11627907,"sars-cov-2, bat, similarity, to, the"
23564,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.11627907,"the, sars-cov-2, are, and, other"
23565,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.11627907,"sars-cov-2, was, are, to, and"
23566,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.11627907,"similarity, sars-cov-2, to, the, viruses"
23567,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.11627907,"on, the, by, of, in, virus,, that, through, natural, a"
23568,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.11627907,"the, furin, at, s1/s2, cleavage"
23569,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.11627907,"sars-cov-2,, the, which, to, and"
23570,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.11627907,"viruses, have, a, which, is"
23571,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.11627907,"the, of, sars-cov-2, for, and"
23572,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.11627907,"the, virus, as, bat, to"
23573,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.11627907,"the, virus, to, of, bat"
23574,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.11627907,"virus, in, is, sars-cov-2, the"
23575,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.11627907,"sars-cov-2, may, a, in, bat"
23576,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.11627907,"that, in, the, it, first"
23577,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.11627907,"is, unlikely, that, sars-cov-2, through"
23578,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.11627907,"it, is, that, the, sars-cov-2"
23579,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.11627907,"the, of, a, from, and"
23580,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.11627907,"evidence, to, from, a, of, in, the, and, that, with"
23581,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.11627907,"is, to, the, that, identified, by, researchers, an, and, but"
23582,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.11627907,"the, of, zoonotic, huanan, market"
23583,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.11627907,"of, a, the, huanan, market"
23584,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.11627907,"a, zoonotic, of, to, and"
23585,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.11627907,"and, the, to, a, market"
23586,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.11627907,"the, natural, origin, to, and"
23587,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.11627907,"the, evidence, covid-19, to, and"
23588,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.11627907,"a, zoonotic, that, to, and"
23589,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.11627907,"the, that, animal, zoonotic, a"
23590,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.11627907,"that, natural, the, virus, for"
23591,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","expended to make the simple point 

that COVID-19 had a natural origin.",0.11627907,"that, the, covid-19, a, to"
23592,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","expended to make the simple point 

that COVID-19 had a natural origin.",0.11627907,"natural, the, a, to, that"
23593,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.11627907,"that, sars-cov-2, from, to, in"
23594,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.11627907,"to, that, sars-cov-2, from, bats"
23595,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.11627907,"the, number, of, to, in"
23596,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.11627907,"the, to, in, of, a"
23597,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.11627907,"the, results, to, a, and"
23598,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.11627907,"of, to, a, which, in"
23599,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.11627907,"genomic, that, sars-cov-2, bat, the"
23600,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.11627907,"genomic, that, the, virus, in"
23601,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.11627907,"a, bat, sars-cov-2, the, in"
23602,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.11627907,"that, sars-cov-2, is, likely, to"
23603,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.11627907,"of, sars-cov-2, is, a, that"
23604,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.11627907,"the, have, would, been, of"
23605,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.11627907,"genetic, that, the, virus, from"
23606,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.11627907,"that, the, of, likely, bats"
23607,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.11627907,"that, the, of, similarity, to"
23608,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.11627907,"is, that, the, may, to"
23609,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.11627907,"suggests, that, a, is, not"
23610,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.11627907,"the, of, that, sars-cov-2, jumped"
23611,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.11627907,"that, of, sars-cov-2, jumped, the"
23612,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.11627907,"of, that, the, virus, to"
23613,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.11627907,"that, pangolins, sars-cov-2, in, an"
23614,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.11627907,"this, the, in, that, sars-cov-2"
23615,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.11627907,"we, also, that, the, sars-cov-2"
23616,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.11627907,"the, to, in, rbd, of"
23617,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.11627907,"pangolins, a, sars-cov-2, with, the"
23618,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.11627907,"from, the, and, with, sars-cov-"
23619,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.11627907,"disease, in, is, and, very"
23620,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.",0.11627907,"in, fact,, a, of, with"
23621,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.11627907,"that, the, bat, coronavirus, of"
23622,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.11627907,"the, that, after, a, of"
23623,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.11627907,"the, covid-19, of, a, closely"
23624,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.11627907,"evidence, that, the, virus, a"
23625,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.11627907,"this, a, that, the, covid-19"
23626,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.11627907,"the, of, and, more, bats"
23627,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.11627907,"phylogenetic, and, that, from, the"
23628,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.11627907,"the, covid-19, and, evidence, to"
23629,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.11627907,"is, evidence, that, or, a"
23630,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.11627907,"that, the, a, of, these"
23631,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.11627907,"as, the, animal, for, of"
23632,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.11627907,"in, the, of, that, bats"
23633,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.11627907,"genomic, that, through, and, the"
23634,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.11627907,"to, december, virus, and, the"
23635,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.11627907,"virus, that, genomic, the, in"
23636,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.11627907,"was, that, the, which, by"
23637,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.11627907,"the, of, that, to, bat"
23638,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.11627907,"which, found, in, the, with"
23639,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.11627907,"wuhan, the, in, of, china"
23640,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.11627907,"appear, to, in, the, of"
23641,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.11627907,"been, of, the, would, have"
23642,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.11627907,"no, the, of, natural, is"
23643,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.11627907,"bats, may, the, of, and"
23644,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.11627907,"to, in, virus, or, close"
23645,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.11627907,"the, in, a, of, and"
23646,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.11627907,"sars-cov-2, and, the, lineage, of"
23647,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.11627907,"of, the, sars-cov-2, is, virus"
23648,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.11627907,"of, in, their, which, an"
23649,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.11627907,"in, the, between, and, an"
23650,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.11627907,"a, that, the, and, is"
23651,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.11627907,"the, and, of, is, that"
23652,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.11627907,"the, that, a, this, covid-19"
23653,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.11627907,"the, from, a, animals, to"
23654,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.11627907,"that, sars-cov-2, with, genome, bat"
23655,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.11627907,"a, has, sequence, with, sars-cov-2"
23656,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.11627907,"disease, is, and, very, in"
23657,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.11627907,"on, the, in, and, bats"
23658,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.11627907,"virus, is, sars-cov-2, the, of"
23659,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.11627907,"that, to, sars-cov-2, in, from"
23660,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.11627907,"recent, that, to, sars-cov-2, in"
23661,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.11627907,"through, is, unlikely, that, sars-cov-2"
23662,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.11627907,"compared, with, the, is, of"
23663,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.11627907,"recent, that, sars-cov-2, to, in"
23664,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.11627907,"animal, that, sars-cov-2, humans, in"
23665,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.11627907,"the, origin, and, by, in"
23666,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.11627907,"is, no, of, the, natural"
23667,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.11627907,"was, and, are, to, sars-cov-2"
23668,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.11627907,"and, sars-cov-2, ratg13, viruses, to"
23669,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.11627907,"similarity, sars-cov-2, of, genome, bat"
23670,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.11627907,"the, origin, and, by, that"
23671,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.11627907,"has, been, that, the, from"
23672,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.11627907,"the, is, that, researchers, identified, to, by, and, but, an"
23673,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.11627907,"its, the, of, sars-cov-2, to"
23674,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.11627907,"closest, sars-cov-2, from, of, bat"
23675,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.11627907,"the, of, to, that, most"
23676,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.11627907,"the, of, natural, origin, and"
23677,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.11627907,"the, and, sars-cov-2, to, bat"
23678,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.11627907,"a, and, to, results, the"
23679,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.11627907,"the, likely, are, more, bats"
23680,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.11627907,"et, al., the, bat, at"
23681,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.11627907,"the, sars-cov-2, bat, in, china"
23682,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.11627907,"a, the, sars-cov-2, in, bat"
23683,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.11627907,"the, sars-cov-2, at, of, complete"
23684,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.11627907,"a, of, in, to, which"
23685,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.11627907,"is, an, to, a, human"
23686,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.11627907,"an, in, which, of, their"
23687,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.11627907,"sars-cov-2, viruses, to, ratg13, and"
23688,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.11627907,"in, pangolins, an, that, sars-cov-2"
23689,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.11627907,"have, that, may, to, sars-cov-2"
23690,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.11627907,"the, of, on, by, natural, in, a, virus,, through, that"
23691,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.11627907,"clustering, of, in, the, with"
23692,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.11627907,"the, of, sequences, in, that"
23693,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.11627907,"the, clustering, in, that, sars-cov-2"
23694,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.11627907,"that, the, sars-cov-2, and, viruses"
23695,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.11627907,"the, in, bats, and, on"
23696,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.11627907,"sars-cov-2, are, bat, bats, the"
23697,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.11627907,"for, sars-cov-2, with, the, cov"
23698,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.11627907,"the, of, that, has, bats"
23699,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.11627907,"the, coronavirus, that, has, and"
23700,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.11627907,"the, of, more, and, bats"
23701,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.11627907,"that, bat, in, similarity, sars-cov-2"
23702,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.11627907,"the, viruses, to, sars-cov-2, similarity"
23703,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.11627907,"origin, the, this, that, sars-cov-2, and, are, in, viruses, into"
23704,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.11627907,"are, that, the, sars-cov-2, this"
23705,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.11627907,"the, in, that, sars-cov-2, this"
23706,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.11627907,"ratg13, s, the, which, sars-cov-2"
23707,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.11627907,"viruses, bat, that, the, sars-cov-2"
23708,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.11627907,"the, that, sars-cov-2, we, also"
23709,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.11627907,"the, and, that, sars-cov-2, viruses"
23710,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.11627907,"ratg13, is, the, bat, than"
23711,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.11627907,"that, in, may, have, or"
23712,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.11627907,"the, genome, of, and, bat"
23713,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.11627907,"bat, virus, in, genome, of"
23714,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.11627907,"in, and, the, virus, of"
23715,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.11627907,"the, more, likely, to, that"
23716,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.11627907,"of, that, to, the, bat"
23717,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.11627907,"is, and, of, sars-cov-2, to"
23718,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.11627907,"the, and, to, of, with"
23719,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.11627907,"sars-cov-2, the, and, of, is"
23720,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.11627907,"and, the, of, sars-cov-2, is"
23721,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.11627907,"sars-cov-2, highest, bat-, the, of"
23722,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.11627907,"that, the, and, (ratg13), at"
23723,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.11627907,"the, of, and, that, sars-cov-2"
23724,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.11627907,"of, and, between, in, the"
23725,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.11627907,"with, isolated, from, bats,, sars-cov-2"
23726,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.11627907,"in, the, to, sars-cov-2, and"
23727,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.11627907,"natural, virus, that, the, for"
23728,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.11627907,"in, the, of, virus, and"
23729,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.11627907,"of, sars-cov-2, complete, at, the"
23730,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.11627907,"the, in, of, this, be"
23731,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.11627907,"the, in, an, of, bat"
23732,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.11627907,"between, an, and, the, in"
23733,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.11627907,"to, from, the, of, sars-cov-2"
23734,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.11627907,"that, sars-cov-2, to, bats, the"
23735,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.11627907,"that, the, from, transmitted, to"
23736,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.11627907,"the, bats, to, of, sars-cov-2"
23737,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.11627907,"that, to, sars-cov-2, bats, from"
23738,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.11627907,"to, the, of, rbd, from"
23739,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.11627907,"the, pangolin-cov, rbd, sars-cov-2, in"
23740,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.11627907,"sars-cov-2, the, as, intermediate, for"
23741,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.11627907,"the, of, sars-cov-2, highest, bat-"
23742,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.11627907,"the, virus, a, with, to"
23743,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.11627907,"the, virus, from, to, then"
23744,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.11627907,"the, rbd, of, to, from"
23745,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.11627907,"sars-cov-2, to, is, likely, that"
23746,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.11627907,"the, sars-cov-2, and, of, bat"
23747,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.11627907,"the, an, between, and, be"
23748,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.11627907,"a, that, the, virus, been"
23749,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.11627907,"the, for, of, sars-cov-2, at"
23750,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.11627907,"of, a, virus, at, the"
23751,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.11627907,"the, natural, reservoir, of, not"
23752,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.11627907,"sars-cov-2, bat, coronaviruses, in, a"
23753,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.11627907,"of, coronaviruses, from, in, sars-cov-2"
23754,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.11627907,"origin, a, zoonotic, that, in"
23755,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.11627907,"a, coronavirus, to, with, sars-cov-2"
23756,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.11627907,"the, found, in, with, which"
23757,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.11627907,"the, was, to, that, sars-cov-2"
23758,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.11627907,"that, the, protein, of, to"
23759,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.11627907,"the, in, of, rbd, to"
23760,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.11627907,"the, bat, ratg13, is, than"
23761,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.11627907,"that, is, in, of, bat"
23762,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.11627907,"of, in, is, related, to"
23763,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.11627907,"of, and, in, bat, populations"
23764,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.11627907,"to, the, of, may, intermediate"
23765,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.11627907,"to, that, of, the, protein"
23766,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.11627907,"bat, to, similarity, sars-cov-2, the"
23767,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.115942029,"a, from, in, that, the, group, of, bats"
23768,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.115942029,"to, many, viral, bat, and, which, viruses, other"
23769,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.115942029,"of, to, is, a, in, with, sars-cov-2, the"
23770,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.115942029,"that, the, virus, in, bats, and, to, a"
23771,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.115942029,"the, of, coronavirus, is, to, for, can, be"
23772,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.115942029,"coronaviruses, and, a, novel, to, the, coronavirus, with"
23773,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.115942029,"several, coronaviruses, found, in, are, to, sars-cov-2, and"
23774,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.115942029,"this, we, sars-cov-2, and, the, viruses, that, in"
23775,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.115942029,"bats, a, the, virus, and, in, that, to"
23776,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.115942029,"bats, are, of, infectious, and, which, to, in"
23777,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.115942029,"for, coronavirus, the, of, is, can, be, to"
23778,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.115942029,"the, have, to, animal, in, and, market, virus"
23779,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.115942029,"of, covid-19, with, onset, december, and, the, in"
23780,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.115942029,"of, the, and, with, homology,, in, virus, analysis"
23781,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.115942029,"the, a, novel, coronavirus, coronaviruses, to, and, with"
23782,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.115942029,"to, sars-, the, of, bats, and, as, cov-2,"
23783,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.115942029,"sequence, and, from, bat, as, to, that, coronavirus"
23784,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.115942029,"the, and, that, from, a, in, humans, to"
23785,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.115942029,"spread, from, and, to, the, that, in, a"
23786,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.115942029,"in, a, and, are, similar, to, the, genome"
23787,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.115942029,"are, a, coronaviruses, to, in, the, bat, and"
23788,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.115942029,"sequence, coronavirus, that, from, to, bat, as, and"
23789,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.115942029,"that, bat, species, in, as, can, a, to"
23790,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.115942029,"is, coronavirus, a, sequence, that, can, in, coronaviruses"
23791,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.115942029,"sars-cov-2, ace2, a, of, and, that, the, as"
23792,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.115942029,"on, and, of, in, the, western, huanan, market."
23793,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.115942029,"for, the, of, and, that, a, in, taken"
23794,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.115942029,"and, the, that, was, for, of, in, a"
23795,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.115942029,"and, was, for, the, of, that, in, a"
23796,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.115942029,"the, of, that, in, a, human, and, to"
23797,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.115942029,"a, in, that, the, virus, is, to, of"
23798,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.115942029,"a, of, the, in, is, to, with, sars-cov-2"
23799,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.115942029,"that, the, of, sars-cov-2, and, ace2, as, a"
23800,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.115942029,"to, the, in, and, evidence, that, bats, could"
23801,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.115942029,"and, to, bat, viral, which, many, other, viruses"
23802,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.115942029,"the, of, and, intermediate, species, likely, as, to"
23803,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.115942029,"reservoir, intermediate, as, and, to, the, of, sars-cov-2"
23804,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.115942029,"a, bat, species, can, as, to, that, in"
23805,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.115942029,"viruses, to, the, in, of, that, a, covid-19"
23806,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.115942029,"the, genome, and, a, in, are, similar, to"
23807,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.115942029,"the, and, bat, coronaviruses, a, in, are, to"
23808,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.115942029,"that, the, from, a, in, to, humans, and"
23809,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.115942029,"the, in, and, that, taken, for, a, of"
23810,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.115942029,"the, species, likely, to, as, of, intermediate, and"
23811,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.115942029,"that, the, of, and, suggests, this, likely, from"
23812,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.115942029,"of, to, a, sequence, was, from, found, in"
23813,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.115942029,"of, the, covid-19, in, with, onset, december, and"
23814,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.115942029,"on, in, the, of, and, western, huanan, market."
23815,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.115942029,"the, was, in, and, that, for, a, of"
23816,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.115942029,"al., a, of, sars-cov-2, by, at, the, in"
23817,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.115942029,"that, the, of, sars-cov-2, and, this, likely, from"
23818,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.115942029,"sars-cov-2, of, based, the, and, cleavage, in, rbd"
23819,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.115942029,"in, the, of, to, that, human, and, a"
23820,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.115942029,"that, the, of, covid-19, in, viruses, a, to"
23821,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.115942029,"may, by, a, with, to, and, pangolins, are"
23822,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.115942029,"the, virus, have, animal, in, market, to, and"
23823,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.115942029,"a, of, the, has, been, by, that, to"
23824,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.115942029,"the, has, been, a, of, that, to, by"
23825,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.115942029,"that, the, from, a, in, to, and, spread"
23826,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.115942029,"the, to, as, reservoir, of, sars-cov-2, intermediate, and"
23827,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.115942029,"that, the, of, sars-cov-2, and, this, been, from"
23828,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.115942029,"sars-cov-2, to, are, several, and, coronaviruses, found, in"
23829,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.115942029,"is, a, sequence, coronaviruses, can, that, coronavirus, in"
23830,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.115942029,"this, that, natural, selection, in, and, the, of"
23831,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.115942029,"a, of, that, the, from, in, group, bats"
23832,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.115942029,"in, the, of, virus, is, to, that, a"
23833,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.115942029,"at, the, of, sars-cov-2, in, a, by, al."
23834,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.115942029,"in, of, was, a, found, from, to, sequence"
23835,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.115942029,"the, region, and, also, a, in, to, of"
23836,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.115942029,"and, with, are, to, pangolins, a, may, by"
23837,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.115942029,"the, of, are, cluster, with, bat, cov, pangolin"
23838,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.115942029,"evidence, to, could, in, bats, the, and, that"
23839,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.115942029,"the, of, and, that, from, this, suggests, likely"
23840,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.115942029,"and, the, likely, that, of, sars-cov-2, this, from"
23841,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.115942029,"from, and, this, the, of, that, sars-cov-2, been"
23842,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.115942029,"the, we, this, that, sars-cov-2, and, in, viruses"
23843,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.115942029,"and, sars-, cov-2,, to, the, bats, of, as"
23844,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.115942029,"of, the, bat, cov, are, cluster, with, pangolin"
23845,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.115942029,"that, the, selection, in, this, of, natural, and"
23846,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.115942029,"infectious, are, in, to, of, which, bats, and"
23847,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.115942029,"and, also, a, of, in, region, the, to"
23848,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.115942029,"analysis, of, the, virus, in, with, and, homology,"
23849,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.115942029,"sars-cov-2, the, rbd, and, cleavage, in, of, based"
23850,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.115789474,"the, to, of, based, is, on, was, that, by, animal, and"
23851,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.115789474,"the, animals, to, in, a, that, bats, infected, virus, and, market"
23852,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.115789474,"the, was, not, to, have, this, that, in, contact, with, of"
23853,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.115789474,"the, in, of, an, similar, to, that, this, was, also, virus"
23854,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.115789474,"based, on, the, of, and, that, is, animal, was, to, by"
23855,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.115789474,"that, the, virus, in, bats, and, to, infected, animals, a, market"
23856,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.115789474,"the, was, also, to, virus, that, similar, this, in, of, an"
23857,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.115789474,"this, that, the, was, with, of, in, not, have, contact, to"
23858,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.115702479,"in, the, animals, of, found, that, raccoon, at, virus, data, were, a, is, and"
23859,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.115702479,"a, at, the, of, and, in, data, raccoon, found, animals, virus, that, were, is"
23860,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.115384615,"in, the, of, that, a, bats"
23861,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.115384615,"are, human, coronaviruses, and, which, in"
23862,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.115384615,"a, sars-cov-2, and, sars-cov, bat, in"
23863,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.115384615,"human, to, a, and, which, viruses"
23864,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.115384615,"of, in, viruses"
23865,"Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.115384615,"of, animal, in"
23866,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.115384615,"animal, viruses, of"
23867,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.115384615,"in, animal, species"
23868,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.115384615,"bat, of, an"
23869,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.115384615,"and, have, the, southeast, asia,, china,"
23870,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.115384615,"of, are, to"
23871,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.115384615,"more, than, of, were, and, that"
23872,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.115384615,"such, to, in"
23873,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.115384615,"in, such, to"
23874,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.115384615,"is, to, one"
23875,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.115384615,"more, sars-cov-2, than"
23876,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.115384615,"coronavirus, is, and"
23877,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.115384615,"a, for, is"
23878,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.115384615,"is, and, for"
23879,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.115384615,"the, of, same"
23880,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.115384615,"from, of, to, and, the, infection"
23881,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.115384615,"in, the, of, as, a, used"
23882,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.115384615,"a, is, the, to, in, was"
23883,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.115384615,"in, a, of, to, the, was, is, being, as"
23884,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.115384615,"the, was, as, a, with, to"
23885,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.115384615,"the, of, to, it, is, as"
23886,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.115384615,"coronaviruses, that, to, sars-cov-2, including, from"
23887,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.115384615,"that, the, of, sars-cov-2, been, from"
23888,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.115384615,"that, sars-cov-2, the, closest, of, to"
23889,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.115384615,"found, the, of, to, sars-cov-2, in"
23890,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.115384615,"of, the, have, a, site, spike"
23891,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.115384615,"bat, be, the, of, sars-cov-2, and"
23892,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.115384615,"january, the, virus, was, a, that"
23893,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.115384615,"the, that, its, was, sars-cov-2, in, from, a, by"
23894,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.115384615,"that, sars-cov-2, did, from, a, in"
23895,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.115384615,"the, of, a, laboratory, and, to"
23896,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.115384615,"all, the, and, coronaviruses, that, of"
23897,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.115384615,"the, genome, that, to, bat, as"
23898,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.115384615,"it, was, that, the, a, of"
23899,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.115384615,"a, of, sars-cov-2, is, the, to"
23900,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.115384615,"the, of, and, a, viruses, are"
23901,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.115384615,"a, of, and, the, reservoir, including"
23902,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.115384615,"viruses, are, and"
23903,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.115384615,"sars-cov-2, to, and, is, known, in"
23904,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.115384615,"to, sars-cov-2, in, the, is, of"
23905,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.115384615,"sars-cov-2, to, are"
23906,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.115384615,"similar, to, of"
23907,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",Originating from reservoir of bat,0.115384615,"bat, of, from"
23908,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.115384615,"humans, that, the, be, and, sars-cov-2"
23909,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.115384615,"sars-cov-2, that, its, humans, to, the"
23910,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.115384615,"sars-cov-2, and, to, the, between, that"
23911,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.115384615,"a, of, that, the, in, bats"
23912,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.115384615,"as, a, of, the, in, used"
23913,evidence suggests bats as its origin,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.115384615,"bats, as, its"
23914,"bats are also important reservoir species for a great 

range of coronaviruses","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.115384615,"bats, are, also, for, a, of"
23915,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.115384615,"as, and, the, of, to, can, be, that, is"
23916,all three BANAL series viruses also use ACE2 as an entry receptor.,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.115384615,"also, use, ace2, as, an, entry"
23917,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.115384615,"to, the, coronavirus, in, bats, of, and, that, a"
23918,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.115384615,"a, the, in, was, is, to"
23919,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.115384615,"the, intermediate, hosts."
23920,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.115384615,"the, market, to, of, wuhan, on"
23921,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.115384615,"to, of, it, is, that, in"
23922,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.115384615,"a, sars-cov-2, and"
23923,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.115384615,"been, by, and, the, of, has"
23924,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.115384615,"the, that, has, been, by, and"
23925,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.115384615,"be, the, and"
23926,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.115384615,"be, of, natural, the, and, sars-"
23927,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.115384615,"the, reservoirs, and"
23928,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.115384615,"the, major, and"
23929,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.115384615,"the, that, as, to, from, animals"
23930,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",Bats are likely reservoir hosts for SARS-CoV-2,0.115384615,"sars-cov-2, reservoir, likely"
23931,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",zoonotic origins of SARS-CoV-2 by natural evolution,0.115384615,"of, sars-cov-2, zoonotic"
23932,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",zoonotic origins of SARS-CoV-2 by natural evolution,0.115384615,"origins, of, zoonotic"
23933,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",zoonotic origins of SARS-CoV-2 by natural evolution,0.115384615,"of, zoonotic, by"
23934,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.115384615,"the, and, other"
23935,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.115384615,"was, to, and"
23936,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.115384615,"sars-cov-2, of, and, that, the, with"
23937,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.115384615,"that, and, sars-cov-2, to, the, with"
23938,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","civet cats and raccoon dogs  

are the intermediate hosts",0.115384615,"the, and, are"
23939,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.115384615,"the, animals, that, are, to, and"
23940,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.115384615,"a, the, with, that, and, novel"
23941,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.115384615,"that, are, the, for, a, and"
23942,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.115384615,"transmitted, animal, to"
23943,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","with the first case being linked to  

a seafood market",0.115384615,"linked, to, the"
23944,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","with the first case being linked to  

a seafood market",0.115384615,"a, with, the"
23945,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.115384615,"the, of, sars-cov-2, is, to, humans"
23946,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.115384615,"in, to, the, sars-cov-2, has, from"
23947,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.115384615,"the, which, in"
23948,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.115384615,"that, a, zoonotic"
23949,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.115384615,"a, that, in"
23950,"The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.115384615,"the, zoonotic, and"
23951,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.115384615,"by, in, the"
23952,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.115384615,"the, pathway, and"
23953,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.115384615,"coronaviruses, have, a, species, to, and"
23954,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.115384615,"as, animal, reservoir, to, bat, species, have, high, and"
23955,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.115384615,"the, a, that, from, to, humans"
23956,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.115384615,"a, of, the, that, to, origin"
23957,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.115384615,"studies, have, the, of, and, these"
23958,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.115384615,"bat, and, have, the, they, ratg13"
23959,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.115384615,"the, was, that"
23960,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.115384615,"resulted, emergence, sars-cov-2"
23961,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.115384615,"the, of, lineage, that, sars-cov-2, at"
23962,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.115384615,"of, that, the, bat, a, from"
23963,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.115384615,"the, that, are, animals, to, and"
23964,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.115384615,"the, market, and, of, sars-cov-2, animals"
23965,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.115384615,"the, of, that, sars-cov-2, animals, to"
23966,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.115384615,"are, that, sars-cov-2, to, and, known"
23967,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.115384615,"at, that, the, of, sars-cov-2, lineage"
23968,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.115384615,"of, the, cases, huanan, and, that"
23969,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.115384615,"that, of, sars-cov-2, jumped, into, the"
23970,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.115384615,"that, sars-cov-2, and, hypothesis, the, of"
23971,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.115384615,"in, the, a, that, are, to"
23972,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.115384615,"in, the, a, at, and, with"
23973,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.115384615,"a, the, of, is, and, with"
23974,Bats are likely reservoir hosts for SARS-CoV-2,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.115384615,"likely, reservoir, sars-cov-2"
23975,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.115384615,"in, of, sars-cov-2, were, to, zoonotic"
23976,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.115384615,"the, in, a, as, to, spillover"
23977,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.115384615,"the, most, of"
23978,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.115384615,"of, more, than, and, that, were"
23979,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.115384615,"the, of, and, cases, huanan, that"
23980,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.115384615,"the, covid-19, of, to, that, and"
23981,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.115384615,"to, of, the, covid-19, and, was"
23982,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.115384615,"the, market, animals, sars-cov-2, and, of"
23983,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.115384615,"a, of, the, sars-cov-2, presence, and"
23984,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.115384615,"in, the, both, from, and, a"
23985,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor",0.115384615,"a, to, sars-cov-2"
23986,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.115384615,"the, animals, that, to, sars-cov-2, of"
23987,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.115384615,"that, in, from, a, spillover, to"
23988,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.115384615,"in, the, of, a, that, samples, from, humans, to"
23989,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.115384615,"known, and, sars-cov-2, is, to, in"
23990,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.115384615,"that, are, known, to, sars-cov-2, and"
23991,hese close genetic relations suggest that they all have their ecological origin in bat populations,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.115384615,"that, their, in"
23992,"preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.115384615,"evidence, that, their"
23993,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.115384615,"evidence, that, sars-cov-2"
23994,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.115384615,"animals, from, as, that, to, the"
23995,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.115384615,"the, in, a, spillover, as, to"
23996,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.115384615,"as, a, of, the, in, was, is, being, to"
23997,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.115384615,"for, from, to, the, market, in, of, team, a, tested, positive, was"
23998,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.115384615,"the, market, is, that, have, in, for, of, were, to, a, covid-19"
23999,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.115384615,"from, in, that, a, to, spillover"
24000,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.115384615,"as, a, the, was, to, with"
24001,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.115384615,"that, was, a, the, virus, january"
24002,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.115384615,"was, that, the, with, as, a"
24003,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.115384615,"was, a, with, and, to, the"
24004,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.115384615,"a, to, with, the, bat, and"
24005,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.115384615,"and, a, similarity, about, the, to"
24006,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.115384615,"have, to, a, and, coronaviruses, species"
24007,"Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.115384615,"is, and, coronavirus"
24008,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.115384615,"a, the, bat, high, and, sequence"
24009,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.115384615,"in, with, of"
24010,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.115384615,"the, a, of"
24011,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.115384615,"of, in, their, and, to, the"
24012,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.115384615,"from, that, virus, to, and, the"
24013,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.115384615,"has, and, the, of, virus, from"
24014,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.115384615,"and, to, the, of, has, is"
24015,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.115384615,"a, sars-cov-2, and, the, virus, from"
24016,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.115384615,"and, that, a, of, the, virus"
24017,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.115384615,"of, the, and, that, a, with"
24018,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.115384615,"that, the, and, bat, pangolin, which"
24019,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Bats have been reported as being the rich source of 

coronaviruses",0.115384615,"the, as, of"
24020,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","Bats have been reported as being the rich source of 

coronaviruses",0.115384615,"of, the, have"
24021,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.115384615,"from, to, a"
24022,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.115384615,"sars-cov-2, from, a"
24023,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.115384615,"the, pangolin, to"
24024,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.115384615,"sars-cov-2, from, to"
24025,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.115384615,"coronavirus, the, with"
24026,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.115384615,"sars-cov-2, has, with"
24027,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.115384615,"the, of, that, a, sars-cov-2, to"
24028,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.115384615,"one, is, to"
24029,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.115384615,"bat, and, the"
24030,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.115384615,"the, sars-cov-2, to, humans, of, is"
24031,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.115384615,"the, to, sars-cov-2, was, an, of"
24032,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.115384615,"the, of, humans, that, an, is"
24033,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.115384615,"who, that, the, a, and, to"
24034,zoonotic origins of SARS-CoV-2 by natural evolution,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.115384615,"zoonotic, origins, of"
24035,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.115384615,"of, the, covid-19, to, and, was"
24036,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.115384615,"genetic, and, shown, is, bats, of"
24037,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.115384615,"the, in, of, to, was, virus"
24038,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.115384615,"genetic, and, of, the, virus, is"
24039,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.115384615,"of, the, virus, to, which, and"
24040,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.115384615,"to, in, used"
24041,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.115384615,"to, in, covid-19"
24042,"natural selection in humans  

following zoonotic transfer","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.115384615,"natural, in, humans"
24043,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.115384615,"natural, the, in, to, that, naturally"
24044,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.115384615,"in, the, and"
24045,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.115384615,"that, in, animal"
24046,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.115384615,"the, bat, and"
24047,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.115384615,"the, and, to, be, of, is"
24048,"t some virus detected in pangolins 

were capable of infecting humans.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.115384615,"t, virus, of"
24049,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.115384615,"is, with, a, and, of, the"
24050,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.115384615,"the, bat, and, sequence, a, high"
24051,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.115384615,"a, of, the, with, sars-cov, and"
24052,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.115384615,"the, of, palm, as, a, human, and, civet, sequence"
24053,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.115384615,"and, bat, identity, high, the, of"
24054,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.115384615,"or, the, reservoir"
24055,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.115384615,"contact, be, the"
24056,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.115384615,"was, that, the, of, a, it"
24057,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.115384615,"the, was, as, a, that, with"
24058,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.115384615,"the, of, were, that, a, in, or, with, as"
24059,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.115384615,"the, seafood, it, that, or, was, of, in, a"
24060,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.115384615,"human, previous, coronavirus"
24061,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.115384615,"it, is, that, the, and, sars-cov-2"
24062,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.115384615,"is, sars-cov-2, and, to, the, that"
24063,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.115384615,"the, is, to, sars-cov-2, that, which"
24064,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.115384615,"the, with, was, to, of, at"
24065,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.115384615,"used, to, in"
24066,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.115384615,"human, in, all"
24067,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.115384615,"of, the, novel, and, with, bat"
24068,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.115384615,"sars-cov-2, genetic, similarity, with, the, cov"
24069,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.115384615,"the, bat, and, nucleotide, sequence, with"
24070,The virus which causes COVID-19 most probably has its ecological reservoir in bats,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.115384615,"the, has, reservoir"
24071,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.115384615,"that, from, human"
24072,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.115384615,"from, that, bat"
24073,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.115384615,"the, of, bat, coronaviruses, that, are"
24074,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.115384615,"from, that, are"
24075,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.115384615,"the, bat, of"
24076,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.115384615,"of, the, spike, in, a, those"
24077,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.115384615,"is, of, genetic, shown, bats, and"
24078,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.115384615,"that, have, by, recombination, of, and"
24079,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.115384615,"has, the, reservoir"
24080,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.115384615,"the, virus, in"
24081,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.115384615,"most, in, the"
24082,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.115384615,"animal, transmitted, to"
24083,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.115384615,"a, zoonotic, that"
24084,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.115384615,"a, from, to"
24085,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.115384615,"that, human, from"
24086,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.115384615,"zoonotic, transmitted, to"
24087,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.115384615,"from, to, is"
24088,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.115384615,"a, virus, an"
24089,"Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.115384615,"is, a, for"
24090,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.115384615,"is, coronaviruses, from, to, in, bats"
24091,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.115384615,"isolated, in, bats"
24092,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.115384615,"to, the, in, bats, of, outbreak"
24093,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.115384615,"that, in, their"
24094,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.115384615,"all, that, in"
24095,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.115384615,"the, and, in"
24096,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.115384615,"and, in, an, the, to, human"
24097,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.115384615,"bats, reservoir, virus"
24098,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.115384615,"sars-cov-2, is, and, from, species, that"
24099,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.115384615,"of, the, human, covid-19, in, with"
24100,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.115384615,"virus, reservoir, bats"
24101,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.115384615,"to, the, bats, be, of, with"
24102,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.115384615,"human, and, are, coronaviruses, in, which"
24103,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.115384615,"of, coronaviruses, and, which, in, with"
24104,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.115384615,"novel, with, bat, the, of, and"
24105,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.115384615,"that, to, genome, bat, as, the"
24106,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.115384615,"that, the, of, genome, bat, coronavirus"
24107,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.115384615,"in, of, with"
24108,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.115384615,"not, a, on, the, by, from"
24109,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.115384615,"sars-cov-2, to, or"
24110,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.115384615,"sars-cov-2, in, or"
24111,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.115384615,"sars-cov, and, sars-cov-2, bat, in, a"
24112,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.115384615,"the, virus, has, of, and, from"
24113,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.115384615,"sars-cov-2, a, virus, from, and, the"
24114,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.115384615,"the, virus, a, of, and, has"
24115,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.115384615,"the, of, sars-cov-2, a, virus, in"
24116,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.115384615,"a, from, sars-cov-2"
24117,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.115384615,"that, from, bat"
24118,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.115384615,"in, that, bat"
24119,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.115384615,"sars-cov-2, a, virus"
24120,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.115384615,"from, the, that, of, in, for"
24121,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.115384615,"in, the, of, intermediate, a, that, from, were, sequence"
24122,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.115384615,"the, analysis, that, likely, hosts, for"
24123,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.115384615,"the, a, novel, that, and, with"
24124,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.115384615,"the, and, a, presence, of, sars-cov-2"
24125,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.115384615,"two, the, of, that, a, sars-cov-2"
24126,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.115384615,"a, the, sars-cov, of, and, with"
24127,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.115384615,"that, the, of, coronaviruses, are, bat"
24128,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.115384615,"are, and, humans"
24129,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.115384615,"humans, and, the"
24130,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.115384615,"sars-cov-2, the, and"
24131,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Bats are natural hosts of many of the known  

coronaviruses",0.115384615,"coronaviruses, the, of"
24132,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Bats are natural hosts of many of the known  

coronaviruses",0.115384615,"natural, the, of"
24133,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Bats are natural hosts of many of the known  

coronaviruses",0.115384615,"the, of, bats, are, natural, hosts"
24134,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.115384615,"in, is, to, coronaviruses, from, bats"
24135,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.115384615,"is, that, sars-cov-2, species, and, from"
24136,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.115384615,"the, to, serve, as, of, intermediate"
24137,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.115384615,"the, most, be"
24138,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.115384615,"has, a, and, the, of, virus"
24139,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.115384615,"of, similar, to"
24140,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.115384615,"the, was, to, at, with, of"
24141,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.115384615,"closely, related, to"
24142,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.115384615,"a, the, of"
24143,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.115384615,"the, a, host"
24144,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.115384615,"the, are, with"
24145,"with the first case being linked to  

a seafood market","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.115384615,"the, linked, to"
24146,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.115384615,"bats, the, was, to, of, and"
24147,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.115384615,"the, of, sars-cov-2, an, was, to"
24148,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.115384615,"isolated, from, in, sars-cov-2, the, of"
24149,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.115384615,"sars-cov-2, a, and"
24150,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.115384615,"a, on, and, of, in, the"
24151,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.115384615,"on, the, in, and, that, for"
24152,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.115384615,"viruses, in, of"
24153,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.115384615,"sars-cov-2, a, between, and, from, as"
24154,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.115384615,"as, and, the, of, sars-cov-2, natural"
24155,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.115384615,"previous, human, coronavirus"
24156,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.115384615,"all, human, in"
24157,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.115384615,"human, and, to, a, which, viruses"
24158,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.115384615,"studies, these, and, have, the, of"
24159,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.115384615,"the, been, in, of, and, a"
24160,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.115384615,"to, sars-cov-2, in, the, for, of"
24161,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.115384615,"to, the, of, and, for, sars-cov-2"
24162,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.115384615,"cov, with, the, sars-cov-2, genetic, similarity"
24163,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.115384615,"a, to, coronaviruses,, may, the, bat"
24164,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.115384615,"the, is, wuhan, that, of, before, to, covid-19, had"
24165,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.115384615,"of, sars-cov-2, is, the, viruses, to"
24166,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.115384615,"the, of, is, for, in, a, virus, to, that"
24167,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.115384615,"in, a, study, the, of, with"
24168,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.115384615,"sars-cov-2, of, the, with, to, sars-, cov-2, in, analysis"
24169,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.115384615,"sars-cov-2, the, and, in, coronaviruses, of"
24170,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.115384615,"with, similarity, sars-cov-2"
24171,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.115384615,"sars-cov-2, in, a, of, that, with"
24172,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.115384615,"to, the, is"
24173,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.115384615,"is, the, sars-cov-2"
24174,zoonotic origins of SARS-CoV-2 by natural evolution,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.115384615,"zoonotic, of, by"
24175,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.115384615,"the, is, by, has, a, that"
24176,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.115384615,"that, the, of, sars-cov-2, and, is"
24177,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.115384615,"the, sars-cov-2, to, of, found, in"
24178,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.115384615,"the, sars-cov-2, has, to, from, in"
24179,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","bats are also important reservoir species for a great 

range of coronaviruses",0.115384615,"bats, are, also, a, for, of"
24180,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.115384615,"to, the, of, and, from, infection"
24181,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.115384615,"in, to, of, the, bats, and"
24182,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.115384615,"to, humans, of, and, in, bats"
24183,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.115384615,"nucleotide, sequence, with, bat, the, and"
24184,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.115384615,"to, amino, acid, in, ratg13, the"
24185,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.115384615,"the, rbd, to, sars-cov-2,, from, bats"
24186,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.115384615,"the, amino, acid, in, to, ratg13"
24187,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.115384615,"sars-cov-2, in, residues, the, with, as"
24188,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.115384615,"sars-cov-2, the, key, in, rbd, with"
24189,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.115384615,"as, the, of, is, can, and, be, that, to"
24190,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.115384615,"the, natural, of, sars-cov-2, as, and"
24191,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.115384615,"and, that, the, emergence, of, sars-cov-2"
24192,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.115384615,"the, residues, as, sars-cov-2, in, with"
24193,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.115384615,"sars-cov-2, a, and, in, animal, or"
24194,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.115384615,"the, sars-cov-2, with, that, and, to"
24195,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.115384615,"the, key, rbd, sars-cov-2, in, with"
24196,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.115384615,"that, the, hosts, for, sars-cov-2, to"
24197,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.115384615,"that, a, to, and, the, sars-cov-2"
24198,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.115384615,"of, the, sars-cov-2, obtained, is, and"
24199,"Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.115384615,"from, the, as"
24200,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.115384615,"to, as, the"
24201,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.115384615,"very, to, from"
24202,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.115384615,"laboratory, and, to, of, the, a"
24203,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.115384615,"that, the, and, to, who, a"
24204,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.115384615,"human, with, the, covid-19, in, of"
24205,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan",0.115384615,"in, of, animal"
24206,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.115384615,"in, the, of, from, that, for"
24207,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.115384615,"has, been, suggested, that, sars-cov-2, in"
24208,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.115384615,"at, the, it, that, or, of, sars-cov-2, from, a"
24209,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.115384615,"the, that, sars-cov-2, at, of, virus"
24210,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.115384615,"a, sars-cov-2, the, of, virus, in"
24211,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.115384615,"sars-cov-2, the, in, related, of, is"
24212,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.115384615,"in, a, of, sars-cov-2, to, zoonotic"
24213,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.115384615,"have, animal, reservoir, to, as, high, and, bat, species"
24214,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.115384615,"viruses, of, animal"
24215,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.115384615,"bats, and, for"
24216,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.115384615,"the, of, serve, as, intermediate, to"
24217,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.115384615,"in, the, to, that, sars-cov-2, and"
24218,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.115384615,"the, viruses, in, sars, and, to"
24219,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.115384615,"viruses, to, and"
24220,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.115384615,"between, and, the, southeast, in, china,"
24221,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.115384615,"of, covid-19, that, to, the, bat"
24222,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.115384615,"a, to, common, ancestor, with, sars-cov-2"
24223,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.115384615,"the, sars-cov-2, is, which, to, by"
24224,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.115384615,"he, is, similar, at, sars-cov-2, the"
24225,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.115384615,"the, was, a, with, and, to"
24226,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.115384615,"and, at, the, it, was, sars-cov-2, in, a, by"
24227,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.115384615,"discovered, a, with, the, sars-cov-2, in"
24228,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.115384615,"and, it, to, was, by, the, sars-cov-2, in, a"
24229,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.115384615,"the, sars-cov-2, with, at, and, to"
24230,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.115384615,"in, the, of, virus, for, is, to, that, a"
24231,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",all three BANAL series viruses also use ACE2 as an entry receptor.,0.115384615,"also, as, use, ace2, an, entry"
24232,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",all three BANAL series viruses also use ACE2 as an entry receptor.,0.115384615,"banal, series, also"
24233,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","This suggests that the BANAL series may be able to directly infect  

humans.",0.115384615,"suggests, that, the"
24234,"zoonotic corona- 

viruses have become an increasing threat to human health,","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.115384615,"viruses, to, human"
24235,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.115384615,"the, site, spike, have, a, of"
24236,"Bats have been reported as being the rich source of 

coronaviruses","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.115384615,"have, the, of"
24237,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.115384615,"a, is, to, sars-cov-2,, the, which"
24238,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.115384615,"two, related, and, which, have, to"
24239,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.115384615,"in, was, and"
24240,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.115384615,"in, isolated, bats"
24241,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.115384615,"sars-cov-2, is, the"
24242,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.115384615,"the, a, with, bat, and, to"
24243,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.115384615,"to, the, coronaviruses,, may, a, bat"
24244,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.115384615,"to, a, common, ancestor, with, sars-cov-2"
24245,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.115384615,"the, more, than, to, and, in"
24246,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.115384615,"recent, sars-cov-2, a, bat, to, in"
24247,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.115384615,"the, be, that, humans, and, sars-cov-2"
24248,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.115384615,"it, that, the, sars-cov-2, and, is"
24249,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.115384615,"on, the, of, to, market, wuhan"
24250,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.115384615,"that, by, a, of, virus, with, to, the, for"
24251,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.115384615,"that, the, with, in, were, or, as, a, of"
24252,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.115384615,"samples, from, in, humans, the, of, that, a, to"
24253,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.115384615,"a, the, palm, civet, as, of, and, sequence, human"
24254,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.115384615,"sequence, in, the, of, a, from, that, were, intermediate"
24255,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.115384615,"that, by, a, of, virus, with, similar, to, and, the, intermediate, for"
24256,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.115384615,"for, and, from, to, samples, at, the, in, of, team, collected, a, tested, positive, any"
24257,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.115384615,"in, a, team, of, to, the, was, from, market, for, tested, positive"
24258,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.115384615,"in, a, team, of, to, the, collected, samples, from, tested, positive, for, and, at, any"
24259,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.115384615,"in, a, of, to, have, the, that, covid-19, is, were, market, for"
24260,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.115384615,"is, that, the, wuhan, of, had, to, before, covid-19"
24261,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.115384615,"the, in, and, on, a, of"
24262,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.115384615,"is, to, origin, the, between, and"
24263,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.115384615,"a, of, to, origin, suggesting, zoonotic"
24264,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.115384615,"in, a, to, that, zoonotic, events"
24265,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.115384615,"that, sars-cov-2, was, from, a, by, the, its, in"
24266,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.115384615,"it, was, that, the, in, seafood, or, a, of"
24267,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.115384615,"it, that, sars-cov-2, a, the, of, or, at, from"
24268,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.115384615,"it, was, in, by, a, and, sars-cov-2, at, the"
24269,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.115384615,"the, its, to, that, humans, sars-cov-2"
24270,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.115384615,"the, sars-cov-2, virus, is, to, that"
24271,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.115384615,"a, is, to, its, the, that"
24272,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","expended to make the simple point 

that COVID-19 had a natural origin.",0.115384615,"a, to, the"
24273,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","expended to make the simple point 

that COVID-19 had a natural origin.",0.115384615,"the, to, covid-19"
24274,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.115384615,"sars-cov-2, that, to, coronaviruses, from, including"
24275,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.115384615,"to, in, and, that, bats, pangolins"
24276,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.115384615,"the, from, as"
24277,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.",0.115384615,"the, and, zoonotic"
24278,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.",0.115384615,"zoonotic, and, direct"
24279,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.",0.115384615,"direct, and, the"
24280,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.115384615,"the, of, and, their, in, to"
24281,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.115384615,"sars-cov-2, in, a, animal, and, or"
24282,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.115384615,"discovered, in, a, with, sars-cov-2, the"
24283,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.115384615,"of, that, coronavirus, through, a, laboratory"
24284,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.115384615,"that, of, sars-cov-2"
24285,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.115384615,"as, of, the, it, is, to"
24286,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.115384615,"similarity, of, is, the, for, to"
24287,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.115384615,"to, sars-cov-2,, a, the, which, is"
24288,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.115384615,"is, a, that, its, to, the"
24289,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.115384615,"sars-cov-2, to, the, for, in, of"
24290,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.115384615,"the, a, of, which, that, and"
24291,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.115384615,"that, by, a, of, and, the"
24292,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.115384615,"the, of, that, sars-cov-2, jumped, into"
24293,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.115384615,"of, that, the, is, a, possible"
24294,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.115384615,"in, to, of, the, virus, was"
24295,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.115384615,"the, of, sars-cov-2, to, that, this"
24296,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.115384615,"of, the, sars-cov-2, pangolins, from, and"
24297,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.115384615,"the, and, all, of, coronaviruses, that"
24298,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.115384615,"the, of, coronaviruses, and, in, sars-cov-2"
24299,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.115384615,"the, is, of, sars-cov-2, related, in"
24300,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","In the 

case of MERS, dromedaries were the principal host.",0.115384615,"the, in, were"
24301,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.",0.115384615,"study, of, a, in, with, the"
24302,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.115384615,"the, genome, of, coronavirus, that, bat"
24303,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.115384615,"the, sars, and, viruses, to, in"
24304,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.115384615,"to, in, more, than, the, and"
24305,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.115384615,"a, bat, that, the, of, from"
24306,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.115384615,"is, possible, that, a, of, the"
24307,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.115384615,"these, a, diversity, of, the, as"
24308,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.115384615,"transmitted, to, zoonotic"
24309,"The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.115384615,"direct, zoonotic, and"
24310,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.115384615,"covs, zoonotic, and, to, animals, through"
24311,hese close genetic relations suggest that they all have their ecological origin in bat populations,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.115384615,"that, all, in"
24312,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",Bats are hosts of many coronaviruses,0.115384615,"of, bats, hosts"
24313,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.115384615,"in, animal, humans"
24314,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.115384615,"to, in, the"
24315,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.115384615,"is, in, the"
24316,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.115384615,"the, been, of, that, most, by"
24317,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.115384615,"that, the, of, bat, covid-19, to"
24318,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.115384615,"bats, a, coronavirus, the, of, and, in, that, to"
24319,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.115384615,"the, of, outbreak, in, to, bats"
24320,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.115384615,"the, of, a, and, been, in"
24321,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.115384615,"and, that, in, the, emergence, of"
24322,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.115384615,"in, viruses, are, and, all, guangdong, that, the, between"
24323,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.115384615,"in, were, found, be, with, that"
24324,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.115384615,"to, this, that, has, the, of"
24325,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.115384615,"that, with, the, of, have, to"
24326,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.115384615,"of, the, a, diversity, these, as"
24327,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.115384615,"several, of, the, one, reservoir, species"
24328,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.115384615,"the, or, of"
24329,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.115384615,"in, of, bats, to, and, humans"
24330,"Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.115384615,"contact, the, be"
24331,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.115384615,"is, from, to"
24332,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.115384615,"the, and, humans"
24333,"The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.115384615,"the, direct, and"
24334,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.115384615,"be, from, to, hunters, bats, and"
24335,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.115384615,"from, to, and"
24336,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.115384615,"the, from, and"
24337,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.115384615,"from, bats, to, and, hunters, be"
24338,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.115384615,"was, the, of"
24339,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.115384615,"a, was, market, in, the, of"
24340,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.115384615,"the, of, sars-cov-2, obtained, is, and"
24341,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.115384615,"the, of, from, pangolins, and, sars-cov-2"
24342,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.115384615,"he, is, similar, sars-cov-2, at, the"
24343,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.115384615,"the, by, in"
24344,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.115384615,"the, have, and, southeast, asia,, china,"
24345,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.115384615,"southeast, and, china,, between, in, the"
24346,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.115384615,"the, reservoir, of, a, including, and"
24347,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.115384615,"covs, zoonotic, animals, and, to, through"
24348,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.115384615,"one, several, species, of, the, reservoir"
24349,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.115384615,"a, sars-cov-2, with, suggesting, that, common"
24350,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","zoonotic corona- 

viruses have become an increasing threat to human health,",0.115384615,"to, viruses, human"
24351,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.115384615,"to, the, that, a, of, origin"
24352,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.115384615,"have, that, are, the, a, of"
24353,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.115384615,"the, coronavirus, with"
24354,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.115384615,"the, most, in"
24355,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.115384615,"with, are, the"
24356,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.115384615,"that, sars-cov-2, from, a, did, in"
24357,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.115384615,"a, to, in, recent, sars-cov-2, bat"
24358,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.115384615,"the, of, that, is, an, humans"
24359,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.115384615,"it, was, in, by, a, and, to, sars-cov-2, the"
24360,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.115384615,"of, sars-cov-2, the"
24361,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.115384615,"sars-cov-2, in, has, been, suggested, that"
24362,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.115384615,"in, humans, animal"
24363,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.115384615,"the, virus, a, of, that, and"
24364,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.115384615,"is, of, the, virus, genetic, and"
24365,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.115384615,"of, that, the, is, origin, a"
24366,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.115384615,"of, sars-cov-2, also, the, scenario, these"
24367,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.115384615,"has, been, and, the, of, by"
24368,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.115384615,"the, has, is, to, of, and"
24369,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.115384615,"sars-cov-2, is, to, have, in, the"
24370,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.115384615,"on, the, by, not, from, a"
24371,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.115384615,"are, and, viruses"
24372,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.115384615,"was, and, to"
24373,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.115384615,"from, to, sars-cov-2"
24374,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.115384615,"that, are, from"
24375,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.115384615,"and, viruses, to"
24376,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.115384615,"that, viruses, from"
24377,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.115384615,"the, be, most"
24378,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.115384615,"from, viruses, that"
24379,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.115384615,"has, been, that, and, the, by"
24380,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.115384615,"the, between, and, is, origin, to"
24381,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.115384615,"the, this, that, is, has, been"
24382,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.115384615,"the, these, also, scenario, of, sars-cov-2"
24383,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.115384615,"the, that, has, is, by, a"
24384,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.115384615,"that, the, and, to, from, a"
24385,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.115384615,"bats, for, and"
24386,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.115384615,"analysis, the, that, likely, hosts, for"
24387,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.115384615,"in, the, of, a, was, market"
24388,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.115384615,"that, hosts, for, sars-cov-2, to, the"
24389,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.115384615,"to, of, the, virus, which, and"
24390,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.115384615,"the, a, about, and, similarity, to"
24391,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.115384615,"the, human, an, in, to, and"
24392,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.115384615,"is, the, of, viruses, to, sars-cov-2"
24393,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.115384615,"the, similarity, of, to, is, for"
24394,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.115384615,"two, related, to, and, have, which"
24395,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.115384615,"genome, sequences, in, of, and, covs"
24396,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.115384615,"and, have, that, by, recombination, of"
24397,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.115384615,"a, of, that, for, with, by, the, to, virus"
24398,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.115384615,"by, the, of, a, to, that, with, intermediate, and, virus, similar, for"
24399,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.115384615,"the, that, are, hosts, for, sars-cov-2"
24400,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.115384615,"that, through, laboratory, of, a, coronavirus"
24401,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.115384615,"the, as, to"
24402,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.115384615,"the, a, of, with, that, and"
24403,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.115384615,"to, sars-cov-2, is"
24404,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.115384615,"the, of, is"
24405,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.115384615,"the, in, and, on, that, for"
24406,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.115384615,"that, to, in, bats, and, pangolins"
24407,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.115384615,"this, that, sars-cov-2, the, bats, we"
24408,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.115384615,"sars-cov-2, the, of, that, been, from"
24409,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.115384615,"the, to, that, between, and, sars-cov-2"
24410,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.115384615,"that, the, sars-cov-2, and, to, is"
24411,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.115384615,"that, are, the, all, and, viruses, in, guangdong, between"
24412,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.115384615,"have, in, to, the, sars-cov-2, is"
24413,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.115384615,"the, of, bat"
24414,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.115384615,"or, of, the"
24415,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.115384615,"that, are, the, hosts, for, sars-cov-2"
24416,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.115384615,"the, which, that, pangolin, and, bat"
24417,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.115384615,"more, than, sars-cov-2"
24418,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.115384615,"that, sars-cov-2, likely"
24419,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.115384615,"and, they, have, the, bat, ratg13"
24420,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.115384615,"in, of, covs, genome, sequences, and"
24421,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.115384615,"the, of, and, hypothesis, that, sars-cov-2"
24422,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.115384615,"has, with, sars-cov-2"
24423,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.115384615,"and, the, of, to, sars-cov-2, is"
24424,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.115384615,"the, same, of"
24425,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.115384615,"the, and, pathway"
24426,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.115384615,"from, and, the"
24427,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.115384615,"sars-cov-2, emergence, resulted"
24428,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.115384615,"and, the, of, that, emergence, sars-cov-2"
24429,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.115384615,"the, in, of, and, that, emergence"
24430,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.115384615,"in, the, from, and, a, both"
24431,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.115384615,"the, a, that, are, and, for"
24432,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.115384615,"the, of, a, that, hosts, for"
24433,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.115384615,"a, of, the, are, that, have"
24434,"Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.115384615,"is, for, and"
24435,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.115384615,"and, the, major"
24436,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.115384615,"sars-cov-2, to, in"
24437,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.115384615,"to, and, the"
24438,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.115384615,"sars-cov-2, the, and, to, in, binding"
24439,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.115384615,"in, of, and, that, the, for"
24440,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.115384615,"that, sars-cov-2, the, of, virus, at"
24441,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.115384615,"with, and, to, sars-cov-2, at, the"
24442,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.115384615,"and, similarity, of, sars-cov-2, the, to"
24443,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.115384615,"the, of, not, to, that, sars-cov-2"
24444,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.115384615,"the, rbd, bats, from, to, sars-cov-2,"
24445,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.115384615,"that, the, sars-cov-2, to, which, is"
24446,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.115384615,"the, to, this, that, has, of"
24447,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.115384615,"this, the, sars-cov-2, we, that, bats"
24448,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.115384615,"that, was, the"
24449,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.115384615,"is, to, that"
24450,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.115384615,"from, to, very"
24451,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.115384615,"that, likely, sars-cov-2"
24452,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.115384615,"of, the, most"
24453,"An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.115384615,"an, of, bat"
24454,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.115384615,"the, sars-cov-2, and, be, of, bat"
24455,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.115384615,"virus, an, a"
24456,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.115384615,"the, sars-cov-2, and"
24457,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.115384615,"is, the, that, has, been, this"
24458,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.115384615,"in, a, of, for, sars-cov-2, that"
24459,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.115384615,"and, to, the, of, natural, is"
24460,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.115384615,"were, zoonotic, of, sars-cov-2, in, to"
24461,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.115384615,"of, zoonotic, sars-cov-2, to, a, in"
24462,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.115384615,"of, suggesting, a, zoonotic, origin, to"
24463,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.115384615,"a, zoonotic, in, events, that, to"
24464,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.115384615,"that, be, found, in, with, were"
24465,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.115384615,"with, suggesting, that, sars-cov-2, a, common"
24466,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.115384615,"of, that, sars-cov-2, a, in, for"
24467,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",evidence suggests bats as its origin,0.115384615,"its, as, bats"
24468,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.115384615,"the, natural, to, that, in, naturally"
24469,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.115384615,"of, the, spike, those, in, a"
24470,"Bats are natural hosts of many of the known  

coronaviruses","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.115384615,"bats, are, natural, hosts, of, the"
24471,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.115384615,"of, that, to, in, it, is"
24472,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.115384615,"of, sars-, cov-2, to, in, with, sars-cov-2, analysis, the"
24473,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.115384615,"the, of, bat, high, and, identity"
24474,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.115044248,"to, bats, as, be, and, a, in, species, from, high, sequence, that, coronaviruses"
24475,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.115044248,"the, of, a, in, to, that, bats, with, and, it, coronaviruses, south, asia"
24476,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.115044248,"a, sequence, and, coronaviruses, from, species, be, as, high, to, that, in, bats"
24477,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.115044248,"to, a, of, in, bats, the, asia, and, south, it, that, with, coronaviruses"
24478,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.114942529,"such, have, and, in, to, the, of, sars-cov-2, origin, has"
24479,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.114942529,"in, the, of, and, to, other, be, some, sign, genetic"
24480,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.114942529,"the, and, some, to, be, sign, of, genetic, in, other"
24481,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.114942529,"the, of, to, they, that, close, this, in, which, virus"
24482,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.114942529,"the, are, to, in, a, was, bats, virus, and, market"
24483,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.114942529,"this, of, to, the, in, which, that, they, virus, close"
24484,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.114942529,"of, natural, on, the, discovery, similar, to, in, virus, genetic"
24485,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.114942529,"are, and, the, virus, was, bats, to, a, market, in"
24486,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.114942529,"of, virus, that, is, most, to, the, and, for, was"
24487,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.114942529,"a, january, 2020, and, were, to, of, in, the, huanan"
24488,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.114942529,"the, huanan, in, of, january, 2020, were, to, and, a"
24489,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.114942529,"the, to, for, of, is, most, was, that, virus, and"
24490,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.114942529,"sars-cov-2, origin, of, has, to, such, have, in, and, the"
24491,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.114942529,"the, of, on, natural, in, virus, similar, to, discovery, genetic"
24492,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.114754098,"the, in, and, that, bats, or, pangolins"
24493,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.114754098,"and, a, in, to, bat, coronaviruses, are"
24494,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.114754098,"and, to, be, the, of, bats, are"
24495,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.114754098,"virus, for, of, with, that, coronavirus, and"
24496,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.114754098,"that, of, virus, with, one, and, for"
24497,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.114754098,"that, sars-cov-2, from, the, nor, genetic, any"
24498,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.114754098,"the, of, it, to, that, sars-cov-2, been"
24499,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.114754098,"sars-cov-2, the, genetic, any, that, nor, from"
24500,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.114754098,"is, a, the, in, its, by, from"
24501,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.114754098,"the, of, that, viruses, human, and, to"
24502,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.114754098,"cov, sequence, bat, that, the, sars-cov-2, and"
24503,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.114754098,"in, and, sars-cov-2, with, bat, the, is"
24504,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.114754098,"bats, are, the, of, and, viruses, have"
24505,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.114754098,"sars-cov, spread, and, to, was, the, in"
24506,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.114754098,"the, and, that, was, transmitted, to, humans"
24507,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.114754098,"sars-cov-2, is, from, be, to, in, bats"
24508,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.114754098,"and, the, that, zoonotic, in, a, by"
24509,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.114754098,"have, been, and, in, to, sars-cov-2, elsewhere"
24510,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.114754098,"to, been, identified, from, an, between, and"
24511,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.114754098,"from, was, at, wuhan, that, the, of"
24512,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.114754098,"the, and, that, these, bat, not, of"
24513,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.114754098,"to, sars-cov-2, from, a, of, the, that"
24514,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.114754098,"a, of, the, and, 2019, with, huanan"
24515,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.114754098,"in, and, with, this, the, origin, is"
24516,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.114754098,"the, been, of, most, from, hosts, and"
24517,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.114754098,"the, in, and, from, animals, a, market"
24518,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.114754098,"the, of, have, that, sars-cov-2, to, humans"
24519,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.114754098,"and, that, sars-cov-2, is, an, was, to"
24520,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.114754098,"to, and, it, is, that, viruses, in"
24521,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.114754098,"in, the, of, a, was, first, market"
24522,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.114754098,"the, sars-cov-2, and, of, is, to, that"
24523,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.114754098,"the, of, that, sars-cov-2, was, to, but"
24524,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.114754098,"evidence, that, the, of, have, to, an"
24525,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.114754098,"and, from, were, indicating, that, the, is"
24526,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.114754098,"from, that, the, virus, is, to, of"
24527,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.114754098,"of, and, that, for, virus, with, coronavirus"
24528,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.114754098,"from, to, the, sars-cov-2, have, been, a"
24529,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.114754098,"available, by, a, of, the, that, and"
24530,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.114754098,"the, was, that, transmitted, to, humans, and"
24531,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.114754098,"that, was, an, sars-cov-2, to, and, is"
24532,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.114754098,"to, that, the, of, and, have, sars-cov-2"
24533,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.114754098,"in, the, market, from, and, a, animals"
24534,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.114754098,"a, the, at, that, have, to, virus"
24535,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.114754098,"in, that, animal, had, the, to, virus"
24536,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.114754098,"in, the, of, and, reported, huanan, seafood"
24537,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.114754098,"the, of, that, virus, to, and, sequence"
24538,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.114754098,"bats, related, to, that, severe, acute, respiratory"
24539,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.114754098,"the, of, suggested, that, may, as, was"
24540,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.114754098,"the, of, not, that, with, host,, a"
24541,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.114754098,"the, bat, cov, and, sequence, that, sars-cov-2"
24542,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.114754098,"from, reservoir, it, the, of, that, been"
24543,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.114754098,"on, by, of, receptor, binding, and, that"
24544,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.114754098,"the, genome, of, and, bat, sequence, genomes"
24545,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.114754098,"of, human, are, associated, with, and, in"
24546,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.114754098,"the, results, to, that, sars-cov-2, is, of"
24547,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.114754098,"to, that, the, of, coronavirus, is, sars-cov-2"
24548,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.114754098,"genome, sequence, and, the, of, from, bat"
24549,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.114754098,"the, genome, sequence, of, from, bat, and"
24550,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.114754098,"of, the, genome, sequence, and, genomes, bat"
24551,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.114754098,"the, sequences, of, coronaviruses, and, in, genome"
24552,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.114754098,"are, a, and, in, the, that, to"
24553,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.114754098,"genome, overall, sequence, bat, that, and, a"
24554,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.114754098,"revealed, that, the, nucleic, of, sars-cov-2, which"
24555,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.114754098,"sars-cov-2, to, from, bats, in, is, be"
24556,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.114754098,"bat, coronavirus, to, as, is, which, sars-cov-2"
24557,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.114754098,"revealed, that, of, sars-cov-2, nucleic, the, which"
24558,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.114754098,"was, suggested, that, the, may, as, of"
24559,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.114754098,"a, that, the, virus, is, to, of"
24560,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.114754098,"in, to, that, the, of, sars-, coronavirus"
24561,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.114754098,"huanan, seafood, in, the, reported, and, of"
24562,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.114754098,"that, was, the, of, sars-cov-2, but, to"
24563,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.114754098,"the, with, of, natural, it, as, for"
24564,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.114754098,"sars-cov, had, and, to, not, for, the, of, that, sars-cov-2, may, have, been, in"
24565,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.114754098,"december, 2019,, had, to, any, and, the"
24566,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.114754098,"sars-cov-2, the, of, that, been, to, it"
24567,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.114754098,"a, of, the, host,, with, that, not"
24568,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.114754098,"2, to, the, in, and, that, for"
24569,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.114754098,"the, that, in, a, to, from, humans"
24570,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.114754098,"the, sequences, of, from, in, with, sars-cov-2"
24571,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.114754098,"the, of, that, sars-cov-2, is, a, in"
24572,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.114754098,"the, genome, of, and, coronaviruses, sequences, in"
24573,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.114754098,"of, from, in, with, sars-cov-2, sequences, the"
24574,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.114754098,"to, in, the, that, it, may, bind"
24575,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.114754098,"to, sars-cov-2, a, in, the, and, that"
24576,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.114754098,"a, that, the, to, and, in, sars-cov-2"
24577,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.114754098,"and, the, of, that, cleavage, site, a"
24578,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.114754098,"of, to, is, a, in, sars-cov-2, the"
24579,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.114754098,"in, horseshoe, bats, are, more, of, and"
24580,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.114754098,"sars-cov-2, is, bat, as, to, which, coronavirus"
24581,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.114754098,"are, to, the, whole, genome, in, and"
24582,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.114754098,"with, a, and, of, the, huanan, 2019"
24583,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.114754098,"a, of, available, that, by, the, and"
24584,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.114754098,"the, virus, to, that, had, in, animal"
24585,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.114754098,"that, the, virus, and, of, sequence, to"
24586,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.114754098,"to, december, 2019,, had, any, and, the"
24587,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.114754098,"and, a, of, in, which, the, to"
24588,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.114754098,"a, of, zoonotic, and, the, to, one"
24589,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.114754098,"a, seafood, market, the, is, to, of"
24590,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.114754098,"the, and, that, a, in, are, to"
24591,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.114754098,"the, and, a, in, to, that, are"
24592,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.114754098,"of, are, human, and, in, associated, with"
24593,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.114754098,"all, the, and, in, that, of, is"
24594,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.114754098,"the, and, by, a, zoonotic, that, in"
24595,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.114754098,"it, in, the, to, bind, that, may"
24596,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.114754098,"in, is, sars-cov-2, the, of, binding, protein"
24597,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.114754098,"a, of, the, and, that, cleavage, site"
24598,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.114754098,"the, by, of, and, that, natural, a"
24599,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.114754098,"the, genomic, features, of, that, through, a"
24600,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.114754098,"the, is, that, of, and, in, all"
24601,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.114754098,"the, viruses, and, of, that, to, human"
24602,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.114754098,"that, a, of, the, intermediate, hosts, for"
24603,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.114754098,"bats, hosts, of, and, to, that, in"
24604,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.114754098,"bats, are, the, have, of, and, viruses"
24605,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.114754098,"and, guangdong, the, between, viruses, that, in"
24606,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.114754098,"in, the, by, is, bat, sars-, cov-2"
24607,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.114754098,"in, a, of, the, was, first, market"
24608,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.114754098,"sars-cov-2, in, the, protein, binding, is, of"
24609,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.114754098,"the, and, one, of, a, zoonotic, to"
24610,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.114754098,"and, most, been, the, of, from, hosts"
24611,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.114754098,"genome, and, bat, that, a, sequence, overall"
24612,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.114754098,"and, has, a, suggesting, that, bat, common"
24613,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.114754098,"have, that, the, virus, to, at, a"
24614,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.114754098,"the, sars-cov, was, in, and, spread, to"
24615,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.114754098,"a, from, the, been, to, have, sars-cov-2"
24616,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.114754098,"it, been, that, the, of, from, reservoir"
24617,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.114754098,"sars-cov-2, and, of, the, have, been, to, in, not, had, sars-cov, that, for, may"
24618,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.114754098,"with, the, of, as, natural, for, it"
24619,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.114754098,"sars-cov-2, have, been, to, and, in, elsewhere"
24620,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.114754098,"is, from, a, by, the, its, in"
24621,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.114754098,"are, more, of, horseshoe, bats, in, and"
24622,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.114754098,"been, from, an, to, identified, between, and"
24623,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.114754098,"that, from, the, was, at, wuhan, of"
24624,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.114754098,"the, virus, is, to, that, of, from"
24625,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.114754098,"the, is, that, virus, to, a, of"
24626,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.114754098,"the, seafood, market, is, of, a, to"
24627,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.114754098,"2, viruses, to, the, in, and, for"
24628,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.114754098,"one, of, and, that, for, virus, with"
24629,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.114754098,"of, that, the, a, intermediate, hosts, for"
24630,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.114754098,"on, receptor, binding, and, that, by, of"
24631,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.114754098,"and, the, of, that, by, a, natural"
24632,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.114754098,"that, a, of, the, genomic, features, through"
24633,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.114754098,"other, that, and, a, on, the, of"
24634,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.114754098,"and, that, the, or, in, bats, pangolins"
24635,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.114754098,"in, the, for, 2, to, that, and"
24636,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.114754098,"in, and, are, to, the, whole, genome"
24637,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.114754098,"and, in, the, for, viruses, to, 2"
24638,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.114754098,"that, the, and, viruses, in, guangdong, between"
24639,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.114754098,"with, the, and, sars-cov-2, is, bat, in"
24640,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.114754098,"this, is, with, and, origin, the, in"
24641,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.114754098,"results, of, the, that, sars-cov-2, is, to"
24642,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.114754098,"the, sars-, cov-2, is, by, bat, in"
24643,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.114754098,"the, of, and, have, that, sars-cov-2, to"
24644,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.114754098,"on, the, other, of, and, that, a"
24645,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.114754098,"sars-cov-2, of, the, and, with, to, virus"
24646,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.114754098,"in, and, bat, this, that, the, between"
24647,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.114754098,"the, sars-cov-2, which, to, of, is, in"
24648,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.114754098,"that, of, is, a, in, sars-cov-2, the"
24649,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.114754098,"that, related, to, severe, acute, respiratory, bats"
24650,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.114754098,"that, in, bats, and, to, hosts, of"
24651,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.114754098,"r., in, to, that, the, of, sars-cov-2"
24652,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.114754098,"that, were, from, the, and, indicating, is"
24653,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.114754098,"of, the, that, sars-cov-2, coronavirus, is, to"
24654,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.114754098,"coronavirus, in, the, that, to, of, sars-"
24655,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.114754098,"in, r., to, that, of, sars-cov-2, the"
24656,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.114754098,"and, are, to, bat, coronaviruses, in, a"
24657,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.114754098,"these, and, that, not, the, bat, of"
24658,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.114754098,"the, that, to, a, of, and, has"
24659,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.114754098,"has, bat, suggesting, that, and, a, common"
24660,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.114754098,"the, of, that, are, to, a, bat"
24661,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.114754098,"that, it, to, and, is, viruses, in"
24662,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.114754098,"have, to, an, the, of, evidence, that"
24663,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.114754098,"the, sars-cov-2, with, of, virus, and, to"
24664,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.114583333,"in, a, to, coronaviruses, which, bat, and, viruses, closely, related, other"
24665,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.114583333,"in, of, coronaviruses, the, collected, from, which, two, and, genome, were"
24666,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.114583333,"and, closely, related, to, bat, coronaviruses, in, a, which, other, viruses"
24667,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.114583333,"the, of, coronaviruses, from, two, and, which, were, collected, in, genome"
24668,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.114285714,"of, in, viruses, a"
24669,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.114285714,"bats, reservoir, of, coronaviruses"
24670,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.114285714,"to, a, human, called"
24671,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.114285714,"sars-cov-2, are, and, other"
24672,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.114285714,"sars-cov-2, a, to, sars-cov"
24673,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.114285714,"of, in, a, viruses"
24674,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.114285714,"from, are, bats, the"
24675,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.114285714,"the, as, in, well"
24676,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.114285714,"the, viruses,, from, in"
24677,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.114285714,"the, are, to, of"
24678,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.114285714,"bats, are, to, be"
24679,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.114285714,"many, coronaviruses, such, and"
24680,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.114285714,"to, many, bat, and"
24681,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.114285714,"bats, of, and, to"
24682,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.114285714,"and, to, in, of"
24683,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.114285714,"in, to, of, sars-cov-2"
24684,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.114285714,"such, to, sars-cov-2, in"
24685,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.114285714,"the, are, of, emergence"
24686,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.114285714,"of, sars-cov-2, been, coronavirus"
24687,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.114285714,"origin, of, sars-cov-2, a"
24688,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.114285714,"sars-cov-2, is, a, and"
24689,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.114285714,"with, a, sars-cov-2, is"
24690,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.114285714,"is, that, virus, and"
24691,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.114285714,"genetic, sars-cov-2, with, other"
24692,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.114285714,"thus, that, sars-cov-2, with"
24693,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.114285714,"the, are, emergence, of"
24694,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.114285714,"the, host, to, as"
24695,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.114285714,"the, natural, sars-cov-2, as"
24696,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.114285714,"several, to, sars-cov-2, the"
24697,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.114285714,"the, sars-cov, was, to"
24698,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.114285714,"the, was, to, a"
24699,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.114285714,"sequence, shares, that, of"
24700,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.114285714,"the, was, that, bat"
24701,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.114285714,"genome, of, and, bat"
24702,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.114285714,"and, bat, origin, of"
24703,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.114285714,"natural, and, virus, of"
24704,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.114285714,"the, are, and, including"
24705,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.114285714,"the, of, sars-cov-like, reservoir"
24706,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.114285714,"the, of, and, mers-"
24707,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.114285714,"the, and, to, that, sars-cov-2, bat, cov, ratg13"
24708,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.114285714,"of, sars-cov-2, between, and"
24709,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.114285714,"between, and, of, sars-cov-2"
24710,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.114285714,"sars-cov-2, the, with, bat"
24711,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.114285714,"the, in, that, as"
24712,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.114285714,"a, the, to, similarity"
24713,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.114285714,"that, similarity, to, and"
24714,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.114285714,"of, the, bats, for"
24715,"Bats have been reported as being the rich source of 

coronaviruses","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.114285714,"been, as, the, of"
24716,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.114285714,"sars-cov-2, and, is, a"
24717,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.114285714,"the, most, has, bats"
24718,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.114285714,"are, the, sources, of"
24719,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.114285714,"be, bats, and, the"
24720,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.114285714,"the, with, of, at"
24721,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.114285714,"sars-cov-2, sequenced, the, of"
24722,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.114285714,"through, the, of, with"
24723,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.114285714,"was, from, identical, to"
24724,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.114285714,"the, to, identical, in"
24725,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",zoonotic origins of SARS-CoV-2 by natural evolution,0.114285714,"by, of, sars-cov-2, natural"
24726,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.114285714,"sars-cov-2, with, is, a"
24727,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.114285714,"is, from, a, to"
24728,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.114285714,"a, to, sars-cov-2, the"
24729,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.114285714,"sars-cov-2, to, the, zoonotic"
24730,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.114285714,"sars-cov-2, to, bats,, the"
24731,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.114285714,"the, from, bats,, a"
24732,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.114285714,"sars-cov-2, high, to, the"
24733,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.114285714,"coronaviruses, to, the, and"
24734,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.114285714,"of, the, to, coronaviruses"
24735,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.114285714,"was, the, to, sars-cov"
24736,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.114285714,"in, other, animals, and"
24737,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.114285714,"to, and, was, the"
24738,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.114285714,"that, sars-cov-2, bat, the"
24739,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.114285714,"of, the, protein, in"
24740,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.114285714,"of, bat, in, sars-cov-2"
24741,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.114285714,"genome, and, bat, of"
24742,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.114285714,"the, of, bats, for"
24743,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.114285714,"are, that, the, of"
24744,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.114285714,"that, bats, of, sars-covs"
24745,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.114285714,"the, of, that, outbreak"
24746,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.114285714,"the, of, that, natural"
24747,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.114285714,"of, that, the, sars"
24748,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.114285714,"a, and, coronaviruses, from, to, that, coronavirus, in"
24749,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.114285714,"the, animal, to, and"
24750,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.114285714,"and, the, to, of"
24751,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.114285714,"to, the, of, be"
24752,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","with the first case being linked to  

a seafood market",0.114285714,"the, first, to, with"
24753,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.114285714,"has, been, to, in"
24754,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.114285714,"in, the, that, a"
24755,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.114285714,"the, a, that, and"
24756,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.114285714,"a, that, the, in"
24757,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.114285714,"a, virus, the, it"
24758,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.114285714,"the, hypothesis, that, a"
24759,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.114285714,"the, other, not, been"
24760,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.114285714,"several, a, have, and, to, from, reservoir, species"
24761,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.114285714,"that, the, sars-cov-2, to, hypothesis, of, natural, origin"
24762,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.114285714,"are, the, natural, and"
24763,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.114285714,"the, has, have, sars-cov-2"
24764,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.114285714,"has, that, the, are"
24765,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.114285714,"from, and, was, not, the, of, that, have"
24766,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.114285714,"sars-cov-2, that, was, the"
24767,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.114285714,"the, hypothesis, that, of"
24768,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.114285714,"bats, and, pangolins, sars-cov-2"
24769,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.114285714,"the, to, of, bat"
24770,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.114285714,"the, intermediate, host, of"
24771,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.114285714,"from, animals, the, market"
24772,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.114285714,"for, the, zoonotic, of"
24773,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.114285714,"for, the, of, sars-cov-2"
24774,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.114285714,"that, are, the, sars-cov-2, to, be, of, and"
24775,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.114285714,"that, the, to, lineage"
24776,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.114285714,"the, cases, in, that"
24777,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.114285714,"is, the, and, of"
24778,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.114285714,"a, origin, and, is"
24779,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.114285714,"the, of, and, lineage"
24780,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.114285714,"the, of, with, consistent"
24781,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.114285714,"a, virus, from, the"
24782,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.114285714,"the, of, a, from"
24783,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.114285714,"the, presence, of, a"
24784,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.114285714,"he, from, the, of"
24785,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.114285714,"of, the, a, virus"
24786,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.114285714,"the, that, sars-cov-2, in"
24787,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.114285714,"in, a, an, animal"
24788,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.114285714,"a, in, their, and"
24789,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.114285714,"of, sars-cov-2, and, humans"
24790,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.114285714,"of, and, were, into, from, in, humans, to"
24791,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.114285714,"and, at, zoonotic, of, sars-cov-2, into, in, from"
24792,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.114285714,"from, into, and, jumps, to, of, sars-cov-2, in"
24793,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor",0.114285714,"sars-cov-2, to, a, progenitor"
24794,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.114285714,"to, the, have, in, of, that, animals, a"
24795,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.114285714,"the, for, first, to, a, that, this, as, receptor, human, by, of, coronavirus, at, its, an"
24796,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.114285714,"in, a, to, the, that, from, market, as"
24797,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.114285714,"from, as, it, to, the, that, in, a"
24798,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.114285714,"the, that, in, a, as, to, from, market"
24799,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.114285714,"the, is, that, virus, to, a, of, transmitted"
24800,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.114285714,"the, covid-19, is, of, to, a, virus, in"
24801,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.114285714,"live, are, a, this, in, the, that, to"
24802,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.114285714,"the, is, that, virus, a, of, and, it"
24803,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.114285714,"the, results, that, virus, found, in, animals, were"
24804,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.114285714,"a, in, an, animal"
24805,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.114285714,"a, that, covid-19, is"
24806,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.114285714,"the, a, of, that, most, likely, to, and"
24807,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.114285714,"the, a, was, and"
24808,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.114285714,"the, and, also, were"
24809,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.114285714,"that, seafood, the, virus"
24810,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.114285714,"the, were, huanan, seafood"
24811,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.114285714,"all, to, infection, and"
24812,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.114285714,"of, a, zoonotic, and"
24813,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.114285714,"and, to, zoonotic, of"
24814,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.114285714,"in, and, other, animals"
24815,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.114285714,"in, animals, and, can"
24816,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.114285714,"and, the, was, in"
24817,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.114285714,"the, natural, in, and"
24818,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.114285714,"from, to, and, animals"
24819,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.114285714,"that, the, was, a"
24820,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.114285714,"genome, to, the, covid-19"
24821,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.114285714,"the, of, intermediate, host"
24822,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.114285714,"the, animal, host, of"
24823,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.114285714,"of, to, the, was"
24824,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.114285714,"of, in, the, with"
24825,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.114285714,"a, study, the, in"
24826,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.114285714,"possible, a, of, the"
24827,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.114285714,"study, possible, in, with"
24828,"According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.114285714,"to, the, close, of"
24829,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.114285714,"in, the, of, a, that, were, to, and"
24830,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.114285714,"the, coronavirus, from, has"
24831,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.114285714,"the, virus, which, has"
24832,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.114285714,"the, to, identical, and"
24833,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.114285714,"and, the, be, that, was, sars-cov-2, from, a"
24834,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.114285714,"that, sars-cov-2, originated, bats"
24835,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","Bats have been reported as being the rich source of 

coronaviruses",0.114285714,"been, the, of, as"
24836,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.114285714,"sars-cov-2, has, have, the"
24837,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.114285714,"a, with, the, sars-cov-2"
24838,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.114285714,"sars-cov-2, from, a, to"
24839,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.114285714,"the, to, sars-cov-2, from"
24840,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.114285714,"the, has, coronavirus, from"
24841,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.114285714,"to, the, a, sars-cov-2"
24842,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.114285714,"of, the, that, by"
24843,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.114285714,"a, of, comparative, analysis"
24844,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.114285714,"to, bat, the, of"
24845,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.114285714,"of, the, to, and"
24846,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.114285714,"and, is, of, bat"
24847,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.114285714,"of, be, to, the"
24848,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.114285714,"of, to, and, the"
24849,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.114285714,"is, possible, of, the"
24850,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.114285714,"the, a, from, and"
24851,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.114285714,"the, virus, to, in"
24852,"this one jumped from bats origin  

into humans","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.114285714,"jumped, from, bats, humans"
24853,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.114285714,"the, most, to, covid-19"
24854,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.114285714,"to, the, zoonotic, of"
24855,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.114285714,"that, to, in, covid-19"
24856,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.114285714,"the, that, was, a"
24857,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.114285714,"in, the, natural, and"
24858,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.114285714,"to, in, humans, and"
24859,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.114285714,"the, natural, origin, and"
24860,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.114285714,"the, that, naturally, virus"
24861,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.114285714,"and, that, sars-cov, is"
24862,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.114285714,"in, to, and, the"
24863,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.114285714,"the, in, and, that"
24864,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.114285714,"to, the, that, of"
24865,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.114285714,"the, sequence, of, that"
24866,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.114285714,"the, from, animals, market"
24867,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.114285714,"the, from, market, in"
24868,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.114285714,"the, from, wild, animals"
24869,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.114285714,"were, the, and, also"
24870,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.114285714,"that, the, seafood, virus"
24871,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.114285714,"the, of, a, in, that, with, as, or, were, used, it, china"
24872,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.114285714,"the, that, from, be"
24873,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.114285714,"suggesting, might, be, the"
24874,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.114285714,"the, has, coronavirus, sars-cov-2"
24875,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.114285714,"of, to, the, bat"
24876,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.114285714,"the, of, close, to"
24877,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.114285714,"all, to, and, infection"
24878,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.114285714,"to, in, and, humans"
24879,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.114285714,"that, has, are, the"
24880,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.114285714,"the, that, has, bat"
24881,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.114285714,"the, been, human, from"
24882,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.114285714,"that, from, bat, it"
24883,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.114285714,"the, that, has, of"
24884,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.114285714,"the, of, that, from"
24885,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.114285714,"the, protein, in, of"
24886,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.114285714,"of, that, bats, sars-covs"
24887,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.114285714,"is, of, bat, and"
24888,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.114285714,"is, and, sars-cov, that"
24889,hese close genetic relations suggest that they all have their ecological origin in bat populations,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.114285714,"genetic, that, have, bat"
24890,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.114285714,"bats, is, and, on"
24891,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.114285714,"that, bats, likely, of"
24892,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.114285714,"has, bats, the, most"
24893,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.114285714,"the, virus, has, which"
24894,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.114285714,"the, covid-19, virus, in"
24895,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.114285714,"the, virus, has, in"
24896,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.114285714,"human, to, a, called"
24897,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.114285714,"that, a, to, from"
24898,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.114285714,"is, a, zoonotic, to"
24899,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.114285714,"a, the, virus, it"
24900,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.114285714,"a, virus, the, from"
24901,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.114285714,"the, from, to, animals"
24902,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.114285714,"the, are, from, bats"
24903,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.114285714,"of, is, to, the"
24904,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.114285714,"of, from, in, coronaviruses"
24905,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.114285714,"genetic, have, that, bat"
24906,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.114285714,"genetic, suggest, that, origin"
24907,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.114285714,"found, in, rhinolophus, and"
24908,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.114285714,"and, found, in, the"
24909,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.114285714,"been, the, human, from"
24910,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.114285714,"in, the, and, market"
24911,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.114285714,"virus, the, and, an"
24912,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.114285714,"is, a, and, origin"
24913,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.114285714,"a, sars-cov-2, that, and"
24914,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.114285714,"the, sars-cov-2, humans, from"
24915,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.114285714,"the, that, animal, is"
24916,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.114285714,"the, from, that, and"
24917,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.114285714,"that, is, the, and"
24918,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.114285714,"that, the, lineage, to"
24919,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.114285714,"and, of, lineage, the"
24920,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.114285714,"the, covid-19, genome, to"
24921,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.114285714,"of, the, genome, with"
24922,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.114285714,"the, as, well, in"
24923,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.114285714,"coronaviruses, the, to, and"
24924,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.114285714,"the, that, and, to"
24925,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.114285714,"that, are, the, to"
24926,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.114285714,"zoonotic, are, the, and"
24927,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.114285714,"a, of, and, the, with, as, or, intermediate"
24928,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.114285714,"indicated, that, of, sars-cov-2"
24929,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.114285714,"of, the, is, similar"
24930,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.114285714,"bat, has, of, with"
24931,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.114285714,"of, to, the, from, coronavirus, bat, novel, and, sars, genome, more, related"
24932,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.114285714,"that, has, to, and"
24933,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.114285714,"the, identity, of, and"
24934,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.114285714,"that, sars-cov-2, originated, from"
24935,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.114285714,"sars-cov-2, to, in, host"
24936,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.114285714,"is, between, and, the"
24937,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.114285714,"and, the, of, virus"
24938,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.114285714,"studies, that, to, from"
24939,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.114285714,"the, of, are, to"
24940,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.114285714,"sars-cov-2, bat, in, a"
24941,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.114285714,"that, in, a, from"
24942,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.114285714,"virus, is, that, from"
24943,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.114285714,"a, this, in, that"
24944,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.114285714,"bat, that, sars-cov-2, a"
24945,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.114285714,"that, sars-cov-2, a, bat"
24946,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.114285714,"the, with, a, sars-cov-2"
24947,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.114285714,"that, sars-cov-2, a, and"
24948,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.114285714,"with, genome, the, of"
24949,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.114285714,"of, genome, with, sars-cov-2"
24950,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.114285714,"that, sars-cov-2, the, with"
24951,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.114285714,"that, the, of, bat, in, viruses, a, to"
24952,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.114285714,"of, the, in, a, similar, to, sars-cov-2,, that"
24953,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.114285714,"and, sars-cov-2, are, other"
24954,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.114285714,"of, sars-cov-2, humans, and"
24955,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.114285714,"of, the, and, other"
24956,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.114285714,"animal, are, and, the"
24957,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.114285714,"the, of, sars-cov-2, animal"
24958,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.114285714,"in, a, coronavirus, that, coronaviruses, from, to, and"
24959,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.114285714,"the, likely, to, pangolin"
24960,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.114285714,"the, sars-cov-2, has, coronavirus"
24961,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.114285714,"the, sars-cov-2, a, from"
24962,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.114285714,"hypothesis, that, the, of"
24963,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.114285714,"a, of, to, the, virus, that, transmitted, is"
24964,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.114285714,"a, the, of, and, it, virus, that, is"
24965,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.114285714,"the, of, and, that, virus, a, to, humans."
24966,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.114285714,"at, the, of, with"
24967,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.114285714,"the, are, of, human"
24968,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.114285714,"a, hypothesis, that, the"
24969,"All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.114285714,"the, that, a, sars-cov-2"
24970,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.114285714,"the, hypothesis, of, a"
24971,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.114285714,"have, on, 8,, is"
24972,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.114285714,"bats, the, sars-cov-2, to"
24973,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.114285714,"the, of, that, at"
24974,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.114285714,"the, of, an, that"
24975,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.114285714,"that, origin, of, the"
24976,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.114285714,"sars-cov-2, and, pangolin, between"
24977,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.114285714,"of, have, furin, cleavage"
24978,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.114285714,"of, have, been, in"
24979,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.114285714,"the, in, for, of"
24980,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.114285714,"a, origin, of, sars-cov-2"
24981,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.114285714,"sars-cov-2, as, the, natural"
24982,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.114285714,"of, a, the, from"
24983,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.114285714,"and, the, from, a"
24984,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.114285714,"a, from, the, sars-cov-2"
24985,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.114285714,"the, of, origin, a"
24986,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.114285714,"a, of, from, sars-cov-2"
24987,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","this one jumped from bats origin  

into humans",0.114285714,"bats, jumped, humans, from"
24988,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.114285714,"was, the, to, a"
24989,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.114285714,"to, the, a, human"
24990,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.114285714,"to, by, was, the"
24991,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.114285714,"to, a, the, human"
24992,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.114285714,"the, to, a, animals"
24993,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.114285714,"the, to, was, transmitted"
24994,"S1/S2 cleavage sites of coronaviruses are frequently modi- 

fied by insertions or deletions (indels) during evolution",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.114285714,"of, coronaviruses, are, by"
24995,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.114285714,"presence, of, a, the"
24996,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.114285714,"a, zoonotic, of, and"
24997,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.114285714,"the, of, a, bat"
24998,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.114285714,"of, the, bat, and"
24999,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.114285714,"a, of, bat, in"
25000,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.114285714,"to, the, sars-cov-2, zoonotic"
25001,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.114285714,"the, of, and, wild"
25002,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.114285714,"sars-cov, sars-cov-2, to, a"
25003,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.114285714,"sars-cov-2, or, to, a"
25004,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.114285714,"has, genome, sars-cov-2, a"
25005,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.114285714,"sars-cov-2, to, a, genome"
25006,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.114285714,"the, sars-cov-2, in, with"
25007,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.114285714,"sars-cov-2, a, in, host"
25008,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.114285714,"the, were, with, in"
25009,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.114285714,"the, of, be, to"
25010,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.114285714,"the, to, human, a"
25011,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.114285714,"to, contact, be, the"
25012,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.114285714,"the, most, be, as"
25013,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.114285714,"the, been, to, sars-cov-2"
25014,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.114285714,"the, was, to, by"
25015,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.114285714,"sars-cov-2, virus, the, and"
25016,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.114285714,"the, in, that, sars-cov-2"
25017,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.114285714,"the, for, to, a, virus, that, with, this, and, human, in, of"
25018,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.114285714,"in, which, were, of"
25019,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.114285714,"of, indicated, that, sars-cov-2"
25020,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.114285714,"of, has, with, bat"
25021,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.114285714,"the, that, to, is"
25022,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.114285714,"the, sars-cov-2, to, is"
25023,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.114285714,"the, host, animal, of"
25024,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.114285714,"is, that, the, animal"
25025,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.114285714,"the, origin, of, a"
25026,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.114285714,"the, and, ratg13,, sequence"
25027,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.114285714,"the, sars-, cov-2, is"
25028,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.114285714,"the, of, sars-cov-2, pangolin-cov"
25029,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.114285714,"the, of, in, sars-cov-2"
25030,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","bats are also important reservoir species for a great 

range of coronaviruses",0.114285714,"bats, also, are, for"
25031,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","bats are also important reservoir species for a great 

range of coronaviruses",0.114285714,"are, species, of, bats"
25032,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.114285714,"the, sequence, ratg13,, and"
25033,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.114285714,"that, sequence, of, shares"
25034,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.114285714,"the, for, to, in"
25035,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.114285714,"sars-cov-2, with, the, in"
25036,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.114285714,"the, sars-cov-2, with, pangolin-cov"
25037,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.114285714,"and, a, the, of, with, or, as, intermediate"
25038,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.114285714,"the, as, a, species, of, that, hosts, and"
25039,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.114285714,"that, sars-cov-2, a, laboratory"
25040,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.114285714,"the, obtained, by, and, to, sars-cov-2, is, of"
25041,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.114285714,"a, to, the, from"
25042,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.114285714,"an, from, to, the"
25043,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.114285714,"the, from, intermediate, host"
25044,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.114285714,"the, an, very, to"
25045,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.114285714,"several, sars-cov-2, to, the"
25046,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.114285714,"and, the, to, in"
25047,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.114285714,"bat, coronavirus, to, in"
25048,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.114285714,"the, of, sars-cov-2, to, result, a, that, evidence"
25049,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.114285714,"coronaviruses, of, reservoir, bats"
25050,"Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.114285714,"to, a, sars-cov-2, progenitor"
25051,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.114285714,"in, a, of, to, the, virus, covid-19, is"
25052,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.114285714,"the, virus, covid-19, in"
25053,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.114285714,"the, of, whether, virus, a, in, or, to"
25054,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.114285714,"the, or, zoonotic, spillover, of, sars-cov-2, in, a"
25055,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.114285714,"the, and, for, of"
25056,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.114285714,"are, the, including, and"
25057,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.114285714,"most, in, the, are"
25058,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.114285714,"to, virus, and, the"
25059,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.114285714,"to, in, the, for"
25060,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.114285714,"discovered, virus, the, in"
25061,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.114285714,"the, related, to, for"
25062,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.114285714,"and, in, to, of"
25063,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.114285714,"the, of, bat, that, a, in, viruses, to"
25064,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.114285714,"the, of, that, viruses, in, a, multiple, to"
25065,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.114285714,"the, a, in, to, that, bat, of, but"
25066,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.114285714,"of, are, to, the"
25067,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.114285714,"are, to, the, of"
25068,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.114285714,"the, of, three, sars-cov-2"
25069,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.114285714,"the, of, sars-cov-2, by"
25070,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.114285714,"the, of, with, through"
25071,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","This suggests that the BANAL series may be able to directly infect  

humans.",0.114285714,"to, be, that, the"
25072,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","This suggests that the BANAL series may be able to directly infect  

humans.",0.114285714,"this, the, that, to"
25073,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.114285714,"he, of, the, from"
25074,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.114285714,"the, of, is, more"
25075,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.114285714,"a, of, at, the"
25076,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.114285714,"furin, cleavage, have, of"
25077,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.114285714,"have, the, a, of"
25078,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.114285714,"the, three, sars-cov-2, of"
25079,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.114285714,"the, covid-19, to, most"
25080,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.114285714,"the, to, virus, in"
25081,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.114285714,"the, most, closely, covid-19"
25082,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.114285714,"to, the, of, transmission, by, a, virus, with"
25083,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.114285714,"were, of, into, humans, from, in, and, to"
25084,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.114285714,"the, that, virus, to, a, of, and, humans."
25085,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.114285714,"whether, the, of, or, to, a, virus, in"
25086,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.114285714,"a, and, this, in, the, that, to, sars"
25087,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.114285714,"together,, this, to, that, the, of, and, evidence"
25088,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.114285714,"that, the, of, were, in, to, a, and"
25089,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.114285714,"a, virus, that, found, humans, infected, to, the"
25090,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.114285714,"in, the, of, identical, to, at, that, virus"
25091,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.114285714,"it, that, the, with, in, china, were, or, used, as, a, of"
25092,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.114285714,"the, genome, of, novel, coronavirus, from, to, bat, and, more, related, sars"
25093,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.114285714,"its, receptor, that, to, human, this, as, at, first, the, an, coronavirus, by, a, of, for"
25094,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.114285714,"is, to, a, zoonotic"
25095,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.114285714,"in, a, to, the, are, that, this, live"
25096,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.114285714,"a, that, in, this"
25097,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.114285714,"the, are, animal, and"
25098,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.114285714,"the, and, that, a, in, sars, this, to"
25099,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.114285714,"at, seafood, market, in, that, the, is, of"
25100,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.114285714,"at, zoonotic, of, sars-cov-2, into, from, in, and"
25101,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.114285714,"sars-cov-2, be, a, that, from, and, was, the"
25102,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.114285714,"the, of, zoonotic, spillover, sars-cov-2, or, a, in"
25103,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.114285714,"the, a, found, that, virus, infected, humans, to"
25104,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","expended to make the simple point 

that COVID-19 had a natural origin.",0.114285714,"the, that, to, covid-19"
25105,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","unnatural origin of SARS-CoV-2, but these people are 

simply wrong",0.114285714,"but, origin, of, sars-cov-2,"
25106,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.114285714,"in, rhinolophus, found, and"
25107,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.114285714,"a, and, their, in"
25108,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.114285714,"of, the, in, which"
25109,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.114285714,"the, of, to, natural"
25110,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.114285714,"the, of, and, unknown"
25111,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.114285714,"a, host, sars-cov-2, in"
25112,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.114285714,"zoonotic, an, animal, was"
25113,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.114285714,"the, virus, discovered, in"
25114,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.114285714,"in, a, the, with"
25115,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.114285714,"show, that, sars-cov-2, a"
25116,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.114285714,"evidence, to, sars-cov-2, result, a, of, the, that"
25117,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.114285714,"that, sars-cov-2, is, related"
25118,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.114285714,"that, of, sars-cov-2, coronavirus"
25119,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.114285714,"not, that, the, virus"
25120,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.114285714,"the, from, that, sars-"
25121,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.114285714,"virus, that, is, the"
25122,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.114285714,"the, is, sars-, cov-2"
25123,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.114285714,"the, reservoir, of, sars-cov-like"
25124,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.114285714,"the, is, of, possible"
25125,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.114285714,"the, that, an, of"
25126,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.114285714,"the, an, to, very"
25127,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.114285714,"that, the, of, multiple, in, viruses, a, to"
25128,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.114285714,"and, from, animals, to"
25129,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.114285714,"from, wild, animals, the"
25130,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.114285714,"from, animals, to, the"
25131,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.114285714,"that, the, and, from"
25132,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.114285714,"the, that, sars-, from"
25133,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.114285714,"evidence, and, that, the"
25134,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.114285714,"is, have, on, 8,"
25135,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.114285714,"that, the, of, sequence"
25136,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.114285714,"in, can, animals, and"
25137,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.114285714,"in, that, the, cases"
25138,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.114285714,"of, that, by, the"
25139,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.114285714,"have, been, in, of"
25140,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.114285714,"the, that, of, in"
25141,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.114285714,"of, in, which, the"
25142,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.114285714,"in, that, the, of"
25143,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.114285714,"is, the, and, for"
25144,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.114285714,"in, the, of, that, a, animals, have, to"
25145,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.114285714,"a, role, of, the, been, that, have, to"
25146,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.114285714,"the, in, results, found, animals, virus, that, were"
25147,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.114285714,"were, the, huanan, seafood"
25148,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.114285714,"in, the, with, of"
25149,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.114285714,"were, with, the, in"
25150,"with the first case being linked to  

a seafood market","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.114285714,"with, the, first, to"
25151,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.114285714,"is, the, to, and"
25152,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.114285714,"the, between, and, is"
25153,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.114285714,"to, the, be, contact"
25154,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.114285714,"the, to, is, bats"
25155,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.114285714,"the, to, and, bats"
25156,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.114285714,"the, to, from, is"
25157,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.114285714,"the, to, from, bats"
25158,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.114285714,"in, the, found, and"
25159,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.114285714,"was, the, of, a"
25160,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.114285714,"the, was, a, and"
25161,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.114285714,"the, in, market, and"
25162,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.114285714,"a, first, in, wildlife"
25163,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.114285714,"in, the, obtained, and, sars-cov-2, is, of, guangdong"
25164,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.114285714,"isolated, from, amino, acid, with, sars-cov-2, in, the"
25165,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.114285714,"of, which, were, in"
25166,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.114285714,"and, is, a, that"
25167,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.114285714,"the, and, is, of"
25168,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.114285714,"that, is, covid-19, a"
25169,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.114285714,"the, wild, and, of"
25170,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.114285714,"the, for, related, to"
25171,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.114285714,"have, from, reservoir, to, a, several, and, species"
25172,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.114285714,"most, that, a, likely, the, of, and, to"
25173,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.114285714,"a, of, species, and, that, the, as, hosts"
25174,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.114285714,"sars-cov-2, a, that, bat"
25175,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.114285714,"sars-cov-2, has, a, genome"
25176,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.114285714,"isolated, from, in, with, sars-cov-2, the, amino, acid"
25177,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.114285714,"on, and, is, bats"
25178,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.114285714,"in, bats, and, the"
25179,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.114285714,"many, such, coronaviruses, and"
25180,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.114285714,"of, a, virus, the"
25181,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.114285714,"the, that, virus, naturally"
25182,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.114285714,"the, for, of, zoonotic"
25183,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.114285714,"zoonotic, of, to, and"
25184,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.114285714,"and, the, virus, to"
25185,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.114285714,"the, of, to, zoonotic"
25186,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.114285714,"the, to, virus, and"
25187,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.114285714,"of, the, virus, and"
25188,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.114285714,"a, of, natural, origin"
25189,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.114285714,"a, comparative, analysis, of"
25190,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.114285714,"to, the, have, been, of, that, a, role"
25191,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.114285714,"the, are, most, in"
25192,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.114285714,"a, from, to, sars-cov-2"
25193,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.114285714,"it, that, from, bat"
25194,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.114285714,"in, a, first, wildlife"
25195,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.114285714,"data, that, sars-cov-2, to"
25196,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.114285714,"first, in, that, bat"
25197,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.114285714,"that, sars-cov-2, in, humans"
25198,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.114285714,"not, the, been, other"
25199,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.114285714,"and, that, have, not, from, the, was, of"
25200,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.114285714,"jumps, of, sars-cov-2, into, from, in, and, to"
25201,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.114285714,"the, that, in, a, as, it, to, from"
25202,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","S1/S2 cleavage sites of coronaviruses are frequently modi- 

fied by insertions or deletions (indels) during evolution",0.114285714,"are, of, by, coronaviruses"
25203,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.114285714,"was, an, animal, zoonotic"
25204,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.114285714,"the, likely, for, as"
25205,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.114285714,"that, sars-cov-2, has, been"
25206,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.114285714,"of, the, hypothesis, a"
25207,zoonotic origins of SARS-CoV-2 by natural evolution,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.114285714,"of, sars-cov-2, by, natural"
25208,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.114285714,"identical, to, was, from"
25209,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.114285714,"sars-cov-2, from, and, to"
25210,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.114285714,"are, and, that, to"
25211,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.114285714,"to, that, of, bats, and, are, more, sars-cov-2"
25212,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.114285714,"of, sars-cov-2, genome, with"
25213,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.114285714,"of, sars-cov-2, bat, ratg13"
25214,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.114285714,"the, from, that, be"
25215,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.114285714,"as, the, be, most"
25216,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.114285714,"sars-cov-2, genetic, with, other"
25217,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.114285714,"consistent, with, of, the"
25218,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.114285714,"of, natural, to, the"
25219,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.114285714,"of, bat, sars-cov-2, ratg13"
25220,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.114285714,"we, sars-cov-2, bat, ratg13"
25221,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.114285714,"bat, of, sars-cov-2, and"
25222,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.114285714,"to, the, bats,, sars-cov-2"
25223,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.114285714,"to, the, hypothesis, that, sars-cov-2, of, natural, origin"
25224,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.114285714,"the, of, and, that, together,, this, evidence, to"
25225,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.114285714,"sars-cov-2, and, bats, pangolins"
25226,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.114285714,"that, sars-cov-2, are, and"
25227,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.114285714,"the, is, that, of, seafood, market, in, at"
25228,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.114285714,"are, to, the, that"
25229,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.114285714,"as, the, for, likely"
25230,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.114285714,"many, bat, to, and"
25231,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.114285714,"important, of, and, a, which, to, in, human"
25232,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.114285714,"study, in, possible, with"
25233,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.114285714,"the, to, as, sars-cov-2"
25234,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.114285714,"viruses, in, a, of"
25235,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.114285714,"the, sars-cov-2, of, is"
25236,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.114285714,"be, based, on, the, and, viruses, to, in"
25237,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.114285714,"that, sars-cov-2, of, coronavirus"
25238,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.114285714,"that, sars-cov-2, likely, from"
25239,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.114285714,"the, of, sars-cov-2, to, obtained, is, and, by"
25240,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.114285714,"of, the, sars-cov-2, in, obtained, is, guangdong, and"
25241,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.114285714,"sars-cov-2, with, thus, that"
25242,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.114285714,"the, that, sars-cov-2, origin"
25243,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.114285714,"has, that, sars-cov-2, the"
25244,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.114285714,"the, sars-cov-2, with, that"
25245,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.114285714,"sars-cov-2, bat, ratg13, the"
25246,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.114285714,"the, of, sars-cov-2, bats"
25247,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.114285714,"that, likely, bats, of"
25248,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.114285714,"of, bats, sars-cov-2, the"
25249,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.114285714,"the, of, that, this"
25250,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.114285714,"that, the, sars-cov-2, than"
25251,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.114285714,"and, bat, of, origin"
25252,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.114285714,"sars-cov-2, that, originated, bats"
25253,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.114285714,"bats, are, more, to, that, of, sars-cov-2, and"
25254,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.114285714,"the, pangolin, to, likely"
25255,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.114285714,"to, that, similarity, and"
25256,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.114285714,"and, that, has, to"
25257,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.114285714,"and, the, identity, of"
25258,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.114285714,"identity, with, the, sars-cov-2"
25259,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.114285714,"the, of, identity, and"
25260,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.114285714,"the, of, identity, sars-cov-2"
25261,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.114285714,"of, the, pangolin-cov, sars-cov-2"
25262,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.114285714,"the, sars-cov-2, by, of"
25263,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.114285714,"the, for, of, sars-cov-2"
25264,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.114285714,"the, evidence, that, and"
25265,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.114285714,"the, a, from, bats,"
25266,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.114285714,"of, the, have, a"
25267,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.114285714,"identical, the, to, in"
25268,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.114285714,"sars-cov-2, in, and, to"
25269,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.114285714,"the, and, in, sars-cov-2"
25270,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.114285714,"the, sars-cov-2, to, in"
25271,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.114285714,"sars-cov-2, to, in, the"
25272,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.114285714,"the, sars-cov-2, are, to"
25273,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.114285714,"virus, and, natural, of"
25274,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.114285714,"in, that, of, the"
25275,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.114285714,"the, was, transmitted, to"
25276,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.114285714,"the, identity, of, sars-cov-2"
25277,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.114285714,"that, the, low, sars-cov-2"
25278,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.114285714,"in, the, of, at, that, virus, identical, to"
25279,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.114285714,"this, the, sars-cov-2, for"
25280,"unnatural origin of SARS-CoV-2, but these people are 

simply wrong","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.114285714,"origin, of, sars-cov-2,, but"
25281,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.114285714,"to, be, sars-cov-2,, that, the, of, bats, sars-cov-2"
25282,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.114285714,"a, of, with, by, the, transmission, to, virus"
25283,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.114285714,"was, that, the, bat"
25284,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.114285714,"in, the, that, as"
25285,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.114285714,"the, that, in, was"
25286,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.114285714,"the, that, bat, in"
25287,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.114285714,"that, the, in, bat"
25288,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.114285714,"that, bat, first, in"
25289,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.114285714,"studies, that, from, to"
25290,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.114285714,"that, to, sars-cov-2, from"
25291,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.114285714,"of, unknown, and, the"
25292,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.114285714,"of, sars-cov-2, and, bat"
25293,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.114285714,"the, sars-cov-2, a, cov"
25294,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.114285714,"a, the, virus, and"
25295,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.114285714,"the, virus, a, and"
25296,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.114285714,"the, suggesting, might, be"
25297,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.114285714,"the, virus, an, and"
25298,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.114285714,"virus, and, the, sars-cov-2"
25299,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.114285714,"a, virus, the, sars-cov-2"
25300,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.114285714,"the, sars-cov-2, virus, and"
25301,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.114285714,"a, at, the, of, in, virus, that, is"
25302,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.114285714,"the, of, is, for, in, a, virus, that"
25303,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.114285714,"coronaviruses, of, a, in"
25304,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.114285714,"sars-cov-2, in, of, bat"
25305,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.114285714,"of, in, coronaviruses, from"
25306,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.114285714,"of, sars-cov-2, a, from"
25307,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.114285714,"of, a, in, bat"
25308,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.114285714,"are, zoonotic, the, and"
25309,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.114285714,"and, a, of, in, which, important, to, human"
25310,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.114285714,"the, of, that, a, in, similar, to, sars-cov-2,"
25311,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.114285714,"the, a, resulting, in, to, that, of, sars-cov-2,"
25312,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.114285714,"to, that, sars-cov-2, the, bats, be, of, sars-cov-2,"
25313,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.114285714,"that, the, of, bat, in, but, a, to"
25314,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.114285714,"of, the, resulting, in, a, to, sars-cov-2,, that"
25315,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.114285714,"is, more, the, of"
25316,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.114285714,"viruses, to, based, on, the, in, and, be"
25317,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.114285714,"to, the, high, sars-cov-2"
25318,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.114285714,"sars-cov-2, the, bat, ratg13"
25319,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.114285714,"a, is, the, that"
25320,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.114285714,"a, that, the, sars-cov-2"
25321,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.114285714,"the, low, that, sars-cov-2"
25322,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.11409396,"for, and, an, with, from, to, samples, at, the, market, in, of, collected, a, tested, positive, animal"
25323,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.11409396,"the, market, that, officials, in, for, of, were, to, by, and, public, health, with, a, not, an"
25324,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.11409396,"a, of, the, market, at, animal, and, in, an, to, with, samples, for, from, tested, positive, collected"
25325,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.11409396,"a, of, the, market, public, health, and, were, by, officials, in, an, to, with, for, that, not"
25326,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.114035088,"in, the, of, sars, was, at, that, to, and, more, closely, related, than"
25327,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.114035088,"the, that, was, to, more, closely, related, sars, in, than, of, and, at"
25328,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.114035088,"a, study, genome, from, in, that, the, to, of, were, found, present, bats"
25329,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.114035088,"to, the, bats, were, a, in, of, study, from, that, present, genome, found"
25330,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.113924051,"the, virus, have, human, an, in, or, to, and"
25331,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.113924051,"and, that, the, novel, covid-19, virus, has, to, of"
25332,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.113924051,"a, in, that, the, virus, is, to, of, bats"
25333,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.113924051,"the, huanan, that, of, cases, were, to, and, covid-19"
25334,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.113924051,"that, the, of, covid-19, in, same, as, a, to"
25335,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.113924051,"the, is, that, of, first, covid-19, are, market, in"
25336,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.113924051,"the, is, that, of, and, in, but, environmental, at"
25337,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.113924051,"the, of, an, was, a, outbreak, that, to, and"
25338,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.113924051,"with, wuhan, the, huanan, market, in, early, of, january"
25339,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.113924051,"that, conserved, the, sars-cov-2, to, suggesting, by, of, and"
25340,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.113924051,"the, of, which, to, in, and, animals, virus, was"
25341,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.113924051,"with, the, and, that, sars-cov-2, of, bat, cov, as"
25342,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.113924051,"to, human, virus, have, or, in, an, and, the"
25343,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.113924051,"or, the, could, infected, to, and, in, been, may"
25344,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.113924051,"the, of, and, that, from, sequence, sars, as, to"
25345,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.113924051,"from, such, as, and, to, was, the, of, that"
25346,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.113924051,"of, covid-19, has, to, novel, virus, that, and, the"
25347,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.113924051,"a, of, in, that, for, with, the, to, virus"
25348,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.113924051,"in, a, of, to, the, that, covid-19, same, as"
25349,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.113924051,"the, of, closely, in, a, to, that, same, genetic"
25350,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.113924051,"as, multiple, to, the, of, that, in, a, infect"
25351,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.113924051,"that, the, of, in, same, closely, a, to, genetic"
25352,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.113924051,"in, the, of, virus, for, to, that, with, a"
25353,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.113924051,"the, sequence, of, that, from, to, as, and, sars"
25354,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.113924051,"that, a, was, the, of, outbreak, and, to, an"
25355,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.113924051,"of, in, the, huanan, market, with, wuhan, early, january"
25356,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.113924051,"of, the, covid-19, cases, were, to, huanan, and, that"
25357,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.113924051,"in, of, the, are, that, covid-19, first, is, market"
25358,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.113924051,"at, the, of, and, environmental, in, that, but, is"
25359,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.113924051,"the, could, been, in, or, infected, to, and, may"
25360,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.113924051,"in, animals, to, of, the, virus, which, and, was"
25361,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.113924051,"the, of, that, from, was, to, such, as, and"
25362,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.113924051,"that, the, of, multiple, in, as, infect, a, to"
25363,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.113924051,"the, of, and, conserved, suggesting, that, sars-cov-2, to, by"
25364,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.113924051,"bats, a, the, of, is, virus, in, that, to"
25365,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.113924051,"sars-, cov-2, the, sarbecovirus, sub-genus, of, and, as, are"
25366,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.113924051,"cov, with, bat, that, the, of, as, sars-cov-2, and"
25367,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.113924051,"of, the, sub-genus, and, are, sarbecovirus, sars-, cov-2, as"
25368,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.113821138,"the, from, and, were, in, their, by, of, a, which, we, that, at, least"
25369,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.113821138,"a, of, the, from, we, by, that, and, at, least, in, which, were, their"
25370,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.113636364,"sars-cov-2, to, a, bat, sars-cov"
25371,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.113636364,"a, to, in, human, and"
25372,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.113636364,"human, in, which, other, and"
25373,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.113636364,"to, a, in, human, viral"
25374,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.113636364,"sars-cov-2, a, bat, to, in"
25375,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.113636364,"two, viruses, the, in, from"
25376,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.113636364,"that, bats, more, of, than"
25377,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.113636364,"to, have, and, sars-cov, bat"
25378,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.113636364,"., in, to, genetic, and"
25379,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.113636364,"is, sars-cov-2, virus, its, in"
25380,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.113636364,"in, to, sars-cov-2, whole, genome"
25381,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.113636364,"to, in, more, sars-cov-2, than"
25382,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.113636364,"the, of, are, in, also"
25383,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.113636364,"bat, have, to, sars-cov, and"
25384,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.113636364,"the, virus, to, and, sars-cov"
25385,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.113636364,"it, is, sars-cov-2, of, a"
25386,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.113636364,"sars-cov-2, of, to, would, have, that, genetically, engineer, fingerprints, the"
25387,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.113636364,"sars-cov-2, the, fingerprints, of, that, have, to, engineer, would, genetically"
25388,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.113636364,"virus, is, sars-cov-2, in, its"
25389,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.113636364,"t, that, sars-cov-2, in, before"
25390,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.113636364,"that, the, of, to, bat"
25391,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.113636364,"the, to, that, human, and"
25392,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.113636364,"the, that, sars-cov-2, to, bat"
25393,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.113636364,"sars-cov, sars-cov-2, to, bat, a"
25394,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.113636364,"the, of, bat, that, to"
25395,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.113636364,"that, the, bat, was, of"
25396,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.113636364,"the, of, identity, sars-cov-2, genome"
25397,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.113636364,"the, is, of, a, to"
25398,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.113636364,"the, is, it, to, of"
25399,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.113636364,"and, of, genome, virus, bat"
25400,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.113636364,"sars-cov-2, the, covid-19, sequence, identity"
25401,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.113636364,"that, might, and, the, virus"
25402,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.113636364,"of, closer, to, the, in"
25403,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.113636364,"in, is, the, and, sars-cov-2"
25404,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.113636364,"have, that, the, of, to"
25405,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.113636364,"has, that, bats, the, of"
25406,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.113636364,"the, that, in, a, as"
25407,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.113636364,"a, that, bats, the, as"
25408,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.113636364,"the, that, a, of, has"
25409,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.113636364,"more, than, bats, of, and"
25410,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.113636364,"the, are, known, and, of"
25411,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.113636364,"have, been, other, of, as"
25412,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.113636364,"the, bats, are, more, than"
25413,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.113636364,"into, as, and, to, for, the, of, that, in, a"
25414,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.113636364,"human, and, to, in, a"
25415,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.113636364,"the, and, that, to, human"
25416,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.113636364,"is, the, to, was, in"
25417,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.113636364,"the, that, in, a, to"
25418,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.113636364,"the, to, in, a, bats,, is, was, that, virus, and"
25419,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.113636364,"the, and, is, a, to"
25420,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.113636364,"to, that, the, and, is"
25421,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.113636364,"the, of, sars-cov-2, from, bats"
25422,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.113636364,"phylogenetic, sars-cov-2, the, of, to"
25423,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.113636364,"and, to, of, the, a"
25424,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.113636364,"to, the, sars-cov-2, and, an"
25425,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.113636364,"the, a, and, to, of"
25426,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.113636364,"that, has, and, are, the"
25427,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.113636364,"and, that, the, has, of"
25428,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.113636364,"bats, are, of, by, the"
25429,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.113636364,"the, that, are, most, and"
25430,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.113636364,"the, of, bats, and, are"
25431,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.113636364,"disease, and, from, animals, to"
25432,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.113636364,"that, the, species, and, from"
25433,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.113636364,"the, natural, as, from, and"
25434,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.113636364,"the, covid-19, sequence, identity, sars-cov-2"
25435,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.113636364,"at, only, the, with, sars-cov-2"
25436,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.113636364,"is, the, to, in, was"
25437,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.113636364,"the, to, which, from, is"
25438,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.113636364,"with, the, a, from, bats,"
25439,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.113636364,"sars-cov-2, the, of, bat, in"
25440,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.113636364,"in, the, of, sars-cov-2, is"
25441,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.113636364,"the, to, that, with, of"
25442,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.113636364,"that, of, are, the, for"
25443,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.113636364,"from, the, has, identified, sars-cov-2"
25444,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.113636364,"bats, pangolins, be, the, sars-cov-2"
25445,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.113636364,"of, from, in, identified, sars-cov-2"
25446,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.113636364,"a, and, which, in, the"
25447,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.113636364,"a, which, the, in, by"
25448,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.113636364,"who, that, the, a, was"
25449,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.113636364,"the, that, was, a, not"
25450,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.113636364,"sars-cov-2, from, are, to, and"
25451,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.113636364,"that, the, of, to, a"
25452,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.113636364,"the, of, to, sars-cov-2, that"
25453,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.113636364,"has, that, and, are, the"
25454,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.113636364,"the, nucleotide, and, sars-cov-2, genome"
25455,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.113636364,"the, that, sars-cov-2, are, genome"
25456,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.113636364,"was, that, the, of, bat"
25457,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.113636364,"that, the, and, bat, at"
25458,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.113636364,"pangolins, from, and, of, sars-cov-2"
25459,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.113636364,"the, that, sars-cov-2, from, a"
25460,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.113636364,"that, the, from, a, to"
25461,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.113636364,"the, sars-cov-2, humans, from, of"
25462,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.113636364,"are, the, known, of, and"
25463,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.113636364,"of, to, the, market, that"
25464,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.113636364,"sars-cov-2, that, through, to, the"
25465,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.113636364,"sars-cov-2, and, to, the, that"
25466,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.113636364,"the, and, that, in, animal"
25467,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.113636364,"into, the, that, in, sars-cov-2"
25468,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.113636364,"and, with, at, the, huanan, market, in, early, of, animal"
25469,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.113636364,"we, to, the, that, in"
25470,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.113636364,"this, of, the, market, in"
25471,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.113636364,"and, a, at, the, is"
25472,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.113636364,"this, is, and, the, in"
25473,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.113636364,"in, the, origin, of, and"
25474,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.113636364,"in, the, of, is, at"
25475,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.113636364,"the, human, in, to, were"
25476,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.113636364,"the, likely, reservoirs, in, and"
25477,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.113636364,"into, from, in, to, and"
25478,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.113636364,"sars-cov-2, at, of, and, to"
25479,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.113636364,"the, of, as, a, and"
25480,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.113636364,"the, that, all, sars-cov-2, a"
25481,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.113636364,"the, was, and, that, of"
25482,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.113636364,"that, the, of, and, more"
25483,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.113636364,"in, is, that, sars-cov-2, a"
25484,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.113636364,"is, that, sars-cov-2, a, or"
25485,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.113636364,"a, sars-cov-2, in, their, is"
25486,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.113636364,"in, the, that, as, a"
25487,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.113636364,"the, from, in, market, to"
25488,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.113636364,"the, that, a, as, to"
25489,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.113636364,"the, to, a, as, with, on, was, that, virus, and"
25490,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.113636364,"the, that, a, virus, has"
25491,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.113636364,"that, the, also, and, is"
25492,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.113636364,"the, and, virus, is, that"
25493,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.113636364,"that, of, a, and, to"
25494,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.113636364,"that, all, to, a, and"
25495,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.113636364,"human, and, in, which, other"
25496,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.113636364,"and, in, the, of, natural"
25497,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.113636364,"animals, from, disease, to, and"
25498,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.113636364,"that, the, covid-19, and, first"
25499,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.113636364,"studies, genome, the, bat, and"
25500,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.113636364,"and, high, to, the, of"
25501,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.113636364,"the, closer, to, in, of"
25502,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.113636364,"of, to, that, the, virus"
25503,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.113636364,"the, indicate, that, virus, than"
25504,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.113636364,"the, identical, to, that, of"
25505,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.113636364,"the, of, to, that, from"
25506,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.113636364,"the, virus, from, to, and"
25507,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.113636364,"as, to, the, be, a"
25508,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.113636364,"coronavirus, from, to, have, been"
25509,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.113636364,"protein, the, of, with, sars-cov-2"
25510,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.113636364,"to, is, of, the, and"
25511,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.113636364,"the, of, to, human, is"
25512,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.113636364,"is, that, the, was, of"
25513,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.113636364,"of, was, based, on, analysis"
25514,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.113636364,"the, to, from, bats, in"
25515,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.113636364,"the, a, was, and, to"
25516,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.113636364,"the, from, to, a, and"
25517,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.113636364,"to, a, was, from, in"
25518,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.113636364,"at, that, the, virus, a"
25519,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.113636364,"a, that, the, and, animals"
25520,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.113636364,"., in, genetic, to, and"
25521,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.113636364,"the, in, bats, is, and"
25522,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.113636364,"the, of, that, is, was"
25523,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.113636364,"that, the, virus, at, a"
25524,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.113636364,"the, was, a, at, of"
25525,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.113636364,"virus, is, at, the, of"
25526,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.113636364,"who, that, the, and, to"
25527,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.113636364,"the, likely, more, in, and"
25528,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.113636364,"to, the, and, sars-cov, virus"
25529,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.113636364,"the, animal, and, that, in"
25530,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.113636364,"that, the, is, origin, animal"
25531,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.113636364,"of, the, outbreak, in, wuhan,"
25532,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.113636364,"the, of, is, to, be"
25533,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.113636364,"the, of, bats, because, and"
25534,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.113636364,"virus, is, the, sequence, of"
25535,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.113636364,"to, and, of, is, that"
25536,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.113636364,"is, or, the, natural, reservoir"
25537,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.113636364,"or, on, the, be, to, and, raccoon, dog, sars-cov, may"
25538,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.113636364,"could, be, to, the, that"
25539,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.113636364,"analysis, that, the, to, bat"
25540,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.113636364,"that, could, be, possible, sars-cov-2"
25541,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.113636364,"is, the, bat, to, be"
25542,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.113636364,"that, the, may, a, of"
25543,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.113636364,"a, the, of, possible, with"
25544,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.113636364,"is, the, be, of, to"
25545,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.113636364,"genome, to, be, the, of"
25546,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.113636364,"the, genome, that, to, of"
25547,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.113636364,"genetic, of, the, several, have"
25548,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.113636364,"that, of, and, likely, bats"
25549,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.113636364,"the, sars-cov-2, closely, related, to"
25550,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.113636364,"of, the, isolated, from, in"
25551,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.113636364,"the, of, isolated, from, in"
25552,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.113636364,"in, of, to, coronaviruses, the, from, bats, sars, closely, related"
25553,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.113636364,"in, to, the, of, is"
25554,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.113636364,"into, from, in, and, to"
25555,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.113636364,"the, in, to, from, market"
25556,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.113636364,"to, virus, from, and, the"
25557,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.113636364,"the, virus, to, and, been"
25558,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.113636364,"the, or, to, virus, in"
25559,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.113636364,"animal, and, in, the, to"
25560,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.113636364,"to, have, in, the, or"
25561,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.113636364,"the, virus, been, in, animal"
25562,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.113636364,"and, that, sars-cov-2, is, animal"
25563,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.113636364,"is, and, that, sars-cov-2, animal"
25564,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.113636364,"from, that, and, the, species"
25565,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.113636364,"sars-cov-2, the, and, that, is"
25566,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.113636364,"is, the, that, from, and"
25567,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.113636364,"the, of, and, that, to"
25568,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.113636364,"the, of, showed, identity, was"
25569,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.113636364,"with, the, of, covid-19, virus"
25570,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.113636364,"of, the, in, was, by"
25571,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.113636364,"this, the, covid-19, of, and"
25572,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.113636364,"the, of, between, from, and"
25573,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.113636364,"the, virus, bats, to, from"
25574,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.113636364,"the, genome, of, to, be"
25575,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.113636364,"virus, with, the, covid-19, of"
25576,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.113636364,"the, from, to, of, with"
25577,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.113636364,"virus, from, with, the, of"
25578,"Bats are natural hosts of many of the known  

coronaviruses","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.113636364,"bats, natural, of, the, coronaviruses"
25579,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.113636364,"was, from, that, to, and"
25580,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.113636364,"has, that, and, the, of"
25581,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.113636364,"the, covid-19, and, of, to"
25582,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.113636364,"and, the, that, to, sars"
25583,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.113636364,"has, identity, bat, that, and"
25584,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.113636364,"the, of, that, virus, has"
25585,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.113636364,"a, that, the, sars-cov-2, from"
25586,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.113636364,"that, a, sars-cov-2, the, through"
25587,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.113636364,"and, that, a, natural, the"
25588,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.113636364,"a, analysis, that, the, and"
25589,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.113636364,"the, and, that, sars-cov-2, a"
25590,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.113636364,"and, that, the, bat, at"
25591,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.113636364,"a, to, that, the, from"
25592,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.113636364,"that, were, in, and, china"
25593,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.113636364,"a, patients, at, in, china"
25594,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.113636364,"the, are, of, that, to"
25595,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.113636364,"the, to, identical, that, of"
25596,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.113636364,"of, the, sars-cov-2, a, virus"
25597,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.113636364,"sars-cov-2, a, that, with, the"
25598,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.113636364,"of, the, that, sars-cov-2, part"
25599,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.113636364,"he, of, sars-cov-2, that, the"
25600,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Bats are natural hosts of many of the known  

coronaviruses",0.113636364,"coronaviruses, the, bats, natural, of"
25601,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.113636364,"the, identified, sars-cov-2, has, from"
25602,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.113636364,"coronavirus, similarity, which, sars-cov-2, the"
25603,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.113636364,"the, from, sars-cov-2, a, coronavirus"
25604,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.113636364,"similarity, a, sequence, which, from"
25605,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.113636364,"the, to, after, a, is"
25606,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.113636364,"that, a, to, it, evolved"
25607,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.113636364,"a, was, that, the, to"
25608,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.113636364,"the, of, genome, to, that"
25609,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.113636364,"a, to, in, the, that"
25610,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.113636364,"the, that, a, in, coronavirus"
25611,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.113636364,"in, of, genome, similar, to"
25612,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.113636364,"the, of, human, are, with"
25613,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.113636364,"that, to, could, be, the"
25614,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.113636364,"our, the, of, sars-cov-2, is"
25615,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.113636364,"was, the, sars-cov-2, and, to"
25616,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.113636364,"the, of, sars-cov-2, was, to"
25617,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.113636364,"of, to, the, bat, was"
25618,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.113636364,"the, of, animal, that, at"
25619,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.113636364,"of, that, the, origin, animal"
25620,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.113636364,"of, the, and, that, was"
25621,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.113636364,"have, been, as, of, other"
25622,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.113636364,"of, the, in, sites, viruses"
25623,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.113636364,"of, in, the, for, viruses"
25624,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.113636364,"from, as, natural, and, the"
25625,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.113636364,"the, a, as, of, and"
25626,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.113636364,"of, the, from, between, and"
25627,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.113636364,"the, of, a, and, as"
25628,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.113636364,"and, the, origin, sars-cov-2, ratg13"
25629,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.113636364,"bats, are, the, of, by"
25630,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.113636364,"the, of, in, to, and"
25631,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.113636364,"the, with, a, from, bats,"
25632,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.113636364,"the, and, bats, because, of"
25633,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.113636364,"the, of, with, its, natural"
25634,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.113636364,"cov, sars-cov-2, with, 99%, similarity"
25635,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.113636364,"the, a, as, to, spillover"
25636,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.113636364,"to, be, a, the, as"
25637,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.113636364,"the, of, spillover, to, a"
25638,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.113636364,"the, of, a, spillover, to"
25639,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.113636364,"a, the, spillover, to, epidemic"
25640,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.113636364,"to, the, most, of, be"
25641,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.113636364,"the, is, to, that, of"
25642,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.113636364,"the, covid-19, is, of, to"
25643,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.113636364,"sars-cov-2, is, to, the, or"
25644,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.113636364,"the, that, sars-cov-2, into, in"
25645,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.113636364,"has, been, that, sars-cov-2, in"
25646,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.113636364,"the, genome, of, sars-cov-2, identity"
25647,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.113636364,"sars-cov-2, nucleotide, and, the, genome"
25648,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.113636364,"the, of, identity, and, in"
25649,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.113636364,"the, sars-cov-2, with, of, and"
25650,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.113636364,"the, of, identity, sars-cov-2, from"
25651,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.113636364,"that, has, in, with, of"
25652,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.113636364,"a, in, that, sars-cov-2, research"
25653,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.113636364,"to, sars-cov-2, the, that, is"
25654,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.113636364,"is, the, same, sars-cov-2, that"
25655,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.113636364,"sars-cov-2, to, an, and, the"
25656,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.113636364,"with, the, protein, of, sars-cov-2"
25657,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.113636364,"et, of, sars-cov-2, at, the"
25658,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.113636364,"human, to, in, a, viral"
25659,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.113636364,"the, due, to, a, in"
25660,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.113636364,"that, to, sars-cov-2, in, and"
25661,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.113636364,"and, was, in, caused, the"
25662,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.113636364,"the, a, from, as, intermediate"
25663,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.113636364,"who, a, that, the, was"
25664,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.113636364,"who, the, to, that, and"
25665,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.113636364,"the, evidence, that, to, and"
25666,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.113636364,"were, human, in, to, the"
25667,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.113636364,"that, the, in, intermediate, of"
25668,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.113636364,"intermediate, host, was, in, the"
25669,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.113636364,"that, the, of, this, from"
25670,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.113636364,"that, the, of, in, market"
25671,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.113636364,"of, the, market, in, that"
25672,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.113636364,"in, the, of, sars-cov-2, that"
25673,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.113636364,"the, virus, in, or, to"
25674,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.113636364,"to, the, of, a, spillover"
25675,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.113636364,"due, to, a, in, the"
25676,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.113636364,"a, virus, the, sars-cov-2, in"
25677,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.113636364,"the, sars-cov-2, of, virus, to"
25678,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.113636364,"the, likely, in, and, reservoirs"
25679,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.113636364,"the, more, likely, in, and"
25680,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.113636364,"of, and, the, bats, viruses"
25681,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.113636364,"and, of, the, for, viruses"
25682,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.113636364,"of, bats, the, as, horseshoe"
25683,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.113636364,"and, of, the, most, likely"
25684,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.113636364,"that, and, are, the, most"
25685,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.113636364,"to, sars-cov-2, that, and, the"
25686,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.113636364,"to, that, the, most, and"
25687,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.113636364,"sars-cov-2, to, in, the, bat"
25688,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.113636364,"and, were, to, in, the"
25689,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.113636364,"the, and, of, to, bat"
25690,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.113636364,"this, a, the, of, and"
25691,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.113636364,"this, bat, is, the, cluster, with, that, bats, are, for"
25692,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.113636364,"with, sars-cov-2, a, common, ancestor"
25693,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.113636364,"sars-cov-2, to, have, with, which"
25694,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.113636364,"of, sars-cov-2, to, a, with"
25695,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.113636364,"the, coronavirus, which, similarity, sars-cov-2"
25696,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.113636364,"is, similar, to, the, bat"
25697,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.113636364,"to, sars-cov-2, in, whole, genome"
25698,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.113636364,"viruses, of, the, sars-cov-2, their"
25699,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.113636364,"the, of, to, is, and"
25700,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.113636364,"the, of, to, that, have"
25701,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.113636364,"have, the, of, to, that"
25702,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.113636364,"the, of, that, to, rbd"
25703,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.113636364,"is, a, and, at, the"
25704,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.113636364,"of, the, virus, to, bat"
25705,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.113636364,"sars-cov-2, the, in, related, is"
25706,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.113636364,"is, to, the, pandemic., be"
25707,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.113636364,"the, and, sars-cov-2, is, in"
25708,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.113636364,"the, first, covid-19, and, that"
25709,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.113636364,"to, the, with, a, from"
25710,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.113636364,"at, the, was, of, a"
25711,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.113636364,"in, the, and, that, of, samples, were, to, taken, from"
25712,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.113636364,"the, of, sars, in, closely, related, to, coronaviruses, from, bats"
25713,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.113636364,"a, recent, of, bat, from, small, in, china, identified, including"
25714,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.113636364,"animal, at, markets, are, a, and, this, in, the, that"
25715,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.113636364,"a, is, the, to, that, in, bats,, virus, and, was"
25716,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.113636364,"on, the, virus, was, as, a, that, with, and, to"
25717,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.113636364,"the, of, animal, with, and, early, huanan, market, at, in"
25718,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.113636364,"the, of, is, to, a"
25719,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.113636364,"and, the, covid-19, to, of"
25720,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.113636364,"is, the, of, to, covid-19"
25721,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.113636364,"the, to, covid-19, a, is"
25722,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.113636364,"and, that, the, to, sars"
25723,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.113636364,"to, the, epidemic, a, spillover"
25724,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.113636364,"this, that, in, the, a, at, and, animal, markets, are"
25725,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.113636364,"the, that, at, and, to"
25726,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.113636364,"the, are, also, in, of"
25727,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.113636364,"human, with, are, the, of"
25728,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.113636364,"in, the, of, that, samples, taken, from, were, to, and"
25729,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.113636364,"with, the, sars-cov-2, is, to"
25730,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.113636364,"through, the, that, to, sars-cov-2"
25731,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.113636364,"that, and, in, were, china"
25732,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.113636364,"that, to, and, in, sars-cov-2"
25733,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.113636364,"in, pangolins, to, that, sars-cov-2"
25734,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.113636364,"found, that, sars-cov-2, to, and"
25735,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.113636364,"the, reservoirs, of, and, viruses"
25736,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.113636364,"of, to, the, in, which"
25737,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.113636364,"a, in, sars-cov-2, animal, or"
25738,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.113636364,"sars-cov-2, a, virus, that, the"
25739,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.113636364,"the, sars-cov-2, a, virus, in"
25740,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.113636364,"the, that, virus, in, with"
25741,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.113636364,"sars-cov-2, in, the, with, bat"
25742,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.113636364,"the, is, to, of, human"
25743,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.113636364,"a, of, it, is, sars-cov-2"
25744,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.113636364,"is, that, sars-cov-2, a, laboratory"
25745,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.113636364,"several, have, the, genetic, of"
25746,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.113636364,"the, not, that, any, is"
25747,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.113636364,"is, to, likely, the, bat"
25748,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.113636364,"the, of, that, is, for"
25749,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.113636364,"the, that, sars-cov-2, through, a"
25750,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.113636364,"genomic, that, the, through, of"
25751,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.113636364,"that, to, sars-cov-2, in, pangolins"
25752,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.113636364,"that, the, of, sars-cov-2, this"
25753,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.113636364,"to, the, of, rbd, virus"
25754,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.113636364,"the, sars-cov-2, and, or, of"
25755,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.113636364,"is, the, related, sars-cov-2, in"
25756,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.113636364,"coronavirus, from, been, to, have"
25757,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.113636364,"in, animals, and, to, through"
25758,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.113636364,"from, to, is, contact, and"
25759,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.113636364,"not, a, that, the, was"
25760,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.",0.113636364,"a, of, the, possible, with"
25761,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.113636364,"the, that, a, bat, coronavirus"
25762,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.113636364,"a, coronavirus, in, the, that"
25763,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.113636364,"sars-cov, and, to, in, genetic"
25764,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.113636364,"the, of, and, in, identity"
25765,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.113636364,"that, the, evidence, and, to"
25766,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.113636364,"the, from, that, to, and"
25767,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",The COVID-19 most likely developed from bat origin coronaviruses,0.113636364,"the, most, likely, from, bat"
25768,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.113636364,"the, a, from, intermediate, as"
25769,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.113636364,"the, of, in, that, intermediate"
25770,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.113636364,"that, of, the, genomic, through"
25771,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.113636364,"the, in, that, bats, hosts"
25772,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.113636364,"and, animals, to, through, in"
25773,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.113636364,"are, to, in, and, be"
25774,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",Bats are hosts of many coronaviruses,0.113636364,"bats, are, hosts, of, many"
25775,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.113636364,"by, the, was, in, of"
25776,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.113636364,"the, to, was, of, bat"
25777,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.113636364,"bat, to, is, similar, the"
25778,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.113636364,"the, that, to, bat, and"
25779,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.113636364,"virus, that, with, the, in"
25780,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.113636364,"the, first, in, with, of"
25781,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.113636364,"that, in, has, of, with"
25782,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.113636364,"the, of, first, with, in"
25783,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.113636364,"the, horseshoe, bats, as, of"
25784,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.113636364,"a, of, the, in, china"
25785,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.113636364,"the, natural, reservoir, is, or"
25786,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.113636364,"from, rhinolophus, is, in, the"
25787,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.113636364,"the, of, sites, in, viruses"
25788,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.113636364,"to, the, and, is, be"
25789,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.113636364,"is, and, from, to, contact"
25790,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.113636364,"to, the, and, bats, be"
25791,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.113636364,"the, was, and, caused, in"
25792,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.113636364,"the, in, intermediate, host, was"
25793,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.113636364,"to, on, the, and, or, raccoon, dog, may, be, sars-cov"
25794,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.113636364,"a, and, of, in, the"
25795,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.113636364,"the, two, from, viruses, in"
25796,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.113636364,"the, of, sars-cov-2, and, is"
25797,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.113636364,"the, viruses, sars-cov-2, of, their"
25798,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.113636364,"is, at, the, virus, of"
25799,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.113636364,"is, the, virus, of, sequence"
25800,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.113636364,"from, with, the, of, virus"
25801,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.113636364,"the, of, and, that, is"
25802,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.113636364,"that, the, and, animals, a"
25803,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.113636364,"and, this, the, covid-19, of"
25804,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.113636364,"this, of, and, a, the"
25805,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.113636364,"is, the, to, which, from"
25806,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.113636364,"the, a, to, from, animals"
25807,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.113636364,"the, which, is, to, from"
25808,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.113636364,"to, is, a, from, the"
25809,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.113636364,"the, is, to, after, a"
25810,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.113636364,"the, covid-19, is, a, to"
25811,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.113636364,"is, to, likely, the, which"
25812,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.113636364,"and, that, has, identity, bat"
25813,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.113636364,"a, common, ancestor, with, sars-cov-2"
25814,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.113636364,"that, sars-cov-2, has, with, and"
25815,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.113636364,"in, is, the, bats, and"
25816,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.113636364,"a, sars-cov-2, the, of, virus"
25817,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.113636364,"based, on, analysis, of, was"
25818,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.113636364,"sars-cov-2, to, bat, in, a"
25819,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.113636364,"that, evolved, to, a, it"
25820,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.113636364,"sars-cov-2, to, in, host, bat"
25821,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.113636364,"he, that, of, sars-cov-2, the"
25822,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.113636364,"a, the, that, sars-cov-2, but"
25823,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.113636364,"a, for, as, the, of, and, in, that, to, into"
25824,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.113636364,"in, that, sars-cov-2, has, been"
25825,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.113636364,"the, that, natural, and, a"
25826,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.113636364,"the, most, likely, of, and"
25827,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.113636364,"that, the, of, and, likely"
25828,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.113636364,"our, of, the, sars-cov-2, is"
25829,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.113636364,"the, by, which, a, in"
25830,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.113636364,"sars-cov-2, from, to, are, and"
25831,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.113636364,"that, from, was, to, and"
25832,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.113636364,"viruses, the, evidence, that, be"
25833,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.113636364,"is, the, to, be, pandemic."
25834,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.113636364,"with, the, of, natural, its"
25835,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.113636364,"sequences, from, bat, of, and"
25836,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.113636364,"to, the, of, be, most"
25837,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.113636364,"the, to, that, most, and"
25838,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.113636364,"the, sars-cov-2, bats, pangolins, be"
25839,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.113636364,"the, results, using, that, sars-cov-2"
25840,"All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.113636364,"all, the, that, a, sars-cov-2"
25841,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.113636364,"all, a, that, to, and"
25842,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.113636364,"and, the, from, to, a"
25843,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.113636364,"a, from, the, coronavirus, sars-cov-2"
25844,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.113636364,"that, to, the, bat, and"
25845,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.113636364,"results, that, the, sars-cov-2, using"
25846,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.113636364,"bats, are, the, more, than"
25847,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.113636364,"the, than, indicate, that, virus"
25848,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.113636364,"the, to, bat, that, sars-cov-2"
25849,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.113636364,"to, that, sars-cov-2, the, bats"
25850,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.113636364,"a, the, that, sars-cov-2, for"
25851,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.113636364,"analysis, that, to, bat, the"
25852,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.113636364,"the, analysis, that, and, a"
25853,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.113636364,"to, the, of, a, virus"
25854,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.113636364,"in, wuhan,, the, outbreak, of"
25855,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.113636364,"in, patients, at, a, china"
25856,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.113636364,"at, the, et, of, sars-cov-2"
25857,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.113636364,"a, of, in, the, china"
25858,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.113636364,"was, from, to, a, in"
25859,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.113636364,"a, from, which, sequence, similarity"
25860,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.113636364,"a, of, bat, from, in"
25861,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.113636364,"is, sars-cov-2, a, in, their"
25862,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.113636364,"the, for, viruses, of, and"
25863,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.113636364,"in, genome, similar, to, of"
25864,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.113636364,"that, sars-cov-2, could, be, possible"
25865,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.113636364,"of, the, that, are, for"
25866,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.113636364,"the, that, sars-cov-2, and, a"
25867,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.113636364,"sars-cov-2, the, that, is, of"
25868,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.113636364,"the, that, of, sars-cov-2, is"
25869,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.113636364,"that, the, sarbecovirus, of, sars-cov-2"
25870,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.113636364,"are, in, and, be, to"
25871,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.113636364,"the, evidence, that, viruses, be"
25872,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.113636364,"sars-cov-2, at, the, only, with"
25873,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.113636364,"the, that, sars-cov-2, is, same"
25874,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.113636364,"the, bat, are, cluster, bats, with, that, this, for, is"
25875,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.113636364,"more, of, the, and, that"
25876,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.113636364,"and, that, likely, bats, of"
25877,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.113636364,"the, of, from, that, this"
25878,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.113636364,"and, that, of, the, likely"
25879,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.113636364,"in, the, cov, originated, and"
25880,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.113636364,"the, have, in, or, to"
25881,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.113636364,"is, the, to, sars-cov-2, or"
25882,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.113636364,"the, to, sars-cov-2, bat, in"
25883,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.113636364,"to, which, have, with, sars-cov-2"
25884,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.113636364,"with, the, sars-cov-2, in, bat"
25885,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.113636364,"the, to, bat, is, likely"
25886,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.113636364,"the, to, which, is, likely"
25887,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.113636364,"sars-cov-2, bat, to, in, host"
25888,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.113636364,"and, in, to, that, the, of, sars-, is, are, sars-cov-2"
25889,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.113636364,"that, the, in, bats, hosts"
25890,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.113636364,"that, sars-cov-2, is, bat, the"
25891,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.113636364,"that, sars-cov-2, the, and, similarity"
25892,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.113636364,"of, more, than, that, bats"
25893,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.113636364,"that, of, are, the, sars-cov-2"
25894,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.113636364,"the, of, and, sars-cov-2, or"
25895,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.113636364,"this, sars-cov-2, the, origin, of"
25896,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.113636364,"the, origin, sars-cov-2, and, ratg13"
25897,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.113636364,"that, sars-cov-2, of, the, sarbecovirus"
25898,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.113636364,"that, the, probable, of, sars-cov-2"
25899,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.113636364,"and, origin, of, the, in"
25900,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.113636364,"studies, the, genome, bat, and"
25901,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.113636364,"sequences, of, and, from, bat"
25902,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.113636364,"that, to, sars-cov-2, found, and"
25903,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.113636364,"that, sars-cov-2, are, the, genome"
25904,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.113636364,"to, of, a, with, sars-cov-2"
25905,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.113636364,"of, the, in, between, and"
25906,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.113636364,"in, of, for, sars-cov-2, that"
25907,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.113636364,"and, cov, the, originated, in"
25908,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.113636364,"sars-cov-2, 99%, similarity, with, cov"
25909,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.113636364,"sars-cov-2, to, are, and, in"
25910,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.113636364,"virus, the, and, that, might"
25911,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.113636364,"the, this, that, in, of"
25912,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.113636364,"this, that, the, virus, of"
25913,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.113636364,"at, of, sars-cov-2, and, to"
25914,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.113636364,"the, of, sars-cov-2, to, virus"
25915,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.113636364,"at, and, the, that, to"
25916,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.113636364,"the, and, with, to, of"
25917,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.113636364,"this, of, the, in, that"
25918,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.113636364,"of, the, showed, was, identity"
25919,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.113636364,"the, of, from, identity, sars-cov-2"
25920,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.113636364,"is, of, at, the, in"
25921,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.113636364,"sars-cov-2, pangolin, to, the, of"
25922,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.113636364,"a, to, the, of, from"
25923,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.113636364,"the, of, rbd, to, virus"
25924,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.113636364,"of, a, the, virus, to"
25925,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.113636364,"that, the, of, probable, sars-cov-2"
25926,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.113636364,"the, virus, a, that, has"
25927,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.113636364,"the, virus, been, animal, in"
25928,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.113636364,"that, the, virus, has, of"
25929,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.113636364,"the, of, is, that, for"
25930,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.113636364,"research, that, a, in, sars-cov-2"
25931,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.113636364,"sars-cov-2, a, in, animal, or"
25932,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.113636364,"sars-cov-2, but, that, the, a"
25933,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.113636364,"that, the, for, sars-cov-2, a"
25934,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.113636364,"the, of, is, to, it"
25935,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.113636364,"the, with, of, and, to"
25936,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.113636364,"identified, sars-cov-2, from, in, of"
25937,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.113636364,"bat, a, from, in, china, identified, recent, of, small, including"
25938,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.113636364,"of, a, from, bat, in"
25939,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.113636364,"for, that, in, of, sars-cov-2"
25940,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.113636364,"was, that, the, sars-cov-2, to"
25941,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.113636364,"the, sars-cov-2, of, to, that"
25942,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.113636364,"in, the, and, to, that, sars-cov-2, is, of, are, sars-"
25943,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.113636364,"is, to, bat, be, the"
25944,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.113636364,"is, that, and, of, to"
25945,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.113636364,"the, of, to, sars-cov-2., that"
25946,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.113636364,"the, of, to, high, and"
25947,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.113636364,"the, of, to, sars-cov-2, pangolin"
25948,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.113402062,"that, the, was, an, animal, humans, studies, of, suggesting, have, to"
25949,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.113402062,"in, the, animals, live, from, that, market, to, indicated, a, and"
25950,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.113402062,"studies, the, of, have, suggesting, that, an, animal, was, to, humans"
25951,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.113402062,"indicated, that, the, from, a, market, live, animals, in, to, and"
25952,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.113402062,"live, at, a, known, and, this, in, the, that, to, sars"
25953,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.113402062,"are, viruses, to, based, on, the, in, and, that, bats, for"
25954,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.113402062,"the, to, a, live, that, this, and, sars, in, known, at"
25955,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.113402062,"the, are, to, in, for, based, viruses, on, that, bats, and"
25956,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.113333333,"in, may, the, animals, live, animal, markets, of, found, that, positive, for, to, were, coronavirus, related, and"
25957,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.113333333,"and, of, the, to, markets, live, animals, related, animal, in, were, found, that, positive, for, coronavirus, may"
25958,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.113207547,"in, from, of, bats, and, the"
25959,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.113207547,"a, that, the, infect, and, in"
25960,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.113207547,"the, most, have, reservoirs, of, and"
25961,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.113207547,"and, middle, most, the, of, animal"
25962,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.113207547,"that, of, and, coronavirus, more, bats"
25963,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.113207547,"bats, to, which, sars-cov, of, and"
25964,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.113207547,"bats, are, also, the, of, in"
25965,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.113207547,"the, in, of, to, sars-cov-2, was"
25966,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.113207547,"of, the, in, sars-cov-2, a, with"
25967,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.113207547,"of, multiple, that, a, sars-cov-2, have"
25968,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.113207547,"genetic, the, that, it, to, from"
25969,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.113207547,"the, that, to, of, it, been"
25970,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.113207547,"the, sequences, of, coronaviruses, from, sars-cov-2"
25971,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.113207547,"of, the, sars-cov-2, is, to, coronaviruses"
25972,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.113207547,"genetic, that, a, the, virus, is"
25973,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.113207547,"that, a, naturally, sars-cov-2, and, is"
25974,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.113207547,"the, that, with, natural, sars-cov-2, as"
25975,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.113207547,"that, the, of, bat, a, to"
25976,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.113207547,"has, been, as, of, bat, and"
25977,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.113207547,"sars-cov-2, in, of, and, the, with"
25978,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.113207547,"and, sars-cov-2, to, the, in, with"
25979,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.113207547,"of, the, sars-cov-2, have, origin, and"
25980,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.113207547,"be, zoonosis, the, that, sars-cov-2, animal"
25981,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.113207547,"that, the, of, in, as, a"
25982,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.113207547,"the, used, has, a, that, in"
25983,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.113207547,"the, have, reservoirs, of, and, most"
25984,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.113207547,"the, of, bats, as, host, and"
25985,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.113207547,"the, bats, are, also, in, of"
25986,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.113207547,"virus, that, is, an, to, a"
25987,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.113207547,"the, sequence, that, was, to, and"
25988,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.113207547,"the, is, that, human, and, in"
25989,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.113207547,"the, is, a, sequence, that, in"
25990,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.113207547,"in, to, the, of, origin, is"
25991,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.113207547,"is, to, origin, the, that, this"
25992,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.113207547,"to, the, coronavirus, of, and, a"
25993,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.113207547,"sequence, with, the, of, sars-cov-2, sars-cov"
25994,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.113207547,"is, which, the, ratg13,, in, from"
25995,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.113207547,"in, shows, that, the, is, of"
25996,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.113207547,"that, the, of, sars-cov-2, and, sars-cov"
25997,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.113207547,"the, for, humans, from, animals, at"
25998,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.113207547,"the, at, was, that, in, and"
25999,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.113207547,"that, to, the, and, for, was"
26000,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.113207547,"and, can, are, to, bats, be"
26001,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.113207547,"has, sars-cov-2, the, of, from, in"
26002,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.113207547,"in, of, sars-cov-2, found, to, be"
26003,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.113207547,"studies, sars-cov-2, could, have, and, are"
26004,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.113207547,"as, a, bat, and, similarity, to"
26005,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.113207547,"similarity, to, bat, likely, as, reservoir"
26006,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.113207547,"sars-cov-2, a, of, that, the, as"
26007,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.113207547,"sars-cov-2, could, have, are, studies, and"
26008,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.113207547,"of, the, coronavirus, bat, that, not"
26009,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.113207547,"a, of, sars-cov-2, the, viruses, to"
26010,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.113207547,"the, from, animals, humans, at, for"
26011,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.113207547,"the, market, from, of, sars-cov-2, animals"
26012,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.113207547,"from, humans, the, of, sars-cov-2, animals"
26013,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.113207547,"the, of, from, most, intermediate, for"
26014,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.113207547,"that, the, of, sars-cov-2, and, to"
26015,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.113207547,"the, and, are, to, that, through"
26016,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.113207547,"humans, and, with, the, of, sars-cov-2"
26017,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.113207547,"that, the, market, in, humans, and"
26018,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.113207547,"the, hypothesis, in, and, that, of"
26019,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.113207547,"that, the, in, and, humans, of"
26020,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.113207547,"a, the, of, and, subsequent, is"
26021,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.113207547,"in, a, of, and, the, with"
26022,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.113207547,"the, market, from, a, presence, of"
26023,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.113207547,"a, of, the, at, by, virus"
26024,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.113207547,"the, animal, of, middle, and, most"
26025,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.113207547,"in, the, was, that, at, and"
26026,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.113207547,"in, the, market, animal, and, sars-cov-2"
26027,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.113207547,"that, was, sars-cov-2, sars-cov-1, and, in"
26028,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.113207547,"on, and, were, to, of, in"
26029,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.113207547,"the, of, sars-cov-2, from, animals, market"
26030,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.113207547,"presence, of, a, the, market, from"
26031,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.113207547,"the, sars-cov-2, animal, market, in, and"
26032,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.113207547,"and, the, from, a, market, in"
26033,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.113207547,"of, the, those, in, from, a"
26034,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.113207547,"a, of, from, in, including, sars-cov-2"
26035,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.113207547,"that, a, of, sars-cov-2, have, multiple"
26036,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.113207547,"the, of, sars-cov-2, humans, from, animals"
26037,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.113207547,"have, a, that, different, of, to"
26038,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.113207547,"the, from, that, to, sars-, animals"
26039,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.113207547,"a, of, samples, from, in, sars-cov-2"
26040,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.113207547,"sars-cov-2, was, that, in, sars-cov-1, and"
26041,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.113207547,"are, and, was, from, to, in"
26042,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.113207547,"that, it, is, to, and, was"
26043,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.113207547,"the, sars-cov-2, with, at, be, by"
26044,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.113207547,"the, genetic, that, to, it, from"
26045,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.113207547,"to, the, genome, in, evidence, that"
26046,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.113207547,"sars-cov-2, and, is, a, that, naturally"
26047,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.113207547,"is, a, and, subsequent, of, the"
26048,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.113207547,"a, of, the, sars-cov-2, that, and"
26049,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.113207547,"to, a, as, similarity, and, bat"
26050,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.113207547,"different, of, that, a, have, to"
26051,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.113207547,"that, a, was, the, and, to"
26052,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.113207547,"a, of, in, bats, the, with"
26053,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.113207547,"with, the, of, were, a, and"
26054,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.113207547,"the, who, worked, market, to, of"
26055,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.113207547,"the, with, wuhan, in, market, of"
26056,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.113207547,"the, that, as, intermediate, was, to"
26057,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.113207547,"the, genome, that, and, from, a"
26058,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.113207547,"to, with, the, of, and, from"
26059,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.113207547,"the, of, with, and, sars-cov-2, humans"
26060,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.113207547,"the, of, to, with, from, and"
26061,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.113207547,"the, of, sars-cov-2, spike, protein, to"
26062,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.113207547,"sars-cov-2, a, of, and, that, the"
26063,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.113207547,"to, and, have, the, which, is"
26064,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.113207547,"humans, is, that, the, and, sars-cov-2"
26065,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.113207547,"in, the, market, from, and, a"
26066,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.113207547,"are, was, to, from, and, in"
26067,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.113207547,"to, and, have, a, at, the"
26068,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.113207547,"in, the, to, at, that, virus"
26069,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.113207547,"the, animals, in, transmitted, to, and"
26070,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.113207547,"the, of, virus, to, genetic, is"
26071,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.113207547,"has, the, of, virus, and, to"
26072,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.113207547,"in, humans, the, that, animals, to"
26073,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.113207547,"to, that, the, and, more, origin"
26074,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.113207547,"to, the, bats, of, and, that"
26075,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.113207547,"the, natural, reservoir, is, and, to"
26076,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.113207547,"by, a, of, the, cases, were, december, and, with, huanan, seafood, market,"
26077,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.113207547,"of, in, the, market, with, wuhan"
26078,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.113207547,"the, of, in, market, that, was"
26079,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.113207547,"with, the, of, a, or, that, were, in, where, live, infected, market"
26080,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.113207547,"that, not, the, bat, coronavirus, of"
26081,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.113207547,"of, the, with, bat, sars-like, coronavirus"
26082,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.113207547,"the, of, that, a, with, bat"
26083,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.113207547,"of, to, coronavirus, sars-cov-2, over, the"
26084,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.113207547,"is, the, same, sars-cov-2, that, for"
26085,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.113207547,"sars-cov, and, to, bats, of, which"
26086,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.113207547,"the, of, with, sars-cov, and, to"
26087,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.113207547,"that, bat, similarity, of, with, sars-cov-2"
26088,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.113207547,"of, the, sars-cov-2, have, is, and"
26089,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.113207547,"in, the, those, from, a, of"
26090,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.113207547,"pangolin, in, the, spike, protein, of"
26091,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.113207547,"a, is, virus, that, to, an"
26092,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.113207547,"from, to, humans, is, a, the"
26093,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.113207547,"a, from, the, virus, is, to"
26094,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.113207547,"the, also, in, to, coronaviruses, of"
26095,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.113207547,"is, sars-cov-2, and, to, between, that"
26096,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.113207547,"to, the, coronavirus, of, and, that"
26097,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.113207547,"of, the, coronavirus, with, sars-like, bat"
26098,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.113207547,"coronaviruses, and, belonging, to, the, three"
26099,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.113207547,"coronaviruses, belonging, to, the, three, and"
26100,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.113207547,"of, the, coronavirus, to, beta, coronaviruses"
26101,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.113207547,"and, to, bats, belonging, the, of"
26102,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.113207547,"the, sars-cov-2, to, of, is, coronaviruses"
26103,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.113207547,"coronaviruses, to, the, beta, coronavirus, of"
26104,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.113207547,"the, to, that, sequence, and, was"
26105,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.113207547,"the, to, that, related, bat, and"
26106,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.113207547,"the, of, to, bat, that, as"
26107,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.113207547,"the, sequence, of, more, to, and"
26108,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.113207547,"the, of, to, that, was, from"
26109,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.113207547,"the, a, genome, that, from, and"
26110,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.113207547,"the, is, that, and, genomic, at"
26111,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.113207547,"the, and, market, that, humans, in"
26112,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.113207547,"the, a, to, that, from, and"
26113,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.113207547,"in, animals, to, the, and, transmitted"
26114,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.113207547,"the, sars-cov-2, has, from, in, of"
26115,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.113207547,"the, of, (rhinolophus, in, and, china"
26116,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.113207547,"the, from, sars-cov-2, a, bat, and"
26117,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.113207547,"the, most, for, of, from, intermediate"
26118,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.113207547,"a, from, the, identified, coronavirus, sequence"
26119,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.113207547,"analysis, of, that, most, the, for"
26120,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.113207547,"that, a, the, of, sars-cov-2, and"
26121,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.113207547,"the, of, most, likely, to, hosts"
26122,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.113207547,"the, of, sars-cov-2, that, sars-cov, and"
26123,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.113207547,"to, that, was, the, as, intermediate"
26124,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.113207547,"this, to, that, the, of, evidence"
26125,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.113207547,"sequence, identified, the, a, coronavirus, from"
26126,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.113207547,"the, of, that, been, to, it"
26127,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.113207547,"and, belonging, to, the, bats, of"
26128,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.113207547,"the, of, and, hypothesis, that, in"
26129,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.113207547,"of, from, a, malayan, sars-cov-2, the"
26130,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.113207547,"found, that, the, of, pangolin, to"
26131,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.113207547,"the, of, and, bat, a, in"
26132,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.113207547,"sars-cov-2, in, of, and, the, for"
26133,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.113207547,"and, for, sars-cov-2, to, the, in"
26134,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.113207547,"bats, the, as, of, and, host"
26135,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.113207547,"the, of, were, with, a, and"
26136,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.113207547,"a, natural, its, with, the, for"
26137,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.113207547,"genome, from, the, of, and, covs"
26138,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.113207547,"that, may, have, been, of, pangolin, with, to, and, the, for, sars-cov-2"
26139,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.113207547,"the, of, bat, as, a, to"
26140,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.113207547,"that, the, of, covid-19, viruses, to"
26141,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.113207547,"to, indicate, sars-cov-2, in, the, that"
26142,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.113207547,"in, than, months, the, of, that, for, virus, to, a, is, and"
26143,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.113207547,"that, the, sars-cov-2, and, is, than"
26144,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.113207547,"is, the, to, in, of, than"
26145,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.113207547,"the, of, sars-cov-2, over, to, coronavirus"
26146,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.113207547,"a, from, to, humans, the, is"
26147,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.113207547,"the, of, sars-cov-2, a, from, malayan"
26148,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.113207547,"is, from, 2, in, the, of"
26149,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.113207547,"the, that, sars-, cov-2, is, from"
26150,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.113207547,"sars-cov-2, the, of, coronaviruses, sequences, from"
26151,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.113207547,"with, bat, that, of, sars-cov-2, similarity"
26152,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.113207547,"found, in, to, of, sars-cov-2, ratg13"
26153,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.113207547,"of, and, the, from, in, bats"
26154,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.113207547,"in, the, of, to, sars-cov-2, and"
26155,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.113207547,"at, the, amino, acid, rbd, ratg13"
26156,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.113207547,"with, which, sars-cov-2, at, the, level"
26157,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.113207547,"of, sars-cov-2, ratg13, which, region, the"
26158,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.113207547,"the, be, with, sars-cov-2, at, by"
26159,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.113207547,"ratg13, at, the, rbd, amino, acid"
26160,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.113207547,"the, in, can, a, single, to"
26161,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.113207547,"amino, the, in, a, to, can"
26162,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.113207547,"the, of, sars-cov-2, to, be, natural"
26163,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.113207547,"the, that, sars-cov-2, as, a, of"
26164,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.113207547,"of, sars-cov-2, also, ace2, the, in"
26165,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.113207547,"with, the, and, sars-cov-2, to, in"
26166,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.113207547,"sars-cov-2, to, the, for, in, and"
26167,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.113207547,"in, be, that, the, between, and"
26168,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.113207547,"through, the, that, are, to, and"
26169,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.113207547,"a, and, that, the, in, infect"
26170,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.113207547,"a, the, in, was, to, sars-cov-2"
26171,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.113207547,"and, a, sars-cov-2, in, the, to"
26172,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.113207547,"the, a, to, of, and, laboratory"
26173,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.113207547,"was, that, the, in, market, of"
26174,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.113207547,"sars-cov-2, in, of, that, the, for"
26175,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.113207547,"a, in, the, of, with, bats"
26176,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.113207547,"the, indicate, that, in, to, sars-cov-2"
26177,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.113207547,"coronaviruses, the, including, for, of, natural"
26178,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.113207547,"that, sars-cov-2, genome, a, the, of"
26179,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.113207547,"and, the, of, (rhinolophus, in, china"
26180,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.113207547,"the, of, sars-cov-2, to, most, likely"
26181,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.113207547,"of, the, bat, species, as, intermediate"
26182,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.113207547,"of, to, and, the, intermediate, sars-cov-2"
26183,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.113207547,"the, that, to, bat, and, related"
26184,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.113207547,"that, the, bat, in, closely, to"
26185,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.113207547,"the, that, are, and, in, all"
26186,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.113207547,"the, and, to, of, in, bat"
26187,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.113207547,"the, species, of, to, bat, and"
26188,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.113207547,"in, the, of, that, as, a"
26189,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.113207547,"that, the, covid-19, to, of, bat"
26190,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.113207547,"as, to, the, of, a, bat"
26191,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.113207547,"that, the, of, viruses, to, covid-19"
26192,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.113207547,"to, a, single, in, the, can"
26193,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.113207547,"the, to, that, closely, bat, in"
26194,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.113207547,"at, the, level, which, with, sars-cov-2"
26195,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.113207547,"in, the, two, at, was, similar, to, by, a, closely, related, and"
26196,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.113207547,"the, in, similar, to, sars-cov-2, was"
26197,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.113207547,"of, from, is, in, the, 2"
26198,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.113207547,"the, and, have, is, which, to"
26199,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.113207547,"have, the, and, to, at, a"
26200,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.113207547,"to, a, furin, cleavage, site, and"
26201,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.113207547,"to, and, a, furin, cleavage, site"
26202,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.113207547,"to, is, of, the, virus, genetic"
26203,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.113207547,"the, in, and, sars-cov-2, a, with"
26204,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.113207547,"the, in, are, more, sars-cov-2, than"
26205,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.113207547,"the, sars-cov-2, and, bat, than, share"
26206,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.113207547,"the, and, that, sars-cov-2, is, humans"
26207,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.113207547,"a, market,, the, huanan, seafood, with, december, and, of, cases, were, by"
26208,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.113207547,"of, to, the, market, who, worked"
26209,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.113207547,"on, from, wuhan, the, of, and"
26210,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.113207547,"in, the, of, virus, for, than, is, to, that, and, a, months"
26211,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.113207547,"was, in, by, a, two, closely, related, and, similar, to, at, the"
26212,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.113207547,"the, that, of, first, known, human, with, and, in, sample, at, also"
26213,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.113207547,"that, the, infected, with, in, market, where, live, were, or, a, of"
26214,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.113207547,"were, of, in, and, to, on"
26215,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.113207547,"is, the, that, in, human, and"
26216,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.113207547,"that, the, genomic, and, is, at"
26217,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.113207547,"the, that, are, all, in, and"
26218,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.113207547,"the, also, first, that, with, and, human, in, of, sample, known, at"
26219,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.113207547,"that, genomic, with, the, in, collected"
26220,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.113207547,"the, that, with, at, of, and"
26221,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.113207547,"with, the, a, natural, for, its"
26222,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.113207547,"virus, is, with, sars-cov-2, the, on"
26223,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.113207547,"the, that, with, genomic, in, collected"
26224,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.113207547,"to, the, spike, protein, of, sars-cov-2"
26225,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.113207547,"the, most, likely, to, of, sars-cov-2"
26226,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.113207547,"that, the, of, sars-cov-2, this, likely"
26227,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.113207547,"that, sars-, cov-2, from, is, the"
26228,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.113207547,"from, that, the, virus, is, previously"
26229,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.113207547,"reservoir, to, as, likely, similarity, bat"
26230,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.113207547,"the, of, that, to, bat, as"
26231,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.113207547,"that, the, of, bat, as, to"
26232,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.113207547,"the, not, to, it, that, in"
26233,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.113207547,"a, in, the, that, from, human"
26234,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.113207547,"of, the, spike, protein, in, pangolin"
26235,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.113207547,"the, natural, for, of, coronaviruses, including"
26236,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.113207547,"of, that, is, to, the, for"
26237,"Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.113207547,"based, the, of, that, in, is"
26238,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.113207547,"is, to, have, very, in, or"
26239,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.113207547,"the, in, that, of, based, is"
26240,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.113207547,"the, sequence, of, to, and, more"
26241,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.113207547,"from, sars-, the, that, animals, to"
26242,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.113207547,"the, species, as, of, intermediate, bat"
26243,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.113207547,"that, the, covid-19, intermediate, hosts, of"
26244,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.113207547,"the, of, and, that, humans, in"
26245,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.113207547,"of, that, the, covid-19, intermediate, hosts"
26246,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.113207547,"the, have, been, in, of, that"
26247,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.113207547,"the, was, that, to, and, for"
26248,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.113207547,"that, it, was, to, and, is"
26249,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.113207547,"analysis, the, of, that, most, for"
26250,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.113207547,"to, the, that, for, is, of"
26251,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.113207547,"the, that, of, is, it, for"
26252,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.113207547,"to, that, the, of, and, for"
26253,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.113207547,"that, the, and, bats, of, to"
26254,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.113207547,"of, the, have, been, in, that"
26255,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.113207547,"to, in, the, that, it, not"
26256,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.113207547,"the, species, from, by, bat, rhinolophus"
26257,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.113207547,"are, bats, and, can, be, to"
26258,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.113207547,"the, origin, of, have, and, sars-cov-2"
26259,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.113207547,"have, the, sars-cov-2, and, of, is"
26260,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.113207547,"sars-cov-2, is, virus, with, on, the"
26261,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.113207547,"on, from, in, the, of, virus"
26262,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.113207547,"and, bat, has, been, as, of"
26263,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.113207547,"to, the, most, likely, hosts, of"
26264,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.113207547,"the, by, bat, from, rhinolophus, species"
26265,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.113207547,"a, that, the, virus, is, of"
26266,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.113207547,"of, a, virus, at, the, by"
26267,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.113207547,"is, that, a, the, virus, genetic"
26268,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.113207547,"is, that, a, the, of, virus"
26269,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.113207547,"that, sars-cov-2, with, as, the, natural"
26270,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.113207547,"of, that, it, is, the, for"
26271,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.113207547,"the, of, to, in, is, origin"
26272,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.113207547,"is, the, ratg13,, which, in, from"
26273,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.113207547,"is, in, the, bat, pangolin, which"
26274,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.113207547,"found, of, ratg13, to, sars-cov-2, in"
26275,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.113207547,"the, that, to, is, this, origin"
26276,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.113207547,"the, of, to, be, sars-cov-2, natural"
26277,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.113207547,"sars-cov-2, also, ace2, in, of, the"
26278,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.113207547,"in, the, that, has, a, used"
26279,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.113207547,"a, is, the, that, in, sequence"
26280,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.113207547,"the, of, that, evidence, to, this"
26281,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.113207547,"to, the, and, evidence, that, be"
26282,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.113207547,"a, sars-cov-2, and, the, from, bat"
26283,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.113207547,"bat, and, the, all, sars-cov-2, cluster"
26284,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.113207547,"a, cluster, sars-cov-2, to, coronavirus, that"
26285,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.113207547,"the, shows, that, is, in, of"
26286,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.113207547,"the, that, is, from, previously, virus"
26287,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.113207547,"and, a, of, which, the, to"
26288,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.113207547,"a, viruses, to, the, of, sars-cov-2"
26289,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.113207547,"ratg13, the, of, which, region, sars-cov-2"
26290,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.113207547,"a, the, to, and, in, sars-cov-2"
26291,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.113207547,"ratg13, is, the, to, in, of"
26292,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.113207547,"found, of, pangolin, have, to, sars-cov-2."
26293,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.113207547,"sars-cov-2, and, of, the, have, been, to, pangolin, with, that, for, may"
26294,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.113207547,"the, to, of, sars-cov-2, intermediate, and"
26295,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.113207547,"a, of, the, in, with, sars-cov-2"
26296,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.113207547,"that, the, with, in, a, of"
26297,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.113207547,"a, in, with, sars-cov-2, the, and"
26298,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.113207547,"evidence, the, that, in, genome, to"
26299,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.113207547,"to, be, that, bats, and, the"
26300,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.113207547,"to, that, the, and, evidence, be"
26301,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.113207547,"the, results, that, are, to, genome"
26302,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.113207547,"that, the, sars-cov-2, same, for, is"
26303,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.113207547,"of, more, and, that, bats, coronavirus"
26304,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.113207547,"the, and, that, sars-cov-2, is, to"
26305,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.113207547,"is, between, and, that, sars-cov-2, to"
26306,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.113207547,"is, very, to, in, have, or"
26307,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.113207547,"is, which, the, bat, in, pangolin"
26308,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.113207547,"are, in, more, sars-cov-2, than, the"
26309,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.113207547,"the, than, is, that, sars-cov-2, and"
26310,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.113207547,"share, sars-cov-2, than, the, bat, and"
26311,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.113207547,"the, all, sars-cov-2, cluster, bat, and"
26312,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.113207547,"the, origin, more, to, that, and"
26313,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.113207547,"of, that, to, the, and, for"
26314,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.113207547,"the, virus, in, and, from, china"
26315,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.113207547,"the, of, genome, covs, from, and"
26316,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.113207547,"of, and, bat, between, in, the"
26317,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.113207547,"the, from, and, of, wuhan, on"
26318,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.113207547,"virus, from, in, the, of, on"
26319,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.113207547,"a, of, the, with, bat, that"
26320,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.113207547,"are, to, the, genome, results, that"
26321,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.113207547,"of, to, is, with, sars-cov-2, the"
26322,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.113207547,"the, that, of, with, and, at"
26323,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.113207547,"that, and, be, the, between, in"
26324,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.113207547,"the, of, that, from, was, to"
26325,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.113207547,"that, the, virus, in, to, at"
26326,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.113207547,"the, zoonosis, be, that, animal, sars-cov-2"
26327,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.113207547,"from, a, in, the, that, human"
26328,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.113207547,"to, the, and, natural, reservoir, is"
26329,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.113207547,"in, including, from, a, of, sars-cov-2"
26330,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.113207547,"samples, from, in, of, a, sars-cov-2"
26331,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.113207547,"sars-cov-2, to, in, of, be, found"
26332,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.113207547,"that, sars-cov-2, to, a, cluster, coronavirus"
26333,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.113207547,"to, a, amino, in, the, can"
26334,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.113207547,"in, the, of, than, is, to"
26335,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.113207547,"of, ratg13, in, is, the, to"
26336,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.113207547,"the, of, in, also, to, coronaviruses"
26337,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.113207547,"found, the, of, that, to, pangolin"
26338,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.113095238,"to, the, sars, were, as, for, infections, and, not, a, reservoir, in, of, study, sampled, from, that, an, found"
26339,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.113095238,"as, a, of, the, and, were, in, an, to, sars, for, study, found, that, from, sampled, infections, not, reservoir"
26340,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.113043478,"of, a, to, markets, and, the, market, were, only, in, approximately, known, direct"
26341,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.113043478,"in, the, known, markets, of, approximately, only, market, to, were, a, and, direct"
26342,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.112903226,"that, infected, with, animals, were, or, of"
26343,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.112903226,"the, of, virus, to, with, human, and"
26344,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.112903226,"sars-cov-2, have, been, from, to, genetic, coronaviruses"
26345,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.112903226,"of, the, sars-cov-2, have, in, is, and"
26346,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.112903226,"are, of, many, and, to, that, human"
26347,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.112903226,"in, of, and, residues, that, as, intermediate"
26348,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.112903226,"bats, a, as, the, of, in, that"
26349,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.112903226,"viruses, the, have, been, bats, of, and"
26350,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.112903226,"in, the, of, that, as, a, bats"
26351,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.112903226,"the, virus, into, an, in, to, and"
26352,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.112903226,"the, that, with, of, virus, and, to"
26353,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.112903226,"the, that, from, animals, to, and, for"
26354,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.112903226,"for, the, sars-cov, palm, as, natural, and"
26355,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.112903226,"to, that, the, and, as, hosts, for"
26356,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.112903226,"and, to, that, the, of, is, sars-cov-2"
26357,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.112903226,"animals, from, that, to, for, and, the"
26358,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.112903226,"sars-cov-2, genetic, have, been, to, coronaviruses, from"
26359,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.112903226,"the, viruses, are, sars-cov-2, by, of, their"
26360,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.112903226,"the, sars-cov-2, their, and, this, origin, of"
26361,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.112903226,"in, the, of, that, sars-cov-2, with, and"
26362,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.112903226,"as, the, of, and, published, in, to"
26363,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.112903226,"a, sars-cov-2, and, the, of, from, in"
26364,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.112903226,"in, a, of, sars-cov-2, to, that, may"
26365,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.112903226,"analysis, of, the, that, is, a, virus"
26366,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.112903226,"our, of, data, the, that, is, a"
26367,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.112903226,"a, and, high, to, indicates, that, in"
26368,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.112903226,"the, published, in, as, to, of, and"
26369,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.112903226,"such, and, in, their, to, the, of"
26370,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.112903226,"bats, and, a, to, that, humans,, as"
26371,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.112903226,"a, with, and, which, to, the, genome"
26372,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.112903226,"to, sars-cov-2, from, of, the, and, with"
26373,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.112903226,"in, the, and, to, that, have, through"
26374,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.112903226,"was, in, and, which, are, to, the"
26375,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.112903226,"and, of, in, which, is, the, to"
26376,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.112903226,"the, to, animal, in, and, virus, sars-cov"
26377,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.112903226,"of, december, reported, and, the, huanan, in"
26378,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.112903226,"as, natural, for, sars-cov, and, the, palm"
26379,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.112903226,"the, of, human, a, high, and, as"
26380,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.112903226,"of, animals, that, were, infected, with, or"
26381,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.112903226,"that, may, have, a, of, with, the"
26382,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.112903226,"that, the, of, bat, but, viruses, a"
26383,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.112903226,"the, was, to, which, sars-cov, for, and"
26384,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.112903226,"was, the, and, for, to, which, sars-cov"
26385,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.112903226,"sars-cov, cov, and, sars-cov-2, covs, with, similarity"
26386,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.112903226,"isolated, from, a, pangolin, spike, in, the"
26387,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.112903226,"for, the, virus, from, a, humans, to"
26388,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.112903226,"the, virus, and, in, to, an, into"
26389,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.112903226,"the, and, species, that, from, barrier, humans"
26390,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.112903226,"sars-cov-2, of, animal, species, and, that, intermediate"
26391,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.112903226,"ace2, in, of, mice, and, the, with"
26392,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.112903226,"the, of, coronaviruses, with, a, and, or"
26393,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.112903226,"with, the, of, pangolin, to, as, intermediate"
26394,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.112903226,"to, from, a, in, the, and, that"
26395,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.112903226,"in, the, from, and, a, of, sars-cov-2"
26396,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.112903226,"sequence, in, the, of, a, isolated, from"
26397,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.112903226,"a, sequence, the, of, isolated, from, in"
26398,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.112903226,"in, a, of, for, were, coronavirus, that"
26399,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.112903226,"the, that, genomes, to, a, bat, and"
26400,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.112903226,"indicates, that, in, to, a, high, and"
26401,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.112903226,"coronavirus, from, a, with, sars-cov-2, has, the"
26402,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.112903226,"a, the, of, data, our, that, is"
26403,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.112903226,"on, the, of, in, and, that, a"
26404,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.112903226,"from, as, and, the, of, sars-cov-2, a"
26405,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.112903226,"a, the, as, of, high, and, human"
26406,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.112903226,"that, related, to, covs, were, found, bats"
26407,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.112903226,"a, of, and, the, with, as, for"
26408,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.112903226,"the, of, have, to, live, animal, in, markets, and, wild, animals, were, sars-cov, civet"
26409,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.112903226,"to, with, the, of, and, virus, human"
26410,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.112903226,"the, of, with, and, that, sars-cov-2, in"
26411,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.112903226,"of, sequences, to, a, from, found, in"
26412,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.112903226,"and, that, the, of, sars-, is, sars-cov-2"
26413,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.112903226,"of, to, reported, and, the, were, in"
26414,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.112903226,"sars-cov-2, of, the, with, rbd, s, protein"
26415,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.112903226,"it, is, that, the, be, and, sars-cov-2"
26416,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.112903226,"the, rbd, of, is, to, sars-cov-2, that"
26417,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.112903226,"and, that, residues, of, in, intermediate, as"
26418,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.112903226,"and, that, of, sars-cov-2, intermediate, animal, species"
26419,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.112903226,"ace2, mice, and, with, the, in, of"
26420,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.112903226,"with, the, of, as, a, for, and"
26421,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.112903226,"pangolins, in, with, sars-cov-2, the, amino, on"
26422,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.112903226,"through, have, that, the, in, and, to"
26423,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.112903226,"a, amino, acid, sars-cov-2, to, be, the"
26424,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.112903226,"the, species, of, to, humans, by, and"
26425,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.112903226,"a, who, was, that, the, to, of"
26426,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.112903226,"seafood, market, in, the, to, of, were"
26427,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.112903226,"to, from, and, with, the, of, sars-cov-2"
26428,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.112903226,"that, the, from, a, in, to, and"
26429,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.112903226,"that, the, in, bats, and, to, of"
26430,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.112903226,"to, recombination, the, of, from, a, with"
26431,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.112903226,"natural, of, a, related, to, zoonotic, in"
26432,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.112903226,"in, the, role, of, an, to, and"
26433,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.112903226,"a, of, the, bat, viruses, that, but"
26434,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.112903226,"by, genome, at, the, is, related, to"
26435,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.112903226,"the, a, genome, which, to, with, and"
26436,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.112903226,"are, in, to, the, which, and, was"
26437,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.112903226,"of, the, by, sars-cov-2, are, viruses, their"
26438,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.112903226,"to, closely, related, the, of, are, sars-cov-2"
26439,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.112903226,"the, closely, related, is, in, virus, to"
26440,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.112903226,"and, the, it, be, that, sars-cov-2, is"
26441,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.112903226,"a, virus, from, to, humans, for, the"
26442,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.112903226,"that, the, species, barrier, and, humans, from"
26443,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.112903226,"evidence, for, and, that, in, the, of"
26444,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.112903226,"and, to, an, role, in, the, of"
26445,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.112903226,"huanan, in, the, reported, december, and, of"
26446,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.112903226,"in, of, were, reported, to, and, the"
26447,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.112903226,"are, and, a, to, zoonotic, that, in"
26448,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.112903226,"coronaviruses, and, a, the, of, with, or"
26449,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.112903226,"not, a, but, and, the, to, one"
26450,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.112903226,"to, of, in, bats, the, and, that"
26451,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.112903226,"bats, the, have, been, of, and, viruses"
26452,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.112903226,"in, city, china, the, of, these, and"
26453,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.112903226,"the, virus, to, and, sars-cov, in, animal"
26454,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.112903226,"and, of, the, have, to, markets, live, wild, animals, civet, animal, in, were, sars-cov"
26455,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.112903226,"the, sars-cov-2, and, have, of, is, in"
26456,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.112903226,"sars-cov-2, pangolins, on, the, amino, in, with"
26457,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.112903226,"the, to, and, a, but, one, not"
26458,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.112903226,"the, of, to, species, humans, and, by"
26459,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.112903226,"the, spike, in, isolated, from, a, pangolin"
26460,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.112903226,"a, from, the, has, coronavirus, with, sars-cov-2"
26461,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.112903226,"a, of, the, virus, that, analysis, is"
26462,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.112903226,"sars-cov, and, not, for, the, have, been"
26463,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.112903226,"the, of, sars-cov-2, as, a, from, and"
26464,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.112903226,"the, for, sars-cov, and, have, not, been"
26465,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.112903226,"such, the, of, and, their, in, to"
26466,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.112903226,"to, sars-cov-2, in, the, is, of, natural"
26467,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.112903226,"sars-cov-2, and, ratg13, compared, to, that, in"
26468,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.112903226,"the, and, bat, that, a, genomes, to"
26469,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.112903226,"a, using, obtained, from, that, the, to"
26470,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.112903226,"the, and, also, a, to, that, bat"
26471,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.112903226,"bats, were, found, to, covs, related, that"
26472,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.112903226,"who, that, the, of, a, was, to"
26473,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.112903226,"of, the, in, to, were, seafood, market"
26474,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.112903226,"related, to, by, is, at, the, genome"
26475,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.112903226,"the, obtained, from, using, that, to, a"
26476,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.112903226,"of, the, and, to, virus, analysis, many"
26477,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.112903226,"of, from, to, a, found, in, sequences"
26478,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.112903226,"in, to, is, of, the, which, and"
26479,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.112903226,"that, the, with, may, have, a, of"
26480,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.112903226,"the, in, and, on, that, a, of"
26481,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.112903226,"sars-cov-2, of, the, and, viruses, with, in"
26482,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.112903226,"in, to, that, sars-cov-2, and, compared, ratg13"
26483,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.112903226,"the, sars-cov-2, cluster, and, bat, pangolin, of"
26484,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.112903226,"origin, of, the, this, sars-cov-2, and, their"
26485,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.112903226,"the, and, sars-cov-2, of, bat, pangolin, cluster"
26486,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.112903226,"as, hosts, that, to, for, and, the"
26487,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.112903226,"of, for, sars-cov-2, to, origin, that, may"
26488,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.112903226,"the, in, of, and, these, city, china"
26489,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.112903226,"sars-cov-2, of, on, the, and, similar, to"
26490,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.112903226,"for, the, of, and, that, in, evidence"
26491,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.112903226,"and, the, that, for, of, sars-cov-2, in"
26492,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.112903226,"and, for, the, of, that, sars-cov-2, in"
26493,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.112903226,"cov, with, covs, sars-cov-2, and, similarity, sars-cov"
26494,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.112903226,"the, of, virus, and, with, that, to"
26495,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.112903226,"the, of, rbd, to, that, sars-cov-2, is"
26496,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.112903226,"to, from, a, recombination, of, the, with"
26497,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.112903226,"in, of, that, a, sars-cov-2, may, to"
26498,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.112903226,"in, of, a, coronavirus, that, were, for"
26499,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.112903226,"to, that, of, may, for, origin, sars-cov-2"
26500,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.112903226,"and, are, of, that, many, to, human"
26501,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.112903226,"to, a, that, bats, and, humans,, as"
26502,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.112903226,"of, natural, zoonotic, to, a, related, in"
26503,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.112903226,"are, a, zoonotic, and, in, that, to"
26504,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.112903226,"of, the, sars-, that, and, sars-cov-2, is"
26505,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.112903226,"the, are, closely, related, to, sars-cov-2, of"
26506,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.112903226,"be, of, the, to, in, rbd, s"
26507,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.112903226,"the, that, to, a, also, bat, and"
26508,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.112903226,"to, the, of, with, pangolin, as, intermediate"
26509,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.112903226,"s, protein, the, of, rbd, with, sars-cov-2"
26510,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.112903226,"of, analysis, the, virus, to, many, and"
26511,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.112903226,"of, the, in, and, sars-cov-2, with, viruses"
26512,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.112903226,"sars-cov-2, similar, to, and, on, the, of"
26513,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.112903226,"the, to, be, in, rbd, of, s"
26514,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.112676056,"the, of, sars-cov-2,, in, and, virus,, that, a"
26515,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.112676056,"of, the, emergence, and, with, to, virus, infection"
26516,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.112676056,"to, sars-cov-2, a, of, in, the, it, with"
26517,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.112676056,"the, acid, of, sars-cov-2, and, domains,, which, a"
26518,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.112676056,"the, was, that, virus, to, human, and, sequence"
26519,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.112676056,"to, the, and, their, is, be, host, for"
26520,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.112676056,"a, of, be, the, coronavirus, with, that, bats"
26521,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.112676056,"the, of, in, on, it, that, were, is"
26522,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.112676056,"the, of, on, is, likely, in, to, that"
26523,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.112676056,"the, of, were, that, in, this, likely, to"
26524,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.112676056,"the, it, likely, that, zoonotic, of, in, this"
26525,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.112676056,"it, to, this, the, of, that, suggested, in"
26526,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.112676056,"the, and, coronaviruses, that, a, in, are, to"
26527,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.112676056,"a, from, was, at, in, that, the, to"
26528,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.112676056,"in, of, to, the, this, is, from, found"
26529,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.112676056,"from, to, this, the, of, sars-cov-2, been, in"
26530,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.112676056,"of, from, without, an, a, in, sars-cov-2, the"
26531,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.112676056,"the, to, from, in, of, this, is, found"
26532,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.112676056,"on, the, of, that, were, in, it, is"
26533,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.112676056,"in, the, and, that, to, from, through, market"
26534,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.112676056,"that, more, the, to, in, natural, origin, and"
26535,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.112676056,"for, the, is, and, be, their, to, host"
26536,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.112676056,"the, of, sars-cov, and, bat, a, sequence, among"
26537,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.112676056,"a, of, in, the, it, suggested, that, with"
26538,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.112676056,"bats, a, coronavirus, the, of, be, with, that"
26539,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.112676056,"sars-cov, and, novel, the, beta, of, with, as"
26540,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.112676056,"and, recently, to, that, the, of, is, sars-cov-2"
26541,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.112676056,"of, the, covid-19, between, december, and, 2019, with"
26542,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.112676056,"novel, with, beta, the, of, as, and, sars-cov"
26543,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.112676056,"the, a, to, live, in, and, animals, market"
26544,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.112676056,"in, the, a, that, coronaviruses, are, to, and"
26545,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.112676056,"a, the, sars-cov, of, bat, among, and, sequence"
26546,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.112676056,"sars-cov-2, may, in, a, species, and, that, as"
26547,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.112676056,"that, and, may, be, sars-cov-2, to, between, in"
26548,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.112676056,"the, acid, sars-cov-2, and, domains,, which, a, of"
26549,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.112676056,"from, to, was, the, of, sars-cov-2, in, a"
26550,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.112676056,"in, the, to, that, sars-cov-2, of, ratg13, pangolin"
26551,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.112676056,"the, of, in, and, that, this, than, a"
26552,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.112676056,"in, the, without, from, an, a, of, sars-cov-2"
26553,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.112676056,"pangolin, to, sars-cov-2, in, the, that, is, of"
26554,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.112676056,"to, that, sars-, cov-2, the, of, bats, sars-cov-2"
26555,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.112676056,"sars-cov-2, a, and, species, as, that, may, in"
26556,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.112676056,"sars-cov-2, between, and, be, to, that, may, in"
26557,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.112676056,"in, to, that, sars-cov-2, based, on, and, amino"
26558,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.112676056,"the, of, were, in, earliest, human, with, to"
26559,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.112676056,"a, of, the, in, it, to, with, sars-cov-2"
26560,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.112676056,"it, suggested, that, the, with, in, a, of"
26561,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.112676056,"it, that, sars-cov-2, a, the, result, of, from"
26562,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.112676056,"sars-cov-2, result, from, a, of, the, it, that"
26563,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.112676056,"to, sars-cov-2, a, in, the, and, it, with"
26564,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.112676056,"on, the, of, that, to, in, is, likely"
26565,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.112676056,"of, the, covid-19, with, between, december, 2019, and"
26566,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.112676056,"the, of, that, a, virus, in, animal, for"
26567,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.112676056,"the, of, that, were, to, in, this, likely"
26568,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.112676056,"of, the, earliest, human, in, to, were, with"
26569,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.112676056,"virus, the, was, to, and, sequence, that, human"
26570,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.112676056,"the, of, that, in, it, this, likely, zoonotic"
26571,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.112676056,"through, that, the, in, and, to, from, market"
26572,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.112676056,"the, a, market, live, animals, in, to, and"
26573,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.112676056,"a, by, at, that, the, virus, to, of"
26574,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.112676056,"the, also, has, a, to, that, are, of"
26575,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.112676056,"the, of, that, to, in, it, suggested, this"
26576,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.112676056,"the, sars-cov-2, been, to, from, in, of, this"
26577,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.112676056,"the, to, sars-cov-2, was, in, from, of, a"
26578,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.112676056,"that, and, sars-cov-2, to, based, on, amino, in"
26579,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.112676056,"and, ratg13, this, that, the, between, origin, is"
26580,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.112676056,"the, natural, origin, more, to, that, in, and"
26581,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.112676056,"in, the, a, was, that, from, to, at"
26582,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.112676056,"a, of, the, at, by, that, to, virus"
26583,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.112676056,"the, of, in, receptor, binding, and, (2020), a"
26584,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.112676056,"sars-cov-2, of, the, and, with, similar, to, virus"
26585,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.112676056,"a, of, and, that, the, virus,, sars-cov-2,, in"
26586,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.112676056,"in, the, of, than, that, and, this, a"
26587,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.112676056,"and, (2020), a, of, in, receptor, binding, the"
26588,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.112676056,"is, origin, the, that, ratg13, between, and, this"
26589,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.112676056,"in, the, of, that, sars-cov-2, to, ratg13, pangolin"
26590,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.112676056,"that, of, sars-, cov-2, bats, to, sars-cov-2, the"
26591,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.112676056,"a, of, in, that, animal, for, the, virus"
26592,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.112676056,"recently, the, sars-cov-2, and, of, is, to, that"
26593,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.112676056,"a, of, the, has, also, are, that, to"
26594,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.112676056,"to, with, the, emergence, of, and, virus, infection"
26595,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.112676056,"of, virus, with, similar, to, and, the, sars-cov-2"
26596,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.1125,"and, in, found, to, be, the, of, is, sars-cov-2"
26597,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.1125,"bats, are, of, and, a, to, that, in, as"
26598,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.1125,"and, at, the, that, was, for, in, from, a"
26599,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.1125,"from, and, to, was, for, the, that, in, a"
26600,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.1125,"that, are, the, of, and, two, viruses, in, least"
26601,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.1125,"the, of, an, at, that, samples, taken, infected, to"
26602,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.1125,"such, as, and, to, this, the, authors, of, in"
26603,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.1125,"and, to, be, the, of, sars-, coronavirus, bats, natural"
26604,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.1125,"from, intermediate, for, the, of, that, suggested, in, a"
26605,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.1125,"this, that, in, and, the, virus, new, for, of"
26606,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.1125,"to, an, the, of, infected, at, samples, taken, that"
26607,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.1125,"in, the, a, was, that, from, at, and, for"
26608,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.1125,"of, the, that, and, are, least, two, in, viruses"
26609,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.1125,"in, the, a, was, that, from, to, and, for"
26610,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.1125,"authors, such, as, the, of, and, in, this, to"
26611,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.1125,"in, the, of, a, from, suggested, that, intermediate, for"
26612,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.1125,"the, authors, that, of, sars-cov-2, laboratory, it, as, for"
26613,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.1125,"as, it, for, the, authors, of, that, sars-cov-2, laboratory"
26614,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.1125,"the, sars-cov-2, to, by, in, of, natural, origin, and"
26615,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.1125,"by, and, in, to, the, of, sars-cov-2, natural, origin"
26616,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.1125,"and, the, of, new, that, this, in, for, virus"
26617,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.1125,"bats, are, a, as, of, and, in, that, to"
26618,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.1125,"the, sars-cov-2, and, to, be, of, is, found, in"
26619,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.1125,"and, sars-, to, the, coronavirus, bats, be, natural, of"
26620,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.112359551,"the, of, sars-cov-2, to, human, ace2, a, or, that, not"
26621,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.112359551,"that, have, a, of, virus, to, and, the, for, sars-cov-2"
26622,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.112359551,"from, the, in, january, its, 2020, a, was, no, any"
26623,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.112359551,"a, by, was, market, in, that, the, to, of, were"
26624,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.112359551,"a, the, huanan, with, and, market, of, cases, were, to"
26625,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.112359551,"the, of, cases, were, to, with, a, and, huanan, market"
26626,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.112359551,"the, market, wuhan, that, have, in, of, were, with, a"
26627,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.112359551,"an, infected, to, from, animal, in, the, virus, or, and"
26628,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.112359551,"in, the, sars, for, virus, to, were, closely, related, and"
26629,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.112359551,"the, of, and, were, that, collected, a, found, earliest, with"
26630,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.112359551,"cases, and, the, huanan, seafood, market,, that, of, a, by"
26631,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.112359551,"the, virus, for, sars, and, closely, related, to, were, in"
26632,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.112359551,"collected, a, of, the, found, that, were, and, with, earliest"
26633,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.112359551,"the, virus, from, an, animal, in, or, infected, to, and"
26634,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.112359551,"was, from, a, no, the, its, in, any, january, 2020"
26635,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.112359551,"that, the, with, wuhan, in, have, market, were, a, of"
26636,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.112359551,"and, a, of, in, is, an, the, for, to, 2"
26637,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.112359551,"by, a, of, the, that, cases, and, huanan, seafood, market,"
26638,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.112359551,"sars-cov-2, of, to, human, ace2, a, or, that, not, the"
26639,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.112359551,"et, al., may, been, by, of, to, and, are, the"
26640,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.112359551,"that, the, of, market, in, was, to, were, a, by"
26641,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.112359551,"the, is, in, for, of, 2, to, and, a, an"
26642,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.112359551,"sars-cov-2, of, for, to, a, virus, have, that, and, the"
26643,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.112359551,"the, by, of, are, to, and, been, et, al., may"
26644,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.112244898,"and, the, of, bat, to, a, other, in, recombination, which, is"
26645,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.112244898,"of, the, bats, most, coronaviruses,, and, viruses, more, than, any, other"
26646,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.112244898,"a, of, receptor, is, an, the, for, to, human, enzyme, 2"
26647,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.112244898,"in, the, animals, from, that, as, two, market, to, a, evidence"
26648,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.112244898,"made, to, was, not, by, the, of, that, have, in, a"
26649,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.112244898,"the, animals, are, to, in, of, is, was, bats, virus, and"
26650,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.112244898,"the, and, which, to, a, of, is, in, other, bat, recombination"
26651,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.112244898,"evidence, the, that, in, a, as, to, two, from, animals, market"
26652,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.112244898,"the, of, evidence, at, that, is, a, virus, in, animal, for"
26653,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.112244898,"bats, the, most, of, coronaviruses,, and, more, viruses, than, any, other"
26654,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.112244898,"are, in, animals, to, is, of, the, virus, bats, and, was"
26655,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.112244898,"the, of, at, this, that, sars-cov-2, is, a, in, animal, for"
26656,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.112244898,"that, the, of, in, was, to, not, made, have, a, by"
26657,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.112244898,"enzyme, 2, receptor, to, human, the, an, a, of, is, for"
26658,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.112244898,"in, the, animal, of, that, for, at, virus, a, is, evidence"
26659,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.112244898,"the, for, of, a, that, in, this, is, sars-cov-2, animal, at"
26660,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.112149533,"to, the, for, and, a, of, from, horseshoe, (rhinolophus, that, genome, identity"
26661,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.112149533,"in, the, of, for, not, to, see, that, sars-cov-2, been, with, and"
26662,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.112149533,"see, sars-cov-2, and, of, the, been, to, in, not, with, that, for"
26663,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.112149533,"the, is, that, of, first, known, market, and, in, collected, at, also"
26664,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.112149533,"the, for, a, genome, of, to, identity, that, from, and, horseshoe, (rhinolophus"
26665,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.112149533,"in, the, first, known, of, that, at, market, also, collected, is, and"
26666,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.112068966,"in, the, of, that, for, as, also, virus, to, a, coronavirus, is, and"
26667,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.112068966,"of, the, market, animal, were, in, to, it, large, number, infected, that, suggested"
26668,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.112068966,"had, into, to, this, was, not, the, of, that, suggested, have, in, a"
26669,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.112068966,"also, a, for, coronavirus, as, the, of, is, virus, and, in, that, to"
26670,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.112068966,"the, large, number, of, infected, that, were, to, animal, market, in, it, suggested"
26671,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.112068966,"this, suggested, that, had, a, the, was, into, of, in, not, have, to"
26672,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.112,"as, a, of, the, palm, and, it, with, for, study, positive, prevalence, among, reservoir"
26673,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.112,"a, study, for, the, palm, as, reservoir, positive, prevalence, of, among, and, it, with"
26674,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.112,"the, market, is, that, in, for, researchers, of, were, to, by, and, with, a"
26675,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.112,"the, to, in, a, for, of, researchers, with, is, that, were, by, and, market"
26676,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.111111111,"bats, in, of"
26677,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.111111111,"in, of, a, bats"
26678,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.111111111,"bats, a, of, coronaviruses"
26679,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.111111111,"n, in, bats"
26680,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.111111111,"that, the, from, a, in, and"
26681,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.111111111,"that, in, bats, and, pangolins, from"
26682,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.111111111,"that, the, in, bats, and, of"
26683,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.111111111,"that, the, of, and, from, bats"
26684,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.111111111,"to, and, sars-cov, which, bat, human"
26685,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.111111111,"a, which, to, pangolin, and, bat"
26686,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.111111111,"a, to, and, in, sars-cov-2"
26687,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.111111111,"genetic, viral, and, human, a"
26688,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.111111111,"a, pangolin, to, and, are, sars-cov-2"
26689,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.111111111,"in, and, sars-cov-2, a, viruses"
26690,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.111111111,"sars-cov-2, and, bat, pangolin, which"
26691,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.111111111,"sars-cov-2, and, bat, pangolin, viruses"
26692,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.111111111,"human, and, this, virus, the, of"
26693,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.111111111,"the, viruses, wild, and, of"
26694,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.111111111,"within, this, of, and, viruses, the"
26695,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.111111111,"of, viruses, natural, and, the"
26696,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.111111111,"a, in, of"
26697,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.111111111,"in, viruses, animal"
26698,The COVID-19 most likely developed from bat origin coronaviruses,"An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.111111111,"bat, coronaviruses"
26699,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.111111111,"bats, are, the, two, viruses, in"
26700,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.111111111,"or, bats, are, in"
26701,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.111111111,"bats, are, the, as"
26702,Coronaviruses account for over 30% of the world’s viruses.,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.111111111,"coronaviruses, over, of, the"
26703,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.111111111,"the, of, and, three, four"
26704,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.111111111,"bats, of, species, and"
26705,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.111111111,"the, of, and, animal, to"
26706,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.111111111,"of, and, are, species, the"
26707,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.111111111,"bats, for, coronavirus, of, virus, and, with, that"
26708,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.111111111,"to, bat, and"
26709,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.111111111,"bat, to, in"
26710,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.111111111,"coronaviruses, to, in, bat, and"
26711,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.111111111,"coronaviruses, to, in, and"
26712,"Malayan pangolins (Manis javanica)  

illegally imported into Guangdong province  

contain coronaviruses similar to SARS- 

CoV-22",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.111111111,"coronaviruses, similar, to"
26713,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.111111111,"and, similar, to, in, genetic, many"
26714,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.111111111,"sars-cov-2, and, which, to, of, in"
26715,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.111111111,"of, to, and, carry, sars-cov-2"
26716,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.111111111,"which, to, of, and"
26717,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.111111111,"sars-cov-2, and, to, which, sars-cov"
26718,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.111111111,"in, of, which, sars-cov-2, to"
26719,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.111111111,"sars-cov, and, sars-cov-2, more, than"
26720,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.111111111,"bats, of, and, species"
26721,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.111111111,"are, to, the, sars-"
26722,"Bats are natural hosts of many of the known  

coronaviruses","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.111111111,"are, many, the"
26723,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.111111111,"the, sars-, cov-2, viruses,"
26724,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.111111111,"the, and, to, sarbecovirus, are, sars-, cov-2"
26725,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.111111111,"is, identical, to, in"
26726,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.111111111,"virus, is, to, identical"
26727,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.111111111,"to, sars-cov-2, is, virus"
26728,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.111111111,"virus, to, in"
26729,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.111111111,"sars-cov-2, is, to, in"
26730,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.111111111,"sars-cov-2, is, virus, in"
26731,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.111111111,"a, coronavirus, is"
26732,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.111111111,"a, and, is"
26733,"the close relation  

between SARS coronavirus and 2019-nCoV","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.111111111,"coronavirus, and"
26734,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.111111111,"a, is, and"
26735,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.111111111,"of, in, bats"
26736,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.111111111,"bats, the, in, china"
26737,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.111111111,"human, sars-cov, and, to, bat, which"
26738,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.111111111,"and, have, from, the, bat, of"
26739,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.111111111,"from, the, to, have, with"
26740,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.111111111,"the, of, human, from, bat"
26741,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.111111111,"of, the, virus, and, with, bat"
26742,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.111111111,"the, of, from, and, which, with"
26743,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.111111111,"to, have, the, with, bat, which"
26744,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.111111111,"infected, to, with, the, of, sars-cov-2"
26745,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.111111111,"a, coronavirus, sars-cov-2, origin"
26746,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.111111111,"t, that, be, of"
26747,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.111111111,"that, sars-cov-2, a, origin"
26748,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.111111111,"t, be, that, coronavirus"
26749,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.111111111,"the, sars-cov-2, been, to, from, of"
26750,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.111111111,"from, the, of, that, sars-cov-2, have, to"
26751,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.111111111,"that, it, sars-cov-2, to, from, any, used"
26752,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.111111111,"the, of, sars-cov-2, been, to"
26753,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.111111111,"the, of, to, coronaviruses, from"
26754,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.111111111,"the, closest, to, sars-cov-2, from, of"
26755,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.111111111,"coronaviruses, to, sars-cov-2, the, including, that, of"
26756,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.111111111,"the, from, that, sars-cov-2, to, contains"
26757,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.111111111,"is, which, previously, from"
26758,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.111111111,"could, have, been, from, identified"
26759,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.111111111,"which, is, coronavirus, from"
26760,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.111111111,"it, been, from"
26761,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.111111111,"a, the, sars-cov-2, and, to, which, is"
26762,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.111111111,"coronaviruses, and, a, to, the, be, of, human"
26763,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.111111111,"found, in, the, of, which, sars-cov-2, to"
26764,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.111111111,"a, bat, found, in, of, sars-cov-2"
26765,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.111111111,"is, the, sars-cov-2, to, a, bat"
26766,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.111111111,"in, found, of, and, which, have, to"
26767,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.111111111,"in, the, virus, is, that, sars-cov-2, a"
26768,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.111111111,"that, and, virus, is"
26769,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.111111111,"emerged, with, that, sars-cov-2, and, genetic"
26770,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.111111111,"a, sars-cov-2, genetic, with"
26771,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.111111111,"the, of, to, that, and, bat"
26772,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.111111111,"all, that, are, to"
26773,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.111111111,"and, human, that, of, the"
26774,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.111111111,"that, of, to, and, are, the"
26775,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.111111111,"of, the, and, that, viruses"
26776,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.111111111,"that, the, and, bat, viruses"
26777,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.111111111,"with, genome, to, the"
26778,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.111111111,"bat, genome, with, sars-cov-2"
26779,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.111111111,"sars-cov-2, bat, to, the, that"
26780,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.111111111,"the, identical, to, sars-cov-2, that"
26781,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.111111111,"bat, the, host, sars-cov-2"
26782,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.111111111,"research, groups, highly, sars-cov-2, as"
26783,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.111111111,"that, it, was, sars-cov-2, to, is"
26784,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.111111111,"the, that, of, sars-cov-2, is, it"
26785,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.111111111,"and, bat, of, genome"
26786,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.111111111,"as, of, natural, origin"
26787,"Bats have been reported as being the rich source of 

coronaviruses","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.111111111,"been, as, of"
26788,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.111111111,"of, has, and, virus"
26789,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.111111111,"based, on, of, and, evolutionary"
26790,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.111111111,"natural, host, of"
26791,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.111111111,"of, natural, and, results"
26792,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.111111111,"of, a, sars-cov-like"
26793,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.111111111,"of, a, the, and"
26794,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.111111111,"human, and, virus, the, covid-19, was"
26795,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.111111111,"sars-cov-2, sequence, and, bat, to, 96.2%, that"
26796,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.111111111,"the, sequence, that, might, same"
26797,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.111111111,"the, genome, that, covid-19, virus"
26798,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.111111111,"many, such, as, in, and"
26799,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.111111111,"that, sequences, of, and, receptor, which, as"
26800,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.111111111,"in, similar, that, of, protein"
26801,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.111111111,"that, protein, of, pangolin, as, intermediate"
26802,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.111111111,"the, to, in, with, of"
26803,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.111111111,"the, is, bat, in"
26804,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.111111111,"bat, is, the, with, sars-cov-2"
26805,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.111111111,"to, sars-cov-2, the, genome,, of"
26806,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.111111111,"and, in, to, the, of, is, sars-cov-2"
26807,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.111111111,"sars-cov-2, of, genomic"
26808,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.111111111,"of, sars-cov-2, to, similar"
26809,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.111111111,"of, similar, genomic, to"
26810,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.111111111,"and, sars-cov-2, to, of, carry"
26811,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.111111111,"including, the, to, of, and"
26812,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.111111111,"its, the, of, that, sars-cov-2, to"
26813,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.111111111,"sars-cov-2, origin, and, animal, humans"
26814,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",hese reservoirs are the bats,0.111111111,"the, reservoirs"
26815,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.111111111,"the, has, bats, in, of"
26816,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.111111111,"the, most, of, zoonotic, host"
26817,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.111111111,"have, zoonotic, they, of, and"
26818,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.111111111,"of, the, are, as, viruses"
26819,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.111111111,"have, the, of, and, as, viruses"
26820,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.111111111,"the, host, of, been, zoonotic"
26821,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.111111111,"of, most, the, coronaviruses,, and"
26822,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.111111111,"bats, of, and, are, more, as, they"
26823,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.111111111,"they, the, most, of"
26824,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.111111111,"of, and, that, bats, for, virus, with, coronavirus"
26825,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.111111111,"that, the, be, a, host, of"
26826,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.111111111,"the, is, that, in, for, of, to, and, with, a, an"
26827,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.111111111,"that, be, for, are, in, an, with"
26828,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.111111111,"is, the, coronavirus, to, be, in, of"
26829,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.111111111,"that, was, to, and, is, in"
26830,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.111111111,"a, the, is, and, sequence, human"
26831,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.111111111,"human, to, in, and"
26832,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.111111111,"closest, to, similarity, is, the"
26833,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.111111111,"that, had, a, the, virus, was, human, in, discovered, to"
26834,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.111111111,"similarity, to, in, the, that, is"
26835,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.111111111,"is, the, and, similarity"
26836,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.111111111,"the, of, in, intermediate"
26837,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.111111111,"the, in, pangolins, of"
26838,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.111111111,"of, in, the, as"
26839,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.111111111,"the, sars-cov-2,, in, of"
26840,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.111111111,"of, sars-cov-2, humans, from, to"
26841,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.111111111,"the, of, from, close, to, as"
26842,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.111111111,"the, of, spillover, sars-cov-2, to"
26843,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.111111111,"has, and, the, of, in, china"
26844,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.111111111,"had, as, and, before, the, of, been, in"
26845,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.111111111,"that, the, of, people"
26846,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.111111111,"that, is, in, this"
26847,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.111111111,"the, of, suggested, that, to, this"
26848,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.111111111,"of, wet, market, in, that, animal, the, to"
26849,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.111111111,"on, were, to, of, in, the"
26850,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.111111111,"the, to, covid-19, is, likely"
26851,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.111111111,"in, a, to, market"
26852,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.111111111,"in, a, animal, to"
26853,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.111111111,"a, seafood, market, and, to"
26854,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.111111111,"a, in, and, to"
26855,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.111111111,"to, in, and, a, wuhan,, china"
26856,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.111111111,"a, of, to, and"
26857,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.111111111,"and, the, to, a"
26858,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.111111111,"a, sars-cov-2, and, the, of"
26859,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.111111111,"a, the, coronavirus, sars-cov-2"
26860,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.111111111,"and, the, be, spillover, of, sars-cov-2, a"
26861,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.111111111,"the, of, a, coronavirus"
26862,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.111111111,"be, a, transmission, to, of, and"
26863,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.111111111,"a, of, and, the, ability, to"
26864,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.111111111,"and, to, the, of, sars-cov-2, adapted, a"
26865,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.111111111,"the, and, a, ability, to, of"
26866,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.111111111,"species, of, bats, and, the"
26867,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.111111111,"of, bats, the, and, has, been, that"
26868,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.111111111,"and, that, of, the, most"
26869,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.111111111,"that, are, and, the, of"
26870,Bats are likely reservoir hosts for SARS-CoV-2,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.111111111,"bats, hosts"
26871,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.111111111,"the, bats, of, be"
26872,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.111111111,"the, of, bats, and"
26873,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.111111111,"bats, and, may, the"
26874,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.111111111,"of, and, the"
26875,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.111111111,"genomic, of, sars-cov-2"
26876,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.111111111,"of, the, sequence, sars-cov-2"
26877,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.111111111,"the, sars-cov-2, with, sequence, at"
26878,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.111111111,"is, previously, from, which"
26879,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.111111111,"in, to, is, the, which, was"
26880,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.111111111,"was, in, at, wuhan, province,"
26881,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.111111111,"the, in, from, was, at"
26882,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.111111111,"the, in, to, was, t"
26883,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",Bats are likely reservoir hosts for SARS-CoV-2,0.111111111,"are, bats, hosts, for"
26884,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",Bats are likely reservoir hosts for SARS-CoV-2,0.111111111,"sars-cov-2, bats"
26885,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.111111111,"a, origin, sars-cov-2, coronavirus"
26886,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.111111111,"sars-cov-2, to, with, the"
26887,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.111111111,"the, sars-cov-2, zoonotic, from"
26888,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.111111111,"the, isolated, from, a"
26889,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.111111111,"the, from, to, bats,"
26890,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.111111111,"to, the, sars-cov-2, origin, is"
26891,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.111111111,"is, to, origin, the, from"
26892,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.111111111,"and, to, of, which"
26893,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.111111111,"the, of, to, and, including"
26894,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.111111111,"was, in, the"
26895,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.111111111,"the, in, to, was"
26896,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.111111111,"to, other, bats,, and, in"
26897,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.111111111,"other, to, and, the"
26898,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.111111111,"in, the, outbreak, was"
26899,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.111111111,"in, from, the, humans"
26900,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.111111111,"the, china, in, markets, animals, sars-cov, was"
26901,SARS-CoV-2 was created from SARS-CoV-2,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.111111111,"was, from"
26902,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.111111111,"in, the, of, that"
26903,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.111111111,"is, the, that, in"
26904,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.111111111,"that, the, bat, is"
26905,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.111111111,"is, the, bat, in, protein"
26906,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.111111111,"the, in, sars-cov-2"
26907,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.111111111,"is, identical, to, the, that"
26908,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.111111111,"the, of, that, to, bat, and"
26909,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.111111111,"that, and, the, of"
26910,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.111111111,"the, that, reservoirs"
26911,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.111111111,"the, that, for, of"
26912,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.111111111,"that, the, of, bats"
26913,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","civet cats and raccoon dogs  

are the intermediate hosts",0.111111111,"the, are, hosts"
26914,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","civet cats and raccoon dogs  

are the intermediate hosts",0.111111111,"the, and, civet"
26915,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.111111111,"to, highly, any, and, was, the"
26916,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.111111111,"the, to, for, a, from, animals"
26917,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.111111111,"are, to, the, in, and, that, for"
26918,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.111111111,"the, that, with, at, and, to"
26919,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.111111111,"the, to, that, was, transmitted, from"
26920,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.111111111,"of, sars-cov-2, and, bats"
26921,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.111111111,"the, of, animal, and, sars-cov-2"
26922,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.111111111,"the, to, and, sars-cov-2"
26923,"Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.111111111,"of, dogs, animal"
26924,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.111111111,"to, sars-cov-2, of, bats, the, and"
26925,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.111111111,"and, can, the, of"
26926,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.111111111,"are, to, be"
26927,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.111111111,"the, bats, are, sars-cov-2"
26928,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.111111111,"sars-cov-2, the, of, been, to, from"
26929,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.111111111,"in, the, of, has, bats"
26930,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.111111111,"the, from, has, sars-cov-2"
26931,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.111111111,"the, has, in, bats"
26932,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.111111111,"the, been, from, in, to"
26933,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.111111111,"the, of, evidence, to, support, this"
26934,"This suggests that the BANAL series may be able to directly infect  

humans.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.111111111,"this, the, be, to"
26935,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.111111111,"is, from, to, through, in, been"
26936,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.111111111,"this, sars-cov-2, in, bats"
26937,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.111111111,"that, a, in"
26938,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.111111111,"the, a, which, that, and"
26939,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.111111111,"in, the, which, originated, and"
26940,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.111111111,"that, and, in, a"
26941,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.111111111,"that, the, and, which"
26942,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.111111111,"on, that, has, with, and, to"
26943,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.111111111,"identified, from, could, have, been"
26944,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.111111111,"a, are, to, bat, sars-cov-2, from"
26945,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.111111111,"several, studies, have, to, sars-cov-2"
26946,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.111111111,"bat, a, high, from, animal, species, as"
26947,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.111111111,"studies, have, a, in, as, china"
26948,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.111111111,"have, been, a, to, and, are, sars-cov-2"
26949,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.111111111,"have, been, to, sars-cov-2, as"
26950,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.111111111,"studies, sars-cov-2, likely, to, from"
26951,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.111111111,"as, natural, of, origin"
26952,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.111111111,"to, the, of, evidence, that, points"
26953,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.111111111,"emerged, that, the, of, as, sars-cov-2"
26954,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.111111111,"that, of, sars-cov-2, from, the"
26955,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.111111111,"that, the, of, sars-cov-2, as, a"
26956,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.111111111,"the, of, sars-cov-2, to, humans"
26957,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.111111111,"the, of, from, a, sars-cov-2"
26958,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.111111111,"of, the, sars-cov-2, from, origin"
26959,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.111111111,"a, the, that, sars-cov-2, from"
26960,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.111111111,"from, to, that, the, of, natural, sars-cov-2"
26961,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.111111111,"only, spread, the, that, sars-cov-2, have"
26962,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.111111111,"the, genome, sars-cov-2, has"
26963,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.111111111,"the, natural, sars-cov-2, and"
26964,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.111111111,"has, nucleotide, and, could"
26965,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.111111111,"that, the, and, have, are, sars-cov-2"
26966,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.111111111,"have, the, of, and, from, bat"
26967,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.111111111,"and, have, that, of, bat"
26968,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.111111111,"that, was, and, at, wuhan"
26969,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.111111111,"that, the, was, and, changes"
26970,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.111111111,"of, that, the, bat, from, these"
26971,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.111111111,"these, studies, have, of, the"
26972,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.111111111,"and, suggest, that, of, the"
26973,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.111111111,"suggest, that, have, of, and, the"
26974,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.111111111,"that, the, and, bat, ratg13"
26975,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.111111111,"studies, that, and, the, of"
26976,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.111111111,"ratg13, the, bat, coronavirus, of"
26977,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.111111111,"the, of, people, that"
26978,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.111111111,"the, of, that, sars-cov-2, spillover"
26979,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.111111111,"that, the, of, was"
26980,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.111111111,"sars-cov-2, the, that, result, of"
26981,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.111111111,"the, that, of, sars-cov-2, hypothesis"
26982,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.111111111,"coronaviruses,, with, sars-cov-2"
26983,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.111111111,"sars-cov-2, with, other"
26984,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.111111111,"of, sars-cov-2, bats, and"
26985,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.111111111,"sars-cov-2, from, to, a, are, bat"
26986,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.111111111,"the, of, that, from, to, bat"
26987,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.111111111,"the, of, from, two, sars-cov-2"
26988,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.111111111,"the, that, of, are, lineage, at"
26989,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.111111111,"the, that, viruses, from"
26990,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.111111111,"this, to, that, the, of"
26991,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.111111111,"a, of, that, sars-cov-2, by, the, and"
26992,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.111111111,"the, of, and, that, sars-cov-2, which, humans, by"
26993,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.111111111,"that, the, in, and, humans, from, at, a"
26994,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.111111111,"a, of, the, sars-cov-2, that, and, two"
26995,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.111111111,"sars-cov-2, the, viruses, in, zoonotic, and, of"
26996,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.111111111,"in, a, of, the, from, which, circulating, this, two, and, at, viruses, were"
26997,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.111111111,"the, most, of, host, zoonotic"
26998,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.111111111,"the, from, sars-cov-2, zoonotic"
26999,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.111111111,"most, the, of, intro-, from"
27000,"this one jumped from bats origin  

into humans","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.111111111,"from, into, humans"
27001,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.111111111,"the, to, and, that, sars-cov-2"
27002,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.111111111,"the, animals, that, be, sars-cov-2"
27003,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.111111111,"to, the, of, animals, market, that"
27004,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.111111111,"to, the, huanan, market"
27005,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.111111111,"the, to, that, of, animals"
27006,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.111111111,"the, and, to, that, sars-cov-2, of, are"
27007,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.111111111,"the, animal, of, sars-cov-2, and"
27008,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.111111111,"the, of, and, in, with, sars-cov-2"
27009,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.111111111,"the, cases, and, huanan, market, of"
27010,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.111111111,"the, of, clustering, that, sars-cov-2, with"
27011,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.111111111,"to, a, market, in"
27012,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.111111111,"the, we, that, are, more"
27013,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.111111111,"in, to, that, the"
27014,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.111111111,"in, to, closely, related, that, the, are"
27015,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.111111111,"and, the, lineage, of"
27016,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.111111111,"the, of, with, a, and"
27017,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.111111111,"the, this, in, with, of"
27018,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.111111111,"the, lineage, is, in"
27019,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.111111111,"at, this, is, the, with"
27020,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.111111111,"the, of, a, huanan, market"
27021,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.111111111,"the, virus, of, lineage"
27022,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.111111111,"from, the, of, virus"
27023,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.111111111,"et, al., the, of"
27024,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.111111111,"of, the, was, by"
27025,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.111111111,"the, most, intro-, of, from"
27026,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.111111111,"in, outbreaks, the, animal, other"
27027,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.111111111,"other, outbreaks, in, the, animal"
27028,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.111111111,"because, to, the, viruses, in"
27029,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.111111111,"sars-cov-2, animal, and, the"
27030,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.111111111,"and, likely, in, animal"
27031,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.111111111,"that, was, likely, the, sars-cov-2, and"
27032,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.111111111,"the, market, than, in, that"
27033,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.111111111,"at, that, the, was"
27034,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.111111111,"that, sars-cov-2, animal, and"
27035,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.111111111,"sars-cov-2, in, animal, and, that, the"
27036,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.111111111,"that, and, sars-cov-2, than, the, in"
27037,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.111111111,"sars-cov-2, and, the, that, in"
27038,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.111111111,"in, the, sars-cov-2, at, that"
27039,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.111111111,"animal, likely, in, and"
27040,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.111111111,"to, of, sars-cov-2, from, humans"
27041,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.111111111,"and, in, were, at, on"
27042,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.111111111,"of, two, in, and, sars-cov-2"
27043,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.111111111,"sars-cov-2, to, and, on, of"
27044,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.111111111,"still, a, that, sars-cov-2, from"
27045,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.111111111,"all, that, sars-cov-2, a"
27046,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.111111111,"the, in, that, chinese"
27047,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.111111111,"and, that, the, was, of"
27048,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.111111111,"to, that, and, was, the"
27049,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.111111111,"of, the, covid-19, and, was"
27050,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.111111111,"the, was, to, than"
27051,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.111111111,"the, and, to, were"
27052,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.111111111,"sars-cov-2, the, of, that, have, to, from"
27053,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.111111111,"that, sars-cov-2, only, have, spread, the"
27054,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.111111111,"that, sars-cov-2, the, of, spillover"
27055,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.111111111,"that, have, in, different, animals, from"
27056,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.111111111,"the, have, from, in, to, may"
27057,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.111111111,"to, the, of, may, a, spillover"
27058,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.111111111,"to, of, have, from, a, sars-cov-2"
27059,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.111111111,"a, that, the, sars-cov-2, in, samples"
27060,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.111111111,"the, to, a, from, animals, also"
27061,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.111111111,"that, sars-cov-2, from, a, to, in"
27062,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.111111111,"that, sars-cov-2, may, have, in"
27063,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.111111111,"sars-cov-2, any, that, used, to, it, from"
27064,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.111111111,"was, that, sars-cov-2, is, to, it"
27065,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.111111111,"is, to, that, in, and, was"
27066,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.111111111,"that, in, other, and, from, there"
27067,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.111111111,"sars-cov-2, from, that, is, in"
27068,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.111111111,"there, is, that, viruses, to, sars-cov-2"
27069,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.111111111,"to, that, are, sars-cov-2, in, and"
27070,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.111111111,"to, that, sars-cov-2, was, not, from"
27071,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.111111111,"there, no, the, institute, of, had, viruses, to"
27072,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.111111111,"evidence, that, in, a"
27073,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.111111111,"evidence, that, wiv"
27074,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.111111111,"sars-cov-2, is, in, or"
27075,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.111111111,"the, to, that, are, most, closely, related, sars-cov-2, in, and"
27076,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.111111111,"evidence, that, a, in"
27077,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.111111111,"the, a, genome, to, that, from"
27078,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.111111111,"in, from, to, the, humans"
27079,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.111111111,"a, that, the, to, in"
27080,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.111111111,"evidence, that, the, a, from, as"
27081,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.111111111,"the, two, in, that, a"
27082,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.111111111,"that, genome, to, a, the"
27083,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.111111111,"this, of, to, the, market, in, that, virus"
27084,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.111111111,"is, a, virus, that, found, to, the, for"
27085,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.111111111,"the, live, from, march, were, in, of, a, as, to, we, that, positive, virus"
27086,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.111111111,"sars-cov-2., this, is, we, to, the, that, in"
27087,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.111111111,"most, that, a, the, of, and, is, but, we"
27088,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.111111111,"is, a, virus, that, found, on, the, most"
27089,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.111111111,"a, that, the, is, of, and, animals"
27090,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.111111111,"to, a, animal, in"
27091,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.111111111,"a, in, that, to"
27092,Genetic evidence suggesting otherwise is yet to be presented.,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.111111111,"evidence, is, to"
27093,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.111111111,"the, sars-cov-2, was, likely, that, and"
27094,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.111111111,"a, the, of, and, we, that, but, is, most"
27095,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.111111111,"origins, and, the, was, to, a"
27096,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.111111111,"the, likely, to, that, and, naturally"
27097,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.111111111,"that, of, to, an, is, a, sars-cov-2, the"
27098,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.111111111,"we, sars-cov-2, the, and, that, of, is"
27099,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.111111111,"and, to, the, evidence, of, sars-cov-2, is"
27100,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.111111111,"is, to, the, that, an, and, but"
27101,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.111111111,"evidence, to, the, points, that, of"
27102,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.111111111,"the, market, animals, that, to, of"
27103,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.111111111,"samples, the, market, that, of, for"
27104,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.111111111,"as, of, and"
27105,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.111111111,"of, such, as, and"
27106,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.111111111,"that, with, has, on, and, to"
27107,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.111111111,"the, was, to, as"
27108,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.111111111,"the, as, a, and"
27109,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.111111111,"coronavirus, a, and, with, has, to, the"
27110,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.111111111,"the, that, a, virus"
27111,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.111111111,"a, the, has, that, to, virus"
27112,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.111111111,"similarity, to, a, was, bat"
27113,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.111111111,"the, with, and, to"
27114,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.111111111,"the, with, and, similarity"
27115,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.111111111,"samples, from, the, that"
27116,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.111111111,"the, also, that, virus"
27117,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.111111111,"this, that, the, and"
27118,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.111111111,"they, have, of, and, zoonotic"
27119,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.111111111,"to, a, of, and"
27120,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.111111111,"that, of, to, a, and"
27121,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.111111111,"all, that, of, a"
27122,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.111111111,"all, that, a, and"
27123,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.111111111,"that, of, and, to"
27124,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.111111111,"a, that, of, and"
27125,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.111111111,"from, in, different, that, animals, have"
27126,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.111111111,"there, that, other, from, and, in"
27127,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.111111111,"from, animals, in, have"
27128,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.111111111,"in, different, and, all, cov, that, origin"
27129,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.111111111,"the, and, natural, bat,, host"
27130,"The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.111111111,"the, and, host"
27131,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.111111111,"is, to, human, and"
27132,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.111111111,"human, from, to, and"
27133,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.111111111,"to, from, animals, is"
27134,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.111111111,"the, coronavirus, and, bat"
27135,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.111111111,"the, bat, and, sequence"
27136,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.111111111,"bat, and, to, the"
27137,The COVID-19 most likely developed from bat origin coronaviruses,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.111111111,"the, covid-19, bat"
27138,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.111111111,"the, first, was, to, that"
27139,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.111111111,"was, to, that, the"
27140,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.111111111,"was, the, of, to"
27141,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.111111111,"the, was, as, to"
27142,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.111111111,"to, the, be, intermediate, host"
27143,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.111111111,"the, of, to, as"
27144,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.111111111,"the, of, to, was"
27145,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.111111111,"a, of, the, in, bats"
27146,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.111111111,"in, a, of"
27147,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.111111111,"a, of, the, in, with"
27148,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.111111111,"the, of, possible"
27149,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.111111111,"the, with, in, a, of"
27150,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.111111111,"the, in, a, of"
27151,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.111111111,"in, the, of, with, a"
27152,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.111111111,"with, in, nature"
27153,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.111111111,"a, of, the, in"
27154,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.111111111,"the, of, a, with"
27155,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.111111111,"in, a, of, to, the, that, were, market"
27156,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.111111111,"the, of, and, that, a, in, to"
27157,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.111111111,"the, of, to, a, high, and"
27158,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.111111111,"that, of, to, a, in, with, the"
27159,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.111111111,"the, of, that, in, a, and, to"
27160,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.111111111,"the, indicates, that, to, and"
27161,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.111111111,"the, and, a, in, to, that, of"
27162,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.111111111,"the, market, than, that, in"
27163,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.111111111,"in, of, to, the, virus, that, this, market"
27164,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.111111111,"the, virus, to, market, in"
27165,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.111111111,"been, to, that, in"
27166,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.111111111,"the, of, that, virus, in, this, or, to"
27167,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.111111111,"of, virus, that, to, the"
27168,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.111111111,"had, to, this, the, of, that, been, in"
27169,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.111111111,"by, in, the, with"
27170,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.111111111,"the, of, et, al., as, to, this"
27171,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.111111111,"virus, is, identical, to"
27172,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.111111111,"is, coronavirus, from, which"
27173,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.111111111,"to, that, the, of, from"
27174,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.111111111,"to, from, of, the, and, has, that"
27175,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.111111111,"is, that, of, coronavirus"
27176,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.111111111,"and, the, of, which, that"
27177,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.111111111,"that, the, and, is, which"
27178,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.111111111,"is, the, coronavirus, to, of"
27179,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.111111111,"virus, is, to, sars-cov-2"
27180,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.111111111,"that, the, be, a"
27181,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.111111111,"the, from, that, intermediate, was"
27182,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.111111111,"bats, as, the, and"
27183,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.111111111,"the, sars-cov-2, to, is, a, that"
27184,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.111111111,"using, the, that, bats, sars-cov-2"
27185,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.111111111,"and, to, bat, pangolin, a, which"
27186,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.111111111,"the, that, a, genome, to, from"
27187,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.111111111,"the, covid-19, of, to, a, virus"
27188,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.111111111,"that, the, of, bat, covid-19, a, to"
27189,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.111111111,"the, covid-19, and, of, a, to"
27190,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.111111111,"to, the, with, bat, pangolin, which"
27191,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Bats have been reported as being the rich source of 

coronaviruses",0.111111111,"coronaviruses, bats, the"
27192,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Bats have been reported as being the rich source of 

coronaviruses",0.111111111,"the, of, have, as"
27193,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.111111111,"to, have, with, the, from"
27194,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.111111111,"to, the, sars-cov-2, from"
27195,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.111111111,"the, has, been"
27196,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.111111111,"from, to, sars-cov-2, the"
27197,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.111111111,"has, the, with, sars-cov-2"
27198,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.111111111,"has, been, sars-cov-2"
27199,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.111111111,"the, sars-cov-2, a, with"
27200,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.111111111,"the, similarity, sars-cov-2, pangolin"
27201,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.111111111,"sars-cov-2, to, from"
27202,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.111111111,"of, the, to, infected, with, sars-cov-2"
27203,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.111111111,"the, similar, to, and"
27204,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.111111111,"the, of, to, sars-cov-2, with, and"
27205,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.111111111,"with, and, similar, to, sars-cov-2, the"
27206,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.111111111,"to, sars-cov-2, and, pangolins, from"
27207,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.111111111,"the, and, to, humans, of"
27208,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.111111111,"and, of, sars-cov-2, their, the, to"
27209,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.111111111,"to, the, of, from, with"
27210,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.111111111,"the, sars-cov-2, has, from"
27211,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.111111111,"the, isolated, from"
27212,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.111111111,"sars-cov-2, the, from"
27213,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.111111111,"the, has, bat"
27214,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.111111111,"bat, coronavirus, sars-cov-2, the"
27215,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.111111111,"the, sars-cov-2, with"
27216,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.111111111,"virus, and, has, of"
27217,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.111111111,"a, of, the, by, that, sars-cov-2, and"
27218,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.111111111,"sars-cov-2, to, date, the"
27219,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.111111111,"of, the, has, and"
27220,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.111111111,"a, sars-cov-2, genetic, the"
27221,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.111111111,"genetic, of, the, available"
27222,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.111111111,"the, to, that, has, of"
27223,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.111111111,"the, by, and, to, that, sars-cov-2, of"
27224,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.111111111,"a, the, that, sars-cov-2, originated"
27225,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.111111111,"that, pangolin-cov, the, of, to"
27226,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.111111111,"bat, to, and"
27227,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.111111111,"to, and, the, of"
27228,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.111111111,"the, pangolin, and, of"
27229,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.111111111,"the, to, human"
27230,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.111111111,"the, and, is, one, to"
27231,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.111111111,"of, and, the, between, bat"
27232,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.111111111,"the, is, and"
27233,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.111111111,"of, and, to, the, animal"
27234,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.111111111,"based, on, and, evolutionary, of"
27235,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.111111111,"of, the, by, that, sars-cov-2, and, which, humans"
27236,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.111111111,"analysis, the, was, to, which, of, and"
27237,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.111111111,"is, to, have, the, on"
27238,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.111111111,"the, was, to, have, that, of"
27239,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.111111111,"the, by, and, to, that, sars-cov-2, is, of"
27240,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.111111111,"to, a, and, the"
27241,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.111111111,"to, the, a, from"
27242,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.111111111,"a, was, the, and, to, origins"
27243,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.111111111,"to, the, market, in, virus"
27244,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.111111111,"the, virus, was, a"
27245,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.111111111,"a, virus, its, to, the"
27246,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.111111111,"a, the, from, that, and, at, in, humans"
27247,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.111111111,"have, through, that, the, to"
27248,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.111111111,"to, the, of, covid-19"
27249,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.111111111,"that, through, to, the, most"
27250,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.111111111,"that, the, covid-19, of"
27251,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.111111111,"is, the, to, which, was, in"
27252,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.111111111,"the, and, which, originated, in"
27253,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.111111111,"of, the, covid-19, virus, and, was"
27254,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.111111111,"the, was, transmitted, to, animals"
27255,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.111111111,"the, of, covid-19, in, but, to, genetic"
27256,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.111111111,"the, virus, in, animals, which, they"
27257,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.111111111,"bats, to, is, and, the"
27258,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.111111111,"is, to, originated, in, the, which"
27259,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.111111111,"the, of, is, and, but"
27260,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.111111111,"the, of, is, virus, has, in"
27261,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.111111111,"to, in, that, been"
27262,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.111111111,"has, to, in"
27263,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.111111111,"has, been, in, to, that"
27264,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.111111111,"been, in, that"
27265,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.111111111,"the, at, was, that"
27266,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.111111111,"a, at, the, of, virus, that, is"
27267,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.111111111,"all, a, that, of"
27268,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.111111111,"of, the, as, a"
27269,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.111111111,"the, of, that, virus, a, evidence, as"
27270,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.111111111,"all, the, that, of, is"
27271,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.111111111,"the, of, a, as"
27272,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.111111111,"no, the, evidence, of, is"
27273,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.111111111,"that, naturally, likely, the, and, to"
27274,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.111111111,"that, natural, origin, and"
27275,"this one jumped from bats origin  

into humans","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.111111111,"jumped, origin, humans"
27276,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.111111111,"that, and, to, humans, the, in"
27277,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.111111111,"in, humans, that, the, and"
27278,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.111111111,"that, the, and, animals"
27279,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.111111111,"natural, origin, more, likely"
27280,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.111111111,"and, to, the, that, in"
27281,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.111111111,"in, the, to, that, virus"
27282,hese reservoirs are the bats,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.111111111,"reservoirs, the"
27283,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.111111111,"similar, to, and, the"
27284,hese close genetic relations suggest that they all have their ecological origin in bat populations,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.111111111,"that, origin, in"
27285,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.111111111,"the, virus, to"
27286,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.111111111,"in, and, similar, to, the"
27287,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.111111111,"the, virus, to, is"
27288,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.111111111,"that, to, in, and"
27289,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.111111111,"in, to, animal"
27290,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.111111111,"and, in, is, the, to"
27291,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.111111111,"that, the, origin"
27292,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.111111111,"the, and, similar, to, in, virus"
27293,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.111111111,"the, outbreak, was, in"
27294,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.111111111,"the, and, huanan, seafood, of"
27295,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.111111111,"the, of, huanan, seafood, and, in"
27296,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.111111111,"the, with, and, fall, also"
27297,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.111111111,"with, bat, cov, and"
27298,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.111111111,"the, with, and"
27299,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.111111111,"the, and, cov"
27300,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.111111111,"t, be, that, of"
27301,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.111111111,"that, virus, to, and, the"
27302,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.111111111,"the, zoonotic, to, of, and"
27303,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.111111111,"the, of, and, that, sequence, to"
27304,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.111111111,"that, of, bats, to, is, the"
27305,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.111111111,"t, bats, and"
27306,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.111111111,"the, of, and, that, virus, sequence, to"
27307,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.111111111,"the, and, that, of, is"
27308,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.111111111,"be, virus, to, bats, of, and"
27309,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.111111111,"that, bats, be, the"
27310,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.111111111,"the, bat,, natural, host, and"
27311,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.111111111,"the, intermediate, host, to, be"
27312,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.111111111,"(or, intermediate, and, may, the, or"
27313,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.111111111,"a, is, the, sequence, human, and"
27314,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.111111111,"a, of, wild, positive, for, with, palm, civet, the"
27315,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.111111111,"a, sequence, identity, with, the, bat"
27316,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.111111111,"the, sequence, of, identity, sars-cov, and"
27317,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.111111111,"infected, or, the"
27318,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.111111111,"have, in, animals, from"
27319,"Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.111111111,"or, the, infected"
27320,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.111111111,"may, from, in"
27321,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.111111111,"in, the, however,, not"
27322,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.111111111,"the, analysis, revealed, that, sars-cov-2"
27323,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.111111111,"the, that, reservoir, be"
27324,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.111111111,"related, to, genomic, sars-cov-2, the, bat"
27325,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.111111111,"that, related, to, sars-cov-2, bats"
27326,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.111111111,"analysis, that, sars-cov-2, the, to"
27327,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.111111111,"however,, the, not, in"
27328,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.111111111,"in, the, that, was, virus"
27329,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.111111111,"in, the, that, it, not"
27330,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.111111111,"however,, the, that, virus, in"
27331,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.111111111,"in, the, of, it, that, with, a"
27332,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.111111111,"of, with, a, wuhan, the, market, were, in"
27333,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.111111111,"that, the, in, wuhan, seafood, of"
27334,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.111111111,"a, of, patients, the, in, china"
27335,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.111111111,"the, isolated, from, that, hosts, for"
27336,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.111111111,"sars-cov-2, the, of, been, to"
27337,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.111111111,"sars-cov-2, has, the, genome"
27338,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.111111111,"the, been, human, to"
27339,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.111111111,"the, identical, to, of"
27340,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.111111111,"the, of, 80%, to"
27341,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.111111111,"of, to, the"
27342,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.111111111,"sars-cov-2, to, the"
27343,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.111111111,"to, sars-cov-2, the, of"
27344,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.111111111,"sars-cov, and, sars-cov-2, to, which"
27345,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.111111111,"the, sars-cov-2, and, which, to, a, is"
27346,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.111111111,"the, which, that, sars-cov-2, was, to"
27347,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.111111111,"the, also, to, sars-cov-2, by"
27348,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.111111111,"the, host, was, confirmed, a, that, to, and"
27349,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.111111111,"sars-cov-2, a, and, was, host"
27350,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.111111111,"the, host, for, sars-cov-2"
27351,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.111111111,"also, a, for, the, and"
27352,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.111111111,"of, to, be, the, animal"
27353,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.111111111,"the, to, be, sars-cov, of, cov,, for"
27354,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.111111111,"of, the, coronavirus, bat, human"
27355,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.111111111,"the, of, to, be, is, for"
27356,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.111111111,"animal, the, for, previous, more"
27357,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.111111111,"bat, is, the, more, for, than"
27358,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.111111111,"study, the, s, of, to, sars-cov-2."
27359,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.111111111,"with, the, sars-cov, and, to, of"
27360,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.111111111,"the, analysis, of, and, which, was, to"
27361,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.111111111,"the, of, to, cov,, for, sars-cov, be"
27362,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.111111111,"analysis, of, the, with, sars-cov, and"
27363,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.111111111,"with, the, of, bats, as, for, and"
27364,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.111111111,"the, was, at, and, to, of, with"
27365,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.111111111,"rbd, of, was, to, which, the"
27366,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.111111111,"bats, the, for, of, sars-cov, and"
27367,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.111111111,"to, in, human, and"
27368,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.111111111,"human, in, to, and"
27369,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.111111111,"hosts, and, humans"
27370,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.111111111,"to, in, can, human"
27371,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.111111111,"to, all, in, and"
27372,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.111111111,"sars-cov-2, genetic, with, and, that, emerged"
27373,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.111111111,"the, that, sars-cov-2, emerged, as, of"
27374,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.111111111,"as, and, the, of, et, al.,, that, sars-cov-2"
27375,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.111111111,"he, with, sars-cov-2, the, sequence, of, viral"
27376,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.111111111,"nucleotide, of, sars-cov-2, and, sars-cov, bat"
27377,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.111111111,"that, the, of, sars-cov, and, mers-cov"
27378,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.111111111,"sars-cov-2, and, bat, similarity, the, of"
27379,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.111111111,"the, of, from, bat, human"
27380,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.111111111,"from, it, been"
27381,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.111111111,"the, of, from, that"
27382,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.111111111,"it, that, of"
27383,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.111111111,"it, that, of, the"
27384,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.111111111,"of, that, the, bat, from"
27385,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.111111111,"human, that, of, the"
27386,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.111111111,"of, that, the, bat"
27387,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.111111111,"that, been, of, are, the"
27388,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.111111111,"et, of, genome, and, have, to"
27389,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.111111111,"sars-cov-2, have, to, several, studies"
27390,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.111111111,"are, the, as, of, viruses"
27391,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.111111111,"the, a, isolated, from"
27392,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.111111111,"from, in, the, of, those"
27393,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.111111111,"and, that, have, bat, of"
27394,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.111111111,"that, most, of, and, is"
27395,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.111111111,"the, has, bats, in"
27396,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.111111111,"the, most, bats, in"
27397,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",Many of these CoVs can infect several animal species as well,0.111111111,"of, species, animal"
27398,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",Many of these CoVs can infect several animal species as well,0.111111111,"many, as, well"
27399,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.111111111,"a, that, transmitted, from, to"
27400,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.111111111,"that, an, to, from, is"
27401,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.111111111,"is, to, from"
27402,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.111111111,"to, from, an, a"
27403,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.111111111,"is, virus, to"
27404,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.111111111,"to, zoonotic, virus"
27405,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.111111111,"from, that, to, a"
27406,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.111111111,"the, virus, a, to"
27407,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.111111111,"to, the, a, spillover"
27408,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.111111111,"to, a, the, for"
27409,"Bats have been reported as being the rich source of 

coronaviruses","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.111111111,"bats, the, coronaviruses"
27410,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.111111111,"to, date, sars-cov-2, the"
27411,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.111111111,"the, bats, to, humans, from"
27412,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.111111111,"sars-cov-2, coronaviruses, from, bat, to, bats"
27413,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.111111111,"the, from, in, to"
27414,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.111111111,"the, to, sars, of"
27415,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.111111111,"from, is, in"
27416,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.111111111,"of, in, sars, the, to, closely, related"
27417,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.111111111,"bats, of, related, to, cause, in"
27418,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.111111111,"suggest, that, they, in"
27419,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.111111111,"the, rhinolophus, and, in"
27420,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.111111111,"are, and, in, the"
27421,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.111111111,"are, in, and"
27422,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.111111111,"the, been, to, from, in"
27423,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.111111111,"from, in, the, may, have, to"
27424,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.111111111,"and, from, to, human"
27425,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.111111111,"the, been, to, human"
27426,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.111111111,"the, in, to, from"
27427,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.111111111,"the, to, in, from, an"
27428,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.111111111,"the, and, been, in"
27429,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.111111111,"the, human, in, to, market"
27430,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.111111111,"the, virus, an, animal, into, human, or, in, have, to"
27431,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.111111111,"the, been, or, have, to, virus"
27432,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.111111111,"the, and, have, been"
27433,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.111111111,"an, to, and, could"
27434,"Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.111111111,"is, a, and"
27435,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.111111111,"that, a, origin, sars-cov-2"
27436,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.111111111,"sars-cov-2, animal, that, and"
27437,"All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.111111111,"all, that, a, sars-cov-2"
27438,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.111111111,"all, a, that, and"
27439,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.111111111,"natural, origin, that, and"
27440,"expended to make the simple point 

that COVID-19 had a natural origin.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.111111111,"that, a, natural"
27441,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.111111111,"is, origin, that, has, and"
27442,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.111111111,"bats, most, sars-"
27443,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.111111111,"in, sars-, cov-2"
27444,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.111111111,"sars-, cov-2, in"
27445,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.111111111,"is, the, that, and"
27446,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.111111111,"that, sars-cov-2, and, the"
27447,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.111111111,"the, from, sars-cov-2"
27448,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.111111111,"infected, sars-cov-2, the"
27449,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.111111111,"the, that, sars-cov-2, from"
27450,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.111111111,"of, that, sars-cov-2, is, to"
27451,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.111111111,"to, be, likely, of, intermediate"
27452,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.111111111,"and, species, to, an, of"
27453,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.111111111,"transmission, an, animal, more, likely"
27454,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.111111111,"of, lineage, virus, the"
27455,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.111111111,"that, of, to, and"
27456,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.111111111,"the, of, to, that"
27457,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.111111111,"the, analyses, of, and, that, to"
27458,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.111111111,"that, the, of, coronavirus"
27459,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.111111111,"the, of, indicated, that, and, to"
27460,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.111111111,"with, the, of, and, bat, virus"
27461,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.111111111,"batcov, was, the, bat"
27462,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.111111111,"of, virus, with, ratg13,, and, the"
27463,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.111111111,"other, genome, and, the, of"
27464,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.111111111,"human, and, of, this, the, virus"
27465,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.111111111,"virus, the, covid-19, was, and, human"
27466,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.111111111,"of, the, and, with, human"
27467,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.111111111,"in, the, with, was, of"
27468,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.111111111,"the, of, with, human, ace2"
27469,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.111111111,"the, was, this, in, with, of"
27470,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.111111111,"detected, in, was, of, the"
27471,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",COVID-19 is a zoonotic virus,0.111111111,"is, a, covid-19, virus"
27472,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",COVID-19 is a zoonotic virus,0.111111111,"zoonotic, a, virus"
27473,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.111111111,"to, with, genome, the"
27474,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.111111111,"of, virus, the, from"
27475,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.111111111,"the, of, covid-19, to"
27476,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.111111111,"of, from, bats, to, with, the"
27477,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.111111111,"the, of, genome, covid-19"
27478,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.111111111,"the, from, covid-19, to"
27479,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.111111111,"be, virus, from, to, bats, of"
27480,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.111111111,"and, in, many, such, as"
27481,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.111111111,"that, the, are, to"
27482,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.111111111,"to, that, the, and"
27483,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.111111111,"viruses, and, to, the"
27484,"zoonotic corona- 

viruses have become an increasing threat to human health,","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.111111111,"zoonotic, viruses, to"
27485,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.111111111,"that, are, the, and"
27486,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.111111111,"and, coronaviruses, to, the"
27487,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.111111111,"the, and, to, be, a, of, human, coronaviruses"
27488,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.111111111,"the, of, palm, as, intermediate, a, to, human, and"
27489,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.111111111,"is, that, of, sars-cov-2, to"
27490,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.111111111,"the, of, to, that, sars-cov-2, is"
27491,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.111111111,"of, to, results, the"
27492,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.111111111,"similar, to, the, coronavirus, of, that"
27493,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.111111111,"with, and, of, the"
27494,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.111111111,"the, bat, coronavirus, and"
27495,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.111111111,"of, has, the, and"
27496,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.111111111,"the, of, coronavirus, human, bat"
27497,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.111111111,"human, and, with, the, of"
27498,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.111111111,"the, and, of, bat"
27499,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.111111111,"close, to, the, of, from, as"
27500,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.111111111,"to, bat, that, the, of, from"
27501,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.111111111,"the, of, very, to, that, was"
27502,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.111111111,"that, genome, to, and, the, of"
27503,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.111111111,"such, that, very, to, from"
27504,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.111111111,"the, bat, coronavirus, to, sequence, of"
27505,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.111111111,"the, of, that, to, covid-19"
27506,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.111111111,"the, of, sars, to"
27507,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.111111111,"approximately, of, the, covid-19, to"
27508,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.111111111,"the, virus, to, covid-19"
27509,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.111111111,"of, the, has, that, to, virus"
27510,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.111111111,"has, identity, to, and"
27511,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.111111111,"identity, of, with"
27512,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.111111111,"that, the, from, a, and"
27513,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.111111111,"the, and, on, that, a"
27514,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.111111111,"the, not, that, sars-cov-2, and, a"
27515,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.111111111,"that, sars-cov-2, a, the, genome, from"
27516,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.111111111,"analysis, that, sars-cov-2, the, and"
27517,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.111111111,"sars-cov-2, or, in"
27518,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.111111111,"in, ace2, to, sars-cov-2"
27519,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.111111111,"sars-cov-2, in, animal"
27520,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.111111111,"the, that, is, bat"
27521,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.111111111,"between, and, that, the"
27522,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.111111111,"the, virus, and, of"
27523,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.111111111,"the, covid-19, of, and"
27524,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.111111111,"a, and, that, the, from, in"
27525,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.111111111,"the, that, and, from, a"
27526,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.111111111,"in, the, to, that, and, a"
27527,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.111111111,"the, from, market, to"
27528,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.111111111,"the, live, animals, to, in, a, spread, that, and, market"
27529,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.111111111,"that, to, in, and, from"
27530,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.111111111,"in, transmitted, to, humans"
27531,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.111111111,"studies, that, to, in, humans"
27532,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.111111111,"a, the, outbreak, in, wuhan,"
27533,"Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution","the close relation  

between SARS coronavirus and 2019-nCoV",0.111111111,"and, coronavirus"
27534,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.111111111,"at, was, in, province,, wuhan"
27535,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.111111111,"and, a, that, in"
27536,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.111111111,"and, that, was, at, wuhan"
27537,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.111111111,"were, at, in, and, on"
27538,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.111111111,"and, were, in, china"
27539,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.111111111,"at, a, and, in, that"
27540,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.111111111,"first, was, in, that"
27541,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.111111111,"the, of, identical, to"
27542,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.111111111,"has, the, in, of, and, china"
27543,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.111111111,"the, of, in, with, a, and"
27544,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.111111111,"sars-cov-2, in, a, of, and, the, with"
27545,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.111111111,"sars-cov-2, and, bat, the, between, in"
27546,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.111111111,"sars-cov-2, has, the, with, bat"
27547,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.111111111,"that, in, is, this"
27548,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.111111111,"that, sars-cov-2, from, is, in"
27549,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.111111111,"from, in, may"
27550,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.111111111,"in, is, from"
27551,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.111111111,"sars-cov-2, a, from"
27552,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.111111111,"a, in, bat"
27553,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.111111111,"is, from, in"
27554,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.111111111,"sars-cov-2, in, this, that, is"
27555,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.111111111,"a, from, bat, in"
27556,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.111111111,"in, sars-cov-2, bat, this, that, is"
27557,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.111111111,"the, isolated, from, for, that, hosts"
27558,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.111111111,"the, pangolin, most, likely, intermediate"
27559,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.111111111,"a, in, the, s, protein, for"
27560,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.111111111,"the, of, likely, that, hosts, for"
27561,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.111111111,"the, for, a, from, most, likely"
27562,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.111111111,"genome, the, and, that, sars-cov-2"
27563,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.111111111,"a, of, the, that, sars-cov-2, and, two"
27564,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.111111111,"analysis, the, sars-cov, with, of, and"
27565,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.111111111,"revealed, that, of, sars-cov-2, the"
27566,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.111111111,"a, sars-cov-2, with, the"
27567,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.111111111,"two, the, and, with"
27568,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.111111111,"that, the, of, with"
27569,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.111111111,"two, of, the, sars-cov-2, and"
27570,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.111111111,"that, the, of, in, to, a, and"
27571,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.111111111,"analyses, that, the, of, and, to"
27572,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.111111111,"the, degree, of, ratg13, to, in"
27573,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.111111111,"genome, sequences, in, the, bat, of, and"
27574,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.111111111,"the, sars-cov-2, humans, of"
27575,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.111111111,"the, animal, and, of, sars-cov-2"
27576,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.111111111,"humans, and, hosts"
27577,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.111111111,"the, are, of, and"
27578,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.111111111,"the, of, humans, infectious"
27579,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.111111111,"the, and, sars-cov-2"
27580,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.111111111,"the, are, to, sars-"
27581,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.111111111,"sars-, most, bats"
27582,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.111111111,"likely, of, to, intermediate, be"
27583,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.111111111,"of, the, sars-cov-2, that, revealed"
27584,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.111111111,"sars-cov-2, the, for, wild, of"
27585,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.111111111,"of, sars-cov-2, which, the, animals"
27586,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","Bats are natural hosts of many of the known  

coronaviruses",0.111111111,"the, many, are"
27587,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Bats are natural hosts of many of the known  

coronaviruses",0.111111111,"the, known, of"
27588,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Bats are natural hosts of many of the known  

coronaviruses",0.111111111,"the, of, bats, natural"
27589,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Bats are natural hosts of many of the known  

coronaviruses",0.111111111,"of, natural, the"
27590,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.111111111,"to, bat, and, 96.2%, sequence, that, sars-cov-2"
27591,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.111111111,"sars-cov-2, from, to, coronaviruses, bat, bats"
27592,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.111111111,"and, bat, to, as, a, bats, that, in, which, can, is"
27593,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.111111111,"sequences, and, that, of, receptor, which, as"
27594,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.111111111,"the, of, that, to, suggested, this"
27595,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.111111111,"the, to, evidence, support, of, this"
27596,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.111111111,"as, et, al., the, of, this, to"
27597,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.111111111,"that, the, of, evidence, was, to"
27598,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.111111111,"et, al., that, the, to, may, this, hypothesis, of"
27599,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.111111111,"evidence, to, that, the, of, may, as"
27600,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.111111111,"the, to, is, be"
27601,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.111111111,"the, most, likely, candidate"
27602,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.111111111,"to, be, considered"
27603,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.111111111,"sars-cov-2, a, coronavirus, the"
27604,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.111111111,"after, of, to, the, that"
27605,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.111111111,"the, of, to, is, a, that"
27606,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.111111111,"that, in, a, to"
27607,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.111111111,"the, of, that, was, to"
27608,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.111111111,"with, the, was, in, of"
27609,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.111111111,"with, the, of, a, genome"
27610,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.111111111,"of, similar, a, in, the"
27611,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.111111111,"to, of, that, similar, in"
27612,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.111111111,"closely, related, to, and"
27613,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.111111111,"sars-cov-2., and, pangolin, to"
27614,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.111111111,"the, of, a"
27615,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.111111111,"a, the, of, be, that, host"
27616,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.111111111,"the, of, be"
27617,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.111111111,"be, a, that, the"
27618,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.111111111,"that, the, of, be"
27619,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.111111111,"be, a, the"
27620,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.111111111,"sars-cov-2, the, infected"
27621,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.111111111,"of, the, human, with"
27622,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.111111111,"the, are, with, of, sars-cov-2"
27623,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.111111111,"the, that, to, after, of"
27624,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.111111111,"the, that, of, cases, huanan, seafood"
27625,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.111111111,"to, that, the, of, be"
27626,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.111111111,"data, that, sars-cov-2, a"
27627,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.111111111,"the, huanan, market, to"
27628,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.111111111,"on, the, have, is, to"
27629,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.111111111,"in, is, at, the, on"
27630,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.111111111,"et, to, the, sars-cov-2, and"
27631,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.111111111,"cov, to, sars-cov-2"
27632,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.111111111,"sars-cov-2, the, of, to, from, closest"
27633,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.111111111,"the, was, a, bat, to"
27634,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.111111111,"from, an, to, a"
27635,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.111111111,"the, from, an, in, to"
27636,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.111111111,"sars-cov-2, was, from, to"
27637,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.111111111,"the, was, in"
27638,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.111111111,"the, was, bat, batcov"
27639,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.111111111,"in, the, was"
27640,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.111111111,"in, viruses, been"
27641,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.111111111,"have, in, bats, rhinolophus"
27642,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.111111111,"been, sars-cov-2, in"
27643,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.111111111,"have, been, sars-cov-2"
27644,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.111111111,"that, be, the, reservoir"
27645,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.111111111,"the, spillover, an"
27646,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.111111111,"that, the, at, of"
27647,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.111111111,"sars-cov-2, and, receptor, ace2, a"
27648,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.111111111,"a, of, and, that, the, in"
27649,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.111111111,"was, that, the, in, a, of"
27650,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.111111111,"the, in, and, on"
27651,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.111111111,"scientific, that, and, for"
27652,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.111111111,"and, a, of, in, the, for"
27653,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.111111111,"viruses, been, in"
27654,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.111111111,"the, of, natural, in"
27655,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.111111111,"the, in, for"
27656,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.111111111,"the, natural, sites, of"
27657,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.111111111,"sars-cov-2, natural, and, the"
27658,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.111111111,"as, the, of, a"
27659,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.111111111,"of, from, a, sars-cov-2"
27660,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.111111111,"the, sars-cov-2, which, to, of, found, in"
27661,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.111111111,"the, of, its, to, that, sars-cov-2"
27662,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.111111111,"was, that, the, sars-cov-2, to, which"
27663,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.111111111,"to, its, in, the, which, that"
27664,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.111111111,"the, that, virus, found, in, this"
27665,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.111111111,"of, sars-cov-2, but, that, the"
27666,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.111111111,"the, sars-cov-2, this, pangolin, of"
27667,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","this one jumped from bats origin  

into humans",0.111111111,"into, humans, from"
27668,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","this one jumped from bats origin  

into humans",0.111111111,"origin, jumped, humans"
27669,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.111111111,"than, the, to, was"
27670,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.111111111,"animals, to, the, was, transmitted"
27671,"Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.111111111,"the, we, leak"
27672,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.111111111,"laboratory, a, coronavirus"
27673,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.111111111,"the, to, we, was"
27674,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.111111111,"we, to, the"
27675,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.111111111,"the, coronavirus, to, than"
27676,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.111111111,"the, have, as, of, and, viruses"
27677,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.111111111,"of, the, viruses, have, a"
27678,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.111111111,"studies, the, of, these, and, covs"
27679,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.111111111,"coronaviruses, of, a, bats"
27680,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.111111111,"the, are, of, bats, china"
27681,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.111111111,"health, the, of, virus"
27682,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.111111111,"a, of, the, are, by, virus"
27683,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.111111111,"a, the, in, and"
27684,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.111111111,"the, bat, has"
27685,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.111111111,"the, been, in, and"
27686,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.111111111,"the, bat, in, and"
27687,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.111111111,"a, the, in, bat"
27688,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.111111111,"the, has, of, and"
27689,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.111111111,"to, that, bats, hosts, for"
27690,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.111111111,"related, to, covs, for, also"
27691,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.111111111,"bats, are, hosts, related, to, that, covs"
27692,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.111111111,"and, viruses, of, wild, the"
27693,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.111111111,"of, the, sars-cov-2, and, zoonotic, in, viruses"
27694,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.111111111,"of, sars-cov-2, the, wild, for"
27695,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.111111111,"bats, as, the, with, of, for, and"
27696,"Bats are natural hosts of many of the known  

coronaviruses","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.111111111,"bats, natural, of, the"
27697,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.111111111,"a, the, with, genome, of"
27698,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.111111111,"to, similarity, sars-cov-2, genome"
27699,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.111111111,"similarity, to, a, genome"
27700,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.111111111,"sars-cov-2, to, sars-cov"
27701,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.111111111,"sars-cov-2, genetic, with, a"
27702,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.111111111,"with, the, sars-cov-2, in"
27703,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.111111111,"with, a, the, in"
27704,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.111111111,"a, genetic, sars-cov-2, the"
27705,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.111111111,"sars-cov-2, the, for, in"
27706,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.111111111,"the, in, for, sars-cov-2"
27707,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.111111111,"shared, a, possible, in, the"
27708,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.111111111,"pangolins, in, with, sars-cov-2, the"
27709,"t some virus detected in pangolins 

were capable of infecting humans.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.111111111,"in, pangolins, were"
27710,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.111111111,"in, the, cov, a"
27711,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.111111111,"live, animal, markets, zoonotic, and, in, the, spillover, events, that, to"
27712,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.111111111,"the, of, a, may, to, spillover"
27713,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.111111111,"a, to, the, spillover"
27714,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.111111111,"of, to, a, bat, yunnan"
27715,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.111111111,"there, that, sars-cov-2, to, is, viruses"
27716,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.111111111,"the, of, institute, to, viruses, there, had, no"
27717,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.111111111,"to, is, similar, sars-cov-2, the"
27718,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.111111111,"the, that, of, sars-cov-2, is, or"
27719,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.111111111,"the, highly, was, to, any, and"
27720,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.111111111,"the, was, and, to, provide"
27721,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.111111111,"to, by, sars-cov-2, the, genome"
27722,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.111111111,"sars-cov-, 2, to, and"
27723,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.111111111,"provide, consistent, to, the, and, sars-cov-2"
27724,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.111111111,"provide, and, the, sars-cov-2"
27725,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.111111111,"the, in, is, to, sars-cov-2"
27726,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.111111111,"the, that, sars-cov-2, not"
27727,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.111111111,"that, the, in, to"
27728,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.111111111,"in, related, to, sars-cov-2, the"
27729,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.111111111,"related, to, in, sars-cov-2, the"
27730,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.111111111,"that, to, sars-cov-2, in"
27731,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.111111111,"sars-cov-2, in, is, the, to"
27732,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.111111111,"it, that, the, with, in, a, of"
27733,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.111111111,"the, that, sars-cov-2, and, not, a"
27734,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.111111111,"the, virus, to, with, human"
27735,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.111111111,"the, to, in, a, for, of, with, is, that, virus, and"
27736,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.111111111,"that, sars-cov-2, is, not, a"
27737,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.111111111,"to, the, of, a, virus, with"
27738,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.111111111,"sars-cov-2, of, the, and, with, to, in, virus"
27739,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.111111111,"that, a, the, of, sars-cov-2, is, to, an"
27740,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.111111111,"from, with, bats, to, the, of"
27741,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.111111111,"over, in, humans, is, that, the, sars-cov-2"
27742,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.111111111,"is, sars-cov-2, pangolin, to, the, that, in"
27743,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.111111111,"found, sars-cov-2, from, malayan, coron-, avirus, of"
27744,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.111111111,"with, the, of, and, which, from"
27745,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.111111111,"two, the, of, sars-cov-2, from"
27746,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.111111111,"in, the, rhinolophus, and"
27747,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.111111111,"the, of, which, with, sars-cov-2"
27748,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.111111111,"the, of, sequences, in, from"
27749,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.111111111,"similarity, sars-cov-2, with"
27750,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.111111111,"sars-cov-2, a, of, found, in, bat"
27751,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.111111111,"sars-cov-2, has, a, in"
27752,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.111111111,"that, a, virus, found, in"
27753,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.111111111,"that, in, virus, of"
27754,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.111111111,"the, that, later"
27755,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.111111111,"that, the, is"
27756,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.111111111,"to, from, with, the"
27757,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.111111111,"the, from, to"
27758,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.111111111,"the, been, of, host, zoonotic"
27759,The FCS of SARS-CoV-2 was not bioengineered—full stop.,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.111111111,"the, of, not"
27760,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.111111111,"that, has, the, origin"
27761,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.111111111,"the, host, of, animal"
27762,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.111111111,"the, of, that, and, sars-cov-2"
27763,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.111111111,"sars-cov-2, the, of, sequence"
27764,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.111111111,"the, pangolin-cov, same, sars-cov-2"
27765,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.111111111,"of, the, et, al."
27766,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.111111111,"has, sars-cov-2, the, of, in"
27767,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.111111111,"the, of, degree, in, ratg13, to"
27768,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.111111111,"of, region, in, sars-cov-2"
27769,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.111111111,"in, of, sars-cov-2, found, to"
27770,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.111111111,"found, in, has, the"
27771,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.111111111,"the, region, has, in, to, of"
27772,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.111111111,"sars-cov-2, et, and, to, the"
27773,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.111111111,"and, to, an, in, the"
27774,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","bats are also important reservoir species for a great 

range of coronaviruses",0.111111111,"also, a, of, species, for"
27775,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.111111111,"bats, and, the, of, species"
27776,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.111111111,"the, in, humans, from"
27777,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.111111111,"the, in, to, from, humans"
27778,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.111111111,"an, to, from, in, the, were, of, several, and, species"
27779,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.111111111,"in, and, to, humans"
27780,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.111111111,"several, species, of, the"
27781,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.111111111,"sars-cov-2, the, and, an"
27782,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.111111111,"the, with, and, two"
27783,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.111111111,"from, with, the, sequence, s"
27784,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.111111111,"nucleotide, and, from, bat"
27785,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.111111111,"sars-cov-2, the, with, ratg13, which"
27786,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.111111111,"the, of, sars-cov-2, with, ratg13"
27787,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.111111111,"the, of, at, sars-cov-2, has"
27788,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.111111111,"sars-cov-2, at, the, sequence, with"
27789,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.111111111,"the, is, to, one, and"
27790,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.111111111,"the, horseshoe, bats, most, to, and"
27791,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.111111111,"the, most, to, sars-cov-2,, by, is"
27792,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.111111111,"to, found, in, bats, and, from"
27793,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.111111111,"bats, and, found, in, by, the"
27794,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.111111111,"human, can, to, in"
27795,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.111111111,"a, to, for, the"
27796,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.111111111,"in, the, s, protein, a, for"
27797,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.111111111,"to, in, the, protein, for, ace2"
27798,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.111111111,"the, pangolin-cov, sars-cov-2, same"
27799,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.111111111,"that, the, of, as, sars-cov-2, et, al.,, and"
27800,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.111111111,"that, the, of, sars-cov-2, and, as, et, al.,"
27801,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.111111111,"that, the, rbd, of, affinity, to"
27802,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.111111111,"and, to, be, that, the, of, is, natural, sars-cov-2"
27803,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.111111111,"the, sars-cov-2, animal, that, in, and"
27804,"bats are also important reservoir species for a great 

range of coronaviruses","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.111111111,"also, species, for, a, of"
27805,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.111111111,"that, or, the, hosts, for, sars-cov-2"
27806,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.111111111,"the, and, also, a, in, ace2, that, of"
27807,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.111111111,"the, sars-cov-2, than, that, in, and"
27808,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.111111111,"the, to, that, in, and, humans"
27809,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.111111111,"amino, the, rbd, be, to, sars-cov-2"
27810,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.111111111,"for, the, and, intermediate, that, in, humans, with, to"
27811,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.111111111,"sars-cov-2, the, rbd, and, in, that, based"
27812,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.111111111,"intermediate, and, to, for, the, that, sars-cov-2, may, in"
27813,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.111111111,"have, been, and, in, to, the, has"
27814,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.111111111,"and, sars-cov-2, to, in, a"
27815,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.111111111,"changes, and, that, the, was"
27816,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.111111111,"the, sars-cov-2, to, a, in"
27817,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.111111111,"that, the, in, infect, a, to"
27818,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.111111111,"that, and, sars-cov-2, a, common"
27819,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.111111111,"the, that, sars-cov-2, to, a"
27820,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.111111111,"be, sars-cov-2, to, the, amino, rbd"
27821,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.111111111,"to, the, sars-cov-2, of, humans"
27822,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.111111111,"the, of, is, to, for, be"
27823,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.111111111,"to, and, of, it, is, possible"
27824,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.111111111,"the, from, a, to"
27825,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.111111111,"the, to, as, intermediate"
27826,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.111111111,"to, an, intermediate"
27827,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.111111111,"an, intermediate, host, the"
27828,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.111111111,"the, of, that, evidence, was, to"
27829,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.111111111,"to, and, was, provide, the"
27830,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.111111111,"to, the, and, provide, evidence, that"
27831,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.111111111,"the, human, in, market, to"
27832,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.111111111,"the, covid-19, approximately, to, of"
27833,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.111111111,"cases, associated, with, the, huanan, of, to, were, covid-19, in, market"
27834,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.111111111,"were, to, of, in, the, huanan"
27835,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.111111111,"sars-cov-2, to, and"
27836,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.111111111,"in, the, of, intermediate"
27837,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.111111111,"at, the, was, in, from"
27838,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.111111111,"that, from, was, the, intermediate"
27839,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.111111111,"the, sequences, of, from, in"
27840,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.111111111,"at, this, in, the, that"
27841,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.111111111,"in, bat, to"
27842,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.111111111,"in, nature, with"
27843,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.111111111,"in, to, sars-cov-2"
27844,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.111111111,"in, with, banal, to, sars-cov-2"
27845,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.111111111,"to, in, with, sars-cov-2, bat"
27846,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan",0.111111111,"animal, of, dogs"
27847,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan",0.111111111,"live, animal, markets, in"
27848,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.111111111,"for, the, of, market, samples, that"
27849,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.111111111,"samples, that, from, the"
27850,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.111111111,"the, of, for, sars-cov-2"
27851,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.111111111,"of, the, sars-cov-2, in, from"
27852,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.111111111,"the, result, of, sars-cov-2, to, a, in"
27853,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.111111111,"that, the, of, in, recombination, events, a, to"
27854,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.111111111,"a, and, in, the, events, that, to"
27855,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.111111111,"has, been, with, that, and, sars-cov-2, a"
27856,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.111111111,"the, of, that, sars-cov-2, to, a, with"
27857,COVID-19 is a zoonotic virus,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.111111111,"covid-19, is, a, virus"
27858,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.111111111,"the, genome, that, sars-cov-2, from, a"
27859,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.111111111,"a, of, sars-cov-2, genome, at, the"
27860,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.111111111,"that, sars-cov-2, the, at, of, virus"
27861,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.111111111,"the, virus, covid-19, a, of, to"
27862,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.111111111,"a, the, to, in, sars-cov-2"
27863,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.111111111,"to, sars-cov-2, result, a, of, in, the"
27864,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.111111111,"of, the, covid-19, is, a, or"
27865,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.111111111,"a, of, virus, to, the, sars-cov-2"
27866,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.111111111,"of, the, in, sars-cov-2, a"
27867,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.111111111,"sars-cov-2, to, a, the, of"
27868,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.111111111,"the, most, in, bats"
27869,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.111111111,"bats, in, the, southeast"
27870,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.111111111,"are, the, in, and, bats, or"
27871,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",Coronaviruses account for over 30% of the world’s viruses.,0.111111111,"over, the, of, coronaviruses"
27872,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.111111111,"bats, for, as, the, of, and"
27873,"insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.111111111,"of, as, and"
27874,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.111111111,"bats, and, the, as"
27875,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.111111111,"animal, and, the, sars"
27876,Bats are hosts of many coronaviruses,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.111111111,"bats, of"
27877,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.111111111,"the, viruses, as"
27878,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.111111111,"the, of, animal, for"
27879,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.111111111,"the, and, horseshoe, bats, most, to"
27880,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.111111111,"the, intermediate, as, to"
27881,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.111111111,"the, to, of, as, reservoir, horseshoe, most, likely, bats, and"
27882,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.111111111,"intermediate, species, bats, and, the"
27883,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.111111111,"are, that, sars-cov-2, to, and, in"
27884,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.111111111,"the, that, to, are, closely, related, most, in, and, sars-cov-2"
27885,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.111111111,"all, to, in, and"
27886,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.111111111,"the, to, sars-cov-2, in, bat"
27887,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.111111111,"the, and, in, bat"
27888,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.111111111,"to, that, the, and, are, sars-cov-2"
27889,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.111111111,"the, were, to, and"
27890,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.111111111,"the, virus, for, to, and"
27891,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.111111111,"in, to, the, virus, and"
27892,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.111111111,"and, in, were, china"
27893,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.111111111,"the, in, to, virus"
27894,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.111111111,"virus, to, and, the, for"
27895,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.111111111,"the, in, and, viruses"
27896,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.111111111,"the, of, and, an, to"
27897,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.111111111,"and, of, to, an, species"
27898,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.111111111,"in, to, the, and, an"
27899,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.111111111,"to, the, in, of, and, role"
27900,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.111111111,"of, to, the, in"
27901,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.111111111,"to, and, of, in, bat"
27902,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.111111111,"and, viruses, of, within, this, the"
27903,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.111111111,"of, and, species, are, the"
27904,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.111111111,"a, in, the, similar, of"
27905,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.111111111,"a, possible, shared, the, in"
27906,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.111111111,"the, by, bat, species, in"
27907,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.111111111,"this, bat, within, the, same, are"
27908,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.111111111,"the, covid-19, a, of, to, that, bat"
27909,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.111111111,"in, but, to, of, the, covid-19, genetic"
27910,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.111111111,"a, that, the, to, infect, in"
27911,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.111111111,"to, a, recombination, of, in, the, that, events"
27912,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.111111111,"the, in, of, to, that, can"
27913,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.111111111,"of, the, in, that, a, viruses"
27914,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.111111111,"is, a, and, bat, can, as, to, which, that, in, bats"
27915,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.111111111,"a, of, viruses, in, and, to, which, the, new"
27916,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.111111111,"of, the, bat, and, are, into, clusters, cluster, with, other, as, viruses"
27917,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.111111111,"in, this, can, that, the, recombination, and, of, bat"
27918,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.111111111,"from, of, a, sars-cov-2, have, to"
27919,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.111111111,"closest, to, sars-cov-2,, which, sars-cov-2"
27920,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.111111111,"from, all, sars-cov-2, to, a"
27921,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.111111111,"of, to, a, which, from"
27922,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.111111111,"of, sars-cov-2, with, to"
27923,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.111111111,"is, the, closest, to, similarity"
27924,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.111111111,"the, coronavirus, bat, sars-cov-2"
27925,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.111111111,"sars-cov-2, similarity, genome, to"
27926,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.111111111,"is, the, similar, to, sars-cov-2"
27927,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.111111111,"to, by, genome, the, sars-cov-2"
27928,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.111111111,"the, to, related, sars-cov-2, bat"
27929,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.111111111,"the, related, to, which, is"
27930,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.111111111,"similar, to, and, with, the, sars-cov-2"
27931,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.111111111,"the, similar, to, and, in"
27932,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.111111111,"the, in, related, to, sars-cov-2"
27933,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.111111111,"banal, with, to, sars-cov-2, in"
27934,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.111111111,"the, banal, closely, related, to, by"
27935,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.111111111,"and, a, sars-cov-2, in, which, the, to"
27936,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.111111111,"sars-cov-2, the, with, at, and, to"
27937,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.111111111,"sars-cov-2, the, and, with, similar, to, sars-, in"
27938,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.111111111,"the, sars-cov-2, also, to, by"
27939,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.111111111,"the, similarity, sars-cov-2, of, to"
27940,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.111111111,"the, sars-cov-2, their, of"
27941,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.111111111,"of, and, similar, to, sars-cov-2."
27942,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.111111111,"closely, related, to, a, the, is, same, location"
27943,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",all three BANAL series viruses also use ACE2 as an entry receptor.,0.111111111,"banal, series, viruses"
27944,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.111111111,"with, the, to, of"
27945,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.111111111,"of, to, that, the"
27946,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.111111111,"through, have, that, the, to"
27947,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.111111111,"human, ace2, with, the, of"
27948,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.111111111,"of, the, with, that"
27949,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.111111111,"the, affinity, of, rbd, to, that"
27950,"zoonotic corona- 

viruses have become an increasing threat to human health,","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.111111111,"have, to, human"
27951,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.111111111,"shown, to, than"
27952,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.111111111,"to, the, of, sars-cov-2."
27953,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","This suggests that the BANAL series may be able to directly infect  

humans.",0.111111111,"the, that, to, this"
27954,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","This suggests that the BANAL series may be able to directly infect  

humans.",0.111111111,"the, to, this, be"
27955,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","This suggests that the BANAL series may be able to directly infect  

humans.",0.111111111,"the, suggests, that, may, to"
27956,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","This suggests that the BANAL series may be able to directly infect  

humans.",0.111111111,"banal, series, the"
27957,"This suggests that the BANAL series may be able to directly infect  

humans.","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.111111111,"the, banal, series"
27958,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.111111111,"the, of, more, in"
27959,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.111111111,"the, from, is, also"
27960,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.111111111,"is, the, in, spike, from"
27961,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.111111111,"of, a, at, the"
27962,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.111111111,"have, the, of, a, viruses"
27963,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.111111111,"their, the, of, a"
27964,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.111111111,"the, location, closely, related, is, a, to, same"
27965,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.111111111,"a, at, the, is, closely, related, to"
27966,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.111111111,"the, amino, acid, of"
27967,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.111111111,"sars-cov-2, the, amino, acid, of"
27968,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.111111111,"the, is, most, to, sars-cov-2,, by"
27969,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.111111111,"by, closely, related, banal, to, the"
27970,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.111111111,"closely, related, to, ratg-13., the, bat"
27971,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.111111111,"to, the, of, by, virus"
27972,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.111111111,"t, and, bats"
27973,"Scientific reports published so far include  

hosts, such as bats (28), pangolins (29), cats  

(11), and dogs (30)","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.111111111,"as, bats, and"
27974,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.111111111,"the, virus, in, to"
27975,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.111111111,"the, covid-19, virus, to"
27976,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.111111111,"virus, the, sars-cov-2, in"
27977,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.111111111,"the, sars-cov-2, virus, to"
27978,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.111111111,"the, of, similar, is"
27979,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.111111111,"genomic, sars-cov-2, related, to, bat, the"
27980,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.111111111,"the, closely, related, to, bat, ratg-13."
27981,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.111111111,"are, the, more, sars-cov-2, than"
27982,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.111111111,"due, to, recombination, the, a, with"
27983,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.111111111,"sars-cov-2, the, recent, and, with, to, in, rmyn02,"
27984,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.111111111,"the, that, in, and, humans"
27985,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.111111111,"that, humans, is, in, sars-cov-2, over, the"
27986,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.111111111,"sars-cov-2, the, and, in, that, is"
27987,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.111111111,"is, the, that, identified, and, be"
27988,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.111111111,"a, collected, and, were, 19, of, the, huanan"
27989,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.111111111,"the, was, to, at, with, of, and"
27990,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.111111111,"the, of, from, with, a, and"
27991,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.111111111,"a, the, to, that, discovered, in, had, human, virus, was"
27992,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.111111111,"the, virus, have, into, human, an, animal, in, or, to"
27993,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.111111111,"the, of, that, to, wet, animal, market, in"
27994,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.111111111,"a, for, the, palm, civet, positive, of, wild, with"
27995,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.111111111,"the, of, sars, in, closely, related, to"
27996,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.111111111,"this, of, to, the, in, that, virus, or"
27997,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.111111111,"evidence, that, the, virus, as, of, a"
27998,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.111111111,"that, and, intermediate, for, to, humans, the, in, with"
27999,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.111111111,"evidence, in, the, and, that, of, positive, samples, collected, were, to, taken, from, located, market"
28000,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.111111111,"a, was, confirmed, that, the, and, to, host"
28001,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.111111111,"and, a, to, the, of, human, palm, as, intermediate"
28002,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.111111111,"a, and, was, in, an, host, humans"
28003,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.111111111,"from, a, identical, to, in, the, that, human"
28004,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.111111111,"a, of, the, from, this, and, at, two, in, which, viruses, were, circulating"
28005,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.111111111,"a, study, by, genome, from, in, that, the, to, group, of, were, found, present"
28006,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.111111111,"in, an, from, species, of, were, to, and, the, several"
28007,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.111111111,"chinese, for, and, an, from, to, at, the, in, of, collected, a, tested, animal"
28008,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.111111111,"that, the, a, market, live, animals, in, to, and, spread"
28009,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.111111111,"the, horseshoe, bats, most, likely, to, as, reservoir, of, and"
28010,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.111111111,"at, an, to, a, from, animal, in, chinese, tested, for, the, collected, of, and"
28011,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.111111111,"a, for, the, of, is, and, in, with, that, to, an"
28012,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.111111111,"the, with, wuhan, in, market, were, a, of"
28013,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.111111111,"of, the, covid-19, cases, in, to, were, associated, with, huanan, market"
28014,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.111111111,"in, and, all, sars-cov-2, with, this, that, the, difference, between, sars, is, than"
28015,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.111111111,"on, the, of, were, to, in"
28016,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.111111111,"of, the, in, to, were, huanan"
28017,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.111111111,"collected, a, of, the, 19, were, and, huanan"
28018,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.111111111,"of, shows, to, a, which, in"
28019,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.111111111,"the, of, and, cases, huanan, market"
28020,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.111111111,"the, covid-19, a, of, to, and"
28021,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.111111111,"to, is, of, the, covid-19, and"
28022,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.111111111,"huanan, seafood, the, and, of"
28023,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.111111111,"a, of, one, to, and, the"
28024,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.111111111,"is, the, known, to, of"
28025,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.111111111,"the, animal, and, that, at, in"
28026,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.111111111,"that, and, in, at, a"
28027,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.111111111,"and, the, to, markets, live, animal, in, that, spillover, events, zoonotic"
28028,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.111111111,"the, in, that, this, at"
28029,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.111111111,"to, a, in, the, and, that, events"
28030,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.111111111,"the, animal, sars, and"
28031,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.111111111,"the, in, to, that, this"
28032,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.111111111,"that, a, to, and, are, the"
28033,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.111111111,"this, the, in, that, are"
28034,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.111111111,"are, at, that, the, of, lineage"
28035,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.111111111,"huanan, seafood, in, the, and, of"
28036,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.111111111,"with, and, also, fall, the"
28037,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.111111111,"of, cases, the, huanan, seafood, that"
28038,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.111111111,"and, human, that, of, the, is"
28039,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.111111111,"that, of, with, one, and, are, the"
28040,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.111111111,"sars-cov-2, be, a, spillover, of, and, the"
28041,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.111111111,"of, the, market, and, were, in, to, samples, evidence, that, taken, from, positive, collected, located"
28042,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.111111111,"a, to, the, virus, that, is, for, found"
28043,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.111111111,"a, the, on, found, virus, that, is, most"
28044,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.111111111,"its, the, virus, to, a"
28045,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.111111111,"the, through, to, that, most"
28046,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.111111111,"its, into, to, for, the, that, sars-cov-2, a"
28047,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.111111111,"a, that, the, virus, is, to, found"
28048,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Those who eagerly peddle suggestions of 

laboratory involvement have consistently failed to present 

credible arguments to support their positions.",0.111111111,"arguments, have, their, to, of"
28049,"ARS-CoV-2 is a 

natural virus, not a lab-created one.","expended to make the simple point 

that COVID-19 had a natural origin.",0.111111111,"a, natural"
28050,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.111111111,"and, that, from, in, bats, pangolins"
28051,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.111111111,"in, coronaviruses, to, and"
28052,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.111111111,"pangolins, to, from, and, sars-cov-2"
28053,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.111111111,"to, and, that, in"
28054,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.111111111,"that, sars-cov-2, related, to, bats"
28055,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.111111111,"that, from, in, to, and"
28056,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.111111111,"and, in, found, bats, from, to"
28057,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.111111111,"related, coronaviruses, to, in, sars-cov-2, and"
28058,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.111111111,"bats, and, found, in, related"
28059,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.111111111,"that, sars-cov-2, and, from, bats"
28060,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.111111111,"we, the, leak"
28061,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.",0.111111111,"the, host, and"
28062,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.",0.111111111,"and, the, zoonotic"
28063,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.111111111,"results, and, natural, of"
28064,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.111111111,"to, a, and, in"
28065,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.111111111,"results, of, the, to"
28066,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.111111111,"and, the, of, to, viruses, a, new, in, which"
28067,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.111111111,"origin, humans, and, animal, sars-cov-2"
28068,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.111111111,"a, was, sars-cov-2, and, host"
28069,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.111111111,"a, in, has, sars-cov-2"
28070,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.111111111,"in, an, host, was, a, humans, and"
28071,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.111111111,"a, host, sars-cov-2, or"
28072,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.111111111,"a, zoonotic, origin, and"
28073,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.111111111,"samples, in, the, that, a, sars-cov-2"
28074,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.111111111,"a, the, bat, sequence, identity, with"
28075,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.111111111,"the, a, in, bat"
28076,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.111111111,"the, virus, sars-cov-2, in"
28077,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.111111111,"the, that, sars-cov-2, a, bat"
28078,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.111111111,"is, not, that, sars-cov-2, a"
28079,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.111111111,"to, sars-cov-2, is, a, that, the"
28080,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.111111111,"the, is, that, to, a, of"
28081,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.111111111,"sars-cov-2, is, to, likely, the, or"
28082,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.111111111,"the, natural, is, not, to, of"
28083,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.111111111,"natural, of, the, spike, a, to, that"
28084,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.111111111,"coronavirus, a, laboratory"
28085,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.111111111,"is, that, of"
28086,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.111111111,"of, sars-cov-2, is"
28087,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.111111111,"of, genetic, available, the"
28088,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.111111111,"have, the, for, of"
28089,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.111111111,"is, the, that, virus"
28090,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.111111111,"the, that, not, from"
28091,"zoonotic corona- 

viruses have become an increasing threat to human health,","atural  

selection in an animal host before zoonotic  

transfer;",0.111111111,"zoonotic, an"
28092,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.111111111,"the, to, bats, of, is"
28093,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.111111111,"the, of, that, likely, hosts, for"
28094,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.111111111,"bats, to, that, hosts, for"
28095,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.111111111,"for, to, the, of"
28096,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.111111111,"is, the, similarity, for"
28097,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.111111111,"the, that, is, identical, to"
28098,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.111111111,"that, in, the, it, not"
28099,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.111111111,"its, in, the, which, that, to"
28100,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.111111111,"in, the, a, that, from, identical, to, human"
28101,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.111111111,"sars-cov-2, the, of, that, to, coronaviruses, including"
28102,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.111111111,"is, the, to, that, in, similarity"
28103,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.111111111,"sars-cov-2, that, is, in, this"
28104,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.111111111,"to, in, the, protein, ace2, for"
28105,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.111111111,"is, the, in, binding, spike, protein, pangolin"
28106,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.111111111,"the, binding, to, in, sars-cov-2"
28107,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.111111111,"the, rbd, of, to, that, sars-cov-2"
28108,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.111111111,"the, of, and, can"
28109,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.111111111,"the, which, that, of, and"
28110,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.111111111,"that, natural, the, of, and"
28111,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.111111111,"it, that, the, of"
28112,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.111111111,"in, the, of, pangolins"
28113,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.111111111,"t, the, to, was, in"
28114,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.111111111,"the, of, that, was, very, to"
28115,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.111111111,"we, the, was, to"
28116,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.111111111,"that, the, of, in, can, to"
28117,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.111111111,"this, in, the, that, to"
28118,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.111111111,"sars-cov-2, to, very, in, the"
28119,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.111111111,"sars-cov-2, virus, the, an"
28120,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.111111111,"with, the, and, sars-cov-2, of"
28121,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.111111111,"the, sars-cov-2, a, of, from"
28122,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.111111111,"the, from, a, and, of, with"
28123,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.111111111,"from, pangolins, with, sars-cov-2, the, of"
28124,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.111111111,"sars-cov-2, and, coronaviruses, the, of"
28125,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.111111111,"that, the, of, sars-cov-2, and, is, we"
28126,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.111111111,"is, all, that, the, of"
28127,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.111111111,"that, and, sars-cov-2, based, the, in, rbd"
28128,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","In the 

case of MERS, dromedaries were the principal host.",0.111111111,"of, in, the"
28129,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.111111111,"been, to, from, through, in, is"
28130,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.111111111,"and, have, trans-, from, or, in"
28131,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.111111111,"the, to, that, was, not"
28132,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.111111111,"a, of, coronavirus, the"
28133,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.111111111,"genome, the, of, covid-19"
28134,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.111111111,"of, the, a, their"
28135,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.111111111,"that, in, the, virus, however,"
28136,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.111111111,"this, found, in, the, that, virus"
28137,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.111111111,"this, that, in, the, virus"
28138,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.111111111,"indicated, that, the, of, and, to"
28139,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.111111111,"to, based, on, the, in, that"
28140,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.111111111,"the, to, bats, in, of"
28141,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.111111111,"the, sars-cov, of, and, sequence, identity"
28142,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.111111111,"more, in, the, of"
28143,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.111111111,"to, the, from, bats,"
28144,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.111111111,"indicates, that, the, to, and"
28145,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.111111111,"from, to, the, covid-19"
28146,"An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",The COVID-19 most likely developed from bat origin coronaviruses,0.111111111,"coronaviruses, bat"
28147,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",The COVID-19 most likely developed from bat origin coronaviruses,0.111111111,"the, likely, covid-19"
28148,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",The COVID-19 most likely developed from bat origin coronaviruses,0.111111111,"bat, coronaviruses, the"
28149,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.111111111,"from, animal, a, as, high, bat, species"
28150,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.111111111,"these, that, from, the, bat, of"
28151,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.111111111,"evidence, the, that, a, as, from"
28152,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.111111111,"the, covid-19, is, of, or, a"
28153,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.111111111,"that, the, of, origin, evidence, is"
28154,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.111111111,"that, the, is, a, or"
28155,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.111111111,"of, the, sequence, that"
28156,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.111111111,"the, of, amino, acid"
28157,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.111111111,"of, and, that, the, in, bats"
28158,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.111111111,"to, humans, and, the, of"
28159,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.111111111,"that, the, wuhan, in, seafood, of"
28160,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.111111111,"that, bats, and, hosts"
28161,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.111111111,"of, the, and, to, in, virus, analysis"
28162,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.111111111,"in, are, and"
28163,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.111111111,"in, to, and, humans"
28164,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.111111111,"be, are, animals, in"
28165,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.111111111,"are, all, that, to"
28166,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.111111111,"are, be, to"
28167,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.111111111,"to, be, that, originated"
28168,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.111111111,"are, in, that, to"
28169,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",Bats are hosts of many coronaviruses,0.111111111,"of, many, coronaviruses"
28170,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.111111111,"viruses, in, animal"
28171,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.111111111,"to, in, animal"
28172,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.111111111,"an, intermediate, to"
28173,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.111111111,"an, intermediate, humans, in"
28174,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.111111111,"to, the, market, in"
28175,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.111111111,"the, covid-19, is"
28176,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.111111111,"in, the, is, to"
28177,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.111111111,"the, was, that, in"
28178,"All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.111111111,"the, that, in, chinese"
28179,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.111111111,"been, that, in"
28180,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.111111111,"the, later, that"
28181,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.111111111,"by, was, in, that, the, of"
28182,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.111111111,"which, was, in, the"
28183,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.111111111,"the, most, of, coronaviruses,, and"
28184,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.111111111,"the, bat, of, virus, and"
28185,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.111111111,"to, a, and, in, wuhan,, china"
28186,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.111111111,"and, to, role, in, the, of"
28187,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.111111111,"the, two, are, viruses, in, bats"
28188,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.111111111,"that, bats, are, the, reservoir, for"
28189,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.111111111,"they, in, animals, the, virus, which"
28190,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.111111111,"results, the, in, that, with"
28191,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.111111111,"with, the, to, in, of"
28192,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.111111111,"the, animals, that, to, of"
28193,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.111111111,"this, with, of, the, in"
28194,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.111111111,"the, first, to, that, was"
28195,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.111111111,"of, to, has, that, the"
28196,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.111111111,"the, of, have, that, was, to"
28197,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.111111111,"this, with, the, was, in, of"
28198,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.111111111,"have, a, as, studies, in, china"
28199,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.111111111,"studies, these, have, the, of"
28200,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.111111111,"have, in, rhinolophus, bats"
28201,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.111111111,"species, of, the, several"
28202,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.111111111,"that, several, species"
28203,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.111111111,"the, viruses,, sars-, cov-2"
28204,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.111111111,"is, lineage, the, in"
28205,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.111111111,"by, bat, species, in, the"
28206,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.111111111,"isolated, from, in, is, the"
28207,"preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.111111111,"some, transmission, of, viruses, during"
28208,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.111111111,"in, bats,, and, to, other"
28209,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.111111111,"to, is, the, bats, and"
28210,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.111111111,"and, the, is, scenario"
28211,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.111111111,"the, and, in, found, bats, by"
28212,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.111111111,"the, bats, species, intermediate, and"
28213,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.111111111,"related, found, in, bats, and"
28214,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.111111111,"in, humans, an, intermediate"
28215,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.111111111,"bats, are, they, as, of, and, more"
28216,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.111111111,"to, be, a, of, and, transmission"
28217,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.111111111,"virus, and, bats, be, of, to"
28218,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.111111111,"from, bats, to, be, of, virus"
28219,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.111111111,"are, in, or, bats"
28220,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.111111111,"the, sars-cov, was, in, animals, markets, china"
28221,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.111111111,"in, the, of, a, was, and, market"
28222,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.111111111,"of, in, the, market"
28223,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.111111111,"in, of, the, and, was"
28224,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.111111111,"in, of, and, the"
28225,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.111111111,"and, the, of, a"
28226,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.111111111,"the, in, of, was"
28227,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.111111111,"the, of, a, in, and, market, was"
28228,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.111111111,"and, a, of, the"
28229,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.111111111,"and, a, the, of"
28230,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.111111111,"the, sars-cov-2, of, from, origin"
28231,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.111111111,"the, of, and, have, sars-cov-2, is"
28232,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.111111111,"of, the, sars-cov-2, and, two"
28233,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.111111111,"of, sars-cov-2, and, from, their"
28234,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.111111111,"he, sequence, with, the, of, viral, sars-cov-2"
28235,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.111111111,"is, at, the, in, on"
28236,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.111111111,"pangolins, sars-cov-2, with, the, in"
28237,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.111111111,"s, from, the, sequence, with"
28238,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.111111111,"the, of, from, pangolins, with, sars-cov-2"
28239,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","t some virus detected in pangolins 

were capable of infecting humans.",0.111111111,"pangolins, were, in"
28240,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.111111111,"in, march, a, of, to, the, we, virus, that, from, were, live, as, positive"
28241,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.111111111,"a, by, et, al., from, at, in, that, the, virus, to, of, were"
28242,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.111111111,"the, bats, in, southeast"
28243,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.111111111,"bats, the, southeast, in"
28244,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.111111111,"the, bats, in, china"
28245,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.111111111,"bats, may, the, and"
28246,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.111111111,"the, and, or, may, intermediate, (or"
28247,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.111111111,"trans-, and, from, in, have, or"
28248,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.111111111,"from, in, an, intermediate, wildlife"
28249,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.111111111,"the, in, and, bats, or, pangolins"
28250,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.",0.111111111,"some, of, during, transmission, viruses"
28251,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.111111111,"a, the, of, and, animals, that, is"
28252,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.111111111,"the, of, covid-19, that"
28253,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.111111111,"the, that, animals, and"
28254,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.111111111,"of, the, covid-19, and"
28255,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.111111111,"is, the, that, and, this"
28256,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.111111111,"the, to, is, likely, covid-19"
28257,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.111111111,"the, a, from, animals, to, for"
28258,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.111111111,"from, also, the, a, animals, to"
28259,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.111111111,"the, a, from, most, likely, for"
28260,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.111111111,"also, to, covs, related, for"
28261,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.111111111,"related, to, is, which, the"
28262,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.111111111,"the, from, to, a, also"
28263,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.111111111,"to, a, of, and, the, ability"
28264,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.111111111,"a, that, common, and, sars-cov-2"
28265,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.111111111,"sars-cov-2, a, and, has, been, that, with"
28266,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.111111111,"that, sars-cov-2, and, bat, cov"
28267,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.111111111,"the, a, coronavirus, has, with, and, to"
28268,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.111111111,"the, and, in, bats, is"
28269,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.111111111,"bats, and, in, the"
28270,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.111111111,"the, virus, a, that"
28271,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.111111111,"a, of, virus, the"
28272,"atural  

selection in an animal host before zoonotic  

transfer;","zoonotic corona- 

viruses have become an increasing threat to human health,",0.111111111,"an, zoonotic"
28273,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.111111111,"virus, to, zoonotic"
28274,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.111111111,"of, virus, the, health"
28275,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.111111111,"the, of, to, for"
28276,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.111111111,"of, natural, origin, a"
28277,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.111111111,"based, on, comparative, genomic"
28278,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.111111111,"of, more, sars-, cov-2"
28279,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.111111111,"the, virus, a, that, has, to"
28280,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.111111111,"the, virus, have, been, or, to"
28281,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","ARS-CoV-2 is a 

natural virus, not a lab-created one.",0.111111111,"not, is, a"
28282,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.111111111,"in, the, with, by"
28283,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.111111111,"that, sars-cov-2, in, bat"
28284,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.111111111,"from, in, that, a, sars-cov-2, to"
28285,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.111111111,"an, intermediate, from, in, wildlife"
28286,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.111111111,"to, a, from, bat, in"
28287,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.111111111,"sars-cov-2, a, host, or"
28288,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.111111111,"the, infectious, of, humans"
28289,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.111111111,"is, that, the, of, or"
28290,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.111111111,"studies, that, in, to, humans"
28291,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.111111111,"that, in, to, sars-cov-2"
28292,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.111111111,"the, of, that, sars-cov-2, but"
28293,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.111111111,"the, has, been, a, of, that"
28294,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.111111111,"the, have, been, and"
28295,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.111111111,"been, the, in, of, as, and, had, before"
28296,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.111111111,"sars-cov-2, to, a, of, and, adapted, the"
28297,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.111111111,"this, of, to, the, in, that, had, been"
28298,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.111111111,"that, and, may, intermediate, for, sars-cov-2, to, the, in"
28299,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.111111111,"sars-cov-2, a, that, its, into, to, the, for"
28300,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.111111111,"not, the, was"
28301,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.111111111,"sars-cov-2, the, not, of"
28302,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.111111111,"the, more, previous, animal, for"
28303,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.111111111,"more, likely, transmission, an, animal"
28304,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.111111111,"the, more, likely, for"
28305,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.111111111,"sars-cov-2, been, in"
28306,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.111111111,"that, sars-cov-2, has"
28307,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.111111111,"in, that, animal"
28308,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.111111111,"sars-cov-2, found, to, the"
28309,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.111111111,"bat, genome, sars-cov-2"
28310,"�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.111111111,"cov, bat, the"
28311,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.111111111,"human, and, a, viral, genetic"
28312,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.111111111,"the, and, of, that, human"
28313,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.111111111,"a, the, of, is, virus, and, that"
28314,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.111111111,"that, and, the, of, most"
28315,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.111111111,"and, suggest, that, the, of"
28316,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.111111111,"the, is, that, of, human, and"
28317,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.111111111,"is, and, the, scenario"
28318,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.111111111,"the, of, that, likely, a"
28319,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.111111111,"the, natural, is, and, of"
28320,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",Genetic evidence suggesting otherwise is yet to be presented.,0.111111111,"is, evidence, to"
28321,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.111111111,"that, the, of, sars-cov-2, is, it"
28322,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.111111111,"is, that, the, of, sars-cov-2, or"
28323,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.111111111,"the, of, and, present"
28324,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.111111111,"to, the, sars-cov-2, is, origin"
28325,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.111111111,"the, of, sars-cov-2, and, evidence, is, to"
28326,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.111111111,"is, no, evidence, the, of"
28327,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.111111111,"has, been, in, the, and, to, have"
28328,"Those who eagerly peddle suggestions of 

laboratory involvement have consistently failed to present 

credible arguments to support their positions.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.111111111,"of, have, to, arguments, their"
28329,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.111111111,"is, sars-cov-2, and, to, the, in"
28330,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.111111111,"the, protein, is, in, bat"
28331,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.111111111,"pangolin, in, the, spike, protein, binding, is"
28332,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.111111111,"a, ratg13,, which, from, bat, in"
28333,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.111111111,"has, nucleotide, could, and"
28334,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.111111111,"could, an, to, and"
28335,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.111111111,"and, has, identity, to"
28336,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.111111111,"considered, to, be"
28337,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.111111111,"to, sars-cov-, 2, and"
28338,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.111111111,"to, ratg13, and"
28339,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",SARS-CoV-2 was created from SARS-CoV-2,0.111111111,"sars-cov-2, from, was"
28340,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.111111111,"and, from, to"
28341,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.111111111,"to, sars-cov-2, was, from"
28342,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.111111111,"that, was, and, to"
28343,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.111111111,"to, sars-cov-2, and"
28344,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.111111111,"viruses, are, and, sars-cov-2, ratg13, that"
28345,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.111111111,"to, that, and, are, sars-cov-2"
28346,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.111111111,"and, that, sars-cov-2"
28347,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.111111111,"sars-cov-2, with, genome, bat"
28348,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.111111111,"with, coronaviruses,, sars-cov-2"
28349,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.111111111,"genome, sars-cov-2, with, of, bat"
28350,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.111111111,"sars-cov-2, genome, bat"
28351,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.111111111,"viruses, that, the, from"
28352,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.111111111,"as, the, viruses"
28353,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.111111111,"evidence, that, the, from, as"
28354,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.111111111,"that, be, from"
28355,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.111111111,"to, the, from, is, origin"
28356,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.111111111,"that, the, and, is, but, to, an"
28357,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.111111111,"that, has, origin, and, is"
28358,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.111111111,"is, that, the, be, identified, and"
28359,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.111111111,"that, has, the, origin, ratg13"
28360,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.111111111,"with, other, sars-cov-2"
28361,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.111111111,"the, natural, of, coronaviruses"
28362,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.111111111,"to, the, of, sars-cov-2, natural"
28363,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.111111111,"be, the, sars-cov-2, its"
28364,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.111111111,"of, sars-cov-2, to, be, with"
28365,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.111111111,"nucleotide, bat, of, sars-cov-2, and, sars-cov"
28366,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.111111111,"from, bat, and, nucleotide"
28367,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.111111111,"of, sars-cov-2, from, their, and"
28368,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.111111111,"the, was, to, which, rbd, of"
28369,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.111111111,"of, sars-cov-2, the, which, animals"
28370,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.111111111,"the, of, sars-cov-2, to, also"
28371,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.111111111,"the, two, in, that, sequences, a"
28372,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.111111111,"the, of, et, al., that, may, to, this, hypothesis"
28373,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.111111111,"the, that, sars-cov-2, with, of, complete, and, to"
28374,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.111111111,"to, that, the, of, this"
28375,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.111111111,"and, that, is, most, of"
28376,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.111111111,"the, of, to, that, this"
28377,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.111111111,"of, evidence, that, the, is, origin"
28378,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.111111111,"is, the, to, be, of"
28379,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.111111111,"that, the, bats, be"
28380,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.111111111,"sars-cov-2, that, the, or, hosts, for"
28381,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.111111111,"the, sars-cov-2, be, its"
28382,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.111111111,"studies, on, suggest, the, based"
28383,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.111111111,"sars-cov-2, contains, the, that, to, from"
28384,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.111111111,"to, all, from, a, sars-cov-2"
28385,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.111111111,"the, to, a, from, also"
28386,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.111111111,"the, to, that, sars-cov-2, from"
28387,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.111111111,"scientific, and, that, for"
28388,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.111111111,"that, sars-cov-2, and, bats"
28389,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.111111111,"virus, genome, the, covid-19, that"
28390,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.111111111,"that, the, also, virus"
28391,The COVID-19 most likely developed from bat origin coronaviruses,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.111111111,"the, covid-19, likely"
28392,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.111111111,"the, for, more, likely"
28393,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.111111111,"closely, related, to, a, at, the, is"
28394,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.111111111,"in, the, group, of, a, to, study, by, found, genome, were, present, that, from"
28395,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.111111111,"is, a, virus, that, found, to, the"
28396,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.111111111,"of, the, in, that, was, by"
28397,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.111111111,"the, from, were, in, by, of, a, to, et, al., that, at, virus"
28398,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.111111111,"the, as, are, bats"
28399,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.111111111,"the, sars-cov-2, to, a, is, bat"
28400,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.111111111,"that, a, bat, sars-cov-2"
28401,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.111111111,"a, are, for, the"
28402,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.111111111,"a, the, of, virus, and, that, to"
28403,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.111111111,"the, of, to, a, virus"
28404,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.111111111,"the, of, that, a, virus"
28405,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.111111111,"the, patients, in, china, a, of"
28406,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.111111111,"the, outbreak, a, in, wuhan,"
28407,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.111111111,"sars-cov-2, a, the, of, at, genome"
28408,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.111111111,"(2020), a, of, sars-cov-2, in, the"
28409,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.111111111,"sars-cov-2, the, at, of, complete"
28410,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.111111111,"was, a, bat, similarity, to"
28411,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.111111111,"from, a, in, bat"
28412,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.111111111,"a, similarity, genome, to"
28413,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.111111111,"to, of, yunnan, a, bat"
28414,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.111111111,"to, of, which, from, a"
28415,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.111111111,"a, shows, to, of, which, in"
28416,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.111111111,"from, a, bat, to, in"
28417,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.111111111,"a, which, bat, ratg13,, in, from"
28418,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.111111111,"the, is, to, and, in"
28419,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.111111111,"the, in, and, for, a, of"
28420,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.111111111,"in, a, and, which, to, sars-cov-2, the"
28421,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.111111111,"(2020), a, of, sars-cov-2, the, in"
28422,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.111111111,"(2020), the, of, sars-cov-2, and, viruses"
28423,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.111111111,"sars-cov-2, of, the, and, viruses, to, in, binding"
28424,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.111111111,"and, which, have, to, of, found, in"
28425,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.111111111,"genomic, of, similar, to"
28426,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.111111111,"have, and, of, et, genome, to"
28427,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.111111111,"are, for, be, in, with, that, an"
28428,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.111111111,"in, study, possible, with"
28429,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.111111111,"are, in, animals, be"
28430,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.111111111,"study, sars-cov-2, be, an"
28431,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.111111111,"and, sars-cov-2, are, to, pangolin, a"
28432,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.111111111,"sars-cov-2, have, been, to, a, are, and"
28433,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.111111111,"and, suggest, that, have, the, of"
28434,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.111111111,"been, that, the, of, are"
28435,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.111111111,"of, the, virus, and, with, ratg13,"
28436,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.111111111,"the, and, one, of, a, to"
28437,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.111111111,"the, that, of, are, with, and, one"
28438,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.111111111,"natural, of, the, spike, in, a, sars-cov-2,, that"
28439,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.111111111,"sars-cov-2, have, been, to, as"
28440,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.111111111,"to, sars-cov-2, the, as"
28441,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.111111111,"sars-cov-2, have, been"
28442,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.111111111,"we, the, to"
28443,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.111111111,"the, identify, as"
28444,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.111111111,"and, sars-cov-2, in, a, viruses"
28445,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.111111111,"the, viruses, and, of, that"
28446,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.111111111,"a, the, of, and, in, with, that"
28447,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.111111111,"two, of, sars-cov-2, in, and"
28448,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.111111111,"the, that, in, a, two"
28449,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.111111111,"the, of, sars-cov-2, a, in"
28450,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.111111111,"the, and, viruses, in"
28451,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.111111111,"that, the, of, in, viruses, a"
28452,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.111111111,"a, and, in, the, that"
28453,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.111111111,"the, results, that, in, with"
28454,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.111111111,"the, a, two, that, sequences, in"
28455,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.111111111,"sars-cov-2, to, cov"
28456,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.111111111,"and, the, of, bat, clusters, viruses, are, as, cluster, with, other, into"
28457,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.111111111,"in, the, that, are, to, and, for"
28458,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.111111111,"that, the, evidence, and, to, provide"
28459,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.111111111,"the, are, or, bats, in, and"
28460,"Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.111111111,"based, on, the, that, to, in"
28461,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.111111111,"bats, and, pangolins, the, or, in"
28462,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.111111111,"in, these, viruses, are, 2, and, that, the"
28463,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.111111111,"with, the, sars-cov-2, is, bat"
28464,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.111111111,"we, that, the, are, more"
28465,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.111111111,"this, is, with, at, the"
28466,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.111111111,"the, is, more, than, bat, for"
28467,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.111111111,"within, this, are, bat, the, same"
28468,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.111111111,"of, and, that, the, from, bats"
28469,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.111111111,"from, and, the, of, sars-cov-2"
28470,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.111111111,"that, sars-cov-2, bats, and, from"
28471,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.111111111,"that, bats, and, sars-cov-2"
28472,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.111111111,"and, (2020), of, sars-cov-2, the, viruses"
28473,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.111111111,"because, viruses, in, to, the"
28474,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.111111111,"in, to, the, we, that, this, is, sars-cov-2."
28475,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.111111111,"between, sars-cov-2, and, the, bat, in"
28476,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.111111111,"pangolin, and, to, sars-cov-2."
28477,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.111111111,"that, to, is, in, pangolin, sars-cov-2, the"
28478,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.111111111,"and, in, to, the, sars-cov-2, is"
28479,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.111111111,"all, cov, that, origin, in, different, and"
28480,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.111111111,"with, the, and, all, that, in, this, is, difference, between, sars-cov-2, sars, than"
28481,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.111111111,"sars-cov-2, viruses, that, are, ratg13, and"
28482,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.111111111,"these, are, 2, viruses, the, in, and, that"
28483,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.111111111,"this, the, bat, pangolin, origin, cov"
28484,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.111111111,"to, have, with, the, which, bat"
28485,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.111111111,"is, sars-cov-2, or, in"
28486,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.111111111,"the, which, to, with, pangolin, bat"
28487,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.111111111,"in, to, is, the, which, originated"
28488,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.111111111,"ratg13, the, which, with, sars-cov-2"
28489,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.111111111,"the, sars-cov-2, to, is, likely, or"
28490,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.111111111,"the, in, very, to, sars-cov-2"
28491,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.111111111,"have, pangolin, with, to, the, sars-cov-2"
28492,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.111111111,"sars-cov-2, to, pangolin, cov, the"
28493,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.111111111,"of, to, that, sars-cov-2, by, the, and"
28494,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.111111111,"the, of, and, that, sars-cov-2, is, to, by"
28495,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.111111111,"to, and, of, is, that, ratg13, in, bat"
28496,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.111111111,"the, of, this, origin"
28497,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.111111111,"of, the, or"
28498,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.111111111,"bat, cov, pangolin, this, the, origin"
28499,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.111111111,"sars-, the, of, probable, origin"
28500,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.111111111,"the, sars-cov-2, are, bats"
28501,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.111111111,"sars-cov-2, that, bats, using, the"
28502,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.111111111,"are, this, in, the, that"
28503,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.111111111,"and, sars-cov-2, bat, pangolin, which"
28504,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.111111111,"and, that, the, bat, ratg13"
28505,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.111111111,"the, which, is, that, and"
28506,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.111111111,"the, pangolin, similarity, sars-cov-2"
28507,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.111111111,"that, sars-cov-2, similarity, and"
28508,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.111111111,"the, observed, that, bat"
28509,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.111111111,"has, sars-cov-2, with, the, bat"
28510,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.111111111,"the, that, has, origin"
28511,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.111111111,"origin, the, that, ratg13, has"
28512,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.111111111,"the, that, origin"
28513,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.111111111,"that, sars-cov-2, bats, the"
28514,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.111111111,"are, more, sars-cov-2, than, the"
28515,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.111111111,"origin, of, sars-cov-2, the"
28516,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.111111111,"the, origin, of, and, sars-cov-2"
28517,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.111111111,"this, the, of, sars-cov-2, pangolin"
28518,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.111111111,"the, sars-cov-2, of, their"
28519,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.111111111,"and, sars-cov-2, bat, pangolin, viruses"
28520,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.111111111,"the, viruses, and, bat, that"
28521,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.111111111,"bat, cov, that, and, sars-cov-2"
28522,Bats are likely reservoir hosts for SARS-CoV-2,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.111111111,"bats, sars-cov-2"
28523,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.111111111,"sars-cov-2, bats, in, this"
28524,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.111111111,"in, that, sars-cov-2, may, have"
28525,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.111111111,"that, bats, may, have, sars-cov-2"
28526,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.111111111,"the, of, that, may, as, evidence, to"
28527,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.111111111,"to, consistent, and, provide, the, sars-cov-2"
28528,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.111111111,"the, probable, origin, of, sars-"
28529,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.111111111,"that, sars-cov-2, may, have, bats"
28530,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.111111111,"the, of, to, that, sars-cov-2, bats"
28531,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.111111111,"bats, are, hosts, of, and, to, that, as"
28532,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.111111111,"the, origin, virus, in, and"
28533,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.111111111,"the, genome, of, and, bat, sequences, in"
28534,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.111111111,"studies, the, of, covs, and, these"
28535,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.111111111,"of, virus, the, bat, and"
28536,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.111111111,"suggest, the, based, on, studies"
28537,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.111111111,"of, bat, from, in, china"
28538,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.111111111,"studies, and, that, the, of"
28539,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.111111111,"of, sars-cov-2, and, to, on"
28540,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.111111111,"of, the, genome, and, other"
28541,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.111111111,"the, genome, of, that, to, and"
28542,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.111111111,"sars-cov-2, to, the, cov, pangolin"
28543,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.111111111,"the, that, origin, sars-cov-2."
28544,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.111111111,"of, the, a, similar, to, that"
28545,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.111111111,"the, of, with, clustering, that, sars-cov-2"
28546,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.111111111,"ratg13, the, of, with, sars-cov-2"
28547,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.111111111,"to, sars-cov-2, a, of, the, that, with"
28548,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.111111111,"that, a, of, the, likely"
28549,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.111111111,"that, sars-cov-2, likely, to"
28550,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.111111111,"that, to, and, sars-cov-2"
28551,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.111111111,"to, sars-cov-2, and, has, that, with"
28552,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.111111111,"has, that, sars-cov-2"
28553,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.111111111,"that, with, to, and, sars-cov-2"
28554,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.111111111,"and, that, sars-cov-2, with"
28555,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.111111111,"that, similarity, sars-cov-2, and"
28556,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.111111111,"to, the, and, is, sars-cov"
28557,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.111111111,"to, of, with, sars-cov-2"
28558,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.111111111,"the, of, identity, with, and"
28559,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.111111111,"but, is, of, the, and"
28560,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.111111111,"with, and, the"
28561,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.111111111,"identity, with, of"
28562,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.111111111,"of, sars-cov-2, and, the"
28563,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.111111111,"is, sars-cov-2, of"
28564,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.111111111,"is, of, sars-cov-2, the"
28565,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.111111111,"and, of, the, is"
28566,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.111111111,"of, with, and, the, sars-cov-2"
28567,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.111111111,"sars-cov-2, identity, the, of"
28568,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.111111111,"the, and, from"
28569,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.111111111,"that, the, between, and"
28570,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.111111111,"and, provide, the, sars-cov-2"
28571,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.111111111,"that, the, sars-cov-2, in"
28572,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.111111111,"the, of, that, for"
28573,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.111111111,"sars-cov-2, that, and"
28574,"civet cats and raccoon dogs  

are the intermediate hosts","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.111111111,"civet, and, the"
28575,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.111111111,"a, the, cov, in"
28576,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.111111111,"a, in, the, originated, from"
28577,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.111111111,"bats, the, sars-cov, of, for, and"
28578,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.111111111,"that, the, of, and, mers-cov, sars-cov"
28579,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.111111111,"are, the, that, and"
28580,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.111111111,"of, the, for, have"
28581,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.111111111,"and, that, the, of, bats, are, hosts"
28582,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.111111111,"is, the, similarity, and"
28583,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.111111111,"the, similarity, is, for"
28584,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.111111111,"the, sars-cov-2, in"
28585,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.111111111,"in, the, are, to, and"
28586,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.111111111,"are, sars-cov-2, to, and, in"
28587,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.111111111,"to, sars-cov-2, in, the, binding"
28588,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.111111111,"and, to, the"
28589,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.111111111,"the, sars-cov-2, to, and"
28590,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.111111111,"to, the, and, are, sars-cov-2"
28591,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.111111111,"the, of, that, and"
28592,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.111111111,"that, virus, in, of"
28593,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.111111111,"the, that, virus, in, this"
28594,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.111111111,"the, that, to, at, and, with"
28595,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.111111111,"the, of, and, has"
28596,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.111111111,"that, the, complete, sars-cov-2, to, with, of, and"
28597,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.111111111,"of, and, be, the"
28598,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.111111111,"that, the, and, this"
28599,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.111111111,"and, the, of, bat, that, this, in, recombination, can"
28600,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.111111111,"the, was, that, transmitted, from, to"
28601,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.111111111,"from, the, of, that, sars-cov-2, to"
28602,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.111111111,"that, not, was, sars-cov-2, to, from"
28603,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.111111111,"to, sars-cov-2, the, rbd, that, of"
28604,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.111111111,"the, from, that, sars-cov-2, to"
28605,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.111111111,"to, that, the, of, bats, sars-cov-2"
28606,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.111111111,"that, sars-cov-2, to, identical, the"
28607,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.111111111,"the, sars-cov-2, at, that, in"
28608,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.111111111,"the, to, that, virus, in"
28609,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.111111111,"in, to, the, of, sars-cov-2, is"
28610,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.111111111,"the, rbd, in, to, bind, that, of"
28611,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.111111111,"the, sars-cov-2, for, host"
28612,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.111111111,"this, the, sars-cov-2, pangolin"
28613,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.111111111,"the, genome,, sars-cov-2, to, of"
28614,COVID-19 is a zoonotic virus,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.111111111,"a, zoonotic, virus"
28615,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.111111111,"the, of, virus, to, with, a"
28616,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.111111111,"the, of, virus, to, by"
28617,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.111111111,"a, due, to, recombination, with, the"
28618,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.111111111,"of, the, zoonotic, with, to, virus, rbd"
28619,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.111111111,"that, was, first, in"
28620,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.111111111,"that, the, was, in"
28621,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.111111111,"identify, as, the"
28622,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.111111111,"observed, that, the, bat"
28623,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.111111111,"that, the, origin, sars-cov-2."
28624,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.111111111,"sars-cov-2, be, to"
28625,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.111111111,"sars-cov-2, from, to, likely, studies"
28626,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.111111111,"is, to, that, from"
28627,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.111111111,"that, from, very, to, such"
28628,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.111111111,"that, from, be"
28629,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.111111111,"to, that, is, be"
28630,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.111111111,"the, most, they, of"
28631,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.111111111,"of, the, that, they"
28632,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.111111111,"is, sars-cov-2, the, that"
28633,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.111111111,"sars-cov-2, bat, the, host"
28634,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.111111111,"sars-cov-2, and, the, of, bat"
28635,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.111111111,"the, of, present, and"
28636,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.111111111,"study, of, bat, sars-cov-2"
28637,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.111111111,"cov, and, the"
28638,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.111111111,"the, be, a"
28639,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.111111111,"an, sars-cov-2, and, the"
28640,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.111111111,"the, an, sars-cov-2, virus"
28641,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.111111111,"and, a, the, virus"
28642,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.111111111,"study, be, sars-cov-2, an"
28643,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.111111111,"a, virus, and, the, sars-cov-2"
28644,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.111111111,"the, and, sars-cov-2, a"
28645,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.111111111,"in, is, of, the, virus, has"
28646,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.111111111,"has, at, the, of, sars-cov-2"
28647,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.111111111,"the, animal, for, of"
28648,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.111111111,"the, that, sars-cov-2, a, from"
28649,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.111111111,"a, still, that, sars-cov-2, from"
28650,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.111111111,"a, that, sars-cov-2, originated, the"
28651,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.111111111,"in, the, originated, from, a"
28652,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.111111111,"the, natural, of, sites"
28653,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.111111111,"an, of, to, and, the"
28654,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.111111111,"the, of, to, is, natural, not"
28655,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.111111111,"and, natural, of, the, is"
28656,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.111111111,"of, sars-cov-2, in, region"
28657,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.111111111,"from, in, china, bat, of"
28658,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.111111111,"study, bat, of, sars-cov-2"
28659,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.111111111,"sars-cov-2, from, including, of, coronaviruses"
28660,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.111111111,"a, the, also, and, for"
28661,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.111111111,"a, origin, and, zoonotic"
28662,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.111111111,"are, the, for, a"
28663,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.111111111,"found, of, to, sars-cov-2, in"
28664,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.111111111,"of, sars-cov-2, with, to, be"
28665,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.111111111,"cause, of, in, related, to, bats"
28666,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.111111111,"bats, to, covs, related, that, are, hosts"
28667,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.111111111,"to, that, of, bats, and, as, hosts, are"
28668,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.111111111,"has, found, the, in"
28669,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.111111111,"the, in, which, was"
28670,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.111111111,"protein, that, similar, of, in"
28671,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.111111111,"the, to, that, was"
28672,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.111111111,"the, was, detected, in, of"
28673,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.111111111,"similar, to, the, in, of, that"
28674,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.111111111,"the, of, spike, to, natural, a, that"
28675,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.111111111,"the, of, sars-cov-2,, in, spike, that, natural, a"
28676,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.111111111,"that, similar, to, a, the, of"
28677,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.111111111,"the, to, sars-cov-2,, amino, in, of"
28678,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.111111111,"to, the, that, sars-cov-2, of, from, natural"
28679,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.111111111,"and, the, of, to, be, that, sars-cov-2, is, natural"
28680,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.111111111,"that, bats, are, the, hosts, of, and"
28681,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.111111111,"coronavirus, the, of, is, be, in, to"
28682,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.111111111,"in, the, of, sars-cov-2,"
28683,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.111111111,"the, bat, coronavirus, ratg13, of"
28684,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.111111111,"the, is, to, of, coronavirus"
28685,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.111111111,"the, sequence, of, coronavirus, to, bat"
28686,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.111111111,"the, is, of, to, in"
28687,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.111111111,"the, known, is, of, to"
28688,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.111111111,"to, the, of, is, be"
28689,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.111111111,"of, amino, the, in, to, sars-cov-2,"
28690,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.111111111,"has, the, of, to, in, region"
28691,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.111111111,"also, ace2, in, a, of, and, that, the"
28692,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.111111111,"in, the, rbd, of, to, that, bind"
28693,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.111111111,"in, that, similar, to, of"
28694,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.111111111,"of, to, it, is, possible, and"
28695,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.111111111,"bat, and, to, in, of"
28696,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.111111111,"in, and, to, that, is, of, bat, ratg13"
28697,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.111111111,"research, groups, sars-cov-2, highly, as"
28698,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.111111111,"of, from, found, malayan, sars-cov-2, coron-, avirus"
28699,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.111111111,"of, from, coronaviruses, including, sars-cov-2"
28700,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.111111111,"protein, that, of, intermediate, as, pangolin"
28701,"Bats have been reported as being the rich source of 

coronaviruses","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.111111111,"have, as, the, of"
28702,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.111111111,"of, to, that, the, pangolin-cov"
28703,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.111111111,"s, the, of, to, study, sars-cov-2."
28704,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.111111111,"pangolin, to, the, of, sars-cov-2."
28705,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.111111111,"of, sars-, cov-2, more"
28706,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.111111111,"in, many, genetic, similar, to, and"
28707,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.111111111,"the, virus, similar, to, and, in"
28708,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.111111111,"in, the, of, virus, to, sars-cov-2, with, and"
28709,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.111111111,"in, with, sars-, and, similar, to, sars-cov-2, the"
28710,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.111111111,"to, in, recent, with, sars-cov-2, the, rmyn02,, and"
28711,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.111111111,"analysis, the, virus, in, and, to, of"
28712,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.111111111,"and, of, sars-cov-2, in, binding, the, viruses, to"
28713,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.111111111,"to, the, of, rbd, zoonotic, virus, with"
28714,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.111111111,"bat, the, of, sars-cov-2, and, similarity"
28715,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.111111111,"the, of, to, sars-cov-2."
28716,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.111111111,"the, of, coronaviruses, and, sars-cov-2"
28717,The COVID-19 most likely developed from bat origin coronaviruses,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.111111111,"the, bat, coronaviruses"
28718,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.111111111,"the, of, sars-cov-2, identity"
28719,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.111111111,"to, sars-cov-2, similarity, the, of"
28720,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.111111111,"the, of, pangolin, to, sars-cov-2."
28721,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.111111111,"that, a, the, is"
28722,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.111111111,"a, analysis, that, the"
28723,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.111111111,"that, sars-cov-2, a, the"
28724,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.110344828,"that, had, zoonotic, the, animal, over, with, of, occurred, in, further, not, have, but, to, live"
28725,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.110344828,"of, the, have, to, live, animal, in, but, not, with, had, over, further, that, occurred, zoonotic"
28726,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.110169492,"evidence, in, the, and, that, of, positive, collected, were, to, from, located, market"
28727,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.110169492,"one, study, found, evidence, that, with, the, of, to, as, an, intermediate, host"
28728,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.110169492,"in, the, who-china, and, that, of, were, to, vendors, huanan, all, between, market"
28729,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.110169492,"in, the, of, located, from, that, positive, market, collected, to, were, and, evidence"
28730,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.110169492,"the, huanan, and, of, all, to, who-china, that, were, in, vendors, between, market"
28731,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.110169492,"as, of, the, an, to, with, evidence, one, study, found, that, intermediate, host"
28732,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.110091743,"this, that, were, from, in, the, a, at, and, of, are, viruses"
28733,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.110091743,"the, of, to, are, as, a, that, this, in, for, virus, is"
28734,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.110091743,"december, the, of, an, was, confirmed, a, outbreak, at, were, to, and"
28735,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.110091743,"in, may, the, animal, of, that, for, as, also, species, a, and"
28736,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.110091743,"with, the, and, for, to, that, in, between, sars-cov-2, be, than, other"
28737,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.110091743,"in, a, of, to, the, are, virus, that, this, is, for, as"
28738,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.110091743,"may, also, in, a, of, animal, species, and, that, the, as, for"
28739,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.110091743,"an, outbreak, a, the, at, was, december, and, of, were, to, confirmed"
28740,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.110091743,"a, of, the, from, this, that, and, are, at, in, viruses, were"
28741,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.110091743,"that, and, be, for, sars-cov-2, to, other, than, the, between, in, with"
28742,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.11,"bats, the, can, be, of, are, to, as, and, in, also"
28743,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.11,"the, of, have, a, to, live, in, animals, market, were, was"
28744,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.11,"cases, the, of, or, to, that, in, this, those, than, market"
28745,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.11,"and, the, of, bat, to, similar, viruses, are, a, that, in"
28746,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.11,"the, of, and, bat, that, a, in, viruses, are, similar, to"
28747,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.11,"can, a, virus, bat, to, bats, of, and, are, as, they"
28748,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.11,"a, in, that, the, virus, is, closely, related, to, of, bats"
28749,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.11,"this, of, cases, to, the, market, than, those, in, that, or"
28750,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.11,"and, of, bat, to, are, as, a, bats, they, can, virus"
28751,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.11,"bats, are, also, as, the, of, can, and, be, in, to"
28752,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.11,"the, of, market, in, was, to, live, animals, were, have, a"
28753,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.11,"the, of, to, a, closely, related, bats, that, in, virus, is"
28754,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.10989011,"in, a, of, the, we, are, that, this, from, were"
28755,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.10989011,"the, market, officials, in, of, chinese, and, a, but, an"
28756,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.10989011,"the, only, that, have, in, of, cases, to, a, early"
28757,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.10989011,"and, an, experts, from, to, in, virus., there, was, any"
28758,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.10989011,"a, of, the, from, we, this, that, are, in, were"
28759,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.10989011,"the, of, that, as, at, virus, was, a, is, evidence"
28760,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.10989011,"in, a, cluster, of, for, to, infected, with, that, events"
28761,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.10989011,"the, in, of, an, to, that, this, was, also, virus"
28762,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.10989011,"is, evidence, at, that, the, virus, was, as, of, a"
28763,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.10989011,"and, from, in, were, found, to, that, the, of, likely"
28764,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.10989011,"the, of, time, that, is, a, virus, in, animal, for"
28765,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.10989011,"there, experts, was, an, virus., to, from, and, any, in"
28766,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.10989011,"in, chinese, officials, the, market, but, an, and, a, of"
28767,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.10989011,"early, cases, in, only, the, of, that, a, have, to"
28768,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.10989011,"this, that, the, virus, was, an, of, in, also, to"
28769,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.10989011,"the, in, a, for, of, is, time, that, virus, animal"
28770,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.10989011,"of, infected, to, a, cluster, with, that, in, for, events"
28771,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.10989011,"the, of, and, were, that, from, found, in, likely, to"
28772,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.109756098,"the, virus, has, an, which, to, that, of, and"
28773,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.109756098,"the, that, virus, to, after, a, of, and, has"
28774,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.109756098,"the, covid-19, of, sars-cov-2, or, to, a, virus, in"
28775,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.109756098,"bats, the, by, species, of, are, and, has, been"
28776,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.109756098,"the, animals, to, in, spread, bats,, was, and, other"
28777,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.109756098,"a, by, from, at, in, that, the, of, were"
28778,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.109756098,"the, of, a, live, animal, in, and, animals, market"
28779,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.109756098,"when, a, to, humans, for, the, first, it, is"
28780,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.109756098,"are, they, in, to, of, the, virus, genetic, and"
28781,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.109756098,"analysis, as, the, dna, was, found, to, of, for"
28782,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.109756098,"of, which, has, to, virus, that, an, and, the"
28783,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.109756098,"and, the, to, are, a, bats, in, virus, its"
28784,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.109756098,"in, the, of, and, are, to, they, genetic, virus"
28785,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.109756098,"of, to, the, was, analysis, dna, for, found, as"
28786,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.109756098,"for, the, of, and, found, or, with, as, to"
28787,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.109756098,"sars-cov, as, and, to, was, for, the, of, suggested"
28788,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.109756098,"it, to, when, first, the, humans, a, is, for"
28789,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.109756098,"in, the, and, to, that, of, bat, ratg13, are"
28790,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.109756098,"of, has, to, a, virus, that, after, and, the"
28791,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.109756098,"of, the, found, identified, and, these, with, huanan, seafood"
28792,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).",0.109756098,"these, such, as, and, the, of, to, et, al.,, 2021;, 2021)., it, can, that, emergence, sars-cov-2, is, natural"
28793,"The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.109756098,"the, emergence, of, is, natural, et, al.,, 2021)., to, these, and, sars-cov-2, it, that, can, such, as, 2021;"
28794,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.109756098,"a, of, in, that, animal, for, with, the, or"
28795,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.109756098,"sars-cov-2, of, covid-19, to, a, virus, or, in, the"
28796,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.109756098,"its, are, and, the, virus, bats, to, a, in"
28797,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.109756098,"the, of, and, identified, with, found, these, huanan, seafood"
28798,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.109756098,"in, a, of, animal, that, the, with, or, for"
28799,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.109756098,"as, the, found, to, or, with, of, for, and"
28800,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.109756098,"to, the, in, of, and, that, a, role, outbreak"
28801,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.109756098,"the, was, in, bats,, and, spread, to, other, animals"
28802,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.109756098,"most, animal, by, in, the, are, with, bats,, other"
28803,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.109756098,"in, the, role, of, a, outbreak, that, to, and"
28804,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.109756098,"has, been, bats, and, are, the, of, species, by"
28805,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.109756098,"in, the, market, live, animal, and, a, of, animals"
28806,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.109756098,"the, are, in, bats,, with, most, by, animal, other"
28807,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.109756098,"suggested, as, the, was, to, sars-cov, of, for, and"
28808,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.109756098,"a, of, the, from, by, that, at, in, were"
28809,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.109756098,"the, of, and, bat, that, in, ratg13, are, to"
28810,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.109756098,"the, and, zc45, in, to, that, are, of, sars-cov-2,"
28811,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.109756098,"zc45, and, in, to, sars-cov-2,, that, the, of, are"
28812,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.109589041,"a, as, the, of, is, in, with, to"
28813,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.109589041,"sars-cov-2, receptor-binding, to, human, ace2, in, or, after"
28814,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.109589041,"in, of, as, intermediate, that, were, and, more"
28815,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.109589041,"the, animal, to, have, and, reservoirs, including, humans"
28816,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.109589041,"as, a, of, the, in, is, to, with"
28817,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.109589041,"are, a, to, recombination, in, with, the, and"
28818,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.109589041,"the, of, to, animal, in, wet, market, were"
28819,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.109589041,"bats, the, can, be, of, are, to, and"
28820,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.109589041,"by, and, in, their, the, of, sars-cov-2, origin"
28821,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.109589041,"in, a, of, sars-cov-2, were, origin, that, zoonotic"
28822,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.109589041,"of, the, that, cases, and, case, with, huanan"
28823,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.109589041,"to, sars-cov-2, from, a, of, in, the, that"
28824,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.109589041,"cases, at, the, market,, be, that, sars-cov-2, by"
28825,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.109589041,"this, is, the, same, we, that, are, for"
28826,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.109589041,"found, that, the, of, have, to, as, sars-cov-2."
28827,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.109589041,"the, not, it, appear, that, in, of, animals"
28828,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.109589041,"a, of, market, in, that, with, the, to"
28829,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.109589041,"the, of, an, was, that, humans, to, and"
28830,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.109589041,"transmission, of, bats, to, found, with, analysis, the"
28831,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.109589041,"be, transmission, to, another, bats, of, and, as"
28832,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.109589041,"of, an, intermediate, that, humans, to, and, more"
28833,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.109589041,"a, and, coronaviruses, be, as, to, coronavirus, bats"
28834,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.109589041,"sars-cov-2, receptor-binding, to, human, ace2, or, after, in"
28835,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.109589041,"on, the, of, in, protein, that, coronavirus, a"
28836,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.109589041,"that, the, sequences, of, genomes, and, sars-cov, a"
28837,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.109589041,"coronaviruses, and, a, to, coronavirus, bats, be, as"
28838,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.109589041,"as, a, species, that, from, to, bat, and"
28839,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.109589041,"the, of, sars-cov, and, that, sequences, a, genomes"
28840,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.109589041,"the, of, as, host, a, from, were, and"
28841,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.109589041,"analysis, bats, the, found, to, with, of, transmission"
28842,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.109589041,"in, the, as, an, from, to, moreover,, and"
28843,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.109589041,"for, the, of, and, species, barrier, humans, to"
28844,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.109589041,"and, the, it, be, for, of, sars-cov-2, by"
28845,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.109589041,"from, in, the, of, that, a, sars-cov-2, to"
28846,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.109589041,"coronaviruses, to, sars-cov-2, in, the, that, result, of"
28847,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.109589041,"evidence, to, that, the, of, bats, and, sars-cov-2"
28848,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.109589041,"the, to, have, humans, and, animal, reservoirs, including"
28849,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.109589041,"are, a, the, recombination, and, in, with, to"
28850,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.109589041,"the, of, with, case, and, cases, huanan, that"
28851,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.109589041,"that, the, of, in, to, with, a, market"
28852,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.109589041,"the, of, to, barrier, species, for, humans, and"
28853,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.109589041,"a, in, the, that, from, human, or, for"
28854,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.109589041,"and, that, of, were, in, more, intermediate, as"
28855,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.109589041,"the, of, and, that, an, was, to, humans"
28856,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.109589041,"humans, and, more, that, of, to, an, intermediate"
28857,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.109589041,"the, of, were, as, a, host, from, and"
28858,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.109589041,"moreover,, in, to, the, from, and, as, an"
28859,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.109589041,"the, cases, that, be, sars-cov-2, at, market,, by"
28860,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.109589041,"the, of, sars-cov-2, be, it, for, and, by"
28861,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.109589041,"to, sars-cov-2, result, of, in, the, that, coronaviruses"
28862,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.109589041,"and, in, related, that, the, of, is, sars-cov-2"
28863,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.109589041,"the, been, a, of, that, to, rhinolophus, and"
28864,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.109589041,"the, of, in, appear, it, animals, that, not"
28865,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.109589041,"bats, as, to, be, of, another, transmission, and"
28866,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.109589041,"the, of, were, to, wet, animal, market, in"
28867,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.109589041,"from, and, the, of, sars-cov-2, have, been, in"
28868,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.109589041,"a, and, from, bat, species, as, to, that"
28869,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.109589041,"to, the, been, of, rhinolophus, and, that, a"
28870,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.109589041,"of, the, sars-cov-2, have, been, in, from, and"
28871,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.109589041,"a, in, the, that, sars-cov-2, from, laboratory, for"
28872,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.109589041,"that, the, of, may, have, to, as, intermediate"
28873,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.109589041,"origin, of, the, by, sars-cov-2, and, in, their"
28874,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.109589041,"in, the, by, and, to, sars-cov-2, is, of"
28875,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.109589041,"and, in, to, the, of, is, natural, sars-cov-2"
28876,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.109589041,"this, the, in, that, are, more, sars-cov-2, than"
28877,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.109589041,"are, 2, and, sars-cov-2, with, pangolin, that, the"
28878,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.109589041,"on, in, the, protein, of, a, coronavirus, that"
28879,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.109589041,"the, we, are, that, this, is, for, same"
28880,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.109589041,"that, 2, pangolin, with, and, are, the, sars-cov-2"
28881,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.109589041,"by, and, in, to, the, of, sars-cov-2, is"
28882,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.109589041,"that, are, more, than, the, sars-cov-2, in, this"
28883,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.109589041,"evidence, to, sars-cov-2, of, bats, the, and, that"
28884,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.109589041,"for, the, that, from, a, in, human, or"
28885,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.109589041,"from, for, the, that, sars-cov-2, in, a, laboratory"
28886,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.109589041,"a, origin, of, that, sars-cov-2, zoonotic, in, were"
28887,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.109589041,"sars-cov-2, the, and, in, related, that, of, is"
28888,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.109589041,"and, in, to, the, of, sars-cov-2, natural, is"
28889,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.109589041,"of, to, have, the, that, found, as, sars-cov-2."
28890,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.109589041,"intermediate, as, to, the, of, that, may, have"
28891,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.109375,"of, the, in, a, sars-cov-2,, that, naturally"
28892,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.109375,"sars-cov-2, and, viruses, to, in, genetic, many"
28893,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.109375,"that, of, bats, and, for, more, than"
28894,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.109375,"of, from, infected, were, and, more, than"
28895,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.109375,"from, the, of, may, have, to, spillover"
28896,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.109375,"genetic, have, the, in, and, to, a"
28897,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.109375,"is, between, and, of, sars-cov-2, to, be"
28898,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.109375,"in, is, sars-cov-2, the, amino, acid, of"
28899,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.109375,"of, the, emergence, and, viruses, to, many"
28900,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.109375,"with, the, to, that, sars-cov-2, bat, as"
28901,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.109375,"sars-cov-2, between, and, can, be, to, that"
28902,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.109375,"to, and, their, can, with, the, of"
28903,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.109375,"that, the, with, of, virus, and, to"
28904,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.109375,"to, recombination, the, of, a, virus, with"
28905,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.109375,"to, of, in, the, it, suggested, that"
28906,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.109375,"as, the, to, sars-cov, for, transmission, and"
28907,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.109375,"the, to, species, and, which, other, including"
28908,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.109375,"the, with, and, that, humans, at, in"
28909,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.109375,"that, been, with, to, and, potentially, sars-cov-2"
28910,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.109375,"in, to, sars-cov-2, been, host,, and, a"
28911,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.109375,"viruses, are, sars-cov-2, bat, this, that, the"
28912,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.109375,"of, lineage, a, at, the, by, from"
28913,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.109375,"the, origin, were, that, in, and, humans"
28914,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.109375,"of, the, are, in, viruses, from, a"
28915,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.109375,"the, that, of, zoonotic, origin, by, a"
28916,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.109375,"in, the, that, humans, at, and, with"
28917,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.109375,"a, of, the, from, lineage, by, at"
28918,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.109375,"sars-cov-2, of, on, and, zoonotic, to, in"
28919,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.109375,"to, have, the, of, may, from, spillover"
28920,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.109375,"that, were, from, the, this, virus, is"
28921,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.109375,"a, in, the, that, was, to, of"
28922,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.109375,"covid-19, is, to, have, the, market, in"
28923,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.109375,"scientists, have, that, the, of, to, sars-cov-2."
28924,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.109375,"that, were, the, and, animals, virus, is"
28925,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.109375,"the, of, that, but, evidence, was, to"
28926,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.109375,"the, virus, that, this, is, from, were"
28927,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.109375,"the, and, animals, virus, that, were, is"
28928,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.109375,"the, was, a, that, to, and, sequence"
28929,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.109375,"a, of, the, has, that, to, virus"
28930,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.109375,"the, of, can, and, with, their, to"
28931,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.109375,"the, of, a, that, virus, to, and"
28932,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.109375,"the, of, that, to, humans, by, and"
28933,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.109375,"and, from, in, to, the, bats, are"
28934,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.109375,"the, and, have, to, a, genetic, in"
28935,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.109375,"that, bats, the, and, have, in, china"
28936,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.109375,"origin, the, that, and, in, were, humans"
28937,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.109375,"the, of, human, is, natural, on, a"
28938,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.109375,"the, have, in, wet, wild, animals, market"
28939,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.109375,"the, that, of, with, seafood, market, in"
28940,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.109375,"sars-cov-2, is, a, and, to, which, that"
28941,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.109375,"and, the, to, it, that, sars-cov-2, is"
28942,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.109375,"the, to, be, of, is, bat, human"
28943,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.109375,"sars-cov, to, the, coronavirus, be, of, human"
28944,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.109375,"as, transmission, to, for, sars-cov, and, the"
28945,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.109375,"several, recently, to, that, of, sars-cov-2, and"
28946,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.109375,"a, of, the, from, are, in, viruses"
28947,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.109375,"in, the, those, of, pangolin, are, as"
28948,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.109375,"between, sars-cov-2, and, to, be, of, is"
28949,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.109375,"the, of, coronavirus, to, human, sars-cov, be"
28950,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.109375,"revealed, the, of, sars-cov-2, and, sars-cov, a"
28951,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.109375,"can, be, to, that, between, and, sars-cov-2"
28952,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.109375,"a, that, sars-cov-2, and, to, which, is"
28953,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.109375,"revealed, a, sars-cov-2, and, sars-cov, the, of"
28954,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.109375,"studies, the, of, a, and, which, as"
28955,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.109375,"that, was, the, of, evidence, but, to"
28956,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.109375,"may, of, that, the, serve, as, intermediate"
28957,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.109375,"in, a, of, to, the, that, was"
28958,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.109375,"the, of, in, a, similar, to, that"
28959,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.109375,"the, of, that, a, in, with, to"
28960,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.109375,"at, the, that, was, of, in, a"
28961,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.109375,"to, was, the, of, that, in, a"
28962,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.109375,"in, to, have, the, covid-19, is, market"
28963,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.109375,"lineage, b, and, the, was, of, sars-cov-2"
28964,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.109375,"to, sars-cov-2, from, a, of, in, the"
28965,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.109375,"a, for, the, of, and, in, that"
28966,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.109375,"studies, the, of, and, which, as, a"
28967,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.109375,"bats, the, natural, of, and, two, for"
28968,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.109375,"the, as, a, of, from, bats,, and"
28969,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.109375,"intermediate, it, for, the, sars-cov-2, in, a"
28970,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.109375,"sars-cov-2, been, to, a, host,, and, in"
28971,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.109375,"the, of, sars-cov-2, to, species, is, humans"
28972,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.109375,"to, that, sars-cov-2, the, bats, direct, of"
28973,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.109375,"a, origin, of, the, by, that, zoonotic"
28974,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.109375,"amino, at, the, in, similar, to, sars-cov-2,"
28975,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.109375,"it, that, the, sars-cov-2, and, to, is"
28976,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.109375,"the, of, that, may, serve, as, intermediate"
28977,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.109375,"these, are, to, the, in, and, that"
28978,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.109375,"of, to, humans, is, sars-cov-2, species, the"
28979,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.109375,"evidence, to, a, of, the, and, that"
28980,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.109375,"the, of, that, to, in, it, suggested"
28981,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.109375,"that, the, of, evidence, a, and, to"
28982,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.109375,"the, from, that, sars-cov-2, to, a, and"
28983,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.109375,"including, other, the, species, which, to, and"
28984,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.109375,"the, between, and, a, of, in, bat"
28985,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.109375,"the, a, species, of, by, bat, and"
28986,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.109375,"caves, can, of, the, in, viruses, bat"
28987,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.109375,"a, in, the, that, similar, to, of"
28988,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.109375,"in, yunnan, similar, to, that, of, the"
28989,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.109375,"of, scientists, to, have, the, that, sars-cov-2."
28990,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.109375,"the, are, with, and, genomic, these, in"
28991,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.109375,"the, a, of, from, to, by, and"
28992,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.109375,"more, than, were, from, of, infected, and"
28993,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.109375,"the, to, and, that, sequence, was, a"
28994,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.109375,"a, of, to, that, the, and, virus"
28995,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.109375,"markets, a, known, and, in, the, to"
28996,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.109375,"a, to, markets, and, the, in, known"
28997,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.109375,"that, the, with, in, seafood, market, of"
28998,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.109375,"are, genomic, in, with, these, the, and"
28999,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.109375,"and, also, of, in, is, the, human"
29000,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.109375,"a, in, the, that, was, of, at"
29001,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.109375,"sars-cov-2, was, and, the, lineage, b, of"
29002,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.109375,"a, the, on, natural, of, is, human"
29003,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.109375,"the, that, of, natural, sars-cov-2, is, or"
29004,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.109375,"that, of, pangolin, to, the, for, sars-cov-2"
29005,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.109375,"the, and, to, that, is, of, bat"
29006,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.109375,"have, that, the, in, bats, and, china"
29007,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.109375,"the, of, bats, natural, for, two, and"
29008,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.109375,"patient, was, in, that, the, to, of"
29009,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.109375,"the, has, in, to, that, not, of"
29010,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.109375,"the, of, bat, in, caves, viruses, can"
29011,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.109375,"wild, animals, in, the, wet, market, have"
29012,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.109375,"the, amino, acid, sars-cov-2, of, is, in"
29013,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.109375,"one, also, the, of, have, potential, to"
29014,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.109375,"the, of, and, that, to, humans, by"
29015,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.109375,"the, of, as, a, from, bats,, and"
29016,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.109375,"of, and, by, bat, a, species, the"
29017,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.109375,"the, by, from, a, and, to, of"
29018,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.109375,"other, sars-cov-2, to, pangolin, and, a, the"
29019,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.109375,"the, coronavirus, to, be, amino, acid, in"
29020,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.109375,"the, virus, has, a, of, to, that"
29021,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.109375,"a, intermediate, for, sars-cov-2, it, the, in"
29022,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.109375,"in, was, to, that, of, sars-cov-2, the"
29023,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.109375,"the, of, sars-cov-2, is, natural, or, that"
29024,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.109375,"that, of, with, are, the, for, sars-cov-2"
29025,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.109375,"several, recently, sars-cov-2, and, of, to, that"
29026,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.109375,"in, found, of, sequences, and, which, to"
29027,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.109375,"to, sars-cov-2, from, a, the, and, that"
29028,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.109375,"the, patient, was, to, that, in, of"
29029,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.109375,"to, that, the, complete, virus, bats, of"
29030,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.109375,"the, is, of, human, and, in, also"
29031,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.109375,"found, in, which, to, of, and, sequences"
29032,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.109375,"that, sars-cov-2, with, potentially, been, and, to"
29033,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.109375,"pangolin, to, sars-cov-2, the, that, for, of"
29034,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.109375,"the, that, are, with, of, sars-cov-2, for"
29035,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.109375,"in, viruses, and, sars-cov-2, with, that, the"
29036,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.109375,"in, the, and, are, to, that, these"
29037,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.109375,"viruses, are, bat, that, the, sars-cov-2, this"
29038,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.109375,"the, in, and, that, sars-cov-2, with, viruses"
29039,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.109375,"that, sars-cov-2, to, with, bat, as, the"
29040,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.109375,"of, the, are, as, those, in, pangolin"
29041,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.109375,"of, more, than, and, that, bats, for"
29042,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.109375,"a, pangolin, and, sars-cov-2, other, to, the"
29043,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.109375,"that, direct, of, bats, to, sars-cov-2, the"
29044,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.109375,"complete, that, the, virus, to, of, bats"
29045,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.109375,"a, the, recombination, of, virus, with, to"
29046,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.109375,"the, of, in, similar, to, yunnan, that"
29047,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.109375,"to, was, the, of, that, sars-cov-2, in"
29048,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.109375,"a, of, that, the, sars-cov-2,, in, naturally"
29049,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.109375,"at, the, amino, in, similar, to, sars-cov-2,"
29050,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.109375,"are, and, the, from, bats, to, in"
29051,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.109375,"the, of, is, closely, related, to, sars-"
29052,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.109375,"coronavirus, amino, acid, to, be, in, the"
29053,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.109375,"the, not, to, that, has, in, of"
29054,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.109375,"of, also, have, potential, the, to, one"
29055,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.109375,"to, closely, related, the, of, sars-, is"
29056,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.109375,"and, sars-cov-2, to, in, genetic, many, viruses"
29057,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.109375,"the, viruses, and, of, many, to, emergence"
29058,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.109375,"zoonotic, of, sars-cov-2, in, and, to, on"
29059,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.109243697,"and, from, in, were, found, to, closely, related, that, the, of, coronavirus, is"
29060,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.109243697,"in, the, of, from, found, that, to, were, coronavirus, is, closely, related, and"
29061,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.109090909,"a, that, from, bats, and, the"
29062,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.109090909,"in, to, sars-cov-2, human, and, a"
29063,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.109090909,"from, virus, natural, and, the, into"
29064,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.109090909,"the, of, have, and, animal, reservoirs"
29065,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.109090909,"be, to, bats, of, and, are"
29066,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.109090909,"of, and, the, to, reservoir, species"
29067,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.109090909,"one, or, more, of, bats, and"
29068,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.109090909,"sars-cov-2, and, to, which, in, bats"
29069,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.109090909,"and, may, have, occurred, the, from"
29070,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.109090909,"the, in, a, as, it, to"
29071,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.109090909,"the, is, to, a, of, it"
29072,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.109090909,"sars-cov-2, is, to, in, the, with"
29073,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.109090909,"the, of, sars-cov-2, to, a, with"
29074,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.109090909,"the, of, sars-cov-2, is, a, in"
29075,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.109090909,"the, is, it, with, to, of"
29076,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.109090909,"the, to, be, sars-cov-2, and, of"
29077,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.109090909,"is, in, a, naturally, occurring, to"
29078,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.109090909,"and, the, of, which, is, via"
29079,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.109090909,"of, sars-cov-2, to, which, the, in"
29080,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.109090909,"genetic, the, that, in, a, from"
29081,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.109090909,"the, is, sars-cov-2, a, virus, in"
29082,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.109090909,"the, of, to, that, human, and"
29083,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.109090909,"and, of, the, viruses, to, human"
29084,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.109090909,"with, bat, that, the, as, sars-cov-2"
29085,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.109090909,"virus, bat, of, and, as, on"
29086,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.109090909,"genome, the, covid-19, virus, and, showed"
29087,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.109090909,"the, of, mers-cov, to, bat, and"
29088,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.109090909,"the, have, animal, reservoirs, of, and"
29089,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.109090909,"have, that, the, and, to, humans"
29090,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.109090909,"in, a, of, that, the, as"
29091,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.109090909,"of, the, after, viruses, bats, reservoirs"
29092,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.109090909,"into, the, that, is, in, to"
29093,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.109090909,"the, a, an, host, as, to"
29094,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.109090909,"the, humans,, from, to, humans, for"
29095,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.109090909,"the, of, from, intermediate, hosts, for"
29096,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.109090909,"the, of, animal, market, that, in"
29097,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.109090909,"in, to, is, of, the, covid-19"
29098,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.109090909,"the, of, that, has, been, and"
29099,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.109090909,"and, the, of, bats, are, natural"
29100,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.109090909,"and, from, natural, the, virus, into"
29101,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.109090909,"at, the, in, from, is, to"
29102,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.109090909,"to, the, severe, respiratory, of, and"
29103,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.109090909,"sars-cov-2, is, and, bat, to, that"
29104,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.109090909,"bats, are, for, the, of, that"
29105,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.109090909,"to, humans,, the, from, for, humans"
29106,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.109090909,"that, was, and, in, at, a"
29107,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.109090909,"that, for, are, animals, in, with"
29108,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.109090909,"the, in, and, that, a, with"
29109,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.109090909,"sars-cov-2, be, of, the, and, to"
29110,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.109090909,"the, of, support, sars-cov-2, humans, in"
29111,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.109090909,"been, of, to, pangolins, the, sars-cov-2"
29112,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.109090909,"an, host, species, and, found, in"
29113,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.109090909,"a, to, the, natural, of, as"
29114,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.109090909,"was, that, the, wuhan, have, of"
29115,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.109090909,"the, of, not, that, changes, and"
29116,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.109090909,"at, the, nucleotide, and, from, ratg13"
29117,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.109090909,"are, that, sars-cov-2, to, from, viruses"
29118,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.109090909,"to, sars-cov-2, the, this, that, of"
29119,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.109090909,"to, that, the, of, are, sars-cov-2"
29120,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.109090909,"the, of, that, animal, market, in"
29121,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.109090909,"the, sars-cov-2, humans, in, support, of"
29122,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.109090909,"the, and, a, of, is, in"
29123,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.109090909,"in, two, and, to, sars-cov-2, at"
29124,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.109090909,"the, presence, in, of, an, sars-cov-2"
29125,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.109090909,"of, the, in, and, sars-cov-2, a"
29126,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.109090909,"only, of, cases, to, the, that"
29127,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.109090909,"a, that, the, to, in, sars-cov-2"
29128,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.109090909,"that, suggests, sars-cov-2, although, animals, in"
29129,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.109090909,"in, an, from, to, sars-cov-2, and"
29130,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.109090909,"in, an, to, that, sars-cov-2, was"
29131,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.109090909,"other, that, sars-cov-2, are, to, and"
29132,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.109090909,"sars-cov-2, were, be, infected, with, that"
29133,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.109090909,"as, a, the, in, it, to"
29134,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.109090909,"that, from, a, the, genetic, in"
29135,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.109090909,"in, the, it, to, that, a"
29136,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.109090909,"it, that, a, the, genome, from"
29137,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.109090909,"to, a, is, in, naturally, occurring"
29138,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.109090909,"to, the, of, most, a, event"
29139,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.109090909,"the, to, that, most, sars-cov-2, and"
29140,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.109090909,"a, and, that, the, with, as"
29141,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.109090909,"that, and, to, on, the, with"
29142,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.109090909,"the, a, that, to, bat, and"
29143,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.109090909,"bats, a, the, of, in, with"
29144,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.109090909,"the, of, which, that, to, this"
29145,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.109090909,"to, in, who, been, close, or"
29146,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.109090909,"the, in, of, to, this, also"
29147,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.109090909,"other, also, to, and, the, of"
29148,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.109090909,"the, and, horseshoe, from, is, to"
29149,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.109090909,"is, that, the, of, virus, from"
29150,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.109090909,"a, and, that, the, from, bats"
29151,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.109090909,"was, a, and, to, sars-cov-2, the"
29152,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.109090909,"and, a, sars-cov-2, is, the, to"
29153,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.109090909,"bat, coronavirus, to, which, the, genome"
29154,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.109090909,"of, the, spike, similar, to, can"
29155,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.109090909,"the, of, is, and, be, to"
29156,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.109090909,"of, sequences, and, which, have, to"
29157,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.109090909,"the, to, that, have, humans, and"
29158,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.109090909,"the, of, to, in, is, covid-19"
29159,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.109090909,"the, are, of, bats, in, and"
29160,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.109090909,"the, covid-19, to, and, was, but"
29161,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.109090909,"bats, of, and, to, zoonotic, that"
29162,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.109090909,"is, natural, on, to, the, for"
29163,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.109090909,"on, and, sars-cov, is, of, bat"
29164,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.109090909,"the, that, to, bat, viruses,, related"
29165,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.109090909,"that, have, the, was, wuhan, of"
29166,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.109090909,"the, that, in, animals, with, were"
29167,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.109090909,"bats, the, after, reservoirs, of, viruses"
29168,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.109090909,"to, sars-cov-2, of, the, has, been"
29169,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.109090909,"the, a, host, for, it, and"
29170,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.109090909,"the, by, was, a, and, to"
29171,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.109090909,"the, of, can, be, to, animal"
29172,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.109090909,"the, of, genome, is, to, bat"
29173,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.109090909,"the, analysis, to, which, cov,, and"
29174,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.109090909,"at, which, was, found, the, with"
29175,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.109090909,"that, sars-cov-2, with, bat, as, the"
29176,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.109090909,"analysis, of, that, the, bat, and"
29177,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.109090909,"the, genome, of, is, to, bat"
29178,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.109090909,"virus, is, sars-cov-2, the, sequence, of"
29179,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.109090909,"sars-cov, on, of, bat, is, and"
29180,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.109090909,"from, bats, to, humans, sars-cov-2, the"
29181,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.109090909,"from, the, closely, related, to, bats"
29182,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.109090909,"may, in, animal, and, the, or"
29183,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.109090909,"was, with, other, and, the, genome"
29184,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.109090909,"this, in, the, of, was, virus"
29185,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.109090909,"the, ace2, virus, in, this, covid-19"
29186,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.109090909,"virus, genome, the, covid-19, and, showed"
29187,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.109090909,"the, of, from, with, and, mutation"
29188,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.109090909,"of, the, isolated, in, from, and"
29189,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.109090909,"the, and, to, that, coronaviruses, are"
29190,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.109090909,"to, the, as, a, of, natural"
29191,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.109090909,"bats, the, a, of, sars-cov, and"
29192,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.109090909,"and, pangolin, coronaviruses, to, the, of"
29193,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.109090909,"the, to, that, highly, coronaviruses, of"
29194,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.109090909,"that, related, to, bat, viruses,, the"
29195,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.109090909,"the, to, as, of, bat, and"
29196,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.109090909,"that, the, and, to, wuhan, of"
29197,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.109090909,"sars-cov-2, zoonotic, to, in, ace2, protein"
29198,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.109090909,"revealed, the, of, genomes, and, two"
29199,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.109090909,"the, that, seafood, market, and, in"
29200,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.109090909,"the, and, which, of, is, via"
29201,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.109090909,"in, a, was, that, at, and"
29202,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.109090909,"the, of, in, from, that, intermediate"
29203,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.109090909,"that, a, of, the, most, likely"
29204,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.109090909,"the, in, that, likely, hosts, for"
29205,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.109090909,"that, pangolin, a, on, the, of"
29206,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.109090909,"the, coronavirus, sequence, in, of, s"
29207,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.109090909,"of, sars-, bats, to, intermediate, the"
29208,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.109090909,"and, sars-cov-2, in, to, bats, which"
29209,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.109090909,"sars-cov-2, that, and, is, to, bat"
29210,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.109090909,"that, a, bat, in, 96.2%, sars-cov-2"
29211,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.109090909,"of, genomes, the, revealed, two, and"
29212,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.109090909,"this, of, to, the, which, that"
29213,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.109090909,"a, of, the, it, is, to"
29214,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.109090909,"and, a, of, is, the, to"
29215,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.109090909,"the, of, that, in, a, to"
29216,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.109090909,"the, a, in, to, that, of"
29217,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.109090909,"cases, only, the, of, that, to"
29218,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.109090909,"et, was, the, to, of, bats"
29219,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.109090909,"sars-cov-2, from, a, of, the, and"
29220,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.109090909,"the, sars-cov-2, and, to, of, in"
29221,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.109090909,"the, of, and, viruses, in, for"
29222,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.109090909,"a, it, the, and, for, host"
29223,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.109090909,"from, and, sars-like, bats,, covs, with"
29224,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.109090909,"most, a, event, the, of, to"
29225,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.109090909,"the, is, in, that, to, into"
29226,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.109090909,"human, and, sars-cov-2, to, in, a"
29227,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.109090909,"the, and, of, that, to, human"
29228,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.109090909,"changes, and, that, not, the, of"
29229,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.109090909,"the, that, in, a, it, to"
29230,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.109090909,"bats, to, the, of, sars-, intermediate"
29231,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.109090909,"species, to, an, in, the, of"
29232,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.109090909,"in, the, of, sars-cov-2, with, and"
29233,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.109090909,"coronaviruses, in, with, sars-cov-2, the, and"
29234,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.109090909,"and, of, sars-cov-2, in, which, the"
29235,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.109090909,"sars-cov-2, a, bat, 96.2%, that, in"
29236,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.109090909,"found, in, horseshoe, that, of, sars-cov-2"
29237,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.109090909,"and, the, of, that, sars-cov-2, is"
29238,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.109090909,"in, et, al., (2020), and, to"
29239,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.109090909,"in, the, from, to, humans, and"
29240,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.109090909,"an, sars-cov-2, to, from, and, in"
29241,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.109090909,"to, sars-cov-2, in, the, ace2, of"
29242,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.109090909,"to, the, of, bats, and, sars-cov-2"
29243,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.109090909,"is, at, the, to, in, from"
29244,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.109090909,"nucleotide, and, from, the, ratg13, at"
29245,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.109090909,"the, is, to, and, from, horseshoe"
29246,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.109090909,"to, is, from, bats, and, the"
29247,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.109090909,"the, as, a, that, with, and"
29248,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.109090909,"the, animal, in, or, and, may"
29249,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.109090909,"on, the, that, with, and, to"
29250,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.109090909,"the, that, sars-cov-2, with, and, to"
29251,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.109090909,"in, the, that, a, sars-cov-2, to"
29252,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.109090909,"of, for, sars-cov-2, to, be, may"
29253,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.109090909,"a, as, the, to, an, host"
29254,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.109090909,"the, a, of, to, that, and"
29255,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.109090909,"the, of, to, a, that, evidence"
29256,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.109090909,"that, a, of, to, and, the"
29257,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.109090909,"in, the, of, from, that, intermediate"
29258,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.109090909,"the, that, a, genome, it, from"
29259,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.109090909,"the, virus, is, that, of, from"
29260,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.109090909,"the, of, that, sars-cov-2, a, genome"
29261,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.109090909,"is, sars-cov-2, a, the, virus, in"
29262,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.109090909,"one, of, more, and, bats, or"
29263,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.109090909,"are, in, of, the, bats, and"
29264,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.109090909,"or, of, and, in, cave, bats"
29265,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.109090909,"the, of, to, bat, as, and"
29266,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.109090909,"the, of, bat, species, as, to"
29267,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.109090909,"most, that, the, sars-cov-2, and, to"
29268,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.109090909,"that, and, sars-cov-2, to, the, in"
29269,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.109090909,"in, the, and, are, to, that"
29270,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.109090909,"to, other, and, the, were, in"
29271,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.109090909,"the, and, viruses, to, in, virus"
29272,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.109090909,"the, of, and, bat, in, to"
29273,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.109090909,"of, to, an, in, species, the"
29274,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.109090909,"the, and, in, to, bat, of"
29275,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.109090909,"the, species, to, as, of, bat"
29276,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.109090909,"that, the, covid-19, in, to, of"
29277,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.109090909,"a, of, in, that, for, with, the, to, less, virus, closely, related"
29278,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.109090909,"the, genome, which, to, coronavirus, bat"
29279,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.109090909,"at, two, sars-cov-2, in, and, to"
29280,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.109090909,"to, sars-cov-2, a, and, was, the"
29281,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.109090909,"the, genome, and, other, was, with"
29282,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.109090909,"sars-cov-2, to, in, the, with, which"
29283,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.109090909,"similar, to, the, of, and, that"
29284,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.109090909,"are, to, that, of, and, rbds"
29285,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.109090909,"the, rbd, to, ace2, that, of"
29286,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.109090909,"the, coronaviruses, and, in, with, sars-cov-2"
29287,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.109090909,"sars-cov-2, to, in, the, with, bat"
29288,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.109090909,"a, was, the, and, to, by"
29289,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.109090909,"the, of, to, a, closely, related, with, that, in, for, virus, less"
29290,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.109090909,"the, and, other, to, were, in"
29291,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.109090909,"the, of, is, to, and, a"
29292,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.109090909,"that, the, seafood, market, in, and"
29293,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.109090909,"that, the, with, at, of, and"
29294,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.109090909,"to, on, the, natural, is, for"
29295,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.109090909,"the, natural, of, and, viruses, in"
29296,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.109090909,"sars-cov-2, in, a, that, the, with"
29297,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.109090909,"that, likely, the, of, is, to"
29298,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.109090909,"that, the, in, to, from, a"
29299,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.109090909,"that, the, similarity, sars-cov-2, pangolin, is"
29300,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.109090909,"that, sars-cov-2, to, pangolin, the, of"
29301,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.109090909,"in, the, an, presence, of, sars-cov-2"
29302,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.109090909,"that, was, an, sars-cov-2, to, in"
29303,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.109090909,"also, the, of, in, this, to"
29304,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.109090909,"of, the, also, that, to, virus"
29305,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.109090909,"the, that, also, of, sars-cov-2, an"
29306,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.109090909,"to, that, the, of, pangolins, sars-cov-2"
29307,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.109090909,"of, the, from, with, and, mutation"
29308,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.109090909,"however,, sars-cov-2, the, and, coronaviruses, of"
29309,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.109090909,"the, of, coronaviruses, however,, and, sars-cov-2"
29310,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.109090909,"to, who, in, been, or, close"
29311,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.109090909,"but, to, the, covid-19, and, was"
29312,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.109090909,"that, a, one, to, and, the"
29313,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.109090909,"ace2, this, virus, the, covid-19, in"
29314,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.109090909,"analysis, the, to, which, cov,, and"
29315,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.109090909,"the, of, that, wuhan, to, and"
29316,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.109090909,"that, the, of, covid-19, in, to"
29317,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.109090909,"bat, that, the, of, and, analysis"
29318,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.109090909,"the, to, of, severe, and, respiratory"
29319,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.109090909,"the, of, and, similar, to, that"
29320,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.109090909,"that, bats, the, similar, to, a"
29321,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.109090909,"the, for, viruses, in, and, of"
29322,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.109090909,"of, viruses, in, natural, and, the"
29323,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.109090909,"in, that, the, between, and, of"
29324,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.109090909,"that, the, with, in, animals, were"
29325,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.109090909,"to, the, that, has, been, this"
29326,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.109090909,"by, from, in, china, the, is"
29327,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.109090909,"or, of, bats, in, cave, and"
29328,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.109090909,"an, host, and, found, in, species"
29329,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.109090909,"bats, of, and, are, to, be"
29330,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.109090909,"on, virus, and, bat, as, of"
29331,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.109090909,"et, al., are, the, to, these, by, may, be, in, of, and"
29332,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.109090909,"of, a, and, the, market, in"
29333,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.109090909,"of, the, isolated, from, in, and"
29334,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.109090909,"is, origin, the, been, from, and"
29335,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.109090909,"and, have, the, origin, sars-cov-2, guangdong"
29336,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.109090909,"the, sars-cov-2, of, sequence, virus, is"
29337,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.109090909,"have, occurred, the, and, may, from"
29338,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.109090909,"may, have, and, pangolins, the, intermediate"
29339,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.109090909,"most, a, likely, the, is, to"
29340,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.109090909,"of, and, species, to, the, reservoir"
29341,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.109090909,"the, and, mers-cov, to, bat, of"
29342,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.109090909,"the, from, bats,, and, a, dromedary"
29343,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.109090909,"the, of, to, that, also, virus"
29344,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.109090909,"the, of, a, that, most, likely"
29345,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.109090909,"suggest, that, the, of, and, origin"
29346,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.109090909,"it, is, that, of, sars-cov-2, the"
29347,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.109090909,"the, of, an, that, sars-cov-2, also"
29348,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.109090909,"to, sars-cov-2, has, the, origin, of"
29349,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.109090909,"on, from, in, the, bat, based"
29350,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.109090909,"that, horseshoe, found, in, of, sars-cov-2"
29351,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.109090909,"rbds, of, and, are, to, that"
29352,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.109090909,"the, to, this, that, has, been"
29353,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.109090909,"the, been, from, origin, is, and"
29354,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.109090909,"the, sars-cov-2, which, to, of, in"
29355,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.109090909,"the, be, by, these, of, are, to, and, in, et, al., may"
29356,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.109090909,"from, to, closely, related, bats, the"
29357,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.109090909,"was, et, to, bats, the, of"
29358,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.109090909,"the, is, by, from, in, china"
29359,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.109090909,"similar, to, the, bats, that, a"
29360,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.109090909,"the, viruses, and, of, to, human"
29361,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.109090909,"to, sars-cov-2, is, a, and, the"
29362,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.109090909,"the, of, and, which, in, sars-cov-2"
29363,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.109090909,"of, and, have, sequences, which, to"
29364,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.109090909,"et, al., (2020), in, to, and"
29365,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.109090909,"to, and, of, similar, related, in"
29366,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.109090909,"in, that, are, animals, with, for"
29367,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.109090909,"in, although, suggests, that, sars-cov-2, animals"
29368,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.109090909,"that, pangolins, hosts, for, are, sars-cov-2"
29369,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.109090909,"the, sars-cov-2, been, to, pangolins, of"
29370,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.109090909,"the, to, and, that, a, one"
29371,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.109090909,"intermediate, and, pangolins, may, have, the"
29372,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.109090909,"in, the, a, that, and, with"
29373,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.109090909,"in, the, and, a, of, sars-cov-2"
29374,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.109090909,"methods, that, the, of, and, sars-cov-2"
29375,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.109090909,"and, to, the, viruses, that, in"
29376,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.109090909,"we, sars-cov-2, the, believe, that, is"
29377,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.109090909,"viruses, to, the, in, and, that"
29378,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.109090909,"the, in, is, to, with, sars-cov-2"
29379,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.109090909,"in, the, is, to, sars-cov-2, with"
29380,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.109090909,"in, with, which, to, sars-cov-2, the"
29381,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.109090909,"to, in, with, sars-cov-2, the, bat"
29382,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.109090909,"in, the, that, likely, hosts, for"
29383,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.109090909,"sars-cov-2, in, the, this, that, for"
29384,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.109090909,"pangolin, similarity, sars-cov-2, the, that, is"
29385,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.109090909,"the, sars-cov-2, have, origin, guangdong, and"
29386,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.109090909,"the, pangolins, of, to, that, sars-cov-2"
29387,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.109090909,"and, suggest, that, origin, of, the"
29388,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.109090909,"of, the, methods, and, that, sars-cov-2"
29389,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.109090909,"based, on, the, bat, in, from"
29390,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.109090909,"the, a, that, are, to, and"
29391,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.109090909,"are, that, other, sars-cov-2, to, and"
29392,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.109090909,"other, also, the, of, and, to"
29393,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.109090909,"on, the, of, a, pangolin, that"
29394,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.109090909,"pangolin, to, sars-cov-2, the, that, of"
29395,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.109090909,"a, of, the, to, with, sars-cov-2"
29396,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.109090909,"to, sars-cov-2, of, the, and, with"
29397,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.109090909,"the, dromedary, a, from, bats,, and"
29398,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.109090909,"sars-cov, and, a, the, bats, of"
29399,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.109090909,"with, sars-like, covs, from, bats,, and"
29400,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.109090909,"that, the, of, and, in, between"
29401,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.109090909,"to, the, of, sars-cov-2, origin, has"
29402,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.109090909,"of, sars-cov-2, to, be, origin, that"
29403,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.109090909,"the, that, sars-cov-2, is, of, they"
29404,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.109090909,"a, of, the, in, is, sars-cov-2"
29405,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.109090909,"in, a, for, sars-cov-2, be, that"
29406,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.109090909,"of, the, it, is, to, with"
29407,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.109090909,"and, of, is, an, the, to"
29408,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.109090909,"that, be, infected, with, sars-cov-2, were"
29409,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.109090909,"of, sars-cov-2, to, may, be, for"
29410,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.109090909,"to, that, sars-cov-2, be, origin, of"
29411,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.109090909,"be, a, in, that, sars-cov-2, for"
29412,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.109090909,"that, zoonotic, and, bats, of, to"
29413,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.109090909,"the, was, found, at, which, with"
29414,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.109090909,"that, of, to, in, sars-cov-2, the"
29415,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.109090909,"was, in, that, the, to, of"
29416,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.109090909,"the, rmyn02, in, to, that, of"
29417,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.109090909,"similar, to, can, the, spike, of"
29418,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.109090909,"sequence, in, the, s, of, coronavirus"
29419,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.109090909,"to, in, the, rbd, is, of"
29420,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.109090909,"of, the, that, highly, to, coronaviruses"
29421,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.109090909,"rmyn02, in, to, that, of, the"
29422,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.109090909,"and, of, is, to, that, bat"
29423,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.109090909,"in, related, of, and, similar, to"
29424,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.109090909,"sars-cov-2, to, ace2, protein, in, zoonotic"
29425,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.109090909,"the, virus, and, viruses, to, in"
29426,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.109090909,"coronaviruses, and, to, the, of, pangolin"
29427,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.108910891,"the, a, for, of, as, reservoir, with, is, on, and, palm"
29428,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.108910891,"bats, are, of, and, a, which, related, to, that, in, as"
29429,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.108910891,"evidence, that, bats, are, the, of, and, viruses, in, china, markets"
29430,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.108910891,"a, for, the, on, palm, as, reservoir, of, is, and, with"
29431,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.108910891,"evidence, that, bats, in, the, china, and, of, markets, are, viruses"
29432,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.108910891,"and, of, to, are, as, a, related, bats, that, in, which"
29433,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.108695652,"in, the, of, sars-cov-2,, pangolins"
29434,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.108695652,"pangolin, many, in, and, a"
29435,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.108695652,"closely, related, to, genetic, bat"
29436,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.108695652,"the, of, into, humans, from"
29437,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.108695652,"the, natural, virus, and, humans"
29438,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.108695652,"the, of, natural, human, and"
29439,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.108695652,"the, bats, as, two, from"
29440,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.108695652,"the, of, to, and, species"
29441,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.108695652,"of, and, sars-cov-2, which, to"
29442,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.108695652,"of, more, than, to, sars-cov"
29443,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.108695652,"and, more, of, sars-cov-2, to"
29444,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.108695652,"of, and, china,, species,, in"
29445,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.108695652,"the, genetic, and, sarbecovirus, to"
29446,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.108695652,"human, to, infection, and, spillover"
29447,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.108695652,"virus, from, to, the, spillover"
29448,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.108695652,"and, resulted, the, emergence, of"
29449,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.108695652,"of, sars-cov-2, have, been, origin"
29450,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.108695652,"that, sars-cov-2, be, origin, of"
29451,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.108695652,"of, the, have, been, that"
29452,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.108695652,"a, between, sars-cov-2, spike, and"
29453,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.108695652,"the, by, a, that, in"
29454,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.108695652,"the, was, by, a, laboratory"
29455,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.108695652,"the, many, and, that, of"
29456,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.108695652,"that, the, of, and, viruses"
29457,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.108695652,"the, that, with, sars-cov-2, as"
29458,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.108695652,"the, to, have, that, with"
29459,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.108695652,"bat, the, with, sars-cov-2, that"
29460,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.108695652,"and, a, of, the, viruses"
29461,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.108695652,"was, the, 96.2%, identity, genome"
29462,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.108695652,"phylogenetic, analysis, of, that, and"
29463,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.108695652,"that, in, pangolin, and, of"
29464,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.108695652,"of, with, and, sars-cov-2, or"
29465,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.108695652,"the, in, sars-cov-2, with, sequence"
29466,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.108695652,"of, reservoirs, and, to, the"
29467,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.108695652,"has, the, in, of, as"
29468,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.108695652,"that, the, of, in, a"
29469,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.108695652,"as, the, of, coronaviruses,, most"
29470,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.108695652,"of, the, sars-cov-2,, in, pangolins"
29471,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.108695652,"the, in, were, as, of"
29472,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.108695652,"the, to, sars-cov-2, from, of"
29473,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.108695652,"in, the, of, has, as"
29474,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.108695652,"the, wuhan, of, had, before"
29475,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.108695652,"on, that, is, likely, of"
29476,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.108695652,"in, of, were, to, the"
29477,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.108695652,"this, the, in, that, likely"
29478,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.108695652,"a, and, in, province,, china"
29479,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.108695652,"a, of, be, the, coronavirus"
29480,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.108695652,"a, and, to, of, the"
29481,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.108695652,"that, the, bats, and, of"
29482,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.108695652,"species, bats, and, by, the"
29483,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.108695652,"and, may, be, hosts, the"
29484,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.108695652,"transmission, from, as, the, for"
29485,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.108695652,"the, sequenced, at, of, with"
29486,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.108695652,"and, to, of, the, other"
29487,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.108695652,"the, of, and, which, to"
29488,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.108695652,"other, to, in, the, and"
29489,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.108695652,"was, the, in, china, animals"
29490,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.108695652,"of, that, the, is, bat"
29491,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.108695652,"in, the, are, middle, and"
29492,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.108695652,"the, of, to, sars-cov-2, and"
29493,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.108695652,"and, are, to, sars-cov-2, the"
29494,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.108695652,"are, to, sars-cov-2, the, and"
29495,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.108695652,"can, of, and, the, bats"
29496,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.108695652,"and, of, sars-cov-2, the, to"
29497,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.108695652,"of, sars-cov-2, from, bats, pangolins"
29498,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.108695652,"the, of, in, from, this"
29499,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.108695652,"is, of, sars-cov-2, the, through"
29500,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.108695652,"this, the, in, bats, sars-cov-2"
29501,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.108695652,"a, and, that, the, in"
29502,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.108695652,"that, a, by, the, in"
29503,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.108695652,"in, the, that, and, a"
29504,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.108695652,"the, and, in, one, by"
29505,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.108695652,"and, a, in, which, the"
29506,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.108695652,"in, transmitted, to, an, animal"
29507,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.108695652,"a, that, the, sars-cov-2, to"
29508,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.108695652,"from, a, to, the, that"
29509,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.108695652,"through, that, the, and, sars-cov-2"
29510,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.108695652,"sars-cov-2, natural, that, through, the"
29511,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.108695652,"the, that, and, not, from"
29512,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.108695652,"studies, that, the, from, and"
29513,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.108695652,"that, the, and, wuhan, of"
29514,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.108695652,"that, was, the, of, sars-cov-2"
29515,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.108695652,"sars-cov-2, from, bats, pangolins, of"
29516,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.108695652,"the, of, that, to, this"
29517,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.108695652,"that, the, of, a, to"
29518,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.108695652,"bat, to, sars-cov-2, at, the"
29519,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.108695652,"of, to, a, from, bat"
29520,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.108695652,"from, of, the, into, humans"
29521,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.108695652,"the, of, sars-cov-2, for, humans"
29522,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.108695652,"the, of, from, explanation, sars-cov-2"
29523,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.108695652,"at, the, sars-cov-2, probable, for"
29524,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.108695652,"that, the, sars-cov-2, and, to"
29525,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.108695652,"in, the, case, of, and"
29526,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.108695652,"the, presence, of, and, in"
29527,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.108695652,"he, of, from, the, huanan"
29528,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.108695652,"the, was, and, that, sars-cov-2"
29529,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.108695652,"in, the, that, sars-cov-2, animal"
29530,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.108695652,"from, in, to, humans, and"
29531,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.108695652,"to, of, sars-cov-2, least, and"
29532,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.108695652,"in, and, to, humans, of"
29533,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.108695652,"the, zoonotic, as, in, and"
29534,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.108695652,"a, in, the, that, sars-cov-2"
29535,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.108695652,"of, evidence, supports, the, or"
29536,"Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.108695652,"presence, of, live, animal, in"
29537,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.108695652,"there, is, that, sars-cov-2, in"
29538,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.108695652,"it, is, that, sars-cov-2, laboratory"
29539,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.108695652,"that, sars-cov-2, is, to, from"
29540,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.108695652,"there, that, sars-cov-2, is, in"
29541,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.108695652,"that, sars-cov-2, with, as, the"
29542,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.108695652,"that, be, the, sars-cov-2, on"
29543,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.108695652,"the, genome, that, from, a"
29544,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.108695652,"that, the, in, to, humans"
29545,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.108695652,"that, as, to, in, humans"
29546,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.108695652,"in, the, of, a, at, found, that, virus, were, and"
29547,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.108695652,"that, is, an, to, a"
29548,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.108695652,"on, the, bat, virus, and"
29549,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.108695652,"of, to, species, infect, and"
29550,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.108695652,"the, of, case, and, in"
29551,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.108695652,"the, sequence, that, was, to"
29552,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.108695652,"the, that, a, coronavirus, covid-19"
29553,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.108695652,"the, in, market, to, and"
29554,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.108695652,"to, the, of, a, high"
29555,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.108695652,"to, of, a, with, around"
29556,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.108695652,"to, virus, had, been, the"
29557,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.108695652,"the, of, than, to, in"
29558,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.108695652,"the, that, of, virus, to"
29559,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.108695652,"to, from, and, the, of"
29560,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.108695652,"that, the, from, to, and"
29561,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.108695652,"the, horseshoe, to, of, and"
29562,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.108695652,"to, the, of, from, virus"
29563,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.108695652,"to, from, and, the, sars-cov-2"
29564,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.108695652,"the, virus, to, as, is"
29565,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.108695652,"intermediate, bats, and, was, the"
29566,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.108695652,"of, the, that, a, virus"
29567,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Bats have been reported as being the rich source of 

coronaviruses",0.108695652,"coronaviruses, the, bats, of, as"
29568,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.108695652,"a, with, to, sars-cov-2, the"
29569,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.108695652,"a, to, with, sars-cov-2, the"
29570,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.108695652,"a, similarity, sars-cov-2, the, to"
29571,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.108695652,"the, to, of, and, from"
29572,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.108695652,"to, sars-cov-2, from, and, the"
29573,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.108695652,"the, that, a, virus, originated"
29574,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.108695652,"the, of, to, bat, and"
29575,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.108695652,"and, sars-cov-2, to, of, which"
29576,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.108695652,"have, on, which, is, of"
29577,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.108695652,"virus, the, was, to, and"
29578,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.108695652,"a, in, the, from, possibly"
29579,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.108695652,"that, bats, the, to, a"
29580,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.108695652,"the, of, to, may, through"
29581,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.108695652,"virus, animals, to, the, is"
29582,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.108695652,"the, of, and, has, in"
29583,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.108695652,"of, the, is, naturally, virus"
29584,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.108695652,"and, natural, the, virus, humans"
29585,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.108695652,"the, to, that, in, animals"
29586,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.108695652,"the, is, that, and, in"
29587,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.108695652,"of, the, in, huanan, seafood"
29588,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.108695652,"of, be, the, that, bats"
29589,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.108695652,"the, of, that, may, to"
29590,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.108695652,"be, the, host, and, intermediate"
29591,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.108695652,"as, the, for, of, and"
29592,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.108695652,"the, is, sars-cov-2, to, related"
29593,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.108695652,"to, that, the, is, be"
29594,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.108695652,"sars-cov-2, is, to, the, bat"
29595,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.108695652,"that, the, virus, in, market"
29596,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.108695652,"the, was, seafood, market, wuhan"
29597,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.108695652,"in, the, of, were, as"
29598,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.108695652,"the, was, in, animals, china"
29599,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.108695652,"the, was, in, that, as"
29600,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.108695652,"be, a, of, coronavirus, the"
29601,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.108695652,"that, the, bats, be, of"
29602,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.108695652,"with, bats, be, the, of"
29603,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.108695652,"to, the, of, bat, human"
29604,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.108695652,"the, of, sars-cov-2, to, human"
29605,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.108695652,"been, of, to, the, sars-cov-2"
29606,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.108695652,"sars-cov-2, to, the, for, and"
29607,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.108695652,"a, and, to, which, the"
29608,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.108695652,"sars-cov, to, of, more, than"
29609,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.108695652,"of, the, is, similar, entire"
29610,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.108695652,"the, was, found, to, be"
29611,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.108695652,"to, and, infection, human, spillover"
29612,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.108695652,"to, humans, can, and, in"
29613,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.108695652,"the, sarbecovirus, and, genetic, to"
29614,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.108695652,"of, and, to, the, new"
29615,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.108695652,"have, that, the, of, and"
29616,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.108695652,"that, sars-cov-2, may, have, to"
29617,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.108695652,"to, that, may, have, sars-cov-2"
29618,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.108695652,"the, of, from, nearly, a"
29619,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.108695652,"the, protein, of, pangolin, as"
29620,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.108695652,"on, of, that, is, likely"
29621,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.108695652,"most, likely, of, bats, and"
29622,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.108695652,"that, a, is, to, an"
29623,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.108695652,"to, the, from, virus, spillover"
29624,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.108695652,"animals, to, is, the, virus"
29625,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.108695652,"the, is, a, from, for"
29626,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.108695652,"a, virus, to, the, for"
29627,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.108695652,"sars-cov-2, the, isolated, from, bat"
29628,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.108695652,"all, sars-cov-2, the, related, coronaviruses"
29629,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.108695652,"bat, the, are, all, sars-cov-2"
29630,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.108695652,"in, the, middle, are, and"
29631,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.108695652,"the, in, to, and, market"
29632,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.108695652,"virus, into, infected, to, the"
29633,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.108695652,"from, in, the, virus, and"
29634,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.108695652,"the, sars-cov-2, is, that, another"
29635,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.108695652,"and, sars-cov-2, to, of, more"
29636,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.108695652,"of, that, and, sars-cov-2, is"
29637,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.108695652,"of, and, to, is, that"
29638,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.108695652,"sars-cov-2, and, an, animal, humans"
29639,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.108695652,"is, that, sars-cov-2, to, through"
29640,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.108695652,"the, of, virus, bat, strain"
29641,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.108695652,"the, of, covid-19, with, in"
29642,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.108695652,"covid-19, the, in, december, 2019"
29643,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.108695652,"of, be, the, with, bats"
29644,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.108695652,"to, the, genome, bats, be"
29645,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.108695652,"the, in, zoonotic, as, and"
29646,"Bats have been reported as being the rich source of 

coronaviruses","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.108695652,"bats, as, the, of, coronaviruses"
29647,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.108695652,"to, the, of, sars-cov-2, is"
29648,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.108695652,"of, sars-cov-2, to, coronavirus, that"
29649,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.108695652,"the, from, as, to, very"
29650,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.108695652,"and, bat, to, the, that"
29651,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.108695652,"and, that, not, from, the"
29652,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.108695652,"the, that, a, genome, from"
29653,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.108695652,"the, from, and, sars-cov-2, genome"
29654,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.108695652,"genome, that, and, sars-cov-2, a"
29655,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.108695652,"the, that, sars-cov-2, a, genome"
29656,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.108695652,"sars-cov-2, in, receptor, to, human"
29657,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.108695652,"studies, and, that, from, the"
29658,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.108695652,"humans, from, in, and, to"
29659,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.108695652,"the, to, that, and, from"
29660,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.108695652,"who, that, a, was, and"
29661,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.108695652,"the, of, identical, to, that"
29662,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.108695652,"in, yunnan, of, sars-cov-2, the"
29663,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.108695652,"sars-cov-2, may, in, a, that"
29664,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.108695652,"the, analysis, of, that, sars-cov-2"
29665,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.108695652,"sars-cov, and, sars-cov-2, together, with"
29666,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.108695652,"he, of, the, huanan, from"
29667,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.108695652,"of, revealed, that, the, for"
29668,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.108695652,"results, that, the, for, sars-cov-2"
29669,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.108695652,"et, al., the, of, to"
29670,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.108695652,"of, the, that, which, was"
29671,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.108695652,"study, suggested, the, of, intermediate"
29672,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.108695652,"most, likely, the, is, to"
29673,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.108695652,"a, the, sars-cov-2, from, research"
29674,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.108695652,"the, in, a, to, of"
29675,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.108695652,"genome, of, the, in, with"
29676,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.108695652,"in, the, of, that, at, was, similar, to, a, coronavirus"
29677,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.108695652,"the, of, that, a, may"
29678,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.108695652,"the, of, a, that, these"
29679,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.108695652,"a, of, the, that, suggest"
29680,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.108695652,"suggest, that, the, of, may"
29681,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.108695652,"the, of, hypothesis, that, sars-cov-2"
29682,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.108695652,"that, a, of, the, sars-cov-2"
29683,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.108695652,"the, covid-19, in, december, 2019"
29684,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.108695652,"have, in, to, the, is"
29685,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.108695652,"linked, the, of, to, and"
29686,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.108695652,"the, of, in, from, was"
29687,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.108695652,"a, of, in, the, horseshoe"
29688,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.108695652,"of, at, the, that, animal"
29689,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.108695652,"between, sars-cov-2, spike, and, a"
29690,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.108695652,"and, pangolin, in, a, many"
29691,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.108695652,"the, and, of, that, many"
29692,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.108695652,"the, of, that, a, pangolin"
29693,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.108695652,"in, furin, cleavage, sites, coronaviruses"
29694,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.108695652,"in, the, for, of, natural"
29695,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.108695652,"the, a, of, from, and"
29696,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.108695652,"the, of, sars-cov-2, natural, a"
29697,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.108695652,"the, to, that, sequence, was"
29698,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.108695652,"was, a, laboratory, by, the"
29699,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.108695652,"the, than, to, human, a"
29700,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.108695652,"was, by, a, to, the"
29701,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.108695652,"and, linked, to, the, of"
29702,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.108695652,"have, the, of, to, human"
29703,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.108695652,"in, of, the, has, and"
29704,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.108695652,"been, a, of, and, the"
29705,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.108695652,"found, that, are, also, to"
29706,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.108695652,"the, sars-cov-2, and, for, to"
29707,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.108695652,"in, the, of, sars-cov-2, to"
29708,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.108695652,"the, two, as, from, bats"
29709,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.108695652,"the, two, of, were, with"
29710,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.108695652,"natural, and, the, for, of"
29711,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.108695652,"the, most, as, of, coronaviruses,"
29712,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.108695652,"the, of, to, a, high"
29713,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.108695652,"a, contact, to, the, most"
29714,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.108695652,"wuhan, the, of, had, before"
29715,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.108695652,"is, that, the, covid-19, sars-cov-2"
29716,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.108695652,"to, the, had, been, virus"
29717,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.108695652,"the, to, human, than, a"
29718,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.108695652,"the, genome, sars-cov-2, and, from"
29719,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.108695652,"sars-cov-2, the, with, of, and"
29720,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.108695652,"of, the, been, origin, is"
29721,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.108695652,"that, has, the, origin, of"
29722,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.108695652,"and, phylogenetic, analysis, that, of"
29723,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.108695652,"is, and, that, of, sars-cov-2"
29724,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.108695652,"is, sars-cov-2, the, sequence, of"
29725,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.108695652,"the, of, et, al., to"
29726,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.108695652,"sars-cov-2, has, and, in, an"
29727,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.108695652,"the, of, were, to, in"
29728,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.108695652,"of, the, in, to, were"
29729,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.108695652,"the, from, sars-cov-2, to, and"
29730,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.108695652,"bat, and, the, 2, with"
29731,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.108695652,"the, sars-cov-2, of, et, al.,"
29732,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.108695652,"with, the, sars-cov-2, in, sequence"
29733,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.108695652,"furin, cleavage, sites, in, coronaviruses"
29734,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.108695652,"the, and, by, one, in"
29735,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.108695652,"that, sars-cov-2, may, in, or"
29736,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.108695652,"the, residues, in, sars-cov-2, and"
29737,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.108695652,"may, be, the, hosts, and"
29738,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.108695652,"the, for, of, sars-cov-2, humans"
29739,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.108695652,"infect, species, of, to, and"
29740,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.108695652,"may, the, of, through, to"
29741,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.108695652,"the, from, very, to, as"
29742,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.108695652,"a, to, that, the, of"
29743,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.108695652,"that, was, and, who, a"
29744,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.108695652,"huanan, seafood, in, the, of"
29745,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.108695652,"the, known, to, in, of"
29746,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.108695652,"the, from, in, of, this"
29747,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.108695652,"the, was, in, from, of"
29748,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.108695652,"of, sequences, was, from, in"
29749,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan",0.108695652,"in, live, animal, presence, of"
29750,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.108695652,"sars-cov-2, is, related, to, the"
29751,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.108695652,"a, of, sars-cov-2, the, in"
29752,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.108695652,"sars-cov-2, the, of, virus, to"
29753,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.108695652,"and, most, likely, bats, of"
29754,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.108695652,"the, are, in, of, one, horseshoe, most, likely, bats, and"
29755,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.108695652,"coronaviruses, sars-cov-2, the, including, of"
29756,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.108695652,"for, the, as, of, and"
29757,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.108695652,"least, of, sars-cov-2, and, to"
29758,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.108695652,"the, to, of, and, horseshoe"
29759,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.108695652,"to, the, most, of, and"
29760,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.108695652,"sars-cov-2, to, likely, the, bat"
29761,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.108695652,"closely, related, to, and, the"
29762,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.108695652,"sars-cov-2, that, to, the, most"
29763,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.108695652,"in, china, the, bat, and"
29764,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.108695652,"in, the, to, sars-cov-2, that"
29765,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.108695652,"the, in, to, of, and"
29766,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.108695652,"and, the, of, bat, in"
29767,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.108695652,"and, in, to, the, of"
29768,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.108695652,"and, in, china,, of, species,"
29769,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.108695652,"the, viruses, are, by, of"
29770,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.108695652,"the, of, and, are, similar"
29771,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.108695652,"are, the, similar, a, bat"
29772,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.108695652,"of, to, with, a, around"
29773,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.108695652,"to, sars-cov-2,, have, a, which"
29774,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.108695652,"at, to, bat, the, sars-cov-2"
29775,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.108695652,"the, similarity, sars-cov-2, bat, is"
29776,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.108695652,"sars-cov-2, genome, similar, to, the"
29777,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.108695652,"the, of, sars-cov-2, to, by"
29778,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.108695652,"of, viruses, are, by, the"
29779,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.108695652,"is, and, that, of, to"
29780,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.108695652,"of, and, similar, are, the"
29781,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.108695652,"is, similar, 97.4%, the, of"
29782,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.108695652,"have, the, of, human, to"
29783,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","This suggests that the BANAL series may be able to directly infect  

humans.",0.108695652,"that, may, be, to, the"
29784,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.108695652,"the, to, closely, related, and"
29785,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.108695652,"to, sars-cov-2,, which, have, a"
29786,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.108695652,"the, at, and, less, to"
29787,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.108695652,"sars-cov-2, the, and, cleavage, of"
29788,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.108695652,"closely, related, to, bat, genetic"
29789,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.108695652,"the, virus, is, to, of"
29790,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.108695652,"to, is, virus, the, as"
29791,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.108695652,"of, the, virus, bat, strain"
29792,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.108695652,"to, the, most, of, is"
29793,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.108695652,"the, sars-cov-2, to, is, most"
29794,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.108695652,"the, entire, of, is, similar"
29795,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.108695652,"is, similar, the, of, viral"
29796,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.108695652,"in, the, are, with, other"
29797,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.108695652,"that, the, sars-cov-2, is, it"
29798,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.108695652,"is, the, that, in, and"
29799,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.108695652,"that, sars-cov-2, through, and, the"
29800,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.108695652,"is, that, the, sars-cov-2, covid-19"
29801,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.108695652,"that, sars-cov-2, it, first, in"
29802,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.108695652,"sequenced, at, the, of, with"
29803,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.108695652,"seafood, market, wuhan, the, was"
29804,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.108695652,"a, coronavirus, in, the, that, was, similar, to, of, at"
29805,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.108695652,"a, at, the, of, and, in, found, virus, that, were"
29806,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.108695652,"and, samples, at, the, that, was, of, in, from, a"
29807,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.108695652,"the, most, likely, are, one, of, horseshoe, bats, in, and"
29808,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.108695652,"to, the, of, zoonotic, a"
29809,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.108695652,"that, the, at, and, to"
29810,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.108695652,"the, in, is, and, associated"
29811,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.108695652,"in, the, of, was, a, at, that, samples, from, and"
29812,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.108695652,"that, sars-cov-2, through, natural, the"
29813,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.108695652,"the, virus, into, infected, to"
29814,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.108695652,"to, the, most, a, contact"
29815,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.108695652,"the, to, that, most, sars-cov-2"
29816,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.108695652,"that, sars-cov-2, a, to, wildlife"
29817,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.108695652,"that, found, in, were, asian"
29818,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.108695652,"the, of, to, and, reservoirs"
29819,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.108695652,"a, the, and, to, which"
29820,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.108695652,"the, and, of, new, to"
29821,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.108695652,"in, the, of, which, to"
29822,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.108695652,"a, to, in, the, which"
29823,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.108695652,"in, of, and, which, to"
29824,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.108695652,"humans, and, sars-cov-2, an, animal"
29825,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.108695652,"in, sars-cov-2, has, and, an"
29826,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.108695652,"that, the, in, with, a"
29827,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.108695652,"sars-cov-2, bat, the, that, in"
29828,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.108695652,"in, the, sars-cov-2, that, virus"
29829,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.108695652,"is, that, sars-cov-2, the, another"
29830,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.108695652,"that, it, sars-cov-2, is, laboratory"
29831,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.108695652,"the, of, is, to, that"
29832,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.108695652,"to, the, that, a, from"
29833,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.108695652,"a, in, to, which, the"
29834,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.108695652,"the, of, that, it, is"
29835,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.108695652,"the, sars-cov-2, through, of, is"
29836,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.108695652,"the, that, sars-cov-2, to, also"
29837,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.108695652,"of, sars-cov-2, and, with, or"
29838,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.108695652,"the, explanation, of, sars-cov-2, from"
29839,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.108695652,"of, the, nearly, from, a"
29840,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.108695652,"a, of, from, coronaviruses, sars-cov-2"
29841,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.108695652,"all, sars-cov-2, related, coronaviruses, the"
29842,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.108695652,"the, cleavage, of, and, sars-cov-2"
29843,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.108695652,"the, covid-19, coronavirus, that, a"
29844,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.108695652,"a, that, originated, the, virus"
29845,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.108695652,"of, to, the, than, in"
29846,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.108695652,"and, cov, to, the, in"
29847,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.108695652,"in, the, of, to, cov"
29848,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.108695652,"of, the, or, evidence, supports"
29849,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.108695652,"a, from, for, the, is"
29850,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.108695652,"evidence, for, that, the, of"
29851,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.108695652,"on, of, have, is, which"
29852,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.108695652,"that, bats, and, the, of"
29853,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.108695652,"and, that, the, wuhan, of"
29854,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.108695652,"of, humans, in, and, to"
29855,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.108695652,"the, that, in, to, humans"
29856,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.108695652,"of, the, covid-19, virus, and"
29857,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.108695652,"the, of, that, virus, in"
29858,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.108695652,"transmitted, an, animal, to, in"
29859,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.108695652,"the, of, that, have, been"
29860,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.108695652,"the, of, which, that, was"
29861,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.108695652,"revealed, that, of, the, for"
29862,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.108695652,"bat, is, the, that, for"
29863,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.108695652,"that, were, found, in, asian"
29864,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.108695652,"with, the, covid-19, in, of"
29865,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.108695652,"with, the, of, were, two"
29866,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.108695652,"was, in, has, the, with"
29867,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.108695652,"the, in, of, a, horseshoe"
29868,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.108695652,"bats, have, the, in, china"
29869,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.108695652,"of, these, a, rhinolophus, in"
29870,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.108695652,"the, of, bats, and, can"
29871,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.108695652,"can, to, in, humans, and"
29872,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.108695652,"and, between, is, the, to"
29873,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.108695652,"bats, and, the, species, by"
29874,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.108695652,"bats, and, was, the, intermediate"
29875,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.108695652,"of, the, has, also, been, are, by, or, other, to"
29876,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.108695652,"a, of, and, the, in"
29877,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.108695652,"a, of, the, in, was"
29878,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.108695652,"in, the, of, and, a"
29879,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.108695652,"was, in, a, and, the"
29880,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.108695652,"of, and, the, in, between"
29881,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.108695652,"origin, of, sars-cov-2, have, been"
29882,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.108695652,"the, of, been, origin, is"
29883,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.108695652,"of, from, geographic, in, sars-cov-2"
29884,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.108695652,"the, of, sars-cov-2, with, is"
29885,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.108695652,"of, the, sequence, sars-cov-2, is"
29886,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.108695652,"the, of, 97.4%, similar, is"
29887,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.108695652,"of, the, is, similar, viral"
29888,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.108695652,"have, in, bats, the, china"
29889,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.108695652,"genome, that, sars-cov-2, and, a"
29890,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.108695652,"that, sars-cov-2, and, has, been"
29891,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.108695652,"the, is, associated, and, in"
29892,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.108695652,"the, virus, a, of, that"
29893,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.108695652,"is, of, the, virus, naturally"
29894,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.108695652,"to, the, of, and, virus"
29895,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.108695652,"to, of, the, virus, and"
29896,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.108695652,"or, the, by, of, are, to, has, been, other, also"
29897,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.108695652,"are, other, in, with, the"
29898,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.108695652,"in, it, that, sars-cov-2, first"
29899,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.108695652,"sars-cov-2, a, that, wildlife, to"
29900,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.108695652,"sars-cov-2, bat, to, that, in"
29901,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.108695652,"that, in, as, to, humans"
29902,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.108695652,"have, been, and, the, for"
29903,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.108695652,"from, as, transmission, for, the"
29904,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.108695652,"human, and, of, natural, the"
29905,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.108695652,"that, was, sars-cov-2, and, to"
29906,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.108695652,"the, of, its, to, sars-cov-2"
29907,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.108695652,"sars-cov-2, be, of, natural, the, and, with, high, to, in"
29908,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.108695652,"that, is, to, be, the"
29909,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.108695652,"the, most, to, of, and"
29910,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.108695652,"the, of, most, to, is"
29911,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.108695652,"the, on, that, be, sars-cov-2"
29912,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.108695652,"results, that, sars-cov-2, the, for"
29913,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.108695652,"that, sars-cov-2, the, bats, be"
29914,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.108695652,"from, to, sars-cov-2, and, the"
29915,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.108695652,"the, to, that, sars-cov-2, also"
29916,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.108695652,"using, the, clustering, that, sars-cov-2"
29917,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.108695652,"that, the, bats, to, a"
29918,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.108695652,"similar, are, bat, a, the"
29919,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.108695652,"the, to, of, a, bat"
29920,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.108695652,"of, to, a, which, bat"
29921,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.108695652,"a, to, bat, of, from"
29922,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.108695652,"of, sequences, in, from, was"
29923,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.108695652,"these, a, of, in, rhinolophus"
29924,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.108695652,"of, a, to, which, bat"
29925,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.108695652,"bat, to, sequence, in, of"
29926,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.108695652,"a, the, to, similarity, sars-cov-2"
29927,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.108695652,"sars-cov-2, to, human, receptor, in"
29928,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.108695652,"and, pangolin, to, of, sars-cov-2."
29929,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.108695652,"a, virus, to, for, the"
29930,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.108695652,"the, of, a, and, been"
29931,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.108695652,"the, for, and, have, been"
29932,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.108695652,"the, with, and, for, sars-cov-2"
29933,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.108695652,"to, the, have, as, sars-cov-2"
29934,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.108695652,"the, sars-cov-2, in, of, a"
29935,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.108695652,"genome, bats, to, be, the"
29936,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.108695652,"the, probable, for, sars-cov-2, at"
29937,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.108695652,"that, is, the, bat, for"
29938,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.108695652,"has, been, that, and, sars-cov-2"
29939,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.108695652,"that, the, sars-cov-2, in, bat"
29940,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.108695652,"the, to, and, cov, in"
29941,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.108695652,"the, likely, to, sars-cov-2, bat"
29942,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.108695652,"the, that, in, this, likely"
29943,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.108695652,"the, sars-cov-2, bats, in, this"
29944,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.108695652,"the, using, clustering, that, sars-cov-2"
29945,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.108695652,"the, of, and, sequences, sars-cov-2"
29946,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.108695652,"this, of, and, bat, the"
29947,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.108695652,"bat, similarity, is, sars-cov-2, the"
29948,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.108695652,"all, sars-cov-2, are, bat, the"
29949,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.108695652,"the, bat, and, with, 2"
29950,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.108695652,"sars-cov-2, may, in, that, or"
29951,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.108695652,"suggest, that, the, may, of"
29952,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.108695652,"on, the, virus, bat, and"
29953,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.108695652,"the, virus, from, in, and"
29954,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.108695652,"and, the, virus, of, bat"
29955,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.108695652,"the, bat, in, china, and"
29956,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.108695652,"the, sars-cov-2, to, of, found"
29957,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.108695652,"also, found, to, that, are"
29958,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.108695652,"to, similar, sars-cov-2, the, genome"
29959,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.108695652,"the, pangolin, that, a, of"
29960,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.108695652,"of, the, is, with, sars-cov-2"
29961,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.108695652,"and, of, sars-cov-2, is, the"
29962,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.108695652,"the, emergence, of, and, resulted"
29963,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.108695652,"the, for, of, that, and"
29964,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.108695652,"the, of, sars-cov-2, that, evidence"
29965,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.108695652,"of, evidence, that, the, for"
29966,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.108695652,"have, the, and, of, that"
29967,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.108695652,"sars-cov-2, together, with, sars-cov, and"
29968,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.108695652,"with, and, the, for, sars-cov-2"
29969,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.108695652,"sars-cov-2, in, and, residues, the"
29970,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.108695652,"and, sars-cov-2, to, the, in"
29971,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.108695652,"in, the, and, are, to"
29972,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.108695652,"and, that, of, in, pangolin"
29973,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.108695652,"that, the, virus, in, and"
29974,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.108695652,"the, of, natural, for, and"
29975,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.108695652,"this, of, and, in, the"
29976,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.108695652,"less, to, and, at, the"
29977,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.108695652,"this, in, the, of, that"
29978,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.108695652,"the, of, to, cov, in"
29979,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.108695652,"be, that, origin, of, sars-cov-2"
29980,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.108695652,"the, origin, to, that, virus"
29981,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.108695652,"the, that, of, has, origin"
29982,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.108695652,"that, bats, be, the, sars-cov-2"
29983,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.108695652,"the, virus, to, a, of"
29984,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.108695652,"the, of, a, zoonotic, to"
29985,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.108695652,"the, of, to, a, with"
29986,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.108695652,"was, that, the, in, as"
29987,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.108695652,"that, sars-cov-2, to, from, is"
29988,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.108695652,"the, and, be, intermediate, host"
29989,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.108695652,"the, study, of, suggested, intermediate"
29990,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.108695652,"the, virus, sars-cov-2, and, a"
29991,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.108695652,"that, the, virus, in, of"
29992,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.108695652,"the, sars-cov-2, animal, that, in"
29993,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.108695652,"the, from, possibly, a, in"
29994,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.108695652,"a, research, from, the, sars-cov-2"
29995,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.108695652,"to, and, with, the, of"
29996,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.108695652,"the, to, reservoir, of, and"
29997,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.108695652,"of, coronaviruses, from, a, sars-cov-2"
29998,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.108695652,"of, sars-cov-2, in, from, geographic"
29999,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.108695652,"of, that, sars-cov-2, coronavirus, to"
30000,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.108695652,"in, to, that, of, sars-cov-2"
30001,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.108695652,"genome, the, was, 96.2%, identity"
30002,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.108695652,"the, was, has, in, with"
30003,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.108695652,"sars-cov-2, the, of, in, yunnan"
30004,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.108695652,"sars-cov-2, the, in, that, of"
30005,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.108695652,"in, to, the, of, sars-cov-2"
30006,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.108695652,"in, of, sars-cov-2, to, that"
30007,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.108695652,"of, the, known, in, to"
30008,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.108695652,"of, to, sequence, bat, in"
30009,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.108695652,"may, the, of, to, that"
30010,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.108695652,"of, the, protein, as, pangolin"
30011,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.108695652,"the, sars-cov-2, to, be, with, high, in, of, natural, and"
30012,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.108695652,"of, pangolin, and, to, sars-cov-2."
30013,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.108695652,"the, is, that, sars-cov-2, a"
30014,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.108433735,"are, of, and, a, diversity, which, zoonotic, that, in"
30015,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.108433735,"and, the, bat, to, as, a, with, that, virus"
30016,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.108433735,"and, different, infect, other, that, in, turn, which, can"
30017,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.108433735,"or, bats, the, cave, species, of, are, and, in"
30018,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.108433735,"and, the, bat, to, are, closely, related, that, in"
30019,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.108433735,"the, virus, as, a, that, with, bat, and, to"
30020,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.108433735,"that, in, different, which, turn, can, infect, other, and"
30021,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.108433735,"the, to, that, are, closely, related, bat, in, and"
30022,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.108433735,"from, the, for, to, a, live, that, with, sars,, as, and, by, sars, in, of, taken, at, an"
30023,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.108433735,"the, of, that, in, a, sars, human, and, to"
30024,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.108433735,"as, a, of, the, at, and, live, by, in, an, to, sars, with, for, that, taken, from, sars,"
30025,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.108433735,"in, the, of, sars, a, that, to, human, and"
30026,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.108433735,"the, are, or, species, of, bats, in, cave, and"
30027,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.108433735,"a, of, that, diversity, and, are, zoonotic, in, which"
30028,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.108333333,"in, a, team, of, to, the, from, tested, positive, for, this, were, virus"
30029,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.108333333,"in, a, of, to, the, collected, from, for, this, and, sars, were, virus"
30030,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.108333333,"in, a, team, of, to, the, virus, this, from, were, for, tested, positive"
30031,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.108333333,"for, the, of, and, were, virus, collected, from, a, in, sars, this, to"
30032,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.108280255,"evidence, that, palm, civets, were, infected, from, in, the, market, a, at, and, large, of, animal, markets"
30033,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.108280255,"bat, had, to, a, as, from, in, multiple, the, by, positive., sars, were, of, and, species, horseshoe"
30034,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.108280255,"in, the, of, a, to, bat, as, by, had, positive., were, and, sars, from, multiple, species, horseshoe"
30035,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.108280255,"a, of, the, market, palm, civets, at, animal, and, markets, were, in, large, evidence, infected, that, from"
30036,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.108108108,"in, related, to, sars-cov-2"
30037,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.108108108,"animal, are, a, in"
30038,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.108108108,"of, a, in, animal"
30039,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.108108108,"in, the, two, are"
30040,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.108108108,"the, animal, reservoir, and"
30041,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.108108108,"species, of, to, and"
30042,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.108108108,"sequences, coronaviruses, and, in"
30043,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.108108108,"to, have, in, bat"
30044,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.108108108,"and, many, to, sars-cov"
30045,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.108108108,"sars-cov-2, many, and, emerged"
30046,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.108108108,"to, sars-cov-2, emerged, of"
30047,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.108108108,"to, sars-cov-2, and, of"
30048,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.108108108,"of, to, sars-cov-2, and"
30049,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.108108108,"of, sars-cov-2, sars-cov, and"
30050,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.108108108,"bats, of, sars-cov, and"
30051,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.108108108,"sars-cov-2, and, to, of"
30052,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.108108108,"of, and, coro-, navirus"
30053,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.108108108,"sars-cov, and, to, many"
30054,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.108108108,"the, sars-, cov-2, and"
30055,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.108108108,"sars-cov-2, to, in, is"
30056,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.108108108,"one, to, genome, in"
30057,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.108108108,"in, china, the, of"
30058,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.108108108,"of, that, sars-cov-2, coronavirus"
30059,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.108108108,"identified, been, from, is"
30060,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.108108108,"the, of, and, bat, coronaviruses, a, in, to"
30061,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.108108108,"of, to, is, a, found, in, sars-cov-2, the"
30062,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.108108108,"the, of, spike, in, a, human, and, to"
30063,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.108108108,"the, and, a, in, to, bat, coronaviruses, of"
30064,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.108108108,"and, sars-cov-2, emerged, many"
30065,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.108108108,"host, sars-cov-2, with, the"
30066,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.108108108,"the, bat, coronavirus,, with"
30067,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.108108108,"natural, origin, virus, and"
30068,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.108108108,"the, natural, and, a"
30069,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.108108108,"the, and, a, of"
30070,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.108108108,"the, reservoir, of, and"
30071,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.108108108,"its, and, to, the, of, that, sars-cov-2, have"
30072,"The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.108108108,"the, zoonotic, and, host"
30073,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.108108108,"an, host, to, a, are, as, and, in"
30074,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.108108108,"that, a, the, virus, an, into, increase, with, of, in, also, to"
30075,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.108108108,"the, is, coronavirus, also, a, that, can, in"
30076,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.108108108,"a, and, had, in"
30077,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.108108108,"to, that, in, human"
30078,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.108108108,"the, of, sars-cov-2,, as"
30079,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.108108108,"the, in, intermediate, of"
30080,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.108108108,"the, probably, has, in"
30081,"Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.108108108,"of, animal, in, wuhan"
30082,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.108108108,"suggested, that, in, animal"
30083,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.108108108,"were, in, to, animal"
30084,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.108108108,"animal, market, in, and"
30085,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.108108108,"were, to, in, and"
30086,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.108108108,"to, of, a, sars-cov-2"
30087,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.108108108,"the, to, a, is"
30088,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.108108108,"sars-cov-2, a, to, an"
30089,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.108108108,"that, bats, and, are"
30090,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.108108108,"and, the, of, hosts"
30091,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.108108108,"and, of, natural, the"
30092,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.108108108,"through, the, sars-cov-2, of"
30093,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.108108108,"with, of, at, the"
30094,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.108108108,"to, the, a, high"
30095,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.108108108,"due, to, a, the"
30096,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.108108108,"to, the, of, into"
30097,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.108108108,"of, to, which, the"
30098,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.108108108,"and, was, in, the"
30099,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.108108108,"the, in, humans, through"
30100,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.108108108,"humans, was, in, the"
30101,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.108108108,"the, outbreak, in, china"
30102,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.108108108,"that, is, of, bat"
30103,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.108108108,"in, of, sars-cov-2, the"
30104,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.108108108,"protein, the, of, sars-cov-2"
30105,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.108108108,"that, the, in, sars-cov-2"
30106,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.108108108,"the, of, in, that"
30107,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.108108108,"the, of, shows, that"
30108,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.108108108,"coro-, navirus, of, and"
30109,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.108108108,"the, whole, genome, that"
30110,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.108108108,"the, are, of, that"
30111,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.108108108,"are, the, that, sars"
30112,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.108108108,"the, of, that, are"
30113,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","civet cats and raccoon dogs  

are the intermediate hosts",0.108108108,"intermediate, hosts, and, the"
30114,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.108108108,"the, transmitted, to, and"
30115,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.108108108,"to, sars-cov-2, bats, and"
30116,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.108108108,"is, identified, from, been"
30117,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.108108108,"is, evidence, sars-cov-2, in"
30118,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.108108108,"is, sars-cov-2, through, of"
30119,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.108108108,"and, in, by, the"
30120,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.108108108,"the, zoonotic, by, a"
30121,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.108108108,"a, the, that, was"
30122,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.108108108,"are, a, as, and, in, to, an, host"
30123,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.108108108,"sars-cov-2, emerged, to, of"
30124,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.108108108,"the, into, to, of"
30125,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.108108108,"that, a, sars-cov-2, to"
30126,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.108108108,"the, sars-cov-2, origin, of"
30127,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.108108108,"sars-cov-2, that, into, the"
30128,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.108108108,"to, sars-cov-2, at, the"
30129,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.108108108,"from, the, huanan, animals"
30130,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.108108108,"the, most, of, intermediate"
30131,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.108108108,"at, the, huanan, market"
30132,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.108108108,"zoonotic, from, the, for"
30133,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.108108108,"sars-cov-2, the, of, through"
30134,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.108108108,"the, of, huanan, market"
30135,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.108108108,"are, to, transmission, be"
30136,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.108108108,"that, sars-cov-2, to, through"
30137,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.108108108,"the, two, are, in"
30138,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.108108108,"that, market, in, the"
30139,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.108108108,"the, are, to, that"
30140,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.108108108,"a, origin, and, in"
30141,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.108108108,"the, lineage, by, from"
30142,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.108108108,"were, because, the, in"
30143,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.108108108,"and, the, reservoir, animal"
30144,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.108108108,"and, animal, market, in"
30145,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.108108108,"that, the, huanan, and"
30146,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.108108108,"the, genomic, that, sars-cov-2"
30147,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.108108108,"sars-cov-2, was, and, the"
30148,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.108108108,"animal, was, the, likely"
30149,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.108108108,"a, in, had, and"
30150,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.108108108,"an, animal, in, and"
30151,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.108108108,"into, in, to, sars-cov-2"
30152,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.108108108,"that, a, with, sars-cov-2"
30153,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.108108108,"a, sars-cov-2, the, in"
30154,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.108108108,"in, that, sars-cov-2, the"
30155,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.108108108,"natural, of, the, most"
30156,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.108108108,"to, were, and, the"
30157,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.108108108,"of, cases, a, to, early, the, only, in"
30158,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.108108108,"sars-cov-2, evidence, in, is"
30159,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.108108108,"a, was, that, the, same, for, to, is"
30160,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.108108108,"evidence, to, sars-cov-2, a, of, the, and, that"
30161,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.108108108,"that, the, a, market, live, animals, in, to"
30162,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.108108108,"that, has, a, and"
30163,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.108108108,"with, to, the, virus"
30164,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.108108108,"the, similarity, with, to"
30165,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.108108108,"the, from, animals, huanan"
30166,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.108108108,"the, huanan, that, and"
30167,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.108108108,"and, the, virus, from"
30168,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.108108108,"of, and, species, to"
30169,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.108108108,"of, that, to, coronaviruses"
30170,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.108108108,"a, that, to, of"
30171,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.108108108,"and, species, to, of"
30172,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.108108108,"have, that, of, to"
30173,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.108108108,"all, that, origin, and"
30174,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.108108108,"have, in, that, which"
30175,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.108108108,"the, was, and, in"
30176,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.108108108,"of, in, the, horseshoe"
30177,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.108108108,"of, the, in, and"
30178,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.108108108,"that, the, was, first"
30179,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.108108108,"the, sequence, that, and"
30180,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.108108108,"the, and, to, that"
30181,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.108108108,"of, the, to, was"
30182,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.108108108,"the, of, in, with"
30183,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.108108108,"the, of, a, to, in, and, market, were"
30184,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.108108108,"the, virus, which, in"
30185,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.108108108,"this, the, or, of"
30186,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.108108108,"this, that, in, or"
30187,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.108108108,"transmitted, to, intermediate, host."
30188,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.108108108,"the, sars-cov-2, from, a"
30189,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.108108108,"the, to, sars-cov-2, malayan"
30190,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.108108108,"he, protein, with, of"
30191,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.108108108,"and, can, to, humans"
30192,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.108108108,"the, of, covid-19,, and"
30193,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.108108108,"sars-cov-2, has, a, and"
30194,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.108108108,"and, the, bat, of"
30195,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.108108108,"the, is, of, to"
30196,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.108108108,"from, the, and, virus"
30197,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.108108108,"zoonotic, to, the, that"
30198,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.108108108,"that, the, is, at"
30199,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.108108108,"no, virus, was, the"
30200,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.108108108,"a, virus, that, the"
30201,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.108108108,"virus, and, natural, origin"
30202,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.108108108,"were, to, and, in"
30203,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.108108108,"to, started, the, in"
30204,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.108108108,"sars-cov, and, to, in"
30205,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.108108108,"the, and, that, to"
30206,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.108108108,"the, that, virus, in"
30207,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.108108108,"the, of, outbreak, in"
30208,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.108108108,"the, also, bat, and"
30209,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.108108108,"the, to, that, of"
30210,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.108108108,"bats, of, virus, the"
30211,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.108108108,"the, to, that, and"
30212,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.108108108,"if, the, be, infected"
30213,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.108108108,"the, in, from, market"
30214,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.108108108,"cases, and, at, the, huanan, seafood, market,, or, was, of, a, by"
30215,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.108108108,"that, the, bat, reservoir"
30216,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.108108108,"in, that, the, market"
30217,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.108108108,"the, first, that, was"
30218,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.108108108,"the, market, that, in"
30219,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.108108108,"in, it, that, the"
30220,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.108108108,"a, of, the, that, were, wuhan, with, seafood"
30221,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.108108108,"of, reported, to, the"
30222,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.108108108,"reported, the, to, sars-cov-2"
30223,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.108108108,"of, the, to, bat"
30224,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.108108108,"the, sars-cov-2, bat, cov)"
30225,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.108108108,"the, sars-cov-2, of, to"
30226,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.108108108,"a, to, the, that, was, is, for, same"
30227,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.108108108,"the, is, by, for, a, to, that, same"
30228,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.108108108,"according, to, is, bat"
30229,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.108108108,"that, bat, the, reservoir"
30230,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.108108108,"the, reservoir, of, bat"
30231,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.108108108,"that, has, the, of"
30232,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.108108108,"isolated, from, are, the"
30233,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.108108108,"the, isolated, from, in"
30234,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.108108108,"in, of, the, protein"
30235,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.108108108,"of, data, that, is"
30236,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.108108108,"genetic, data, that, is"
30237,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.108108108,"of, is, and, sars-cov"
30238,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.108108108,"recombination, and, that, of"
30239,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.108108108,"has, the, in, probably"
30240,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.108108108,"the, in, which, virus"
30241,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.108108108,"virus, its, the, most"
30242,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.108108108,"in, the, which, virus"
30243,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.108108108,"is, to, that, virus"
30244,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.108108108,"from, to, the, humans"
30245,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.108108108,"it, is, a, the"
30246,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.108108108,"a, the, virus, is"
30247,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.108108108,"a, the, virus, to"
30248,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.108108108,"closely, related, to, the"
30249,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.108108108,"the, are, isolated, from"
30250,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.108108108,"the, from, to, genus"
30251,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.108108108,"bat, from, coronaviruses, sars-cov-2"
30252,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.108108108,"in, the, outbreak, of"
30253,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.108108108,"of, in, bats, the"
30254,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.108108108,"of, the, to, sars"
30255,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.108108108,"also, to, the, of"
30256,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.108108108,"and, the, asia,, in"
30257,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.108108108,"and, in, an, animal"
30258,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.108108108,"the, and, an, animal"
30259,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.108108108,"a, is, that, and"
30260,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.108108108,"a, that, has, and"
30261,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.108108108,"that, sars-cov-2, all, and"
30262,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.108108108,"the, sars-cov-2, from, humans"
30263,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.108108108,"that, the, sars-cov-2, from"
30264,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.108108108,"that, the, and, sars-cov-2"
30265,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.108108108,"and, that, the, is"
30266,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.108108108,"the, and, that, sars-cov-2"
30267,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.108108108,"the, of, to, covid-19"
30268,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.108108108,"the, to, covid-19, from"
30269,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.108108108,"the, as, well, and"
30270,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.108108108,"are, and, the, to"
30271,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.108108108,"the, to, that, zoonotic"
30272,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.108108108,"that, to, the, and"
30273,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.108108108,"the, genomic, sars-cov-2, that"
30274,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.108108108,"coronaviruses, that, of, to"
30275,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.108108108,"the, coronavirus, sequence, sars-cov-2"
30276,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.108108108,"the, analysis, that, to"
30277,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.108108108,"of, the, novel, and"
30278,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.108108108,"the, has, coronavirus, with"
30279,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.108108108,"the, of, bat, coronavirus"
30280,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.108108108,"has, the, of, to"
30281,"�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.108108108,"sars, bat, and, the"
30282,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.108108108,"of, sequences, shows, in"
30283,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.108108108,"the, natural, a, and"
30284,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.108108108,"the, by, a, laboratory"
30285,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.108108108,"et, that, the, sars-cov-2, by, selection, natural, and"
30286,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.108108108,"to, sars-cov-2, after, in"
30287,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.108108108,"is, at, that, the"
30288,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.108108108,"the, and, transmitted, to"
30289,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.108108108,"that, the, market, in, to, live, animals, a"
30290,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.108108108,"is, are, the, hosts"
30291,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.108108108,"were, and, in, at"
30292,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.108108108,"in, the, of, a, virus, from, and, sequence"
30293,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.108108108,"this, in, that, virus"
30294,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.108108108,"in, is, that, sars-cov-2"
30295,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.108108108,"from, in, bat, virus"
30296,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.108108108,"of, based, on, the, in, analysis, s, protein"
30297,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.108108108,"sars-cov, and, sars-cov-2, of"
30298,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.108108108,"the, two, of, with"
30299,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.108108108,"the, and, to, a, of, in, bat, coronaviruses"
30300,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.108108108,"humans, the, and, sars-cov-2"
30301,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.108108108,"are, the, bats, to"
30302,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.108108108,"of, most, to, the"
30303,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.108108108,"the, of, to, sars-"
30304,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.108108108,"coronaviruses, in, bats, which, to, that, sars-cov-2, and"
30305,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.108108108,"is, to, the, most"
30306,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.108108108,"is, pangolin, to, the"
30307,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.108108108,"the, is, to, pangolin"
30308,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.108108108,"the, sequence, sars-cov-2, coronavirus"
30309,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.108108108,"that, a, of, coronavirus"
30310,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.108108108,"a, that, the, was"
30311,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.108108108,"a, that, of, to"
30312,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.108108108,"the, that, of, a"
30313,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.108108108,"the, that, to, sars-"
30314,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.108108108,"the, results, that, a"
30315,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.108108108,"sars-cov-2, with, infected, the"
30316,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.108108108,"the, of, reported, to"
30317,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.108108108,"data, that, is, of"
30318,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.108108108,"our, the, that, sars-cov-2"
30319,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.108108108,"the, at, huanan, market"
30320,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.108108108,"the, to, market, in"
30321,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.108108108,"the, to, started, in"
30322,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.108108108,"the, sars-cov-2, was, and"
30323,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.108108108,"bats, in, closely, related"
30324,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.108108108,"sars-cov-2, been, viruses, bats"
30325,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.108108108,"the, an, that, of"
30326,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.108108108,"the, of, spillover, origin"
30327,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.108108108,"the, reservoir, an, of"
30328,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.108108108,"ratg13, the, of, sars-cov-2"
30329,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.108108108,"a, the, and, sars-cov-2"
30330,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.108108108,"the, pangolins, of, sars-cov-2"
30331,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.108108108,"a, of, the, as"
30332,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.108108108,"the, that, its, was, of, sars-cov-2, in, this"
30333,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.108108108,"ratg13, to, sars-cov-2, pangolin"
30334,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.108108108,"to, the, by, a"
30335,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.108108108,"the, virus, of, a"
30336,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.108108108,"the, virus, bats, of"
30337,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.108108108,"bats, the, of, virus"
30338,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.108108108,"a, bat, the, of"
30339,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.108108108,"a, the, and, in"
30340,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.108108108,"the, presence, in, of"
30341,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.108108108,"the, bat, in, of"
30342,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.108108108,"covs, that, are, to"
30343,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.108108108,"sars-cov-2, and, in, zoonotic"
30344,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.108108108,"the, for, sars-cov-2, to"
30345,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.108108108,"the, as, host, for"
30346,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.108108108,"sars-cov-2, with, the, host"
30347,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.108108108,"were, because, in, the"
30348,"All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.108108108,"the, in, a, sars-cov-2"
30349,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.108108108,"pangolins, the, for, sars-cov-2"
30350,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.108108108,"to, the, high, a"
30351,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.108108108,"the, high, of, to"
30352,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.108108108,"bat, be, the, of"
30353,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.108108108,"no, the, virus, was"
30354,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.108108108,"the, been, was, by"
30355,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.108108108,"the, sars-cov-2, to, consistent"
30356,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.108108108,"sars-cov-2, related, to, in"
30357,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.108108108,"sars-cov-2, into, in, to"
30358,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.108108108,"the, is, not, to"
30359,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.108108108,"a, and, with, sars-cov-2, has, to, in, the"
30360,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.108108108,"the, sars-cov-2, to, a, of, is, found, in"
30361,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.108108108,"in, coronaviruses, sequences, and"
30362,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.108108108,"with, a, of, in"
30363,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.108108108,"with, a, that, sars-cov-2"
30364,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.108108108,"that, of, in, sars-cov-2"
30365,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.108108108,"in, that, of, bat"
30366,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.108108108,"sars-cov-2, bat, similarity, of"
30367,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.108108108,"is, the, sars-cov-2, that"
30368,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.108108108,"the, to, from, market"
30369,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.108108108,"the, virus, to, from"
30370,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.108108108,"to, virus, from, the"
30371,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.108108108,"the, virus, with, identity"
30372,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.108108108,"the, and, sars-, cov-2"
30373,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.108108108,"the, and, that, sequence"
30374,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.108108108,"the, has, to, of"
30375,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.108108108,"to, the, of, high"
30376,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.108108108,"to, in, ratg13, the"
30377,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","bats are also important reservoir species for a great 

range of coronaviruses",0.108108108,"of, species, also, for"
30378,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.108108108,"with, bat, coronavirus,, the"
30379,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.108108108,"the, sars-cov-2, protein, of"
30380,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.108108108,"the, of, sars-cov-2, has"
30381,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.108108108,"he, with, protein, of"
30382,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.108108108,"one, from, and, amino, acid, to, in, the"
30383,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.108108108,"due, to, the, a"
30384,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.108108108,"the, ratg13, to, in"
30385,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.108108108,"rbd, sars-cov-2, the, in"
30386,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.108108108,"sars-cov-2, a, of, in, the, and, that, with"
30387,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.108108108,"to, in, the, and, it, has, been, that"
30388,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.108108108,"the, sars-cov-2, reported, to"
30389,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.108108108,"the, sars-cov-2, a, and"
30390,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.108108108,"the, rbd, to, ace2"
30391,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.108108108,"the, amino, acid, sars-cov-2"
30392,"bats are also important reservoir species for a great 

range of coronaviruses","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.108108108,"also, species, for, of"
30393,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.108108108,"the, an, to, from"
30394,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.108108108,"to, very, the, host"
30395,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.108108108,"that, laboratory, of, a"
30396,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.108108108,"at, to, the, sars-cov-2"
30397,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.108108108,"and, in, were, at"
30398,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.108108108,"the, in, susceptible, at"
30399,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.108108108,"susceptible, in, at, the"
30400,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.108108108,"the, genetic, that, from"
30401,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.108108108,"sars-cov-2, to, bat, in"
30402,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.108108108,"like, found, in, with"
30403,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.108108108,"the, of, market, in"
30404,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.108108108,"that, a, the, of, sars-cov-2, and, evidence, to"
30405,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.108108108,"it, has, been, in, the, and, to, that"
30406,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.108108108,"sars-cov-2, is, a, or"
30407,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Bats are the second  

largest order of mammals, with over 1,230 species.",0.108108108,"the, with, bats, are"
30408,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.108108108,"the, malayan, to, sars-cov-2"
30409,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.108108108,"the, of, bat, reservoir"
30410,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.108108108,"all, that, sars-cov-2, and"
30411,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.108108108,"to, date, that, in"
30412,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.108108108,"most, the, in, that"
30413,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.108108108,"bat, the, sars-cov-2, and"
30414,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.108108108,"the, in, and, for"
30415,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.108108108,"sars-cov-2, to, a, of"
30416,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.108108108,"is, sars-cov-2, related, coronavirus"
30417,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.108108108,"a, and, with, sars-cov-2, other, to, in, the"
30418,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.108108108,"rbd, of, to, the"
30419,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.108108108,"a, that, the, same, for, to, is, by"
30420,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.108108108,"the, of, to, than"
30421,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","This suggests that the BANAL series may be able to directly infect  

humans.",0.108108108,"this, to, the, that"
30422,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.108108108,"in, from, of, the"
30423,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.108108108,"is, the, in, of"
30424,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.108108108,"amino, acid, the, sars-cov-2"
30425,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.108108108,"the, virus, is, most"
30426,"Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.108108108,"if, the, infected, be"
30427,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.108108108,"the, sars-cov-2, and, humans"
30428,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.108108108,"zoonotic, the, events, that"
30429,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.108108108,"the, that, with, were"
30430,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.108108108,"that, the, with, wuhan, seafood, were, a, of"
30431,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.108108108,"also, a, the, of, virus, in, with, that, increase, to, an, into"
30432,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.108108108,"the, as, a, species, of, that, from, to, civets, infected, by, and"
30433,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.108108108,"from, a, to, in, the, suggests, that, human"
30434,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.108108108,"the, that, a, virus, found, in, this, evidence"
30435,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.108108108,"a, sequence, and, the, of, virus, from, in"
30436,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.108108108,"in, a, of, were, found, to, infected, that"
30437,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.108108108,"among, the, and, for, of, a, to, team, were, in, this, sars, more, than, other, at"
30438,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.108108108,"early, cases, in, only, the, of, a, to"
30439,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.108108108,"in, a, team, of, to, the, for, among, this, and, sars, at, were, more, than, other"
30440,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.108108108,"the, spillover, origin, of"
30441,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.108108108,"are, in, a, animal"
30442,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.108108108,"the, sars, that, are"
30443,"The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.108108108,"the, that, events, zoonotic"
30444,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.108108108,"this, that, are, the"
30445,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.108108108,"a, market,, the, huanan, seafood, at, was, and, of, cases, by, or"
30446,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.108108108,"this, its, in, the, of, that, sars-cov-2, was"
30447,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.108108108,"the, virus, most, its"
30448,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.108108108,"infected, with, sars-cov-2, the"
30449,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","expended to make the simple point 

that COVID-19 had a natural origin.",0.108108108,"covid-19, a, the, that"
30450,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.108108108,"sars-cov-2, bats, and, to"
30451,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.108108108,"from, bats, to, and"
30452,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.",0.108108108,"the, and, host, zoonotic"
30453,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.108108108,"a, natural, and, in"
30454,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.108108108,"viruses, a, which, of"
30455,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.108108108,"the, their, and, of"
30456,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.108108108,"a, and, origin, in"
30457,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.108108108,"a, has, sars-cov-2, and"
30458,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.108108108,"sars-cov-2, in, zoonotic, and"
30459,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.108108108,"a, in, natural, and"
30460,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.108108108,"that, the, virus, a"
30461,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.108108108,"the, sars-cov-2, with, its"
30462,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.108108108,"is, sars-cov-2, or, a"
30463,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.108108108,"sars-cov-2, through, of, is"
30464,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.108108108,"that, of, a, laboratory"
30465,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.108108108,"related, coronavirus, is, sars-cov-2"
30466,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.108108108,"of, that, laboratory, is"
30467,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.108108108,"that, sars-cov-2, a, coronavirus"
30468,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.108108108,"data, genetic, that, is"
30469,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.108108108,"the, genetic, from, that"
30470,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.108108108,"of, sars-, cov-2, likely"
30471,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.108108108,"the, that, from, a, in, human, suggests, to"
30472,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.108108108,"the, shows, that, of"
30473,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.108108108,"a, the, it, is"
30474,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.108108108,"the, of, sars-cov-2, pangolins"
30475,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.108108108,"the, presence, of, in"
30476,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.108108108,"of, the, coronavirus, bat"
30477,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.108108108,"the, that, virus, a, found, in, this, evidence"
30478,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.108108108,"the, spike, and, to, a, of, in, human"
30479,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.108108108,"the, genetic, of, to"
30480,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.108108108,"from, to, the, genus"
30481,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.108108108,"a, of, viruses, which"
30482,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.108108108,"that, might, the, of"
30483,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.108108108,"analysis, suggests, that, the"
30484,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.108108108,"to, humans, and, can"
30485,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.108108108,"to, covs, that, are"
30486,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.108108108,"were, humans, in, to"
30487,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.108108108,"to, transmitted, intermediate, host."
30488,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.108108108,"the, to, be, is"
30489,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.108108108,"covid-19, be, in, the"
30490,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.108108108,"was, that, the, of"
30491,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.108108108,"that, have, in, which"
30492,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.108108108,"been, by, was, the"
30493,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.108108108,"the, that, most, in"
30494,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.108108108,"to, the, most, of"
30495,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.108108108,"like, with, found, in"
30496,"The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.108108108,"the, that, were, with"
30497,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.108108108,"the, huanan, market, of"
30498,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.108108108,"of, the, with, two"
30499,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.108108108,"in, the, of, horseshoe"
30500,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.108108108,"that, is, the, reservoir"
30501,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.108108108,"the, species, reservoir, of"
30502,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.108108108,"lineage, the, by, from"
30503,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.108108108,"the, in, isolated, from"
30504,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.108108108,"bat, from, in, china"
30505,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.108108108,"the, bats, to, and"
30506,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.108108108,"to, bats, and, from"
30507,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.108108108,"bats, and, humans, the"
30508,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.108108108,"the, and, from, bats"
30509,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.108108108,"the, was, in, humans"
30510,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.108108108,"the, and, by, in"
30511,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.108108108,"bats, humans, and, the"
30512,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.108108108,"are, to, be, transmission"
30513,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.108108108,"the, of, were, in, to, a, and, market"
30514,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.108108108,"in, the, of, identical, to, at, which, virus"
30515,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.108108108,"covid-19,, and, the, of"
30516,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.108108108,"in, the, asia,, and"
30517,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.108108108,"the, that, of, and"
30518,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.108108108,"is, to, a, the"
30519,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.108108108,"the, a, bridging, species, of, from, to, and"
30520,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.108108108,"the, of, from, that, civets, as, to, species, infected, by, a, and"
30521,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.108108108,"a, of, and, the, to, from, species, bridging"
30522,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.108108108,"in, the, to, sars-cov-2, has, with, and, a"
30523,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.108108108,"the, and, amino, acid, in, from, one, to"
30524,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.108108108,"in, a, with, other, and, to, sars-cov-2, the"
30525,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.108108108,"a, other, to, in, with, sars-cov-2, the, and"
30526,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.108108108,"is, very, in, the"
30527,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.108108108,"to, the, of, for"
30528,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.108108108,"the, of, to, virus"
30529,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.108108108,"and, of, the, virus"
30530,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.108108108,"the, other, by, not"
30531,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.108108108,"sars-cov-2, to, a, an"
30532,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.108108108,"to, a, from, sars-cov-2"
30533,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.108108108,"that, sars-cov-2, a, not"
30534,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.108108108,"to, that, sars-cov-2, a"
30535,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.108108108,"through, that, to, sars-cov-2"
30536,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.108108108,"that, is, a, to"
30537,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.108108108,"a, to, that, sars-cov-2"
30538,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.108108108,"is, that, laboratory, of"
30539,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.108108108,"sars-cov-2, to, in, after"
30540,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.108108108,"the, of, its, to, that, have, and, sars-cov-2"
30541,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.108108108,"the, for, zoonotic, from"
30542,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.108108108,"the, animal, was, likely"
30543,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.108108108,"that, animal, in, suggested"
30544,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.108108108,"bat, cov, the, sars-cov-2"
30545,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.108108108,"to, sars-cov-2, the, be"
30546,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.108108108,"of, the, most, natural"
30547,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.108108108,"is, the, most, virus"
30548,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.108108108,"the, as, and, well"
30549,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.108108108,"identical, to, sars-cov-2, that"
30550,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.108108108,"sars-cov-2, and, coronaviruses, to, which, that, in, bats"
30551,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.108108108,"sars-cov-2, with, of, similarity"
30552,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.108108108,"that, the, from, viruses"
30553,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.108108108,"the, with, similarity, to"
30554,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.108108108,"to, consistent, the, sars-cov-2"
30555,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.108108108,"the, coronaviruses, to, sars-cov-2"
30556,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.108108108,"with, the, sars-cov-2, its"
30557,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.108108108,"the, which, to, of"
30558,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.108108108,"the, rbd, sars-cov-2, in"
30559,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.108108108,"the, of, to, rbd"
30560,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.108108108,"also, a, coronavirus, the, is, can, in, that"
30561,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.108108108,"the, by, et, that, sars-cov-2, natural, selection, and"
30562,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.108108108,"that, sars-cov-2, the, with, of, complete, and, to"
30563,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.108108108,"pangolins, for, sars-cov-2, the"
30564,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.108108108,"bat, and, also, the"
30565,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.108108108,"results, that, the, a"
30566,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.108108108,"sars-cov-2, that, bats, and"
30567,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.108108108,"that, the, virus, for"
30568,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.108108108,"also, are, for, the"
30569,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.108108108,"hosts, are, the, is"
30570,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.108108108,"a, the, sars-cov-2, that"
30571,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.108108108,"sars-cov-2, to, the, for"
30572,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.108108108,"the, that, for, sars-cov-2"
30573,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.108108108,"it, that, the, bat"
30574,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.108108108,"the, in, bat, origin"
30575,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.108108108,"one, to, in, genome"
30576,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.108108108,"shows, in, sequences, of"
30577,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.108108108,"for, that, in, sars-cov-2"
30578,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.108108108,"to, as, sars-cov-2, the"
30579,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.108108108,"sars-cov-2, to, ratg13, pangolin"
30580,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.108108108,"in, the, results, and, to, that, are, closest"
30581,"Bats are the second  

largest order of mammals, with over 1,230 species.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.108108108,"bats, are, the, with"
30582,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.108108108,"viruses, sars-cov-2, been, bats"
30583,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.108108108,"from, bats, and, the"
30584,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.108108108,"suggests, that, the, sars-cov-2"
30585,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.108108108,"the, pangolin, is, to"
30586,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same",0.108108108,"and, the, sars, bat"
30587,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.108108108,"in, bat, have, to"
30588,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.108108108,"the, host, to, very"
30589,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.108108108,"the, in, is, very"
30590,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.108108108,"are, closest, to, the, results, in, and, that"
30591,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.108108108,"this, of, the, or"
30592,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.108108108,"the, of, pangolin, cov"
30593,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.108108108,"that, the, has, bat"
30594,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.108108108,"sars-cov-2, that, bats, the"
30595,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.108108108,"are, this, the, that"
30596,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.108108108,"the, sars-cov-2, of, origin"
30597,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.108108108,"of, their, and, the"
30598,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.108108108,"this, in, that, or"
30599,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.108108108,"from, virus, in, bat"
30600,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.108108108,"the, of, also, to"
30601,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.108108108,"to, and, with, sars-cov-2"
30602,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.108108108,"that, sars-cov-2, and, has"
30603,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.108108108,"and, sars-cov, is, of"
30604,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.108108108,"the, sars-cov-2, and, is"
30605,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.108108108,"is, the, to, of"
30606,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.108108108,"analysis, that, the, sars-cov-2"
30607,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.108108108,"the, of, sars-cov-2, for"
30608,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.108108108,"of, the, and, that"
30609,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.108108108,"and, that, recombination, of"
30610,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.108108108,"and, the, of, that"
30611,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.108108108,"and, that, of, the"
30612,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.108108108,"of, that, the, and"
30613,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.108108108,"that, for, sars-cov-2, in"
30614,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.108108108,"sars-cov, and, bats, of"
30615,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.108108108,"the, and, sars-cov-2, with"
30616,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.108108108,"in, the, and, sars-cov-2"
30617,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.108108108,"the, that, and, of"
30618,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.108108108,"the, of, that, might"
30619,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.108108108,"the, that, for, virus"
30620,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.108108108,"and, pangolin, the, of"
30621,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.108108108,"that, in, the, it"
30622,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.108108108,"that, bat, in, of"
30623,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.108108108,"to, the, from, sars-cov-2"
30624,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.108108108,"the, of, which, to, in, virus, identical, at"
30625,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.108108108,"the, pangolin, of, cov"
30626,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.108108108,"the, by, a, zoonotic"
30627,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.108108108,"a, recombinant, virus, the"
30628,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.108108108,"bat, origin, the, in"
30629,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.108108108,"that, to, is, likely"
30630,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.108108108,"from, that, sars-cov-2, to"
30631,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.108108108,"the, an, animal, and"
30632,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.108108108,"and, the, of, bat"
30633,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.108108108,"the, of, be, bat"
30634,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.108108108,"the, sars-cov-2, bat, and"
30635,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.108108108,"the, sars-cov-2, and, a"
30636,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.108108108,"sars-cov-2, the, virus, and"
30637,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.108108108,"the, a, recombinant, virus"
30638,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.108108108,"in, a, of, animal"
30639,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.108108108,"the, covid-19, be, in"
30640,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.108108108,"the, an, reservoir, of"
30641,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.108108108,"sars-cov-2, from, coronaviruses, bat"
30642,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.108108108,"a, and, origin, the"
30643,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.108108108,"the, for, zoonotic, and"
30644,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.108108108,"the, also, are, for"
30645,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.108108108,"in, of, a, found, that, infected, were, to"
30646,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.108108108,"in, yunnan, was, the"
30647,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.108108108,"the, was, to, in"
30648,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.108108108,"was, in, yunnan, the"
30649,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.108108108,"the, has, a, of, that, to, bat, and"
30650,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.108108108,"analysis, based, on, in, the, s, protein, of"
30651,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.108108108,"sars-cov-2, the, of, identity"
30652,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.108108108,"bat, similarity, of, sars-cov-2"
30653,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.108108108,"that, the, sars-cov-2, suggests"
30654,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.108108108,"analysis, that, sars-cov-2, the"
30655,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.107913669,"cases, with, the, huanan, market,, and, of, a, exposure, or, to, were, by, at, market"
30656,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.107913669,"a, market,, the, huanan, with, at, and, market, of, cases, were, to, by, or, exposure"
30657,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.107843137,"the, to, a, of, “the, is, most, likely, was, that, and"
30658,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.107843137,"in, a, of, yunnan, province,, the, from, bat, and, genome, virus"
30659,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.107843137,"the, of, a, bats,, bats, with, as, and, were, it, for"
30660,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.107843137,"the, not, to, have, that, been, in, with, of, living, animals"
30661,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.107843137,"by, the, of, a, viruses, in, species, and, similar, southern, asia"
30662,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.107843137,"the, that, of, human, cases, with, in, all, but, at, also"
30663,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.107843137,"with, the, of, bats, were, as, a, for, it, bats,, and"
30664,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.107843137,"of, asia, and, southern, similar, viruses, by, a, species, in, the"
30665,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.107843137,"genome, a, and, the, of, virus, from, bat, in, yunnan, province,"
30666,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.107843137,"a, of, the, chinese, at, also, by, or, other, to, virus"
30667,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.107843137,"most, that, a, was, likely, the, of, and, “the, is, to"
30668,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.107843137,"that, the, human, with, cases, of, in, at, also, but, all"
30669,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.107843137,"of, the, have, been, to, animals, in, not, with, that, living"
30670,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.107843137,"at, to, a, chinese, the, virus, or, by, of, other, also"
30671,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.107692308,"that, the, sarbecovirus, of, bats, and, pangolins"
30672,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.107692308,"it, was, sars-cov-2, to, is, used, in"
30673,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.107692308,"a, the, as, of, is, it, with"
30674,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.107692308,"the, with, of, sars-cov-2, is, it, as"
30675,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.107692308,"in, a, of, sars-cov-2, found, to, be"
30676,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.107692308,"from, in, also, the, that, a, sars-cov-2"
30677,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.107692308,"the, that, also, genetic, sars-cov-2, is, laboratory"
30678,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.107692308,"found, to, that, the, of, is, sars-cov-2"
30679,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.107692308,"in, which, more, that, of, and, sequences"
30680,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.107692308,"the, is, of, to, a, virus, in"
30681,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.107692308,"the, that, virus, can, be, in, with"
30682,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.107692308,"the, of, that, are, to, a, with"
30683,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.107692308,"the, is, and, an, with, to, of"
30684,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.107692308,"in, the, and, to, that, is, closest"
30685,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.107692308,"sars-cov, and, to, the, of, that, sars-cov-2"
30686,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.107692308,"was, that, the, with, in, animals, a"
30687,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.107692308,"to, that, sars-cov-2, has, been, with, and"
30688,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.107692308,"bat, species, in, as, a, to, genetic"
30689,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.107692308,"that, their, origin, in, which, and, from"
30690,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.107692308,"that, the, of, viruses, sars-cov-2, before, pandemic"
30691,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.107692308,"the, of, intermediate, host, at, from, humans"
30692,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.107692308,"result, from, of, in, the, and, been"
30693,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.107692308,"in, the, was, at, that, and, than"
30694,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.107692308,"the, in, market, live, animals, a, of"
30695,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.107692308,"and, a, of, sars-cov-2, in, an, the"
30696,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.107692308,"also, that, sars-cov-2, from, a, the, in"
30697,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.107692308,"in, the, of, to, that, sars-cov-2, a"
30698,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.107692308,"in, a, two, sars-, to, sars-cov-2, the"
30699,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.107692308,"also, a, of, sars-cov-2, in, the, to"
30700,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.107692308,"in, was, it, is, used, to, sars-cov-2"
30701,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.107692308,"there, are, other, to, in, sars-cov-2, and"
30702,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.107692308,"and, sars-cov-2, in, is, an, viruses, to"
30703,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.107692308,"the, of, are, to, sars-cov-2., is, that"
30704,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.107692308,"the, of, first, covid-19, were, market, in"
30705,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.107692308,"the, a, of, about, to, that, and"
30706,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.107692308,"that, a, of, to, and, the, sars-cov-2"
30707,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.107692308,"with, the, and, to, that, bat, as"
30708,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.107692308,"origin, from, that, and, in, which, their"
30709,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.107692308,"to, indicate, of, in, the, been, that"
30710,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.107692308,"in, the, january, of, huanan, through, market"
30711,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.107692308,"that, a, the, of, and, to, about"
30712,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.107692308,"a, of, and, that, the, with, for"
30713,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.107692308,"from, and, with, sars-cov-2, spike, to, the"
30714,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.107692308,"to, the, have, of, and, suggesting, that"
30715,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.107692308,"a, and, from, to, that, in, bats"
30716,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.107692308,"the, to, be, sars-cov, or, for, and"
30717,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.107692308,"as, a, of, the, it, is, with"
30718,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.107692308,"and, a, of, is, the, for, human"
30719,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.107692308,"in, the, a, was, that, animals, with"
30720,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.107692308,"in, the, market, live, a, of, animals"
30721,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.107692308,"in, the, of, a, suggested, that, were"
30722,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.107692308,"the, that, with, of, or, it, as"
30723,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.107692308,"bats, the, key, be, with, of, could"
30724,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.107692308,"that, to, host, is, a, sars-cov-2, the"
30725,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.107692308,"the, and, also, a, to, ace2, that"
30726,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.107692308,"the, of, to, pathogenicity, can, be, is"
30727,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.107692308,"to, the, and, or, be, for, sars-cov"
30728,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.107692308,"of, be, the, with, bats, could, key"
30729,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.107692308,"the, of, which, suggested, as, was, to"
30730,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.107692308,"the, of, human, to, a, and, as"
30731,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.107692308,"a, of, to, be, with, novel, coronavirus"
30732,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.107692308,"the, and, that, is, bat, sars-, cov-2"
30733,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.107692308,"the, has, a, of, from, bat, and"
30734,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.107692308,"suggested, that, the, in, were, a, of"
30735,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.107692308,"a, overall, to, sars-cov-2,, in, the, that"
30736,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.107692308,"in, of, genome, sequences, and, similar, to"
30737,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.107692308,"that, in, bats, and, to, from, a"
30738,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.107692308,"et, in, to, sars-cov-2, from, and, as"
30739,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.107692308,"suggested, as, the, was, to, which, of"
30740,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.107692308,"a, of, in, that, with, the, to"
30741,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.107692308,"the, rbd, in, to, that, of, but"
30742,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.107692308,"and, a, to, the, of, human, as"
30743,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.107692308,"the, as, a, species, of, to, and"
30744,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.107692308,"of, the, pandemic, that, sars-cov-2, viruses, before"
30745,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.107692308,"that, sars-cov-2, with, has, been, and, to"
30746,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.107692308,"in, the, of, that, a, sars-cov-2, to"
30747,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.107692308,"a, that, the, sars-cov-2, to, host, is"
30748,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.107692308,"of, in, found, a, virus, yunnan, that"
30749,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.107692308,"of, that, virus, a, found, in, with"
30750,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.107692308,"sars-cov-2, and, from, as, et, to, in"
30751,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.107692308,"in, the, and, of, were, to, from"
30752,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.107692308,"the, of, is, to, can, be, pathogenicity"
30753,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.107692308,"the, for, a, of, with, that, and"
30754,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.107692308,"the, of, sars-cov-2, ace2, a, or, that"
30755,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.107692308,"and, also, species, to, may, be, by"
30756,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.107692308,"and, in, been, the, result, of, from"
30757,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.107692308,"of, to, the, in, indicate, that, been"
30758,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.107692308,"to, and, a, furin, cleavage, site, the"
30759,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.107692308,"a, of, the, at, that, or, virus"
30760,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.107692308,"a, the, of, is, virus, in, to"
30761,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.107692308,"to, a, as, genetic, in, bat, species"
30762,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.107692308,"in, two, sars-, the, a, sars-cov-2, to"
30763,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.107692308,"a, the, at, are, by, other, to"
30764,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.107692308,"of, to, the, are, that, is, sars-cov-2."
30765,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.107692308,"that, a, virus, found, in, yunnan, of"
30766,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.107692308,"that, natural, in, the, virus, for, of"
30767,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.107692308,"to, a, the, and, furin, cleavage, site"
30768,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.107692308,"there, are, other, sars-cov-2, to, and, in"
30769,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.107692308,"that, a, virus, found, in, of, with"
30770,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.107692308,"that, the, likely, for, as, to, a"
30771,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.107692308,"the, of, humans, from, intermediate, host, at"
30772,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.107692308,"the, at, was, than, that, in, and"
30773,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.107692308,"of, virus, that, to, the, and, was"
30774,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.107692308,"the, of, more, closely, related, to, than"
30775,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.107692308,"are, a, the, and, in, that, to"
30776,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.107692308,"sars-cov-2, a, and, was, in, zoonotic, or"
30777,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.107692308,"it, that, the, likely, for, sars-cov-2, a"
30778,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.107692308,"this, that, in, and, the, for, of"
30779,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.107692308,"of, in, the, huanan, market, january, through"
30780,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.107692308,"in, from, of, were, to, and, the"
30781,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.107692308,"and, or, was, zoonotic, sars-cov-2, in, a"
30782,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.107692308,"in, with, the, that, sars-cov-2, shows, bat"
30783,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.107692308,"sars-cov-2, ace2, a, of, that, the, or"
30784,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.107692308,"the, that, a, in, overall, to, sars-cov-2,"
30785,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.107692308,"a, from, in, that, the, is, to"
30786,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.107692308,"of, based, on, the, zoonotic, to, in"
30787,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.107692308,"the, of, was, that, virus, to, and"
30788,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.107692308,"the, of, and, have, suggesting, that, to"
30789,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.107692308,"to, and, of, that, similar, viruses, in"
30790,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.107692308,"have, and, in, the, evidence, of, natural"
30791,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.107692308,"the, virus, can, be, in, with, that"
30792,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.107692308,"in, of, the, covid-19, first, were, market"
30793,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.107692308,"to, species, may, be, also, and, by"
30794,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.107692308,"has, a, and, the, of, from, bat"
30795,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.107692308,"the, of, to, a, and, species, as"
30796,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.107692308,"to, from, and, with, the, spike, sars-cov-2"
30797,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.107692308,"that, a, the, of, virus, or, at"
30798,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.107692308,"by, a, other, are, to, at, the"
30799,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.107692308,"the, of, sars-cov-2, that, sars-cov, and, to"
30800,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.107692308,"as, of, the, it, is, with, sars-cov-2"
30801,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.107692308,"is, also, that, sars-cov-2, laboratory, the, genetic"
30802,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.107692308,"it, that, the, with, or, as, of"
30803,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.107692308,"also, of, sars-cov-2, is, an, the, for"
30804,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.107692308,"evidence, the, natural, of, and, have, in"
30805,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.107692308,"sequences, and, that, of, in, which, more"
30806,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.107692308,"the, in, a, that, such, can, naturally"
30807,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.107692308,"the, of, is, and, be, that, to"
30808,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.107692308,"from, a, is, to, in, the, that"
30809,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.107692308,"for, the, that, a, likely, as, to"
30810,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.107692308,"the, it, likely, that, for, sars-cov-2, a"
30811,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.107692308,"in, the, an, and, a, of, sars-cov-2"
30812,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.107692308,"in, also, the, of, a, sars-cov-2, to"
30813,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.107692308,"an, sars-cov-2, to, and, is, viruses, in"
30814,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.107692308,"a, for, the, of, is, and, human"
30815,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.107692308,"the, also, of, sars-cov-2, is, an, for"
30816,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.107692308,"genome, of, and, sequences, in, similar, to"
30817,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.107692308,"is, the, closest, to, that, in, and"
30818,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.107692308,"the, as, that, with, bat, and, to"
30819,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.107692308,"that, the, sars-, cov-2, and, bat, is"
30820,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.107692308,"that, shows, with, the, sars-cov-2, in, bat"
30821,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.107692308,"of, and, that, the, sarbecovirus, bats, pangolins"
30822,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.107692308,"are, a, the, of, with, that, to"
30823,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.107692308,"in, of, the, virus, that, this, for"
30824,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.107692308,"the, of, for, natural, in, virus, that"
30825,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.107692308,"and, the, that, for, of, in, this"
30826,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.107692308,"and, this, for, the, of, that, in"
30827,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.107692308,"the, of, is, and, with, to, an"
30828,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.107692308,"sars-cov-2, to, be, a, of, found, in"
30829,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.107692308,"a, novel, to, coronavirus, be, of, with"
30830,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.107692308,"the, naturally, a, that, such, can, in"
30831,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.107692308,"found, that, the, of, sars-cov-2, is, to"
30832,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.107692308,"a, that, the, also, ace2, and, to"
30833,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.107692308,"in, the, of, that, to, but, rbd"
30834,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.107692308,"viruses, similar, to, in, of, and, that"
30835,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.107692308,"the, of, to, more, closely, related, than"
30836,"Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.107692308,"based, on, the, of, to, in, zoonotic"
30837,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.107526882,"sars-cov-2, ace2, in, a, of, and, that, the, or, for"
30838,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.107526882,"the, are, of, as, viruses, mammals, most, bats, and, other"
30839,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.107526882,"as, in, the, of, and, are, to, for, be, virus"
30840,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.107526882,"in, to, the, viruses, were, more, closely, related, than, other"
30841,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.107526882,"are, for, as, the, of, virus, and, be, in, to"
30842,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.107526882,"the, to, in, a, of, with, that, were, and, market"
30843,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.107526882,"to, the, bats, zoonotic, be, and, of, sequence, that, identity"
30844,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.107526882,"sars-cov-2, of, for, ace2, a, or, that, in, and, the"
30845,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.107526882,"the, these, are, to, and, in, has, been, isolated, may"
30846,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.107526882,"to, other, can, contact, with, of, and, in, cave, bats"
30847,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.107526882,"that, the, zoonotic, and, bats, be, of, sequence, identity, to"
30848,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.107526882,"were, viruses, in, more, closely, related, to, the, than, other"
30849,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.107526882,"bats, are, the, most, mammals, as, of, and, viruses, other"
30850,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.107526882,"that, the, of, were, in, to, with, a, and, market"
30851,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.107526882,"and, of, to, bats, cave, with, other, contact, in, can"
30852,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.107526882,"has, been, in, the, isolated, and, are, to, these, may"
30853,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.107438017,"in, a, to, bat, as, found, coronaviruses, could, and, likely, from, reservoir, species"
30854,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.107438017,"that, a, the, was, or, “that, of, in, not, have, existing, to, live"
30855,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.107438017,"that, the, of, in, was, to, or, live, not, “that, have, a, existing"
30856,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.107438017,"could, from, reservoir, to, a, as, likely, and, coronaviruses, found, in, bat, species"
30857,"Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.107142857,"presence, of, in"
30858,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.107142857,"bats, viruses, of"
30859,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.107142857,"the, from, bats, pangolins, in, of"
30860,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.107142857,"animal, of, are"
30861,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.107142857,"in, of, a"
30862,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.107142857,"animal, in, are"
30863,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.107142857,"coronaviruses, species, of"
30864,"Bats have been reported as being the rich source of 

coronaviruses","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.107142857,"bats, as, the"
30865,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.107142857,"of, southeast, asia, and, china,, the"
30866,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.107142857,"and, to, in"
30867,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.107142857,"in, and, to"
30868,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.107142857,"in, bat, sars-cov-2."
30869,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.107142857,"to, bats, of, species,, and, more"
30870,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.107142857,"to, sars-cov-2, than"
30871,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.107142857,"are, similar, to"
30872,"According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.107142857,"to, sars-cov, sars-like"
30873,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.107142857,"sars-cov-2, is, in"
30874,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.107142857,"virus, to, is"
30875,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.107142857,"in, is, to"
30876,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.107142857,"is, more, in"
30877,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.107142857,"sars-cov-2, is, virus"
30878,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.107142857,"of, to, the, which, seems, virus"
30879,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.107142857,"from, the, bat, of, virus, and"
30880,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.107142857,"of, the, sars-cov-2, have, been, from"
30881,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.107142857,"coronavirus, is, from"
30882,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.107142857,"from, have, been"
30883,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.107142857,"from, it, is"
30884,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.107142857,"in, the, of, to, sars-cov-2, that, new, which, virus"
30885,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.107142857,"coronaviruses, have, a, of, to, and"
30886,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.107142857,"a, of, bat, in, coronaviruses, sars-cov-2"
30887,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.107142857,"the, sars-cov-2, was, in, from, a"
30888,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.107142857,"that, the, a, laboratory, accident, was"
30889,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.107142857,"initial, the, that, sequence, was, a"
30890,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.107142857,"the, from, that, sars-cov-2, a, also"
30891,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.107142857,"that, the, of, bat, viruses, to"
30892,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.107142857,"coronavirus,, to, the, natural, with, as"
30893,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.107142857,"the, identified, as, that, to, bat"
30894,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.107142857,"the, was, found, to, sars-cov, of"
30895,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.107142857,"that, the, of, sars-cov-2, sars-cov, a"
30896,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.107142857,"and, natural, of"
30897,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.107142857,"analysis, of, and, sequences, that, which"
30898,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.107142857,"in, to, of, sars-cov-2, and, compared"
30899,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.107142857,"similar, of, sars-cov-2"
30900,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",Originating from reservoir of bat,0.107142857,"from, bat, of"
30901,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.107142857,"sars-cov-2, including, the, and, that, of"
30902,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.107142857,"are, they, of, the, bats, and"
30903,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.107142857,"have, been, of, and, are, the"
30904,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.107142857,"are, in, and, can, be, to"
30905,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.107142857,"be, a, virus, the, and, an"
30906,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.107142857,"the, of, intermediate"
30907,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.107142857,"the, intermediate, as"
30908,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.107142857,"in, were, intermediate"
30909,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.107142857,"it, is, that, the, covid-19, of"
30910,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.107142857,"the, coronavirus, sars-cov-2"
30911,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.107142857,"sars-cov-2, a, is"
30912,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.107142857,"to, sars-cov-2, a, of, the, and"
30913,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.107142857,"natural, of, sars-"
30914,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.107142857,"of, the, and"
30915,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.107142857,"that, the, and, for, to, sars-cov"
30916,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",zoonotic origins of SARS-CoV-2 by natural evolution,0.107142857,"of, by, natural"
30917,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.107142857,"to, sars-cov-2, from, a, the, with"
30918,"An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.107142857,"of, coronaviruses, species"
30919,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.107142857,"the, of, and, coronaviruses, to, sars-cov-2,"
30920,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.107142857,"the, and, to, coronaviruses, of, sars-cov-2,"
30921,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.107142857,"the, sars-cov, in"
30922,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.107142857,"in, humans, through"
30923,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.107142857,"shows, in, of"
30924,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.107142857,"in, the, bat"
30925,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.107142857,"sars-cov-2, of, the, in, analysis, protein"
30926,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.107142857,"genome, that, the, is, to, of"
30927,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.107142857,"the, and, to, that, bat, of"
30928,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.107142857,"the, for, sars"
30929,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.107142857,"the, that, for"
30930,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.107142857,"to, humans, from, and, with, the"
30931,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.107142857,"coronaviruses, that, to, in, and, from"
30932,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.107142857,"that, the, and, novel, coronavirus, from"
30933,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.107142857,"that, the, with, at, and, to"
30934,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.107142857,"transmitted, to, animal"
30935,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","with the first case being linked to  

a seafood market",0.107142857,"a, to, the, first, being, market"
30936,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.107142857,"of, the, from, in, bats, pangolins"
30937,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.107142857,"of, the, in, is, to, sars-cov-2"
30938,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.107142857,"is, sars-cov-2, even, the, of, from"
30939,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.107142857,"of, sars-cov-2, in, is, the, to"
30940,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.107142857,"a, in, the"
30941,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.107142857,"the, one, and"
30942,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.107142857,"the, that, in"
30943,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.107142857,"the, a, zoonotic"
30944,"The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.107142857,"the, that, zoonotic"
30945,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.107142857,"genetic, in, a, as, to, from"
30946,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.107142857,"animal, are, a, and, in, to"
30947,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.107142857,"sars-cov-2, are, likely, to, a, bat"
30948,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.107142857,"sars-cov-2, a, from, as, to, that"
30949,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.107142857,"the, that, of, and, these, at"
30950,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.107142857,"of, the, that, sars-cov-2, before, into"
30951,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.107142857,"s, from, with"
30952,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.107142857,"zoonotic, from, likely"
30953,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.107142857,"that, a, the, of, sars-cov-2, to"
30954,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.107142857,"the, of, bat, to, viruses, are, a, that, this"
30955,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.107142857,"that, sars-cov-2, the, of, before, into"
30956,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.107142857,"sars-cov-2, from, a, that, in, this"
30957,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.107142857,"the, of, sars-cov-2, are, and, humans"
30958,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.107142857,"sars-cov-2, from, viruses, that, are, and"
30959,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.107142857,"the, by, genomic, of, in, and, that, this, a"
30960,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.107142857,"to, the, of, and, that, animals"
30961,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.107142857,"are, to, that, of, sars-cov-2, and"
30962,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.107142857,"of, cases, the, market, in, that"
30963,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.107142857,"sars-cov-2, that, into, humans, with, the"
30964,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.107142857,"in, the, of, sars-cov-2, at, that"
30965,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.107142857,"a, the, huanan, at, was, market, of, confirmed, by"
30966,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.107142857,"an, animal, a"
30967,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.107142857,"an, in, their"
30968,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.107142857,"nearly, identical, and"
30969,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.107142857,"identical, in, and"
30970,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.107142857,"that, was, the, of, and, to"
30971,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor",0.107142857,"sars-cov-2, to, a"
30972,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.107142857,"that, may, to, sars-cov-2, in, humans"
30973,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.107142857,"that, the, of, sars-cov-2, suggests, from"
30974,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.107142857,"that, to, sars-cov-2, in, and, from"
30975,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.107142857,"in, viruses, are, into, different, and, sars-cov-2, that, the, sars, is, than"
30976,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.107142857,"from, to, a, as, genetic, in"
30977,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.107142857,"the, genome, that, from, to, as"
30978,"with the first case being linked to  

a seafood market","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.107142857,"the, first, being, to, a, market"
30979,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.107142857,"is, a, from, to, that, in"
30980,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.107142857,"the, outbreak, was, and, about, of"
30981,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.107142857,"and, that, is, most, likely, of"
30982,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.107142857,"the, samples, at, market, for, that"
30983,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.107142857,"the, have, an, market, infected, to"
30984,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.107142857,"as, the, was, to, with, and"
30985,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.107142857,"that, the, similarity, and, as, a"
30986,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.107142857,"the, is, seafood"
30987,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.107142857,"and, have, to, a, of, coronaviruses"
30988,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.107142857,"a, species, of, that, to, and"
30989,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.107142857,"sars-cov,, and, the"
30990,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.107142857,"is, coronavirus, from"
30991,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.107142857,"is, through, coronavirus"
30992,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.107142857,"believed, to, be"
30993,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.107142857,"the, a, in"
30994,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.107142857,"in, the, with"
30995,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.107142857,"study, a, the"
30996,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.107142857,"seems, to, the, of, which, virus"
30997,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.107142857,"the, of, cases, market, that, in"
30998,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.107142857,"the, virus, of, which, to, that"
30999,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.107142857,"the, of, to, or, that, this"
31000,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.107142857,"that, been, of, virus, to, the"
31001,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.107142857,"and, bat, pangolin, to, the, that"
31002,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Bats have been reported as being the rich source of 

coronaviruses",0.107142857,"the, as, bats"
31003,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Bats have been reported as being the rich source of 

coronaviruses",0.107142857,"of, been, the"
31004,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Bats have been reported as being the rich source of 

coronaviruses",0.107142857,"bats, the, as"
31005,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.107142857,"the, from, to, humans, and, with"
31006,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.107142857,"from, humans, the, of, sars-cov-2, to"
31007,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.107142857,"to, the, of, and, pangolins, sars-cov-2"
31008,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.107142857,"sars-cov-2, coronavirus, the"
31009,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.107142857,"from, with, the"
31010,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.107142857,"bat, the, sars-cov-2"
31011,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.107142857,"and, the, of, to, that, sars-cov-2"
31012,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.107142857,"to, the, of, and, that, a"
31013,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.107142857,"the, and, to"
31014,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.107142857,"the, and, one"
31015,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.107142857,"and, be, to"
31016,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.107142857,"and, bat, pangolin, the, between, is"
31017,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.107142857,"sequences, and, analysis, that, of, which"
31018,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.107142857,"bats, are, the, and, in, china"
31019,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.107142857,"the, and, have, that, to, humans"
31020,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.107142857,"humans, and, that, to, through, handled"
31021,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.107142857,"bats, are, the, they, of, and"
31022,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.107142857,"is, and, to, the, originated, in"
31023,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.107142857,"in, that, to"
31024,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.107142857,"genetic, been, used"
31025,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.107142857,"in, to, that"
31026,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.107142857,"animal, in, the"
31027,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.107142857,"in, and, that, the, origin, is"
31028,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.107142857,"virus, the, and"
31029,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.107142857,"was, the, of, outbreak, and, about"
31030,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.107142857,"the, sars-cov,, and"
31031,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.107142857,"the, and, bat"
31032,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.107142857,"the, virus, bats"
31033,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.107142857,"to, of, bats, the, and, that"
31034,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.107142857,"that, may, bats"
31035,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.107142857,"the, and, on, for, a, of"
31036,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.107142857,"the, as, reservoir, of, bat, and"
31037,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.107142857,"reservoir, of, the"
31038,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.107142857,"be, the, reservoir"
31039,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.107142857,"the, in, been"
31040,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.107142857,"of, a, at, the, huanan, market, was, confirmed, by"
31041,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.107142857,"not, only, but, also, and, the"
31042,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.107142857,"the, and, also, in, not, but"
31043,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.107142857,"may, have, the, or, in, china"
31044,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.107142857,"for, the, at, market, samples, that"
31045,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.107142857,"only, bat, the, with, that, bats"
31046,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.107142857,"that, the, but, bats, be, of"
31047,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.107142857,"sars-cov-2, of, coronavirus"
31048,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.107142857,"that, to, for, sars-cov, and, the"
31049,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.107142857,"by, and, to, the, sars-cov-2, is"
31050,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.107142857,"is, to, the, that, by, and"
31051,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.107142857,"is, more, of, to, animal, be"
31052,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.107142857,"was, found, the, of, to, sars-cov"
31053,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.107142857,"the, was, as, with, and, to"
31054,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.107142857,"the, of, to, bats, as, for"
31055,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.107142857,"the, of, to, sars-cov, and, bats"
31056,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.107142857,"the, rbd, of, to, was, bats"
31057,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.107142857,"sars-like, to, sars-cov"
31058,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.107142857,"sequence, that, with, the, sars-cov-2, bat"
31059,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.107142857,"the, similarity, of, bat, that, as"
31060,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.107142857,"the, from, human"
31061,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.107142857,"genome, of, the, virus, between, and"
31062,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.107142857,"is, to, the, that, between, and"
31063,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.107142857,"several, to, sars-cov-2"
31064,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.107142857,"most, that, likely, of, and, is"
31065,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.107142857,"has, the, in"
31066,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.107142857,"probably, has, the"
31067,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.107142857,"a, an, animal"
31068,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.107142857,"that, virus, to"
31069,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.107142857,"from, to, virus"
31070,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.107142857,"to, that, human"
31071,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.107142857,"a, that, is"
31072,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.107142857,"is, from, it"
31073,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.107142857,"it, is, a"
31074,"Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.107142857,"also, from, the"
31075,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.107142857,"is, of, related"
31076,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.107142857,"origin, that, in"
31077,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.107142857,"and, in, the"
31078,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.107142857,"have, to, an, the, infected, market"
31079,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.107142857,"sars-cov-2, animal, and"
31080,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.107142857,"evidence, sars-cov-2, a, and, has, that"
31081,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.107142857,"virus, in, has"
31082,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.107142857,"bats, in, virus"
31083,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.107142857,"bats, most, reservoir"
31084,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.107142857,"through, that, and, to, humans, handled"
31085,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.107142857,"of, is, more, to, animal, be"
31086,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.107142857,"virus, that, to"
31087,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.107142857,"the, features, of, and, that, coronavirus"
31088,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.107142857,"this, of, and, by, in, the"
31089,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.107142857,"virus, isolated, in, with, the, of"
31090,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.107142857,"the, between, and, of, genome, virus"
31091,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.107142857,"the, from, with"
31092,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.107142857,"virus, from, to"
31093,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.107142857,"to, from, of, bats, the, with"
31094,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.107142857,"zoonotic, in, coronavirus"
31095,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.107142857,"in, and, as"
31096,"Bats are the second  

largest order of mammals, with over 1,230 species.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.107142857,"are, the, order"
31097,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.107142857,"to, with, coronavirus,, as, the, natural"
31098,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.107142857,"the, that, genome, as, to, from"
31099,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.107142857,"zoonotic, host, to"
31100,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.107142857,"revealed, that, the, and, at, et"
31101,Coronaviruses account for over 30% of the world’s viruses.,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.107142857,"30%, of, the"
31102,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","the close relation  

between SARS coronavirus and 2019-nCoV",0.107142857,"and, the, sars"
31103,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.107142857,"that, the, acid, sequences, of, sars-cov"
31104,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.107142857,"in, the, of, sequence, sars-cov-2, virus"
31105,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.107142857,"sars-cov, from, and, sars-cov-2, isolated, with"
31106,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.107142857,"sars-cov-2, is, a"
31107,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.107142857,"a, from, this, that, sars-cov-2, in"
31108,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.107142857,"that, sars-cov-2, bat"
31109,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.107142857,"that, the, of, coronavirus, likely, from"
31110,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.107142857,"sars-cov-2,, coronaviruses, the, to, of, and"
31111,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.107142857,"that, a, bat, in, genome, of"
31112,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.107142857,"of, the, sars-cov-2, and, are, humans"
31113,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.107142857,"the, and, of"
31114,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.107142857,"and, the, of, are, hosts, sars-cov-2"
31115,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.107142857,"are, to, pangolins, bats, may, be"
31116,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.107142857,"samples, of, which, the, western, huanan"
31117,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Bats are natural hosts of many of the known  

coronaviruses",0.107142857,"bats, the, hosts"
31118,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.107142857,"to, that, sars-cov-2, as, a, from"
31119,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.107142857,"and, species, that, from, a, sequence, in, as, to"
31120,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.107142857,"from, as, and, to, that, sars-cov-2, may, in, a"
31121,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.107142857,"sars-cov-2, and, bat, coronaviruses, high, to"
31122,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.107142857,"that, the, of, sars-cov-2, a, sars-cov"
31123,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.107142857,"the, as, a, that, and, similarity"
31124,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.107142857,"et, revealed, that, the, and, at"
31125,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.107142857,"the, acid, sequences, that, of, sars-cov"
31126,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.107142857,"the, was, to, this, that, of"
31127,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.107142857,"to, this, that, the, but, of"
31128,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.107142857,"be, the, intermediate"
31129,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.107142857,"that, the, of, infect, a, to"
31130,"a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.107142857,"a, coronavirus, with"
31131,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.107142857,"the, of, host"
31132,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.107142857,"of, with, sars-cov-2"
31133,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.107142857,"sars-cov-2, the, with"
31134,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.107142857,"most, of, the, reported, in, chinese"
31135,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.107142857,"was, bats, and"
31136,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.107142857,"sars-cov-2, was, from, a, the, in"
31137,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.107142857,"in, the, of, to, sars-cov-2, a"
31138,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.107142857,"was, in, a, to, sars-cov-2, the"
31139,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.107142857,"a, to, in, sars-cov-2, the, bat"
31140,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.107142857,"the, in, bat"
31141,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.107142857,"the, in, also"
31142,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.107142857,"in, related, sars-cov-2"
31143,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.107142857,"the, origin, that"
31144,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.107142857,"be, the, an"
31145,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.107142857,"sars-cov-2, and, pangolin"
31146,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.107142857,"a, for, the, on, of, and"
31147,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.107142857,"pangolin, in, the, that, for, of"
31148,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.107142857,"even, the, that, of, for, hypothesis"
31149,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.107142857,"of, viruses, in"
31150,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.107142857,"in, the, been"
31151,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.107142857,"the, for, been"
31152,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.107142857,"sars-cov-2, of, a"
31153,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.107142857,"sequence, sars-cov-2, the, of, virus, in"
31154,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.107142857,"in, of, sars-cov-2, found, to, that"
31155,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.107142857,"coronavirus, zoonotic, in"
31156,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.107142857,"viruses, to, the, in, of, and"
31157,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.107142857,"has, to, sars-cov-2"
31158,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.107142857,"genome, similarity, sars-cov-2"
31159,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.107142857,"similarity, sars-cov-2, to"
31160,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.107142857,"sars-cov-2, has, or"
31161,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.107142857,"the, sars-cov-2, cov"
31162,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.107142857,"related, sars-cov-2, in"
31163,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.107142857,"in, the, not"
31164,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.107142857,"the, that, wiv"
31165,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.107142857,"in, into, sars-cov-2, that, the, is"
31166,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.107142857,"the, in, that"
31167,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.107142857,"of, the, human, in, to, with"
31168,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.107142857,"the, to, and, that, a, not"
31169,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.107142857,"the, of, a, in, species, to, that, bats, with, intermediate, direct, years"
31170,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.107142857,"sars-cov-2, a, in, an, host, humans"
31171,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.107142857,"suggests, that, in, pangolin, the, of"
31172,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.107142857,"sars-cov-2, with, bat-"
31173,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.107142857,"virus, has, in"
31174,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.107142857,"genome, of, bat, that, a, in"
31175,"t some virus detected in pangolins 

were capable of infecting humans.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.107142857,"virus, in, of"
31176,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.107142857,"has, a, in, that, bat, of"
31177,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.107142857,"is, to, the"
31178,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.107142857,"the, human, from"
31179,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.107142857,"from, to, the"
31180,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.107142857,"the, identity, with"
31181,"atural  

selection in an animal host before zoonotic  

transfer;","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.107142857,"animal, host, zoonotic"
31182,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.107142857,"shows, that, the, is, group, of"
31183,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.107142857,"sars-cov-2, has, to"
31184,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.107142857,"to, sars-cov-2, of, in, the, has"
31185,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","bats are also important reservoir species for a great 

range of coronaviruses",0.107142857,"species, important, of"
31186,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.107142857,"the, of, sars-cov-2, and, to, an"
31187,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.107142857,"and, sars-cov-2, to, humans, the, in"
31188,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.107142857,"s, with, from"
31189,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.107142857,"that, of, than"
31190,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.107142857,"sars-cov-2, the, cleavage, in, coronaviruses, not"
31191,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.107142857,"such, as, and, it, to, the, of, that, sars-cov-2"
31192,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.107142857,"the, in, of, that, sars-cov-2, also"
31193,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.107142857,"that, hosts, for, sars-cov-2, in, with"
31194,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.107142857,"the, in, that, hosts, for, sars-cov-2"
31195,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.107142857,"also, that, the, sars-cov-2, and, larger"
31196,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.107142857,"in, to, sars-cov-2, and, the, humans"
31197,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.107142857,"the, in, and, that, sars-cov-2, with"
31198,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.107142857,"that, the, between, sars-cov-2, and, than"
31199,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.107142857,"found, that, are, to, and, the"
31200,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.107142857,"to, the, and, be, possible, for"
31201,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.107142857,"to, host, zoonotic"
31202,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.107142857,"a, the, an"
31203,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.107142857,"that, was, a, laboratory, accident, the"
31204,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.107142857,"the, of, to, that, and, a"
31205,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.107142857,"in, the, of, to, with, human"
31206,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.107142857,"to, and, the, were, market., in"
31207,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.107142857,"coronavirus, in, with"
31208,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.107142857,"to, the, with, a, from, sars-cov-2"
31209,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.107142857,"evidence, that, sars-cov-2, has, a, and"
31210,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.107142857,"of, the, a, furin, cleavage, site"
31211,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.107142857,"the, of, sars-cov-2, with, coronaviruses, to"
31212,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.107142857,"and, from, in, to, that, the, of, bats, sars-cov-2"
31213,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.107142857,"the, of, that, it, is, covid-19"
31214,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.107142857,"the, sars-cov-2, from, even, of, is"
31215,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.107142857,"or, of, and, the, in, bats"
31216,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Bats are the second  

largest order of mammals, with over 1,230 species.",0.107142857,"of, the, with"
31217,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Bats are the second  

largest order of mammals, with over 1,230 species.",0.107142857,"the, with, of"
31218,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.107142857,"them, have, and, the, ability, to, reservoir, species, including"
31219,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",Coronaviruses account for over 30% of the world’s viruses.,0.107142857,"of, the, 30%"
31220,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.107142857,"of, viruses, bats"
31221,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.107142857,"animal, and, the"
31222,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.107142857,"the, and, for"
31223,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.107142857,"for, the, virus, and, in, to"
31224,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.107142857,"the, sars, for"
31225,"bats are also important reservoir species for a great 

range of coronaviruses","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.107142857,"important, species, of"
31226,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.107142857,"the, to, bat"
31227,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.107142857,"the, of, asia, and, southeast, china,"
31228,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.107142857,"and, by, this, the, in, of"
31229,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.107142857,"the, viruses, of, bat, that, to"
31230,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.107142857,"the, that, to, infect, a, of"
31231,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.107142857,"a, in, the, events, that, to"
31232,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.107142857,"the, that, same, can, in, distinct"
31233,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.107142857,"a, viruses, are, to, bat, that, the, of, this"
31234,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.107142857,"of, the, presented, in, and, that, a, with, viruses"
31235,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.107142857,"similarity, sars-cov-2, which, is, the, to"
31236,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.107142857,"to, a, genome, which, was, in"
31237,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.107142857,"by, the, closely, related, to, of"
31238,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","This suggests that the BANAL series may be able to directly infect  

humans.",0.107142857,"to, that, banal"
31239,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.107142857,"that, to, human"
31240,"This suggests that the BANAL series may be able to directly infect  

humans.","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.107142857,"that, banal, to"
31241,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.107142857,"viruses, that, to"
31242,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.107142857,"a, of, the, furin, cleavage, site"
31243,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.107142857,"as, in, and"
31244,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.107142857,"was, and, bats"
31245,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.107142857,"is, sars-cov-2, related"
31246,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.107142857,"sars-cov-2, be, the, to, in, virus"
31247,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.107142857,"the, to, sars-cov-2, in, a, bat"
31248,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.107142857,"the, sars-cov-2, to, a, bat, and"
31249,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.107142857,"the, zoonotic, that"
31250,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.107142857,"that, several, the"
31251,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.107142857,"with, the, of, a, from, and"
31252,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.107142857,"from, at, with, the, of, on"
31253,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.107142857,"a, sequence, and, from, species, as, to, that, in"
31254,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.107142857,"of, and, a, related, to, that, in, as, human"
31255,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.107142857,"that, direct, of, bats, to, intermediate, a, in, with, species, the, years"
31256,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.107142857,"the, and, also, a, in, to, ace2, receptors, that, coronaviruses, direct, of"
31257,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.107142857,"the, of, that, in, a, could, use, sars, receptor, human, and, to"
31258,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.107142857,"and, at, the, that, or, supply, chain,, of, in, this, from, a"
31259,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.107142857,"of, samples, the, western, huanan, which"
31260,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.107142857,"animal, to, a, are, and, in"
31261,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.107142857,"that, the, in, events, a, to"
31262,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.107142857,"these, and, that, the, at, of"
31263,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.107142857,"that, are, the, these, associated, with, in, of, and"
31264,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.107142857,"the, of, at, that, is, in"
31265,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.107142857,"this, that, from, in, the, supply, chain,, a, or, at, and, of"
31266,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.107142857,"the, with, that, sars-cov-2, into, humans"
31267,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","expended to make the simple point 

that COVID-19 had a natural origin.",0.107142857,"covid-19, to, the"
31268,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","expended to make the simple point 

that COVID-19 had a natural origin.",0.107142857,"to, that, the"
31269,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.107142857,"in, that, coronaviruses, from, to, and"
31270,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.107142857,"that, sars-cov-2, to, from, and, in"
31271,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.107142857,"coronaviruses, to, sars-cov-2, in, including, that"
31272,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.107142857,"to, that, bats, and, pangolins, sars-cov-2"
31273,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.107142857,"the, also, from"
31274,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.107142857,"the, as, from"
31275,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.107142857,"humans, an, host, a, in, sars-cov-2"
31276,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.107142857,"sequence, with, bat, that, the, sars-cov-2"
31277,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.107142857,"is, that, or"
31278,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.107142857,"this, of, to, the, that, or"
31279,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.107142857,"this, is, sars-cov-2, to, the, that"
31280,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.107142857,"coronavirus, is, through"
31281,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.107142857,"of, sars-cov-2, coronavirus"
31282,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.107142857,"a, it, is"
31283,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.107142857,"of, is, related"
31284,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.107142857,"of, sars-cov-2, a"
31285,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.107142857,"is, related, sars-cov-2"
31286,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.107142857,"that, is, from"
31287,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.107142857,"bats, as, the, to, of, for"
31288,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.107142857,"bat, that, the, of, as, similarity"
31289,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.107142857,"the, pangolin, in, that, for, of"
31290,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.107142857,"coronaviruses, that, to, sars-cov-2, in, including"
31291,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.107142857,"that, a, the, of, sars-cov-2, is"
31292,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.107142857,"sars-cov-2, also, in, of, that, the"
31293,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.107142857,"these, sars-cov-, the, and, or, pangolins"
31294,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.107142857,"the, of, that, and, including, sars-cov-2"
31295,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.107142857,"the, sars-cov-2, and, of, is, that"
31296,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.107142857,"the, in, sars-cov-2, not, cleavage, coronaviruses"
31297,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.107142857,"to, have, been, in, contact, animals"
31298,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.107142857,"have, been, in, from, is, and"
31299,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.107142857,"that, was, a, the, sequence, initial"
31300,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.107142857,"the, not, to, that, and, a"
31301,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.107142857,"the, a, of, that, most, bat"
31302,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.107142857,"in, a, found, novel, coronavirus, that"
31303,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.107142857,"the, to, a, that, receptor, and, could, human, sars, in, of, use"
31304,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.107142857,"bats, the, to, sars-cov, of, and"
31305,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.107142857,"the, that, from, bats,, to, and"
31306,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",The COVID-19 most likely developed from bat origin coronaviruses,0.107142857,"the, origin, likely"
31307,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",The COVID-19 most likely developed from bat origin coronaviruses,0.107142857,"the, from, covid-19"
31308,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",The COVID-19 most likely developed from bat origin coronaviruses,0.107142857,"bat, from, coronaviruses"
31309,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.107142857,"from, the, bat, origin, of, these"
31310,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.107142857,"are, can, and, be, in, to"
31311,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.107142857,"to, be, and"
31312,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.107142857,"to, and, in"
31313,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.107142857,"most, animal, in"
31314,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.107142857,"the, seafood, is"
31315,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.107142857,"in, the, to"
31316,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.107142857,"in, to, the"
31317,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.107142857,"in, the, of, chinese, most, reported"
31318,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.107142857,"in, which, of"
31319,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.107142857,"the, and, to, of, is, bat"
31320,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.107142857,"the, animals, that, to, and, of"
31321,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.107142857,"to, the, viruses, in, and, of"
31322,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.107142857,"and, to, the, of, that, have, been, in, a"
31323,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.107142857,"that, the, in, same, distinct, can"
31324,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.107142857,"animals, to, in, have, been, contact"
31325,"The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.107142857,"the, that, several"
31326,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.107142857,"that, is, or"
31327,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.107142857,"the, or, of, bats, in, and"
31328,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.107142857,"bats, the, is, and, be, to"
31329,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.107142857,"and, to, bats, of, more, species,"
31330,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.107142857,"bats, are, as, to, a, bat"
31331,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.107142857,"virus, in, bats"
31332,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.107142857,"bats, are, to, be, pangolins, may"
31333,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.107142857,"sars-cov-2, the, of, have, been, from"
31334,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.107142857,"is, and, from, in, have, been"
31335,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.107142857,"virus, with, the, isolated, in, of"
31336,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.107142857,"the, from, at, of, on, with"
31337,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","t some virus detected in pangolins 

were capable of infecting humans.",0.107142857,"of, were, in"
31338,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","t some virus detected in pangolins 

were capable of infecting humans.",0.107142857,"in, virus, of"
31339,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.107142857,"the, in, by"
31340,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.107142857,"their, in, an"
31341,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.107142857,"of, in, which"
31342,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.107142857,"the, in, china, may, have, or"
31343,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.",0.107142857,"evidence, that, viruses"
31344,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.107142857,"the, of, and, that, this, a"
31345,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.107142857,"this, the, of"
31346,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.107142857,"the, and, not, only, but, also"
31347,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.107142857,"the, reservoir, to, species, have, and, ability, them, including"
31348,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.107142857,"reservoir, of, not, but, the, a"
31349,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.107142857,"also, a, zoonotic, including, the, and"
31350,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.107142857,"identified, that, to, bat, as, the"
31351,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.107142857,"a, that, species, of, to, and"
31352,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.107142857,"that, the, of, most, a, bat"
31353,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.107142857,"the, from, that, to, bats,, and"
31354,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.107142857,"the, of, has, a, as, and"
31355,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.107142857,"virus, is, sars-cov-2"
31356,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.107142857,"of, the, and, zoonotic, to, virus"
31357,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.107142857,"origin, of, sars-"
31358,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.107142857,"a, origin, of, by, at, the"
31359,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.107142857,"to, the, of, by, a, virus"
31360,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.107142857,"are, in, animal"
31361,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.107142857,"the, in, animal"
31362,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.107142857,"the, not, in"
31363,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.107142857,"coronavirus, with, in"
31364,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.107142857,"in, most, animal"
31365,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.107142857,"that, to, host, is, a, sars-cov-2"
31366,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.107142857,"in, humans, that, sars-cov-2, may, to"
31367,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.107142857,"to, suggest, that, may, as, sars-cov-2"
31368,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.107142857,"not, a, of, but, the, reservoir"
31369,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.107142857,"the, been, for"
31370,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.107142857,"sars-cov-2, a, and, from, as, to, that, may, in"
31371,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.107142857,"such, as, and, the, of, to, it, that, sars-cov-2"
31372,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.107142857,"to, the, have, been, in, of, and, that, a"
31373,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.107142857,"this, the, as, intermediate, for, sars-cov-2"
31374,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.107142857,"was, the, sars-cov-2"
31375,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.107142857,"likely, from, zoonotic"
31376,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.107142857,"the, was, cov"
31377,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.107142857,"sars-cov-2, has, been"
31378,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.107142857,"sars-cov-2, the, cov"
31379,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.107142857,"bat, to, the"
31380,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.107142857,"was, the, cov"
31381,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.107142857,"the, hypothesis, that, for, even, of"
31382,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.107142857,"the, has, as, a, of, and"
31383,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.107142857,"the, sars-cov-2, and, to, is, by"
31384,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.107142857,"to, from, sars-cov-2"
31385,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.107142857,"from, that, sars-cov-2, and, are, viruses"
31386,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.107142857,"and, nearly, identical"
31387,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.107142857,"that, and, to"
31388,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.107142857,"that, sars-cov-2, and"
31389,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.107142857,"to, that, viruses"
31390,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.107142857,"and, to, that, sars-cov-2, ratg13, are"
31391,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.107142857,"that, sars-cov-2, ratg13"
31392,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.107142857,"and, from, to, that, are, sars-cov-2"
31393,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.107142857,"compared, and, sars-cov-2, to, in, of"
31394,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.107142857,"that, are, to, sars-cov-2, and, of"
31395,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.107142857,"nucleotide, sequences, of, sars-cov-2, and, ratg13"
31396,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.107142857,"sars-cov-2, and, ratg13, coronaviruses, to, of"
31397,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.107142857,"with, sars-cov-2, of"
31398,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.107142857,"sars-cov-2, similarity, genome"
31399,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.107142857,"the, wiv, that"
31400,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.107142857,"provides, evidence, that"
31401,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.107142857,"that, the, and, to, is, by"
31402,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.107142857,"the, between, and, is, to, that"
31403,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.107142857,"to, sars-cov-2, of, the, with, coronaviruses"
31404,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.107142857,"of, sars-cov-2, similar"
31405,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.107142857,"of, sars-cov-2, nucleotide, and, sequences, ratg13"
31406,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.107142857,"the, that, is, a, has, in"
31407,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.107142857,"the, that, of, are, associated, with, and, these, in"
31408,"Bats are natural hosts of many of the known  

coronaviruses","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.107142857,"bats, hosts, the"
31409,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.107142857,"also, that, sars-cov-2, from, a, the"
31410,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.107142857,"the, to, that, sars-cov-2, and, a"
31411,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.107142857,"a, to, sars-cov-2, the, bat, and"
31412,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.107142857,"the, genome, of, that, is, to"
31413,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.107142857,"of, the, shows, that, is, group"
31414,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.107142857,"the, closely, related, to, by, of"
31415,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.107142857,"is, that, bats, the, to, a"
31416,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.107142857,"most, reservoir, bats"
31417,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.107142857,"a, bat, to, bats, are, as"
31418,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.107142857,"a, that, the, is, to, bats"
31419,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.107142857,"the, a, to, that, bat, are"
31420,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.107142857,"that, a, the, of, and, to"
31421,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.107142857,"and, the, of, bat, to, a, that, which, virus"
31422,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.107142857,"a, of, the, at, by, origin"
31423,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.107142857,"was, in, a, which, to, genome"
31424,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.107142857,"a, similarity, of, in, which, to"
31425,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.107142857,"to, similarity, is, which, sars-cov-2, the"
31426,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.107142857,"of, similarity, to, a, which, in"
31427,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.107142857,"sars-cov-2, in, that, with, hosts, for"
31428,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.107142857,"are, the, have, been, of, and"
31429,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.107142857,"sars-cov-2, and, pangolin, to, the, that"
31430,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.107142857,"a, of, the, this, by, that, genomic, and, in"
31431,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.107142857,"that, the, features, of, coronavirus, and"
31432,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.107142857,"this, a, that, the, of, and"
31433,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.107142857,"the, to, as"
31434,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.107142857,"we, the, sars-cov-2"
31435,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.107142857,"that, and, sars-cov-2, the, in, with"
31436,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.107142857,"and, the, of, viruses, a, with, presented, that, in"
31437,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.107142857,"sars-cov-2, to, than"
31438,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.107142857,"is, sars-cov-2, to"
31439,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.107142857,"sars-cov-2, bat, pangolin"
31440,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.107142857,"the, to, be, possible, for, and"
31441,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.107142857,"the, sars-cov-, pangolins, and, these, or"
31442,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.107142857,"be, in, the, that, or, for"
31443,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.107142857,"the, with, bat, that, only, bats"
31444,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.107142857,"are, the, that, bats, hosts, for"
31445,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.107142857,"the, novel, coronavirus, that, from, and"
31446,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.107142857,"from, the, of, suggests, that, sars-cov-2"
31447,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.107142857,"the, of, coronavirus, from, that, likely"
31448,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.107142857,"the, to, that, pangolin, and, bat"
31449,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.107142857,"in, to, is, the, originated, and"
31450,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.107142857,"the, sars-cov-2, to, is, that, this"
31451,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.107142857,"that, pangolin, to, and, the, sars-cov-2"
31452,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.107142857,"the, viruses, that, are, sars, in, is, different, than, and, into, sars-cov-2"
31453,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.107142857,"the, is, and, that, origin, in"
31454,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.107142857,"into, the, that, is, in, sars-cov-2"
31455,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.107142857,"the, bat, pangolin, of, sars-, cov"
31456,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.107142857,"the, of, bat, cov, pangolin, sars-"
31457,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.107142857,"bat, the, of"
31458,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.107142857,"sars-cov-2, in, that, the, hosts, for"
31459,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.107142857,"that, and, sars-cov-2, than, the, between"
31460,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.107142857,"the, probably, has"
31461,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.107142857,"sars-cov-2, that, bat"
31462,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.107142857,"sars-cov-2, that, ratg13"
31463,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.107142857,"than, that, of"
31464,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.107142857,"bat, sars-cov-2, pangolin"
31465,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.107142857,"that, the, sars-cov-2, and, is, we"
31466,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.107142857,"sars-cov-2, also, and, larger, that, the"
31467,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.107142857,"that, bats, may"
31468,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.107142857,"have, in, that"
31469,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.107142857,"pangolins, to, and, the, of, sars-cov-2"
31470,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.107142857,"that, to, sars-cov-2, bats, and, pangolins"
31471,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.107142857,"suggest, that, as, may, to, sars-cov-2"
31472,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.107142857,"the, of, and, from, bat, virus"
31473,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.107142857,"of, the, bat, origin, from, these"
31474,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.107142857,"found, the, and, are, to, that"
31475,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.107142857,"sars-cov-2, to, a, are, likely, bat"
31476,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.107142857,"that, and, sars-cov-2"
31477,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.107142857,"sars-cov-2, of, the, and, with, to"
31478,"a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.107142857,"bat-, with, sars-cov-2"
31479,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.107142857,"that, sars-cov-2, bat-sl-cov-2"
31480,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.107142857,"sars-cov-2, of, the, emergence, and, in"
31481,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.107142857,"sars-cov-2, and, sars-cov, with, isolated, from"
31482,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.107142857,"sars-cov-2, is, bat-sl-cov-2"
31483,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.107142857,"and, identical, in"
31484,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.107142857,"in, the, and, to, sars-cov-2, are"
31485,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.107142857,"and, in, to, the, are, sars-cov-2"
31486,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.107142857,"suggests, that, of, in, pangolin, the"
31487,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.107142857,"the, to, at, with, of, and"
31488,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.107142857,"bats, the, was, to, rbd, of"
31489,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.107142857,"sars-cov-2, of, which, to, virus, that, in, new, the"
31490,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.107142857,"the, of, that, sars-cov-2, at, in"
31491,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.107142857,"sars-cov-2, the, for"
31492,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.107142857,"intermediate, as, this, for, the, sars-cov-2"
31493,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.107142857,"sars-cov-2, pangolin, the"
31494,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.107142857,"of, be, the, that, but, bats"
31495,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.107142857,"the, of, that, but, to, this"
31496,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.107142857,"a, of, the, by, to, virus"
31497,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.107142857,"bat-sl-cov-2, that, sars-cov-2"
31498,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.107142857,"bat-sl-cov-2, is, sars-cov-2"
31499,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.107142857,"the, be, intermediate"
31500,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.107142857,"a, the, virus, and, be, an"
31501,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.107142857,"a, study, the"
31502,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.107142857,"the, virus, and"
31503,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.107142857,"the, an, be"
31504,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.107142857,"the, a, an"
31505,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.107142857,"the, is, that, of, in, at"
31506,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.107142857,"the, is, has, a, that, in"
31507,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.107142857,"the, in, that, or, be, for"
31508,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.107142857,"sars-cov-2, a, of, in, bat, coronaviruses"
31509,The COVID-19 most likely developed from bat origin coronaviruses,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.107142857,"from, bat, coronaviruses"
31510,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.107142857,"a, also, zoonotic, and, the, including"
31511,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.107142857,"origin, of, be, to, that, sars-cov-2"
31512,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.107142857,"found, in, of, that, sars-cov-2, to"
31513,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.107142857,"that, a, novel, found, in, coronavirus"
31514,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.107142857,"in, of, as, a, that, to, human, and, related"
31515,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.107142857,"to, sars-cov-2, from, of, in, bats, the, and, that"
31516,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.107142857,"sars-cov-2, from, that, are, to, and"
31517,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.107142857,"the, and, not, but, also, in"
31518,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.107142857,"that, a, bat, in, has, of"
31519,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.107142857,"the, of, a, in, to, that, and, direct, also, ace2, receptors, coronaviruses"
31520,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.107142857,"that, are, the, to, a, bat"
31521,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.107142857,"the, analysis, sars-cov-2, protein, in, of"
31522,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.107142857,"the, virus, to, sars-cov-2, be, in"
31523,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.107142857,"and, in, the, emergence, of, sars-cov-2"
31524,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.107142857,"sars-cov-2, and, coronaviruses, bat, high, to"
31525,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.107142857,"coronaviruses, to, of, sars-cov-2, and, ratg13"
31526,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.106796117,"the, has, been, as, a, of, that, to, humans, by, such"
31527,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.106796117,"from, the, a, virus, with, bat, and, in, of, isolated, yunnan"
31528,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.106796117,"similarities, sars-cov-2, of, the, to, related, pangolin, in, but, found, that"
31529,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.106796117,"found, in, the, of, similarities, that, sars-cov-2, related, to, but, pangolin"
31530,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.106796117,"a, as, animal, in, for, the, or, of, and, also, species"
31531,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.106796117,"and, an, from, to, samples, at, the, in, of, a, was"
31532,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.106796117,"a, positive, samples, collected, and, were, to, of, which, in, the"
31533,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.106796117,"a, and, with, the, of, virus, isolated, from, bat, in, yunnan"
31534,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.106796117,"also, in, a, of, animal, species, and, the, as, or, for"
31535,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.106796117,"a, from, at, market, in, china, that, the, of, were, bats"
31536,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.106796117,"in, the, of, an, was, a, at, samples, from, to, and"
31537,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.106796117,"in, a, of, to, the, collected, samples, which, positive, and, were"
31538,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.106796117,"that, to, such, as, the, humans, by, a, of, has, been"
31539,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.106796117,"that, were, from, bats, in, the, china, market, a, at, of"
31540,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.106666667,"sars-cov-2, to, a, of, an, and, the, ability"
31541,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.106666667,"are, that, an, to, cells, and, is, in"
31542,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.106666667,"as, also, the, of, and, their, in, to"
31543,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.106666667,"a, for, the, as, of, is, and, with"
31544,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.106666667,"to, in, the, that, for, ace2, is, of"
31545,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.106666667,"a, of, the, also, are, that, to, virus"
31546,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.106666667,"and, hubei, to, seafood, market, in, a, animal"
31547,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.106666667,"sars-cov-2, of, to, a, an, and, ability, the"
31548,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.106666667,"that, by, a, of, and, are, the, sars-cov-2"
31549,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.106666667,"in, with, the, clustering, and, that, sars-cov-2, of"
31550,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.106666667,"are, is, and, in, that, to, an, cells"
31551,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.106666667,"that, the, market, in, to, animals, evidence, a"
31552,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.106666667,"that, the, virus, in, and, animals, at, a"
31553,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.106666667,"evidence, the, that, in, a, to, animals, market"
31554,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.106666667,"also, as, the, of, and, in, their, to"
31555,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.106666667,"with, the, and, to, that, of, bat, pangolin"
31556,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.106666667,"the, of, on, is, by, to, virus,, that"
31557,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.106666667,"a, at, the, and, in, animals, virus, that"
31558,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.106666667,"the, in, a, virus, to, through, that, genetic"
31559,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.106666667,"from, and, to, the, that, have, in, a"
31560,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.106666667,"in, the, and, to, is, of, are, they"
31561,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.106666667,"and, in, to, the, of, is, bats, are"
31562,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.106666667,"a, for, as, the, of, is, and, with"
31563,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.106666667,"of, and, intermediate, species, that, likely, humans, to"
31564,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.106666667,"and, it, be, likely, that, of, sars-cov-2, by"
31565,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.106666667,"intermediate, and, it, to, by, of, that, sars-cov-2"
31566,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.106666667,"the, of, and, virus, in, human, this, with"
31567,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.106666667,"bats, natural, of, and, a, to, as, human"
31568,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.106666667,"a, sequence, and, coronaviruses, bat, to, that, in"
31569,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.106666667,"and, bat, coronaviruses, that, a, sequence, in, to"
31570,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.106666667,"a, et, from, in, that, is, to, bats"
31571,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.106666667,"with, to, at, the, in, of, a, was"
31572,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.106666667,"of, in, that, the, to, virus, closely, related"
31573,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.106666667,"and, the, it, its, for, of, from, a"
31574,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.106666667,"found, in, bats, to, that, of, sars-cov-2, sequences"
31575,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.106666667,"on, the, of, that, is, virus,, to, by"
31576,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.106666667,"through, genetic, that, the, virus, in, to, a"
31577,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.106666667,"the, of, and, from, a, taken, with, to"
31578,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.106666667,"from, and, to, was, by, the, of, a"
31579,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.106666667,"in, the, of, that, closely, related, to, virus"
31580,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.106666667,"humans, and, likely, that, of, to, intermediate, species"
31581,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.106666667,"the, taken, from, a, and, to, of, with"
31582,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.106666667,"a, samples, and, were, to, of, in, the"
31583,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.106666667,"to, a, seafood, and, animal, market, in, hubei"
31584,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.106666667,"a, in, the, with, was, to, of, at"
31585,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.106666667,"in, the, of, a, samples, were, to, and"
31586,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.106666667,"and, it, likely, that, of, sars-cov-2, be, by"
31587,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.106666667,"the, of, a, for, it, its, from, and"
31588,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.106666667,"to, that, the, of, is, likely, natural, sars-cov-2"
31589,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.106666667,"for, the, of, is, in, that, to, ace2"
31590,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.106666667,"viruses, to, the, in, of, and, that, a"
31591,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.106666667,"the, of, that, viruses, in, a, and, to"
31592,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.106666667,"a, in, china, that, the, to, of, bats"
31593,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.106666667,"hosts, of, and, a, to, that, such, as"
31594,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.106666667,"are, also, a, the, of, virus, that, to"
31595,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.106666667,"have, that, the, in, and, to, from, a"
31596,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.106666667,"and, it, that, of, sars-cov-2, to, intermediate, by"
31597,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.106666667,"the, by, was, from, a, and, to, of"
31598,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.106666667,"that, of, bats, to, found, in, sars-cov-2, sequences"
31599,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.106666667,"is, a, from, et, to, that, in, bats"
31600,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.106666667,"to, the, in, bats, of, that, a, china"
31601,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.106666667,"a, of, the, by, that, sars-cov-2, and, are"
31602,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.106666667,"and, to, that, the, of, are, hosts, sars-cov-2"
31603,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.106666667,"the, of, to, with, that, pangolin, and, bat"
31604,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.106666667,"are, they, in, to, is, of, the, and"
31605,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.106666667,"and, a, to, bats, natural, of, human, as"
31606,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.106666667,"as, a, of, that, to, hosts, such, and"
31607,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.106666667,"are, in, to, is, of, the, bats, and"
31608,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.106666667,"the, of, sars-cov-2, to, is, likely, natural, that"
31609,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.106666667,"that, of, to, and, are, the, hosts, sars-cov-2"
31610,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.106557377,"civets,, and, to, this, accounted, for, by, the, of, that, sars-cov-2, in, a"
31611,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.106557377,"the, and, accounted, for, of, a, to, that, in, this, sars-cov-2, civets,, by"
31612,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.106382979,"a, large, of, in, bats"
31613,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.106382979,"of, a, large, in, bats"
31614,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.106382979,"the, of, in, from, bats"
31615,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.106382979,"to, sars-cov-2, a, and, pangolin"
31616,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.106382979,"coronaviruses, and, which, in, sars-cov-2"
31617,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.106382979,"are, a, and, in, to"
31618,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.106382979,"bat, and, human, sars-cov-2, a"
31619,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.106382979,"in, but, animal, a, of"
31620,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.106382979,"recent, the, reservoirs, and, of"
31621,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.106382979,"and, coronaviruses, particularly, the, of"
31622,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.106382979,"to, the, and, reservoir, be"
31623,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.106382979,"that, virus, and, bats, of"
31624,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.106382979,"that, virus, of, coronavirus, and"
31625,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.106382979,"sars-cov-2, and, sars-cov, of, in"
31626,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.106382979,"and, in, to, of, sars-cov-2"
31627,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.106382979,"sequences, and, of, were, more"
31628,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.106382979,"genetic, bats, and, from, infected"
31629,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.106382979,"and, more, of, species, by"
31630,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.106382979,"of, bats, were, from, and"
31631,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.106382979,"the, similar, to, sars-like, sars-cov"
31632,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.106382979,"within, and, similar, are, the"
31633,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.106382979,"to, spillover, of, and, the"
31634,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.106382979,"the, was, to, of, as"
31635,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.106382979,"the, of, sars-cov-2, as, a"
31636,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.106382979,"sars-cov-2, is, naturally, of, the"
31637,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.106382979,"a, virus, from, the, is"
31638,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.106382979,"the, in, is, also, from"
31639,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.106382979,"is, also, from, in, the"
31640,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.106382979,"the, are, to, and, of"
31641,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.106382979,"are, the, a, of, and"
31642,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.106382979,"genetic, that, virus, and, a"
31643,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.106382979,"the, to, that, have, sars-cov-2"
31644,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.106382979,"that, the, sars-cov-2, to, host"
31645,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.106382979,"the, of, identical, a, sars-cov-2"
31646,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.106382979,"found, that, the, of, to"
31647,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.106382979,"based, on, genome, results, and"
31648,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.106382979,"the, showed, suggesting, that, might"
31649,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.106382979,"the, virus, human, to, and"
31650,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.106382979,"that, the, to, sars-cov-2, covid-19"
31651,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.106382979,"more, sequences, were, of, and"
31652,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.106382979,"observed, similar, sequences, of, and"
31653,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.106382979,"of, between, and, including, sars-cov-2"
31654,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.106382979,"and, with, the, in, of"
31655,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.106382979,"of, and, bat, in, the"
31656,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.106382979,"have, that, sars-cov-2, to, the"
31657,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.106382979,"of, sars-cov-2, between, including, and"
31658,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.106382979,"have, that, of, to, and"
31659,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.106382979,"that, be, the, sars-cov-2, its"
31660,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.106382979,"the, that, has, in, of"
31661,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.106382979,"that, has, the, bats, of"
31662,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.106382979,"a, in, the, that, human"
31663,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.106382979,"viruses, are, coronaviruses,, the, of"
31664,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.106382979,"more, than, of, the, and"
31665,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.106382979,"and, have, most, bats, of"
31666,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.106382979,"other, are, and, the, of"
31667,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.106382979,"the, was, to, that, in"
31668,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.106382979,"to, that, similarity, the, virus"
31669,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.106382979,"of, to, the, seems, close"
31670,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.106382979,"sars-cov-2, humans, to, the, for"
31671,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.106382979,"of, in, the, as, china"
31672,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.106382979,"that, the, market, in, to"
31673,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.106382979,"the, in, on, that, of"
31674,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.106382979,"that, were, to, in, china,"
31675,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.106382979,"that, the, of, this, likely"
31676,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.106382979,"to, the, of, and, spillover"
31677,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.106382979,"of, the, is, a, animal"
31678,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.106382979,"transmission, to, be, of, and"
31679,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.106382979,"the, has, that, of, and"
31680,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.106382979,"that, the, most, of, and"
31681,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.106382979,"the, species, into, to, and"
31682,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.106382979,"the, that, sars-cov, and, to"
31683,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.106382979,"from, the, was, at, wuhan"
31684,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.106382979,"to, is, from, was, the"
31685,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.106382979,"the, from, rhinolophus, which, in"
31686,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.106382979,"is, to, in, the, which"
31687,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.106382979,"the, sars-cov-2, to, is, a"
31688,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.106382979,"a, with, to, the, sars-cov-2"
31689,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.106382979,"to, and, the, species, into"
31690,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.106382979,"including, the, and, coronaviruses, of"
31691,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.106382979,"of, the, in, is, sars-cov-2"
31692,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.106382979,"is, that, sars-cov-2, the, in"
31693,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.106382979,"of, sars-cov-2, in, is, the"
31694,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.106382979,"that, to, sars-cov, and, the"
31695,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.106382979,"is, to, the, that, and"
31696,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.106382979,"bat, and, the, sars-cov-2, with"
31697,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.106382979,"of, sars-cov-2, to, with, that"
31698,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.106382979,"the, that, for, of, natural"
31699,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.106382979,"the, that, in, any, to"
31700,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.106382979,"of, the, to, can, animal"
31701,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","with the first case being linked to  

a seafood market",0.106382979,"a, seafood, market, the, to"
31702,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.106382979,"the, from, in, to, humans"
31703,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.106382979,"bats, humans, found, in, the"
31704,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.106382979,"to, sars-cov-2, even, in, humans"
31705,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.106382979,"the, that, and, in, one"
31706,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.106382979,"hypothesis, the, that, was, virus"
31707,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.106382979,"a, the, that, it, not"
31708,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.106382979,"sars-cov-2, to, in, animal, host"
31709,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.106382979,"sars-cov-2, a, between, and, an"
31710,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.106382979,"humans, that, of, sars-cov-2, to"
31711,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.106382979,"to, the, sars-cov-2, from, as"
31712,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.106382979,"the, from, a, to, of"
31713,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.106382979,"the, sars-cov-2, through, and, spread"
31714,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.106382979,"only, the, sars-cov-2, that, are"
31715,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.106382979,"at, the, was, from, wuhan"
31716,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.106382979,"that, from, and, was, the"
31717,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.106382979,"the, nucleotide, of, from, and"
31718,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.106382979,"the, of, that, bat, ratg13"
31719,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.106382979,"sars-cov-2, from, pangolins, and, of"
31720,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.106382979,"are, the, of, coronaviruses,, viruses"
31721,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.106382979,"sars-cov-2, a, that, to, the"
31722,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.106382979,"that, the, of, and, lineage"
31723,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.106382979,"the, a, huanan, market, to"
31724,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.106382979,"with, the, of, a, and"
31725,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.106382979,"a, was, confirmed, the, by"
31726,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.106382979,"confirmed, the, of, et, virus"
31727,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.106382979,"from, the, was, a, virus, by, of, sample, taken, at"
31728,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.106382979,"in, from, of, and, the"
31729,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.106382979,"in, the, closely, related, to"
31730,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.106382979,"sampled, to, in, the, human"
31731,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.106382979,"was, that, the, sars-cov-2, and"
31732,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.106382979,"in, the, that, sars-cov-2, was"
31733,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.106382979,"in, to, two, from, humans"
31734,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.106382979,"of, zoonotic, sars-cov-2, to, in"
31735,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.106382979,"at, zoonotic, and, in, to"
31736,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.106382979,"the, of, and, more, than"
31737,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.106382979,"in, a, but, of, animal"
31738,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.106382979,"a, it, that, the, enzyme, receptor, for, to, is, by"
31739,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.106382979,"is, to, and, that, in"
31740,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.106382979,"that, a, sars-cov-2, evidence, is"
31741,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.106382979,"sars-cov-2, in, a, that, or"
31742,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.106382979,"on, the, as, that, with"
31743,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.106382979,"there, that, the, sars-cov-2, before"
31744,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.106382979,"the, animals, wet, as, with, on, that, infected, were, by"
31745,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.106382979,"that, with, the, sars-cov-2, collected"
31746,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.106382979,"the, that, sars-cov-2, with, at"
31747,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.106382979,"two, humans, from, in, to"
31748,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.106382979,"the, from, two, in, genome"
31749,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.106382979,"the, spillover, to, a, in"
31750,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.106382979,"the, that, to, a, genome"
31751,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.106382979,"the, evidence, that, a, in"
31752,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.106382979,"the, likely, that, was, for, of, in, this, from, a"
31753,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.106382979,"the, of, raccoon, and, were, that, virus, a, found, in"
31754,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.106382979,"that, in, to, from, a"
31755,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.106382979,"is, evidence, that, sars-cov-2, a"
31756,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.106382979,"of, from, such, as, and"
31757,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.106382979,"the, on, that, with, as"
31758,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.106382979,"that, with, the, to, as"
31759,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.106382979,"samples, and, were, the, huanan"
31760,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.106382979,"of, to, that, have, and"
31761,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.106382979,"have, and, of, to, that"
31762,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.106382979,"host, of, and, the, in"
31763,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.106382979,"that, the, and, to, a"
31764,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.106382979,"the, genome, coronavirus, to, bat"
31765,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.106382979,"the, was, a, and, to"
31766,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.106382979,"as, of, the, was, to"
31767,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.106382979,"the, of, published, in, journal"
31768,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.106382979,"a, study, the, of, with"
31769,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.106382979,"the, of, in, market, that"
31770,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.106382979,"the, in, of, to, that"
31771,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.106382979,"close, to, the, of, seems"
31772,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.106382979,"of, cases, in, the, market"
31773,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.106382979,"that, in, who, exposed, market"
31774,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.106382979,"in, of, to, the, those"
31775,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.106382979,"of, the, in, that, group"
31776,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.106382979,"this, the, in, that, than"
31777,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.106382979,"the, to, in, of, than"
31778,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.106382979,"of, cases, the, market, in"
31779,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.106382979,"early, in, wuhan, the, of"
31780,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.106382979,"published, in, the, journal, of"
31781,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.106382979,"of, the, virus, and, coronavirus"
31782,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.106382979,"the, of, from, and, which"
31783,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.106382979,"the, is, of, to, virus"
31784,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.106382979,"and, sars-cov-2, to, pangolin, a"
31785,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.106382979,"is, the, to, was, from"
31786,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.106382979,"and, that, from, the, was"
31787,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.106382979,"the, virus, and, available, was"
31788,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Bats have been reported as being the rich source of 

coronaviruses",0.106382979,"the, have, been, bats, of"
31789,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.106382979,"he, to, similar, sars-cov-2, the"
31790,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.106382979,"and, by, virus, the, of"
31791,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.106382979,"to, the, sars-cov-2, has, and"
31792,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.106382979,"of, and, by, a, the"
31793,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.106382979,"the, of, pangolin, intermediate, hosts"
31794,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.106382979,"pangolin, to, the, is, of"
31795,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.106382979,"to, the, of, and, hosts"
31796,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.106382979,"a, was, the, and, to"
31797,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.106382979,"genetic, from, bats, infected, and"
31798,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.106382979,"genetic, and, a, virus, that"
31799,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.106382979,"is, the, virus, was, of"
31800,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.106382979,"has, been, that, bats,, to"
31801,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.106382979,"is, of, the, virus, was"
31802,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.106382979,"that, a, of, virus, the"
31803,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.106382979,"the, and, virus, to, that"
31804,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.106382979,"in, the, that, to, virus"
31805,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.106382979,"in, the, that, to, and"
31806,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.106382979,"that, to, and, is, in"
31807,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.106382979,"to, in, the, that, is"
31808,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.106382979,"the, that, to, origin, virus"
31809,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.106382979,"to, that, the, and, origin"
31810,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.106382979,"in, the, of, and, reported"
31811,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.106382979,"of, and, that, bats, virus"
31812,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.106382979,"to, be, of, and, bats"
31813,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.106382979,"and, to, be, the, reservoir"
31814,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.106382979,"the, shares, identity, with, human"
31815,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.106382979,"however,, the, and, in, not"
31816,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.106382979,"however,, the, in, not, that"
31817,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.106382979,"were, sold, live, in, the"
31818,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.106382979,"at, the, that, hosts, for"
31819,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.106382979,"be, the, that, from, for"
31820,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.106382979,"of, the, genomic, that, coronavirus"
31821,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.106382979,"of, sars-cov-2, the, to, human"
31822,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.106382979,"that, sars-cov-2, to, the, host"
31823,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.106382979,"a, the, was, confirmed, by"
31824,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.106382979,"enzyme, receptor, that, it, to, the, by, a, is, for"
31825,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.106382979,"a, the, to, sars-cov-2, ace2"
31826,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.106382979,"the, that, to, which, and"
31827,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.106382979,"the, sars-like, similar, to, sars-cov"
31828,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.106382979,"the, genome, more, for, than"
31829,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.106382979,"previous, the, for, of, sars-cov"
31830,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.106382979,"can, be, the, of, bat"
31831,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.106382979,"bat, to, the, of, sars-cov-2."
31832,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.106382979,"the, of, that, from, bat"
31833,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.106382979,"the, that, of, human, are"
31834,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.106382979,"of, virus, the, confirmed, et"
31835,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.106382979,"from, a, spike, in, the"
31836,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.106382979,"bats, most, have, of, and"
31837,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.106382979,"a, the, it, is, to"
31838,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.106382979,"is, from, a, the, virus"
31839,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.106382979,"a, is, the, for, to"
31840,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.106382979,"of, the, from, in, bats"
31841,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.106382979,"of, the, in, is, to"
31842,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.106382979,"is, also, from, the, in"
31843,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.106382979,"found, in, the, and, are"
31844,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.106382979,"virus, the, to, and, human"
31845,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.106382979,"the, to, have, been, in"
31846,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.106382979,"the, may, have, to, an"
31847,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.106382979,"the, is, that, sars-cov-2, and"
31848,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.106382979,"is, that, sars-cov-2, the, from"
31849,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.106382979,"more, of, species, by, and"
31850,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.106382979,"and, sars-cov-2, is, to, of"
31851,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.106382979,"to, that, sars-cov-2, of, humans"
31852,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.106382979,"sars-cov-2, and, very, to, of"
31853,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.106382979,"of, and, that, virus, coronavirus"
31854,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.106382979,"the, of, lineage, and, that"
31855,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.106382979,"the, virus, of, and, coronavirus"
31856,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.106382979,"available, virus, and, was, the"
31857,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.106382979,"with, the, and, in, of"
31858,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.106382979,"of, by, the, and, virus"
31859,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.106382979,"of, was, ace2, the, in"
31860,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.106382979,"virus, in, genome, of, with"
31861,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.106382979,"to, be, with, of, bats"
31862,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.106382979,"of, virus, with, to, the"
31863,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.106382979,"of, the, genomic, coronavirus, that"
31864,"insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.106382979,"from, of, such, as, and"
31865,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.106382979,"the, sars, and, related, to"
31866,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.106382979,"the, sars-cov-2, from, a, et"
31867,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.106382979,"that, the, a, laboratory, and"
31868,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.106382979,"sars-cov-2, animal, host, to, in"
31869,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.106382979,"the, to, humans, from, in"
31870,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.106382979,"the, to, in, from, a"
31871,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.106382979,"that, the, a, and, to"
31872,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.106382979,"the, in, to, seafood, market"
31873,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.106382979,"market, who, in, that, exposed"
31874,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.106382979,"in, that, identified, and, first"
31875,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.106382979,"sars-cov, and, sars-cov-2, in, of"
31876,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.106382979,"of, the, sequence, and, sars-cov-2"
31877,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.106382979,"sars-cov-2, has, a, and, in"
31878,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.106382979,"of, sars-cov-2, has, the, a"
31879,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.106382979,"the, pangolin, of, intermediate, hosts"
31880,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.106382979,"in, most, these, were, intermediate"
31881,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.106382979,"the, a, and, of, with"
31882,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.106382979,"the, of, may, intermediate, to"
31883,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.106382979,"was, et, to, the, of"
31884,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.106382979,"has, been, that, and, a"
31885,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.106382979,"the, of, that, to, a"
31886,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.106382979,"a, to, of, in, the"
31887,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.106382979,"to, the, genome, in, that"
31888,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.106382979,"may, a, of, that, the"
31889,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.106382979,"suggest, that, may, be, the"
31890,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.106382979,"a, of, the, is, sars-cov-2"
31891,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.106382979,"is, that, sars-cov-2, a, the"
31892,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.106382979,"a, of, sars-cov-2, is, the"
31893,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.106382979,"on, to, in, the, huanan"
31894,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.106382979,"the, of, et, was, to"
31895,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.106382979,"and, linked, to, of, the"
31896,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.106382979,"the, et, sars-cov-2, from, a"
31897,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.106382979,"the, from, a, in, to"
31898,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.106382979,"the, was, in, a, of"
31899,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.106382979,"of, the, at, that, origin"
31900,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.106382979,"on, the, of, that, in"
31901,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.106382979,"the, that, a, and, pangolin"
31902,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.106382979,"as, a, of, the, sars-cov-2"
31903,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.106382979,"the, of, sars-cov-2, and, a"
31904,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.106382979,"sars-cov-2, a, the, of, from"
31905,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.106382979,"hypothesis, that, the, virus, was"
31906,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.106382979,"analysis, that, the, of, closely"
31907,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.106382979,"the, analysis, that, to, which"
31908,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.106382979,"which, was, found, in, the"
31909,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.106382979,"a, in, the, bat, and"
31910,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.106382979,"of, and, the, in, bat"
31911,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.106382979,"and, a, of, in, the"
31912,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.106382979,"the, reservoirs, of, and, recent"
31913,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.106382979,"the, of, and, sars-cov-2, to"
31914,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.106382979,"of, and, viruses, in, the"
31915,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.106382979,"to, and, of, viruses, in"
31916,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.106382979,"were, from, bats, of, and"
31917,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.106382979,"the, from, bats,, and, a"
31918,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.106382979,"the, in, pangolins, possible, for"
31919,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.106382979,"the, of, may, to, as"
31920,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.106382979,"the, covid-19, to, that, sars-cov-2"
31921,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.106382979,"the, that, sars-cov-2, there, before"
31922,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.106382979,"the, of, coronaviruses, sars-cov-2, or"
31923,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.106382979,"viruses, of, the, sars-cov-2, is"
31924,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.106382979,"the, sars-cov-2, to, and, by"
31925,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.106382979,"in, the, that, to, any"
31926,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.106382979,"in, the, that, sars-cov-2, to"
31927,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.106382979,"the, that, is, not, virus"
31928,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.106382979,"the, for, and, not, been"
31929,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.106382979,"and, sars-cov-2, coronaviruses, in, which"
31930,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.106382979,"the, which, in, rhinolophus, from"
31931,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.106382979,"nucleotide, and, from, the, of"
31932,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.106382979,"the, in, genome, two, from"
31933,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.106382979,"the, which, of, and, from"
31934,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.106382979,"the, in, with, which, were"
31935,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.106382979,"genome, identity, with, and, sars-cov-2"
31936,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.106382979,"sars-cov-2, in, the, with, which"
31937,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.106382979,"the, of, sars-cov-2, with, genome"
31938,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.106382979,"genome, of, virus, in, with"
31939,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.106382979,"the, origin, of, that, animal"
31940,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.106382979,"a, is, the, that, not"
31941,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.106382979,"sequence, sars-cov-2, and, the, of"
31942,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.106382979,"in, to, of, the, has"
31943,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.106382979,"of, the, high, degree, homology"
31944,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.106382979,"to, the, sars-cov-2, as, from"
31945,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.106382979,"to, has, sars-cov-2, the, and"
31946,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.106382979,"sars-cov-2, also, to, the, in"
31947,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","bats are also important reservoir species for a great 

range of coronaviruses",0.106382979,"bats, are, reservoir, of, for"
31948,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.106382979,"and, in, the, of, from"
31949,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.106382979,"of, to, the, those, in"
31950,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.106382979,"in, humans, the, and, sars-cov-2"
31951,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.106382979,"amino, acid, the, be, sars-cov-2"
31952,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.106382979,"is, the, most, to, in"
31953,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.106382979,"a, in, the, human, for"
31954,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.106382979,"that, sars-cov-2, in, animal, species"
31955,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.106382979,"suggest, that, the, may, be"
31956,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.106382979,"in, the, are, found, and"
31957,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.106382979,"have, been, able, to, the"
31958,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.106382979,"a, the, sars-cov-2, ace2, to"
31959,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.106382979,"the, sars-cov-2, amino, acid, be"
31960,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.106382979,"sars-cov-2, through, and, spread, the"
31961,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.106382979,"to, by, and, the, sars-cov-2"
31962,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.106382979,"the, to, for, is, also"
31963,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.106382979,"from, the, a, to, spillover"
31964,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.106382979,"the, that, and, a, laboratory"
31965,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.106382979,"the, seafood, market, in, to"
31966,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.106382979,"the, in, live, were, sold"
31967,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.106382979,"at, the, and, in, to"
31968,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.106382979,"to, in, sars-cov-2, the, and"
31969,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.106382979,"and, sars-cov-2, in, the, to"
31970,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.106382979,"in, the, of, at, that"
31971,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.106382979,"that, the, in, from, market"
31972,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.106382979,"from, in, sars-cov-2, the, of"
31973,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.106382979,"is, the, virus, sars-cov-2, covid-19"
31974,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.106382979,"zoonotic, of, sars-cov-2, in, to"
31975,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.106382979,"the, in, a, to, spillover"
31976,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.106382979,"to, natural, the, of, is"
31977,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.106382979,"the, natural, is, to, of"
31978,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.106382979,"in, bats, south, and, china"
31979,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.106382979,"the, in, bats, and, of"
31980,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.106382979,"species, bats, and, in, the"
31981,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.106382979,"bat, to, as, sars-cov-2, the"
31982,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.106382979,"in, to, coronaviruses, the, bat, most, discovered, and, closely, related"
31983,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.106382979,"bat, the, sars-cov-2, that, are"
31984,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.106382979,"the, to, and, related, sars"
31985,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.106382979,"the, in, closely, viruses, to"
31986,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.106382979,"and, to, of, in, the"
31987,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.106382979,"within, the, and, are, similar"
31988,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.106382979,"a, of, by, the, and"
31989,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.106382979,"the, viruses, in, and, of"
31990,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.106382979,"the, viruses, closely, to, in"
31991,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.106382979,"the, in, that, bat, as"
31992,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.106382979,"of, from, with, a, sars-cov-2"
31993,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.106382979,"to, have, appear, with, of"
31994,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.106382979,"he, similar, to, the, sars-cov-2"
31995,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.106382979,"the, sars-cov-2, with, and, to"
31996,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.106382979,"the, of, that, have, to"
31997,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.106382979,"a, the, to, which, and"
31998,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.106382979,"the, two, and, a, viruses"
31999,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.106382979,"the, and, is, which, same"
32000,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.106382979,"the, and, is, viruses, same"
32001,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.106382979,"is, the, to, sars-cov-2,, less"
32002,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.106382979,"is, sars-cov-2, the, virus, in"
32003,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.106382979,"the, in, is, most, to"
32004,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.106382979,"is, sars-cov-2, the, covid-19, virus"
32005,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.106382979,"the, a, and, in, bat"
32006,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.106382979,"recombination, and, in, the, sars-cov-2"
32007,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.106382979,"that, first, and, identified, in"
32008,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.106382979,"in, sars-cov-2, and, the, humans"
32009,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.106382979,"when, the, in, that, sars-cov-2"
32010,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.106382979,"with, the, and, to, of"
32011,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.106382979,"a, the, to, huanan, market"
32012,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.106382979,"a, the, of, and, in, raccoon, found, virus, that, were"
32013,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.106382979,"the, of, a, to, live, animal, in, markets,, markets, and, shenzhen, market, were, at, palm"
32014,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.106382979,"the, coronaviruses, discovered, to, most, closely, related, bat, in, and"
32015,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.106382979,"of, a, virus, at, the, was, by, from, sample, taken"
32016,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.106382979,"the, on, wet, animals, that, infected, with, were, as, by"
32017,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.106382979,"samples, were, the, huanan, and"
32018,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.106382979,"to, the, huanan, in, on"
32019,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.106382979,"to, is, a, and, the"
32020,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.106382979,"the, of, evidence, is, a"
32021,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.106382979,"the, and, are, that, to"
32022,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.106382979,"at, zoonotic, in, and, to"
32023,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.106382979,"to, a, that, and, the"
32024,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.106382979,"this, to, that, the, and"
32025,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.106382979,"the, that, are, to, a"
32026,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.106382979,"the, and, one, that, in"
32027,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.106382979,"that, the, of, human, are"
32028,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.106382979,"is, that, one, of, the"
32029,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.106382979,"in, a, of, the, likely, that, was, this, from, for"
32030,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.106382979,"to, the, sars-cov-2, for, humans"
32031,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.106382979,"the, to, that, sars-cov-2, virus"
32032,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.106382979,"a, that, the, virus, to"
32033,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.106382979,"the, that, sars-cov-2, a, with"
32034,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","unnatural origin of SARS-CoV-2, but these people are 

simply wrong",0.106382979,"these, are, of, sars-cov-2,, but"
32035,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.106382979,"bats, in, and, south, china"
32036,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.106382979,"to, from, rhinolophus, found, in"
32037,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.106382979,"the, in, and, to, a"
32038,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.106382979,"has, a, sars-cov-2, and, in"
32039,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.106382979,"in, a, sars-cov-2, origin, zoonotic"
32040,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.106382979,"the, that, with, sars-cov-2, collected"
32041,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.106382979,"that, sars-cov-2, the, virus, genome,"
32042,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.106382979,"that, sars-cov-2, is, or, laboratory"
32043,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.106382979,"a, natural, of, likely, on"
32044,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.106382979,"that, a, of, sars-cov-2, is"
32045,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.106382979,"the, virus, is, not, that"
32046,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.106382979,"is, that, the, virus, from"
32047,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.106382979,"the, to, it, that, of"
32048,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.106382979,"that, the, of, to, as"
32049,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.106382979,"not, a, that, the, it"
32050,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.106382979,"human, in, to, sampled, the"
32051,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.106382979,"the, spike, in, from, a"
32052,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.106382979,"the, that, not, is, a"
32053,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.106382979,"the, from, that, to, which"
32054,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.106382979,"that, it, is, to, the"
32055,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.106382979,"sars-cov-2, virus, that, to, the"
32056,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.106382979,"the, of, sars-cov-2, identical, a"
32057,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.106382979,"the, of, sars-cov-2, or, coronaviruses"
32058,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.106382979,"of, from, a, with, sars-cov-2"
32059,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.106382979,"however,, the, of, sars-cov-2, from"
32060,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.106382979,"including, coronaviruses, the, of, and"
32061,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.106382979,"however,, the, and, not, in"
32062,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.106382979,"that, in, the, however,, not"
32063,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.106382979,"the, analysis, of, that, closely"
32064,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.106382979,"cov, the, bats, more, than"
32065,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.106382979,"that, the, and, to, which"
32066,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.106382979,"the, analysis, which, that, to"
32067,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.106382979,"from, to, the, which, that"
32068,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.106382979,"the, high, degree, of, homology"
32069,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.106382979,"the, of, bats, in, and"
32070,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.106382979,"transmitted, to, are, and, in"
32071,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.106382979,"in, these, were, most, intermediate"
32072,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.106382979,"the, to, be, is, in"
32073,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.106382979,"in, of, the, which, was"
32074,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.106382979,"is, to, the, that, it"
32075,"Bats have been reported as being the rich source of 

coronaviruses","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.106382979,"bats, have, been, the, of"
32076,"bats are also important reservoir species for a great 

range of coronaviruses","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.106382979,"bats, are, reservoir, for, of"
32077,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.106382979,"the, which, were, in, with"
32078,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.106382979,"in, the, same, with, which"
32079,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.106382979,"in, of, patients, were, with"
32080,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.106382979,"in, the, of, that, has"
32081,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.106382979,"the, have, been, in, to"
32082,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.106382979,"that, the, has, to, of"
32083,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.106382979,"to, of, appear, have, with"
32084,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.106382979,"the, of, to, it, that"
32085,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.106382979,"the, in, of, as, china"
32086,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.106382979,"the, is, that, of, one"
32087,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.106382979,"in, the, of, host, and"
32088,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.106382979,"to, be, of, and, transmission"
32089,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.106382979,"and, bats, be, of, to"
32090,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.106382979,"with, bats, to, be, of"
32091,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.106382979,"of, with, other, to, be"
32092,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.106382979,"the, humans, bats, in, found"
32093,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.106382979,"the, species, bats, in, and"
32094,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.106382979,"a, of, the, shenzhen, market, palm, at, animal, and, live, markets, were, in, to, markets,"
32095,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.106382979,"is, the, of, viruses, sars-cov-2"
32096,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.106382979,"that, a, of, and, the"
32097,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.106382979,"the, to, is, also, for"
32098,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.106382979,"covid-19, a, the, from, for"
32099,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.106382979,"has, been, to, that, bats,"
32100,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.106382979,"human, and, sars-cov-2, bat, a"
32101,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.106382979,"that, a, and, has, been"
32102,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.106382979,"and, identity, with, sars-cov-2, genome"
32103,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.106382979,"that, sars-cov-2, a, has, been"
32104,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.106382979,"and, of, the, for, to"
32105,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.106382979,"of, likely, natural, on, a"
32106,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.106382979,"the, that, at, origin, of"
32107,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.106382979,"that, are, the, origin, of"
32108,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.106382979,"that, to, an, intermediate, host"
32109,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.106382979,"sars-cov-2, to, humans, even, in"
32110,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.106382979,"has, a, sars-cov-2, the, of"
32111,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.106382979,"sars-cov-2, the, not, that, of"
32112,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.106382979,"been, the, of, sars-cov-2, has"
32113,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.106382979,"the, for, not, been, and"
32114,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.106382979,"sars-cov-2, in, animal, species, that"
32115,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.106382979,"the, of, is, that, virus"
32116,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.106382979,"that, sars-cov-2, is, laboratory, or"
32117,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.106382979,"and, ratg13, an, to, 2"
32118,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.106382979,"to, other, be, with, of"
32119,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.106382979,"of, with, to, the, sars-cov-2"
32120,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.106382979,"sequences, and, similar, of, observed"
32121,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.106382979,"and, of, similar, ratg13, bat"
32122,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.106382979,"ace2, the, was, in, of"
32123,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.106382979,"in, to, the, sars-cov-2, also"
32124,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.106382979,"the, is, of, natural, to"
32125,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.106382979,"and, this, the, that, to"
32126,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.106382979,"the, its, be, that, sars-cov-2"
32127,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.106382979,"the, pangolin, and, that, a"
32128,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.106382979,"the, to, sars-cov-2, bat, and"
32129,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.106382979,"a, bat, sars-cov-2, using, the"
32130,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.106382979,"the, genome, more, than, for"
32131,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.106382979,"a, for, sars-cov-2, to, that"
32132,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.106382979,"to, and, a, the, which"
32133,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.106382979,"a, virus, that, to, the"
32134,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.106382979,"the, using, sars-cov-2, a, bat"
32135,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.106382979,"to, found, in, rhinolophus, from"
32136,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.106382979,"a, to, for, the, is"
32137,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.106382979,"2, an, to, ratg13, and"
32138,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.106382979,"of, similar, to, and, sars-cov-2."
32139,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.106382979,"suggest, that, sars-cov-2, the, with"
32140,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.106382979,"the, of, sars-cov-2, and, intermediate"
32141,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.106382979,"been, the, able, to, have"
32142,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.106382979,"group, of, the, in, that"
32143,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.106382979,"two, viruses, and, a, the"
32144,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.106382979,"sequences, in, the, of, and"
32145,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.106382979,"the, sars-cov-2, of, is, naturally"
32146,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.106382979,"in, the, genome, that, to"
32147,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.106382979,"pangolins, possible, for, the, in"
32148,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.106382979,"that, sars-cov-2, only, are, the"
32149,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.106382979,"the, at, for, that, hosts"
32150,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.106382979,"the, that, are, sars-cov-2, bat"
32151,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.106382979,"the, more, than, cov, bats"
32152,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.106382979,"the, of, that, this, likely"
32153,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.106382979,"is, the, to, which, in"
32154,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.106382979,"the, which, in, with, sars-cov-2"
32155,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.106382979,"the, same, in, with, which"
32156,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.106382979,"this, the, than, in, that"
32157,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.106382979,"in, that, the, when, sars-cov-2"
32158,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.106382979,"this, sars-cov-2, the, that, in"
32159,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.106382979,"and, the, which, is, same"
32160,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.106382979,"the, has, with, that, bat"
32161,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.106382979,"suggest, that, with, the, sars-cov-2"
32162,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.106382979,"sars-cov-2, the, this, that, of"
32163,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.106382979,"of, the, are, that, origin"
32164,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.106382979,"the, that, are, of, sars-cov-2"
32165,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.106382979,"viruses, and, the, is, same"
32166,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.106382979,"the, sars-cov-2, with, and, bat"
32167,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.106382979,"the, to, of, hosts, and"
32168,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.106382979,"the, to, and, that, origin"
32169,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.106382979,"of, in, the, wuhan, early"
32170,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.106382979,"of, the, in, and, sequences"
32171,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.106382979,"that, the, bat, ratg13, of"
32172,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.106382979,"the, of, with, sars-cov-2, genome"
32173,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.106382979,"with, and, to, sars-cov-2, the"
32174,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.106382979,"to, with, sars-cov-2, the, and"
32175,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.106382979,"of, and, that, the, in"
32176,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.106382979,"recombination, in, sars-cov-2, the, and"
32177,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.106382979,"the, in, and, from, a"
32178,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.106382979,"the, a, from, bats,, and"
32179,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.106382979,"the, of, previous, for, sars-cov"
32180,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.106382979,"of, and, are, a, the"
32181,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.106382979,"of, the, virus, in, and"
32182,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.106382979,"and, the, of, virus, in"
32183,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.106382979,"the, and, in, that, of"
32184,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.106382979,"the, that, with, sars-cov-2, at"
32185,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.106382979,"at, the, with, sars-cov-2, that"
32186,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.106382979,"the, of, and, that, an"
32187,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.106382979,"the, of, bat, can, be"
32188,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.106382979,"and, this, the, in, of"
32189,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.106382979,"the, of, from, however,, sars-cov-2"
32190,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.106382979,"the, that, sars-cov-2, from, possibly"
32191,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.106382979,"that, the, of, suggesting, to"
32192,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.106382979,"the, of, in, that, at"
32193,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.106382979,"that, of, the, virus, is"
32194,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.106382979,"the, to, that, similarity, virus"
32195,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.106382979,"virus, that, the, sars-cov-2, genome,"
32196,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.106382979,"the, to, from, of, a"
32197,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.106382979,"the, that, was, bat, as"
32198,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.106382979,"that, the, bat, in, as"
32199,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.106382979,"the, in, those, that, animal"
32200,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.106382979,"that, likely, sars-cov-2, is, to"
32201,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.106382979,"of, and, the, intermediate, sars-cov-2"
32202,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.106382979,"sars-cov-2, an, a, between, and"
32203,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.106382979,"evidence, the, that, in, a"
32204,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.106382979,"the, from, for, that, be"
32205,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.106382979,"the, covid-19, for, a, from"
32206,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.106382979,"that, sars-cov-2, from, a, in"
32207,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.106382979,"the, that, sars-cov-2, possibly, from"
32208,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.106382979,"of, sars-cov-2, with, that, to"
32209,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.106382979,"sars-cov-2, a, origin, in, zoonotic"
32210,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.106382979,"of, patients, were, with, in"
32211,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.106382979,"that, for, sars-cov-2, to, a"
32212,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.106382979,"found, in, the, which, was"
32213,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.106382979,"sars-cov-2, the, of, that, to"
32214,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.106382979,"the, animal, of, can, to"
32215,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.106382979,"less, to, sars-cov-2,, the, is"
32216,"unnatural origin of SARS-CoV-2, but these people are 

simply wrong","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.106382979,"of, sars-cov-2,, but, these, are"
32217,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.106382979,"to, viruses, in, and, of"
32218,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.106382979,"similar, of, and, bat, ratg13"
32219,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.106382979,"and, bat, ratg13, to, of"
32220,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.106382979,"the, as, that, with, to"
32221,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.106382979,"the, have, an, to, may"
32222,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.106382979,"as, to, the, of, may"
32223,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.106382979,"the, of, to, suggesting, that"
32224,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.106382979,"the, of, coronaviruses, and, particularly"
32225,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.106382979,"the, of, to, bat, sars-cov-2."
32226,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.106382979,"very, and, of, sars-cov-2, to"
32227,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.106382979,"to, and, of, ratg13, bat"
32228,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.10619469,"to, the, bats, as, reservoirs, be, and, a, of, three, coronaviruses, or"
32229,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.10619469,"in, the, of, from, found, that, to, species, a, coronavirus, is, direct"
32230,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.10619469,"that, direct, of, from, to, is, a, coronavirus, found, in, species, the"
32231,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.10619469,"coronaviruses, and, a, to, the, bats, be, reservoirs, of, three, or, as"
32232,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.106060606,"in, a, of, and, that, the, or"
32233,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.106060606,"a, pangolin, and, sars-cov-2, other, to, in"
32234,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.106060606,"in, viruses, are, and, sars-cov-2, bat, pangolin"
32235,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.106060606,"a, was, the, of, sars-cov-2, is, to"
32236,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.106060606,"sars-cov-2, in, a, of, the, with, as"
32237,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.106060606,"the, sars-cov-2, have, to, of, genetic, coronaviruses"
32238,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.106060606,"sars-cov-2, the, genetic, of, have, to, coronaviruses"
32239,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.106060606,"is, a, which, the, bat, in, spike"
32240,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.106060606,"that, of, intermediate, in, pangolin, analysis, sequences"
32241,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.106060606,"the, of, and, sequence, in, with, to"
32242,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.106060606,"sars-cov, and, to, the, of, sars-cov-2, in"
32243,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.106060606,"in, the, of, as, a, that, human"
32244,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.106060606,"the, to, bats, in, of, is, be"
32245,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.106060606,"the, that, to, a, also, and, coronavirus"
32246,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.106060606,"from, to, the, of, bats, hosts, sars-cov-2"
32247,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.106060606,"and, from, species, can, as, to, that"
32248,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.106060606,"as, and, the, to, can, that, natural"
32249,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.106060606,"the, that, are, with, and, in, at"
32250,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.106060606,"the, coronavirus, a, demonstrating, that, in, coronaviruses"
32251,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.106060606,"are, the, sars-cov-2, to, be, of, and"
32252,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.106060606,"bats, the, of, is, be, in, to"
32253,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.106060606,"in, from, an, animal, and, a, sars-cov-2"
32254,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.106060606,"are, an, sars-cov-2, to, from, and, in"
32255,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.106060606,"a, as, reservoir, bat, high, and, certain"
32256,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.106060606,"a, of, to, the, that, from, as"
32257,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.106060606,"and, from, closely, related, of, bats, sars-cov-2"
32258,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.106060606,"the, to, that, sars-cov-2, of, bat, are"
32259,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.106060606,"and, the, of, which, that, by, a"
32260,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.106060606,"the, in, of, that, sars-cov-2, we, this"
32261,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.106060606,"of, to, the, are, that, sold, market"
32262,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.106060606,"and, the, huanan, be, that, of, sars-cov-2"
32263,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.106060606,"the, closely, related, in, a, to, that"
32264,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.106060606,"in, a, of, the, this, is, market"
32265,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.106060606,"a, at, the, of, and, in, is"
32266,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.106060606,"the, of, and, a, in, this, with"
32267,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.106060606,"sars-cov-2, from, an, animal, a, and, in"
32268,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.106060606,"that, the, of, multiple, in, a, to"
32269,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.106060606,"sars-cov-2, from, an, to, are, and, in"
32270,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.106060606,"to, the, that, as, a, of, from"
32271,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.106060606,"the, market, sold, that, are, to, of"
32272,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.106060606,"this, is, a, of, the, market, in"
32273,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.106060606,"that, is, covid-19, in, from, a, to"
32274,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.106060606,"the, first, covid-19, to, that, was, a"
32275,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.106060606,"a, analysis, of, to, that, the, virus"
32276,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.106060606,"have, that, are, the, for, a, of"
32277,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.106060606,"is, a, and, of, at, the, in"
32278,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.106060606,"a, of, data, that, the, and, virus"
32279,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.106060606,"in, a, to, that, covid-19, is, from"
32280,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.106060606,"that, from, a, in, evidence, to, humans."
32281,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.106060606,"a, of, the, was, is, to, sars-cov-2"
32282,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.106060606,"is, that, sars-cov-2, a, the, pandemic, of"
32283,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.106060606,"we, the, was, to, by, animals, a"
32284,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.106060606,"a, to, the, that, covid-19, was, first"
32285,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.106060606,"of, the, and, with, high, to, in"
32286,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.106060606,"the, of, first, cases, and, in, also"
32287,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.106060606,"the, to, which, with, of, for, and"
32288,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.106060606,"a, of, to, the, virus, that, analysis"
32289,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.106060606,"a, the, of, and, data, virus, that"
32290,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.106060606,"the, of, and, that, virus, a, to"
32291,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.106060606,"and, the, that, of, sars-cov-2, a, by"
32292,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.106060606,"by, was, that, the, is, to, of"
32293,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.106060606,"bats, the, was, to, which, of, and"
32294,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.106060606,"reservoir, a, as, high, and, certain, bat"
32295,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.106060606,"the, for, of, which, to, with, and"
32296,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.106060606,"to, of, the, which, bats, and, was"
32297,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.106060606,"another, of, the, thus, as, or, for"
32298,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.106060606,"recombination, of, with, to, and, the, for"
32299,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.106060606,"another, of, that, the, bat, homology, as"
32300,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.106060606,"et, that, of, with, and, the, sars-cov-2"
32301,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.106060606,"coronavirus, showed, and, identity, with, other, the"
32302,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.106060606,"to, the, and, bats, or, could, be"
32303,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.106060606,"to, that, the, of, and, as, more"
32304,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.106060606,"in, the, and, that, to, from, market"
32305,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.106060606,"sars-cov, and, the, of, that, sars-cov-2, a"
32306,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.106060606,"can, from, as, that, to, and, species"
32307,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.106060606,"to, a, high, and, which, species, as"
32308,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.106060606,"is, to, that, from, between, and, be"
32309,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.106060606,"of, that, the, a, ace2, receptor, as"
32310,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.106060606,"et, that, a, of, and, the, sars-cov-2"
32311,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.106060606,"the, of, a, to, in, at, was"
32312,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.106060606,"on, in, the, and, that, of, taken"
32313,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.106060606,"the, was, to, animals, we, a, by"
32314,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.106060606,"a, and, species, as, high, to, which"
32315,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.106060606,"and, the, for, zoonotic, of, sars-cov-2, in"
32316,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.106060606,"and, to, for, the, of, sars-cov-2, in"
32317,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.106060606,"sequences, analysis, that, of, in, intermediate, pangolin"
32318,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.106060606,"from, in, is, with, sars-cov-2, the, of"
32319,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.106060606,"a, of, in, province, that, with, virus"
32320,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.106060606,"et, al., (2020), from, in, the, to"
32321,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.106060606,"in, the, those, and, to, sars-cov-2, of"
32322,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.106060606,"can, as, that, natural, to, and, the"
32323,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.106060606,"sars-cov-2, the, rbd, and, that, of, is"
32324,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.106060606,"a, of, and, that, the, or, in"
32325,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.106060606,"as, a, of, the, in, with, sars-cov-2"
32326,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.106060606,"a, in, may, with, sars-cov-2, the, and"
32327,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.106060606,"or, of, and, the, in, may, favour"
32328,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.106060606,"in, with, other, and, to, sars-cov-2, the"
32329,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.106060606,"and, between, sars-cov-2, in, the, for, to"
32330,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.106060606,"for, the, of, dogs, that, from, in"
32331,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.106060606,"from, for, the, of, that, sars-cov-2, in"
32332,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.106060606,"a, result, of, the, and, china., in, to, it, with, evidence, that, from, suggested"
32333,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.106060606,"of, the, sars-cov-2, been, in, from, and"
32334,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.106060606,"that, a, the, of, sars-cov-2, pandemic, is"
32335,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.106060606,"a, sars-cov-2, therefore,, whether, to, in, the"
32336,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.106060606,"in, the, that, to, and, closely, related"
32337,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.106060606,"possible, a, bat, of, species,, and, are"
32338,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.106060606,"species,, a, of, and, the, species, different"
32339,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.106060606,"in, the, of, multiple, that, a, to"
32340,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.106060606,"and, sars-cov-2, to, other, the, in, with"
32341,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.106060606,"in, a, related, that, the, closely, to"
32342,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.106060606,"the, and, viruses, furin, cleavage, site, to"
32343,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.106060606,"sars-cov-2, may, in, a, and, the, with"
32344,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.106060606,"that, a, virus, in, province, of, with"
32345,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.106060606,"with, the, and, to, in, of, sequence"
32346,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.106060606,"this, with, a, and, of, the, in"
32347,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.106060606,"that, evidence, in, from, a, to, humans."
32348,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.106060606,"from, the, that, of, dogs, in, for"
32349,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.106060606,"evidence, to, result, from, a, of, in, the, and, china., it, suggested, that, with"
32350,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.106060606,"in, the, of, that, as, a, human"
32351,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.106060606,"the, to, that, closely, related, in, and"
32352,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.106060606,"a, virus, sequence, that, the, in, samples"
32353,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.106060606,"the, that, at, of, virus, and, to"
32354,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.106060606,"for, and, an, with, from, to, at, the, in, of, its, team, a, was"
32355,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.106060606,"from, the, team, was, for, to, a, with, and, in, of, at, its, an"
32356,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.106060606,"early, in, wuhan, the, of, and, reported"
32357,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.106060606,"in, are, and, this, that, the, sars"
32358,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.106060606,"in, the, that, are, at, and, with"
32359,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.106060606,"also, the, of, first, cases, and, in"
32360,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.106060606,"the, huanan, that, be, sars-cov-2, and, of"
32361,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.106060606,"sars-cov-2, the, for, in, zoonotic, and, of"
32362,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.106060606,"that, the, from, market, in, to, and"
32363,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.106060606,"the, in, and, on, that, taken, of"
32364,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.106060606,"that, the, in, and, to, through, of"
32365,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.106060606,"sars-cov-2, natural, on, the, with, to, virus"
32366,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.106060606,"in, the, a, that, virus, samples, sequence"
32367,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.106060606,"a, of, the, by, that, and, which"
32368,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.106060606,"of, the, we, this, that, sars-cov-2, in"
32369,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.106060606,"in, to, that, the, of, very, sars-cov-2"
32370,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.106060606,"and, the, of, rbd, that, sars-cov-2, is"
32371,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.106060606,"coronaviruses, in, that, of, sars-cov-2, based, and"
32372,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.106060606,"as, the, or, of, another, thus, for"
32373,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.106060606,"homology, bat, that, the, of, another, as"
32374,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.106060606,"that, the, of, receptor, ace2, as, a"
32375,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.106060606,"in, the, and, that, of, to, through"
32376,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.106060606,"have, been, and, in, to, the, of"
32377,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.106060606,"in, a, of, to, coronavirus, suggesting, that"
32378,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.106060606,"may, in, of, and, favour, the, or"
32379,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.106060606,"of, and, are, bat, species,, a, possible"
32380,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.106060606,"a, in, the, was, to, of, at"
32381,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.106060606,"sars-cov-2, from, of, in, the, and, been"
32382,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.106060606,"of, from, is, in, with, sars-cov-2, the"
32383,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.106060606,"from, at, in, the, virus, is, of"
32384,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.106060606,"of, and, different, species,, a, species, the"
32385,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.106060606,"and, sars-cov-2, to, pangolin, in, a, other"
32386,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.106060606,"the, and, other, showed, with, coronavirus, identity"
32387,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.106060606,"therefore,, whether, the, sars-cov-2, to, a, in"
32388,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.106060606,"therefore,, sars-cov-2, to, in, the, with, pangolin"
32389,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.106060606,"the, sars-cov, and, sars-cov-2, to, in, of"
32390,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.106060606,"a, of, the, sars-cov-2, that, sars-cov, and"
32391,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.106060606,"from, the, that, of, in, for, sars-cov-2"
32392,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.106060606,"of, sars-cov-2, was, to, the, its, in"
32393,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.106060606,"and, that, the, of, is, likely, natural"
32394,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.106060606,"to, the, have, been, in, of, and"
32395,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.106060606,"the, spike, which, a, is, in, bat"
32396,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.106060606,"sars-cov-2, and, in, coronaviruses, that, of, based"
32397,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.106060606,"in, of, sars-cov-2, recently, found, to, that"
32398,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.106060606,"is, between, and, from, be, to, that"
32399,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.106060606,"its, to, was, the, of, sars-cov-2, in"
32400,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.106060606,"in, the, a, coronavirus, demonstrating, that, coronaviruses"
32401,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.106060606,"also, a, coronavirus, the, and, that, to"
32402,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.106060606,"the, of, that, is, was, to, by"
32403,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.106060606,"et, al., (2020), in, to, the, from"
32404,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.106060606,"virus, from, in, is, at, the, of"
32405,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.106060606,"and, for, sars-cov-2, to, the, between, in"
32406,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.106060606,"of, and, which, related, to, in, covs"
32407,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.106060606,"in, be, that, relatively, are, hosts, sars-cov-2"
32408,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.106060606,"the, recombination, to, with, of, for, and"
32409,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.106060606,"with, that, the, of, sars-cov-2, et, and"
32410,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.106060606,"that, the, of, sars-cov-2, and, a, et"
32411,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.106060606,"and, to, the, bats, could, be, or"
32412,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.106060606,"and, sars-cov-2, are, bat, pangolin, in, viruses"
32413,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.106060606,"are, and, this, in, the, that, sars"
32414,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.106060606,"pangolin, with, sars-cov-2, therefore,, to, in, the"
32415,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.106060606,"are, to, bat, that, the, of, sars-cov-2"
32416,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.106060606,"in, of, to, sars-cov-2, and, the, those"
32417,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.106060606,"the, of, that, to, as, and, more"
32418,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.106060606,"of, early, reported, wuhan, and, the, in"
32419,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.106060606,"of, based, on, the, and, in, virus"
32420,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.106060606,"a, of, have, the, are, that, for"
32421,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.106060606,"the, of, at, that, virus, to, and"
32422,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.106060606,"and, it, this, the, of, that, in"
32423,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.106060606,"sars-cov-2, of, the, to, in, virus, rbd"
32424,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.106060606,"to, coronavirus, in, of, suggesting, that, a"
32425,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.106060606,"recently, found, in, to, that, of, sars-cov-2"
32426,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.106060606,"in, related, of, covs, and, which, to"
32427,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.106060606,"to, the, of, sars-cov-2, from, bats, hosts"
32428,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.106060606,"of, sars-cov-2, and, closely, related, from, bats"
32429,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.106060606,"the, in, of, very, to, that, sars-cov-2"
32430,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.106060606,"and, that, natural, of, the, is, likely"
32431,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.106060606,"that, be, hosts, sars-cov-2, are, in, relatively"
32432,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.106060606,"the, of, in, to, with, high, and"
32433,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.106060606,"viruses, to, and, furin, cleavage, site, the"
32434,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.106060606,"sars-cov-2, natural, virus, with, on, to, the"
32435,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.106060606,"on, in, the, of, virus, based, and"
32436,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.106060606,"in, the, rbd, of, to, sars-cov-2, virus"
32437,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.105882353,"the, not, to, have, would, that, has, in, of"
32438,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.105882353,"other, such, as, the, of, and, in, they, to"
32439,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.105882353,"the, cause, of, sars, in, is, closely, related, to"
32440,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.105882353,"how, a, virus, from, to, of, are, as, sold"
32441,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.105882353,"as, in, the, of, and, to, they, other, such"
32442,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.105882353,"holmes, et, al., the, to, in, this, of, and"
32443,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.105882353,"from, bats, in, the, china, market, a, and, are"
32444,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.105882353,"the, to, closely, related, sars, in, is, of, cause"
32445,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.105882353,"from, intermediate, to, the, of, that, sars-cov-2, in, a"
32446,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.105882353,"the, be, by, species, of, to, and, may, also"
32447,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.105882353,"only, a, of, and, the, to, from, species, humans,"
32448,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.105882353,"are, and, the, from, bats, a, market, in, china"
32449,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.105882353,"that, the, sars-cov-2, to, selection, in, this, of, natural"
32450,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.105882353,"the, of, and, that, a, in, human, sars, to"
32451,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.105882353,"of, has, to, would, have, that, not, in, the"
32452,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.105882353,"a, of, to, are, how, virus, from, sold, as"
32453,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.105882353,"the, of, to, species, may, be, also, and, by"
32454,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.105882353,"the, of, and, species, humans,, from, a, only, to"
32455,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.105882353,"from, reservoir, and, to, not, the, of, have, a"
32456,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.105882353,"that, of, from, to, intermediate, a, in, sars-cov-2, the"
32457,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.105882353,"not, a, of, have, and, the, to, from, reservoir"
32458,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.105882353,"a, by, from, was, in, that, the, to, of"
32459,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.105882353,"holmes, et, al., the, of, and, in, this, to"
32460,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.105882353,"to, sars-cov-2, in, the, this, that, of, natural, selection"
32461,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.105882353,"from, to, was, by, the, of, that, in, a"
32462,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.105882353,"sars-cov-2, of, the, and, with, to, sars-, cov-2, in"
32463,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.105882353,"sars-cov-2, be, of, natural, the, and, to, sars-, in"
32464,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.105882353,"in, with, the, and, to, sars-cov-2, of, sars-, cov-2"
32465,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.105882353,"and, in, to, be, the, of, sars-, natural, sars-cov-2"
32466,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.105769231,"in, a, of, for, were, found, to, infected, coronavirus, that, may"
32467,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.105769231,"in, may, of, found, that, for, to, were, infected, a, coronavirus"
32468,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.105691057,"we, of, the, have, to, live, wild, in, were, found, that, positive, for"
32469,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.105691057,"in, of, to, have, the, we, that, wild, were, live, for, found, positive"
32470,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.105691057,"to, the, as, viral, reservoirs, viruses., and, many, reservoir, species, high, have, humans"
32471,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.105691057,"another, of, evidence, that, the, a, from, animal, these, as, intermediate, for, infections"
32472,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.105691057,"as, the, reservoir, to, many, viruses., viral, species, have, high, and, reservoirs, humans"
32473,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.105691057,"as, a, of, the, animal, these, evidence, for, that, from, another, infections, intermediate"
32474,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.105263158,"horseshoe, bats, reservoir, of"
32475,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.105263158,"group, of, the, in, that, or"
32476,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.105263158,"and, from, in, sars-cov-2,, that, the, of, bats"
32477,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.105263158,"are, a, and, viruses"
32478,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.105263158,"in, a, coronaviruses, are, to, and"
32479,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.105263158,"and, which, a, in"
32480,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.105263158,"a, pangolin, to, sars-cov-2"
32481,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.105263158,"human, coronaviruses, are, bat"
32482,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.105263158,"sars-cov-2, to, human, in"
32483,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.105263158,"the, of, enzootic, into"
32484,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.105263158,"the, of, and, humans"
32485,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.105263158,"are, species, of, in"
32486,"Bats have been reported as being the rich source of 

coronaviruses","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.105263158,"have, the, of, coronaviruses"
32487,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.105263158,"of, that, virus, infected, were, and, more, than"
32488,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.105263158,"with, that, bats, more, for, than"
32489,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.105263158,"bat, to, genetic, similar"
32490,Bats are hosts of many coronaviruses,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.105263158,"many, coronaviruses"
32491,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.105263158,"sequences, to, bat, in"
32492,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.105263158,"sars-cov-2, than, in, and"
32493,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.105263158,"and, bats, to, in"
32494,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.105263158,"more, to, in, and"
32495,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.105263158,"of, more, to, than"
32496,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.105263158,"and, identified, genetic, sequences"
32497,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.105263158,"of, genetic, by, and"
32498,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.105263158,"sequences, of, and, from"
32499,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.105263158,"genetic, sequences, identified, and"
32500,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.105263158,"genetic, many, within, and"
32501,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.105263158,"the, are, to, and"
32502,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.105263158,"the, to, and, very"
32503,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.105263158,"genetic, to, the, and"
32504,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.105263158,"similar, sequences, and, sars-cov"
32505,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.105263158,"are, the, sars-cov, and"
32506,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.105263158,"and, very, to, the"
32507,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.105263158,"to, than, in, virus"
32508,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.105263158,"is, sars-cov-2, to, in"
32509,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.105263158,"a, and, for, is"
32510,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.105263158,"the, same, bats, are"
32511,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.105263158,"virus, the, to, bat, and, human"
32512,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.105263158,"with, the, of, may, have, to"
32513,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.105263158,"the, of, in, to, with, a"
32514,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.105263158,"in, it, is, the, sars-cov-2, infected"
32515,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.105263158,"in, with, the, to, sars-cov-2, is, of, as"
32516,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.105263158,"coronavirus, have, been, of, that, a"
32517,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.105263158,"t, that, a, sars-cov-2"
32518,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.105263158,"it, that, the, sars-cov-2, to, used"
32519,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.105263158,"the, of, a, genetically, in, to, that, and, or, virus, ace2, receptors, for, scientific"
32520,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.105263158,"human, have, in, which, other, and"
32521,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.105263158,"the, have, human, in, to, and"
32522,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.105263158,"is, the, of, to, sars-cov-2, coronaviruses"
32523,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.105263158,"to, of, which, have, a, sars-cov-2"
32524,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.105263158,"the, genetic, of, to, and, in"
32525,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.105263158,"a, the, from, by, that, sars-cov-2, in, before"
32526,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.105263158,"in, is, unlikely, that, the, sars-cov-2"
32527,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.105263158,"is, because, sars-cov-2, the, that, in"
32528,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.105263158,"in, the, is, sars-cov-2, that, virus"
32529,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.105263158,"within, and, many, genetic"
32530,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.105263158,"with, and, sars-cov-2, is"
32531,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.105263158,"is, with, a, and"
32532,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.105263158,"that, is, a, naturally"
32533,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.105263158,"that, is, a, shares, with, sars-cov-2"
32534,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.105263158,"coronaviruses, to, the, all, that, of"
32535,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.105263158,"to, that, the, of, and, are"
32536,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.105263158,"the, as, sars-cov-2, with"
32537,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.105263158,"as, the, to, that, sars-cov-2, natural"
32538,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.105263158,"that, host, sars-cov-2, to"
32539,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.105263158,"of, the, identity, bat"
32540,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.105263158,"the, bat, ratg13,, sequence"
32541,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.105263158,"has, natural, and, genome"
32542,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.105263158,"virus, been, and, genome"
32543,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.105263158,"and, are, a, viruses"
32544,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.105263158,"the, of, natural, a"
32545,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.105263158,"are, a, and, the"
32546,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.105263158,"the, of, are, a"
32547,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.105263158,"to, the, and, bat, virus, human"
32548,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.105263158,"to, the, covid-19, virus, and, was"
32549,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.105263158,"virus, that, to, human"
32550,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.105263158,"sars-cov-2, virus, that, bat"
32551,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.105263158,"that, virus, to, and, the, sars-cov-2"
32552,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.105263158,"sars-cov-2, and, or, of"
32553,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.105263158,"sars-cov-2, and, of, the, to, in, with, sars-cov, bat, covs"
32554,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.105263158,"to, sars-cov-2"
32555,"insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",Originating from reservoir of bat,0.105263158,"from, of"
32556,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",Originating from reservoir of bat,0.105263158,"of, reservoir"
32557,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.105263158,"a, the, bats, of, human, as"
32558,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.105263158,"of, the, has, human"
32559,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.105263158,"the, has, as, a, of, that"
32560,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.105263158,"the, of, viruses, been"
32561,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.105263158,"the, of, more, than, been, and"
32562,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.105263158,"host, of, and, the, bats, viruses"
32563,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.105263158,"that, a, the, of, and, is, to, an"
32564,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.105263158,"the, host, to, be, of, as"
32565,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.105263158,"a, virus, to, for, the, is"
32566,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.105263158,"that, and, be, for, to, the, in, with"
32567,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.105263158,"is, the, virus, to, be, in"
32568,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.105263158,"that, the, to, human"
32569,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.105263158,"the, was, to, a, virus, that, and, human, in, closest"
32570,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.105263158,"the, a, that, bats,, to, and"
32571,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.105263158,"the, bats, of, to"
32572,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.105263158,"the, of, sars-cov-2, intermediate"
32573,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.105263158,"the, wuhan, in, china, as, of"
32574,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.105263158,"in, the, of, has, been, and"
32575,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.105263158,"has, been, in, before"
32576,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.105263158,"the, of, that, wuhan, city,, to"
32577,"The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.105263158,"the, that, were, zoonotic"
32578,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.105263158,"of, the, in, to, that, animal"
32579,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.105263158,"a, to, in, and"
32580,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.105263158,"to, in, china, and"
32581,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.105263158,"is, an, of, and"
32582,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.105263158,"the, and, by, that"
32583,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.105263158,"the, has, been, shown"
32584,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.105263158,"that, species, of, the"
32585,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.105263158,"most, by, the, are"
32586,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.105263158,"that, the, of, bats, and, are"
32587,"Bats have been reported as being the rich source of 

coronaviruses","All human coronaviruses have animal origins, namely, natu- 

ral hosts",0.105263158,"have, coronaviruses"
32588,"zoonotic corona- 

viruses have become an increasing threat to human health,","All human coronaviruses have animal origins, namely, natu- 

ral hosts",0.105263158,"have, human"
32589,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.105263158,"the, bats, be, of"
32590,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.105263158,"the, of, and, reservoirs"
32591,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.105263158,"and, that, transmission, to, intermediate, species"
32592,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.105263158,"the, as, natural, for, from, and"
32593,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.105263158,"the, as, intermediate, for"
32594,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.105263158,"the, of, sars-cov-2, at"
32595,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.105263158,"the, genomic, sars-cov-2, at"
32596,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.105263158,"the, of, covid-19, through"
32597,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.105263158,"at, the, with, identity"
32598,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.105263158,"the, was, in, from"
32599,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",Bats are likely reservoir hosts for SARS-CoV-2,0.105263158,"bats, for"
32600,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.105263158,"is, a, sars-cov-2, the"
32601,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.105263158,"a, origin, the, is"
32602,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.105263158,"sars-cov-2, the, zoonotic, with, high, to"
32603,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.105263158,"outbreaks, to, the, other"
32604,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.105263158,"and, the, to, humans,"
32605,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.105263158,"the, to, was, in"
32606,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.105263158,"the, in, to, animals"
32607,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.105263158,"the, and, other, was"
32608,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.105263158,"and, in, the, to"
32609,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.105263158,"the, protein, of, sars-cov-2"
32610,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.105263158,"the, analysis, that, sars-cov-2"
32611,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.105263158,"the, in, that, of"
32612,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.105263158,"the, of, is, bat"
32613,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.105263158,"the, with, identity, genome"
32614,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.105263158,"bats, that, are, for"
32615,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","civet cats and raccoon dogs  

are the intermediate hosts",0.105263158,"are, the, and, hosts"
32616,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.105263158,"and, are, to, coronaviruses, in, a"
32617,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.105263158,"the, and, are, coronaviruses, that, to"
32618,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.105263158,"the, coronaviruses, from, and, in, with"
32619,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.105263158,"coronavirus, from, a, and, with, to, in, the"
32620,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.105263158,"the, that, are, to, a, with"
32621,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.105263158,"and, sars-cov-2, are, to"
32622,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.105263158,"of, sars-cov-2, and, to"
32623,"Bats have been reported as being the rich source of 

coronaviruses","with the first case being linked to  

a seafood market",0.105263158,"being, the"
32624,"According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses","with the first case being linked to  

a seafood market",0.105263158,"to, the"
32625,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","with the first case being linked to  

a seafood market",0.105263158,"linked, the, to, a"
32626,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","with the first case being linked to  

a seafood market",0.105263158,"a, market, with, the, being, to"
32627,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","with the first case being linked to  

a seafood market",0.105263158,"a, being, to, with"
32628,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.105263158,"in, to, humans, through"
32629,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.105263158,"evidence, bats, pangolins, sars-cov-2"
32630,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.105263158,"and, in, a, which"
32631,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.105263158,"that, and, the, by"
32632,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.105263158,"the, which, that, and"
32633,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.105263158,"the, that, a, and"
32634,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.105263158,"the, and, which, in"
32635,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.105263158,"the, zoonotic, a, in"
32636,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.105263158,"the, that, in, which"
32637,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.105263158,"that, the, origin, and"
32638,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.105263158,"originated, in, the, which"
32639,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.105263158,"the, that, a, in"
32640,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.105263158,"it, that, the, a"
32641,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.105263158,"has, been, with, that, and, sars-cov-2"
32642,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.105263158,"bat, to, as, genetic, similarity, sars-cov-2"
32643,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.105263158,"from, sars-cov-2, to, a, bat, and"
32644,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.105263158,"sars-cov-2, a, that, emerged"
32645,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.105263158,"a, origin, of, the"
32646,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.105263158,"the, to, that, a"
32647,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.105263158,"a, from, that, the, to, of"
32648,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.105263158,"genome, and, has, natural"
32649,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.105263158,"have, through, that, the"
32650,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.105263158,"that, are, the, natural, and, have"
32651,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.105263158,"coronavirus, from, the, have"
32652,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.105263158,"the, of, coronavirus, from, that, these"
32653,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.105263158,"of, the, at, that, suggest, have"
32654,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.105263158,"suggest, that, the, of, and, have"
32655,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.105263158,"enzootic, of, the, into"
32656,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.105263158,"the, was, that, sars-cov-2"
32657,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.105263158,"the, that, sars-cov-2, before"
32658,The COVID-19 most likely developed from bat origin coronaviruses,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.105263158,"likely, from"
32659,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.105263158,"from, to, the, of"
32660,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.105263158,"of, bat, coronaviruses,, sars-cov-2"
32661,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.105263158,"that, sars-cov-2, from, a, by, the, in, before"
32662,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.105263158,"that, sars-cov-2, a, progenitor, in, their"
32663,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.105263158,"in, the, of, that, sars-cov-2, and, this, a"
32664,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.105263158,"that, sars-cov-2, a, the, pandemic, of, at, from"
32665,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.105263158,"this, that, a, zoonotic, the, into, humans, early, of, in, at, least"
32666,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.105263158,"sars-cov-2, at, the, of"
32667,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.105263158,"sars-cov-2, host, zoonotic, humans"
32668,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.105263158,"the, most, for, sars-cov-2"
32669,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.105263158,"the, of, and, that, are, to"
32670,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.105263158,"that, transmission, of, to, sars-cov-2, the"
32671,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.105263158,"of, and, the, to, animals, through"
32672,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.105263158,"the, and, to, that, are, of"
32673,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.105263158,"the, cases, that, with, sars-cov-2, at"
32674,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.105263158,"a, the, that, two"
32675,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.105263158,"the, that, a, in, are, to"
32676,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.105263158,"study, that, to, a, in, the"
32677,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.105263158,"a, in, to, the"
32678,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.105263158,"the, study, that, in, a, to"
32679,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.105263158,"the, that, are, more"
32680,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.105263158,"that, are, the, a"
32681,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.105263158,"the, a, in, to, that, are"
32682,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.105263158,"with, and, is, a"
32683,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.105263158,"the, a, of, origin"
32684,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.105263158,"of, is, a, in, with, the"
32685,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.105263158,"market, the, virus, was"
32686,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.105263158,"he, of, the, a"
32687,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.105263158,"in, the, middle, and"
32688,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.105263158,"other, the, to, outbreaks"
32689,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.105263158,"the, outbreaks, in, were"
32690,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.105263158,"and, sars-cov-2, in, than"
32691,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.105263158,"sars-cov-2, at, the, genomic"
32692,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.105263158,"the, that, and, sars-cov-2"
32693,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.105263158,"the, huanan, market, in"
32694,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.105263158,"reservoir, sars-cov-2, that, the"
32695,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.105263158,"in, from, to, humans, at, and"
32696,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.105263158,"and, to, were, in"
32697,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.105263158,"from, to, humans, and"
32698,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.105263158,"and, the, zoonotic, spillover, of, in, a, published"
32699,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.105263158,"as, and, to, the, of, in, a, laboratory"
32700,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.105263158,"that, from, a, spillover"
32701,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.105263158,"a, sars-cov-2, with, that"
32702,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.105263158,"the, in, a, from, animals, market"
32703,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.105263158,"the, of, from, and, in, sars-cov-2"
32704,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.105263158,"live, animal, a, and, in, the"
32705,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.105263158,"the, of, sars-cov-2, a, in, animal"
32706,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.105263158,"the, of, from, two, in, sars-cov-2"
32707,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.105263158,"for, the, of, that, a, human, this, evidence, humans, out, as, to"
32708,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.105263158,"an, is, to, that, and, from"
32709,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.105263158,"are, known, and, in, that, to"
32710,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.105263158,"is, and, it, not, an, to"
32711,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.105263158,"and, the, of, to, viruses, are, as, they, other, in, for, virus"
32712,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.105263158,"a, that, sars-cov-2, in, progenitor, their"
32713,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.105263158,"in, that, had, or"
32714,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.105263158,"is, sars-cov-2, that, in"
32715,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.105263158,"in, is, sars-cov-2, that"
32716,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.105263158,"and, in, to, closely, related, that, the, of, coronavirus, is, are, sars-cov-2"
32717,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.105263158,"that, sars-cov-2, the, before"
32718,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.105263158,"the, with, cases, that, sars-cov-2, at"
32719,"Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.105263158,"the, infected, could, be"
32720,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.105263158,"in, the, market, from, a, animals"
32721,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.105263158,"in, animals, to, humans"
32722,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.105263158,"is, a, that, naturally"
32723,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.105263158,"in, a, that, to"
32724,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.105263158,"a, that, from, spillover"
32725,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.105263158,"covid-19, to, that, a"
32726,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.105263158,"a, to, that, originated"
32727,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.105263158,"in, originated, from, a"
32728,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.105263158,"a, the, of, is, and, that, to, an"
32729,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.105263158,"he, to, and, the, of, sars-cov-2"
32730,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.105263158,"that, the, outbreak, a, to, and"
32731,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.105263158,"that, the, of, sars-cov-2, and, likely"
32732,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.105263158,"the, of, an, very, to, that"
32733,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.105263158,"the, coronavirus, as, and"
32734,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.105263158,"the, that, coronavirus, to"
32735,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.105263158,"a, similarity, with, the"
32736,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.105263158,"that, the, with, to"
32737,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.105263158,"the, virus, that, and"
32738,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.105263158,"that, animals, and, from"
32739,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.105263158,"the, samples, from, that"
32740,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.105263158,"the, virus, from, and"
32741,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.105263158,"and, that, the, virus"
32742,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.105263158,"virus, that, the, samples"
32743,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.105263158,"the, that, virus, and"
32744,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.105263158,"of, that, and, to"
32745,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.105263158,"a, and, coronaviruses, species, to, that"
32746,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.105263158,"of, and, to, that"
32747,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.105263158,"to, have, of, and, that, a"
32748,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.105263158,"and, which, have, in, other, human"
32749,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.105263158,"that, from, and, animals"
32750,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.105263158,"the, horseshoe, of, and"
32751,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.105263158,"from, animals, to, and"
32752,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.105263158,"the, and, very, to"
32753,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.105263158,"a, and, to, the"
32754,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.105263158,"the, genome, that, covid-19"
32755,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.105263158,"a, genome, was, that, the, to"
32756,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.105263158,"that, the, and, bat"
32757,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.105263158,"the, and, a, to, that, bat"
32758,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.105263158,"as, the, of, be, to, host"
32759,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.105263158,"to, be, the, possible"
32760,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.105263158,"the, to, intermediate, of"
32761,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.105263158,"intermediate, host, was, the"
32762,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.105263158,"the, in, of, a"
32763,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.105263158,"of, the, in, with"
32764,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.105263158,"the, of, bats, in"
32765,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.105263158,"a, of, the, in, to, with"
32766,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.105263158,"in, a, with, and, to, the"
32767,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.105263158,"a, to, in, with, the, and"
32768,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.105263158,"and, a, of, in, the, to"
32769,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.105263158,"of, that, the, or, in, group"
32770,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.105263158,"virus, than, to, in"
32771,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.105263158,"that, had, or, in"
32772,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.105263158,"that, the, in, market, or, of"
32773,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.105263158,"the, coronavirus, that, from, to, and"
32774,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.105263158,"that, an, to, from, and, is"
32775,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.105263158,"from, the, that, a, sars-cov-2, to"
32776,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.105263158,"the, a, from, pangolin, that, intermediate"
32777,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.105263158,"pangolin, to, sars-cov-2, the, that, is"
32778,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.105263158,"and, be, transmitted, to"
32779,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.105263158,"that, of, from, the, which, for"
32780,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.105263158,"the, of, a, that, virus, from, to, and"
32781,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.105263158,"of, the, (manis, javanica), from, and"
32782,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.105263158,"covid-19, a, the, that, from, for"
32783,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","Bats have been reported as being the rich source of 

coronaviruses",0.105263158,"the, have, of, coronaviruses"
32784,"All human coronaviruses have animal origins, namely, natu- 

ral hosts","Bats have been reported as being the rich source of 

coronaviruses",0.105263158,"coronaviruses, have"
32785,"with the first case being linked to  

a seafood market","Bats have been reported as being the rich source of 

coronaviruses",0.105263158,"the, being"
32786,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","Bats have been reported as being the rich source of 

coronaviruses",0.105263158,"the, as"
32787,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.105263158,"sars-cov-2, to, pangolin, a"
32788,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.105263158,"has, been, shown, the"
32789,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.105263158,"have, from, the, coronavirus"
32790,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.105263158,"the, a, to, from"
32791,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.105263158,"the, of, sars-cov-2, and, he, to"
32792,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.105263158,"can, to, humans, and"
32793,"the close relation  

between SARS coronavirus and 2019-nCoV","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.105263158,"the, coronavirus"
32794,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.105263158,"the, sars-cov-2, isolated, from"
32795,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.105263158,"genetic, of, by, and"
32796,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.105263158,"the, and, genetic, to"
32797,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.105263158,"that, originated, a, to"
32798,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.105263158,"the, of, and, that, a, to"
32799,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.105263158,"the, of, that, a, and, to"
32800,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.105263158,"the, analysis, that, virus"
32801,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.105263158,"the, originated, and, a"
32802,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.105263158,"of, the, human, to"
32803,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.105263158,"the, one, of, and"
32804,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.105263158,"bat, to, is, the"
32805,Bats are hosts of many coronaviruses,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.105263158,"hosts, of"
32806,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.105263158,"between, intermediate, and, the"
32807,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.105263158,"one, of, to, bat"
32808,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.105263158,"is, shown, to, sars-cov-2"
32809,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.105263158,"and, in, to, bats"
32810,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.105263158,"the, humans,, to, and"
32811,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.105263158,"a, and, from, to, in, bats"
32812,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.105263158,"the, market, in, china"
32813,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.105263158,"in, and, the, virus"
32814,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.105263158,"a, are, the, and"
32815,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.105263158,"a, market, in, that, the, who, to, virus"
32816,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.105263158,"the, of, that, to"
32817,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.105263158,"of, the, origins, covid-19"
32818,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.105263158,"that, the, most, to"
32819,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.105263158,"virus, the, covid-19, was, to, and"
32820,Genetic evidence suggesting otherwise is yet to be presented.,"genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.105263158,"genetic, to"
32821,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.105263158,"that, was, at, a"
32822,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.105263158,"and, in, to, more"
32823,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.105263158,"to, the, in, and, that, animals"
32824,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.105263158,"that, the, likely, to"
32825,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.105263158,"the, to, in, is"
32826,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.105263158,"the, reservoirs, in, and"
32827,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.105263158,"to, is, similar, the"
32828,evidence suggests bats as its origin,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.105263158,"its, origin"
32829,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.105263158,"the, outbreak, of, and"
32830,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.105263158,"and, bat, cov, the"
32831,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.105263158,"to, the, of, bats"
32832,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.105263158,"to, that, the, of"
32833,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.105263158,"that, the, to, and"
32834,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.105263158,"the, is, a, of, and, it"
32835,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.105263158,"the, and, is, of, a, natural"
32836,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.105263158,"the, host"
32837,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.105263158,"the, could, be, infected"
32838,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.105263158,"were, in, outbreaks, the"
32839,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.105263158,"the, were, in, and"
32840,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.105263158,"the, possible, to, be"
32841,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.105263158,"to, therefore, could, be"
32842,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.105263158,"virus, the, market, was"
32843,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.105263158,"wuhan, the, in, of, as, china"
32844,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.105263158,"of, the, market, in, that, or"
32845,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.105263158,"however,, the, that, a, novel, coronavirus"
32846,"with the first case being linked to  

a seafood market","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.105263158,"the, to"
32847,"According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.105263158,"according, to"
32848,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.105263158,"close, of, sars-cov-2, to"
32849,"Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.105263158,"is, a, for, and"
32850,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.105263158,"sars-cov-2, the, that, used, to, it"
32851,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.105263158,"is, a, which, the, receptor, by"
32852,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.105263158,"bat, is, to, than"
32853,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.105263158,"to, the, of, bats, as, for"
32854,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.105263158,"of, could, be, to, the, transmission"
32855,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.105263158,"of, bats, to, and, the, infection"
32856,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.105263158,"at, the, of, which, rbd, with"
32857,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.105263158,"of, analysis, the, to, which, and"
32858,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","Scientific reports published so far include  

hosts, such as bats (28), pangolins (29), cats  

(11), and dogs (30)",0.105263158,"such, as, and, dogs"
32859,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.105263158,"in, to, humans, and"
32860,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.105263158,"genetic, and, that, sars-cov, of, bat"
32861,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.105263158,"genetic, viral, and, that, of, the"
32862,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.105263158,"that, sars-cov-2, cov, and, the, of"
32863,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.105263158,"human, are, bat, coronaviruses"
32864,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.105263158,"the, reservoir, it, of"
32865,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.105263158,"the, same, as, in"
32866,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.105263158,"are, the, as, a"
32867,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.105263158,"in, pangolin, the, of"
32868,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.105263158,"bat, that, of, and, genetic, sars-cov"
32869,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.105263158,"that, is, of, and"
32870,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.105263158,"has, the, virus, bats"
32871,"unnatural origin of SARS-CoV-2, but these people are 

simply wrong",Many of these CoVs can infect several animal species as well,0.105263158,"of, these"
32872,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.105263158,"virus, to, that, human"
32873,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.105263158,"a, for, the, is, virus, to"
32874,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.105263158,"to, humans, from, the"
32875,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.105263158,"the, virus, to, humans"
32876,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.105263158,"the, to, sars-cov-2, coronaviruses"
32877,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.105263158,"to, all, from, sars-cov-2"
32878,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.105263158,"the, to, bat, bats"
32879,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.105263158,"the, related, to, from"
32880,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.105263158,"sars-cov-2, from, bat, to"
32881,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.105263158,"to, from, the, of"
32882,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.105263158,"the, bats, to, of"
32883,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.105263158,"of, the, outbreak, in"
32884,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.105263158,"the, of, from, bats"
32885,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.105263158,"and, in, middle, the"
32886,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.105263158,"the, and, have, to, in, human"
32887,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.105263158,"and, to, the, could, human, or"
32888,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.105263158,"have, the, to, human"
32889,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.105263158,"the, been, from, to, infected, and"
32890,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.105263158,"from, an, animal, the"
32891,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.105263158,"a, that, and, sars-cov-2"
32892,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.105263158,"and, that, a, natural"
32893,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.105263158,"and, that, sars-cov-2, a"
32894,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.105263158,"the, species, sars-cov-2, and"
32895,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.105263158,"that, the, and, humans"
32896,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.105263158,"species, and, humans, the"
32897,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.105263158,"intermediate, that, transmission, to, and, species"
32898,"According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.105263158,"to, sars-cov-2, close, of"
32899,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.105263158,"by, and, to, of, sars-cov-2, is"
32900,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.105263158,"that, of, the, features"
32901,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.105263158,"the, coronavirus, to, of"
32902,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.105263158,"the, was, and, other"
32903,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.105263158,"the, virus, and, other"
32904,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.105263158,"coronavirus, the, with, other"
32905,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.105263158,"of, human, and, in, lung, with"
32906,"t some virus detected in pangolins 

were capable of infecting humans.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.105263158,"virus, detected, in, of"
32907,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.105263158,"of, and, different, between, in, the"
32908,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.105263158,"the, from, and, of, december, with"
32909,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",COVID-19 is a zoonotic virus,0.105263158,"a, virus"
32910,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.105263158,"of, the, covid-19, to"
32911,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.105263158,"of, covid-19, the, with"
32912,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.105263158,"of, the, virus, to"
32913,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.105263158,"be, of, the, with, to, virus"
32914,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.105263158,"the, as, coronavirus, and"
32915,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.105263158,"that, and, are, the"
32916,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.105263158,"and, that, the, to"
32917,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.105263158,"human, and, with, in, lung, of"
32918,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.105263158,"the, of, as, a, human, bats"
32919,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.105263158,"the, could, human, or, to, and"
32920,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.105263158,"the, of, sars-, to, bats, as"
32921,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.105263158,"or, bats, the, could, be, of, to, as, and, sars-cov"
32922,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.105263158,"genomic, that, sars-cov-2, the"
32923,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.105263158,"the, coronavirus, that, to"
32924,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.105263158,"that, the, to, of"
32925,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.105263158,"that, the, genomic, is"
32926,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.105263158,"to, highly, the, sars-cov-2"
32927,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.105263158,"to, sars-cov-2, of, the, that, coronaviruses"
32928,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.105263158,"the, sequence, of, to"
32929,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.105263158,"the, of, bat, identity"
32930,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.105263158,"the, sars-, and, bat"
32931,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.105263158,"identity, with, the, bat"
32932,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.105263158,"the, of, that, to, wuhan, city,"
32933,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.105263158,"the, to, was, from, of, bat"
32934,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.105263158,"that, and, sars-cov-2, other, on, the"
32935,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.105263158,"the, and, other, not"
32936,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.105263158,"human, sars-cov-2, to, in"
32937,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.105263158,"zoonotic, sars-cov-2, in, to"
32938,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.105263158,"animal, zoonotic, in, to"
32939,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.105263158,"the, genomic, that, is"
32940,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.105263158,"the, and, bat, sars-"
32941,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.105263158,"the, of, and, 103"
32942,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.105263158,"the, two, of, covid-19"
32943,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.105263158,"and, the, virus, of"
32944,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.105263158,"that, a, the, outbreak, and, to"
32945,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.105263158,"of, and, which, the"
32946,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.105263158,"at, that, was, a"
32947,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.105263158,"in, the, sars-cov-2, has, from, and"
32948,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.105263158,"sars-cov, from, and, the, of, sars-cov-2, in, a"
32949,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.105263158,"virus, bat, that, sars-cov-2"
32950,"this one jumped from bats origin  

into humans","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.105263158,"this, from"
32951,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.105263158,"sars-cov-2, in, from, is"
32952,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.105263158,"this, that, sars-cov-2, virus"
32953,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.105263158,"these, that, from, the, coronavirus, of"
32954,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.105263158,"a, that, from, the, pangolin, intermediate"
32955,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.105263158,"the, of, that, likely, a, pangolin"
32956,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.105263158,"the, of, that, a, in, for"
32957,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.105263158,"a, that, the, two"
32958,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.105263158,"the, genome, analysis, that"
32959,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.105263158,"in, that, the, and, of, bat"
32960,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.105263158,"and, of, the, humans"
32961,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.105263158,"the, to, are, most"
32962,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.105263158,"the, to, most, likely"
32963,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.105263158,"the, for, of, which, that, from"
32964,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.105263158,"revealed, the, for, from"
32965,"expended to make the simple point 

that COVID-19 had a natural origin.","Bats are natural hosts of many of the known  

coronaviruses",0.105263158,"the, natural"
32966,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Bats are natural hosts of many of the known  

coronaviruses",0.105263158,"are, the, bats, hosts"
32967,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.105263158,"coronaviruses, a, that, species, to, and"
32968,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.105263158,"and, from, bats, to, a, in"
32969,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.105263158,"a, from, coronavirus, which, sequence, sars-cov-2"
32970,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.105263158,"from, indicates, that, to, which, and"
32971,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.105263158,"and, can, species, to, bats, a, may, be"
32972,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.105263158,"a, bat, from, in, coronaviruses, sars-cov-2"
32973,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.105263158,"bats, and, a, which, to, that, in, as"
32974,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.105263158,"a, that, the, common, and, sars-cov-2"
32975,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.105263158,"studies, revealed, a, of, the, as"
32976,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.105263158,"the, pangolin, to, intermediate"
32977,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.105263158,"sars-cov-2, a, sequence, from, which, coronavirus"
32978,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.105263158,"sars-cov-2, has, the, a"
32979,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.105263158,"the, a, that, transmitted, to, and"
32980,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.105263158,"a, the, of, is, and, it"
32981,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.105263158,"the, transmitted, to, a"
32982,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.105263158,"the, that, of, is, it, hypothesis"
32983,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.105263158,"in, the, of, with, similar, at"
32984,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.105263158,"to, the, of, a"
32985,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.105263158,"to, genome, was, the"
32986,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.105263158,"to, a, in, the"
32987,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.105263158,"to, of, a, with"
32988,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.105263158,"that, a, to, in"
32989,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.105263158,"the, of, in, that, coronavirus, a"
32990,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.105263158,"closely, related, to, pangolin"
32991,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.105263158,"suggest, the, of, these"
32992,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.105263158,"the, infected, with, sars-cov-2"
32993,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.105263158,"the, with, sars-cov-2, are"
32994,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.105263158,"at, the, huanan, seafood, in, on"
32995,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.105263158,"the, to, be, of, could, transmission"
32996,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.105263158,"analysis, that, the, of"
32997,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.105263158,"a, of, sars-cov-2, the"
32998,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.105263158,"on, in, the, at, huanan, seafood"
32999,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.105263158,"the, of, from, was, to, bat"
33000,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.105263158,"the, of, bat, in, a, to"
33001,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.105263158,"sars-cov-2, closely, related, in"
33002,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.105263158,"the, of, that, an"
33003,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.105263158,"pangolin, sars-cov-2"
33004,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.105263158,"that, a, was, the, of, and"
33005,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.105263158,"that, and, for, on, the, in"
33006,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.105263158,"the, for, and, many"
33007,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.105263158,"the, been, of, viruses"
33008,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.105263158,"in, been, the, of"
33009,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.105263158,"of, the, in, been"
33010,"natural selection in humans  

following zoonotic transfer","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.105263158,"natural, in"
33011,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.105263158,"the, from, a, and"
33012,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.105263158,"sars-cov-2, and, pangolins, from"
33013,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.105263158,"pangolin, closely, related, to"
33014,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.105263158,"to, specific, of, which, in, the"
33015,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","this one jumped from bats origin  

into humans",0.105263158,"from, this"
33016,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","this one jumped from bats origin  

into humans",0.105263158,"this, origin"
33017,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","this one jumped from bats origin  

into humans",0.105263158,"this, bats"
33018,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.105263158,"the, a, to, animals"
33019,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.105263158,"the, to, a, transmitted"
33020,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.105263158,"the, to, a, than"
33021,"with the first case being linked to  

a seafood market","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.105263158,"the, linked, to, a"
33022,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.105263158,"the, of, as, a, covs, and"
33023,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.105263158,"of, and, viruses, a, species, the"
33024,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.105263158,"to, a, and, human, these, level"
33025,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.105263158,"the, of, and, species, a, human, as, to"
33026,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.105263158,"the, a, in, and"
33027,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.105263158,"has, the, of, and"
33028,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.105263158,"the, of, zoonotic, a"
33029,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.105263158,"this, that, bats, are"
33030,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.105263158,"wild, and, the, of"
33031,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.105263158,"the, of, and, in, viruses, to"
33032,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.105263158,"the, of, viruses, in, and, to"
33033,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.105263158,"from, as, natural, for, and, the"
33034,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.105263158,"the, of, covs, a, and, as"
33035,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.105263158,"to, sars-cov-2, has, similarity"
33036,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.105263158,"the, a, with, similarity"
33037,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.105263158,"the, possible, a, because"
33038,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.105263158,"a, in, the, for"
33039,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.105263158,"sars-cov-2, a, in, the, it, with"
33040,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.105263158,"the, similarity, it, for"
33041,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.105263158,"the, genetic, cov, in"
33042,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.105263158,"the, sars-cov-2, with, similarity"
33043,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.105263158,"with, the, sars-cov, and, sars-cov-2, to, bat, covs, in, of"
33044,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.105263158,"of, the, bat, human"
33045,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.105263158,"a, the, to, of"
33046,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.105263158,"a, possible, because, the"
33047,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.105263158,"yunnan, to, of, the"
33048,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.105263158,"virus, genome, and, been"
33049,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.105263158,"the, sars-cov-2, highly, to"
33050,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.105263158,"the, and, sars-cov-, 2"
33051,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.105263158,"had, been, the, available"
33052,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.105263158,"the, to, that, not"
33053,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.105263158,"the, been, of, and, more, than"
33054,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.105263158,"a, of, the, this, that, sars-cov-2, and, in"
33055,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.105263158,"and, in, to, that, the, of, is, sars-cov-2"
33056,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.105263158,"sars-cov-2, shares, with, is, a, that"
33057,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.105263158,"the, that, to, sars-cov-2, of, transmission"
33058,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.105263158,"from, the, that, of, in, sars-cov-2"
33059,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.105263158,"the, coron-, a, in, to, that, direct, of"
33060,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.105263158,"in, the, coronaviruses, from, and, with"
33061,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.105263158,"in, the, from, and, of, sars-cov-2"
33062,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.105263158,"from, in, two, the, of, sars-cov-2"
33063,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.105263158,"from, the, with, sars-cov-2"
33064,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.105263158,"that, of, has, a"
33065,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.105263158,"of, virus, that, bat"
33066,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.105263158,"is, to, the, that"
33067,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.105263158,"that, a, has, of"
33068,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.105263158,"is, that, a, host"
33069,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.105263158,"of, the, in, sars-cov-2"
33070,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.105263158,"sars-cov-2, of, the, high, to, in"
33071,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.105263158,"has, sars-cov-2, and, the, from, in"
33072,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.105263158,"and, in, to, the, sars-cov-2, has"
33073,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.105263158,"to, the, has, from, an, and"
33074,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.105263158,"bats, the, to, of, and, infection"
33075,"Those who eagerly peddle suggestions of 

laboratory involvement have consistently failed to present 

credible arguments to support their positions.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.105263158,"those, of, to, support"
33076,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.105263158,"of, the, reported, in"
33077,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.105263158,"the, sequence, bat, ratg13,"
33078,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.105263158,"sars-cov-, 2, and, the"
33079,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.105263158,"sequence, with, the, bat"
33080,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.105263158,"the, at, which, with, rbd, of"
33081,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.105263158,"of, with, sars-cov-2, ratg13"
33082,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.105263158,"of, that, with, than"
33083,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.105263158,"to, sars-cov-2,, and, at, the, is"
33084,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.105263158,"is, and, ratg13, to, the, in"
33085,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.105263158,"in, the, rbd, is, to, at"
33086,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.105263158,"a, in, the, to"
33087,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.105263158,"a, for, the, in"
33088,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.105263158,"the, to, human, ace2"
33089,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.105263158,"the, amino, acid, for"
33090,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.105263158,"in, to, the, protein"
33091,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.105263158,"sars-cov-2, with, as, the"
33092,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.105263158,"single, the, rbd, be, to, sars-cov-2"
33093,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.105263158,"for, the, and, be, in, with, that, to"
33094,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.105263158,"on, the, other, that, sars-cov-2, and"
33095,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.105263158,"that, the, in, to, humans, and"
33096,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.105263158,"that, to, sars-cov-2, in, and, pangolins"
33097,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.105263158,"that, sars-cov-2, the, with, and, to"
33098,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.105263158,"to, the, key, rbd, transmission, with"
33099,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.105263158,"that, the, in, and, to, through"
33100,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.105263158,"that, the, sars-cov-2, and, a, common"
33101,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.105263158,"study, the, sars-cov-2, and"
33102,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.105263158,"single, the, rbd, to, be, sars-cov-2"
33103,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.105263158,"of, the, is, species, possible, for"
33104,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.105263158,"to, humans, be, through, of, and"
33105,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.105263158,"an, intermediate, the, from"
33106,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.105263158,"the, of, that, was, to, and"
33107,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.105263158,"evidence, supporting, that, and"
33108,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.105263158,"species, and, in, the"
33109,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.105263158,"sars-cov-2, at, the, in"
33110,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.105263158,"of, the, market, at, in, samples, that, taken, from, dogs, intermediate, host"
33111,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.105263158,"the, host, of, intermediate"
33112,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.105263158,"sars-cov-2, to, in, found"
33113,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.105263158,"to, sars-cov-2, in, bat"
33114,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.105263158,"sars-cov-2, to, bat, coronavirus"
33115,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.105263158,"that, of, from, in, sars-cov-2, the"
33116,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.105263158,"from, market, in, that, the, of"
33117,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.105263158,"that, the, for, of"
33118,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.105263158,"evidence, that, rhinolophus, bats, the, of, and, in"
33119,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.105263158,"the, of, are, sars-cov-2."
33120,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.105263158,"reservoir, of, not, the"
33121,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.105263158,"natural, the, for, of"
33122,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.105263158,"are, for, including, the"
33123,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.105263158,"a, of, the, pandemic, from, that, sars-cov-2, at"
33124,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.105263158,"the, a, zoonotic, in"
33125,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.105263158,"a, of, the, or, to, virus"
33126,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.105263158,"the, of, natural, sars-cov-2, is, or"
33127,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.105263158,"are, in, of, species"
33128,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.105263158,"the, and, in, reservoirs"
33129,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.105263158,"the, of, are, and, in, one"
33130,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.105263158,"the, of, sars-cov-2, which"
33131,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.105263158,"sars-cov-2, including, of, coronaviruses"
33132,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.105263158,"and, the, of, animal"
33133,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.105263158,"of, reservoir, horseshoe, bats"
33134,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.105263158,"the, of, horseshoe, and"
33135,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.105263158,"sars-cov-2, the, species, and"
33136,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.105263158,"the, most, to, sars-cov-2"
33137,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.105263158,"to, and, in, china"
33138,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.105263158,"are, to, the, most"
33139,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.105263158,"the, that, most, to, bat, and"
33140,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.105263158,"the, viruses, and, to"
33141,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.105263158,"were, in, and, to"
33142,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.105263158,"the, virus, in, were"
33143,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.105263158,"the, virus, in, for"
33144,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.105263158,"to, the, of, bat"
33145,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.105263158,"bat, to, in, an"
33146,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.105263158,"of, the, in, different, between, and"
33147,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.105263158,"the, of, a, and, species, viruses"
33148,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.105263158,"the, of, that, to, in, covid-19"
33149,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.105263158,"the, to, in, of, a, bat"
33150,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.105263158,"as, in, the, of, and, are, to, viruses, for, they, other, virus"
33151,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.105263158,"sars-cov-2, which, have, to, a, of"
33152,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.105263158,"all, sars-cov-2, from, to"
33153,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.105263158,"a, with, to, of"
33154,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.105263158,"a, sars-cov-2, shared, with"
33155,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.105263158,"have, of, with, to"
33156,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.105263158,"bat, genetic, similar, to"
33157,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.105263158,"sars-cov-2, to, as, genetic, similarity, bat"
33158,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.105263158,"the, is, to, bat"
33159,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.105263158,"the, is, similar, to"
33160,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.105263158,"the, in, to, with, a, and"
33161,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.105263158,"in, the, to, sars-cov-2, at, which"
33162,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.105263158,"their, the, of, closely"
33163,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.105263158,"of, 103, the, and"
33164,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.105263158,"are, the, of, sars-cov-2."
33165,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.105263158,"is, to, the, that, by, researchers, wiv, additional"
33166,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.105263158,"the, of, that, human"
33167,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.105263158,"the, to, that, human"
33168,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.105263158,"that, have, through, the"
33169,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.105263158,"the, that, with, to"
33170,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.105263158,"the, have, human, to"
33171,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.105263158,"to, the, of, human"
33172,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.105263158,"to, the, human, ace2"
33173,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.105263158,"to, of, have, with"
33174,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.105263158,"the, of, than, to"
33175,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","This suggests that the BANAL series may be able to directly infect  

humans.",0.105263158,"the, to, this, that"
33176,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.105263158,"the, banal, of, is"
33177,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.105263158,"the, of, more, from"
33178,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.105263158,"have, a, of, the"
33179,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.105263158,"of, the, a, viruses"
33180,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.105263158,"of, the, viruses, furin, cleavage, site"
33181,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.105263158,"at, the, and, is, to, sars-cov-2,"
33182,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.105263158,"a, closely, related, to, the, and"
33183,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.105263158,"amino, acid, the, for"
33184,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.105263158,"human, to, a, level, and, these"
33185,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.105263158,"banal, is, the, of"
33186,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.105263158,"the, genetic, is, virus"
33187,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.105263158,"of, the, is, virus"
33188,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.105263158,"the, is, virus, be, in, to"
33189,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.105263158,"related, to, sars-cov-2, in"
33190,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.105263158,"in, closely, related, the"
33191,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.105263158,"sars-cov-2, the, virus, to"
33192,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.105263158,"the, origins, of, covid-19"
33193,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.105263158,"closely, related, to, and, a, the"
33194,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.105263158,"sars-cov-2, and, bat, to, the, in"
33195,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.105263158,"in, with, the, and, to, sars-cov-2, bat, are"
33196,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.105263158,"and, in, to, closely, related, the, are, sars-cov-2"
33197,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.105263158,"the, in, it, is, infected, sars-cov-2"
33198,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.105263158,"is, unlikely, that, sars-cov-2, the, in"
33199,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.105263158,"that, sars-cov-2, is, be"
33200,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.105263158,"the, case, of, a, between, and"
33201,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.105263158,"of, the, from, with, december, and"
33202,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.105263158,"a, and, with, the, of, from"
33203,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.105263158,"a, of, market, with, by, the, who, to"
33204,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.105263158,"a, of, the, this, that, early, at, least, zoonotic, in, into, humans"
33205,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.105263158,"a, virus, that, into, humans, contact, with, to, the, over"
33206,"with the first case being linked to  

a seafood market","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.105263158,"with, the, being, to, a, market"
33207,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.105263158,"that, the, virus, in, to, who, a, market"
33208,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.105263158,"the, by, a, who, market, to, of, with"
33209,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.105263158,"of, virus, that, is, similar, to, the, and, for, was"
33210,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.105263158,"that, to, human, this, as, the, out, humans, a, of, evidence, for"
33211,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.105263158,"the, of, human, to, a, and, species, as"
33212,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.105263158,"the, of, dogs, in, samples, taken, from, market, that, intermediate, host, at"
33213,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.105263158,"of, more, than, and, that, virus, were, infected"
33214,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.105263158,"the, virus, a, of, to, that, from, and"
33215,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.105263158,"was, from, that, identical, to, and"
33216,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.105263158,"that, a, of, virus, to, and, the, intermediate"
33217,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.105263158,"of, for, to, ace2, receptors, a, virus, or, scientific, that, in, and, genetically, the"
33218,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.105263158,"a, the, closest, to, that, in, human, virus, and, was"
33219,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.105263158,"are, viruses, on, the, in, and, evidence, that, bats, or"
33220,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.105263158,"to, the, 2, have, in, of, and, that, a, covid-19"
33221,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.105263158,"of, the, early, reported, cases, in"
33222,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.105263158,"in, the, of, which, to, specific"
33223,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.105263158,"a, the, natural, of, is, and"
33224,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.105263158,"evidence, to, the, of, and, origin"
33225,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.105263158,"in, the, live, animal, and, a"
33226,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.105263158,"are, that, to, and, known, in"
33227,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.105263158,"to, in, animal, zoonotic"
33228,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.105263158,"some, to, in, the, this, that"
33229,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.105263158,"a, the, at, are, that, to"
33230,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.105263158,"animal, in, the, are"
33231,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.105263158,"the, in, that, animal"
33232,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.105263158,"the, are, one, of, in, and"
33233,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.105263158,"the, published, in, a, zoonotic, spillover, of, and"
33234,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.105263158,"in, a, of, for, sars-cov-2, be, that, zoonotic"
33235,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.105263158,"that, a, the, virus, over, into, humans, with, contact, to"
33236,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Those who eagerly peddle suggestions of 

laboratory involvement have consistently failed to present 

credible arguments to support their positions.",0.105263158,"of, to, support, those"
33237,"Bats are natural hosts of many of the known  

coronaviruses","expended to make the simple point 

that COVID-19 had a natural origin.",0.105263158,"natural, the"
33238,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","expended to make the simple point 

that COVID-19 had a natural origin.",0.105263158,"a, to, the, that"
33239,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","expended to make the simple point 

that COVID-19 had a natural origin.",0.105263158,"the, that, a, covid-19"
33240,The COVID-19 most likely developed from bat origin coronaviruses,"expended to make the simple point 

that COVID-19 had a natural origin.",0.105263158,"the, covid-19"
33241,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.105263158,"sars-cov-2, from, pangolins, and"
33242,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.105263158,"that, and, sars-cov-2, to, pangolins, in"
33243,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.105263158,"and, that, in, sars-cov-2"
33244,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.105263158,"in, a, the, to"
33245,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.105263158,"the, to, and, a"
33246,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.105263158,"and, the, of, which"
33247,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.105263158,"the, and, a, in, to, of"
33248,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.105263158,"sars-cov-2, humans, zoonotic, host"
33249,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.105263158,"and, was, a, in"
33250,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.105263158,"samples, that, the, virus"
33251,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.105263158,"the, identity, with, bat"
33252,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.105263158,"the, bat, sequence, with"
33253,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.105263158,"the, bat, collected, in"
33254,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.105263158,"that, or, laboratory, is"
33255,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.105263158,"the, not, to, this, that, of"
33256,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.105263158,"a, the, that, sars-cov-2, human, or"
33257,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.105263158,"evidence, that, the, protein, of, to"
33258,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.105263158,"of, is, sars-cov-2, that"
33259,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.105263158,"related, that, of, coronavirus, is, sars-cov-2"
33260,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.105263158,"had, been, available, the"
33261,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.105263158,"the, virus, genetic, is"
33262,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","natural selection in humans  

following zoonotic transfer",0.105263158,"in, humans"
33263,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.105263158,"to, bat, bats, the"
33264,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.105263158,"sars-, to, the, bats, of, as"
33265,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.105263158,"for, it, similarity, the"
33266,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.105263158,"that, bats, the, reservoir, of, for"
33267,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.105263158,"the, all, of, coronaviruses, that, to"
33268,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.105263158,"to, sars-cov-2, is, that, the, pangolin"
33269,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.105263158,"this, in, some, the, that, to"
33270,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.105263158,"in, all, sars-cov-2, pangolin, this, that, the, is"
33271,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.105263158,"sars-cov-2, is, to, in, the, pangolin"
33272,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.105263158,"the, of, that, sars-cov-2, to, pangolin"
33273,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.105263158,"that, a, natural, and"
33274,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.105263158,"that, the, of, and, which, a"
33275,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.105263158,"that, the, features, of"
33276,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.105263158,"to, an, the, of, that, very"
33277,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.105263158,"the, of, sars-cov-2, an"
33278,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.105263158,"the, a, of, with, from, and"
33279,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.105263158,"of, the, a, from, these, or"
33280,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.105263158,"recombination, the, from, and"
33281,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.105263158,"the, identical, sars-cov-2, and"
33282,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","In the 

case of MERS, dromedaries were the principal host.",0.105263158,"were, of, in, the"
33283,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","In the 

case of MERS, dromedaries were the principal host.",0.105263158,"the, in"
33284,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.105263158,"the, that, not, to"
33285,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.105263158,"analysis, of, the, that"
33286,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.105263158,"the, closely, of, their"
33287,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.105263158,"the, coronavirus, of, that, a, covid-19"
33288,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.105263158,"the, their, bat, of"
33289,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.105263158,"that, the, new, of"
33290,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.105263158,"a, the, however,, novel, coronavirus, that"
33291,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.105263158,"the, of, and, that, a, in, viruses, to"
33292,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.105263158,"the, of, that, viruses, use, receptor"
33293,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.105263158,"the, and, to, of, genetic, in"
33294,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.105263158,"sars-cov, and, to, the, bats, of"
33295,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.105263158,"of, the, sequence, to"
33296,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.105263158,"genetic, the, cov, in"
33297,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.105263158,"and, from, to, which, indicates, that"
33298,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",The COVID-19 most likely developed from bat origin coronaviruses,0.105263158,"the, bat"
33299,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",The COVID-19 most likely developed from bat origin coronaviruses,0.105263158,"the, most"
33300,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.105263158,"the, of, species, is, possible, for"
33301,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.105263158,"the, of, from, a, these, or"
33302,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.105263158,"evidence, that, the, of, as, intermediate"
33303,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.105263158,"the, receptor-binding, domain, of"
33304,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.105263158,"the, intermediate, to, of"
33305,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.105263158,"virus, to, humans, the"
33306,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.105263158,"in, the, and, to, that, through"
33307,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.105263158,"and, are, to, in"
33308,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.105263158,"in, to, animals, humans"
33309,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.105263158,"to, be, and, transmitted"
33310,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.105263158,"can, be, in, animals"
33311,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.105263158,"to, that, originated, in"
33312,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",Bats are hosts of many coronaviruses,0.105263158,"of, bats"
33313,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",Bats are hosts of many coronaviruses,0.105263158,"of, hosts"
33314,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.105263158,"to, humans, through, in"
33315,"In the 

case of MERS, dromedaries were the principal host.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.105263158,"in, the"
33316,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.105263158,"in, of, reported, the"
33317,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.105263158,"of, cases, early, reported, the, in"
33318,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.105263158,"have, of, in, the"
33319,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.105263158,"that, of, the, most"
33320,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.105263158,"of, that, the, which"
33321,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.105263158,"that, bat, virus, of"
33322,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.105263158,"the, of, that, for, virus, was, similar, to, is, and"
33323,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.105263158,"that, a, of, have, been, coronavirus"
33324,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.105263158,"the, to, that, in, animals, and"
33325,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.105263158,"the, that, have, in, of, 2, to, and, a, covid-19"
33326,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.105263158,"that, the, of, a, coronavirus, covid-19"
33327,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.105263158,"that, have, natural, and, are, the"
33328,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.105263158,"evidence, of, in, rhinolophus, bats, the, and, that"
33329,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.105263158,"the, of, that, bats, reservoir, for"
33330,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.105263158,"the, which, that, in"
33331,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.105263158,"the, virus, were, in"
33332,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.105263158,"in, animals, can, be"
33333,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.105263158,"of, the, huanan, market"
33334,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.105263158,"of, the, two, covid-19"
33335,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.105263158,"in, province,, the, with"
33336,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.105263158,"the, has, of, to, with, that"
33337,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.105263158,"the, of, to, that, this, not"
33338,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.105263158,"this, that, have, in"
33339,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.105263158,"studies, revealed, the, of, as, a"
33340,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.105263158,"of, the, have, in"
33341,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.105263158,"that, the, of, species"
33342,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.105263158,"the, in, bat, collected"
33343,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.105263158,"bats, the, of, and, host, viruses"
33344,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.105263158,"and, bat, the, between, viruses, in"
33345,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.105263158,"of, to, be, through, humans, and"
33346,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.105263158,"is, the, to, from"
33347,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.105263158,"humans, from, and, to"
33348,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.105263158,"the, to, from, humans"
33349,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.105263158,"from, and, to, be, the, scenario"
33350,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.105263158,"the, intermediate, host, was"
33351,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.105263158,"the, species, and, humans"
33352,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.105263158,"the, closely, related, in"
33353,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.105263158,"and, a, to, bat, are, not, of, but"
33354,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.105263158,"sars-cov, and, to, the, bats, could, be, of, or, as"
33355,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.105263158,"a, and, species, can, be, to, may, bats"
33356,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.105263158,"and, the, was, of"
33357,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.105263158,"the, in, a, market"
33358,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.105263158,"a, and, was, the"
33359,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.105263158,"a, of, the, between, and, case"
33360,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.105263158,"a, and, in, the"
33361,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.105263158,"the, of, from, (manis, javanica), and"
33362,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.105263158,"the, isolated, from, sars-cov-2"
33363,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.105263158,"sars-cov-2, from, is, in"
33364,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.105263158,"in, pangolins, of, their"
33365,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.105263158,"sars-cov-2, from, viruses, and"
33366,"t some virus detected in pangolins 

were capable of infecting humans.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.105263158,"virus, in, pangolins, of"
33367,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","t some virus detected in pangolins 

were capable of infecting humans.",0.105263158,"virus, pangolins, in, of"
33368,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.105263158,"of, in, pangolins, their"
33369,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.105263158,"the, intermediate, between, and"
33370,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.105263158,"the, from, an, intermediate"
33371,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.",0.105263158,"that, of, evidence, provide"
33372,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.105263158,"the, outbreak, and, of"
33373,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.105263158,"and, that, is, of"
33374,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.105263158,"from, to, related, the"
33375,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.105263158,"to, the, most, likely"
33376,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.105263158,"the, a, most, likely, from, to"
33377,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.105263158,"from, the, for, likely"
33378,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.105263158,"through, the, animals, to, and, of"
33379,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.105263158,"the, of, that, has, as, a"
33380,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.105263158,"a, the, to, that, bats,, and"
33381,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.105263158,"the, been, from, infected, to, and"
33382,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.105263158,"the, to, a, from, most, likely"
33383,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.105263158,"the, that, has, of, and, to"
33384,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.105263158,"that, sars-cov-2, with, has, been, and"
33385,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.105263158,"identity, sars-cov-2, with, and"
33386,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.105263158,"in, the, a, coronavirus, from, to, and, with"
33387,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.105263158,"from, to, and, be, the, scenario"
33388,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.105263158,"showed, sars-cov-2, has, to, and, with"
33389,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.105263158,"the, identity, sars-cov-2, with, and, 98.6%,"
33390,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.105263158,"on, the, in, is"
33391,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.105263158,"the, bats, in, is"
33392,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.105263158,"the, bats, in, and"
33393,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.105263158,"bats, and, the, in"
33394,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.105263158,"is, of, an, and"
33395,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.105263158,"a, the, of, is, virus, that"
33396,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.105263158,"the, of, virus, is"
33397,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.105263158,"the, of, a, virus"
33398,"All human coronaviruses have animal origins, namely, natu- 

ral hosts","zoonotic corona- 

viruses have become an increasing threat to human health,",0.105263158,"human, have"
33399,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.105263158,"for, the, of, virus, and, to"
33400,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.105263158,"the, of, virus, to"
33401,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.105263158,"a, on, origin, of"
33402,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.105263158,"suggest, that, have, the, at, of"
33403,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.105263158,"the, virus, has, to, that, of"
33404,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.105263158,"the, of, or, to, a, virus"
33405,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.105263158,"at, are, a, the, that, to"
33406,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.105263158,"the, of, that, are, to, a"
33407,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","ARS-CoV-2 is a 

natural virus, not a lab-created one.",0.105263158,"a, is"
33408,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","ARS-CoV-2 is a 

natural virus, not a lab-created one.",0.105263158,"is, natural, a, not"
33409,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.105263158,"are, the, most, by"
33410,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.105263158,"the, other, with, coronavirus"
33411,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.105263158,"animal, are, in, the"
33412,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.105263158,"sars-cov-2, from, to, bat"
33413,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.105263158,"bat, to, an, in"
33414,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.105263158,"in, to, that, sars-cov-2"
33415,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.105263158,"that, sars-cov-2, to, host"
33416,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.105263158,"that, host, is, a"
33417,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.105263158,"that, is, laboratory, or"
33418,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.105263158,"he, of, a, the"
33419,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.105263158,"the, sars-cov-2, reservoir, that"
33420,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.105263158,"a, the, has, sars-cov-2"
33421,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.105263158,"the, reservoir, of, not"
33422,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.105263158,"the, of, has, a"
33423,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.105263158,"the, other, and, not"
33424,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.105263158,"the, many, and, for"
33425,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.105263158,"the, in, a, as, to, of, and, laboratory"
33426,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.105263158,"a, sars-cov-2, and, sars-cov, the, of, from, in"
33427,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.105263158,"to, the, that, been, by, from, and, this"
33428,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.105263158,"in, a, of, for, sars-cov-2, to, that, may"
33429,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.105263158,"the, from, an, animal"
33430,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.105263158,"the, likely, as, for"
33431,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.105263158,"the, for, from, likely"
33432,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.105263158,"in, humans, that, sars-cov-2"
33433,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.105263158,"was, the, sars-cov-2, to"
33434,Genetic evidence suggesting otherwise is yet to be presented.,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.105263158,"to, be"
33435,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.105263158,"the, a, is, origin"
33436,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.105263158,"that, the, of, viral, and, genetic"
33437,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.105263158,"the, genetic, of, natural"
33438,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.105263158,"suggest, that, the, origin"
33439,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.105263158,"the, hypothesis, is, that, of, it"
33440,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.105263158,"the, is, of, natural, sars-cov-2, or"
33441,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.105263158,"that, natural, the, scenario, of, is"
33442,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.105263158,"the, of, that, sars-cov-2, are, with"
33443,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.105263158,"the, of, that, sars-cov-2, is, for"
33444,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.105263158,"of, has, the, a"
33445,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.105263158,"the, and, origin, of"
33446,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.105263158,"is, and, of, sars-cov-2, to, by"
33447,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.105263158,"in, to, the, sars-cov-2, has, and"
33448,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.105263158,"a, the, receptor, which, is, by"
33449,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.105263158,"was, that, from, identical, to, and"
33450,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.105263158,"viruses, sars-cov-2, from, and"
33451,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.105263158,"ratg13, sars-cov-2, that, are"
33452,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.105263158,"bat, coronaviruses,, of, sars-cov-2"
33453,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.105263158,"ratg13, of, with, sars-cov-2"
33454,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.105263158,"ratg13, bat, of, than"
33455,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.105263158,"the, is, by, wiv, researchers, to, additional, that"
33456,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.105263158,"from, and, to, this, by, the, that, been"
33457,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.105263158,"genetic, natural, of, the"
33458,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.105263158,"sequences, from, of, and"
33459,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.105263158,"and, sequences, similar, sars-cov"
33460,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.105263158,"the, origin, and, that"
33461,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.105263158,"the, that, scenario, of, natural, is"
33462,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.105263158,"that, might, the, for"
33463,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.105263158,"sars-cov-2, from, to, a, and, bat"
33464,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.105263158,"sars-cov-2, bats, pangolins, evidence"
33465,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.105263158,"that, evidence, supporting, and"
33466,evidence suggests bats as its origin,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.105263158,"evidence, bats"
33467,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.105263158,"the, covid-19, genome, that"
33468,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.105263158,"analysis, that, the, virus"
33469,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.105263158,"analysis, the, genome, that"
33470,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.105263158,"the, genome, to, that, was, a"
33471,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.105263158,"from, the, market, that, of, in"
33472,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.105263158,"a, that, the, it"
33473,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.105263158,"the, to, that, most"
33474,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.105263158,"the, likely, to, that"
33475,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.105263158,"the, are, as, a"
33476,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.105263158,"analysis, the, to, which, of, and"
33477,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.105263158,"of, the, that, which"
33478,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.105263158,"suggest, that, the, bat"
33479,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.105263158,"sars-cov-2, in, at, the"
33480,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.105263158,"in, bat, sequences, to"
33481,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.105263158,"to, one, of, bat"
33482,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.105263158,"sars-cov-2, is, a, to, the, for"
33483,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.105263158,"in, the, and, to, sars-cov-2, is, of, ratg13"
33484,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.105263158,"the, of, intermediate, a, that, virus, to, and"
33485,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.105263158,"the, have, been, as"
33486,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.105263158,"we, sars-cov-2, to, the"
33487,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.105263158,"with, that, the, of, sars-cov-2, and"
33488,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.105263158,"sars-cov-2, to"
33489,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.105263158,"shown, sars-cov-2, is, to"
33490,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.105263158,"is, than, to, bat"
33491,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.105263158,"to, is, ratg13, bat"
33492,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.105263158,"evidence, that, bats, in, the, or, and, are, on, viruses"
33493,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.105263158,"more, than, that, bats, for, with"
33494,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.105263158,"with, sars-cov-2, are, the"
33495,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.105263158,"sars-cov-2, that, are, ratg13"
33496,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.105263158,"that, likely, the, of, sars-cov-2, and"
33497,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.105263158,"more, from, the, of"
33498,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.105263158,"is, that, sars-cov-2, because, the, in"
33499,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.105263158,"the, and, in, is, to, ratg13"
33500,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.105263158,"to, in, sars-cov-2, the, bat, and"
33501,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.105263158,"and, the, in, viruses, between, bat"
33502,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same",0.105263158,"the, bat, and, sars"
33503,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.105263158,"pangolin, sars-cov-2, in, the, all, this, that, is"
33504,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.105263158,"the, sars-cov-2, is, same, with, and"
33505,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.105263158,"the, which, originated, in"
33506,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.105263158,"pangolin, to, sars-cov-2, in, the, is"
33507,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.105263158,"the, is, sars-cov-2, or"
33508,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.105263158,"as, of, the, in, is, to, with, sars-cov-2"
33509,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.105263158,"are, to, in, with, sars-cov-2, the, bat, and"
33510,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.105263158,"and, of, sars-cov-2, ratg13, in, is, the, to"
33511,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.105263158,"bat, that, the, sars-cov-2"
33512,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.105263158,"suggest, that, origin, the"
33513,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.105263158,"the, that, sars-cov-2, with"
33514,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.105263158,"bats, that, are, this"
33515,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.105263158,"of, sars-cov-2, and, or"
33516,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.105263158,"their, the, of, bat"
33517,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.105263158,"the, of, origin, and"
33518,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.105263158,"have, this, that, in"
33519,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.105263158,"this, sars-cov-2, that, bats"
33520,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.105263158,"the, and, of, evidence, origin, to"
33521,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.105263158,"the, of, evidence, that, sars-cov-2, for"
33522,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.105263158,"the, patients, wuhan, in, china, of"
33523,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.105263158,"of, and, the, in, between, bat"
33524,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.105263158,"cov, that, the, of, sars-cov-2, and"
33525,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.105263158,"a, origin, of, on"
33526,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.105263158,"are, the, of, a"
33527,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.105263158,"the, a, that, are, to, with"
33528,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.105263158,"the, of, a, pangolin, that, likely"
33529,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.105263158,"the, to, than, a"
33530,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.105263158,"a, of, the, are, that, to"
33531,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.105263158,"the, that, are, with, of, sars-cov-2"
33532,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.105263158,"has, to, that, and"
33533,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.105263158,"to, sars-cov-2, that, and"
33534,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.105263158,"that, to, and, has"
33535,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.105263158,"showed, and, with, sars-cov-2, has, to"
33536,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.105263158,"and, bat-sl-cov-2, pangolin-cov, with"
33537,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.105263158,"the, of, is, and, with, to"
33538,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.105263158,"identity, with, and, sars-cov-2"
33539,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.105263158,"98.6%,, and, identity, with, sars-cov-2, the"
33540,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.105263158,"and, sars-cov-2, with, the, same, is"
33541,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.105263158,"and, of, pangolin-cov, with"
33542,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.105263158,"revealed, from, the, for"
33543,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.105263158,"the, from, and, recombination"
33544,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.105263158,"that, the, in, and"
33545,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.105263158,"that, sars-cov-2, in, and"
33546,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.105263158,"recombination, the, of, pangolin-cov"
33547,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.105263158,"a, and, the, in"
33548,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.105263158,"originated, in, from, a"
33549,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.105263158,"a, originated, the, and"
33550,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.105263158,"a, in, and, the"
33551,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.105263158,"the, and, are, sars-cov"
33552,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.105263158,"a, that, the, are"
33553,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.105263158,"the, for, and, of"
33554,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.105263158,"the, and, a, that, are, of"
33555,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.105263158,"and, with, the, sars-cov-2"
33556,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.105263158,"the, pangolin-cov, recombinant, with"
33557,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.105263158,"the, identical, and, sars-cov-2"
33558,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.105263158,"and, the, virus, in"
33559,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.105263158,"of, the, in, pangolin"
33560,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.105263158,"that, the, of, new"
33561,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.105263158,"sars-cov-2, similarity, with, the"
33562,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.105263158,"the, has, of, that, to, and"
33563,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.105263158,"the, bat, and, that"
33564,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.105263158,"the, of, and, bat, that, in"
33565,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.105263158,"the, and, in, that, bat, of"
33566,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.105263158,"is, that, sars-cov-2, the, virus, in"
33567,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.105263158,"at, the, in, rbd, is, to"
33568,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.105263158,"in, which, to, sars-cov-2, at, the"
33569,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.105263158,"as, intermediate, for, the"
33570,"Bats have been reported as being the rich source of 

coronaviruses","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.105263158,"as, the"
33571,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.105263158,"sars-cov-2, pangolin"
33572,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.105263158,"the, virus, has, of, to, that"
33573,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.105263158,"the, virus, has, bats"
33574,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.105263158,"sars-cov-2, virus, that, this"
33575,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.105263158,"bat-sl-cov-2, and, pangolin-cov, with"
33576,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.105263158,"of, with, pangolin-cov, and"
33577,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.105263158,"the, of, a, zoonotic"
33578,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.105263158,"transmission, to, the, key, rbd, with"
33579,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.105263158,"recombination, pangolin-cov, the, of"
33580,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.105263158,"the, with, pangolin-cov, recombinant"
33581,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.105263158,"that, the, bat, was"
33582,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.105263158,"the, that, in, as"
33583,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.105263158,"that, was, the, as"
33584,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.105263158,"animal, in, the, that"
33585,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.105263158,"is, that, be, sars-cov-2"
33586,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.105263158,"sars-cov-2, is, that, to"
33587,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.105263158,"is, to, sars-cov-2, that"
33588,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.105263158,"study, the, and, sars-cov-2"
33589,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.105263158,"the, of, an, sars-cov-2"
33590,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.105263158,"the, sars-cov-2, and, bat"
33591,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.105263158,"the, bat, be, of"
33592,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.105263158,"the, animal, of, sars-cov-2"
33593,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.105263158,"in, the, animal, a, of, sars-cov-2"
33594,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.105263158,"in, the, of, that, a, sars-cov-2"
33595,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.105263158,"in, the, of, a, that, for"
33596,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.105263158,"the, virus, for, in"
33597,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.105263158,"the, that, of, sars-cov-2, is, for"
33598,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.105263158,"evidence, that, the, of, for, sars-cov-2"
33599,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.105263158,"the, for, covid-19, a, that, from"
33600,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.105263158,"the, sars-cov-2, human, a, or, that"
33601,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.105263158,"not, it, an, to, and, is"
33602,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.105263158,"it, the, of, reservoir"
33603,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.105263158,"sars-cov-2, a, coronaviruses, from, bat, in"
33604,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.105263158,"the, zoonotic, origin, a"
33605,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.105263158,"are, the, for, including"
33606,"with the first case being linked to  

a seafood market","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.105263158,"with, being, to, a"
33607,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.105263158,"be, that, for, zoonotic, of, sars-cov-2, in, a"
33608,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.105263158,"to, for, of, that, sars-cov-2, may, in, a"
33609,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.105263158,"a, and, as, to, which, that, in, bats"
33610,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.105263158,"at, the, identity, with"
33611,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.105263158,"the, genome, identity, with"
33612,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.105263158,"the, with, in, province,"
33613,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.105263158,"the, was, that, to"
33614,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.105263158,"to, the, of, yunnan"
33615,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.105263158,"to, was, the, sars-cov-2"
33616,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.105263158,"to, in, the, protein"
33617,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.105263158,"to, sars-cov-2, of, in, the, that"
33618,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.105263158,"that, sars-cov-2, to, in"
33619,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.105263158,"the, of, that, to, animal, in"
33620,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.105263158,"of, and, that, the, sars-cov-2,, from, in, bats"
33621,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.105263158,"the, that, to, are, closely, related, coronavirus, in, is, of, and, sars-cov-2"
33622,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.105263158,"in, the, of, is, to, that, sars-cov-2, and"
33623,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.105263158,"are, closely, related, to, in, sars-cov-2, the, and"
33624,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.105263158,"is, that, sars-cov-2, of, related, coronavirus"
33625,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.105263158,"of, bat, than, ratg13"
33626,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.105263158,"that, direct, of, to, a, in, coron-, the"
33627,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.105263158,"but, a, bat, to, not, of, and, are"
33628,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.105263158,"that, are, the, a, of, and"
33629,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.105263158,"bat, ratg13, is, to"
33630,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.105263158,"to, have, with, the, of, may"
33631,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.105263158,"the, of, to, with, that, pangolin"
33632,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.105263158,"the, of, protein, to, that, evidence"
33633,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.105263158,"of, evidence, that, the, as, intermediate"
33634,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.105263158,"to, of, more, than"
33635,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.105263158,"to, the, high, with, sars-cov-2, zoonotic"
33636,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.105263158,"with, to, be, the, of, virus"
33637,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.105263158,"the, high, of, to, sars-cov-2, in"
33638,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.105263158,"the, of, receptor-binding, domain"
33639,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.105263158,"the, and, to, bat, coronaviruses, of"
33640,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.105263158,"the, is, that, a"
33641,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.105263158,"sars-cov-2, is, the, or"
33642,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.10483871,"to, the, were, as, for, a, in, of, from, analysis, that, have, found"
33643,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.10483871,"as, a, of, the, market, live, were, in, it, with, infected, that, suggested"
33644,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.10483871,"it, suggested, that, the, infected, with, in, market, live, were, as, a, of"
33645,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.10483871,"in, a, of, to, have, the, that, analysis, from, were, for, found, as"
33646,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.10483871,"the, of, a, meat,, to, live, animal, in, and, market, were, at, palm"
33647,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.10483871,"the, and, of, a, to, were, in, live, animal, palm, at, market, meat,"
33648,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.104761905,"in, a, of, to, the, for, this, and, more, than, virus"
33649,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.104761905,"the, only, that, in, for, of, were, to, and, with, a"
33650,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.104761905,"in, the, of, virus, for, more, than, to, and, this, a"
33651,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.104761905,"that, by, a, of, virus, with, similar, to, and, the, for"
33652,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.104761905,"viruses, to, the, in, bats, of, and, that, animals, a, emergence"
33653,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.104761905,"for, the, of, and, were, that, a, only, in, with, to"
33654,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.104761905,"the, animals, to, in, a, of, viruses, emergence, that, bats, and"
33655,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.104761905,"the, for, to, a, virus, that, similar, with, and, by, of"
33656,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.104651163,"have, the, sars-cov-2, and, of, new, virus, to, that"
33657,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.104651163,"the, that, binds, ace2, a, novel, virus, in, covid-19"
33658,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.104651163,"a, of, the, that, and, are, in, their, into"
33659,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.104651163,"that, to, as, the, humans, a, of, evidence, natural"
33660,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.104651163,"are, a, the, of, and, in, that, their, into"
33661,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.104651163,"market,, the, huanan, was, and, of, cases, were, to"
33662,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.104651163,"evidence, to, the, that, as, a, of, humans, natural"
33663,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.104651163,"that, the, of, was, to, “the, evidence, we, a"
33664,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.104651163,"that, a, was, the, of, “the, evidence, we, to"
33665,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.104651163,"the, huanan, with, december, market, january, of, cases, by"
33666,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.104651163,"and, the, to, as, a, bats, that, virus, is"
33667,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.104651163,"the, is, that, have, of, to, by, and, an"
33668,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.104651163,"outbreak, market,, the, huanan, seafood, was, december, and, of"
33669,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.104651163,"of, the, cases, were, to, huanan, market,, and, was"
33670,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.104651163,"of, cases, december, the, huanan, market, with, by, january"
33671,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.104651163,"huanan, seafood, market,, the, outbreak, was, december, and, of"
33672,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.104651163,"1,, of, cases, to, the, huanan, seafood, market,, had"
33673,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.104651163,"sars-cov-2, of, to, virus, have, that, and, new, the"
33674,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.104651163,"and, the, of, to, a, infect, that, virus, is"
33675,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.104651163,"market,, the, huanan, seafood, 1,, of, cases, to, had"
33676,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.104651163,"in, a, of, horseshoe, with, that, virus, yunnan, province"
33677,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.104651163,"that, are, the, to, suggesting, these, may, in, and"
33678,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.104651163,"to, is, a, virus, that, bats, and, the, as"
33679,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.104651163,"the, is, that, virus, to, infect, a, of, and"
33680,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.104651163,"are, a, and, this, in, the, events, that, to"
33681,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.104651163,"the, that, virus, can, in, with, which, they, different"
33682,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.104651163,"the, of, that, are, to, a, cluster, with, bat"
33683,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.104651163,"the, and, that, of, collected, were, huanan, half, between"
33684,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.104651163,"of, and, a, to, that, in, humans,, as, human"
33685,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.104651163,"the, by, bat, all, from, species, collected, in, china"
33686,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.104651163,"that, a, horseshoe, virus, in, yunnan, province, of, with"
33687,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.104651163,"the, of, and, have, that, is, an, to, by"
33688,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.104651163,"and, the, to, are, a, that, this, in, events"
33689,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.104651163,"collected, of, the, that, were, between, and, half, huanan"
33690,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.104651163,"covid-19, binds, ace2, a, novel, virus, that, in, the"
33691,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.104651163,"the, of, china, have, a, to, in, and, animals"
33692,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.104651163,"the, different, they, with, that, in, which, can, virus"
33693,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.104651163,"bat, from, in, the, by, collected, china, all, species"
33694,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.104651163,"to, the, have, in, of, and, animals, a, china"
33695,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.104651163,"in, the, and, are, to, suggesting, that, these, may"
33696,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.104651163,"the, of, bat, to, are, a, cluster, with, that"
33697,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.104651163,"of, and, that, humans,, a, in, human, as, to"
33698,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.104575163,"to, the, were, for, zoonotic, and, not, in, of, high, had, that, sars-related, have, further, found"
33699,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.104575163,"and, of, the, have, to, in, were, not, had, high, found, further, that, for, sars-related, zoonotic"
33700,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.104477612,"the, of, from, to, (paguma, bat, and"
33701,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.104477612,"the, a, of, which, to, and, bat"
33702,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.104477612,"bats, are, as, the, of, and, host"
33703,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.104477612,"bats, are, the, as, of, and, host"
33704,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.104477612,"in, the, of, is, to, that, virus"
33705,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.104477612,"the, of, as, intermediate, from, humans, to"
33706,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.104477612,"that, transmission, from, to, intermediate, species, the"
33707,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.104477612,"can, virus, transmission, from, to, and, as"
33708,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.104477612,"in, the, a, coronavirus, from, that, for"
33709,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.104477612,"from, sars-cov-2, has, to, be, in, the"
33710,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.104477612,"sars-cov-2, in, a, animal, species, and, as"
33711,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.104477612,"been, found, in, and, are, to, have"
33712,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.104477612,"the, of, a, at, that, from, to"
33713,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.104477612,"the, by, that, sars-cov-2, and, from, a"
33714,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.104477612,"that, the, from, a, in, humans, and"
33715,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.104477612,"genomic, that, the, in, and, humans, of"
33716,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.104477612,"a, of, the, virus, was, from, market"
33717,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.104477612,"reservoir, and, was, the, that, sars-cov-2, in"
33718,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.104477612,"on, in, and, of, were, to, from"
33719,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.104477612,"from, in, the, of, a, sars-cov-2, animals"
33720,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.104477612,"in, the, from, a, of, sars-cov-2, animals"
33721,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.104477612,"a, of, the, also, that, have, to"
33722,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.104477612,"that, are, sars-cov-2, is, laboratory, it, an"
33723,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.104477612,"evidence, in, the, that, to, from, market"
33724,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.104477612,"of, a, virus, the, market, was, from"
33725,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.104477612,"the, were, likely, to, that, virus, in"
33726,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.104477612,"the, from, analysis, that, covid-19, to, wild"
33727,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.104477612,"the, were, that, virus, in, animals, and"
33728,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.104477612,"that, the, of, origins, but, a, to"
33729,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.104477612,"or, animals, in, the, market, have, origin."
33730,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.104477612,"we, evidence, that, in, the, emergence, of"
33731,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.104477612,"that, the, infected, have, market, animals, of"
33732,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.104477612,"and, to, of, that, have, a, infect"
33733,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.104477612,"a, of, that, by, the, to, virus"
33734,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.104477612,"and, the, its, was, in, from, a"
33735,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.104477612,"in, to, the, likely, virus, that, were"
33736,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.104477612,"the, and, in, animals, virus, that, were"
33737,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.104477612,"the, likely, natural, in, virus, to, that"
33738,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.104477612,"in, december, the, of, was, outbreak, and"
33739,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.104477612,"the, market, in, or, animals, have, origin."
33740,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.104477612,"have, the, of, infected, animals, market, that"
33741,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.104477612,"suggested, as, the, was, or, with, of"
33742,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.104477612,"to, sars-cov-2, a, the, and, it, that"
33743,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.104477612,"was, suggested, the, with, or, as, of"
33744,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.104477612,"at, the, and, rbd, found, bats, to"
33745,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.104477612,"was, with, and, which, to, at, the"
33746,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.104477612,"of, from, without, in, with, analysis, the"
33747,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.104477612,"the, of, to, human, natural, a, or"
33748,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.104477612,"to, or, be, with, of, and, bats"
33749,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.104477612,"a, the, from, by, that, sars-cov-2, and"
33750,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.104477612,"a, the, from, that, and, in, humans"
33751,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.104477612,"of, from, a, in, with, sars-cov-2, the"
33752,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.104477612,"in, the, a, coronavirus, that, from, for"
33753,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.104477612,"pangolin, in, the, that, protein, for, of"
33754,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.104477612,"however,, the, and, in, coronaviruses, that, of"
33755,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.104477612,"isolated, from, a, sars-cov-2, to, in, the"
33756,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.104477612,"in, the, and, that, part, of, pangolin"
33757,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.104477612,"the, of, viruses, a, human, and, to"
33758,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.104477612,"bats, natural, of, and, a, as, covs"
33759,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.104477612,"the, that, have, in, for, of, were, to, and, with, who, but, not, had"
33760,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.104477612,"from, intermediate, that, transmission, to, the, species"
33761,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.104477612,"analysis, of, the, from, in, with, without"
33762,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.104477612,"a, sars-cov-2, with, the, of, from, in"
33763,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.104477612,"in, the, and, of, collected, were, from"
33764,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.104477612,"not, by, the, of, that, been, a"
33765,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.104477612,"sars-cov-2, in, the, furin, cleavage, with, coronaviruses"
33766,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.104477612,"bats, the, found, to, at, rbd, and"
33767,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.104477612,"sars-cov-2, animal, a, as, and, in, species"
33768,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.104477612,"that, the, of, species, in, as, a"
33769,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.104477612,"the, that, of, with, and, in, also"
33770,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.104477612,"have, been, to, are, and, found, in"
33771,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.104477612,"of, market, in, that, positive, for, the"
33772,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.104477612,"a, it, that, the, sars-cov-2, and, to"
33773,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.104477612,"the, in, sars-cov-2, with, furin, cleavage, coronaviruses"
33774,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.104477612,"the, and, to, sars-cov-2, of, bat, as"
33775,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.104477612,"and, to, the, of, bats, likely, sars-cov-2"
33776,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.104477612,"that, a, the, of, but, to, origins"
33777,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.104477612,"in, a, of, species, that, the, as"
33778,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.104477612,"the, was, to, at, which, with, and"
33779,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.104477612,"the, natural, likely, to, that, virus, in"
33780,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.104477612,"the, by, to, is, of, bat, as"
33781,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.104477612,"to, closely, related, sars-cov-2,, the, of, is"
33782,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.104477612,"positive, the, market, that, of, in, for"
33783,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.104477612,"the, evidence, from, that, to, humans,, and"
33784,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.104477612,"of, virus, that, to, the, and, for"
33785,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.104477612,"to, the, of, from, as, intermediate, humans"
33786,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.104477612,"in, the, outbreak, was, december, and, of"
33787,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.104477612,"and, human, that, a, of, the, virus"
33788,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.104477612,"found, that, to, and, a, the, of"
33789,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.104477612,"and, of, the, have, to, who, in, but, were, not, with, had, that, for"
33790,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.104477612,"also, in, of, and, that, the, with"
33791,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.104477612,"its, and, the, was, from, a, in"
33792,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.104477612,"of, that, it, the, and, for, was"
33793,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.104477612,"that, or, be, the, for, sars-cov-2, its"
33794,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.104477612,"a, study, of, samples, from, in, sars-cov-2"
33795,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.104477612,"were, of, from, in, and, to, on"
33796,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.104477612,"evidence, the, that, in, to, from, market"
33797,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.104477612,"the, of, from, and, were, collected, in"
33798,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.104477612,"a, to, the, natural, of, human, or"
33799,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.104477612,"the, a, of, that, most, likely, to"
33800,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.104477612,"in, the, protein, of, pangolin, that, for"
33801,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.104477612,"the, that, of, natural, sars-cov-2, is, for"
33802,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.104477612,"the, of, and, coronaviruses, that, in, however,"
33803,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.104477612,"to, coronavirus, have, been, in, and, animals"
33804,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.104477612,"the, of, human, to, a, and, viruses"
33805,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.104477612,"to, the, that, covid-19, analysis, from, wild"
33806,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.104477612,"the, and, that, humans,, from, evidence, to"
33807,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.104477612,"of, the, that, genomic, and, in, humans"
33808,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.104477612,"for, the, of, and, that, virus, to"
33809,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.104477612,"and, the, it, that, was, for, of"
33810,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.104477612,"coronavirus, and, animals, to, in, have, been"
33811,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.104477612,"and, to, bats, be, of, with, or"
33812,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.104477612,"and, in, found, closely, related, the, bats"
33813,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.104477612,"can, from, as, virus, transmission, to, and"
33814,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.104477612,"to, the, of, and, from, bat, (paguma"
33815,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.104477612,"the, of, to, most, likely, a, that"
33816,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.104477612,"the, sars-cov-2, has, to, from, in, be"
33817,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.104477612,"the, to, sars-cov-2, isolated, in, from, a"
33818,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.104477612,"also, the, of, that, a, have, to"
33819,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.104477612,"the, sars-cov-2, reservoir, was, that, in, and"
33820,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.104477612,"have, a, that, infect, of, to, and"
33821,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.104477612,"the, that, of, not, been, by, a"
33822,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.104477612,"the, of, a, that, virus, human, and"
33823,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.104477612,"are, that, it, an, sars-cov-2, is, laboratory"
33824,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.104477612,"sars-cov-2, the, that, for, is, of, natural"
33825,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.104477612,"the, be, that, or, its, for, sars-cov-2"
33826,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.104477612,"in, a, of, were, found, to, that"
33827,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.104477612,"in, the, by, using, sars-cov-2, of, bat"
33828,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.104477612,"the, pangolin, in, and, that, part, of"
33829,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.104477612,"the, to, as, of, sars-cov-2, bat, and"
33830,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.104477612,"the, of, to, as, by, is, bat"
33831,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.104477612,"bat, of, sars-cov-2, by, using, the, in"
33832,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.104477612,"the, of, a, found, that, to, and"
33833,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.104477612,"that, the, of, in, emergence, evidence, we"
33834,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.104477612,"the, of, is, virus, in, that, to"
33835,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.104477612,"samples, of, sars-cov-2, in, study, from, a"
33836,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.104477612,"a, in, that, to, of, were, found"
33837,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.104477612,"a, in, to, suggesting, that, of, common"
33838,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.104477612,"of, bats, as, a, natural, covs, and"
33839,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.104477612,"the, bats, likely, to, of, sars-cov-2, and"
33840,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.104477612,"the, of, closely, related, to, sars-cov-2,, is"
33841,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.104477612,"bats, and, found, in, closely, related, the"
33842,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.104477612,"in, a, of, to, suggesting, that, common"
33843,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.104477612,"of, the, with, to, s, protein, potential"
33844,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.104477612,"the, ability, of, sars-cov-2, to, be, and"
33845,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.104477612,"with, the, s, protein, of, potential, to"
33846,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.104347826,"the, animals, in, a, of, is, on, most, that, virus, were, and"
33847,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.104347826,"not, several, a, of, have, zoonotic, and, the, to, from, reservoir, species"
33848,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.104347826,"a, the, of, and, in, on, animals, virus, that, were, is, most"
33849,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.104347826,"to, the, several, zoonotic, and, not, a, reservoir, of, species, from, have"
33850,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.104166667,"to, sars-cov-2, in, a, bat"
33851,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.104166667,"to, a, which, bat, in"
33852,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.104166667,"viruses, the, of, from, this"
33853,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.104166667,"from, of, and, the, humans"
33854,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.104166667,"and, the, of, arise, natural"
33855,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.104166667,"in, a, of, animal, species"
33856,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.104166667,"recent, of, identified, coronaviruses, four"
33857,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.104166667,"of, to, and, are, the"
33858,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.104166667,"that, were, and, animals, virus"
33859,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","identified numerous human–animal interactions that con- 

stitute emergence risk factors, for example bat tourism, wet 

markets, wildlife supply chains for human consumption,15 land 

management practices, and environmental perturbations.",0.104166667,"and, bat, that, human, emergence"
33860,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.104166667,"and, to, of, which, in"
33861,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.104166667,"from, the, bat, and, with"
33862,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.104166667,"of, have, that, sars-cov-2, by"
33863,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.104166667,"that, of, sars-cov-2, be, by"
33864,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.104166667,"including, coronaviruses, the, to, of"
33865,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.104166667,"of, sars-cov-2, been, that, the"
33866,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.104166667,"it, that, the, sars-cov-2, to"
33867,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.104166667,"sars-cov-2, a, is, in, bat"
33868,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.104166667,"the, of, sars-cov-2, and, other"
33869,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.104166667,"the, in, that, was, by"
33870,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.104166667,"of, the, are, those, a"
33871,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.104166667,"the, of, a, viral, and"
33872,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.104166667,"a, sars-cov-2, and, with, virus"
33873,"identified numerous human–animal interactions that con- 

stitute emergence risk factors, for example bat tourism, wet 

markets, wildlife supply chains for human consumption,15 land 

management practices, and environmental perturbations.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.104166667,"that, emergence, bat, human, and"
33874,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.104166667,"the, have, that, sars-cov-2, to"
33875,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.104166667,"the, including, and, a, of"
33876,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.104166667,"and, human, that, the, virus"
33877,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.104166667,"ratg13, the, bat, to, sequence"
33878,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.104166667,"were, more, that, in, and"
33879,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.104166667,"of, protein, as, in, pangolin"
33880,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.104166667,"phylogenetic, analysis, that, which, and"
33881,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.104166667,"analysis, of, that, similar, and"
33882,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.104166667,"between, and, transmission, of, sars-cov-2"
33883,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.104166667,"to, sars-cov, and, mers-cov, the"
33884,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.104166667,"the, of, covs, to, and"
33885,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.104166667,"in, of, sars-cov-2, to, with"
33886,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.104166667,"the, of, ecosystem, that, its"
33887,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.104166667,"that, sars-cov-2, have, and, the"
33888,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.104166667,"that, have, origin, can, and"
33889,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.104166667,"the, have, animal, to, and"
33890,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.104166667,"the, of, to, that, its"
33891,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.104166667,"the, of, its, ecosystem, that"
33892,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.104166667,"its, in, the, of, that"
33893,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.104166667,"after, the, of, most, as"
33894,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.104166667,"the, that, a, virus, in"
33895,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.104166667,"in, the, of, were, intermediate"
33896,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.104166667,"of, sars-cov-2, from, the, for"
33897,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.104166667,"the, of, to, as, intermediate"
33898,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.104166667,"the, in, and, wuhan, of"
33899,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.104166667,"is, the, to, in, wuhan"
33900,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.104166667,"is, to, likely, in, the"
33901,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.104166667,"the, of, that, likely, to"
33902,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.104166667,"is, sars-cov-2, a, the, of"
33903,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.104166667,"a, and, to, sars-cov-2, the"
33904,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.104166667,"a, to, sars-cov-2, the, and"
33905,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.104166667,"the, has, been, bats, of"
33906,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.104166667,"the, of, mers-cov, hosts, and"
33907,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.104166667,"the, sars-cov, and, mers-cov, to"
33908,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.104166667,"the, that, hosts, for, virus"
33909,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.104166667,"of, the, genomic, with, only"
33910,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.104166667,"the, to, in, wuhan, is"
33911,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.104166667,"the, to, from, in, is"
33912,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.104166667,"to, is, which, at, the"
33913,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.104166667,"is, sars-cov-2, a, the, from"
33914,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.104166667,"a, sars-cov-2, is, the, to"
33915,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.104166667,"the, of, to, coronaviruses, including"
33916,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.104166667,"and, to, of, which, the"
33917,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.104166667,"in, spread, the, animals, to"
33918,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.104166667,"other, was, to, and, in"
33919,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.104166667,"other, the, and, in, to"
33920,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.104166667,"from, in, humans, the, animals"
33921,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.104166667,"that, the, of, bat, in"
33922,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.104166667,"of, the, with, bat, that"
33923,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.104166667,"the, are, and, transmitted, to"
33924,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.104166667,"that, the, coronaviruses, are, from"
33925,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.104166667,"the, for, and, to, in"
33926,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.104166667,"coronavirus, in, the, are, with"
33927,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.104166667,"the, are, transmitted, to, and"
33928,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.104166667,"has, been, bats, the, of"
33929,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.104166667,"the, is, of, evidence, to"
33930,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.104166667,"the, is, even, to, of"
33931,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.104166667,"in, the, a, that, and"
33932,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.104166667,"in, one, the, that, a"
33933,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.104166667,"a, the, by, that, origin"
33934,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.104166667,"that, the, virus, who, a"
33935,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.104166667,"the, by, was, a, who"
33936,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.104166667,"sars-cov-2, species, and, from, animal"
33937,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.104166667,"a, and, been, in, bat"
33938,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.104166667,"a, sars-cov-2, the, of, from"
33939,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.104166667,"the, of, to, a, as"
33940,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.104166667,"the, that, have, and, sars-cov-2"
33941,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.104166667,"the, was, from, of, bat"
33942,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.104166667,"that, the, of, was, and"
33943,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.104166667,"of, these, was, from, bat"
33944,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.104166667,"of, from, pangolins, and, sars-cov-2"
33945,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.104166667,"of, sars-cov-2, pangolins, from, and"
33946,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.104166667,"viruses, from, of, this, the"
33947,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.104166667,"the, to, this, that, of"
33948,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.104166667,"that, are, the, sars-cov-2, by, in, this, of, origin, and"
33949,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.104166667,"the, of, host, for, from"
33950,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.104166667,"from, at, sars-cov-2, the, of"
33951,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.104166667,"sars-cov-2, the, and, that, of"
33952,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.104166667,"to, the, that, and, be"
33953,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.104166667,"of, sars-cov-2, to, be, that"
33954,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.104166667,"we, the, in, related, that"
33955,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.104166667,"the, and, in, of, is"
33956,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.104166667,"is, origin, the, and, this"
33957,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.104166667,"in, a, of, with, origin"
33958,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.104166667,"by, virus, the, was, of"
33959,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.104166667,"the, repeated, in, and, of"
33960,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.104166667,"the, in, and, hosts, of"
33961,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.104166667,"and, likely, that, sars-cov-2, animal"
33962,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.104166667,"and, a, in, their, an"
33963,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.104166667,"to, sars-cov-2, in, from, of"
33964,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.104166667,"the, to, and, a, very"
33965,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.104166667,"and, very, to, the, of"
33966,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.104166667,"a, sars-cov-2, with, that, zoonotic"
33967,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.104166667,"that, of, the, huanan, market,"
33968,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.104166667,"the, of, a, including, and"
33969,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.104166667,"the, of, sars-cov-2, and, but"
33970,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.104166667,"sars-cov-2, a, the, and, an"
33971,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.104166667,"the, in, spread, to, animals"
33972,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.104166667,"the, a, one, that, in"
33973,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.104166667,"suggests, that, the, sars-cov-2, a"
33974,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.104166667,"such, been, by, to, the, evidence, of, natural, has, is"
33975,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.104166667,"was, in, and, to, other"
33976,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.104166667,"and, other, viruses, to, in"
33977,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.104166667,"that, is, sars-cov-2, laboratory, engineered"
33978,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.104166667,"the, wiv, was, to, that, and, would, by, sars, in, of, coronavirus, known, at, its"
33979,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.104166667,"the, was, not, to, have, it, would, that, in, of"
33980,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.104166667,"that, the, evidence, a, to"
33981,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.104166667,"to, as, genetic, the, genome"
33982,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.104166667,"the, from, that, to, a"
33983,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.104166667,"to, a, genome, from, in"
33984,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.104166667,"the, is, to, and, that"
33985,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.104166667,"that, the, likely, of, sars-cov-2"
33986,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.104166667,"the, that, was, to, virus"
33987,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.104166667,"the, that, a, virus, coronavirus"
33988,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.104166667,"animals, and, that, virus, were"
33989,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.104166667,"the, virus, that, from, and"
33990,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.104166667,"animals, is, the, virus, and"
33991,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.104166667,"of, and, have, that, to"
33992,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.104166667,"have, that, and, to, a"
33993,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.104166667,"and, that, of, to, species"
33994,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.104166667,"of, and, different, a, species"
33995,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.104166667,"origin, can, that, have, and"
33996,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.104166667,"from, in, which, that, human"
33997,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.104166667,"coronavirus, from, very, to, and"
33998,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.104166667,"the, a, to, very, and"
33999,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.104166667,"the, of, was, to, as"
34000,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.104166667,"in, a, of, the, with"
34001,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.104166667,"a, of, the, in, wuhan,"
34002,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.104166667,"the, group, of, virus, to"
34003,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.104166667,"that, the, of, this, been"
34004,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.104166667,"that, the, of, virus, to"
34005,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.104166667,"and, the, of, also, to, as, they, other, this, in"
34006,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.104166667,"in, published, the, journal, of"
34007,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.104166667,"in, the, of, first, and"
34008,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.104166667,"coronavirus, to, is, which, the"
34009,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.104166667,"the, of, that, an, is"
34010,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.104166667,"to, as, is, sars-cov-2, the"
34011,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.104166667,"bats, intermediate, and, the, from"
34012,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.104166667,"that, from, the, and, virus"
34013,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.104166667,"of, the, that, coronavirus, to"
34014,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.104166667,"a, for, 99%, with, the"
34015,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.104166667,"pangolin, similarity, to, sars-cov-2, the"
34016,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.104166667,"humans, the, and, sars-cov-2, infected"
34017,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.104166667,"the, a, to, of, and"
34018,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.104166667,"analysis, of, the, virus, and"
34019,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.104166667,"a, of, sars-cov-2, to, that"
34020,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.104166667,"of, and, the, intermediate, hosts"
34021,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.104166667,"that, of, sars-cov-2, have, by"
34022,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.104166667,"and, the, was, transmitted, to"
34023,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.104166667,"the, to, that, and, humans"
34024,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.104166667,"and, are, to, the, a"
34025,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.104166667,"the, and, was, transmitted, to"
34026,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.104166667,"and, virus, the, was, in"
34027,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.104166667,"in, to, the, from, and"
34028,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.104166667,"and, are, a, in, the"
34029,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.104166667,"who, a, that, the, virus"
34030,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.104166667,"have, a, that, to, and"
34031,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.104166667,"the, and, animals, virus, is"
34032,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.104166667,"bats, are, to, the, of"
34033,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.104166667,"in, was, to, of, the"
34034,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.104166667,"to, been, in, that, covid-19"
34035,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.104166667,"and, that, were, in, more"
34036,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.104166667,"the, and, that, to, humans"
34037,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.104166667,"that, the, and, is, to"
34038,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.104166667,"in, animal, and, that, the"
34039,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.104166667,"that, and, to, the, in"
34040,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.104166667,"in, the, and, to, that"
34041,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.104166667,"of, the, huanan, seafood, market,"
34042,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.104166667,"cov, with, bat, the, and"
34043,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.104166667,"of, and, that, the, bats"
34044,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.104166667,"the, and, bats, is, to"
34045,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.104166667,"is, that, the, of, virus"
34046,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.104166667,"and, of, is, the, to"
34047,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.104166667,"the, sars-cov, and, is, to"
34048,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.104166667,"the, and, to, is, sars-"
34049,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.104166667,"is, the, reservoir, for, to"
34050,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.104166667,"was, the, patients, with, seafood, market, were, or, a, of"
34051,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.104166667,"the, however,, not, but, only"
34052,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.104166667,"a, the, seafood, with, was, market, of, were, patients, or"
34053,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.104166667,"a, that, the, of, animals"
34054,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.104166667,"the, of, only, with, genomic"
34055,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.104166667,"the, of, with, that, bat"
34056,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.104166667,"however,, the, not, only, but"
34057,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.104166667,"that, a, bat, of, with"
34058,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.104166667,"that, bats, the, a, bat"
34059,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.104166667,"to, a, the, ace2, for"
34060,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.104166667,"with, bat, cov, and, the"
34061,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.104166667,"the, that, coronaviruses, are, from"
34062,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.104166667,",, coronaviruses, the, that, of"
34063,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.104166667,"the, that, are, of, it"
34064,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.104166667,"the, virus, have, to, and"
34065,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.104166667,"are, those, of, the, a"
34066,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.104166667,"protein, of, in, as, pangolin"
34067,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.104166667,"the, of, in, closely, to"
34068,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.104166667,"the, is, of, in, also"
34069,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.104166667,"the, is, also, in, coronaviruses"
34070,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.104166667,"the, to, have, and, animal"
34071,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.104166667,"have, the, and, virus, to"
34072,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.104166667,"in, may, the, animal, from, market, virus, to, infected, and"
34073,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.104166667,"sars-cov-2, from, animal, and, species"
34074,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.104166667,"be, that, of, sars-cov-2, by"
34075,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.104166667,"transmission, of, sars-cov-2, between, and"
34076,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.104166667,"sars-cov-2, animal, likely, that, and"
34077,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.104166667,"that, species, of, to, and"
34078,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.104166667,"that, animal, of, is, by"
34079,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.104166667,"closest, bat, coronavirus, the, genome"
34080,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.104166667,"the, genomes, bat, and, coronavirus"
34081,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.104166667,"of, virus, the, was, by"
34082,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.104166667,"and, the, virus, was, in"
34083,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.104166667,"analysis, of, the, and, virus"
34084,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.104166667,"the, of, virus, to, with"
34085,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.104166667,"the, sequences,, bats, from, to"
34086,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.104166667,"that, to, and, are, the"
34087,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.104166667,"the, pangolin, to, be, intermediate"
34088,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.104166667,"the, or, pangolin, of, sars-"
34089,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.104166667,"the, of, to, that, coronavirus"
34090,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.104166667,"coronavirus, and, very, from, to"
34091,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.104166667,"the, of, as, from, and"
34092,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.104166667,"the, of, that, to, virus"
34093,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.104166667,"the, that, novel, virus, covid-19"
34094,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.104166667,"sars-cov-2, and, the, that, originated"
34095,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.104166667,"on, genome, from, the, and"
34096,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.104166667,"to, sars-cov-2, in, protein, ace2"
34097,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.104166667,"and, virus, the, covid-19, of"
34098,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.104166667,"to, the, market, in, that"
34099,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.104166667,"a, that, humans, to, the"
34100,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.104166667,"studies, from, in, the, and"
34101,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.104166667,"sars-cov-2, with, and, a, virus"
34102,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.104166667,"the, a, of, sars-cov, and"
34103,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.104166667,"s, protein, sequence, that, of"
34104,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.104166667,"the, sars-cov-2, and, of, other"
34105,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.104166667,"the, of, humans, hosts, and"
34106,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.104166667,"are, to, of, the, bats"
34107,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.104166667,"the, of, to, most, likely"
34108,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.104166667,"of, the, huanan, market,, that"
34109,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.104166667,"huanan, seafood, market,, the, of"
34110,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.104166667,"the, of, samples, from, that"
34111,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.104166667,"of, that, the, which, includes"
34112,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.104166667,"sars-cov-2, to, be, 96.2%, bat"
34113,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.104166667,"to, the, be, pangolin, intermediate"
34114,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.104166667,"from, with, sars-cov-2, the, sequence"
34115,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.104166667,"in, to, of, the, was"
34116,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.104166667,"the, of, to, a, that"
34117,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.104166667,"to, that, the, be, of"
34118,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.104166667,"of, the, a, that, naturally"
34119,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.104166667,"the, huanan, market, at, in"
34120,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.104166667,"from, the, bat, was, of"
34121,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.104166667,"of, sars-cov-2, from, in, to"
34122,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.104166667,"the, in, a, to, from"
34123,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.104166667,"and, in, the, of, repeated"
34124,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.104166667,"a, that, on, the, for"
34125,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.104166667,"and, pangolin, the, that, in"
34126,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.104166667,"on, in, the, of, and"
34127,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.104166667,"in, the, of, that, pangolin"
34128,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.104166667,"polybasic, cleavage, in, coronaviruses, of"
34129,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.104166667,"such, have, been, in, of"
34130,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.104166667,"the, of, from, as, and"
34131,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.104166667,"in, the, of, that, its"
34132,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.104166667,"to, in, ratg13, the, ("
34133,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.104166667,"the, sequence, of, to, in"
34134,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.104166667,"a, the, leak, by, to"
34135,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.104166667,"the, and, to, covs, of"
34136,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.104166667,"to, the, as, a, of"
34137,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.104166667,"of, to, which, the, these"
34138,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.104166667,"been, a, and, in, bat"
34139,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.104166667,"the, of, bat, in, a"
34140,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.104166667,"sars-cov-2, and, the, of, in"
34141,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.104166667,"sars-cov-2, the, and, in, of"
34142,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.104166667,"the, for, of, from, host"
34143,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.104166667,"the, a, for, of, as, bats,, with, bats, were, and"
34144,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.104166667,"the, for, a, 99%, with"
34145,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.104166667,"the, a, possible, intermediate, for"
34146,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.104166667,"the, live, animals, to, in, markets, for, of, with, that, were, animal, traders, yunnan, and"
34147,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.104166667,"a, to, the, may, human"
34148,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.104166667,"the, of, or, to, that, there, no, covid-19, is, sars-cov-2"
34149,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.104166667,"the, sars-cov-2, was, to, virus"
34150,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.104166667,"that, sars-cov-2, to, the, in"
34151,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.104166667,"to, that, in, human, than"
34152,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.104166667,"the, is, that, in, of, 2, to, with, a, an"
34153,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.104166667,"of, the, in, were, with"
34154,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.104166667,"a, of, with, bat, that"
34155,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.104166667,"the, to, that, sars-cov-2, is"
34156,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.104166667,"is, that, of, animal, by"
34157,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.104166667,"of, the, in, to, sars-cov-2"
34158,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.104166667,"the, in, found, to, ratg13"
34159,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.104166667,"and, the, from, to, in"
34160,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.104166667,"and, from, of, the, humans"
34161,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.104166667,"the, reported, to, in, of"
34162,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.104166667,"with, the, and, from, bat"
34163,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.104166667,"the, with, from, and, bat"
34164,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.104166667,"at, ratg13, the, with, sars-cov-2"
34165,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.104166667,"with, the, s, protein, of"
34166,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.104166667,"sequence, s, protein, of, that"
34167,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.104166667,"sequence, with, the, sars-cov-2, in"
34168,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.104166667,"is, the, and, bats, to"
34169,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.104166667,"from, sequences,, bats, to, the"
34170,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.104166667,"found, the, ratg13, to, in"
34171,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.104166667,"a, the, ace2, for, to"
34172,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.104166667,"in, the, to, ratg13, ("
34173,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.104166667,"a, to, in, the, human"
34174,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.104166667,"the, can, be, these, of, to, such, as, and, et"
34175,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.104166667,"the, of, intermediate, hosts, and"
34176,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.104166667,"that, and, hosts, for, sars-cov-2"
34177,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.104166667,"however,, in, these, to, through"
34178,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.104166667,"the, sars-cov-2, to, infect, and"
34179,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.104166667,"to, contrast, that, sars-cov-2, the"
34180,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.104166667,"the, to, infect, and, sars-cov-2"
34181,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.104166667,"the, between, sars-cov-2, and, is"
34182,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.104166667,"evidence, the, that, a, to"
34183,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.104166667,"the, of, evidence, that, a"
34184,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.104166667,"the, of, were, in, with"
34185,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.104166667,"the, covid-19, of, to, in"
34186,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.104166667,"at, the, in, to, animal"
34187,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.104166667,"that, of, samples, from, the"
34188,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.104166667,"from, the, was, time, that, this, in, of, taken, at"
34189,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.104166667,"that, the, of, intermediate, host"
34190,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.104166667,"sars-cov-2, the, of, from, in"
34191,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.104166667,"the, a, from, sars-cov-2, is"
34192,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.104166667,"of, the, covid-19, in, to"
34193,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.104166667,"the, of, are, more, likely"
34194,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.104166667,"sars-cov-2, and, bat, to, the"
34195,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.104166667,"sars-cov-2, malayan, and, of, as"
34196,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.104166667,"in, the, to, and, for"
34197,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.104166667,"other, to, and, viruses, in"
34198,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.104166667,"to, the, of, and, bat"
34199,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.104166667,"the, of, to, and, bat"
34200,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.104166667,"in, to, of, the, and"
34201,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.104166667,"a, different, species, of, and"
34202,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.104166667,"are, and, the, a, in"
34203,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.104166667,"the, are, in, a, of, viruses, southern, china,, by, and"
34204,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.104166667,"of, similar, the, bat, and"
34205,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.104166667,"a, of, bat, region, in"
34206,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.104166667,"the, closely, to, in, covid-19"
34207,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.104166667,"recombination, that, in, the, of"
34208,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.104166667,"other, as, also, the, of, and, in, they, this, to"
34209,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.104166667,"the, that, are, also, with, of, is, they, as, for"
34210,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.104166667,"from, a, to, sars-cov-2,, which"
34211,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.104166667,"is, at, the, to, which"
34212,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.104166667,"genetic, the, genome, as, to"
34213,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.104166667,"the, which, is, to, coronavirus"
34214,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.104166667,"to, sars-cov-2, is, the, as"
34215,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.104166667,"the, genome, closest, bat, coronavirus"
34216,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.104166667,"the, in, which, was, by"
34217,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.104166667,"the, sars-cov-2, with, other, to"
34218,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.104166667,"to, the, sars-, and, is"
34219,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.104166667,"are, to, the, and, that"
34220,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.104166667,"the, of, to, with, that"
34221,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.104166667,"in, than, to, that, human"
34222,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.104166667,"a, of, their, the, viruses"
34223,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.104166667,"of, and, the, for, sars-cov-2"
34224,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.104166667,"the, most, after, as, of"
34225,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.104166667,"group, of, to, the, virus"
34226,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.104166667,"is, virus, to, the, most"
34227,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.104166667,"the, of, is, to, virus"
34228,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.104166667,"the, covid-19, in, closely, to"
34229,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.104166667,"the, is, known, covid-19, in"
34230,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.104166667,"infected, humans, and, the, sars-cov-2"
34231,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.104166667,"that, the, in, humans, and"
34232,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.104166667,"who, a, the, was, by"
34233,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.104166667,"the, to, a, of, with, on, was, by, and, market"
34234,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.104166667,"the, virus, from, animal, in, market, infected, to, and, may"
34235,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.104166667,"the, related, to, after, for, a, from, animals, is, also"
34236,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.104166667,"the, of, and, this, novel, coronavirus, more, from, viruses, bats"
34237,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.104166667,"the, that, wiv, was, known, to, sars, coronavirus, in, by, its, of, and, would, at"
34238,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.104166667,"the, of, in, taken, from, that, this, was, at, time"
34239,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.104166667,"with, the, of, bats, were, as, a, for, bats,, and"
34240,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.104166667,"and, of, the, to, markets, live, animals, animal, traders, in, were, with, that, yunnan, for"
34241,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.104166667,"of, and, southern, china,, viruses, are, by, a, in, the"
34242,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.104166667,"the, by, was, a, market, and, to, of, on, with"
34243,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.104166667,"that, of, to, an, is, a, in, with, the, 2"
34244,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.104166667,"not, only, a, of, but, have, and, the, to, 41"
34245,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.104166667,"similarly,, the, and, a, in, to, that, not, of, but"
34246,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.104166667,"there, is, no, that, the, of, to, sars-cov-2, or, covid-19"
34247,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.104166667,"the, of, were, huanan, in"
34248,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.104166667,"the, to, evidence, of, is"
34249,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.104166667,"the, of, in, is, also"
34250,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.104166667,"is, also, in, the, of"
34251,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.104166667,"is, the, known, in, covid-19"
34252,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.104166667,"that, the, a, to, humans"
34253,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.104166667,"the, on, that, for, a"
34254,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.104166667,"the, most, virus, to, is"
34255,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","expended to make the simple point 

that COVID-19 had a natural origin.",0.104166667,"to, the, that, a, covid-19"
34256,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.104166667,"that, were, in, to, and"
34257,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.104166667,"sars-cov-2, and, to, that, in"
34258,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.104166667,"a, and, the, of, in"
34259,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.104166667,"a, its, in, the, that"
34260,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.104166667,"to, the, most, likely, of"
34261,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.104166667,"the, of, its, to, that"
34262,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.104166667,"its, the, of, that, to"
34263,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.104166667,"that, human, in, which, from"
34264,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.104166667,"to, the, may, a, human"
34265,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.104166667,"to, sars-cov-2,, which, from, a"
34266,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.104166667,",, that, the, of, coronaviruses"
34267,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.104166667,"sars-cov-2, to, ace2, protein, in"
34268,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.104166667,"and, arise, of, natural, the"
34269,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.104166667,"a, the, that, sars-cov-2, during"
34270,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.104166667,"of, the, sars-cov-2, in, pangolins"
34271,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.104166667,"this, the, sars-cov-2, we, that"
34272,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.104166667,"sars-cov-2, and, a, the, of"
34273,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.104166667,"in, related, we, that, the"
34274,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.104166667,"is, and, of, the, in"
34275,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.104166667,"of, that, sars-cov-2, the, and"
34276,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.104166667,"polybasic, cleavage, in, of, coronaviruses"
34277,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.104166667,"we, observed, of, sars-cov-2, and"
34278,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.104166667,"that, the, of, including, and"
34279,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.104166667,"a, the, that, in, virus"
34280,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.104166667,"the, virus, a, coronavirus, that"
34281,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.104166667,"that, the, novel, covid-19, virus"
34282,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.104166667,"a, virus, that, the, in"
34283,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.104166667,"in, the, of, sequence, to"
34284,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.104166667,"sars-cov, cov, and, more, than"
34285,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.104166667,"and, phylogenetic, analysis, that, which"
34286,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.104166667,"a, possible, intermediate, for, the"
34287,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.104166667,"the, is, bat, from, species"
34288,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.104166667,"from, animal, as, the, for"
34289,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.104166667,"wuhan, the, in, of, and"
34290,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.104166667,"and, in, the, of, hosts"
34291,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.104166667,"however,, in, to, these, through"
34292,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.104166667,"that, was, by, the, in"
34293,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.104166667,"in, the, of, that, been"
34294,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.104166667,"was, in, by, which, the"
34295,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.104166667,"and, analysis, that, similar, of"
34296,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.104166667,"of, and, similar, bat, the"
34297,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.104166667,"the, was, and, to, of"
34298,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.104166667,"virus, is, similar, the, of"
34299,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.104166667,"been, to, that, covid-19, in"
34300,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.104166667,"were, of, in, the, huanan"
34301,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.104166667,"the, that, was, to, have, in, of, it, would, not"
34302,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.104166667,"in, of, reported, to, the"
34303,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.104166667,"of, the, in, that, with"
34304,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.104166667,"the, natural, reservoir, of, is"
34305,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.104166667,"the, that, is, of, natural"
34306,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.104166667,"the, and, bats, may, of"
34307,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.104166667,"bat, the, host, of, and"
34308,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.104166667,"bats, of, and, to, be"
34309,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.104166667,"be-, tween, and, the, in"
34310,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.104166667,"these, such, as, and, the, of, to, et, can, be"
34311,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.104166667,"the, of, first, and, in"
34312,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.104166667,"the, in, pangolins, of, sars-cov-2"
34313,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.104166667,"and, origin, of, the, is"
34314,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.104166667,"the, sars-cov-2, and, guangdong, is"
34315,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.104166667,"sars-cov-2, and, the, origin, of"
34316,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.104166667,"from, the, sequence, with, sars-cov-2"
34317,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.104166667,"of, virus, is, similar, the"
34318,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.104166667,"the, amino, acid, of, is"
34319,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.104166667,"from, bats, and, the, intermediate"
34320,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.104166667,"a, of, and, that, the"
34321,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.104166667,"that, the, animals, a, of"
34322,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.104166667,"and, a, of, is, the"
34323,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.104166667,"after, the, animals, from, for, also, to, a, is, related"
34324,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.104166667,"the, only, have, of, 41, to, and, a, but, not"
34325,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.104166667,"the, hosts, of, and, mers-cov"
34326,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.104166667,"that, sars-cov-2, a, bat, and"
34327,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.104166667,"the, origin, by, a, that"
34328,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.104166667,"the, to, by, a, leak"
34329,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.104166667,"in, the, coronavirus, are, with"
34330,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.104166667,"the, an, is, that, of"
34331,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.104166667,"sars-cov-2, the, of, that, been"
34332,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.104166667,"the, from, animal, as, for"
34333,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.104166667,"sars-cov-2, bat, be, to, 96.2%"
34334,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.104166667,"virus, the, and, that, human"
34335,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.104166667,"of, the, origin, is, and"
34336,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.104166667,"that, the, virus, origin, of"
34337,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.104166667,"it, that, the, of, are"
34338,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.104166667,"the, of, also, are, as, they, with, that, for, is"
34339,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.104166667,"and, of, the, viral, a"
34340,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.104166667,"to, such, the, by, of, is, has, been, evidence, natural"
34341,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.104166667,"have, been, in, of, such"
34342,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.104166667,"the, that, to, be, and"
34343,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.104166667,"this, is, and, origin, the"
34344,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.104166667,"of, the, to, with, sars-cov-2"
34345,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.104166667,"the, of, to, sars-cov-2, with"
34346,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.104166667,"with, other, to, sars-cov-2, the"
34347,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.104166667,"similarity, of, sars-cov-2, the, to"
34348,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.104166667,"we, observed, sars-cov-2, and, of"
34349,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.104166667,"the, of, to, which, these"
34350,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.104166667,"the, in, is, also, coronaviruses"
34351,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.104166667,"origin, of, the, this, by, that, sars-cov-2, and, are, in"
34352,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.104166667,"in, with, the, by, and, to, that, sars-cov-2, of, are"
34353,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.104166667,"and, in, to, be, that, the, of, are, natural, sars-cov-2"
34354,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.104166667,"the, that, a, to, from"
34355,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.104166667,"the, and, genomes, bat, coronavirus"
34356,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.104166667,"bat, that, and, sars-cov-2, a"
34357,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.104166667,"sars-cov-2, to, the, bat, pangolin"
34358,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.104166667,"sars-cov-2, and, that, hosts, for"
34359,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.104166667,"hosts, that, virus, for, the"
34360,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.104166667,"sars-cov-2, the, that, to, it"
34361,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.104166667,"to, the, reservoir, is, for"
34362,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.104166667,"a, the, bat, that, bats"
34363,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.104166667,"that, of, the, which, includes"
34364,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.104166667,"the, of, in, wuhan,, a"
34365,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.104166667,"in, the, of, sars-cov-2, at"
34366,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.104166667,"to, bat, in, a, which"
34367,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.104166667,"these, from, bat, was, of"
34368,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.104166667,"in, a, genome, to, from"
34369,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.104166667,"of, to, a, bat, genome"
34370,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.104166667,"a, and, their, in, an"
34371,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.104166667,"be, in, that, sars-cov-2, for"
34372,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.104166667,"the, of, sars-cov-2, with, by"
34373,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.104166667,"the, that, in, with, of"
34374,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.104166667,"that, in, and, the, for"
34375,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.104166667,"ratg13, at, the, with, sars-cov-2"
34376,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.104166667,"the, that, sars-cov-2, we, this"
34377,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.104166667,"that, sars-cov-2, are, cov, the"
34378,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.104166667,"has, been, the, of, and"
34379,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.104166667,"this, of, the, that, been"
34380,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.104166667,"of, the, from, bats, coronavirus, this, novel, and, viruses, more"
34381,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.104166667,"the, that, sars-cov-2, originated, and"
34382,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.104166667,"the, pangolin, in, and, that"
34383,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.104166667,"be-, tween, and, in, the"
34384,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.104166667,"the, to, in, is, likely"
34385,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.104166667,"the, sars-cov-2, to, bat, pangolin"
34386,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.104166667,"that, are, the, sars-cov-2, to, by, with, in, of, and"
34387,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.104166667,"sars-, the, of, or, pangolin"
34388,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.104166667,"the, sars-cov-2, is, and, between"
34389,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.104166667,"the, sars-cov-2, is, guangdong, and"
34390,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.104166667,"that, likely, the, of, sars-cov-2"
34391,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.104166667,"that, sars-cov-2, similarity, the, we"
34392,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.104166667,"with, the, and, sars-cov-2, bat"
34393,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.104166667,"sars-cov-2, and, bat, ratg13, the"
34394,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.104166667,"the, that, as, origin, for"
34395,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.104166667,"on, the, genome, and, from"
34396,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.104166667,"studies, the, from, in, and"
34397,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.104166667,"the, in, and, on, of"
34398,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.104166667,"of, the, sars-cov-2, origin, and"
34399,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.104166667,"cov, the, sars-cov-2, that, are"
34400,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.104166667,"the, of, that, to, likely"
34401,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.104166667,"the, likely, are, more, of"
34402,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.104166667,"of, to, a, genome, bat"
34403,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.104166667,"the, is, of, with, and"
34404,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.104166667,"the, but, and, of, sars-cov-2"
34405,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.104166667,"the, with, of, sars-cov-2, is"
34406,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.104166667,"by, of, with, the, sars-cov-2"
34407,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.104166667,"that, the, of, in, recombination"
34408,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.104166667,"the, that, of, and, in"
34409,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.104166667,"a, and, the, from, in"
34410,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.104166667,"a, and, sars-cov, the, of"
34411,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.104166667,"including, the, and, that, of"
34412,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.104166667,"more, than, sars-cov, and, cov"
34413,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.104166667,"the, sars-cov-2, and, to, in"
34414,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.104166667,"the, in, and, that, for"
34415,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.104166667,"the, pangolin, in, that, of"
34416,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.104166667,"of, sars-cov-2, at, the, in"
34417,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.104166667,"of, bats, to, sars-cov-2, the"
34418,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.104166667,"that, the, to, contrast, sars-cov-2"
34419,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.104166667,"that, origin, of, the, virus"
34420,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.104166667,"we, that, the, similarity, sars-cov-2"
34421,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.104166667,"the, to, be, sars-cov-2,, of"
34422,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.104166667,"the, of, to, with, a"
34423,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.104166667,"a, virus, with, to, the"
34424,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.104166667,"in, the, was, that, for"
34425,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.104166667,"that, the, as, for, origin"
34426,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.104166667,"host, of, and, the, bat"
34427,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.104166667,"and, of, sars-cov-2, an, the"
34428,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.104166667,"the, an, and, a, sars-cov-2"
34429,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.104166667,"that, the, of, evidence, a"
34430,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.104166667,"that, a, sars-cov-2, the, during"
34431,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.104166667,"that, be, for, sars-cov-2, in"
34432,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.104166667,"the, to, even, of, is"
34433,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.104166667,"identified, of, coronaviruses, four, recent"
34434,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.104166667,"region, of, bat, a, in"
34435,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.104166667,"with, sars-cov-2, to, in, of"
34436,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.104166667,"that, to, be, sars-cov-2, of"
34437,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.104166667,"with, a, origin, of, in"
34438,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.104166667,"with, a, that, sars-cov-2, zoonotic"
34439,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.104166667,"a, of, to, that, sars-cov-2"
34440,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.104166667,"that, of, in, for, sars-cov-2"
34441,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.104166667,"of, the, that, a, naturally"
34442,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.104166667,"animal, to, in, at, the"
34443,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.104166667,"that, are, the, sars-cov-2, to, be, in, of, natural, and"
34444,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.104166667,"the, to, bat, ratg13, sequence"
34445,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.104166667,"the, of, to, be, is"
34446,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.104166667,"bat, ratg13, is, the, than"
34447,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.104166667,"to, the, be, of, sars-cov-2,"
34448,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.104166667,"the, that, in, of, to, similarly,, and, a, but, not"
34449,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.104166667,"as, of, sars-cov-2, malayan, and"
34450,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.104166667,"of, to, the, suggesting, that"
34451,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.104166667,"s, protein, the, of, with"
34452,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.104166667,"the, of, that, intermediate, host"
34453,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.104166667,"is, the, amino, acid, of"
34454,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.104166667,"the, to, very, of, and"
34455,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.104166667,"sars-cov-2, the, and, coronaviruses, of"
34456,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.104166667,"bat, and, the, sars-cov-2, ratg13"
34457,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.104166667,"the, suggests, that, a, sars-cov-2"
34458,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.104166667,"that, engineered, sars-cov-2, is, laboratory"
34459,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.104,"the, from, and, were, in, of, a, as, to, that, infected, at, virus"
34460,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.104,"in, the, of, as, a, at, that, virus, from, infected, were, to, and"
34461,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.103896104,"in, the, of, as, was, a, infected, to"
34462,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.103896104,"sars-cov-2, has, a, origin, and, in, an, or"
34463,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.103896104,"he, of, sars-cov-2, has, not, that, the, a"
34464,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.103896104,"that, in, and, the, virus, new, for, of"
34465,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.103896104,"in, the, was, a, that, virus, from, sequence"
34466,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.103896104,"the, is, in, of, to, and, with, known"
34467,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.103896104,"that, the, of, and, receptor, ace2, as, a"
34468,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.103896104,"and, from, in, found, to, are, likely, sars-cov-2"
34469,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.103896104,"the, huanan, market, that, of, to, and, known"
34470,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.103896104,"the, huanan, market, that, in, cases, to, a"
34471,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.103896104,"the, of, in, middle, east, respiratory, syndrome, other"
34472,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.103896104,"an, from, wuhan, to, in, a, there, animal"
34473,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.103896104,"is, wuhan, that, in, to, a, covid-19, an"
34474,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.103896104,"other, in, middle, east, respiratory, syndrome, the, of"
34475,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.103896104,"that, the, of, market, in, to, were, a"
34476,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.103896104,"the, of, have, which, to, animal, and, was"
34477,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.103896104,"be, of, natural, the, and, with, to, sars-"
34478,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.103896104,"a, as, the, of, and, that, ace2, receptor"
34479,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.103896104,"the, of, intermediate, that, this, evidence, as, to"
34480,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.103896104,"to, sars-cov-2, result, of, the, and, it, that"
34481,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.103896104,"a, and, with, sars-cov-2, intermediate, hosts, in, the"
34482,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.103896104,"in, and, sars-cov-2, with, that, the, between, than"
34483,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.103896104,"and, the, of, to, it, that, sars-cov-2, result"
34484,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.103896104,"the, of, a, to, and, market, at, was"
34485,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.103896104,"the, of, that, as, intermediate, evidence, to, this"
34486,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.103896104,"a, collected, and, were, to, of, in, the"
34487,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.103896104,"to, the, in, and, evidence, that, or, for"
34488,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.103896104,"as, a, of, the, in, was, to, infected"
34489,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.103896104,"that, was, from, a, the, virus, sequence, in"
34490,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.103896104,"and, a, of, in, an, the, to, human"
34491,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.103896104,"there, in, wuhan, from, a, an, animal, to"
34492,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.103896104,"with, the, known, and, is, to, in, of"
34493,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.103896104,"the, huanan, market, that, known, to, and, of"
34494,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.103896104,"that, is, covid-19, in, wuhan, a, an, to"
34495,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.103896104,"the, of, and, were, collected, a, in, to"
34496,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.103896104,"in, with, the, and, that, is, of, are"
34497,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.103896104,"the, in, and, therefore, that, or, be, for"
34498,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.103896104,"sars-cov-2, origin, has, a, or, in, an, and"
34499,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.103896104,"the, of, and, have, animal, which, was, to"
34500,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.103896104,"the, was, a, at, market, and, to, of"
34501,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.103896104,"of, and, a, several, to, zoonotic, humans,, covs"
34502,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.103896104,"sars-cov-2, in, a, and, the, with, intermediate, hosts"
34503,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.103896104,"he, sars-cov-2, of, has, a, that, not, the"
34504,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.103896104,"bats, of, a, related, to, that, in, covs"
34505,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.103896104,"in, the, of, an, a, to, human, and"
34506,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.103896104,"for, the, and, that, in, evidence, or, to"
34507,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.103896104,"and, the, therefore, be, that, or, for, in"
34508,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.103896104,"that, and, sars-cov-2, than, the, between, in, with"
34509,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.103896104,"the, is, that, of, are, with, and, in"
34510,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.103896104,"of, for, virus, that, in, and, new, the"
34511,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.103896104,"covs, several, a, of, zoonotic, and, to, humans,"
34512,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.103896104,"a, in, that, related, to, of, covs, bats"
34513,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.103896104,"and, coron-, a, in, to, that, are, of"
34514,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.103896104,"in, to, sars-cov-2,, indicating, that, the, of, natural"
34515,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.103896104,"sars-cov-2, from, to, are, likely, and, found, in"
34516,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.103896104,"natural, of, the, in, to, sars-cov-2,, indicating, that"
34517,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.103896104,"are, of, and, a, coron-, to, that, in"
34518,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.103896104,"and, sars-, to, the, be, natural, of, with"
34519,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.103773585,"the, of, a, large, in, that, bats, and, or, virus,, asia"
34520,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.103773585,"with, and, accounted, for, of, or, that, were, more, infected, than"
34521,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.103773585,"for, the, of, and, that, virus, a, in, human, or, to"
34522,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.103773585,"and, the, would, that, or, for, of, sars-cov-2, in, a, published"
34523,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.103773585,"the, and, a, in, of, from, (rhinolophus, sequence, genome, isolated, identity"
34524,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.103773585,"the, of, a, in, to, that, with, and, virus, it, for"
34525,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.103773585,"the, team, was, to, a, similar, with, and, by, in, at"
34526,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.103773585,"for, with, to, the, market, in, of, a, tested, positive, animal"
34527,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.103773585,"of, evidence, that, the, is, a, from, animal, species, as, for"
34528,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.103773585,"that, may, by, a, of, virus, similar, to, and, the, for"
34529,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.103773585,"of, for, to, human, a, virus, or, that, in, and, the"
34530,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.103773585,"genome, a, sequence, identity, and, the, of, isolated, from, (rhinolophus, in"
34531,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.103773585,"a, large, of, and, that, the, virus,, or, in, bats, asia"
34532,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.103773585,"in, the, of, virus, for, it, to, that, with, and, a"
34533,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.103773585,"was, in, by, a, team, with, and, similar, to, at, the"
34534,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.103773585,"and, also, a, of, in, receptor, an, the, for, to, human"
34535,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.103773585,"a, virus, to, bats, large, of, and, are, as, on, markets"
34536,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.103773585,"a, of, market, in, animal, tested, positive, for, with, the, to"
34537,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.103773585,"of, more, than, and, that, accounted, for, were, infected, with, or"
34538,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.103773585,"sars-cov-2, of, for, a, would, published, or, that, in, and, the"
34539,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.103773585,"the, animal, of, from, that, for, as, species, a, is, evidence"
34540,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.103773585,"are, to, markets, a, of, as, large, on, bats, virus, and"
34541,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.103773585,"the, also, for, to, a, receptor, and, human, in, of, an"
34542,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.103773585,"may, the, of, that, for, virus, similar, to, by, a, and"
34543,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.103703704,"the, that, have, in, for, of, were, to, and, a, not, known, had, an"
34544,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.103703704,"to, the, were, for, known, and, not, a, in, of, had, that, have, an"
34545,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.103658537,"in, the, of, a, to, as, by, found, were, similar, and, that, sars, from, approximately, first, species"
34546,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.103658537,"in, the, first, sars, of, approximately, from, found, that, as, similar, to, species, were, by, a, and"
34547,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.103448276,"of, the, in, pangolins, from, and"
34548,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.103448276,"a, in, the, that, from, or"
34549,Bats are hosts of many coronaviruses,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.103448276,"are, many, coronaviruses"
34550,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.103448276,"and, of, the, viruses, human, 2"
34551,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.103448276,"of, in, coronaviruses"
34552,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.103448276,"of, a, in"
34553,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.103448276,"animal, species, in"
34554,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.103448276,"bat, coronaviruses, of"
34555,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.103448276,"in, bats, as"
34556,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.103448276,"in, to, coronaviruses"
34557,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.103448276,"and, in, bat"
34558,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.103448276,"and, to, sars-cov"
34559,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.103448276,"bats, and, of"
34560,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.103448276,"to, sars-cov-2, of, in, bats, and"
34561,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.103448276,"to, emerged, in"
34562,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.103448276,"are, the, sars-like"
34563,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.103448276,"genome, to, virus"
34564,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.103448276,"to, in, than"
34565,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.103448276,"in, virus, identical, to, more, than"
34566,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.103448276,"sars-cov-2, to, its"
34567,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.103448276,"is, for, a"
34568,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.103448276,"a, for, and"
34569,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.103448276,"from, to, the, which, may, human"
34570,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.103448276,"genetic, have, that, the, to, from"
34571,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.103448276,"coronavirus, from, is"
34572,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.103448276,"have, been, which"
34573,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.103448276,"the, of, and, have, that, sars-cov-2, an, which, to"
34574,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.103448276,"a, to, bat, the, of, sars-cov-2"
34575,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.103448276,"the, of, which, amino, acid, sars-cov-2"
34576,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.103448276,"and, the, of, which, site, a"
34577,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.103448276,"the, in, of, to, sars-cov-2, probably"
34578,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.103448276,"the, between, sars-cov-2, and, bat, is"
34579,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.103448276,"virus, the, was, sequence, that, sars-cov-2"
34580,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.103448276,"the, and, are, to, that, these"
34581,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.103448276,"that, to, host, with, sars-cov-2, the"
34582,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.103448276,"natural, of, and"
34583,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.103448276,"bat, origin, of"
34584,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.103448276,"of, natural, based, on, and, virus"
34585,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.103448276,"the, and, a"
34586,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.103448276,"the, and, viruses"
34587,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.103448276,"a, the, and"
34588,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.103448276,"that, sars-cov-2, was, the, virus, sequence"
34589,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.103448276,"that, sars-cov-2, the, covid-19, virus, genome"
34590,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.103448276,"was, and, to, sars-cov-2, the, genome"
34591,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.103448276,"and, sars-cov-2, ratg13, the, to, human"
34592,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.103448276,"the, of, sars-like"
34593,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.103448276,"of, to, most"
34594,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.103448276,"to, humans, can, be, of, and"
34595,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.103448276,"the, in, bats, of, that, a"
34596,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.103448276,"have, been, host, are, as, and"
34597,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.103448276,"to, the, with, a, coronavirus, is"
34598,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.103448276,"be, the, host, of, and, an"
34599,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.103448276,"to, the, in, and, that, a"
34600,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.103448276,"the, in, as"
34601,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.103448276,"to, the, bats, of, as, intermediate"
34602,COVID-19 is a zoonotic virus,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.103448276,"covid-19, is, zoonotic"
34603,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.103448276,"animal, to, a"
34604,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.103448276,"a, to, and, market, were, in"
34605,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.103448276,"is, sars-cov-2, a"
34606,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.103448276,"has, been, the, and, are, that"
34607,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","All human coronaviruses have animal origins, namely, natu- 

ral hosts",0.103448276,"all, coronaviruses, have"
34608,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.103448276,"and, bats, of"
34609,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",Bats are likely reservoir hosts for SARS-CoV-2,0.103448276,"sars-cov-2, bats, reservoir"
34610,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",Bats are likely reservoir hosts for SARS-CoV-2,0.103448276,"sars-cov-2, likely, bats"
34611,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",zoonotic origins of SARS-CoV-2 by natural evolution,0.103448276,"by, sars-cov-2, natural"
34612,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.103448276,"a, coronavirus, the, is, with, to"
34613,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.103448276,"and, coronaviruses, to"
34614,"bats are also important reservoir species for a great 

range of coronaviruses","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.103448276,"species, of, coronaviruses"
34615,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.103448276,"the, was, animals"
34616,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.103448276,"from, humans, the"
34617,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.103448276,"in, sars-cov-2, bat, that, the, is"
34618,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.103448276,"the, reservoirs, for"
34619,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.103448276,"that, the, of, bats, are, natural"
34620,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","civet cats and raccoon dogs  

are the intermediate hosts",0.103448276,"the, civet, hosts"
34621,"insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.103448276,"of, cats,, and"
34622,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.103448276,"sars-cov-2, to, animal"
34623,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.103448276,"the, transmitted, to"
34624,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.103448276,"animal, the, are"
34625,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","with the first case being linked to  

a seafood market",0.103448276,"to, with, the"
34626,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","with the first case being linked to  

a seafood market",0.103448276,"a, the, market"
34627,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.103448276,"yet, sars-cov-2, to, from, is, in"
34628,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.103448276,"even, though, the, of, sars-cov-2, is"
34629,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.103448276,"the, a, and"
34630,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.103448276,"the, by, a"
34631,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.103448276,"in, a, the"
34632,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.103448276,"zoonotic, in, and"
34633,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.103448276,"that, one, the"
34634,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.103448276,"are, have, been, as, and, host"
34635,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.103448276,"natural, of, a, to, that, as"
34636,"Bats are natural hosts of many of the known  

coronaviruses","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.103448276,"are, natural, the"
34637,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.103448276,"such, and, the, that, sars-cov-2, natural"
34638,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.103448276,"the, sars-cov-2, to, a, of, bat"
34639,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.103448276,"this, that, from, the, a, at, of, are, viruses"
34640,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.103448276,"hypothesis, in, the, of, that, sars-cov-2"
34641,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.103448276,"are, a, related, to, that, in"
34642,"with the first case being linked to  

a seafood market","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.103448276,"the, a, market"
34643,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.103448276,"in, the, closely, related, to, were"
34644,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.103448276,"was, at, market, in, that, the"
34645,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.103448276,"and, sars-cov-2, to, humans, on, in"
34646,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.103448276,"the, of, to, a, and, as"
34647,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor",0.103448276,"a, possible, sars-cov-2"
34648,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.103448276,"one, of, to, a, from, in"
34649,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.103448276,"the, that, animal, of, has, been, is, by, a"
34650,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.103448276,"sars-cov-2, to, from, in, is, yet"
34651,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.103448276,"to, sars-cov-2, was, in, from, an"
34652,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.103448276,"notably,, that, laboratory, was, and, to"
34653,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.103448276,"a, sars-cov-2, is"
34654,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.103448276,"to, a, as, from, in, tested, for, the, virus, live, were, of"
34655,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.103448276,"of, and, cats,"
34656,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.103448276,"to, the, coronavirus, and, that, a"
34657,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.103448276,"from, that, and"
34658,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.103448276,"of, and, coronaviruses, that, a, to"
34659,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.103448276,"and, a, to, that, coronaviruses, of"
34660,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.103448276,"and, from, can, which, that, in"
34661,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.103448276,"is, to, and"
34662,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.103448276,"from, to, human"
34663,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.103448276,"the, to, animal"
34664,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.103448276,"to, intermediate, animal"
34665,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.103448276,"the, possible, of"
34666,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.103448276,"of, the, a"
34667,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.103448276,"the, of, that, close, to, and"
34668,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.103448276,"of, the, in, a, to, that"
34669,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.103448276,"the, that, of, cases, market, in"
34670,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.103448276,"of, the, in, to, those, that"
34671,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.103448276,"from, a, to, the, which, that"
34672,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.103448276,"the, that, a, virus, coronavirus, covid-19"
34673,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.103448276,"of, pangolin, genome, and, which, to"
34674,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.103448276,"sars-cov-2, a, the"
34675,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.103448276,"the, sars-cov-2, a"
34676,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.103448276,"the, to, spike, with, of, and"
34677,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.103448276,"he, with, the, of, sars-cov-2, and"
34678,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.103448276,"the, sars-cov-2, coronavirus"
34679,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.103448276,"sars-cov-2, with, the"
34680,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.103448276,"the, to, a, of, available, that, virus, by, and"
34681,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.103448276,"is, the, and"
34682,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.103448276,"of, the, is"
34683,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.103448276,"sars-cov-2, of, which, to, have, that, an, and, the"
34684,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.103448276,"to, studies, on, the, and, is"
34685,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.103448276,"the, of, which, that, was, to"
34686,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.103448276,"on, and, to, of, which, the"
34687,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.103448276,"to, based, on, the, and, that"
34688,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.103448276,"the, and, a, in, are, to"
34689,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.103448276,"from, bats, to, a, in, the"
34690,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.103448276,"a, and, the, to, from, humans,"
34691,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.103448276,"the, and, a, in, to, are"
34692,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.103448276,"the, genetic, that, have, to, from"
34693,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.103448276,"a, sug-, gested, the, that, bats"
34694,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.103448276,"to, the, in, and, that, bats"
34695,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.103448276,"most, of, to"
34696,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.103448276,"was, the, and, to, which, is"
34697,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.103448276,"that, in, has"
34698,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.103448276,"is, and, to"
34699,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.103448276,"the, animal, to"
34700,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.103448276,"the, origin, and"
34701,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.103448276,"in, the, and, to, that, is"
34702,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.103448276,"and, in, to, that, the, is"
34703,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.103448276,"bat, the, and"
34704,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.103448276,"studies, on, the, and, is, to"
34705,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.103448276,"the, sars-like, are"
34706,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.103448276,"the, sars-like, of"
34707,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.103448276,"the, from, market"
34708,Bats are likely reservoir hosts for SARS-CoV-2,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.103448276,"bats, reservoir, sars-cov-2"
34709,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.103448276,"analysis, bats, the, to, be, could"
34710,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.103448276,"was, first, in"
34711,"civet cats and raccoon dogs  

are the intermediate hosts","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.103448276,"civet, the, hosts"
34712,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.103448276,"sug-, gested, that, the, bats, a"
34713,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.103448276,"the, of, coronavirus, sars-like, bat, be"
34714,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.103448276,"with, the, of, bats, a, sars-like"
34715,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.103448276,"of, viruses, bat, a, possible, the"
34716,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.103448276,"to, is, the, which, and, was"
34717,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.103448276,"of, be, the, coronavirus, sars-like, bat"
34718,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.103448276,"to, and, with, the, spike, of"
34719,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.103448276,"analysis, to, bats, could, be, the"
34720,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.103448276,"the, bats, to, as, of, and"
34721,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.103448276,"analysis, the, bats, and, to, of"
34722,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.103448276,"spillover, intermediate, to"
34723,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.103448276,"he, and, with, the, of, sars-cov-2"
34724,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.103448276,"the, analysis, et, that, sars-cov-2, and"
34725,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.103448276,"the, as, of, sars-cov-2, bat, and"
34726,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","Coronaviruses are naturally hosted and developmentally 

formed by bats.",0.103448276,"are, by, coronaviruses"
34727,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.103448276,"the, that, from"
34728,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.103448276,"the, that, bat"
34729,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.103448276,"the, of, a, in, viruses, are"
34730,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.103448276,"of, from, a, in, pangolin, the"
34731,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.103448276,"the, of, viruses, spike, in, a"
34732,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.103448276,"the, pangolin, as"
34733,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.103448276,"bats, the, most"
34734,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.103448276,"covid-19, the, in"
34735,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.103448276,"to, a, animal"
34736,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.103448276,"zoonotic, to, that"
34737,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.103448276,"a, that, to"
34738,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.103448276,"coronaviruses, in, of"
34739,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.103448276,"in, coronaviruses, to"
34740,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.103448276,"in, bat, populations"
34741,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.103448276,"found, the, in"
34742,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.103448276,"to, the, have, been, in, and"
34743,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.103448276,"the, that, animal"
34744,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.103448276,"humans, animal, host."
34745,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.103448276,"that, of, coronavirus"
34746,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.103448276,"the, significant, in, of, 2020, and, with, showed, covid-19"
34747,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",COVID-19 is a zoonotic virus,0.103448276,"is, zoonotic, covid-19"
34748,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.103448276,"virus, to, genome"
34749,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.103448276,"to, be, from"
34750,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.103448276,"that, to, zoonotic"
34751,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.103448276,"to, the, of, bats, as, intermediate"
34752,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.103448276,"and, human, a, natural, of, the"
34753,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.103448276,"to, pangolin, and, a, the, of"
34754,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.103448276,"sars-cov-2, of, the, similar, to, analysis"
34755,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.103448276,"that, the, of, close, to, and"
34756,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.103448276,"to, the, of, and, that, covid-19"
34757,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","no modifications were  

recorded for nonstructural proteins NSP7, NSP13  

and the structured and accessory proteins p6 and 8b.",0.103448276,"were, and, the"
34758,zoonotic origins of SARS-CoV-2 by natural evolution,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.103448276,"sars-cov-2, by, natural"
34759,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.103448276,"that, the, sars-cov-2, et, and, analysis"
34760,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.103448276,"animal, sars-cov-2, to"
34761,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.103448276,"zoonotic, in, to"
34762,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.103448276,"is, between, and, bat, et, that"
34763,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.103448276,"the, analyses, of, and, s, genomes"
34764,Wet Market animals maintained in poor conditions,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.103448276,"market, animals, in"
34765,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","the close relation  

between SARS coronavirus and 2019-nCoV",0.103448276,"the, and, sars"
34766,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.103448276,"that, were, in, china, market, a, at, and, on"
34767,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.103448276,"and, in, the, of, sars-cov-2, has"
34768,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.103448276,"a, in, that"
34769,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.103448276,"a, sars-cov-2, in"
34770,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.103448276,"in, that, sars-cov-2"
34771,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.103448276,"the, from, that, a, pangolin, coronavirus"
34772,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.103448276,"of, these, a, sequence, from, in"
34773,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.103448276,"coronaviruses, a, that, of, to, and"
34774,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.103448276,"of, the, are, in, viruses, a"
34775,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.103448276,"analyses, of, genomes, the, and, s"
34776,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.103448276,"the, most, bats"
34777,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.103448276,"the, to, are"
34778,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Bats are natural hosts of many of the known  

coronaviruses",0.103448276,"natural, are, the"
34779,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Bats are natural hosts of many of the known  

coronaviruses",0.103448276,"the, coronaviruses, are"
34780,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.103448276,"that, in, which, can, and, from"
34781,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.103448276,"et, that, between, and, bat, is"
34782,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.103448276,"to, bat, is, that, bats, as"
34783,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.103448276,"the, of, that, which, was, to"
34784,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.103448276,"considered, intermediate, the"
34785,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.103448276,"from, a, coronavirus, with, sars-cov-2, the"
34786,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.103448276,"a, genome, to"
34787,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.103448276,"that, a, the, was, with, of, in, at, to"
34788,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.103448276,"of, with, a, to, the, in"
34789,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.103448276,"was, that, to"
34790,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.103448276,"coronaviruses, to, and"
34791,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.103448276,"suggest, that, the"
34792,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.103448276,"of, are, the"
34793,"preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.103448276,"data, that, of"
34794,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.103448276,"scientific, that, sars-cov-2"
34795,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.103448276,"the, of, cov"
34796,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.103448276,"in, the, a, was, from, to"
34797,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.103448276,"was, an, sars-cov-2, to, from, in"
34798,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.103448276,"in, the, of, a, isolated, from"
34799,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.103448276,"the, batcov, in"
34800,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.103448276,"the, in, was"
34801,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.103448276,"another, bat, the"
34802,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.103448276,"been, have, sars-cov-2"
34803,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.103448276,"that, the, animal"
34804,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.103448276,"animal, at, the"
34805,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.103448276,"sars-cov-2, and, a"
34806,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.103448276,"of, the, viruses"
34807,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.103448276,"the, and, origin"
34808,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.103448276,"from, a, malayan, and, sars-cov-2, the"
34809,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.103448276,"and, pangolins, sars-cov-2"
34810,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.103448276,"and, sars-cov-2, ratg13, the, between, origin"
34811,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.103448276,"the, of, hypothesis, that, sars-cov-2, in"
34812,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.103448276,"animals, transmitted, to"
34813,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.103448276,"the, a, was"
34814,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.103448276,"by, coronavirus, the"
34815,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.103448276,"the, a, laboratory"
34816,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.103448276,"are, in, virus"
34817,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.103448276,"zoonotic, are, including"
34818,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.103448276,"the, a, as, to, of, and"
34819,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.103448276,"in, bat, and"
34820,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.103448276,"to, that, bats, hosts, for, are"
34821,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.103448276,"a, of, the, with, sars-like, bats"
34822,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.103448276,"sars-cov-, the, genome, and, bats, for"
34823,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.103448276,"a, sars-cov-2, similarity"
34824,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.103448276,"sars-cov-2, a, in"
34825,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.103448276,"the, considered, intermediate"
34826,The COVID-19 most likely developed from bat origin coronaviruses,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.103448276,"the, most, bat"
34827,The COVID-19 most likely developed from bat origin coronaviruses,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.103448276,"the, covid-19, coronaviruses"
34828,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.103448276,"in, the, to, that, sars-cov-2, is"
34829,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.103448276,"that, sars-cov-2, to, with, the, host"
34830,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.103448276,"the, from, bats, to, a, in"
34831,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.103448276,"of, the, in, from, a, pangolin"
34832,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.103448276,"a, from, the, coronavirus, with, sars-cov-2"
34833,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.103448276,"the, that, host, of, is, a"
34834,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.103448276,"analysis, that, the, of, a, coronavirus"
34835,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.103448276,"the, from, analysis, that, to, sars-"
34836,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.103448276,"analysis, of, that, is, to, the"
34837,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.103448276,"a, study, of, from, in, sars-cov-2"
34838,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.103448276,"has, that, in"
34839,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.103448276,"that, strain, sars-cov-2"
34840,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.103448276,"the, is, similar"
34841,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.103448276,"sars-cov-2, that, the"
34842,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.103448276,"from, the, market"
34843,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.103448276,"the, to, from"
34844,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.103448276,"the, from, virus"
34845,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.103448276,"to, the, virus"
34846,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.103448276,"nucleotide, identity, to"
34847,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.103448276,"that, the, animal, by, a, of, is, has, been"
34848,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.103448276,"that, of, host, is, a, the"
34849,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.103448276,"a, by, that, the, is, of"
34850,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.103448276,"the, has, a, that, not, of"
34851,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.103448276,"in, the, found"
34852,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.103448276,"batcov, in, the"
34853,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.103448276,"has, sars-cov-2, in"
34854,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.103448276,"the, to, as, and, in, has, et, al., also"
34855,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","bats are also important reservoir species for a great 

range of coronaviruses",0.103448276,"are, also, of"
34856,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","bats are also important reservoir species for a great 

range of coronaviruses",0.103448276,"reservoir, of, a"
34857,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.103448276,"the, amino, acid, sars-cov-2, which, of"
34858,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.103448276,"that, sars-cov-2, natural, and, such, the"
34859,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.103448276,"the, of, sars-cov-2, or, a, in"
34860,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.103448276,"animal, a, and, in, the, that"
34861,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.103448276,"the, of, that, sars-cov-2, a, with"
34862,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.103448276,"sars-cov-2, humans, in, and, to, on"
34863,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.103448276,"the, that, sars-cov-2, to, with, than"
34864,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.103448276,"the, and, are, that, these, to"
34865,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.103448276,"has, been, that, and, are, the"
34866,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.103448276,"the, sars-cov-2, and, to, a, in"
34867,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.103448276,"of, the, it, is, to, sars-cov-2"
34868,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.103448276,"it, by, and, to, sars-cov-2, the"
34869,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.103448276,"some, of, and, the, may, between"
34870,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.103448276,"very, from, to"
34871,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.103448276,"to, spillover, intermediate"
34872,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.103448276,"to, the, zoonotic"
34873,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.103448276,"the, a, was, that, to, and"
34874,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.103448276,"that, was, notably,, to, and, laboratory"
34875,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.103448276,"the, animal, at"
34876,"The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.103448276,"the, were, several"
34877,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.103448276,"banal, series, in"
34878,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.103448276,"sars-cov-2, with, to"
34879,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.103448276,"and, the, it, that, of, sars-cov-2, in, from, a"
34880,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.103448276,"not, do, of, the, reservoir, including"
34881,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.103448276,"the, host, for"
34882,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.103448276,"virus, genome, the, covid-19, that, sars-cov-2"
34883,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.103448276,"the, of, from, a, sars-cov-2, or"
34884,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.103448276,"sars-cov-2, in, a, of, the, or"
34885,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.103448276,"the, of, bats, and, are, more"
34886,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.103448276,"of, the, which"
34887,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.103448276,"the, of, viruses, sars, bats, as, and, progenitor, for"
34888,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.103448276,"bats, as, the, to, of, and"
34889,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.103448276,"bat, the, of, as, sars-cov-2, and"
34890,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.103448276,"to, the, in, and, that, china"
34891,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.103448276,"in, the, other"
34892,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.103448276,"an, in, of"
34893,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.103448276,"a, of, the, possible, bat, viruses"
34894,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.103448276,"are, viruses, the, in, and, possible"
34895,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.103448276,"that, the, of, in, to, a"
34896,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.103448276,"viruses, closely, to, a, the, same"
34897,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.103448276,"bat, to, the, viruses, that, in"
34898,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.103448276,"genome, the, was, to, and, sars-cov-2"
34899,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.103448276,"the, sars-cov-2, to, it, and, by"
34900,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.103448276,"the, was, to, it, in, with"
34901,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.103448276,"of, the, with, to, ace2, rbd"
34902,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","This suggests that the BANAL series may be able to directly infect  

humans.",0.103448276,"that, the, this"
34903,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.103448276,"than, to, in"
34904,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.103448276,"the, more, of"
34905,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.103448276,"the, of, viruses"
34906,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.103448276,"the, viruses, of"
34907,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.103448276,"a, of, viruses"
34908,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.103448276,"the, same, closely, viruses, a, to"
34909,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.103448276,"as, in, bats"
34910,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.103448276,"and, in, bats"
34911,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.103448276,"in, was, first"
34912,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.103448276,"and, was, in"
34913,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.103448276,"in, most, to"
34914,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.103448276,"several, were, the"
34915,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.103448276,"a, in, the, with, that, was, to, of, at"
34916,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.103448276,"virus, more, than, identical, to, in"
34917,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.103448276,"the, to, in, a, for, of, as, reservoir, horseshoe, sars, that, bats, were, and, civets,"
34918,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.103448276,"bats, as, the, for, progenitor, viruses, of, sars, and"
34919,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.103448276,"in, a, of, to, the, virus, from, were, live, for, as, tested"
34920,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.103448276,"had, from, as, and, multiple, to, for, by, the, of, in, a"
34921,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.103448276,"a, viruses, are, at, that, the, of, from, this"
34922,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.103448276,"that, and, in, were, at, a, market, china, on"
34923,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.103448276,"a, of, available, to, that, by, the, and, virus"
34924,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.103448276,"to, the, sars, bats, were, as, for, and, a, reservoir, in, of, horseshoe, that, civets,"
34925,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.103448276,"that, bats, are, the, reservoir, for, a, of, and"
34926,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.103448276,"of, the, covid-19, in, with, and, 2020, showed, significant"
34927,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.103448276,"were, to, a, and, market, in"
34928,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.103448276,"a, in, the, with, to, of"
34929,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.103448276,"on, the, of, and, which, to"
34930,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.103448276,"in, a, animal, and, that, the"
34931,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.103448276,"sequences, in, the, of, these, and"
34932,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.103448276,"in, the, of, is, at, that"
34933,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.103448276,"sars-cov-2, from, a, of, in, the, and, it, that"
34934,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.103448276,"in, the, of, between, and, market"
34935,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","expended to make the simple point 

that COVID-19 had a natural origin.",0.103448276,"that, a, to"
34936,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","expended to make the simple point 

that COVID-19 had a natural origin.",0.103448276,"that, natural, the"
34937,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.",0.103448276,"zoonotic, the, and"
34938,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.103448276,"the, that, ace2, a, this, evidence"
34939,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.103448276,"the, virus, from"
34940,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","atural  

selection in an animal host before zoonotic  

transfer;",0.103448276,"an, animal, in"
34941,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","atural  

selection in an animal host before zoonotic  

transfer;",0.103448276,"in, an, host"
34942,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.103448276,"is, bat, as, to, that, bats"
34943,The COVID-19 most likely developed from bat origin coronaviruses,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.103448276,"the, likely, bat"
34944,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.103448276,"to, the, which, may, from, human"
34945,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.103448276,"the, a, which, to, that, from"
34946,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.103448276,"that, may, a, to, ratg13,, the"
34947,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.103448276,"the, that, all, sars-cov-2, to, pangolin"
34948,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.103448276,"the, site, and, which, a, of"
34949,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.103448276,"the, a, of, that, by, and"
34950,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.103448276,"the, a, of, that, jumped, r."
34951,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.103448276,"the, sars-cov-2, to, of, in, probably"
34952,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.103448276,"sars-cov-2, a, the, of, or, from"
34953,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.103448276,"and, in, the, of, sars-cov-2, is"
34954,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.103448276,"the, genome, of, bat, that, a"
34955,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.103448276,"that, of, a, coronavirus, analysis, the"
34956,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.103448276,"a, genome, that, the, closely, of"
34957,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.103448276,"the, virus, covid-19, a, that, coronavirus"
34958,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.103448276,"the, ace2, a, that, this, evidence"
34959,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.103448276,"of, the, spike, in, viruses, a"
34960,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.103448276,"to, the, in, bats, of, and"
34961,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.103448276,"that, sars-, from, to, analysis, the"
34962,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.103448276,"and, the, to, from, animals, humans,"
34963,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",The COVID-19 most likely developed from bat origin coronaviruses,0.103448276,"the, coronaviruses, covid-19"
34964,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",The COVID-19 most likely developed from bat origin coronaviruses,0.103448276,"the, bat, likely"
34965,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.103448276,"analysis, bats, the, to, of, and"
34966,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.103448276,"of, viruses, a"
34967,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.103448276,"and, zoonotic, in"
34968,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.103448276,"to, in, zoonotic"
34969,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.103448276,"transmitted, to, animals"
34970,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.103448276,"be, that, to"
34971,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",Bats are hosts of many coronaviruses,0.103448276,"are, coronaviruses, many"
34972,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.103448276,"intermediate, animal, to"
34973,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.103448276,"most, to, in"
34974,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.103448276,"emerged, in, to"
34975,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.103448276,"in, to, the, covid-19, is, market"
34976,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.103448276,"the, to, is"
34977,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.103448276,"in, to, be"
34978,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.103448276,"is, the, to"
34979,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.103448276,"which, have, been"
34980,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.103448276,"the, of, which"
34981,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.103448276,"that, of, to, is, analysis, the"
34982,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.103448276,"the, a, coronavirus, that, and, to"
34983,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.103448276,"the, of, to, suggesting, that, bats"
34984,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.103448276,"the, guangdong, wildlife, pangolins, march, and, in, all, of, that, least, sars-cov-2-like"
34985,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.103448276,"the, in, that, bats, are, for"
34986,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.103448276,"that, the, between, and, guangdong, viruses"
34987,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.103448276,"it, was, in, with, to, the"
34988,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.103448276,"the, one, that"
34989,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.103448276,"the, bat, sars-"
34990,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.103448276,"the, of, may, and, between, some"
34991,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.103448276,"of, can, be, to, humans, and"
34992,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.103448276,"the, humans, from"
34993,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.103448276,"from, the, to"
34994,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.103448276,"the, from, be"
34995,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.103448276,"of, a, higher, as, and, diversity"
34996,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.103448276,"virus, are, in"
34997,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.103448276,"et, al., in, to, the, has, also, and, as"
34998,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.103448276,"the, was, a"
34999,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.103448276,"in, the, and, of, between, market"
35000,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.103448276,"in, the, wildlife"
35001,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.103448276,"of, and, the, from, in, pangolins"
35002,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.103448276,"that, the, of, all, and, sars-cov-2-like, in, least, guangdong, march, pangolins, wildlife"
35003,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.103448276,"the, bats, and, pangolins, may, have"
35004,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.",0.103448276,"of, data, that"
35005,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.103448276,"a, the, of, is, and, that"
35006,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.103448276,"and, the, from, to, humans,, a"
35007,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.103448276,"the, reservoir, of, including, do, not"
35008,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.103448276,"the, from, to, humans,, and, animals"
35009,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.103448276,"r., that, a, of, jumped, the"
35010,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.103448276,"the, sars-cov-2, a, from, malayan, and"
35011,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.103448276,"and, from, in, to, be, the, coronavirus, hosts, sars-cov-2"
35012,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.103448276,"is, the, in"
35013,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.103448276,"and, in, the, is, bats, very"
35014,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.103448276,"the, zoonotic, to"
35015,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","ARS-CoV-2 is a 

natural virus, not a lab-created one.",0.103448276,"a, natural, is"
35016,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.103448276,"the, animal, are"
35017,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.103448276,"the, coronavirus, by"
35018,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.103448276,"the, other, in"
35019,"bats are also important reservoir species for a great 

range of coronaviruses","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.103448276,"reservoir, a, of"
35020,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.103448276,"had, to, a, as, from, in, multiple, for, the, by, of, and"
35021,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.103448276,"the, by, of, in, and, that, this, a, laboratory"
35022,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.103448276,"the, was, sars-cov-2"
35023,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.103448276,"suggested, sars-cov-2, animal"
35024,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.103448276,"and, a, the, natural, of, human"
35025,"ARS-CoV-2 is a 

natural virus, not a lab-created one.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.103448276,"is, a, natural"
35026,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.103448276,"the, sars-cov-2, even, though, of, is"
35027,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.103448276,"a, diversity, of, and, as, higher"
35028,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.103448276,"the, and, has, a, ability, of"
35029,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.103448276,"has, sars-cov-2, and, the, of, in"
35030,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.103448276,"to, nucleotide, identity"
35031,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.103448276,"that, from, and"
35032,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.103448276,"that, was, to"
35033,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.103448276,"that, the, from"
35034,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.103448276,"from, be, the"
35035,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.103448276,"the, that, as"
35036,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.103448276,"to, sars-cov-2, its"
35037,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.103448276,"the, a, coronavirus, from, pangolin, that"
35038,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.103448276,"pangolin, to, sars-cov-2, the, all, that"
35039,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.103448276,"sars-cov-2, pangolins, and"
35040,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.103448276,"and, for, sars-cov-2"
35041,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.103448276,"and, that, bats, are, hosts, sars-cov-2"
35042,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.103448276,"were, in, closely, related, to, the"
35043,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.103448276,"the, that, of, is, by, a"
35044,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.103448276,"that, the, of, genome, closely, a"
35045,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.103448276,"a, study, of, from, in, china"
35046,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.103448276,"from, in, one, of, a, to"
35047,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.103448276,"sequence, in, of, a, from, these"
35048,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.103448276,"2, human, and, viruses, of, the"
35049,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.103448276,"the, to, ratg13, and, human, sars-cov-2"
35050,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.103448276,"a, in, the, sars-cov-2, human, for"
35051,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.103448276,"genome, of, which, to, pangolin, and"
35052,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.103448276,"ratg13,, a, to, the, that, may"
35053,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.103448276,"and, this, by, the, of, that, in, a, laboratory"
35054,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.103448276,"the, sars-cov-2, and, a, of, in"
35055,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.103448276,"sars-cov-2, bat, ratg13"
35056,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.103448276,"sars-cov-2, shown, to"
35057,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.103448276,"based, on, the, and, that, to"
35058,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.103448276,"that, the, in, bats, and, to"
35059,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.103448276,"the, bats, for, sars-cov-, genome, and"
35060,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.103448276,"and, viruses, are, possible, in, the"
35061,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.103448276,"to, and, possible, that, viruses, in"
35062,Bats are likely reservoir hosts for SARS-CoV-2,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.103448276,"bats, likely, sars-cov-2"
35063,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.103448276,"novel, that, the, of, sars-cov-2, and"
35064,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.103448276,"that, the, bat, in, viruses, to"
35065,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.103448276,"the, origin, sars-cov-2, between, and, ratg13"
35066,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.103448276,"between, and, that, in, the, sars-cov-2"
35067,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.103448276,"bat, of, origin"
35068,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.103448276,"cov, the, of"
35069,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.103448276,"the, sars-, bat"
35070,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.103448276,"that, bats, are, the, in, for"
35071,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.103448276,"more, the, of"
35072,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.103448276,"the, between, sars-cov-2, and, is, bat"
35073,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.103448276,"that, the, and, viruses, guangdong, between"
35074,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.103448276,"the, are, more, of, bats, and"
35075,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.103448276,"bats, and, pangolins, may, have, the"
35076,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.103448276,"the, of, and, sequences, these, in"
35077,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.103448276,"and, a, to, the, of, pangolin"
35078,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.103448276,"the, a, of, that, to, and"
35079,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.103448276,"sars-cov-2, a, of, that, the, with"
35080,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.103448276,"that, sars-cov-2, to, than, the, with"
35081,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.103448276,"sars-cov-2, and, to"
35082,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.103448276,"to, sars-cov, and"
35083,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.103448276,"the, to, with"
35084,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.103448276,"with, to, sars-cov-2"
35085,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.103448276,"is, and, the"
35086,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.103448276,"the, sars-cov-2, pangolin-cov"
35087,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.103448276,"from, the, and"
35088,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.103448276,"in, and, sars-cov-2, that, the, between"
35089,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.103448276,"the, are, a, for, of, reservoir, that, bats, and"
35090,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.103448276,"are, to, the"
35091,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.103448276,"to, the, in"
35092,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.103448276,"sars-cov-2, the, in"
35093,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.103448276,"the, of, rbd, to, that, sars-cov-2"
35094,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.103448276,"to, the, bats, of, suggesting, that"
35095,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.103448276,"of, at, the, in, to, that"
35096,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.103448276,"the, as, pangolin"
35097,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.103448276,"in, the, as"
35098,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.103448276,"that, the, bat"
35099,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.103448276,"the, for, in"
35100,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.103448276,"from, to, be"
35101,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.103448276,"the, of, and, be, an, host"
35102,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.103448276,"another, the, bat"
35103,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.103448276,"a, the, sars-cov-2"
35104,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.103448276,"a, that, the, or, from, in"
35105,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.103448276,"a, sars-cov-2, in, the, for, human"
35106,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.103448276,"the, of, and, is, to, an"
35107,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.103448276,"study, of, from, a, in, sars-cov-2"
35108,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.103448276,"a, study, from, in, china, of"
35109,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.103448276,"region, a, in, bat, coronaviruses, of"
35110,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.103448276,"are, zoonotic, including"
35111,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.103448276,"to, that, as, a, of, natural"
35112,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.103448276,"in, a, related, that, are, to"
35113,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.103448276,"of, to, the, those, in, that"
35114,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.103448276,"of, the, that, bats, are, natural"
35115,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.103448276,"coronavirus, from, and, sars-cov-2, hosts, to, be, in, the"
35116,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.103448276,"the, in, bats, is, and, very"
35117,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.103448276,"that, bats, and, are, hosts, sars-cov-2"
35118,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.103448276,"the, that, of, has, not, a"
35119,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.103448276,"the, of, has, a, ability, and"
35120,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.103448276,"a, of, bat, region, in, coronaviruses"
35121,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.103448276,"viruses, to, in, and, that, possible"
35122,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.103448276,"of, sars-, cov-2, to, is, the"
35123,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.103448276,"the, is, closely, related, to, of"
35124,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.103448276,"based, on, virus, and, natural, of"
35125,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.103448276,"of, the, analysis, sars-cov-2, similar, to"
35126,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.103448276,"the, rbd, of, with, to, ace2"
35127,"An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.103448276,"of, coronaviruses, bat"
35128,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.103174603,"for, and, together, with, to, the, market, in, of, on, a, was, animal"
35129,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.103174603,"the, to, in, a, for, of, together, with, on, was, animal, and, market"
35130,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.103092784,"that, from, bats, in, the, a, or, and, large, of"
35131,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.103092784,"its, in, the, of, that, sars-cov-2, was, closely, related, to"
35132,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.103092784,"to, zoonotic, they, and, a, of, species, that, coronaviruses, have"
35133,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.103092784,"early, cases, with, the, huanan, of, covid-19, in, by, market"
35134,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.103092784,"at, infected, to, a, from, in, the, virus, china, and"
35135,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.103092784,"the, that, was, to, closely, related, in, its, of, sars-cov-2"
35136,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.103092784,"and, the, of, also, as, a, with, that, in, for"
35137,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.103092784,"bat, a, in, the, by, southern, suggesting, of, and, species"
35138,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.103092784,"also, in, a, of, and, that, the, with, as, for"
35139,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.103092784,"coronaviruses, have, a, zoonotic, that, they, species, of, to, and"
35140,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.103092784,"the, virus, in, and, to, from, infected, at, a, china"
35141,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.103092784,"of, and, southern, by, bat, suggesting, a, species, in, the"
35142,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.103092784,"a, large, of, and, that, the, or, from, in, bats"
35143,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.103092784,"of, covid-19, cases, in, the, huanan, market, with, by, early"
35144,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.102941176,"that, bats, the, of, and, in, pangolins"
35145,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.102941176,"a, sars-cov-2, and, are, in, which, viruses"
35146,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.102941176,"in, and, to, sars-cov-2, bat, pangolin, are"
35147,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.102941176,"that, of, from, to, sars-cov-2, sequences, the"
35148,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.102941176,"some, of, and, the, in, between, bat"
35149,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.102941176,"the, and, to, that, of, bat, are"
35150,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.102941176,"a, the, of, it, found, that, is"
35151,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.102941176,"the, of, is, found, a, to, that"
35152,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.102941176,"the, of, that, a, sequence, found, to"
35153,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.102941176,"the, it, that, was, of, sars-cov-2, a"
35154,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.102941176,"the, of, that, a, in, human, as"
35155,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.102941176,"its, as, the, of, that, in, a"
35156,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.102941176,"the, to, appear, that, in, with, of"
35157,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.102941176,"a, the, and, in, virus, that, is"
35158,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.102941176,"the, is, in, a, virus, to, that"
35159,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.102941176,"in, a, and, that, the, with, for"
35160,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.102941176,"evidence, in, the, of, to, from, through"
35161,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.102941176,"a, that, by, had, the, who, virus"
35162,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.102941176,"spread, such, and, the, that, sars-cov-2, have"
35163,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.102941176,"the, and, that, of, bat, ratg13, they"
35164,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.102941176,"and, sars-cov-2, are, in, a, which, viruses"
35165,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.102941176,"the, that, in, a, two, from, humans"
35166,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.102941176,"the, of, a, in, and, market, at"
35167,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.102941176,"coronavirus, from, and, other, hosts, in, the"
35168,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.102941176,"and, from, in, were, to, of, sars-cov-2"
35169,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.102941176,"of, and, a, to, zoonotic, in, as"
35170,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.102941176,"a, the, of, sars-cov-2, and, but, an"
35171,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.102941176,"sars-cov-2, in, a, of, animal, and, the"
35172,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.102941176,"that, may, sars-cov-2, to, humans, the, in"
35173,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.102941176,"in, the, early, to, that, may, have"
35174,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.102941176,"that, was, sars-cov-2, and, is, to, an"
35175,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.102941176,"it, in, unlike, and, are, to, that"
35176,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.102941176,"there, no, at, the, virus, as, of"
35177,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.102941176,"the, virus, and, be, because, of, to"
35178,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.102941176,"a, the, from, that, two, in, humans"
35179,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.102941176,"the, virus, was, as, a, that, to"
35180,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.102941176,"the, virus, have, from, in, market, to"
35181,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.102941176,"in, the, same, of, a, to, as, found, were, that, likely, from, this, first"
35182,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.102941176,"the, of, to, that, was, transmitted, from"
35183,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.102941176,"found, that, the, of, is, a, it"
35184,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.102941176,"a, is, the, that, in, virus, and"
35185,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.102941176,"the, but, an, and, a, of, sars-cov-2"
35186,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.102941176,"strong, to, sars-cov-2, the, that, is, of"
35187,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.102941176,"the, that, of, “the, sars-cov-2, is, an"
35188,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.102941176,"evidence, to, that, the, of, and, sars-cov-2"
35189,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.102941176,"of, the, have, in, that, was, by"
35190,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.102941176,"a, to, the, virus, that, was, as"
35191,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.102941176,"as, and, to, was, the, that, a"
35192,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.102941176,"the, of, from, infected, humans, to, and"
35193,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.102941176,"to, sars-cov-2, of, sequences, the, and, that"
35194,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.102941176,"on, the, by, of, and, virus,, that"
35195,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.102941176,"in, bats, which, are, to, of, and"
35196,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.102941176,"as, the, of, at, there, virus, no"
35197,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.102941176,"the, of, and, to, because, be, virus"
35198,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.102941176,"that, the, to, may, be, of, and"
35199,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.102941176,"samples, at, the, be, that, for, from"
35200,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.102941176,"the, of, bat, that, a, however,, viruses"
35201,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.102941176,"that, of, bats, a, coronavirus, with, the"
35202,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.102941176,"a, that, the, group, of, sars-like, bats"
35203,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.102941176,"the, a, that, bat, not, of, but"
35204,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.102941176,"sars-cov-2, of, the, and, to, virus, genetic"
35205,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.102941176,"in, to, have, the, virus, from, market"
35206,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.102941176,"and, the, then, or, into, in, from"
35207,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.102941176,"in, the, of, and, with, pneumonia, subsequently"
35208,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.102941176,"the, of, and, that, virus, sars, to"
35209,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.102941176,"a, of, the, however,, bat, viruses, that"
35210,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.102941176,"et, that, may, a, to, and, sars-cov-2"
35211,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.102941176,"and, pneumonia, with, the, subsequently, in, of"
35212,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.102941176,"in, similar, at, with, the, of, on"
35213,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.102941176,"had, before, to, the, of, that, sars-cov-2"
35214,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.102941176,"sars-cov-2, the, of, that, to, sequences, from"
35215,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.102941176,"a, of, the, coronavirus, with, that, bats"
35216,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.102941176,"is, an, a, the, in, from, pangolin"
35217,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.102941176,"to, sars-cov-2, from, in, the, and, has"
35218,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.102941176,"sars-cov-2, be, the, with, furin, cleavage, in"
35219,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.102941176,"et, that, of, to, and, the, sars-cov-2"
35220,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.102941176,"in, the, a, that, and, with, for"
35221,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.102941176,"in, the, animal, and, a, of, sars-cov-2"
35222,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.102941176,"a, for, the, as, of, and, with"
35223,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.102941176,"sars-cov-2, in, the, that, for, ace2, of"
35224,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.102941176,"in, humans, the, that, sars-cov-2, may, to"
35225,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.102941176,"early, in, the, that, may, have, to"
35226,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.102941176,"are, that, it, to, and, unlike, in"
35227,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.102941176,"the, has, been, are, that, have, to"
35228,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.102941176,"to, that, the, and, may, have, are"
35229,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.102941176,"in, the, of, were, to, huanan, market"
35230,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.102941176,"the, of, and, sequences, that, sars-cov-2, to"
35231,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.102941176,"in, to, the, sars-cov-2, has, from, and"
35232,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.102941176,"to, a, furin, cleavage, site, in, and"
35233,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.102941176,"to, and, of, it, that, in, southeast"
35234,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.102941176,"the, by, of, in, and, this, a"
35235,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.102941176,"found, that, the, of, is, to, a"
35236,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.102941176,"a, is, the, to, that, in, virus"
35237,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.102941176,"the, related, to, for, a, is, likely"
35238,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.102941176,"to, a, in, and, furin, cleavage, site"
35239,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.102941176,"the, of, as, virus, to, closely, related"
35240,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.102941176,"to, from, a, of, the, and, with"
35241,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.102941176,"who, a, that, the, virus, had, by"
35242,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.102941176,"of, virus, revealed, that, to, the, for"
35243,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.102941176,"found, that, the, sequence, of, to, a"
35244,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.102941176,"and, that, the, virus, to, sars, of"
35245,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.102941176,"the, of, to, likely, that, as, for"
35246,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.102941176,"that, from, a, to, in, intermediate, host"
35247,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.102941176,"the, of, closely, related, virus, to, as"
35248,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.102941176,"that, the, at, of, virus, and, to"
35249,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.102941176,"in, a, of, to, the, likely, that, first, this, from, were, found, same, as"
35250,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.102941176,"a, in, shows, the, to, of, were"
35251,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.102941176,"was, that, the, of, sars-cov-2, a, it"
35252,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.102941176,"the, samples, from, at, for, that, be"
35253,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.102941176,"the, into, from, in, or, and, then"
35254,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.102941176,"a, that, the, sars-cov-2, in, its, samples"
35255,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.102941176,"the, of, it, likely, that, for, its"
35256,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.102941176,"the, to, from, through, evidence, in, of"
35257,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.102941176,"of, the, in, to, were, huanan, market"
35258,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.102941176,"samples, the, that, its, sars-cov-2, in, a"
35259,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.102941176,"for, the, of, that, likely, as, to"
35260,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.102941176,"the, it, likely, that, its, for, of"
35261,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.102941176,"that, the, of, sars-cov-2, is, strong, to"
35262,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.102941176,"sars-cov-2, ace2, in, of, that, the, for"
35263,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.102941176,"viruses, to, the, in, and, that, could"
35264,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.102941176,"that, the, of, in, was, have, by"
35265,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.102941176,"of, revealed, that, for, the, to, virus"
35266,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.102941176,"of, and, that, the, in, bats, pangolins"
35267,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.102941176,"of, and, the, in, bats, viruses, between"
35268,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.102941176,"and, of, between, in, the, for, viruses"
35269,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.102941176,"the, of, appear, in, with, that, to"
35270,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.102941176,"the, between, and, some, of, in, bat"
35271,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.102941176,"bats, the, of, and, viruses, in, between"
35272,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.102941176,"are, to, on, and, bats, be, possible"
35273,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.102941176,"a, and, of, at, the, market, in"
35274,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.102941176,"of, was, to, which, the, in, animals"
35275,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.102941176,"on, in, the, of, with, similar, at"
35276,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.102941176,"the, related, is, for, likely, a, to"
35277,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.102941176,"other, coronavirus, and, in, the, from, hosts"
35278,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.102941176,"has, been, the, are, to, that, have"
35279,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.102941176,"intermediate, host, that, from, a, in, to"
35280,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.102941176,"in, the, of, that, its, as, a"
35281,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.102941176,"that, sars-cov-2, have, and, such, spread, the"
35282,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.102941176,"the, was, as, a, that, and, to"
35283,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.102941176,"that, the, of, had, to, sars-cov-2, before"
35284,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.102941176,"that, the, of, sars-cov-2, “the, is, an"
35285,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.102941176,"from, an, is, a, in, pangolin, the"
35286,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.102941176,"are, in, to, of, which, bats, and"
35287,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.102941176,"the, of, which, to, in, animals, was"
35288,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.102941176,"that, the, and, may, be, of, to"
35289,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.102941176,"a, group, of, the, sars-like, that, bats"
35290,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.102941176,"a, shows, were, to, of, in, the"
35291,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.102941176,"the, of, and, viruses, in, between, for"
35292,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.102941176,"sars-cov-2, a, and, et, to, that, may"
35293,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.102941176,"and, the, of, to, et, that, sars-cov-2"
35294,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.102941176,"on, the, of, and, that, virus,, by"
35295,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.102941176,"this, of, and, by, a, in, the"
35296,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.102941176,"3, of, the, and, sequences, with, viruses"
35297,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.102941176,"of, the, 3, and, sequences, with, viruses"
35298,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.102941176,"the, and, bat, cov, pangolin, cov), sars"
35299,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.102941176,"the, and, bat, cov, pangolin, cov), viruses"
35300,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.102941176,"the, that, viruses, in, could, and, to"
35301,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.102941176,"be, possible, to, bats, and, are, on"
35302,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.102941176,"the, and, in, to, that, these, are"
35303,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.102941176,"in, the, bat, origin, between, these, and"
35304,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.102941176,"in, the, is, sars-cov-2, that, pangolin, cov"
35305,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.102941176,"in, to, the, is, very, likely, sars-cov-2"
35306,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.102941176,"and, sars-cov-2, are, to, bat, pangolin, in"
35307,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.102941176,"the, and, are, of, bat, that, to"
35308,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.102941176,"and, that, they, the, bat, ratg13, of"
35309,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.102941176,"the, bat, cov, and, cov), sars, pangolin"
35310,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.102941176,"the, bat, cov, and, cov), viruses, pangolin"
35311,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.102941176,"that, the, of, sars-cov-2, and, evidence, to"
35312,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.102941176,"the, and, are, to, that, may, have"
35313,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.102941176,"in, these, and, bat, the, between, origin"
35314,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.102941176,"to, that, the, of, are, likely, sars-cov-2"
35315,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.102941176,"the, of, and, that, virus, with, to"
35316,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.102941176,"of, to, the, that, was, transmitted, from"
35317,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.102941176,"in, sars-cov-2, cov, pangolin, that, the, is"
35318,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.102941176,"in, a, zoonotic, as, to, of, and"
35319,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.102941176,"were, of, sars-cov-2, from, in, and, to"
35320,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.102941176,"sars-cov-2, is, to, very, likely, in, the"
35321,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.102941176,"the, of, that, sars-cov-2, are, likely, to"
35322,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.102941176,"a, of, the, bat, that, not, but"
35323,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.102941176,"to, of, in, southeast, and, it, that"
35324,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.102941176,"the, genetic, sars-cov-2, and, of, virus, to"
35325,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.102941176,"the, in, sars-cov-2, with, furin, cleavage, be"
35326,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.102803738,"in, the, from, that, did, also, virus, was, by, a, is"
35327,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.102803738,"and, the, of, viruses, are, a, that, into, this, in, which"
35328,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.102803738,"from, the, was, to, that, bat, as, and, sars, of, coronavirus"
35329,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.102803738,"in, of, a, bat, with, found, genome, that, yunnan, province, horseshoe"
35330,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.102803738,"a, of, the, this, that, and, are, in, which, viruses, into"
35331,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.102803738,"and, in, to, closely, related, that, the, of, is, bats, are"
35332,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.102803738,"with, the, and, a, to, team, in, sars-cov-2, other, by, at"
35333,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.102803738,"with, the, and, a, to, there, in, sars-cov-2, more, than, other"
35334,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.102803738,"is, also, that, was, from, a, by, the, virus, did, in"
35335,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.102803738,"the, of, coronavirus, that, from, was, to, bat, as, and, sars"
35336,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.102803738,"that, a, horseshoe, bat, found, in, yunnan, province, genome, of, with"
35337,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.102803738,"a, by, from, at, in, china, the, virus, to, of, were"
35338,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.102803738,"in, by, a, team, with, other, and, to, sars-cov-2, at, the"
35339,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.102803738,"there, a, other, to, in, more, with, sars-cov-2, than, the, and"
35340,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.102803738,"at, to, a, from, in, the, virus, by, china, were, of"
35341,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.102803738,"and, the, of, to, are, closely, related, bats, that, in, is"
35342,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.102564103,"coronaviruses, in, a, viruses"
35343,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.102564103,"coronaviruses, a, viruses, in"
35344,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.102564103,"and, very, to, human"
35345,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.102564103,"sars-cov-2, to, human, bat"
35346,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.102564103,"a, and, in, bat"
35347,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.102564103,"sars-cov, and, many, other"
35348,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.102564103,"sars-cov-2, and, to, sars-cov"
35349,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.102564103,"in, the, as, bats"
35350,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.102564103,"for, of, and, were, that, virus, or, with"
35351,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.102564103,"sequences, in, bat, and"
35352,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.102564103,"of, sars-cov-2, to, sars-cov"
35353,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.102564103,"to, of, which, sars-cov-2"
35354,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.102564103,"sars-cov-2, of, and, to"
35355,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.102564103,"of, to, sars-cov-2, bats"
35356,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.102564103,"the, to, sars-, and"
35357,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.102564103,"the, to, sars-, cov-2"
35358,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.102564103,"virus, genome, to, sars-cov-2"
35359,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.102564103,"is, sars-cov-2, more, than"
35360,"civet cats and raccoon dogs  

are the intermediate hosts","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.102564103,"civet, cats, and, the"
35361,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.102564103,"that, be, sars-cov-2, of"
35362,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.102564103,"have, that, a, of"
35363,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.102564103,"have, been, from, is"
35364,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.102564103,"available, to, the, that, sars-cov-2, a, of, origin"
35365,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.102564103,"the, that, have, in, for, of, to, and, a, not, covid-19, an"
35366,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.102564103,"of, sars-cov-2, to, ace2, receptors, which, the, in"
35367,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.102564103,"a, that, virus, other"
35368,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.102564103,"within, sars-cov-2, that, and"
35369,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.102564103,"that, virus, and, naturally"
35370,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.102564103,"virus, that, is, and"
35371,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.102564103,"all, human, to, and"
35372,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.102564103,"sars-cov, sars-cov-2, to, of"
35373,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.102564103,"that, the, it, was"
35374,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.102564103,"on, and, of, bat"
35375,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.102564103,"and, of, natural, evolutionary"
35376,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.102564103,"of, virus, bat, and"
35377,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.102564103,"with, and, sars-cov-2, of"
35378,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.102564103,"sars-cov-2, and, of, transmission"
35379,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.102564103,"the, of, genome, bat"
35380,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.102564103,"in, the, with, genome"
35381,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.102564103,"the, as, in, bats"
35382,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.102564103,"the, zoonotic, host, as"
35383,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.102564103,"that, bats, are, the, of, and, in, for"
35384,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.102564103,"the, pangolins, in, of"
35385,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.102564103,"intermediate, pangolins, the, in"
35386,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.102564103,"intermediate, for, sars-cov-2, the"
35387,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.102564103,"from, as, the, for"
35388,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.102564103,"the, and, had, in"
35389,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.102564103,"the, animal, of, to"
35390,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.102564103,"the, to, were, in"
35391,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.102564103,"in, were, to, and"
35392,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.102564103,"a, to, and, in"
35393,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.102564103,"the, a, to, and"
35394,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.102564103,"the, of, be, and"
35395,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.102564103,"the, reservoirs, of, and"
35396,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.102564103,"and, are, of, the"
35397,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.102564103,"of, and, are, the"
35398,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.102564103,"the, to, and, animals, virus, sars-cov, masked, palm"
35399,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.102564103,"the, covid-19, identity, of"
35400,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.102564103,"the, genomic, only, at"
35401,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.102564103,"the, genomic, of, sars-cov"
35402,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.102564103,"the, of, sars-cov-2, covid-19"
35403,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.102564103,"the, over, identical, to"
35404,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.102564103,"t, is, the, from"
35405,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.102564103,"the, is, from, previously"
35406,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.102564103,"the, is, identical, to"
35407,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",Bats are likely reservoir hosts for SARS-CoV-2,0.102564103,"sars-cov-2, reservoir, are, likely"
35408,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.102564103,"a, origin, sars-cov-2, the"
35409,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.102564103,"the, sars-cov-2, coronavirus, from"
35410,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.102564103,"sars-cov-2, the, with, to"
35411,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.102564103,"the, into, to, and"
35412,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.102564103,"to, sars-cov-2,, of, which"
35413,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.102564103,"the, of, to, sars-cov-2,"
35414,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.102564103,"the, of, bat, that"
35415,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.102564103,"that, the, bat, of"
35416,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.102564103,"that, sars-cov-2, bat, to"
35417,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.102564103,"natural, that, the, for"
35418,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","civet cats and raccoon dogs  

are the intermediate hosts",0.102564103,"the, and, civet, cats"
35419,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.102564103,"and, from, in, to, that, the, coronavirus, are"
35420,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.102564103,"the, of, to, animal"
35421,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","with the first case being linked to  

a seafood market",0.102564103,"a, linked, to, the"
35422,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.102564103,"sars-cov-2, been, in, bats"
35423,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.102564103,"the, one, in, and"
35424,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.102564103,"one, a, which, in"
35425,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.102564103,"other, a, virus, that"
35426,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.102564103,"the, that, released, by, who, a, not, had"
35427,Bats are likely reservoir hosts for SARS-CoV-2,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.102564103,"are, likely, reservoir, sars-cov-2"
35428,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.102564103,"sars-cov-2, origin, of, to, a, available, that, the"
35429,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.102564103,"of, that, to, the"
35430,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.102564103,"the, spread, and, only"
35431,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.102564103,"that, has, genome, sars-cov-2"
35432,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.102564103,"the, and, are, that"
35433,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.102564103,"sars-cov-2, has, natural, and"
35434,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.102564103,"the, of, coronavirus, bat"
35435,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.102564103,"the, and, have, not"
35436,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.102564103,"was, that, the, sars-cov-2"
35437,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.102564103,"the, sars-cov-2, of, that"
35438,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.102564103,"from, with, sars-cov-2, s"
35439,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.102564103,"sars-cov-2, and, bats, of"
35440,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.102564103,"two, from, the, bat"
35441,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.102564103,"the, lineage, bat, from"
35442,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.102564103,"in, the, from, and, a, of, both, sars-cov-2"
35443,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.102564103,"are, that, virus., sars-cov-2, from, and, viruses, in"
35444,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.102564103,"a, of, the, at, are, by, that, origin"
35445,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.102564103,"of, sars-cov-2, the, animals"
35446,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.102564103,"be, that, of, sars-cov-2"
35447,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.102564103,"transmission, of, sars-cov-2, and"
35448,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.102564103,"that, be, the, sars-cov-2"
35449,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.102564103,"the, of, and, that, into, in, humans, with"
35450,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.102564103,"the, are, in, a"
35451,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.102564103,"that, the, closely, a"
35452,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.102564103,"the, origin, in, and"
35453,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.102564103,"a, of, geographic, in"
35454,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.102564103,"at, in, the, with"
35455,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.102564103,"the, a, of, from"
35456,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.102564103,"a, of, the, presence"
35457,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.102564103,"from, at, the, huanan, market, of, a, was"
35458,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.102564103,"the, and, in, animal"
35459,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.102564103,"the, re-, these, viruses"
35460,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.102564103,"to, the, in, these"
35461,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.102564103,"sars-cov-2, within, and, that"
35462,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.102564103,"the, and, that, was"
35463,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.102564103,"and, at, the, huanan, market, in, was, animal"
35464,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.102564103,"in, reservoirs, and, the"
35465,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.102564103,"sars-cov-2, was, the, in"
35466,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.102564103,"the, that, likely, than"
35467,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.102564103,"in, and, a, even"
35468,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.102564103,"of, in, to, from"
35469,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.102564103,"sars-cov-2, and, humans, from"
35470,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.102564103,"of, sars-cov-2, from, and"
35471,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.102564103,"of, zoonotic, and, in"
35472,"Bats have been reported as being the rich source of 

coronaviruses","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.102564103,"as, the, source, of"
35473,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.102564103,"a, from, four, sars-cov-2"
35474,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.102564103,"a, that, sars-cov-2, the"
35475,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.102564103,"the, of, natural, or"
35476,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.102564103,"the, of, evidence, natural"
35477,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.102564103,"the, of, scientific, evidence"
35478,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.102564103,"con-, to, the, of"
35479,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.102564103,"covid-19, to, the, huanan"
35480,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.102564103,"a, of, the, from, sars-cov-2, and, in, both"
35481,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.102564103,"in, the, to, that, sars-cov-2, of, sars-, cov-2"
35482,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.102564103,"from, in, to, that, the, of, sars-, sars-cov-2"
35483,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.102564103,"from, virus., that, sars-cov-2, and, are, in, viruses"
35484,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.102564103,"and, from, in, to, that, is, are, sars-cov-2"
35485,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.102564103,"sars-cov-2, in, their, is"
35486,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.102564103,"to, in, humans, spillover"
35487,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.102564103,"that, the, humans, from"
35488,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.102564103,"evidence, that, in, the"
35489,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.102564103,"the, of, to, is, likely, a, that, this"
35490,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.102564103,"in, animals, but, is, of, the, virus, and"
35491,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.102564103,"the, of, is, most, on, a, that, not"
35492,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.102564103,"from, to, a, in"
35493,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.102564103,"to, that, in, naturally"
35494,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.102564103,"that, animal, is, a"
35495,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.102564103,"covid-19, that, is, to"
35496,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.102564103,"has, a, and, was"
35497,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.102564103,"has, that, the, a"
35498,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.102564103,"that, and, the, virus"
35499,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.102564103,"huanan, seafood, the, and"
35500,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.102564103,"that, and, were, seafood"
35501,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.102564103,"the, huanan, seafood, that"
35502,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.102564103,"from, were, and, the"
35503,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.102564103,"that, also, and, the"
35504,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.102564103,"to, that, a, of"
35505,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.102564103,"to, and, that, a"
35506,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.102564103,"a, of, that, and"
35507,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.102564103,"to, zoonotic, and, of"
35508,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.102564103,"a, of, and, to"
35509,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.102564103,"and, coronaviruses, to, of"
35510,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.102564103,"human, and, to, very"
35511,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.102564103,"to, is, from, and"
35512,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.102564103,"the, was, that, and"
35513,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.102564103,"a, that, to, and"
35514,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.102564103,"a, the, coronavirus, sequence"
35515,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.102564103,"was, the, 96.2%, genome"
35516,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.102564103,"the, known, of, to"
35517,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.102564103,"animal, known, the, to"
35518,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.102564103,"to, the, host, pangolin,"
35519,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.102564103,"a, with, the, pandemic"
35520,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.102564103,"indicates, that, the, of"
35521,hese close genetic relations suggest that they all have their ecological origin in bat populations,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.102564103,"close, that, they, in"
35522,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.102564103,"the, virus, market, to"
35523,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.102564103,"the, of, with, by"
35524,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.102564103,"the, of, from, and"
35525,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.102564103,"is, from, the, of"
35526,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.102564103,"has, an, to, and"
35527,The COVID-19 most likely developed from bat origin coronaviruses,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.102564103,"the, covid-19, from, bat"
35528,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.102564103,"from, and, to, for, the, of, that, a"
35529,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Bats have been reported as being the rich source of 

coronaviruses",0.102564103,"the, as, source, of"
35530,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Bats have been reported as being the rich source of 

coronaviruses",0.102564103,"have, the, of, as"
35531,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.102564103,"similarity, to, a, from"
35532,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.102564103,"of, the, their, spike"
35533,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.102564103,"from, sars-cov-2, isolated, with"
35534,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.102564103,"that, the, sars-cov-2, comparative"
35535,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.102564103,"to, and, the, is"
35536,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.102564103,"is, the, be, and"
35537,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.102564103,"in, from, a, to"
35538,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.102564103,"and, are, the, transmitted"
35539,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.102564103,"the, bats, are, virus"
35540,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.102564103,"the, of, and, in, animals, virus, but, is"
35541,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.102564103,"to, bats,, that, in"
35542,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.102564103,"and, virus, that, naturally"
35543,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.102564103,"and, origin, the, in"
35544,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.102564103,"that, in, naturally, to"
35545,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.102564103,"to, the, in, animals"
35546,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.102564103,"the, in, and, had"
35547,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.102564103,"and, in, the, animal"
35548,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.102564103,"the, huanan, seafood, and"
35549,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.102564103,"the, bat, cov, and"
35550,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.102564103,"bat, cov, the, with"
35551,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.102564103,"the, and, that, of"
35552,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.102564103,"that, to, bats, and"
35553,"According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.102564103,"according, to, sars-cov, is"
35554,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.102564103,"the, intermediate, host, for"
35555,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.102564103,"have, in, the, or"
35556,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.102564103,"only, and, spread, the"
35557,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.102564103,"therefore, be, that, to"
35558,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.102564103,"was, that, the, it"
35559,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.102564103,"the, virus, was, that"
35560,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.102564103,"the, virus, in, market"
35561,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.102564103,"virus, that, the, in"
35562,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.102564103,"that, the, hosts, for"
35563,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.102564103,"human, sars-cov-2, to, bat"
35564,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.102564103,"identical, the, to, over"
35565,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.102564103,"the, bat, coronavirus, of"
35566,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.102564103,"the, of, sars-cov-2, genome"
35567,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.102564103,"sars-cov-2, to, the, bat"
35568,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.102564103,"according, to, is, sars-cov"
35569,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.102564103,"human, and, to, in"
35570,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.102564103,"and, all, to, human"
35571,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.102564103,"humans, in, and, to"
35572,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.102564103,"in, to, spillover, humans"
35573,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.102564103,"and, in, spillover, to"
35574,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Coronaviruses are naturally hosted and developmentally 

formed by bats.",0.102564103,"formed, by, and, are"
35575,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.102564103,"the, of, that, it"
35576,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.102564103,"the, from, of, bat"
35577,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.102564103,"the, from, that, bat"
35578,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.102564103,"that, may, have, to"
35579,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.102564103,"in, a, the, are"
35580,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.102564103,"a, of, the, nearly"
35581,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.102564103,"the, viruses, in, of"
35582,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.102564103,"the, of, viruses, same"
35583,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.102564103,"in, the, from, a"
35584,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.102564103,"are, the, a, of"
35585,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.102564103,"on, and, bat, of"
35586,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.102564103,"bats, most, likely, of"
35587,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.102564103,"have, shown, that, of"
35588,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.102564103,"is, by, bat, collected"
35589,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.102564103,"its, in, the, which"
35590,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.102564103,"a, that, to, is"
35591,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.102564103,"virus, is, to, that"
35592,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.102564103,"a, the, spillover, to"
35593,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.102564103,"the, is, it, to"
35594,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.102564103,"the, to, genus, bat"
35595,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.102564103,"sars-cov-2, are, to, the"
35596,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.102564103,"of, from, in, to"
35597,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.102564103,"in, the, to, sars"
35598,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.102564103,"to, the, of, is"
35599,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.102564103,"the, of, is, in"
35600,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.102564103,"in, that, they, close"
35601,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.102564103,"in, suggest, bat, origin"
35602,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.102564103,"market, in, the, virus"
35603,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.102564103,"or, in, to, virus"
35604,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.102564103,"and, that, from, the"
35605,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.102564103,"sars-cov-2, humans, from, and"
35606,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.102564103,"the, that, from, humans"
35607,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.102564103,"the, is, that, and"
35608,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.102564103,"the, from, and, sars-cov-2"
35609,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.102564103,"animal, and, the, that"
35610,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.102564103,"was, isolated, in, and"
35611,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.102564103,"many, such, as, and"
35612,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.102564103,"the, and, that, viruses"
35613,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.102564103,"that, the, and, viruses"
35614,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.102564103,"of, the, to, that"
35615,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.102564103,"of, to, the, that"
35616,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.102564103,"the, sequence, of, sars-cov-2"
35617,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.102564103,"has, the, of, with"
35618,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.102564103,"and, human, of, the"
35619,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.102564103,"the, of, covid-19, identity"
35620,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.102564103,"of, the, covid-19, approximately"
35621,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.102564103,"that, the, to, bat"
35622,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.102564103,"sars-cov-2, a, and, the"
35623,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.102564103,"the, a, from, sars-cov-2"
35624,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.102564103,"the, sars-cov-2, other, natural"
35625,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.102564103,"to, animal, in, zoonotic"
35626,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.102564103,"at, the, only, genomic"
35627,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.102564103,"is, that, the, bat"
35628,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.102564103,"of, the, and, virus"
35629,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.102564103,"are, and, the, transmitted"
35630,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.102564103,"the, animal, of, is"
35631,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.102564103,"are, the, of, which"
35632,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.102564103,"the, which, and, wild"
35633,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.102564103,"that, were, seafood, and"
35634,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.102564103,"the, of, sars-cov, genomic"
35635,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.102564103,"open, reading, frame, of"
35636,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.102564103,"a, that, sars-cov-2, is"
35637,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.102564103,"of, the, nearly, a"
35638,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.102564103,"the, analysis, that, and"
35639,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.102564103,"of, the, con-, to"
35640,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.102564103,"most, likely, bats, of"
35641,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.102564103,"of, bats, to, the"
35642,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.102564103,"the, pangolins, of, to"
35643,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.102564103,"of, the, most, likely"
35644,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.102564103,"pangolins, be, hosts, are"
35645,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Bats are natural hosts of many of the known  

coronaviruses",0.102564103,"are, of, the, bats"
35646,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Bats are natural hosts of many of the known  

coronaviruses",0.102564103,"of, are, the, hosts"
35647,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.102564103,"this, the, as, intermediate"
35648,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.102564103,"with, the, sars-cov-2, sequence"
35649,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.102564103,"the, coronavirus, sequence, a"
35650,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.102564103,"a, has, sars-cov-2, the"
35651,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.102564103,"series, is, the, of"
35652,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.102564103,"in, of, to, the"
35653,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.102564103,"results, that, of, the"
35654,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.102564103,"the, of, a, these"
35655,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.102564103,"be, a, the, that"
35656,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.102564103,"that, the, huanan, seafood"
35657,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.102564103,"to, the, huanan, seafood"
35658,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.102564103,"linked, to, the, of"
35659,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.102564103,"the, is, of, a"
35660,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.102564103,"the, covid-19, to, huanan"
35661,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.102564103,"the, in, market, at"
35662,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.102564103,"the, was, and, of"
35663,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.102564103,"of, linked, to, the"
35664,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.102564103,"the, sars-cov-2, and, cov"
35665,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.102564103,"the, of, from, bat"
35666,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.102564103,"sars-cov-2, a, the, an"
35667,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.102564103,"sars-cov-2, been, bats, in"
35668,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.102564103,"the, of, at, that"
35669,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.102564103,"even, a, and, in"
35670,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.102564103,"a, of, was, on"
35671,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.102564103,"viruses, of, natural, the"
35672,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.102564103,"the, a, as, from"
35673,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.102564103,"the, of, and, from"
35674,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.102564103,"the, to, was, a"
35675,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.102564103,"coronavirus, to, by, the"
35676,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.102564103,"the, to, a, coronavirus"
35677,"zoonotic corona- 

viruses have become an increasing threat to human health,","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.102564103,"viruses, have, to, human"
35678,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.102564103,"a, virus, found, of"
35679,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.102564103,"the, are, by, of"
35680,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.102564103,"bats, are, the, a"
35681,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.102564103,"the, virus, new, of"
35682,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.102564103,"and, bat, in, a"
35683,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.102564103,"zoonotic, of, in, and"
35684,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.102564103,"for, related, to, were"
35685,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.102564103,"the, to, and, wild"
35686,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.102564103,"recent, the, for, sars-cov-2"
35687,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.102564103,"recent, of, in, sars-cov-2"
35688,"bats are also important reservoir species for a great 

range of coronaviruses","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.102564103,"bats, for, a, of"
35689,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.102564103,"a, sars-cov-2, to, sars-cov"
35690,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.102564103,"similarity, sars-cov-2, genome, to"
35691,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.102564103,"the, sars-cov-2, intermediate, for"
35692,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.102564103,"in, were, sars-cov-2, the"
35693,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.102564103,"a, the, in, sars-cov-2"
35694,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.102564103,"the, in, pangolins, sars-cov-2"
35695,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.102564103,"the, similarity, sars-cov-2, cov"
35696,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.102564103,"sars-cov-2, cov, a, the"
35697,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.102564103,"a, bat, yunnan, of"
35698,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.102564103,"sars-cov-2, the, of, covid-19"
35699,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.102564103,"the, of, covid-19, wuhan"
35700,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.102564103,"the, sars-cov-2, or, of"
35701,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.102564103,"the, to, sars-cov-2, by"
35702,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.102564103,"related, to, the, is"
35703,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.102564103,"that, sars-cov-2, has, genome"
35704,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.102564103,"a, of, virus, found"
35705,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.102564103,"of, yunnan, a, bat"
35706,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.102564103,"of, a, with, sars-cov-2"
35707,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.102564103,"similarity, of, bat, that"
35708,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.102564103,"is, similar, sars-cov-2, the"
35709,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.102564103,"to, is, that, similar"
35710,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.102564103,"the, to, with, market"
35711,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.102564103,"to, the, market, virus"
35712,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.102564103,"virus, with, to, the"
35713,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.102564103,"that, is, a, animal"
35714,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.102564103,"animal, the, of, is"
35715,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.102564103,"the, sequence, of, and"
35716,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.102564103,"the, in, to, of"
35717,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","bats are also important reservoir species for a great 

range of coronaviruses",0.102564103,"of, bats, a, for"
35718,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","bats are also important reservoir species for a great 

range of coronaviruses",0.102564103,"of, are, a, species"
35719,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.102564103,"were, from, the, and"
35720,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.102564103,"the, of, to, ace2"
35721,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.102564103,"the, from, species, in"
35722,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.102564103,"two, bat, the, from"
35723,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.102564103,"s, the, sequence, with"
35724,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.102564103,"s, the, and, bat"
35725,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.102564103,"the, bat, sequence, s"
35726,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.102564103,"of, the, has, with"
35727,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.102564103,"the, rbd, of, with"
35728,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.102564103,"of, sars-cov-2, the, protein"
35729,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.102564103,"that, to, therefore, be"
35730,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.102564103,"the, for, to, a"
35731,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.102564103,"to, the, sars-cov-2, a"
35732,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.102564103,"the, sars-cov-2, to, by, may, be, of, and"
35733,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.102564103,"the, as, host, zoonotic"
35734,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.102564103,"and, sars-cov-2, to, in"
35735,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.102564103,"at, the, to, in"
35736,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.102564103,"at, the, market, in"
35737,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.102564103,"sars-cov-2, found, with, to"
35738,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.102564103,"of, the, in, from"
35739,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.102564103,"the, of, that, in, a, could, and, to"
35740,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.102564103,"a, from, in, that, the, to, of, bats"
35741,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.102564103,"of, natural, which, the"
35742,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.102564103,"the, bats, are, for"
35743,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.102564103,"coronaviruses, the, of, sars-cov-2."
35744,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.102564103,"the, and, one, in"
35745,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.102564103,"the, and, in, china"
35746,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Bats are the second  

largest order of mammals, with over 1,230 species.",0.102564103,"with, the, of, bats"
35747,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.102564103,"of, sars-cov-2, the, which"
35748,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.102564103,"and, viruses, of, the"
35749,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.102564103,"the, of, for, and"
35750,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.102564103,"viruses, of, the, and"
35751,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.102564103,"that, bat, in, sars-cov-2"
35752,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.102564103,"are, including, the, and"
35753,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.102564103,"the, were, to, in"
35754,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.102564103,"were, to, related, for"
35755,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.102564103,"the, in, to, were"
35756,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.102564103,"the, in, and, china"
35757,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.102564103,"and, the, in, china"
35758,"bats are also important reservoir species for a great 

range of coronaviruses","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.102564103,"are, species, a, of"
35759,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.102564103,"in, the, same, of, a, bat, by, viruses, similar, and, this, species"
35760,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.102564103,"in, the, of, as, a, that, to, closely"
35761,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.102564103,"sars-cov-2, to, of, which"
35762,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.102564103,"sars-cov-2,, which, to, of"
35763,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.102564103,"a, of, with, sars-cov-2"
35764,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.102564103,"have, a, which, of"
35765,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.102564103,"the, coronavirus, to, by"
35766,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.102564103,"sars-cov-2, highest, similarity, to"
35767,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.102564103,"are, of, by, the"
35768,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.102564103,"to, by, the, sars-cov-2"
35769,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.102564103,"the, similarity, of, to"
35770,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.102564103,"the, related, to, also"
35771,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.102564103,"of, the, with, through"
35772,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.102564103,"ace2, of, to, the"
35773,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.102564103,"the, of, rbd, with"
35774,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.102564103,"that, of, the, through"
35775,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.102564103,"of, that, the, to"
35776,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.102564103,"of, the, that, with"
35777,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","This suggests that the BANAL series may be able to directly infect  

humans.",0.102564103,"the, be, to, that"
35778,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.102564103,"suggest, that, to, in"
35779,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.102564103,"is, the, in, from"
35780,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.102564103,"the, is, of, from"
35781,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.102564103,"the, is, series, of"
35782,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.102564103,"the, of, from, in"
35783,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.102564103,"the, is, of, in"
35784,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.102564103,"their, the, spike, of"
35785,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.102564103,"the, virus, of, to"
35786,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.102564103,"most, of, the, by"
35787,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.102564103,"and, was, isolated, in"
35788,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.102564103,"the, is, virus, to"
35789,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.102564103,"known, in, the, to"
35790,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.102564103,"the, virus, be, in"
35791,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.102564103,"the, covid-19, approximately, of"
35792,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.102564103,"the, of, is, its"
35793,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.102564103,"the, is, be, and"
35794,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.102564103,"that, the, were, with"
35795,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.102564103,"cases, at, the, that, or, was, zoonotic, of, into, in, this, a"
35796,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.102564103,"of, and, that, for, virus, were, with, or"
35797,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.102564103,"the, of, with, and, that, into, humans, in"
35798,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.102564103,"that, the, of, in, as, closely, a, to"
35799,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.102564103,"the, that, of, human, and, in, sample, at"
35800,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.102564103,"this, of, and, similar, viruses, by, bat, a, species, in, the, same"
35801,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.102564103,"of, a, at, the, huanan, market, was, from"
35802,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.102564103,"the, animal, at, huanan, market, was, in, and"
35803,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.102564103,"of, covid-19, for, to, a, have, that, not, in, an, and, the"
35804,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.102564103,"who, not, a, that, the, released, had, by"
35805,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.102564103,"of, covid-19, that, is, to, the, and, for"
35806,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.102564103,"the, animal, to, known"
35807,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.102564103,"to, in, and, spillover"
35808,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.102564103,"the, sars, in, to"
35809,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.102564103,"that, the, and, animal"
35810,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.102564103,"the, to, known, in"
35811,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.102564103,"in, the, of, at, that, sample, human, and"
35812,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.102564103,"this, that, a, zoonotic, the, was, into, or, cases, of, in, at"
35813,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.102564103,"the, of, sars-cov-2, likely, a, or, that, this"
35814,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.102564103,"the, that, natural, for"
35815,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.102564103,"a, the, pandemic, with"
35816,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.102564103,"with, to, sars-cov-2, found"
35817,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.102564103,"most, to, humans, through"
35818,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.102564103,"that, and, bats, to"
35819,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.102564103,"the, in, and, reservoirs"
35820,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.102564103,"the, natural, of, which"
35821,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.102564103,"the, to, which, and"
35822,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.102564103,"a, in, and, was"
35823,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.102564103,"was, a, has, and"
35824,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.102564103,"that, a, sars-cov-2, collected"
35825,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.102564103,"a, of, to, the, likely, that, this, is"
35826,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.102564103,"a, the, of, on, that, not, is, most"
35827,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.102564103,"the, likely, that, or, of, sars-cov-2, this, a"
35828,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.102564103,"to, this, not, the, of, that, sars-cov-2, a"
35829,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.102564103,"a, that, sars-cov-2, laboratory"
35830,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.102564103,"is, the, previously, from"
35831,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.102564103,"that, not, from, the"
35832,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.102564103,"genetic, the, that, from"
35833,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.102564103,"the, is, that, virus"
35834,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.102564103,"that, bat, similarity, of"
35835,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.102564103,"the, to, similarity, of"
35836,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.102564103,"of, the, its, is"
35837,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.102564103,"from, that, identical, to"
35838,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","Malayan pangolins (Manis javanica)  

illegally imported into Guangdong province  

contain coronaviruses similar to SARS- 

CoV-22",0.102564103,"malayan, pangolins, (manis, coronaviruses"
35839,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.102564103,"in, to, that, the, of, is, natural, sars-cov-2"
35840,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.102564103,"and, evolutionary, natural, of"
35841,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.102564103,"through, that, the, of"
35842,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.102564103,"to, the, of, pangolins"
35843,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.102564103,"pangolins, sars-cov-2, the, in"
35844,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","In the 

case of MERS, dromedaries were the principal host.",0.102564103,"the, of, case, in"
35845,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.102564103,"the, bat, of, genome"
35846,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.102564103,"a, that, the, closely"
35847,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.102564103,"this, that, originated, in"
35848,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.102564103,"to, could, a, of, in, the, and, that"
35849,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.102564103,"of, the, sequence, and"
35850,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.102564103,"the, and, to, sars-"
35851,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.102564103,"wild, and, the, which"
35852,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.102564103,"analysis, the, that, and"
35853,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.102564103,"to, the, wild, and"
35854,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.102564103,"and, to, which, the"
35855,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.102564103,"the, analysis, that, covid-19"
35856,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.102564103,"the, from, bats,, and"
35857,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.102564103,"from, intermediate, as, for, the, of, that, a"
35858,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.102564103,"of, which, have, a"
35859,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.102564103,"these, re-, viruses, the"
35860,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.102564103,"of, the, same, viruses"
35861,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",Bats are hosts of many coronaviruses,0.102564103,"of, bats, hosts, are"
35862,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.102564103,"humans, through, to, most"
35863,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.102564103,"the, seafood, market, to"
35864,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.102564103,"the, of, most, by"
35865,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.102564103,"was, in, by, the"
35866,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.102564103,"of, by, the, in"
35867,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.102564103,"that, the, of, been"
35868,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.102564103,"that, is, covid-19, to"
35869,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.102564103,"the, is, that, for, of, to, and, covid-19"
35870,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.102564103,"similar, of, and, bat"
35871,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.102564103,"of, the, emergence, and, viruses, similar, to, in"
35872,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.102564103,"bats, are, for, the, of, and, in, that"
35873,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.102564103,"the, wuhan, of, covid-19"
35874,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.102564103,"reported, that, the, to, with, in, this, of"
35875,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.102564103,"bats, of, known, the"
35876,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.102564103,"the, rhinolophus, in, china"
35877,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.102564103,"bat, the, from, lineage"
35878,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.102564103,"collected, is, by, bat"
35879,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.102564103,"in, from, species, the"
35880,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.102564103,"in, the, rhinolophus, china"
35881,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.102564103,"is, the, bat, in"
35882,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.102564103,"the, in, was, by"
35883,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.102564103,"virus, in, or, to"
35884,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.102564103,"animals, virus, to, sars-cov, and, the, masked, palm"
35885,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.102564103,"the, of, in, and"
35886,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.102564103,"of, a, was, in"
35887,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.102564103,"is, from, have, been"
35888,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.102564103,"is, sars-cov-2, in, their"
35889,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.102564103,"have, been, sars-cov-2, the"
35890,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.102564103,"s, with, sars-cov-2, from"
35891,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.102564103,"the, is, similar, sars-cov-2"
35892,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.102564103,"in, the, pangolins, intermediate"
35893,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.102564103,"between, the, and, an"
35894,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.102564103,"the, that, and, a"
35895,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.102564103,"a, of, the, outbreak"
35896,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.102564103,"the, also, related, to"
35897,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.102564103,"also, a, for, the"
35898,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.102564103,"in, is, the, and"
35899,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.102564103,"on, in, the, and"
35900,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","zoonotic corona- 

viruses have become an increasing threat to human health,",0.102564103,"have, human, to, viruses"
35901,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.102564103,"zoonotic, of, and, to"
35902,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.102564103,"zoonotic, and, the, to"
35903,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.102564103,"to, the, of, and"
35904,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.102564103,"the, of, virus, for"
35905,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.102564103,"was, on, a, of"
35906,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.102564103,"a, origin, of, the, by, that, are, at"
35907,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.102564103,"the, most, are, in"
35908,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.102564103,"sars-cov-2, that, to, bat"
35909,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.102564103,"a, is, to, that"
35910,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.102564103,"a, that, sars-cov-2, collected"
35911,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.102564103,"to, that, sars-cov-2, directly"
35912,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.102564103,"the, of, is, with"
35913,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.102564103,"to, suggest, that, in"
35914,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.102564103,"the, a, that, has"
35915,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.102564103,"that, the, has, of"
35916,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.102564103,"and, have, not, the"
35917,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.102564103,"the, for, a, of, to, that, from, and"
35918,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.102564103,"the, of, sars-cov-2, to, a, that, this, not"
35919,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.102564103,"of, that, the, a, from, as, intermediate, for"
35920,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.102564103,"of, the, was, sars-cov-2"
35921,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.102564103,"the, of, not, sars-cov-2"
35922,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.102564103,"the, from, as, for"
35923,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.102564103,"in, that, sars-cov-2, animal"
35924,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.102564103,"of, the, and, human"
35925,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.102564103,"the, most, likely, of"
35926,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.102564103,"to, that, and, sars-cov-2"
35927,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.102564103,"from, identical, to, that"
35928,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.102564103,"bat, of, sars-cov-2, genome"
35929,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.102564103,"the, other, sars-cov-2, natural"
35930,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.102564103,"the, of, to, genetic"
35931,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.102564103,"to, the, of, with"
35932,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.102564103,"of, similar, bat, and"
35933,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.102564103,"sars-cov-2, of, which, to, ace2, receptors, in, the"
35934,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.102564103,"the, of, sars-cov-2, animals"
35935,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.102564103,"these, in, to, the"
35936,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.102564103,"the, sars-cov-2, was, in"
35937,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.102564103,"the, to, in, animals"
35938,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.102564103,"the, of, sars-cov-2, to, may, be, and, by"
35939,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.102564103,"the, reported, to, this, that, in, with, of"
35940,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.102564103,"this, the, with, sars-cov-2, that, are, more, than"
35941,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.102564103,"the, that, be, sars-cov-2"
35942,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.102564103,"comparative, that, sars-cov-2, the"
35943,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.102564103,"recent, sars-cov-2, the, for"
35944,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.102564103,"that, the, from, bat"
35945,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.102564103,"the, likely, than, that"
35946,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.102564103,"are, the, virus, bats"
35947,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.102564103,"bats, are, the, for"
35948,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.102564103,"to, from, a, of, in, bats, the, that"
35949,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.102564103,"the, for, that, hosts"
35950,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.102564103,"bats, are, a, the"
35951,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.102564103,"virus, and, bat, of"
35952,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.102564103,"to, bat, the, genus"
35953,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.102564103,"the, a, sars-cov-2, origin"
35954,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.102564103,"of, the, in, by"
35955,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.102564103,"a, the, outbreak, of"
35956,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.102564103,"sars-cov-2, the, origin, bat"
35957,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.102564103,"which, a, one, in"
35958,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.102564103,"a, from, to, similarity"
35959,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.102564103,"in, of, a, was"
35960,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.102564103,"are, be, hosts, pangolins"
35961,"Coronaviruses are naturally hosted and developmentally 

formed by bats.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.102564103,"are, and, formed, by"
35962,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.102564103,"the, to, have, been"
35963,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.102564103,"the, sars-cov-2, have, been"
35964,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.102564103,"to, sars-cov-2, the, we"
35965,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.102564103,"the, have, to, as"
35966,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.102564103,"viruses, the, that, and"
35967,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.102564103,"bat, cov, sars-cov-2, ratg13"
35968,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.102564103,"is, sars-cov-2, the, of"
35969,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.102564103,"is, more, than, sars-cov-2"
35970,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.102564103,"that, are, more, than, the, sars-cov-2, with, this"
35971,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.102564103,"the, coronavirus, from, sars-cov-2"
35972,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.102564103,"from, bats, the, of"
35973,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.102564103,"this, that, the, sars-cov-2"
35974,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.102564103,"the, host, to, pangolin,"
35975,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.102564103,"or, in, the, have"
35976,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.102564103,"in, sars-, cov-2, the, of, that, sars-cov-2, to"
35977,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.102564103,"this, the, of, pangolin"
35978,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.102564103,"sars-cov-2, similarity, the, cov"
35979,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.102564103,"s, the, bat, and"
35980,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.102564103,"bat, origin, sars-cov-2, the"
35981,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.102564103,"that, the, sars-cov-2, has"
35982,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.102564103,"this, sars-cov-2, the, that"
35983,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.102564103,"the, of, sars-cov-2, or"
35984,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.102564103,"that, in, this, originated"
35985,evidence suggests bats as its origin,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.102564103,"evidence, bats, as, origin"
35986,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.102564103,"in, bat, sequences, and"
35987,hese close genetic relations suggest that they all have their ecological origin in bat populations,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.102564103,"suggest, origin, in, bat"
35988,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.102564103,"that, the, and, also"
35989,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.102564103,"to, highest, similarity, sars-cov-2"
35990,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.102564103,"sars-cov, and, sars-cov-2, to"
35991,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.102564103,"is, identical, the, to"
35992,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.102564103,"with, the, of, is"
35993,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.102564103,"of, the, with, by"
35994,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.102564103,"of, sars-cov-2, in, and"
35995,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.102564103,"evidence, the, that, in"
35996,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.102564103,"sars-cov-2, that, and, the"
35997,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.102564103,"and, in, the, that"
35998,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.102564103,"the, in, from, a"
35999,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.102564103,"that, a, of, have"
36000,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.102564103,"of, the, are, a"
36001,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.102564103,"isolated, from, with, sars-cov-2"
36002,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.102564103,"the, and, with, sars-cov-2"
36003,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.102564103,"sars-cov-2, is, the, with"
36004,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.102564103,"the, sars-cov-2, is, for"
36005,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.102564103,"the, is, and, with"
36006,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.102564103,"in, the, sars-cov-2, to"
36007,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.102564103,"identical, to, in, the"
36008,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.102564103,"the, for, that, might"
36009,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.102564103,"the, virus, in, and"
36010,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.102564103,"of, virus, the, new"
36011,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.102564103,"that, the, sars-cov-2, to"
36012,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.102564103,"sars-cov-2, to, bats, of"
36013,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.102564103,"sars-cov-2,, the, to, of"
36014,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.102564103,"that, sars-cov-2, to, directly"
36015,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.102564103,"the, as, intermediate, this"
36016,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.102564103,"sars-cov-2, to, be, is"
36017,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.102564103,"to, that, sars-cov-2, be"
36018,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.102564103,"sars-cov-2, bat, be, the"
36019,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.102564103,"bat, of, sars-cov-2, the"
36020,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.102564103,"the, sars-cov-2, an, a"
36021,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.102564103,"between, an, and, the"
36022,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.102564103,"of, the, scientific, evidence"
36023,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.102564103,"for, the, of, virus"
36024,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.102564103,"to, the, it, is"
36025,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.102564103,"sars-cov-2, bat, in, of"
36026,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.102564103,"sars-cov-2, a, of, from"
36027,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.102564103,"geographic, a, of, in"
36028,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.102564103,"four, a, sars-cov-2, from"
36029,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.102564103,"recent, sars-cov-2, in, of"
36030,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.102564103,"sars-cov-2, bat, coronaviruses, of"
36031,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.102564103,"the, for, a, also"
36032,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.102564103,"with, the, in, genome"
36033,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.102564103,"with, at, the, in"
36034,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.102564103,"the, genome, was, 96.2%"
36035,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.102564103,"was, which, the, in"
36036,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.102564103,"in, the, coronavirus, that, are, from, to, and"
36037,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.102564103,"from, in, sars-, the, of, that, sars-cov-2, to"
36038,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.102564103,"are, that, sars-cov-2, to, from, and, is, in"
36039,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.102564103,"to, sars-cov-2, in, the, that, is, of, natural"
36040,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.102564103,"s, the, bat, sequence"
36041,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.102564103,"that, is, similar, to"
36042,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.102564103,"have, that, may, to"
36043,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.102564103,"have, to, as, the"
36044,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.102564103,"viruses, similar, to, the, in, of, and, emergence"
36045,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.102564103,"coronaviruses, of, to, and"
36046,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.102564103,"the, of, coronaviruses, sars-cov-2."
36047,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.102564103,"of, bat, coronaviruses, sars-cov-2"
36048,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.102409639,"in, a, of, one, to, the, collected, samples, from, tested, positive, for, among, and, sars, at, were"
36049,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.102409639,"a, of, the, at, and, were, in, to, sars, samples, for, one, from, tested, positive, collected, among"
36050,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.102362205,"the, on, most, and, were, in, of, a, data, we, that, at, virus"
36051,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.102362205,"in, the, animals, live, of, that, market, was, to, were, by, a, evidence"
36052,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.102362205,"that, the, of, market, in, was, to, live, animals, were, evidence, a, by"
36053,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.102362205,"the, from, and, were, in, with, of, a, contained, as, to, that, virus"
36054,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.102362205,"bats, on, the, infected, by, of, are, to, as, and, in, other, mammals"
36055,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.102362205,"the, are, to, in, of, as, mammals, on, bats, infected, by, and, other"
36056,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.102362205,"a, at, the, of, and, in, data, on, we, virus, that, were, most"
36057,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.102362205,"the, of, and, were, that, virus, from, contained, a, in, with, as, to"
36058,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.102272727,"in, a, of, for, sars-cov-2, to, novel, origin, that"
36059,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.102272727,"and, the, of, viruses, are, as, bats, they, other"
36060,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.102272727,"the, in, reservoir, likely, was, that, animal, and, market"
36061,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.102272727,"the, of, to, it, is, that, as, for, its"
36062,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.102272727,"the, viruses, are, closely, related, to, sars-cov-2, by, of"
36063,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.102272727,"and, the, of, to, a, with, that, close, in"
36064,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.102272727,"the, animals, to, in, likely, that, virus, were, and"
36065,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.102272727,"the, cases, and, huanan, seafood, market, of, a, to"
36066,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.102272727,"the, only, that, researchers, of, with, a, but, not"
36067,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.102272727,"that, from, in, the, market, a, animals, and, further"
36068,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.102272727,"bats, are, the, they, as, of, and, viruses, other"
36069,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.102272727,"that, the, of, in, close, to, with, a, and"
36070,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.102272727,"this, is, and, bat, to, the, viruses, that, in"
36071,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.102272727,"in, the, of, is, to, that, new, which, virus"
36072,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.102272727,"the, viruses, to, are, closely, related, by, of, sars-cov-2"
36073,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.102272727,"that, the, from, a, market, animals, in, and, further"
36074,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.102272727,"that, the, of, and, suggests, this, from, viruses, bats"
36075,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.102272727,"the, animal, reservoir, market, was, likely, that, in, and"
36076,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.102272727,"the, were, likely, to, that, virus, in, animals, and"
36077,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.102272727,"a, of, researchers, the, with, that, not, but, only"
36078,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.102272727,"a, the, huanan, seafood, and, market, of, cases, to"
36079,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.102272727,"its, that, it, to, as, the, of, is, for"
36080,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.102272727,"such, been, by, and, in, to, the, of, has"
36081,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.102272727,"the, by, of, to, such, and, in, has, been"
36082,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.102272727,"this, suggests, that, from, bats, the, and, of, viruses"
36083,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.102272727,"and, the, bat, to, viruses, that, this, in, is"
36084,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.102272727,"the, of, to, new, that, in, which, virus, is"
36085,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.102272727,"sars-cov-2, origin, of, for, to, a, novel, that, in"
36086,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.102040816,"are, numerous, and, viruses, other"
36087,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.102040816,"in, to, sars-cov-2, pangolin, which"
36088,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.102040816,"humans, from, and, the, of"
36089,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.102040816,"the, virus, and, humans, of"
36090,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.102040816,"that, and, virus, for, of"
36091,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.102040816,"of, more, than, and, bats"
36092,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.102040816,"to, of, and, sars-cov, which"
36093,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.102040816,"to, of, and, in, bats"
36094,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.102040816,"the, genetic, to, sequences, viruses,"
36095,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.102040816,"to, the, sars-, and, sars-cov"
36096,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.102040816,"sars-cov, and, to, of, which"
36097,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.102040816,"origin, that, been, by, be"
36098,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.102040816,"the, viruses,, genetic, sequences, to"
36099,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.102040816,"sequences, of, sars-cov-2, from, closest"
36100,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.102040816,"have, that, the, of, including"
36101,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.102040816,"a, in, the, that, was"
36102,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.102040816,"the, is, by, from, in"
36103,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.102040816,"the, bat, of, these, and"
36104,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.102040816,"as, that, natural, to, the"
36105,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.102040816,"genome, sars-cov-2, with, the, bat"
36106,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.102040816,"have, to, the, sars-cov-2, natural"
36107,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.102040816,"bat, have, the, sars-cov-2, with"
36108,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.102040816,"the, was, a, to, of"
36109,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.102040816,"to, the, a, of, sequence, that, identical, genome, identity, found"
36110,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.102040816,"of, virus, has, been, and"
36111,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.102040816,"a, variety, of, and, the"
36112,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.102040816,"of, showed, more, and, in"
36113,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.102040816,"of, patients, with, between, and"
36114,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.102040816,"between, sars-cov-2, and, with, of"
36115,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.102040816,"of, the, with, sars-like, bat"
36116,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.102040816,"to, the, of, sars-cov-2, humans"
36117,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.102040816,"and, that, origin, of, the"
36118,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.102040816,"that, the, in, bats, a"
36119,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.102040816,"and, are, numerous, other, viruses"
36120,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.102040816,"and, they, have, the, of"
36121,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.102040816,"the, after, of, and, been"
36122,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.102040816,"the, known, and, of, zoonotic"
36123,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.102040816,"are, known, zoonotic, and, the"
36124,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.102040816,"the, of, are, more, than"
36125,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.102040816,"is, and, bats,, that, to"
36126,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.102040816,"to, a, in, and, human"
36127,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.102040816,"virus, in, is, the, sequence"
36128,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.102040816,"in, of, the, as, intermediate"
36129,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.102040816,"the, of, to, humans, sars-cov-2"
36130,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.102040816,"the, of, that, number, is"
36131,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.102040816,"the, of, coronavirus, to, and"
36132,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.102040816,"of, the, a, to, animal"
36133,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.102040816,"and, most, been, the, of"
36134,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.102040816,"and, the, of, be, natural"
36135,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.102040816,"that, to, as, the, natural"
36136,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.102040816,"to, palm, as, civets, from, for, the, virus, and, species"
36137,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.102040816,"the, covid-19, of, identity, with"
36138,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.102040816,"to, at, the, which, is"
36139,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.102040816,"from, in, wuhan, the, previously"
36140,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.102040816,"sars-cov-2, from, to, a, high"
36141,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.102040816,"the, sequence, coronavirus, from, to"
36142,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.102040816,"the, is, coronavirus, a, sequence"
36143,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.102040816,"the, of, which, to, and"
36144,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.102040816,"and, to, other, the, in"
36145,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.102040816,"coronavirus, and, from, animals, to"
36146,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.102040816,"the, in, to, coronaviruses, from"
36147,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.102040816,"health, for, and, to, the"
36148,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.102040816,"for, and, that, in, the"
36149,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.102040816,"and, be, sars-cov-2, to, the"
36150,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.102040816,"bats, pangolins, the, from, in"
36151,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.102040816,"of, to, from, found, in"
36152,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.102040816,"in, a, and, that, the"
36153,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.102040816,"hypothesis, the, that, been, by"
36154,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.102040816,"to, high, a, from, sars-cov-2"
36155,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.102040816,"found, high, to, sars-cov-2, in"
36156,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.102040816,"genetic, similarity, sars-cov-2, coronaviruses, to"
36157,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.102040816,"through, have, that, the, and"
36158,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.102040816,"the, they, have, of, and"
36159,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.102040816,"coronavirus, and, the, of, from"
36160,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.102040816,"and, bat, ratg13, the, that"
36161,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.102040816,"the, of, that, sars-cov-2, result"
36162,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.102040816,"and, to, of, the, huanan"
36163,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.102040816,"that, in, of, with, sars-cov-2"
36164,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.102040816,"sars-cov-2, and, in, animal, humans"
36165,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.102040816,"a, to, in, the, huanan"
36166,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.102040816,"are, to, the, in, that"
36167,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.102040816,"a, the, of, virus, from"
36168,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.102040816,"been, and, the, of, most"
36169,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.102040816,"and, from, the, coronavirus, of"
36170,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.102040816,"the, of, and, coronavirus, from"
36171,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.102040816,"of, the, and, other, coronavirus"
36172,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.102040816,"the, of, from, and, in"
36173,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.102040816,"the, of, been, in, animal"
36174,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.102040816,"the, human, to, these, viruses"
36175,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.102040816,"sars-cov-2, the, and, in, that"
36176,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.102040816,"of, were, in, to, and"
36177,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.102040816,"sars-cov-2, into, humans, on, to"
36178,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.102040816,"on, from, in, of, and"
36179,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.102040816,"in, of, to, sars-cov-2, at"
36180,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.102040816,"the, of, a, as, and"
36181,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.102040816,"all, sars-cov-2, the, in, that"
36182,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.102040816,"was, that, the, and, to"
36183,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.102040816,"the, and, of, to, that"
36184,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.102040816,"sars-cov-2, the, and, from, animal"
36185,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.102040816,"also, from, in, the, of"
36186,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.102040816,"the, that, sars-, cov-2, from"
36187,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.102040816,"the, of, to, human, is, natural, a, that, this, evidence"
36188,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.102040816,"of, evidence, that, the, is, a, receptor, animal, as, for"
36189,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.102040816,"that, 2, been, by, a, of, one, to, the, for"
36190,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.102040816,"is, that, sars-cov-2, and, from"
36191,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.102040816,"is, to, sars-cov-2, known, in"
36192,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.102040816,"the, of, and, have, that, sars-cov-2, is, was, to, by"
36193,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.102040816,"is, and, bats,, it, more, that, of, sars-cov-2, to, by"
36194,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.102040816,"to, and, of, bats,, it, is, that, viruses, related, in"
36195,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.102040816,"that, sars-cov-2, could, be, the"
36196,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.102040816,"on, the, by, that, sars-cov-2"
36197,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.102040816,"that, sars-cov-2, the, with, at"
36198,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.102040816,"in, humans, it, that, the"
36199,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.102040816,"in, the, to, that, mutations"
36200,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.102040816,"is, an, a, in, from"
36201,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.102040816,"we, the, was, to, a"
36202,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.102040816,"the, that, an, at, of"
36203,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.102040816,"and, virus, with, the, was"
36204,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.102040816,"with, the, as, a, and"
36205,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.102040816,"to, the, has, and, as"
36206,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.102040816,"that, the, seafood, animals, were"
36207,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.102040816,"a, zoonotic, to, of, and"
36208,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.102040816,"all, and, coronaviruses, that, of"
36209,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.102040816,"a, of, to, that, zoonotic"
36210,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.102040816,"coronavirus, from, animals, to, and"
36211,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.102040816,"a, the, coronavirus, bat, that"
36212,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.102040816,"to, the, genome, and, that"
36213,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.102040816,"to, the, of, as, pangolins."
36214,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.102040816,"were, of, in, and, to"
36215,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.102040816,"the, that, in, with, were"
36216,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.102040816,"the, that, in, to, market"
36217,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.102040816,"the, cases, market, of, to"
36218,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.102040816,"to, in, the, or, which"
36219,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.102040816,"the, of, that, to, than"
36220,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.102040816,"to, and, the, which, is"
36221,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.102040816,"from, the, to, virus, that, 99%, and, of, coronavirus, an"
36222,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.102040816,"is, and, to, the, that"
36223,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.102040816,"from, the, of, virus, and"
36224,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.102040816,"that, the, to, a, and"
36225,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.102040816,"the, of, covid-19, identity, with"
36226,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.102040816,"has, been, the, to, have"
36227,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.102040816,"he, of, sars-cov-2, from, the"
36228,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.102040816,"the, of, suggested, that, to"
36229,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.102040816,"the, that, was, to, have, is, by, of, and, sars-cov-2"
36230,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.102040816,"to, of, which, have, sars-cov-2"
36231,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.102040816,"from, virus, to, and, the"
36232,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.102040816,"the, in, a, to, and"
36233,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.102040816,"in, the, that, a, bats"
36234,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.102040816,"that, have, through, and, the"
36235,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.102040816,"the, from, at, market, that"
36236,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.102040816,"bats, a, virus, the, china"
36237,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.102040816,"the, to, that, from, bats"
36238,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.102040816,"of, to, that, zoonotic, may"
36239,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.102040816,"is, bats, are, the, to"
36240,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.102040816,"the, of, that, was, as"
36241,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.102040816,"that, the, of, as, a"
36242,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.102040816,"of, at, the, a, that"
36243,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.102040816,"the, and, in, believe, that"
36244,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.102040816,"to, origin, the, that, and"
36245,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.102040816,"in, were, to, origin, that"
36246,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.102040816,"that, the, and, mers-cov, sars-cov"
36247,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.102040816,"the, and, to, sars-cov, sars-"
36248,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.102040816,"their, natural, and, to, the"
36249,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.102040816,"the, and, palm, civet, dromedary"
36250,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.102040816,"a, for, the, it, is"
36251,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.102040816,"for, and, field, the, of"
36252,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.102040816,"is, the, with, and, for"
36253,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.102040816,"in, the, market, from, animals"
36254,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.102040816,"the, that, could, be, sars-cov-2"
36255,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.102040816,"that, were, the, seafood, animals"
36256,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.102040816,"have, that, the, of, with"
36257,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.102040816,"that, the, from, at, market"
36258,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.102040816,"isolated, from, at, the, viral"
36259,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.102040816,"with, the, sars-like, bat, of"
36260,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.102040816,"the, bat, coronavirus, that, a"
36261,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.102040816,"a, of, viruses, reservoirs, the"
36262,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.102040816,"be, that, the, of, bat"
36263,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.102040816,"of, the, has, been, to"
36264,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.102040816,"and, that, a, the, is"
36265,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.102040816,"the, 80%, to, of, bat"
36266,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.102040816,"is, the, of, similar, to"
36267,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.102040816,"and, the, of, to, as, bats, with, for, recombination, which"
36268,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.102040816,"the, in, a, as, of"
36269,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.102040816,"the, of, a, as, viruses"
36270,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",Many of these CoVs can infect several animal species as well,0.102040816,"of, many, several, as, covs"
36271,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.102040816,"is, a, from, to, that"
36272,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.102040816,"a, for, the, is, it"
36273,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.102040816,"in, the, coronaviruses, from, to"
36274,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.102040816,"also, the, of, in, to"
36275,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.102040816,"in, the, of, isolated, from"
36276,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.102040816,"rhinolophus, are, the, and, in"
36277,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.102040816,"human, and, virus, the, in"
36278,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.102040816,"to, in, and, human, animal"
36279,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.102040816,"the, from, market, and, to"
36280,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.102040816,"the, that, from, humans, and"
36281,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.102040816,"the, from, animal, and, sars-cov-2"
36282,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.102040816,"from, humans, the, that, sars-cov-2"
36283,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.102040816,"that, sars-cov-2, from, and, is"
36284,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.102040816,"is, to, that, bats,, and"
36285,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.102040816,"that, to, more, is, by, of, bats,, it, and, sars-cov-2"
36286,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.102040816,"that, sars-cov-2, of, and, to"
36287,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.102040816,"the, that, of, and, lineage"
36288,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.102040816,"other, coronavirus, and, the, of"
36289,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.102040816,"the, virus, was, with, and"
36290,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.102040816,"the, virus, human, in, and"
36291,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.102040816,"and, the, covid-19, virus, of"
36292,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.102040816,"virus, by, and, was, the"
36293,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.102040816,"the, with, of, virus, and"
36294,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.102040816,"of, between, and, with, patients"
36295,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.102040816,"and, the, virus, from, in"
36296,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.102040816,"the, from, analysis, covid-19, and"
36297,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.102040816,"the, genome, of, from, to"
36298,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.102040816,"are, coronaviruses, to, the, and"
36299,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.102040816,"are, for, of, coronaviruses, which"
36300,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.102040816,"of, the, is, to, sars-cov-2"
36301,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.102040816,"coronaviruses, to, genomic, sars-cov-2, the"
36302,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.102040816,"to, the, sequence, coronavirus, from"
36303,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.102040816,"that, the, was, as, of"
36304,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.102040816,"from, genome, to, the, of"
36305,"�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.102040816,"sars, bat, zc45, and, the"
36306,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.102040816,"the, of, 80%, to, bat"
36307,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.102040816,"moreover,, to, the, has, and"
36308,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.102040816,"to, and, of, that, bat"
36309,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.102040816,"the, on, that, sars-cov-2, by"
36310,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.102040816,"revealed, that, sars-cov-2, from, the"
36311,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.102040816,"the, sars-cov-2, through, and, by"
36312,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.102040816,"the, from, a, and, sars-cov-2"
36313,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.102040816,"sars-cov-2, ace2, in, animal, or"
36314,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.102040816,"revealed, and, the, of, virus"
36315,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.102040816,"that, from, the, seafood, animals"
36316,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.102040816,"the, to, humans, and, spread"
36317,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.102040816,"a, in, the, that, from"
36318,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.102040816,"sars-cov-2, with, genome, bat, the"
36319,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.102040816,"of, sars-cov-2, between, and, with"
36320,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.102040816,"of, a, virus, the, from"
36321,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.102040816,"of, the, virus, revealed, and"
36322,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.102040816,"for, that, in, the, of"
36323,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.102040816,"he, from, the, of, sars-cov-2"
36324,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.102040816,"the, revealed, that, sars-cov-2, from"
36325,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.102040816,"that, the, from, seafood, animals"
36326,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.102040816,"the, that, for, part, of"
36327,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.102040816,"that, the, seafood, market,, of"
36328,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.102040816,"that, is, from, to, a"
36329,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.102040816,"of, was, to, which, the"
36330,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.102040816,"this, that, the, deep, of"
36331,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.102040816,"the, after, been, of, and"
36332,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.102040816,"it, is, that, the, and"
36333,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.102040816,"a, of, that, the, in"
36334,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.102040816,"that, was, a, the, in"
36335,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.102040816,"at, the, in, similar, to"
36336,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.102040816,"a, to, in, with, the"
36337,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.102040816,"a, of, in, the, to"
36338,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.102040816,"the, huanan, in, presentations, of, identified, chinese, and, with, an"
36339,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.102040816,"the, of, be, to, that"
36340,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.102040816,"the, of, that, a, sars-cov-2"
36341,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.102040816,"analysis, the, of, a, that"
36342,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.102040816,"at, the, in, is, to"
36343,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.102040816,"of, the, was, to, sars-cov-2"
36344,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.102040816,"was, and, to, sars-cov-2, the"
36345,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.102040816,"the, of, a, was, to"
36346,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.102040816,"the, of, horseshoe, (rhinolophus, in"
36347,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.102040816,"closest, bat, to, sars-cov-2, the"
36348,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.102040816,"an, the, of, at, that"
36349,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.102040816,"that, of, the, part, for"
36350,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.102040816,"a, in, the, that, for"
36351,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.102040816,"from, the, of, a, sars-cov-2"
36352,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.102040816,"the, of, natural, sars-cov-2, as"
36353,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.102040816,"that, the, sars-cov-2, ratg13, pangolin"
36354,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.102040816,"a, was, the, we, to"
36355,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.102040816,"of, the, as, viruses, a"
36356,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.102040816,"the, virus, bats, a, china"
36357,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.102040816,"of, are, by, a, the"
36358,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K",0.102040816,"to, in, more, with, than"
36359,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.102040816,"a, the, of, bat, and"
36360,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.102040816,"a, of, the, has, been"
36361,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.102040816,"the, as, a, with, and"
36362,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.102040816,"as, the, of, a, because"
36363,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.102040816,"the, covs, for, a, from"
36364,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.102040816,"a, in, with, sars-cov-2, the"
36365,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.102040816,"the, of, as, a, because"
36366,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.102040816,"of, bat, a, possible, the"
36367,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.102040816,"the, of, is, similar, to"
36368,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.102040816,"is, similar, sars-cov-2, the, of"
36369,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.102040816,"and, by, virus, the, was"
36370,"Bats are the second  

largest order of mammals, with over 1,230 species.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.102040816,"bats, the, of, with, over"
36371,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.102040816,"in, the, of, sars-cov-2, which"
36372,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.102040816,"sars-cov-2, from, and, of, coronaviruses"
36373,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.102040816,"of, with, that, sars-cov-2, in"
36374,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.102040816,"that, to, is, sars-cov-2, the"
36375,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.102040816,"the, not, that, of, is"
36376,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.102040816,"a, of, origin, that, zoonotic"
36377,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.102040816,"sars-cov-2, to, high, found, in"
36378,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.102040816,"the, as, has, and, to"
36379,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.102040816,"moreover,, and, the, has, to"
36380,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.102040816,"the, sars-cov-2, has, and, to"
36381,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","bats are also important reservoir species for a great 

range of coronaviruses",0.102040816,"a, of, also, reservoir, species"
36382,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","bats are also important reservoir species for a great 

range of coronaviruses",0.102040816,"also, a, coronaviruses, are, of"
36383,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.102040816,"in, study,, of, and, to"
36384,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.102040816,"in, the, similar, to, at"
36385,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.102040816,"be, the, natural, of, and"
36386,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.102040816,"the, to, hace2, sars-cov-2, and"
36387,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.102040816,"in, the, of, as, intermediate"
36388,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.102040816,"that, or, species, of, the"
36389,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.102040816,"that, the, sars-cov-2, a, or"
36390,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.102040816,"the, sars-cov-2, and, be, to"
36391,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.102040816,"in, and, be, to, humans"
36392,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.102040816,"the, has, been, to, have"
36393,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.102040816,"are, in, and, to, through"
36394,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.102040816,"the, by, sars-cov-2, through, and"
36395,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.102040816,"the, of, to, by, is"
36396,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.102040816,"species, and, humans, by, the"
36397,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.102040816,"the, to, was, of, a"
36398,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.102040816,"in, the, to, at, and"
36399,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.102040816,"sars-cov-2, the, of, that, from"
36400,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.102040816,"of, are, coronaviruses, which, for"
36401,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.102040816,"the, of, in, to, a"
36402,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.102040816,"in, is, the, covid-19, sars-cov-2"
36403,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.102040816,"the, in, of, horseshoe, (rhinolophus"
36404,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Bats are the second  

largest order of mammals, with over 1,230 species.",0.102040816,"of, bats, with, over, the"
36405,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.102040816,"the, sars-cov-2, which, of, coronaviruses"
36406,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.102040816,"the, to, bat, and, sars-cov-2"
36407,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.102040816,"the, and, that, sars-cov-2, to"
36408,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.102040816,"to, in, the, bat, and"
36409,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.102040816,"are, a, of, by, the"
36410,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.102040816,"the, of, possible, a, bat"
36411,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.102040816,"bats, as, the, recombination, to, which, with, of, for, and"
36412,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.102040816,"of, have, sars-cov-2, which, to"
36413,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.102040816,"from, a, to, of, with"
36414,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.102040816,"the, closest, to, sars-cov-2, bat"
36415,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.102040816,"to, the, which, coronavirus, bat, similarity, at, whole, genome, related"
36416,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.102040816,"similarity, to, genome, which, bat"
36417,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.102040816,"the, of, sars-cov-2, spike, to"
36418,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.102040816,"that, the, with, have, of"
36419,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.102040816,"from, in, also, the, of"
36420,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.102040816,"in, the, spike, is, of"
36421,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.102040816,"the, which, is, to, and"
36422,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.102040816,"the, is, to, a, and"
36423,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.102040816,"at, a, and, the, to"
36424,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.102040816,"the, of, for, sars-cov-2, and"
36425,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.102040816,"and, of, sars-cov-2, the, for"
36426,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.102040816,"human, animal, in, to, and"
36427,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.102040816,"the, of, to, is, by"
36428,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.102040816,"after, the, of, as, virus, to, by, is, closely, related"
36429,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.102040816,"sars-cov-2, to, is, known, in"
36430,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.102040816,"to, sars-cov-2, in, the, is"
36431,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.102040816,"coronaviruses, are, to, the, and"
36432,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.102040816,"the, genomic, sars-cov-2, to, coronaviruses"
36433,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.102040816,"a, in, the, with, to"
36434,"In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.102040816,"in, to, with, more, than"
36435,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.102040816,"the, that, in, it, humans"
36436,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.102040816,"the, is, that, and, it"
36437,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.102040816,"the, covid-19, is, sars-cov-2, in"
36438,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.102040816,"that, the, and, is, be"
36439,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.102040816,"was, the, of, to, a"
36440,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.102040816,"a, the, to, and, was"
36441,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.102040816,"the, from, market, to, and"
36442,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.102040816,"the, of, to, was, from"
36443,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.102040816,"after, the, of, closely, related, virus, to, as, by, is"
36444,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.102040816,"species, and, was, found, in, by, closely, related, the, palm"
36445,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.102040816,"found, that, the, genome, sequence, of, identical, to, a, identity"
36446,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.102040816,"related, bat, coronavirus, to, similarity, which, at, the, whole, genome"
36447,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.102040816,"the, virus, an, to, 99%, that, of, and, coronavirus, from"
36448,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.102040816,"the, of, at, this, time, that, a, virus, in, for"
36449,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.102040816,"from, as, virus, to, for, and, the, species, palm, civets"
36450,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.102040816,"in, the, of, chinese, and, identified, an, with, presentations, huanan"
36451,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.102040816,"the, huanan, to, and, of"
36452,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.102040816,"in, a, the, to, huanan"
36453,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.102040816,"the, known, of, and, zoonotic"
36454,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.102040816,"of, cases, to, the, market"
36455,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.102040816,"is, a, natural, to, the"
36456,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.102040816,"the, origin, of, between, and"
36457,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.102040816,"are, the, known, and, zoonotic"
36458,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.102040816,"this, to, the, in, that"
36459,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.102040816,"to, and, a, at, the"
36460,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.102040816,"in, the, to, at, that"
36461,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.102040816,"sars-cov-2, into, humans, to, on"
36462,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.102040816,"the, that, a, to, humans"
36463,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.102040816,"the, virus, is, to, that"
36464,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.102040816,"the, is, a, natural, to"
36465,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.102040816,"the, that, virus, found, with"
36466,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.102040816,"the, natural, is, with, to"
36467,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.102040816,"coronaviruses, from, pangolins, and, sars-cov-2"
36468,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.102040816,"sars-cov-2, in, pangolins, from, and"
36469,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.102040816,"to, the, and, their, natural"
36470,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.102040816,"a, of, the, viruses, reservoirs"
36471,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.102040816,"animal, and, sars-cov-2, humans, in"
36472,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.102040816,"that, the, virus, in, a"
36473,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.102040816,"that, to, human, this, the, a, of, is, evidence, natural"
36474,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.102040816,"the, to, sars-cov-2, of, spike"
36475,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.102040816,"the, sars-cov-2, this, or, of"
36476,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.102040816,"from, sars-, cov-2, the, that"
36477,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.102040816,"it, is, that, a, the"
36478,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.102040816,"human, that, a, the, is"
36479,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.102040816,"a, that, the, to, which"
36480,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.102040816,"is, in, the, of, spike"
36481,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.102040816,"is, the, similarity, for, sars-cov-2"
36482,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.102040816,"the, of, can, that, and"
36483,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.102040816,"a, is, the, that, it"
36484,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.102040816,"the, sars-cov-2, and, from, a"
36485,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.102040816,"coronaviruses, sars-cov-2, and, pangolins, from"
36486,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.102040816,"all, coronaviruses, that, of, and"
36487,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.102040816,"the, believe, that, in, and"
36488,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.102040816,"the, that, of, not, is"
36489,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.102040816,"of, that, is, the, and"
36490,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.102040816,"of, in, coronaviruses, including, sars-cov-2"
36491,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.102040816,"genome, a, the, of, bat"
36492,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.102040816,"the, in, that, this, virus"
36493,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.102040816,"and, showed, of, in, more"
36494,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.102040816,"analysis, the, covid-19, from, and"
36495,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.102040816,"to, the, that, from, and"
36496,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.102040816,"the, of, that, is, bat"
36497,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.102040816,"receptor, that, as, the, animal, a, of, is, evidence, for"
36498,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.102040816,"and, of, the, virus, humans"
36499,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.102040816,"that, of, the, seafood, market,"
36500,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.102040816,"covid-19, in, the, that, originated"
36501,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.102040816,"that, the, of, to, intermediate"
36502,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.102040816,"and, be, to, humans, in"
36503,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.102040816,"in, and, are, to, through"
36504,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.102040816,"the, that, of, cases, in"
36505,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.102040816,"in, the, rhinolophus, are, and"
36506,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.102040816,"that, the, were, in, with"
36507,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.102040816,"virus, that, found, with, the"
36508,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.102040816,"in, the, that, which, virus"
36509,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.102040816,"that, the, animals, in, to"
36510,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.102040816,"of, species, that, the, or"
36511,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.102040816,"is, from, by, the, in"
36512,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.102040816,"the, in, from, is, by"
36513,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.102040816,"and, in, to, bats, of"
36514,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.102040816,"the, species, humans, and, by"
36515,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.102040816,"in, the, found, palm, was, species, by, closely, related, and"
36516,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.102040816,"found, the, an, intermediate, host"
36517,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.102040816,"are, in, to, virus, bats"
36518,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.102040816,"bats, are, of, and, several, which, to, in, such, as"
36519,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.102040816,"a, was, the, of, and"
36520,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.102040816,"in, a, of, and, the"
36521,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.102040816,"sars-cov-2, in, and, pangolins, from"
36522,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.102040816,"origin, of, sars-cov-2, the, in"
36523,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.102040816,"the, sequence, of, sars-cov-2, is"
36524,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.102040816,"is, the, in, sequence, virus"
36525,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.102040816,"the, isolated, from, at, viral"
36526,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.102040816,"is, the, of, similar, sars-cov-2"
36527,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.102040816,"the, from, bats, pangolins, in"
36528,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.102040816,"that, the, of, covid-19, a"
36529,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.102040816,"the, to, from, animals, a"
36530,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.102040816,"the, a, for, covs, from"
36531,"bats are also important reservoir species for a great 

range of coronaviruses","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.102040816,"also, reservoir, species, a, of"
36532,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.102040816,"has, been, that, species, humans"
36533,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.102040816,"such, that, likely, to, from"
36534,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.102040816,"sars-cov-2, and, bat, cov, that"
36535,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.102040816,"the, to, and, for, health"
36536,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.102040816,"field, for, the, of, and"
36537,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.102040816,"to, the, of, and, for"
36538,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.102040816,"to, it, that, in, bat"
36539,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.102040816,"the, number, of, that, is"
36540,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.102040816,"the, has, a, of, that"
36541,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.102040816,"has, been, species, that, humans"
36542,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.102040816,"genome, was, the, to, found"
36543,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.102040816,"the, origin, of, that, and"
36544,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.102040816,"a, is, the, that, human"
36545,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.102040816,"the, natural, of, sars-cov-2, as"
36546,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.102040816,"for, that, the, of, sars-cov-2"
36547,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.102040816,"has, a, and, the, of"
36548,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.102040816,"hypothesis, origin, the, has, and"
36549,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.102040816,"have, sars-cov-2, to, the, natural"
36550,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.102040816,"is, in, from, a, an"
36551,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.102040816,"sars-cov-2, and, from, to, that"
36552,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.102040816,"be, that, origin, been, by"
36553,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.102040816,"hypothesis, that, the, been, by"
36554,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.102040816,"that, is, to, the, and"
36555,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.102040816,"the, hypothesis, origin, has, and"
36556,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.102040816,"sars-cov-2, to, genetic, similarity, coronaviruses"
36557,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.102040816,"sars-cov-2, of, sequences, from, closest"
36558,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.102040816,"the, of, which, was, to"
36559,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.102040816,"to, of, which, in, the"
36560,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.102040816,"the, sequence, a, coronavirus, is"
36561,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.102040816,"this, of, to, the, that"
36562,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.102040816,"bat, coronavirus, to, sars-cov-2, the"
36563,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.102040816,"to, a, obtained, from, bat"
36564,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.102040816,"the, genome, was, found, to"
36565,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.102040816,"are, to, is, the, bats"
36566,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.102040816,"a, to, the, which, that"
36567,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.102040816,"of, covs, and, which, to"
36568,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.102040816,"of, the, sars-cov-2, in, origin"
36569,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.102040816,"at, bat, the, sars-cov-2, probable"
36570,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.102040816,"sars-cov-2, the, complete, origin, of"
36571,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.102040816,"to, from, in, of, found"
36572,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.102040816,"bat, to, similarity, which, genome"
36573,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.102040816,"obtained, from, to, a, bat"
36574,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.102040816,"in, study,, of, to, and"
36575,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.102040816,"of, to, which, covs, and"
36576,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.102040816,"of, two, in, and, sequences"
36577,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.102040816,"2, that, to, one, the, by, a, of, been, for"
36578,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.102040816,"the, sars-cov-2, and, pangolin, of"
36579,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.102040816,"a, are, for, the, and"
36580,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.102040816,"a, that, the, sars-cov-2, and"
36581,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.102040816,"the, sars-cov-2, and, of, that"
36582,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.102040816,"in, two, of, sequences, and"
36583,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.102040816,"that, of, is, sars-cov-2, the"
36584,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.102040816,"in, that, the, are, to"
36585,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.102040816,"the, genome, to, and, that"
36586,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.102040816,"in, be, that, the, and"
36587,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.102040816,"probable, bat, sars-cov-2, at, the"
36588,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.102040816,"the, is, to, that, and"
36589,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.102040816,"the, is, that, to, and"
36590,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.102040816,"the, is, sars-cov-2, to, in"
36591,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same",0.102040816,"the, bat, zc45, and, sars"
36592,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.102040816,"to, the, in, which, or"
36593,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.102040816,"this, in, the, that, sars-cov-2"
36594,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.102040816,"the, that, between, and, sars-cov-2"
36595,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.102040816,"cov, and, sars-cov-2, than, similarity"
36596,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.102040816,"the, of, pangolin, and, bat"
36597,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.102040816,"the, of, sars-cov-2, or, this"
36598,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.102040816,"of, pangolin, and, the, sars-cov-2"
36599,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.102040816,"the, that, sars-cov-2, ratg13, pangolin"
36600,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.102040816,"have, sars-cov-2, with, bat, the"
36601,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.102040816,"the, to, of, as, pangolins."
36602,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.102040816,"the, and, of, bat, these"
36603,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.102040816,"the, previously, in, from, wuhan"
36604,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.102040816,"of, from, in, and, on"
36605,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.102040816,"the, virus, of, and, from"
36606,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.102040816,"the, between, and, of, origin"
36607,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.102040816,"are, the, of, more, than"
36608,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.102040816,"that, and, sars-cov-2, to, with"
36609,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.102040816,"to, sars-cov-2, the, is, of"
36610,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.102040816,"to, the, of, and, sars-cov-2"
36611,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.102040816,"sars-cov-2, of, and, the, with"
36612,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.102040816,"in, the, that, and, for"
36613,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.102040816,"in, the, and, of, sars-cov-2"
36614,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.102040816,"in, the, of, that, for"
36615,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.102040816,"the, that, of, sars-cov-2, for"
36616,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.102040816,"the, of, that, have, including"
36617,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.102040816,"a, of, the, that, bats"
36618,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.102040816,"similarity, sars-cov-2, and, cov, than"
36619,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.102040816,"for, the, is, and, with"
36620,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.102040816,"similarity, sars-cov-2, the, for, is"
36621,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.102040816,"the, with, sars-cov-2, is, for"
36622,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.102040816,"and, the, to, hace2, sars-cov-2"
36623,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.102040816,"in, are, to, sars-cov-2, and"
36624,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.102040816,"of, and, that, for, virus"
36625,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.102040816,"the, of, and, that, in"
36626,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.102040816,"in, of, the, virus, and"
36627,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.102040816,"and, that, of, sars-cov-2, to"
36628,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.102040816,"and, virus, with, the, of"
36629,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.102040816,"of, be, the, bat, that"
36630,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.102040816,"the, of, deep, that, this"
36631,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.102040816,"the, in, and, that, be"
36632,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.102040816,"that, the, bats, to, from"
36633,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.102040816,"the, was, from, to, of"
36634,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.102040816,"sars-cov-2, to, pangolin, in, which"
36635,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.102040816,"at, of, sars-cov-2, in, to"
36636,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.102040816,"the, mutations, that, in, to"
36637,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.102040816,"at, in, the, that, to"
36638,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.102040816,"the, that, virus, in, which"
36639,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.102040816,"origin, of, sars-cov-2, complete, the"
36640,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.102040816,"to, recombination, the, of, virus"
36641,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.102040816,"to, the, virus, of, recombination"
36642,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.102040816,"pangolin-cov, with, the, of, to"
36643,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.102040816,"that, likely, from, to, such"
36644,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.102040816,"a, the, sars-cov-2, and, an"
36645,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.102040816,"and, be, sars-cov-2, the, between"
36646,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.102040816,"in, been, the, of, animal"
36647,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.102040816,"the, for, time, a, virus, that, this, in, of, at"
36648,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.102040816,"that, the, from, a, in"
36649,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.102040816,"the, in, that, for, a"
36650,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.102040816,"that, the, covid-19, originated, in"
36651,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.102040816,"is, natural, with, to, the"
36652,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.102040816,"sars-cov-2, including, in, coronaviruses, of"
36653,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.102040816,"a, and, are, the, for"
36654,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.102040816,"a, zoonotic, that, of, to"
36655,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.102040816,"may, of, to, that, zoonotic"
36656,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.102040816,"origin, were, to, that, in"
36657,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.102040816,"that, of, zoonotic, origin, a"
36658,Many of these CoVs can infect several animal species as well,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.102040816,"many, of, covs, several, as"
36659,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.102040816,"bats, which, several, of, are, to, such, as, and, in"
36660,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.102040816,"that, sars-cov-2, was, the, in"
36661,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.102040816,"was, that, the, in, of"
36662,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.102040816,"of, sars-cov-2, in, the, to"
36663,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.102040816,"to, a, of, animal, the"
36664,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.102040816,"the, of, its, be, to"
36665,"bats are also important reservoir species for a great 

range of coronaviruses","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.102040816,"are, also, a, of, coronaviruses"
36666,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.102040816,"viruses, that, to, related, in, is, of, bats,, it, and"
36667,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.102040816,"and, that, to, of, bat"
36668,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.102040816,"that, bat, to, it, in"
36669,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.102040816,"of, coronaviruses, from, and, sars-cov-2"
36670,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.102040816,"that, the, to, intermediate, of"
36671,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.102040816,"an, intermediate, host, found, the"
36672,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.102040816,"to, the, of, pangolin-cov, with"
36673,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.102040816,"sars-cov-2, the, of, to, coronaviruses"
36674,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.102040816,"that, a, the, sars-cov-2, is"
36675,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.102040816,"sars-cov-2, a, that, the, or"
36676,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.101851852,"by, was, at, in, that, the, is, closely, related, to, of"
36677,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.101851852,"the, sars, of, from, that, as, was, to, coronavirus, related, and"
36678,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.101851852,"the, of, coronavirus, that, from, was, to, as, and, related, sars"
36679,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.101851852,"of, that, the, a, high, from, species, as, or, for, infections"
36680,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.101851852,"a, of, the, chinese, also, by, that, or, scientific, to, virus"
36681,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.101851852,"the, as, for, infections, a, of, species, from, high, that, or"
36682,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.101851852,"the, guangdong, pangolins, from, on, in, with, of, seized, at, virus"
36683,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.101851852,"virus, from, pangolins, seized, in, guangdong, at, with, the, of, on"
36684,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.101851852,"by, the, of, a, to, that, or, virus, also, scientific, chinese"
36685,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.101851852,"the, that, was, to, closely, related, in, is, by, of, at"
36686,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.101694915,"the, and, of, sarbecovirus, new, that"
36687,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.101694915,"from, a, sars-cov-2,, in, the, that"
36688,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.101694915,"bat, viral, sars-cov-2, and, genetic, sars-cov"
36689,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.101694915,"that, virus, bats, and, infected, animals"
36690,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.101694915,"of, coronavirus, more, than, for, study"
36691,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.101694915,"sars-cov-2, of, and, to, in, many"
36692,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.101694915,"the, of, and, have, which, to"
36693,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.101694915,"have, the, virus, and, to, from"
36694,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.101694915,"the, of, to, human, bat, sars-cov"
36695,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.101694915,"human, and, virus, with, the, of"
36696,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.101694915,"a, is, to, in, the, it"
36697,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.101694915,"have, been, to, the, of, sars-cov-2"
36698,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.101694915,"to, and, the, spike, of, sars-cov-2"
36699,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.101694915,"sars-cov-2, is, to, bat, be, the"
36700,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.101694915,"the, of, to, genetic, is, bat"
36701,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.101694915,"coronaviruses, to, sars-cov-2, found, in, and"
36702,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.101694915,"a, bat, of, sars-cov-2, the, in"
36703,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.101694915,"a, of, to, and, are, the"
36704,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.101694915,"the, a, to, that, bat, of"
36705,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.101694915,"a, of, the, and, are, viruses"
36706,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.101694915,"that, the, bat, covid-19, same, to"
36707,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.101694915,"of, that, receptor, species,, as, intermediate"
36708,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.101694915,"that, of, pangolin, similar, and, intermediate"
36709,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.101694915,"and, of, between, sars-cov-2, the, to"
36710,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.101694915,"that, of, bats, a, in, the"
36711,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.101694915,"the, of, that, in, a, human"
36712,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.101694915,"a, in, that, the, of, bats"
36713,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.101694915,"the, has, a, in, that, of"
36714,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.101694915,"are, other, and, any, known, viruses"
36715,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.101694915,"other, as, the, of, and, they"
36716,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.101694915,"of, the, been, are, other, have"
36717,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.101694915,"that, the, and, also, virus, is"
36718,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.101694915,"a, host, for, with, the, in"
36719,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.101694915,"that, the, of, with, to, ace2"
36720,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.101694915,"that, to, is, a, in, the"
36721,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.101694915,"the, and, a, in, to, that"
36722,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.101694915,"to, the, and, that, hosts, for"
36723,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.101694915,"of, covid-19, with, early, the, only"
36724,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.101694915,"the, and, to, sars-cov-2, of, are"
36725,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.101694915,"the, of, sars-cov-2, evidence, is, to"
36726,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.101694915,"sars-cov-2, have, been, in, from, and"
36727,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.101694915,"found, have, to, as, an, host"
36728,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.101694915,"nucleotide, bat, that, the, of, and"
36729,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.101694915,"studies, that, the, of, and, at"
36730,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.101694915,"sars-cov-2, a, from, bat, to, that"
36731,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.101694915,"viruses, to, the, of, that, a"
36732,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.101694915,"the, progenitor, and, viruses, were, in"
36733,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.101694915,"to, sars-cov-2, of, the, and, that"
36734,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.101694915,"humans, and, that, of, sars-cov-2, animal"
36735,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.101694915,"in, at, with, sars-cov-2, the, of"
36736,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.101694915,"a, of, in, the, and, with"
36737,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.101694915,"the, of, in, and, this, a"
36738,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.101694915,"in, the, from, animal, and, of"
36739,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.101694915,"and, in, the, of, from, animal"
36740,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.101694915,"from, in, the, of, and, those"
36741,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.101694915,"of, cases, to, the, in, that"
36742,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.101694915,"sars-cov-2, a, that, humans, to, the"
36743,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.101694915,"are, known, and, viruses, any, other"
36744,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.101694915,"the, that, cases, with, collected, at"
36745,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.101694915,"to, the, evidence, animals, market, that"
36746,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.101694915,"evidence, to, from, a, in, that"
36747,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.101694915,"the, of, that, to, is, likely"
36748,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.101694915,"the, sars-cov-2, to, evidence, of, is"
36749,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.101694915,"the, of, that, an, scientists, is"
36750,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.101694915,"evidence, the, that, to, animals, market"
36751,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.101694915,"to, that, the, of, evidence, yet"
36752,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.101694915,"the, of, evidence, at, that, for"
36753,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.101694915,"the, and, bat, that, a, to"
36754,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.101694915,"that, to, a, coronavirus, with, the"
36755,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.101694915,"a, was, that, the, virus, to"
36756,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.101694915,"also, the, is, virus, and, that"
36757,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.101694915,"of, and, a, to, zoonotic, that"
36758,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.101694915,"affect, have, and, from, different, animals"
36759,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.101694915,"the, of, cases, and, in, to"
36760,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.101694915,"a, the, of, high, and, with"
36761,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.101694915,"in, the, of, a, that, were"
36762,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.101694915,"cases, in, the, of, that, to"
36763,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.101694915,"to, in, the, this, that, of"
36764,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.101694915,"the, they, as, of, and, other"
36765,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.101694915,"the, of, cases, in, to, and"
36766,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.101694915,"that, the, sars-cov-2, and, as, a"
36767,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.101694915,"the, of, and, that, which, to"
36768,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.101694915,"and, virus, with, the, covid-19, of"
36769,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.101694915,"the, sars-cov-2, spike, and, to, of"
36770,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.101694915,"the, of, intermediate, to, human, and"
36771,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.101694915,"to, have, the, of, and, which"
36772,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.101694915,"the, of, which, to, that, and"
36773,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.101694915,"animals, and, that, bats, virus, infected"
36774,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.101694915,"to, have, the, and, from, virus"
36775,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.101694915,"to, humans, through, and, in, bats"
36776,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.101694915,"in, the, that, virus, to, and"
36777,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.101694915,"the, in, of, and, outbreak, wuhan,"
36778,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.101694915,"the, bat, cov, and, into, with"
36779,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.101694915,"and, their, to, the, natural, is"
36780,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.101694915,"the, of, with, a, high, and"
36781,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.101694915,"reported, and, the, were, only, in"
36782,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.101694915,"the, sars-cov-2, to, be, is, bat"
36783,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.101694915,"a, it, was, that, the, used"
36784,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.101694915,"a, in, the, that, it, may"
36785,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.101694915,"it, was, that, the, used, a"
36786,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.101694915,"study, of, more, than, for, coronavirus"
36787,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.101694915,"to, the, of, sars-cov, bat, human"
36788,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.101694915,"to, the, with, or, cov,, which"
36789,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.101694915,"sars-cov, and, sars-cov-2, bat, viral, genetic"
36790,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.101694915,"nucleotide, and, that, the, bat, of"
36791,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.101694915,"of, the, sequence, and, with, bat"
36792,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.101694915,"the, nucleotide, of, and, with, sars-cov-2"
36793,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.101694915,"of, and, that, the, new, sarbecovirus"
36794,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.101694915,"that, virus, from, a, human, to"
36795,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.101694915,"the, in, could, human, and, to"
36796,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.101694915,"from, market, in, the, virus, to"
36797,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.101694915,"and, all, sars-cov-2, that, origin, is"
36798,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.101694915,"of, animal, and, that, sars-cov-2, humans"
36799,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.101694915,"sequence, with, bat, the, of, and"
36800,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.101694915,"with, the, of, and, virus, human"
36801,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.101694915,"the, virus, covid-19, of, with, and"
36802,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.101694915,"by, of, virus, with, and, the"
36803,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.101694915,"the, of, and, novel, coronavirus, bats"
36804,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.101694915,"coronavirus, the, of, is, that, to"
36805,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.101694915,"the, of, and, bat, that, to"
36806,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.101694915,"the, of, that, sars, and, to"
36807,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.101694915,"the, a, that, from, by, and"
36808,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.101694915,"et, al., at, that, the, is"
36809,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.101694915,"(sars-cov-2), in, and, that, a, china"
36810,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.101694915,"that, virus, from, a, in, this"
36811,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.101694915,"that, sars-cov-2, in, this, from, a"
36812,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.101694915,"that, the, of, were, in, a"
36813,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.101694915,"a, that, on, the, most, for"
36814,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.101694915,"the, of, and, that, novel, a"
36815,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.101694915,"the, a, that, bat, and, to"
36816,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.101694915,"to, a, in, ratg13, the, s"
36817,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.101694915,"a, sequence, that, the, in, bat"
36818,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.101694915,"bats, are, the, of, be, to"
36819,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.101694915,"a, that, to, and, in, sars-cov-2"
36820,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.101694915,"a, that, to, which, bat, and"
36821,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.101694915,"that, between, sars-cov-2, and, bat, is"
36822,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.101694915,"studies, and, that, the, at, of"
36823,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.101694915,"sars-cov-2, a, that, and, the, as"
36824,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.101694915,"that, and, sars-cov-2, share, a, common"
36825,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.101694915,"the, of, that, sars-cov-2, genomes, a"
36826,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.101694915,"the, of, at, that, sars-cov-2, a"
36827,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.101694915,"no, provided, to, the, evidence, of"
36828,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.101694915,"hypothesis, to, the, that, but, this"
36829,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.101694915,"in, shameli, closely, related, bats, sars-cov-2"
36830,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.101694915,"that, the, of, and, in, for"
36831,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.101694915,"of, in, been, furin, cleavage, coronaviruses"
36832,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.101694915,"found, are, to, suggesting, that, these"
36833,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.101694915,"to, sars-cov-2, of, in, the, and"
36834,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.101694915,"of, the, a, from, as, for"
36835,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.101694915,"a, for, the, in, with, host"
36836,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.101694915,"the, of, a, human, to, epidemic"
36837,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.101694915,"that, of, to, is, sars-cov-2, the"
36838,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.101694915,"wuhan, that, the, is, to, of"
36839,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.101694915,"by, genome, was, the, virus, to"
36840,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.101694915,"the, that, a, virus, in, this"
36841,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.101694915,"a, is, the, to, that, in"
36842,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.101694915,"the, a, coronavirus, that, with, to"
36843,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.101694915,"nucleotide, with, the, of, sars-cov-2, and"
36844,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.101694915,"the, of, rbd, et, al.,, sars-cov-2"
36845,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.101694915,"which, of, sars-cov-2, amino, acid, ratg13"
36846,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.101694915,"at, the, amino, acid, in, by"
36847,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.101694915,"in, by, with, sars-cov-2, at, the"
36848,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.101694915,"the, in, amino, acid, at, by"
36849,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.101694915,"from, is, to, sars-cov-2,, in, the"
36850,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.101694915,"the, s, a, in, ratg13, to"
36851,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.101694915,"the, in, a, use, human, to"
36852,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.101694915,"the, et, al.,, of, rbd, sars-cov-2"
36853,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.101694915,"and, that, natural, of, the, is"
36854,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.101694915,"is, the, to, be, rbd, of"
36855,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.101694915,"the, or, species, of, in, and"
36856,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.101694915,"intermediate, and, may, the, or, in"
36857,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.101694915,"the, that, sars-cov-2, a, also, and"
36858,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.101694915,"found, to, suggesting, that, these, are"
36859,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.101694915,"sars-cov-2, a, and, to, that, in"
36860,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.101694915,"in, the, and, were, to, market."
36861,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.101694915,"sars-cov-2, from, of, in, the, that"
36862,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.101694915,"that, evidence, in, from, a, to"
36863,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.101694915,"furin, cleavage, been, in, of, coronaviruses"
36864,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.101694915,"sars-cov-2, and, coronaviruses, to, the, of"
36865,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.101694915,"from, a, is, the, that, it"
36866,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.101694915,"in, of, species, and, the, or"
36867,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.101694915,"the, sars-cov-2, and, to, of, bat"
36868,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.101694915,"bats, the, reservoir, of, and, least"
36869,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.101694915,"the, and, in, progenitor, viruses, were"
36870,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.101694915,"the, covid-19, to, bat, that, same"
36871,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.101694915,"to, that, the, but, of, recombination"
36872,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.101694915,"the, in, sars-cov-2, with, at, by"
36873,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.101694915,"a, to, in, the, which, it"
36874,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.101694915,"the, of, with, that, to, ace2"
36875,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","This suggests that the BANAL series may be able to directly infect  

humans.",0.101694915,"the, that, this, suggests, to, humans."
36876,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.101694915,"the, to, of, genetic, is, bat"
36877,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.101694915,"in, the, sars-cov-2, closely, related, to"
36878,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.101694915,"of, the, cases, that, market,, by"
36879,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.101694915,"virus, that, from, to, a, human"
36880,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.101694915,"from, a, virus, that, in, this"
36881,"This suggests that the BANAL series may be able to directly infect  

humans.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.101694915,"this, suggests, that, the, to, humans."
36882,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.101694915,"the, to, of, intermediate, and, human"
36883,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.101694915,"in, were, to, humans, an, intermediate"
36884,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.101694915,"the, early, of, covid-19, only, with"
36885,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.101694915,"the, and, only, in, were, reported"
36886,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.101694915,"the, cases, that, with, at, collected"
36887,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.101694915,"the, first, that, in, with, of"
36888,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.101694915,"of, the, lineage, in, is, and"
36889,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.101694915,"covid-19, in, the, that, but, human"
36890,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.101694915,"one, also, that, with, the, of"
36891,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.101694915,"humans, the, that, a, sars-cov-2, to"
36892,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.101694915,"on, the, a, that, most, for"
36893,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.101694915,"sars-cov-2, and, to, found, in, coronaviruses"
36894,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.101694915,"to, a, of, in, the, and"
36895,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.101694915,"the, of, in, and, natural, a"
36896,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.101694915,"the, bat, that, a, sequence, in"
36897,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.101694915,"that, a, in, with, sars-cov-2, the"
36898,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.101694915,"a, in, shows, that, the, virus"
36899,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.101694915,"that, the, is, to, of, bats"
36900,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.101694915,"a, that, the, sars-cov-2,, from, in"
36901,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.101694915,"a, the, in, it, is, to"
36902,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.101694915,"it, that, the, in, may, a"
36903,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.101694915,"the, in, from, is, to, sars-cov-2,"
36904,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.101694915,"it, is, that, a, the, from"
36905,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.101694915,"it, in, a, which, to, the"
36906,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.101694915,"this, of, to, the, in, that"
36907,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.101694915,"the, of, it, that, sars-cov-2, is"
36908,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.101694915,"have, been, and, in, to, is"
36909,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.101694915,"is, especially, to, been, from, and"
36910,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.101694915,"in, the, virus, that, this, a"
36911,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.101694915,"in, the, of, that, a, human"
36912,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.101694915,"the, could, human, in, to, and"
36913,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.101694915,"and, that, the, to, sars, of"
36914,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.101694915,"to, the, epidemic, of, a, human"
36915,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.101694915,"to, a, in, the, use, human"
36916,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.101694915,"that, to, based, on, the, in"
36917,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.101694915,"and, which, to, that, humans,, cov,"
36918,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.101694915,"that, of, receptor, species,, intermediate, as"
36919,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.101694915,"the, of, as, a, for, from"
36920,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.101694915,"and, to, the, bats, of, intermediate"
36921,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.101694915,"in, an, intermediate, humans, were, to"
36922,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.101694915,"by, of, the, that, cases, market,"
36923,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.101694915,"a, viruses, to, that, the, of"
36924,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.101694915,"in, wuhan,, the, outbreak, and, of"
36925,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.101694915,"(sars-cov-2), that, and, in, a, china"
36926,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.101694915,"the, in, of, similar, to, that"
36927,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.101694915,"the, bats, reservoir, of, least, and"
36928,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.101694915,"that, the, of, and, viruses, bats"
36929,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.101694915,"the, that, of, first, with, in"
36930,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.101694915,"through, in, bats, and, to, humans"
36931,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.101694915,"not, from, a, bat, to, wildlife"
36932,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.101694915,"sars-cov-2, have, been, from, and, in"
36933,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.101694915,"the, is, of, and, lineage, in"
36934,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.101694915,"the, of, with, sars-cov-2, at, in"
36935,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.101694915,"may, in, and, the, or, intermediate"
36936,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.101694915,"a, of, the, that, covid-19, and"
36937,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.101694915,"affect, have, different, animals, and, from"
36938,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.101694915,"the, by, that, and, from, a"
36939,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.101694915,"that, has, the, of, and, to"
36940,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.101694915,"to, the, of, from, by, a"
36941,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.101694915,"that, sars-cov-2, and, share, a, common"
36942,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.101694915,"are, the, have, been, of, other"
36943,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.101694915,"the, of, to, at, that, virus"
36944,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.101694915,"a, from, bat, to, not, wildlife"
36945,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.101694915,"a, in, to, that, bat, not"
36946,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.101694915,"scientists, that, the, of, is, an"
36947,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.101694915,"this, that, sars-cov-2, may, have, in"
36948,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.101694915,"and, the, of, that, is, natural"
36949,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.101694915,"sars-cov-2, the, of, have, been, to"
36950,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.101694915,"to, the, and, their, natural, is"
36951,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.101694915,"the, of, no, evidence, provided, to"
36952,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.101694915,"is, and, to, in, have, been"
36953,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.101694915,"ratg13, of, which, amino, acid, sars-cov-2"
36954,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.101694915,"of, in, and, that, sars-cov-2, sequences"
36955,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.101694915,"in, that, bats, are, more, sars-cov-2"
36956,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.101694915,"that, sars-cov-2, and, ratg13, which, share"
36957,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.101694915,"ratg13, to, amino, acid, in, of"
36958,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.101694915,"the, that, but, to, this, hypothesis"
36959,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.101694915,"is, and, from, to, especially, been"
36960,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.101694915,"with, sars-cov-2, other, to, be, the"
36961,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.101694915,"yet, to, the, of, evidence, that"
36962,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.101694915,"that, a, the, sars-cov-2, and, to"
36963,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.101694915,"sars-cov-2, also, a, and, that, the"
36964,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.101694915,"the, virus, was, a, that, to"
36965,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.101694915,"the, virus, from, in, market, to"
36966,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.101694915,"et, al., that, the, is, at"
36967,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.101694915,"is, that, the, wuhan, of, to"
36968,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.101694915,"to, virus, by, genome, was, the"
36969,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.101694915,"a, virus, that, shows, the, in"
36970,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.101694915,"a, and, bat, to, which, that"
36971,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.101694915,"the, sars-cov-2, a, of, in, bat"
36972,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.101694915,"the, of, to, between, and, sars-cov-2"
36973,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.101694915,"in, (2020), of, and, which, to"
36974,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.101694915,"and, (2020), of, in, which, to"
36975,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.101694915,"and, are, to, of, the, a"
36976,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.101694915,"and, that, similar, of, intermediate, pangolin"
36977,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.101694915,"and, by, virus, with, the, of"
36978,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.101694915,"a, of, the, that, and, novel"
36979,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.101694915,"a, of, in, natural, and, the"
36980,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.101694915,"in, that, of, sars-cov-2, and, sequences"
36981,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.101694915,"hosts, that, to, for, and, the"
36982,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.101694915,"and, novel, the, coronavirus, bats, of"
36983,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.101694915,"that, bats, the, of, and, viruses"
36984,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same",0.101694915,"and, bat, cov, the, same, sars"
36985,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.101694915,"all, that, sars-cov-2, origin, and, is"
36986,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.101694915,"the, to, which, or, with, cov,"
36987,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.101694915,"the, in, those, that, bat, as"
36988,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.101694915,"in, bats, are, more, that, sars-cov-2"
36989,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.101694915,"share, which, that, sars-cov-2, and, ratg13"
36990,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.101694915,"sars-cov-2, is, between, and, bat, that"
36991,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.101694915,"suggest, the, probable, origin, of, and"
36992,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.101694915,"in, the, those, from, and, of"
36993,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.101694915,"suggest, the, of, and, probable, origin"
36994,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.101694915,"that, the, of, genomes, sars-cov-2, a"
36995,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.101694915,"a, of, bats, the, and, that"
36996,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.101694915,"of, natural, the, and, in, virus"
36997,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.101694915,"that, of, to, with, sars-cov-2, the"
36998,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.101694915,"the, and, has, to, that, of"
36999,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.101694915,"the, of, in, and, that, this"
37000,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.101694915,"of, the, at, that, to, virus"
37001,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.101694915,"that, the, of, recombination, but, to"
37002,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.101694915,"the, a, of, from, to, by"
37003,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.101694915,"in, the, those, that, bat, as"
37004,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.101694915,"for, the, of, evidence, at, that"
37005,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.101694915,"that, the, of, sars-cov-2, at, a"
37006,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.101694915,"the, that, human, covid-19, in, but"
37007,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.101694915,"a, zoonotic, that, of, to, and"
37008,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.101694915,"that, to, which, cov,, humans,, and"
37009,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.101694915,"closely, related, sars-cov-2, in, shameli, bats"
37010,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.101694915,"the, of, rbd, to, be, is"
37011,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.101694915,"in, to, of, amino, acid, ratg13"
37012,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.101694915,"that, not, a, bat, to, in"
37013,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.101694915,"have, an, host, to, as, found"
37014,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.101694915,"the, that, of, with, one, also"
37015,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.101694915,"and, sars-cov-2, in, to, of, many"
37016,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.101694915,"natural, in, and, the, virus, of"
37017,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.101694915,"to, sars-cov-2, of, the, and, coronaviruses"
37018,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.1015625,"an, to, a, in, for, the, virus, or, otherwise, of, and, mammals,, various"
37019,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.1015625,"this, that, infected, bats, in, the, a, and, of, come, moreover,, are, viruses"
37020,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.1015625,"of, for, various, mammals,, to, a, virus, or, otherwise, in, an, and, the"
37021,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.1015625,"and, the, of, infected, viruses, are, a, moreover,, bats, that, come, this, in"
37022,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.101449275,"the, in, bats, of, and, that, a"
37023,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.101449275,"in, a, to, human, and, closely, related"
37024,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.101449275,"of, have, and, the, to, from, humans,"
37025,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.101449275,"as, the, of, to, it, sars-cov-2, is"
37026,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.101449275,"the, is, naturally, occurring, a, in, coronaviruses"
37027,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.101449275,"sars-cov-2, is, a, sequence, from, that, in"
37028,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.101449275,"of, and, similar, in, analysis, protein, many"
37029,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.101449275,"the, that, ace2, a, virus, in, coronavirus"
37030,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.101449275,"a, in, that, had, the, to, virus"
37031,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.101449275,"in, the, was, at, from, identical, to"
37032,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.101449275,"the, was, to, at, with, for, and"
37033,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.101449275,"of, the, from, this, sars-cov-2, in, humans"
37034,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.101449275,"coronaviruses, and, a, to, could, as, host,"
37035,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.101449275,"are, reservoir, and, have, in, china, between"
37036,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.101449275,"the, of, was, at, that, from, and"
37037,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.101449275,"the, of, that, from, a, this, to"
37038,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.101449275,"the, sars-cov-2, humans, from, in, of, this"
37039,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.101449275,"that, of, humans, in, with, sars-cov-2, the"
37040,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.101449275,"the, of, a, market, virus, at, was"
37041,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.101449275,"the, animal, in, and, market, at, was"
37042,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.101449275,"the, of, in, and, virus,, a, laboratory"
37043,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.101449275,"of, to, the, that, covid-19, was, were"
37044,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.101449275,"the, of, and, were, that, earliest, to"
37045,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.101449275,"genetic, had, of, the, for, would, used"
37046,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.101449275,"the, are, to, in, of, viruses, bats,, is, most, sars, was, that, by, and"
37047,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.101449275,"of, the, covid-19, were, to, that, was"
37048,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.101449275,"that, was, first, in, were, a, market"
37049,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.101449275,"that, a, of, the, virus, is, likely"
37050,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.101449275,"of, a, analysis, that, the, virus, to"
37051,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.101449275,"this, the, in, that, are, likely, for"
37052,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.101449275,"data, on, and, that, is, most, of"
37053,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.101449275,"that, and, in, were, at, a, on"
37054,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.101449275,"results, of, the, in, and, that, a"
37055,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.101449275,"found, that, and, a, on, the, of"
37056,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.101449275,"to, the, all, clearly, that, for, of"
37057,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.101449275,"of, the, at, that, other, have, to"
37058,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.101449275,"evidence, to, that, the, of, have, for"
37059,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.101449275,"a, virus, from, bat, to, of, and"
37060,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.101449275,"of, but, and, the, to, jump, animals"
37061,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.101449275,"the, to, in, and, animals, were, virus"
37062,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.101449275,"as, the, sars-cov, with, of, for, and"
37063,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.101449275,"the, was, to, at, and, with, for"
37064,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.101449275,"for, the, sars-cov, as, of, and, with"
37065,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.101449275,"to, the, key, rbd, spike, for, of"
37066,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.101449275,"to, the, of, bats, and, as, for"
37067,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.101449275,"the, that, with, of, genetic, sars-cov-2, as"
37068,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.101449275,"the, of, is, virus, and, that, to"
37069,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.101449275,"of, and, data, on, that, is, most"
37070,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.101449275,"of, on, is, by, likely, that, genetic"
37071,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.101449275,"market, in, animal, the, or, to, virus"
37072,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.101449275,"could, to, a, as, host,, and, coronaviruses"
37073,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.101449275,"the, of, novel, coronavirus, to, as, and"
37074,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.101449275,"that, the, sars-cov-2, genomes, to, structure, of"
37075,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.101449275,"and, novel, to, the, coronavirus, of, as"
37076,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.101449275,"of, revealed, that, sars, the, to, virus"
37077,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.101449275,"in, a, that, was, first, were, market"
37078,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.101449275,"a, at, and, in, on, that, were"
37079,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.101449275,"and, at, seafood, that, was, in, a"
37080,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.101449275,"is, that, sars-cov-2, from, a, sequence, in"
37081,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.101449275,"in, is, to, that, sars-cov-2, and, a"
37082,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.101449275,"can, and, in, bats, may, between, bat"
37083,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.101449275,"that, the, of, in, was, to, a"
37084,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.101449275,"et, the, sars-cov-2, sequenced, to, of, and"
37085,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.101449275,"in, the, to, sars-cov-2, of, bat, closest"
37086,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.101449275,"sars-cov-2, is, a, and, to, that, in"
37087,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.101449275,"in, more, to, that, of, sars-cov-2, and"
37088,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.101449275,"the, of, with, that, sars-cov-2, humans, in"
37089,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.101449275,"from, and, to, the, of, sars-cov-2, in"
37090,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.101449275,"as, of, the, it, is, to, sars-cov-2"
37091,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.101449275,"it, is, that, sars-cov-2, the, result, of"
37092,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.101449275,"to, the, that, has, been, from, and"
37093,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.101449275,"the, of, it, that, sars-cov-2, is, result"
37094,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.101449275,"and, in, the, of, bats, are, likely"
37095,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.101449275,"with, the, and, for, of, a, to, that, in, this, is, where, infected, other"
37096,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.101449275,"to, related, sars-cov-2,, the, coronavirus, is, sars-cov-2"
37097,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.101449275,"on, genetic, that, is, likely, by, of"
37098,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.101449275,"the, in, of, similar, to, that, virus"
37099,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.101449275,"of, a, that, the, virus, to, sars"
37100,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.101449275,"a, the, to, that, in, had, virus"
37101,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.101449275,"the, virus, animal, in, market, or, to"
37102,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.101449275,"revealed, that, the, virus, to, sars, of"
37103,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.101449275,"the, that, with, of, virus, less, to"
37104,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.101449275,"a, to, that, the, of, from, this"
37105,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.101449275,"of, the, earliest, were, to, and, that"
37106,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.101449275,"human, and, closely, related, to, in, a"
37107,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.101449275,"identical, at, the, to, was, in, from"
37108,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.101449275,"and, that, from, the, was, at, of"
37109,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.101449275,"the, of, that, more, to, a, than"
37110,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.101449275,"the, of, at, that, a, virus, in"
37111,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.101449275,"the, viruses, that, was, to, are, most, sars, in, is, by, of, bats,, and"
37112,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.101449275,"and, the, of, infected, to, where, a, with, other, that, this, in, for, is"
37113,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.101449275,"that, are, the, of, all, and, in"
37114,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.101449275,"that, was, and, in, at, a, seafood"
37115,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.101449275,"it, that, a, of, sars-cov-2, into, the"
37116,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.101449275,"the, in, of, that, sars-cov-2, this, was"
37117,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.101449275,"of, the, in, and, that, sars-cov-2, a"
37118,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.101449275,"this, the, in, that, likely, for, sars-cov-2"
37119,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.101449275,"on, from, in, the, of, between, and"
37120,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.101449275,"that, of, to, is, a, sars-cov-2, the"
37121,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.101449275,"the, of, that, spike, a, human, to"
37122,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.101449275,"the, a, to, ace2, that, not, of"
37123,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.101449275,"the, of, used, for, would, genetic, had"
37124,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.101449275,"to, for, the, of, all, that, clearly"
37125,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.101449275,"the, key, to, spike, rbd, of, for"
37126,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.101449275,"the, it, that, of, sars-cov-2, into, a"
37127,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.101449275,"into, it, the, of, that, sars-cov-2, a"
37128,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.101449275,"the, of, in, virus, similar, to, that"
37129,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.101449275,"the, that, was, of, sars-cov-2, in, this"
37130,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.101449275,"a, coronavirus, the, virus, in, that, ace2"
37131,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.101449275,"the, of, spike, to, human, a, that"
37132,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.101449275,"the, a, ace2, that, these, bat, of"
37133,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.101449275,"a, of, and, that, the, in, bats"
37134,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.101449275,"have, reservoir, are, between, and, in, china"
37135,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.101449275,"the, that, of, are, and, in, all"
37136,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.101449275,"between, and, bat, can, may, in, bats"
37137,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.101449275,"can, be, transmission, to, bats, of, and"
37138,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.101449275,"virus, a, of, to, from, and, bat"
37139,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.101449275,"transmission, to, can, be, of, and, bats"
37140,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.101449275,"of, a, virus, at, the, market, was"
37141,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.101449275,"the, animal, at, market, was, in, and"
37142,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.101449275,"the, were, to, virus, in, animals, and"
37143,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.101449275,"to, have, the, of, and, humans,, from"
37144,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.101449275,"animals, but, jump, to, of, the, and"
37145,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.101449275,"have, a, of, one, to, and, the"
37146,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.101449275,"still, be, a, in, the, sars-cov-2, from"
37147,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.101449275,"have, to, the, of, at, other, that"
37148,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.101449275,"in, from, of, to, sars-cov-2, and, the"
37149,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.101449275,"a, of, the, likely, virus, that, is"
37150,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.101449275,"with, that, the, of, as, sars-cov-2, genetic"
37151,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.101449275,"in, of, more, to, that, sars-cov-2, and"
37152,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.101449275,"and, of, sars-cov-2, ratg13, in, which, to"
37153,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.101449275,"to, from, the, and, has, been, that"
37154,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.101449275,"the, a, is, in, coronaviruses, naturally, occurring"
37155,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.101449275,"of, the, that, structure, sars-cov-2, to, genomes"
37156,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.101449275,"sars-cov-2, sequenced, et, and, to, the, of"
37157,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.101449275,"and, from, to, that, the, coronavirus, sars-cov-2"
37158,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.101449275,"the, of, a, virus, to, sars, that"
37159,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.101449275,"in, which, to, of, sars-cov-2, and, ratg13"
37160,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.101449275,"a, of, have, and, the, to, one"
37161,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.101449275,"the, and, a, to, that, are, of"
37162,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.101449275,"the, in, a, of, virus,, and, laboratory"
37163,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.101449275,"a, the, of, and, in, results, that"
37164,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.101449275,"the, of, and, that, a, in, with"
37165,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.101449275,"and, the, that, of, sars-cov-2, in, a"
37166,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.101449275,"and, the, of, that, sars-cov-2, in, a"
37167,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.101449275,"bats, are, hosts, and, to, that, in"
37168,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.101449275,"the, closest, to, sars-cov-2, in, of, bat"
37169,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.101449275,"in, the, are, likely, that, this, for"
37170,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.101449275,"the, likely, that, for, sars-cov-2, in, this"
37171,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.101449275,"have, to, for, the, of, evidence, that"
37172,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.101449275,"bats, as, the, to, of, for, and"
37173,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.101449275,"on, in, the, and, of, from, between"
37174,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.101449275,"a, the, of, and, on, found, that"
37175,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.101449275,"the, of, and, that, a, found, to"
37176,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.101449275,"and, to, the, of, that, sars-cov-2, a"
37177,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.101449275,"the, of, a, that, to, more, than"
37178,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.101449275,"of, that, with, the, to, less, virus"
37179,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.101449275,"in, the, of, a, at, that, virus"
37180,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.101449275,"from, a, sars-cov-2, still, be, in, the"
37181,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.101449275,"are, to, in, and, that, bats, hosts"
37182,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.101449275,"the, likely, are, of, bats, in, and"
37183,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.101449275,"related, coronavirus, to, sars-cov-2,, is, sars-cov-2, the"
37184,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.101449275,"the, from, that, sars-cov-2, to, and, coronavirus"
37185,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.101449275,"the, of, to, ace2, a, that, not"
37186,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.101449275,"of, that, the, bat, a, ace2, these"
37187,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.101449275,"that, a, of, to, and, are, the"
37188,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.101449275,"protein, and, analysis, similar, of, in, many"
37189,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.101351351,"in, a, of, researchers, to, sars-related, coronaviruses, the, bats, for, and, sars, viruses, were, virus"
37190,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.101351351,"the, of, a, sars-related, viruses, in, to, sars, bats, and, were, researchers, virus, for, coronaviruses"
37191,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.101265823,"the, of, and, that, from, a, in, or"
37192,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.101265823,"and, the, that, or, of, in, from, a"
37193,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.101265823,"from, and, the, of, that, in, a, infect"
37194,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.101265823,"of, covid-19, virus, that, to, the, and, for"
37195,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.101265823,"the, of, origin, has, a, ability, human, and"
37196,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.101265823,"in, a, the, virus, that, was, is, from"
37197,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.101265823,"the, is, by, in, a, virus, that, genetic"
37198,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.101265823,"that, the, sars-cov-2, to, be, of, origin, and"
37199,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.101265823,"the, is, that, in, to, and, a, had"
37200,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.101265823,"that, a, the, of, sars-cov-2, and, pandemic, we"
37201,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.101265823,"in, the, of, an, a, from, both, and"
37202,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.101265823,"is, that, was, from, a, the, virus, in"
37203,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.101265823,"is, that, a, the, covid-19, of, virus, from"
37204,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.101265823,"it, that, the, in, animals, were, a, of"
37205,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.101265823,"it, is, that, a, the, of, virus, at"
37206,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.101265823,"a, of, the, pandemic, we, that, sars-cov-2, and"
37207,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.101265823,"and, to, that, the, of, is, likely, sars-cov-2"
37208,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.101265823,"and, with, to, the, january, on, a, was"
37209,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.101265823,"a, of, that, for, with, the, to, virus"
37210,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.101265823,"and, the, of, to, bats, that, virus, is"
37211,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.101265823,"a, the, of, in, it, animals, that, were"
37212,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.101265823,"and, an, from, to, the, market, in, animal"
37213,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.101265823,"of, the, bat, and, mers, such, as, sars"
37214,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.101265823,"of, the, and, viruses, similar, to, in, s"
37215,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.101265823,"that, the, sars-cov-2, to, in, this, hypothesis, of"
37216,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.101265823,"in, with, the, and, that, sars-cov-2, of, as"
37217,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.101265823,"and, in, to, be, that, the, hosts, sars-cov-2"
37218,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.101265823,"a, of, the, virus, that, covid-19, is, from"
37219,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.101265823,"a, at, the, of, it, virus, that, is"
37220,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.101265823,"is, that, the, virus, and, bats, of, to"
37221,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.101265823,"have, of, to, shared, with, a, all, known"
37222,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.101265823,"the, closely, related, by, in, a, similar, to"
37223,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.101265823,"is, that, a, by, the, virus, genetic, in"
37224,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.101265823,"in, by, a, closely, related, similar, to, the"
37225,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.101265823,"the, virus, for, a, of, to, with, that"
37226,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.101265823,"a, of, and, that, the, or, from, in"
37227,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.101265823,"and, a, of, in, the, for, to, human"
37228,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.101265823,"in, the, from, an, and, a, of, both"
37229,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.101265823,"a, role, of, the, at, that, to, virus"
37230,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.101265823,"to, that, the, of, and, as, more, than"
37231,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.101265823,"on, january, the, was, a, with, and, to"
37232,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.101265823,"the, from, an, animal, in, market, to, and"
37233,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.101265823,"a, is, the, to, that, in, had, and"
37234,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.101265823,"known, to, all, of, have, a, shared, with"
37235,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.101265823,"a, market, in, wuhan, the, to, of, were"
37236,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.101265823,"the, of, a, which, to, in, and, were"
37237,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.101265823,"of, covid-19, for, to, virus, that, and, the"
37238,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.101265823,"a, and, were, to, of, which, in, the"
37239,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.101265823,"the, role, of, a, at, that, virus, to"
37240,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.101265823,"a, of, and, that, the, from, in, infect"
37241,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.101265823,"and, a, of, sars-cov-2, in, the, for, to"
37242,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.101265823,"origin, of, has, human, a, and, ability, the"
37243,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.101265823,"the, origin, of, be, to, that, and, sars-cov-2"
37244,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.101265823,"this, hypothesis, in, the, of, that, sars-cov-2, to"
37245,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.101265823,"of, a, to, wuhan, the, market, were, in"
37246,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.101265823,"for, the, of, and, a, in, human, to"
37247,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.101265823,"and, to, for, the, of, sars-cov-2, in, a"
37248,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.101265823,"the, of, bat, such, as, and, sars, mers"
37249,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.101265823,"sars-cov-2, in, of, and, that, the, with, as"
37250,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.101265823,"the, of, as, that, to, and, more, than"
37251,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.101265823,"that, likely, the, of, sars-cov-2, and, is, to"
37252,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.101265823,"that, and, be, hosts, sars-cov-2, to, the, in"
37253,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.101265823,"of, the, and, to, in, ability, ace2, rbd"
37254,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.101265823,"the, of, and, s, in, viruses, similar, to"
37255,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.101265823,"the, rbd, and, in, ability, to, ace2, of"
37256,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.101123596,"a, the, of, and, in, appear, virus, that, is"
37257,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.101123596,"and, the, be, that, for, of, into, in, a"
37258,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.101123596,"and, from, in, were, that, the, of, are, sars-cov-2"
37259,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.101123596,"evidence, that, from, in, the, wet, market, a, animals"
37260,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.101123596,"a, the, of, is, virus, appear, and, in, that"
37261,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.101123596,"the, that, for, of, to, and, with, a, covid-19"
37262,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.101123596,"in, the, animal, that, virus, similar, to, is, and"
37263,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.101123596,"of, the, cases, to, were, with, huanan, seafood, market"
37264,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.101123596,"et, that, sars-cov-2, to, may, be, high, in, and"
37265,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.101123596,"the, huanan, seafood, with, market, of, cases, were, to"
37266,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.101123596,"a, for, the, of, is, virus, in, that, to"
37267,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.101123596,"the, virus, is, similar, to, and, that, in, animal"
37268,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.101123596,"evidence, the, that, in, a, from, animals, wet, market"
37269,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.101123596,"the, of, evidence, at, this, that, a, in, animal"
37270,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.101123596,"the, for, covid-19, a, of, to, with, that, and"
37271,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.101123596,"a, for, the, of, and, be, in, that, into"
37272,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.101123596,"sars-cov-2, and, be, high, et, to, that, may, in"
37273,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.101123596,"this, evidence, that, in, the, a, at, of, animal"
37274,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.101123596,"of, the, from, that, sars-cov-2, and, are, in, were"
37275,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.101010101,"had, such, as, and, to, for, the, of, in, laboratory"
37276,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.101010101,"sars-cov-2, the, and, in, related, not, that, any, of, is"
37277,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.101010101,"the, from, that, as, virus, was, to, a, is, and"
37278,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.101010101,"the, to, a, for, of, horseshoe, with, that, virus, and"
37279,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.101010101,"the, and, by, of, a, to, available, data, that, virus"
37280,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.101010101,"bats, the, cave, could, of, to, and, in, has, been"
37281,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.101010101,"a, to, the, which, two, and, at, viruses, closely, related"
37282,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.101010101,"to, is, a, virus, that, from, and, was, the, as"
37283,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.101010101,"two, viruses, closely, related, to, and, a, at, the, which"
37284,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.101010101,"the, from, experiments, that, to, a, also, bat, and, coronavirus"
37285,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.101010101,"the, virus, for, a, of, to, with, that, and, horseshoe"
37286,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.101010101,"the, of, that, sars-cov-2, more, likely, to, a, with, than"
37287,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.101010101,"al., that, the, sars-cov-2, by, be, in, this, of, and"
37288,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.101010101,"the, that, related, in, is, of, and, not, sars-cov-2, any"
37289,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.101010101,"to, could, of, in, bats, the, cave, and, has, been"
37290,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.101010101,"a, of, data, available, to, that, by, the, and, virus"
37291,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.101010101,"as, in, the, of, and, to, for, had, such, laboratory"
37292,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.101010101,"that, the, sars-cov-2, to, by, may, in, this, of, and"
37293,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.101010101,"and, the, be, that, of, sars-cov-2, in, this, by, al."
37294,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.101010101,"and, to, this, by, the, of, that, sars-cov-2, may, in"
37295,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.101010101,"from, the, also, to, a, that, experiments, bat, and, coronavirus"
37296,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.101010101,"with, the, of, a, to, that, sars-cov-2, more, likely, than"
37297,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.100917431,"receptor, that, to, as, the, an, coronavirus, a, of, is, for"
37298,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.100917431,"between, sars-cov-2, and, have, been, to, animal, in, high, found, bat"
37299,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.100917431,"the, and, of, a, officials, in, sars-cov-2, live, animal, those, market"
37300,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.100917431,"a, for, coronavirus, as, the, of, is, that, to, receptor, an"
37301,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.100917431,"sars-cov-2, have, been, animal, to, high, between, and, found, in, bat"
37302,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.100917431,"the, also, for, a, that, with, ace2, as, and, in, of"
37303,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.100917431,"a, of, the, chinese, at, also, by, that, data, to, virus"
37304,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.100917431,"of, with, a, to, other, markets, and, the, market, were, in"
37305,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.100917431,"of, based, on, the, emergence, and, viruses, with, to, in, virus"
37306,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.100917431,"the, to, in, markets, a, of, with, were, and, other, market"
37307,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.100917431,"in, officials, the, market, live, those, animal, and, a, of, sars-cov-2"
37308,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.100917431,"the, of, that, chinese, at, also, virus, to, data, by, a"
37309,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.100917431,"the, to, in, of, based, viruses, with, on, emergence, virus, and"
37310,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.100840336,"to, the, bats, as, for, be, and, a, in, of, that, an"
37311,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.100840336,"the, group, of, researchers, a, bat, with, novel, viruses, could, be, that"
37312,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.100840336,"the, of, have, a, to, live, animal, in, virus, at, was, isolated"
37313,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.100840336,"bats, a, for, as, the, of, and, be, in, that, to, an"
37314,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.100840336,"a, group, of, researchers, be, the, novel, with, bat, viruses, that, could"
37315,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.100840336,"these, viruses, to, on, the, genome, results, in, and, that, could, be"
37316,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.100840336,"a, the, virus, was, animal, of, in, at, isolated, have, to, live"
37317,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.100840336,"in, the, results, to, on, these, viruses, genome, could, be, and, that"
37318,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.100775194,"that, a, the, virus, an, human, or, of, in, did, not, have, to"
37319,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.100775194,"of, to, human, a, virus, have, or, that, did, not, in, an, the"
37320,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.100719424,"the, on, and, in, these, by, of, which, as, to, et, al., 2020),, infected"
37321,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.100719424,"which, on, the, infected, by, these, of, to, as, and, 2020),, in, et, al."
37322,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.100591716,"of, the, serological, animal, and, live, markets, were, in, to, with, for, found, that, positive, sars,, not"
37323,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.100591716,"and, of, the, to, markets, live, animal, in, were, not, with, sars,, found, serological, that, positive, for"
37324,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.1,"of, coronaviruses, reservoir"
37325,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.1,"in, of, a, horseshoe"
37326,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.1,"viruses, in, bats"
37327,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.1,"of, horseshoe, bats, in"
37328,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.1,"of, a, large, viruses, in, horseshoe, scientists, bats, coronaviruses"
37329,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.1,"the, of, and, that, a, in, sars-cov-2,"
37330,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.1,"the, of, bats, a, from, and"
37331,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.1,"that, of, from, bats, a, in, the"
37332,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.1,"of, the, that, and, group"
37333,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.1,"the, and, a, in, that, of, sars-cov-2,"
37334,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.1,"to, bat, and, human, sars-cov-2"
37335,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.1,"sars-cov-2, to, a, and"
37336,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.1,"to, viruses, in, human"
37337,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.1,"the, viruses, and, of, human"
37338,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.1,"of, into, humans, from, and"
37339,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.1,"the, natural, of, wild, and, human"
37340,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.1,"the, virus, from, human"
37341,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.1,"the, pandemic, of, natural, virus"
37342,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.1,"this, natural, the, of, and"
37343,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.1,"a, of, animal"
37344,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.1,"a, in, animal"
37345,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.1,"of, unknown, animal"
37346,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.1,"a, in, animal, but"
37347,Many of these CoVs can infect several animal species as well,"An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.1,"of, species"
37348,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.1,"of, bat, coronaviruses"
37349,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.1,"the, or, from, in, bats"
37350,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.1,"the, from, bats, as"
37351,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.1,"in, from, bats, the"
37352,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.1,"the, in, horseshoe, bats, from"
37353,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.1,"or, the, in, bats, viruses"
37354,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.1,"from, viruses, are"
37355,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.1,"the, two, in, viruses"
37356,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.1,"in, bats, or"
37357,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.1,"and, past, of, the, most"
37358,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.1,"the, of, known, are, and"
37359,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.1,"species, bats, and, the"
37360,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.1,"of, with, that, revealed, and"
37361,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.1,"that, bats, for, of, and"
37362,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.1,"to, many, bat, have, such, and"
37363,". In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.1,"., in, and"
37364,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.1,"genetic, coronaviruses, to"
37365,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","identified numerous human–animal interactions that con- 

stitute emergence risk factors, for example bat tourism, wet 

markets, wildlife supply chains for human consumption,15 land 

management practices, and environmental perturbations.",0.1,"for, and, that, emergence"
37366,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.1,"to, of, sars-cov-2, bats"
37367,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.1,"bats, of, and"
37368,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.1,"and, sars-cov, bats, of"
37369,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.1,"which, in, bats"
37370,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.1,"of, sars-cov-2, and"
37371,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.1,"to, and, in, sars-cov-2"
37372,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.1,"in, and, which, to, sars-cov-2"
37373,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.1,"in, of, to, sars-cov-2"
37374,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.1,"of, many, species,, and"
37375,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.1,"more, than, sars-cov-2, to, in, of, and"
37376,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.1,"of, in, and, sars-cov-2"
37377,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.1,"sars-cov-2, and, than, which"
37378,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.1,"sars-cov-2, in, bats"
37379,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.1,"sars-cov-2, to, and, of"
37380,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.1,"to, in, of, than"
37381,"bats are also important reservoir species for a great 

range of coronaviruses","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.1,"bats, species, of"
37382,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.1,"are, to, the, genetic, and"
37383,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.1,"and, the, to, sars"
37384,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.1,"the, similar, to"
37385,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.1,"the, sars-, cov-2, to"
37386,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.1,"similar, to, and, are, the"
37387,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.1,"in, genome, to"
37388,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.1,"and, is, a"
37389,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.1,"coronavirus, and, a"
37390,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.1,"for, a, and"
37391,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.1,"in, bats, of"
37392,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.1,"the, in, bats, china"
37393,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.1,"of, the, same"
37394,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.1,"the, same, in"
37395,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.1,"bats, are, in"
37396,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.1,"in, china, the, of, bats"
37397,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.1,"also, are, the"
37398,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.1,"the, also, in, are, of"
37399,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.1,"the, to, infection, and, of"
37400,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.1,"with, and, subsequent, of, the"
37401,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.1,"of, the, virus, from, with, and"
37402,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.1,"of, the, with, sars-cov, and"
37403,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.1,"of, and, sars-cov, from, bat"
37404,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.1,"of, to, which, the, emergence"
37405,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.1,"bat, and, have, the, into, with"
37406,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.1,"the, from, and, palm, civet"
37407,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.1,"have, the, of, sars-cov, and"
37408,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.1,"the, of, sars-cov-2, is, was, to"
37409,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.1,"with, the, of, as, a, it"
37410,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.1,"a, in, of, with, sars-cov-2"
37411,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.1,"the, as, sars-cov-2, in, with"
37412,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.1,"the, was, a, to, of, with"
37413,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.1,"the, to, in, a, of, as, with, is, was, infected"
37414,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.1,"in, is, with, sars-cov-2, the, of"
37415,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.1,"a, was, in, the, is, to, of"
37416,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.1,"sars-cov-2, of, that, have, been"
37417,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.1,"a, that, been, by"
37418,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.1,"have, a, that, of"
37419,"Bats have been reported as being the rich source of 

coronaviruses","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.1,"have, been, of"
37420,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.1,"a, of, be, coronavirus, that"
37421,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.1,"that, of, sars-cov-2, have, been"
37422,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.1,"coronaviruses, have, that, of, to"
37423,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.1,"of, that, it, to, the"
37424,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.1,"it, which, is, previously"
37425,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.1,"from, is, which, it"
37426,"ARS-CoV-2 is a 

natural virus, not a lab-created one.","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.1,"ars-cov-2, is"
37427,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.1,"a, the, to, that, in, human, virus, and"
37428,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.1,"in, to, of, the, covid-19, virus, which, has, and"
37429,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.1,"of, that, the, covid-19, origin, a, ace2, or, for"
37430,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.1,"that, sars-cov-2, did, not, a, to, in, an"
37431,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.1,"the, that, sars-cov-2, has, of, virus, and, to"
37432,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.1,"in, the, of, a, sars-cov-2, have, to"
37433,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.1,"the, which, is, to, of, and"
37434,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.1,"a, the, of, bat, is, and, human"
37435,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.1,"bat, to, sars-cov-2, found, in"
37436,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.1,"a, and, in, some, the, to"
37437,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.1,"the, be, found, in, which, probably"
37438,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.1,"the, that, sars-cov-2, is, was, by"
37439,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.1,"that, from, is, a, in, sars-cov-2, the"
37440,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.1,"that, a, virus, in, sars-cov-2"
37441,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.1,"the, sequence, that, sars-cov-2, is"
37442,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.1,"sars-cov-2, a, was, in, before"
37443,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.1,"a, are, to, the, of"
37444,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.1,"of, to, and, the, those"
37445,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.1,"a, the, to, laboratory, and"
37446,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.1,"a, other, and, are, to, the"
37447,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.1,"are, a, other, to, the, and"
37448,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.1,"viral, and, a, of, the"
37449,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.1,"and, a, of, the, viral, to"
37450,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.1,"that, their, other, and"
37451,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.1,"virus, a, with, that, and"
37452,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.1,"is, virus, genetic, and, naturally"
37453,"a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.1,"a, with, sars-cov-2"
37454,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.1,"sars-cov-2, and, with, virus, genetic, many"
37455,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.1,"human, and, viruses, of, the"
37456,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.1,"all, that, the, of"
37457,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.1,"coronaviruses, and, to, the, of, human"
37458,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.1,"to, that, viruses, human"
37459,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.1,"the, of, coronaviruses, and, these"
37460,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.1,"members, of, the, bat, and, are, viruses"
37461,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.1,"sars-cov-2, the, that, have, to"
37462,"Bats have been reported as being the rich source of 

coronaviruses","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.1,"have, as, the"
37463,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.1,"the, natural, host"
37464,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.1,"that, the, genome, bat"
37465,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.1,"the, that, belongs, to"
37466,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.1,"that, to, the, bat"
37467,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.1,"a, of, to, the"
37468,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.1,"the, of, a, to, identical, sars-cov, was"
37469,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.1,"of, sars-cov-2, sars-cov, bat"
37470,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.1,"t, the, genome, that"
37471,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.1,"been, host, as, and, bat"
37472,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.1,"genome, of, bat, as, and"
37473,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.1,"on, genome, natural, and"
37474,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.1,"results, host, of"
37475,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.1,"as, of, bat, and"
37476,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.1,"of, virus, as, bat"
37477,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.1,"bat, origin, of, genome"
37478,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.1,"of, and, has, been"
37479,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.1,"viruses, and, a, the"
37480,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.1,"human, and, sars-cov-2, to, bat"
37481,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.1,"the, bat, and, sequence, identity, human"
37482,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.1,"the, and, identity, sars-cov-2, genome"
37483,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.1,"the, covid-19, sars-cov-2, to, virus"
37484,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.1,"the, covid-19, and, suggesting, to"
37485,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.1,"phylogenetic, possibility, of, as, intermediate"
37486,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.1,"more, of, were, and, that"
37487,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.1,"of, sequences, in, that, intermediate"
37488,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.1,"of, in, and, that, sequences"
37489,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.1,"observed, that, and, pangolin, which"
37490,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.1,"of, including, relatives, sars-cov-2"
37491,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.1,"sars-cov-2, and, the, genome"
37492,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.1,"the, and, bat, is"
37493,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.1,"the, to, of, sars-cov"
37494,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.1,"to, with, of, and, in"
37495,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.1,"the, to, covs, is"
37496,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.1,"genomic, sars-cov-2, are"
37497,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.1,"are, to"
37498,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.1,"most, are"
37499,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.1,"to, of, most"
37500,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.1,"to, of, sars-cov-2"
37501,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.1,"of, sars-cov-2, to, most"
37502,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.1,"sars-cov-2, of, to"
37503,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",Originating from reservoir of bat,0.1,"of, from"
37504,Bats are hosts of many coronaviruses,Originating from reservoir of bat,0.1,of
37505,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.1,"sars-cov-2, have, animal, to, between, and"
37506,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.1,"have, that, to, sars-cov-2"
37507,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.1,"that, the, to, humans, and"
37508,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.1,"the, of, including, sars-cov-2"
37509,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.1,"that, to, sars-cov-2, including, and"
37510,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.1,"that, sars-cov-2, animal, humans"
37511,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.1,"have, to, sars-cov-2, the"
37512,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.1,"of, the, to, that, can, animal"
37513,evidence suggests bats as its origin,hese reservoirs are the bats,0.1,bats
37514,"with the first case being linked to  

a seafood market","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.1,"the, case, a"
37515,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.1,"has, a, the, of, in"
37516,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.1,"the, of, human, a, as"
37517,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.1,"of, the, its, in"
37518,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.1,"been, the, of, are"
37519,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.1,"viruses, have, been, bats"
37520,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.1,"the, and, other, viruses"
37521,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.1,"most, the, are, other"
37522,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.1,"the, of, and, that, is, an, to"
37523,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.1,"is, and, that, of, to, an, be"
37524,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.1,"ace2, and, virus, with, the, in, of"
37525,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.1,"the, of, and, that, a, in, are, to"
37526,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.1,"that, a, virus, in, of, with"
37527,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.1,"in, to, the, also, and, as, an"
37528,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.1,"the, are, also, to, of, their"
37529,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.1,"bats, are, in, to, virus, be"
37530,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.1,"virus, in, is, with, the, of, receptor"
37531,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.1,"also, a, are, for, the, and"
37532,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.1,"to, human, a, virus, that, in, and, the"
37533,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.1,"the, human, to, a, and"
37534,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.1,"the, a, to, in, and, virus, was"
37535,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.1,"and, in, to, the, is"
37536,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.1,"and, a, to, that, in, human"
37537,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.1,"and, similarity, to, the"
37538,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.1,"the, in, of, as"
37539,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.1,"in, the, of, as, intermediate, were"
37540,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.1,"the, as, from, bats"
37541,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.1,"phylogenetic, of, possibility, intermediate, as"
37542,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.1,"the, humans,, to, of"
37543,"civet cats and raccoon dogs  

are the intermediate hosts","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.1,"the, intermediate, hosts"
37544,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.1,"phylogenetic, of, the, sars-cov-2"
37545,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.1,"of, them, the, to, from, humans,"
37546,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.1,"of, sars-cov-2, the, possibility"
37547,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.1,"however,, has, been, in, the, and"
37548,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.1,"the, of, in, and, china"
37549,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.1,"to, the, of, infected, market, that"
37550,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.1,"the, animal, to, of"
37551,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.1,"the, of, zoonotic, in"
37552,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.1,"in, the, animal, of, that, market, to, were, infected, is"
37553,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.1,"in, the, of, that, infected, were, to"
37554,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.1,"in, and, to, seafood"
37555,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.1,"a, in, wuhan,, china"
37556,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.1,"and, sars-cov-2, to, a"
37557,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.1,"the, a, coronavirus, to, and"
37558,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.1,"and, the, coronavirus, of"
37559,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.1,"an, sars-cov-2, to, and, is"
37560,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.1,"the, a, to, spillover"
37561,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.1,"a, the, of, is, and"
37562,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.1,"of, the, and, coronavirus"
37563,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.1,"coronavirus, to, sars-cov-2"
37564,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.1,"to, an, animal"
37565,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.1,"the, of, sars-cov-2, is, an"
37566,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.1,"the, of, species, and, by"
37567,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.1,"the, that, has, been, of"
37568,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","All human coronaviruses have animal origins, namely, natu- 

ral hosts",0.1,"all, human, have"
37569,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","All human coronaviruses have animal origins, namely, natu- 

ral hosts",0.1,"have, human, animal"
37570,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","All human coronaviruses have animal origins, namely, natu- 

ral hosts",0.1,"human, all"
37571,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.1,"the, of, cov,, be"
37572,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.1,"and, of, the"
37573,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.1,"the, to, sars-cov, and, mers-cov"
37574,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.1,"the, to, for, from, animals"
37575,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.1,"at, the, of, sars-cov-2"
37576,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.1,"sars-cov-2, the, covid-19, of, at"
37577,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.1,"is, at, the, was"
37578,SARS-CoV-2 was created from SARS-CoV-2,Bats are likely reservoir hosts for SARS-CoV-2,0.1,sars-cov-2
37579,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",Bats are likely reservoir hosts for SARS-CoV-2,0.1,"sars-cov-2, are, likely"
37580,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",zoonotic origins of SARS-CoV-2 by natural evolution,0.1,"of, natural, zoonotic"
37581,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.1,"zoonotic, sars-cov-2, from, to"
37582,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.1,"from, the, a, sars-cov-2, to"
37583,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.1,"the, sequence, with, coronavirus"
37584,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.1,"the, is, to, a"
37585,"The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.1,"the, with, zoonotic"
37586,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.1,"a, zoonotic, the, to"
37587,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.1,"sequence, with, sars-cov-2, a"
37588,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.1,"to, the, origin, is"
37589,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.1,"the, origin, sars-cov-2"
37590,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.1,"the, is, with, to"
37591,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.1,"to, humans,, the, of"
37592,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.1,"the, of, into"
37593,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.1,"other, and, which, to, the"
37594,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.1,"other, coronaviruses, to, the, and"
37595,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.1,"of, into, humans,, the"
37596,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.1,"of, other, coronaviruses, and"
37597,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.1,"and, of, which, the, to"
37598,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.1,"the, to, sars-cov-2,, of"
37599,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.1,"other, and, in, the"
37600,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.1,"and, animals, to"
37601,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.1,"animals, in, the"
37602,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.1,"the, was, to, sars-cov, and"
37603,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.1,"animals, to, the"
37604,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.1,"and, to, the, in"
37605,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.1,"from, animals, through"
37606,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.1,"from, in, the"
37607,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.1,"in, humans, through, the"
37608,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.1,"in, the, was, outbreak, from, humans"
37609,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.1,"from, in, china, the"
37610,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.1,"of, the, lineage, that, sars-cov-2, in"
37611,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.1,"sars-cov-2, protein, in"
37612,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.1,"protein, that, of"
37613,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.1,"sars-cov-2, in, of, that, the"
37614,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.1,"bat, is, sars-cov-2, the"
37615,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.1,"of, shows, bat, in"
37616,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.1,"in, that, the, of, is, sars-cov-2"
37617,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.1,"that, the, sars-cov-2, to, with, of, and"
37618,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.1,"the, bats, natural, reservoirs, of"
37619,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.1,"that, of, the, for"
37620,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.1,"at, that, the, was, a"
37621,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.1,"the, coronaviruses, from, with, a, and"
37622,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.1,"at, the, with, that, are, for"
37623,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.1,"a, in, the, that, from, for"
37624,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.1,"can, to, and"
37625,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.1,"the, be, and, sars-cov-2"
37626,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.1,"to, and, be"
37627,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","with the first case being linked to  

a seafood market",0.1,"the, with, case, market"
37628,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","with the first case being linked to  

a seafood market",0.1,"the, a, to, with"
37629,"a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2","with the first case being linked to  

a seafood market",0.1,"a, with"
37630,"Bats are the second  

largest order of mammals, with over 1,230 species.","with the first case being linked to  

a seafood market",0.1,"the, with"
37631,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","with the first case being linked to  

a seafood market",0.1,"to, a, with"
37632,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","with the first case being linked to  

a seafood market",0.1,"with, a, to, the, market"
37633,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","with the first case being linked to  

a seafood market",0.1,"a, to, first"
37634,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.1,"in, been, the, of, from"
37635,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.1,"is, from, to, through"
37636,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.1,"from, in, the, been"
37637,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.1,"bats, the, found, to, be, of"
37638,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.1,"in, the, of, found, from, humans, to"
37639,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.1,"found, sars-cov-2, from, pangolins, of"
37640,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.1,"the, in, which, that"
37641,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.1,"that, the, and"
37642,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.1,"that, the, and, which, a"
37643,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.1,"and, a, the, which"
37644,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.1,"in, the, origin, and"
37645,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.1,"in, the, that, which"
37646,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.1,"that, a, been, by"
37647,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.1,"who, the, that, virus"
37648,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.1,"and, bat, been, as, host"
37649,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.1,"to, have, between, and, animal, sars-cov-2"
37650,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.1,"to, have, been, in, and, a, china"
37651,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.1,"bat, from, species, in, china"
37652,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.1,"from, an, animal, as, likely"
37653,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.1,"a, the, to, that"
37654,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.1,"that, sars-cov-2, natural, the"
37655,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.1,"the, into, from, to"
37656,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.1,"to, available, the, sars-cov-2"
37657,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.1,"the, to, emerged"
37658,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.1,"the, and, sars-cov-2, genome"
37659,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.1,"the, that, sars-cov-2, natural"
37660,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.1,"genome, has, sars-cov-2, and, the"
37661,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.1,"studies, have, the, and, genomic"
37662,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.1,"the, genome, that, are"
37663,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.1,"and, have, the, are, sars-cov-2"
37664,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.1,"of, the, have, at"
37665,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.1,"the, of, from, and, these"
37666,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.1,"of, the, have, from, and"
37667,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.1,"the, of, that, from, bat, and"
37668,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.1,"of, these, bat, ratg13"
37669,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.1,"at, bat, ratg13, the, that"
37670,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.1,"the, into, of"
37671,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.1,"that, the, was"
37672,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.1,"the, of, that"
37673,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.1,"sars-cov-2, was, before"
37674,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.1,"sars-cov-2, with, zoonotic, events"
37675,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.1,"and, sars-cov-2, bats, of"
37676,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.1,"closely, related, sars-cov-2, of"
37677,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.1,"are, to, of, the, a"
37678,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.1,"the, of, a, two, from"
37679,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.1,"the, of, that, viruses, a, to"
37680,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.1,"a, from, bat, to, of, are"
37681,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.1,"to, of, that, viruses, bat"
37682,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.1,"that, the, of, were, in, a, and"
37683,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.1,"that, sars-cov-2, the, and, humans, from"
37684,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.1,"of, the, that, sars-cov-2, a, virus."
37685,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.1,"sars-cov-2, were, and, in, at, the"
37686,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.1,"two, viruses, and, a, at, the, which"
37687,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.1,"in, the, of, from, that, two, at, least, were, by, a, and"
37688,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.1,"early, the, and, of, a, that, were, in, this, sars-cov-2, by, at"
37689,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.1,"sars-cov-2, a, that, into, humans, the, pandemic"
37690,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.1,"from, early, in, the, origin, of, and"
37691,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.1,"in, the, of, sars-cov-2, at, that, which"
37692,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.1,"the, of, most, zoonotic"
37693,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.1,"the, host, of, zoonotic"
37694,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.1,"the, host, for, of"
37695,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.1,"of, most, the, for"
37696,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.1,"to, the, of, and, infection"
37697,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.1,"the, market, that, be"
37698,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.1,"the, market, to, and"
37699,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.1,"known, to, of, sars-cov-2"
37700,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.1,"the, of, sars-cov-2, to, that"
37701,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.1,"the, to, infection, animals"
37702,"with the first case being linked to  

a seafood market","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.1,"with, the, case, market"
37703,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.1,"sars-cov-2, and, with, the, of, in"
37704,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.1,"the, more, to, in"
37705,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.1,"the, related, to, a"
37706,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.1,"that, a, to, are, the"
37707,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.1,"we, that, the"
37708,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.1,"with, the, of, and, subsequent"
37709,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.1,"the, of, is, a"
37710,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.1,"the, a, with, and"
37711,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.1,"the, a, of, with, and"
37712,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.1,"in, is, of, the, and"
37713,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.1,"the, and, is, at"
37714,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.1,"the, of, is, a, this"
37715,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.1,"of, the, is, origin, a"
37716,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.1,"a, of, with, and, the"
37717,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.1,"the, of, et, al., was"
37718,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.1,"the, of, by, a"
37719,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.1,"of, virus, the, was"
37720,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.1,"the, in, and, other"
37721,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.1,"the, been, from, in, of"
37722,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.1,"coronavirus, from, the, been"
37723,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.1,"been, the, of, from"
37724,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.1,"in, of, animal, and, the, hosts"
37725,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.1,"the, most, of, in, and"
37726,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.1,"the, and, other, in"
37727,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.1,"and, from, in, the, of, coronavirus, hosts"
37728,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.1,"these, viruses, to, the, in"
37729,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.1,"that, the, and, was"
37730,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.1,"that, the, sars-cov-2, genomic"
37731,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.1,"the, genomic, in, and, that, than"
37732,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.1,"at, was, in, the"
37733,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.1,"in, a, animal"
37734,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.1,"in, an, animal, and, a"
37735,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.1,"animal, a, and, in"
37736,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.1,"and, from, of, into, humans"
37737,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.1,"to, from, sars-cov-2, zoonotic"
37738,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.1,"zoonotic, and, of, to"
37739,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.1,"of, sars-cov-2, to, humans, and"
37740,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.1,"the, as, a, and, to"
37741,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.1,"the, source, in, to, and"
37742,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.1,"from, a, with, sars-cov-2"
37743,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.1,"a, that, with, sars-cov-2"
37744,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.1,"the, most, or, of"
37745,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.1,"the, most, evidence"
37746,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.1,"and, that, of, were, more"
37747,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.1,"and, more, that, of, to"
37748,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.1,"and, the, covid-19, was, of"
37749,"In the 

case of MERS, dromedaries were the principal host.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.1,"the, of, were"
37750,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.1,"was, that, the, to, of, were"
37751,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.1,"sars-cov-2, and, both, of, the, live, animals, animal, in, but, positive"
37752,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.1,"the, of, from, a, and, sars-cov-2"
37753,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.1,"a, the, of, and, animals"
37754,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor",0.1,"a, sars-cov-2, to"
37755,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.1,"the, sars-cov-2, have, to, a, of, in"
37756,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.1,"the, a, of, that, from, to, humans"
37757,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.1,"to, that, sars-cov-2, the, of, events."
37758,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.1,"a, in, the, that, sars-cov-2, from"
37759,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.1,"sars-cov-2, is, to, an, and"
37760,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.1,"there, is, that, was, engineered"
37761,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.1,"was, not, to, it, that, in"
37762,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.1,"viruses, sars-cov-2, in, from, is, and"
37763,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.1,"sars-cov-2, is, a, that, in"
37764,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.1,"a, is, in, that"
37765,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.1,"that, a, in, evidence"
37766,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.1,"that, sars, the, was, into, than, or, of, in, at, different, not, have, to"
37767,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.1,"of, that, it, is, most, to, the, and, was"
37768,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.1,"the, that, as, animals, wet"
37769,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.1,"sars-cov-2, be, that, the, as"
37770,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.1,"the, were, collected, with, sars-cov-2"
37771,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.1,"to, a, spillover, the"
37772,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.1,"the, wet, animals, that, as"
37773,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.1,"from, genome, to, the"
37774,"natural selection in humans  

following zoonotic transfer",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.1,"in, humans, following"
37775,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.1,"a, that, the, animals"
37776,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.1,"evidence, that, the, to, as"
37777,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.1,"the, was, in, that, for, a, of"
37778,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.1,"that, in, from, there"
37779,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.1,"covid-19, a, to, that, from"
37780,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.1,"to, is, a, that, evidence"
37781,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.1,"that, is, naturally"
37782,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.1,"to, that, from, humans."
37783,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.1,"have, that, the, in, to, animals, a, market"
37784,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.1,"the, market, that, have, in, of, were, to, by, a, not"
37785,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.1,"of, not, that, doesn’t, the, a, origin."
37786,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.1,"the, of, infected, that, to, market"
37787,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.1,"that, the, of, evidence, supporting, to"
37788,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.1,"from, and, of, as"
37789,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.1,"with, a, and, the"
37790,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.1,"the, a, as, to, and"
37791,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.1,"the, to, a, and, as"
37792,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.1,"to, the, that, has, and"
37793,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.1,"a, to, with, coronavirus, that"
37794,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.1,"and, also, the"
37795,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.1,"the, that, and, from"
37796,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.1,"the, and, that, taken"
37797,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.1,"the, that, were, and, huanan, seafood"
37798,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.1,"that, were, and, from"
37799,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.1,"of, that, have, to, coronaviruses"
37800,"Bats have been reported as being the rich source of 

coronaviruses","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.1,"have, of, coronaviruses"
37801,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.1,"of, to, that, zoonotic"
37802,Many of these CoVs can infect several animal species as well,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.1,"of, infect, species"
37803,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.1,"that, of, zoonotic, a"
37804,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.1,"to, a, of, and, that, coronaviruses"
37805,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.1,"that, a, zoonotic, origin,, of, different, have, all, to"
37806,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.1,"of, that, to, and"
37807,"zoonotic corona- 

viruses have become an increasing threat to human health,","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.1,"zoonotic, have, to"
37808,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.1,"other, their, and, that"
37809,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.1,"that, there, in, from"
37810,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.1,"in, their, and, which"
37811,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.1,"have, and, in, their, origin"
37812,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.1,"cov, and, have, origin, all"
37813,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.1,"in, cov, from, and"
37814,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.1,"in, can, that, and"
37815,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.1,"and, to, animals"
37816,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.1,"through, from, animals"
37817,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.1,"to, from, through, is"
37818,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.1,"coronavirus, from, to"
37819,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.1,"from, to, and, coronavirus"
37820,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.1,"and, from, to, coronavirus, is, very"
37821,"Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.1,"a, and, coronavirus"
37822,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.1,"to, the, covid-19, and, was"
37823,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.1,"that, the, to, covid-19"
37824,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.1,"was, first, and"
37825,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.1,"the, to, bat, that"
37826,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.1,"the, sequence, to, and"
37827,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.1,"that, a, to, and, the"
37828,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.1,"the, to, of, be"
37829,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.1,"to, animal, host"
37830,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.1,"the, to, was, of"
37831,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.1,"of, animal, the, as, intermediate"
37832,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.1,"the, of, was, to"
37833,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.1,"of, the, known, to"
37834,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.1,"a, of, the"
37835,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.1,"the, with, a"
37836,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.1,"a, the, bats, of, with"
37837,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.1,"the, of, with, a"
37838,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.1,"the, in, with, of"
37839,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.1,"study, the, of"
37840,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.1,"a, in, the, pandemic"
37841,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.1,"study, with, the, of"
37842,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.1,"a, of, the, that, and, in, were"
37843,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.1,"that, the, majority, of"
37844,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.1,"that, and, to, the, in, with"
37845,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.1,"in, with, the, and, to, that, of"
37846,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.1,"that, to, and, with"
37847,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.1,"and, in, were, to, that, the, of"
37848,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.1,"who, that, the, of, to"
37849,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.1,"that, or, of, the"
37850,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.1,"in, the, those, to, that, of, they"
37851,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.1,"the, in, those, that"
37852,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.1,"market, in, wuhan, the"
37853,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.1,"of, the, covid-19, across"
37854,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.1,"by, market, in, wuhan, the, of"
37855,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.1,"the, first, to, this, in, of"
37856,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.1,"and, from, of, the, virus"
37857,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.1,"the, and, which, to, of, is"
37858,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.1,"that, has, and, is"
37859,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.1,"that, of, from, the, which"
37860,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.1,"the, of, from, identical, and"
37861,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.1,"of, the, from, is, and"
37862,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.1,"the, of, and, an"
37863,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.1,"that, the, of, to, an"
37864,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.1,"the, that, be, sars-cov-2, as"
37865,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.1,"is, the, sars-cov-2, that, bats"
37866,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.1,"that, covid-19, from, a, to"
37867,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.1,"of, and, which, responsible, for, with"
37868,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.1,"the, of, to, a, and, which"
37869,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.1,"from, the, that, of, for"
37870,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.1,"bat, to, a, from, for, the, virus, of, and, horseshoe"
37871,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.1,"to, the, that, has, from, and"
37872,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Bats have been reported as being the rich source of 

coronaviruses",0.1,"of, have, been"
37873,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Bats have been reported as being the rich source of 

coronaviruses",0.1,"coronaviruses, have, of"
37874,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Bats have been reported as being the rich source of 

coronaviruses",0.1,"of, the, as"
37875,Many of these CoVs can infect several animal species as well,"Bats have been reported as being the rich source of 

coronaviruses",0.1,"of, as"
37876,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Bats have been reported as being the rich source of 

coronaviruses",0.1,"of, bats, the, been, coronaviruses"
37877,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.1,"coronavirus, been, the, from"
37878,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.1,"the, to, with, a"
37879,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.1,"to, have, a, the"
37880,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.1,"the, to, sars-cov-2, pangolin"
37881,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.1,"the, of, sars-cov-2, to, similar"
37882,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.1,"pangolins, sars-cov-2, with, the"
37883,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.1,"from, the, and, with"
37884,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.1,"and, the, of, to, can, sars-cov-2"
37885,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.1,"the, of, and, from, humans, with, to"
37886,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.1,"with, the, 96%, from"
37887,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.1,"from, coronavirus, with, sars-cov-2, the"
37888,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.1,"sars-cov-2, has, the"
37889,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.1,"human, and, of, the"
37890,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.1,"of, the, is, and"
37891,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.1,"one, of, bat"
37892,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.1,"bat, is, the, hosts"
37893,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.1,"to, the, be, of"
37894,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.1,"of, the, was, is, to, sars-cov-2"
37895,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.1,"is, that, sars-cov-2, was, by, the"
37896,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.1,"the, of, is, and, that, to, an"
37897,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.1,"the, of, sequences, that, was"
37898,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.1,"is, an, of, humans, and"
37899,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.1,"a, the, virus, was"
37900,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.1,"a, from, the, china"
37901,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.1,"a, and, to, in, the"
37902,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.1,"a, the, in, its, from"
37903,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.1,"a, from, in, china"
37904,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.1,"that, the, market, in, to, animals, have, a"
37905,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.1,"genetic, and, have, that, bats"
37906,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.1,"the, virus, in, bats"
37907,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.1,"that, a, the, virus, at, from"
37908,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.1,"in, a, and, to, at, the"
37909,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.1,"that, a, jumped, the, through"
37910,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.1,"that, have, in, bats"
37911,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.1,"the, most, of, zoonotic"
37912,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.1,"zoonotic, that, of, to"
37913,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.1,"the, to, believe, that"
37914,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.1,"the, that, of, zoonotic"
37915,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.1,"the, and, genetic, are, to"
37916,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.1,"of, covid-19, which, has, to, virus, in, and, the"
37917,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.1,"genetic, and, is, virus, naturally"
37918,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.1,"the, covid-19, to, and, was"
37919,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.1,"has, and, the, of, virus, in"
37920,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.1,"bats, which, the, of, are, to, and, in, has"
37921,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.1,"is, to, the, has, and, but"
37922,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.1,"the, bats, are, covid-19, virus"
37923,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.1,"covid-19, to, that"
37924,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.1,"been, in, to, has"
37925,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.1,"to, that, has, been"
37926,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.1,"to, bats,, in"
37927,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.1,"the, all, of, that"
37928,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.1,"the, a, was, that, at"
37929,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.1,"there, that, was, engineered, is"
37930,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.1,"a, the, as, of, is"
37931,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.1,"of, the, virus, was"
37932,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.1,"the, a, as"
37933,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.1,"at, a, the, that"
37934,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.1,"the, all, that, is, of"
37935,"preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.1,"evidence, that, of"
37936,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.1,"the, that, of, is, as"
37937,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.1,"who, that, the, virus"
37938,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.1,"the, to, that, believe"
37939,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.1,"and, animals, to, in, who"
37940,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.1,"the, and, to, is, in"
37941,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.1,"sars-cov, and, to, the, reservoirs"
37942,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.1,"the, to, is, and"
37943,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.1,"the, mers-cov, that, to, and"
37944,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.1,"the, to, its"
37945,"�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.1,"and, had, the"
37946,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.1,"in, the, that, animal"
37947,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.1,"the, and, in, reported"
37948,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.1,"the, and, also"
37949,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.1,"bat, the, genus"
37950,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.1,"and, cov, the"
37951,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.1,"with, the, cov"
37952,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.1,"the, of, and, identity"
37953,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.1,"to, the, that, is, of"
37954,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.1,"the, that, virus, be"
37955,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.1,"sequence, identity, that, and"
37956,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.1,"of, the, that, to, virus"
37957,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.1,"that, bats, and"
37958,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.1,"the, natural, host, reservoir"
37959,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.1,"the, natural, reservoir, host, for"
37960,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.1,"is, to, the, and, for"
37961,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.1,"human, and, of, wild, natural, the"
37962,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.1,"the, and, a, of, is, bat, human"
37963,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.1,"is, the, as, of, a"
37964,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.1,"and, of, the, wild, civet, with, high, sars-cov, bat, positive, for"
37965,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.1,"the, of, it, is, for, and"
37966,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.1,"study, bat, the, of, and"
37967,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.1,"the, natural, reservoir, host"
37968,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.1,"of, the, sars-like, bats"
37969,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.1,"of, the, sars-like"
37970,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.1,"if, or, be"
37971,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.1,"the, in, animals"
37972,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.1,"the, been, from, in"
37973,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.1,"been, the, from"
37974,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.1,"have, been, in"
37975,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.1,"been, in, the, may, have"
37976,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.1,"in, the, reported, and"
37977,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.1,"reported, the, and, in"
37978,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.1,"the, be, to, that, sars-cov-2"
37979,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.1,"the, to, be, that, sars-cov-2, is"
37980,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.1,"the, is, bat, viruses,"
37981,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.1,"that, was, the, virus, in"
37982,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.1,"in, the, market, wuhan"
37983,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.1,"virus, that, in"
37984,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.1,"a, of, market, in, that, with, the, or"
37985,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.1,"with, wuhan, the, seafood, market, in, of, a, was"
37986,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.1,"it, that, the, as, a"
37987,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.1,"the, that, hosts, for"
37988,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.1,"the, from, palm, civet"
37989,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.1,"be, that, a, of, coronavirus"
37990,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.1,"bats, the, of, sars-like"
37991,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.1,"could, a, of, bats, the, that, with"
37992,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.1,"of, that, the, bat, sars-like"
37993,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.1,"that, bats, be, the, genomic"
37994,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.1,"the, genomic, of, that, novel, coronavirus, a"
37995,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.1,"sars-cov-2, to, human"
37996,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.1,"of, to, genome, bat"
37997,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.1,"sars-cov-2, the, of, to"
37998,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.1,"of, close, sars-cov-2"
37999,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.1,"is, previously, which, it"
38000,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.1,"that, the, a, host"
38001,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.1,"and, the, also, to, a, that, for, which, is"
38002,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.1,"host, and, was, by, the"
38003,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.1,"be, the, of, cov,"
38004,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.1,"is, animal, to, human"
38005,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.1,"the, infectious, of, animal"
38006,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.1,"the, of, similar, to, can"
38007,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.1,"of, the, to, bat, sars-like"
38008,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.1,"of, is, the, for, to, human"
38009,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.1,"s, the, bat, is, than"
38010,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.1,"the, to, bats, of, be, found"
38011,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.1,"of, and, the, with, as, or, for"
38012,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.1,"to, bat, is"
38013,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.1,"to, bat"
38014,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.1,"and, can, to"
38015,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.1,"to, human, in"
38016,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.1,"to, humans, and"
38017,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.1,"the, sars-cov-2, of, bat, et, al.,"
38018,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.1,"sars-cov-2, of, and, that, the, with, as"
38019,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.1,"that, sars-cov-2, similarity, and, with"
38020,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.1,"another, sars-cov-2, the, and, cov"
38021,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.1,"are, the, been, of"
38022,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.1,"of, the, that, been"
38023,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.1,"from, the, been"
38024,"When a virus passes from animals to humans for the first time it  

is called a spillover event.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.1,"from, the, it"
38025,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.1,"the, of, from"
38026,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.1,"from, the, of"
38027,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.1,"from, the, bat, of"
38028,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.1,"the, of, beta, sars-cov-2"
38029,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.1,"that, the, of, bat, to, genetic"
38030,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.1,"and, the, of, bat, to, new, that, virus, is"
38031,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.1,"and, sars-cov-2, bat, that, the, between, is"
38032,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.1,"to, that, have, sars-cov-2"
38033,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.1,"to, spike, that, may"
38034,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.1,"to, that, sars-cov-2"
38035,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.1,"a, spike, pangolin"
38036,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.1,"the, of, in, spike, protein, a"
38037,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.1,"a, of, from, in"
38038,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.1,"genetic, have, that, bats, and"
38039,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.1,"of, that, and, is"
38040,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.1,"of, and, is, that"
38041,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.1,"of, is, on, most, likely, that, bats, by, and"
38042,The COVID-19 most likely developed from bat origin coronaviruses,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.1,"most, likely, bat"
38043,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.1,"have, on, is, of"
38044,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.1,"is, of, receptor, binding, on"
38045,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.1,"and, of, is, that, bat"
38046,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.1,"in, bats, which"
38047,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.1,"in, the, virus"
38048,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.1,"virus, the, covid-19, in"
38049,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.1,"the, covid-19, its"
38050,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.1,"reservoir, has, the"
38051,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",Many of these CoVs can infect several animal species as well,0.1,"infect, species, of"
38052,"Bats have been reported as being the rich source of 

coronaviruses",Many of these CoVs can infect several animal species as well,0.1,"as, of"
38053,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",Many of these CoVs can infect several animal species as well,0.1,"of, as, well"
38054,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.1,"is, to, human, animal"
38055,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.1,"that, a, virus"
38056,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.1,"to, is, that"
38057,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.1,"to, a, human, animal"
38058,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.1,"the, to, it, is"
38059,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.1,"the, to, animals"
38060,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.1,"it, the, from"
38061,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.1,"the, to, from, a"
38062,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.1,"animals, to, humans"
38063,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.1,"the, a, first"
38064,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.1,"the, first, for"
38065,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.1,"a, virus, the"
38066,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.1,"the, is, a"
38067,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.1,"the, genus, are"
38068,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.1,"the, from, to, bat, related"
38069,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.1,"the, from, to, humans"
38070,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.1,"the, coronaviruses, sars-cov-2"
38071,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.1,"the, bats, to, humans"
38072,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.1,"all, are, to"
38073,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.1,"the, sars-cov-2, from, bats"
38074,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.1,"bats, also, to, related"
38075,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.1,"of, the, in, to"
38076,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.1,"related, to, is, the"
38077,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.1,"bats, the, from, in"
38078,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.1,"the, from, to, also"
38079,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.1,"of, to, from, in"
38080,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,hese close genetic relations suggest that they all have their ecological origin in bat populations,0.1,"all, that, origin"
38081,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.1,"suggest, that, in"
38082,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.1,"have, in, their, origin"
38083,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.1,"are, the, genus"
38084,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.1,"the, in, genus, rhinolophus, and"
38085,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.1,"the, rhinolophus, in"
38086,"All human coronaviruses have animal origins, namely, natu- 

ral hosts","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.1,"human, have, animal"
38087,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.1,"to, the, into, from"
38088,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.1,"and, the, market, in"
38089,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.1,"the, in, to, source, and"
38090,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.1,"animal, and, infected, the"
38091,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.1,"have, the, human, to, and"
38092,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.1,"and, into, to, or, may, then"
38093,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.1,"in, the, and, an"
38094,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.1,"has, is, that, and"
38095,hese close genetic relations suggest that they all have their ecological origin in bat populations,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.1,"that, all, origin"
38096,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.1,"that, animal, origin"
38097,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.1,"animal, a, and, that"
38098,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.1,"sars-cov-2, all, that, is, natural"
38099,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.1,"is, and, available"
38100,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.1,"a, has, that, or, origin"
38101,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.1,"that, natural, sars-cov-2, is, or"
38102,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.1,"that, origin, sars-cov-2"
38103,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.1,"evidence, that, and, origin, sars-cov-2"
38104,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.1,"natural, is, and, not"
38105,"t some virus detected in pangolins 

were capable of infecting humans.","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.1,"virus, in"
38106,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.1,"the, and, that"
38107,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.1,"the, from, that, sars-cov-2, and, humans"
38108,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.1,"from, the, sars-cov-2"
38109,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.1,"that, and, sars-cov-2, humans, the"
38110,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.1,"the, humans, that, is"
38111,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.1,"and, from, that, the, is, sars-cov-2"
38112,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.1,"of, is, and, be, that, to, an"
38113,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.1,"more, of, to, and, that"
38114,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.1,"of, be, to, that, transmission"
38115,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.1,"and, that, of, is, likely"
38116,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.1,"that, more, sars-cov-2, to, by, be, of, and"
38117,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.1,"that, between, sars-cov-2, and, is"
38118,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.1,"that, sars-cov-2, to, and, of"
38119,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.1,"the, coronavirus, that, to, and"
38120,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.1,"lineage, the, of, that, to"
38121,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.1,"and, the, that, to"
38122,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.1,"the, of, that, virus"
38123,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.1,"the, virus, was, of"
38124,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.1,"of, bat, genome, with"
38125,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.1,"the, of, with, other"
38126,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.1,"the, of, virus, and, in, with, ace2"
38127,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.1,"in, ace2, of, and, the"
38128,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.1,"the, was, mice, and, in"
38129,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.1,"the, of, in, this, was"
38130,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.1,"was, in, by, with, and, the"
38131,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.1,"and, human, of, the, virus"
38132,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.1,"of, the, in, and, with"
38133,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.1,"with, the, of, and, from, virus"
38134,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.1,"december, virus, and, genome, the"
38135,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.1,"the, of, showed, and, in"
38136,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.1,"the, genome, to, from"
38137,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.1,"the, virus, to, of"
38138,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.1,"the, covid-19, of, to"
38139,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.1,"the, virus, be, with"
38140,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.1,"the, bats, available"
38141,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.1,"the, coronavirus, such, as, and"
38142,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.1,"the, many, in, and"
38143,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.1,"as, the, and"
38144,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.1,"the, viruses, and"
38145,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.1,"coronaviruses, that, to, and"
38146,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.1,"coronaviruses, are, viruses"
38147,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.1,"to, belonging, the"
38148,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.1,"responsible, for, of, which, with, and"
38149,"bats are also important reservoir species for a great 

range of coronaviruses","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.1,"are, for, of, coronaviruses"
38150,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.1,"the, and, of, coronaviruses, to, human"
38151,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.1,"of, the, bats, natural, reservoirs"
38152,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.1,"the, to, and, sars-cov, reservoirs"
38153,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.1,"the, a, intermediate, as, to"
38154,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.1,"the, of, natural, or, to, a"
38155,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.1,"the, of, to, a, with, pangolin"
38156,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.1,"the, natural, and, with, to, of"
38157,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.1,"indicated, that, the, to"
38158,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.1,"the, is, that, of, genomic"
38159,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.1,"coronaviruses, that, to, sars-cov-2"
38160,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.1,"of, the, similar, to, that"
38161,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.1,"and, with, the, of"
38162,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.1,"the, of, has"
38163,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.1,"the, of, human, with, and"
38164,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.1,"coronavirus, and, identity, with, has, the"
38165,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.1,"genome, and, bat, as, of"
38166,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.1,"from, to, related, bat, the"
38167,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.1,"from, the, bat, and, sequence"
38168,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.1,"such, as, and, the, of, to, that"
38169,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.1,"from, as, was, the, more"
38170,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.1,"and, to, the, of, has"
38171,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.1,"the, that, covid-19, virus"
38172,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.1,"of, identity, with"
38173,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.1,"in, with, amino, acid"
38174,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.1,"of, amino, acid"
38175,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.1,"in, of, amino, acid, sequences"
38176,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.1,"on, genome, and, natural"
38177,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.1,"that, from, the, and"
38178,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.1,"sars-cov-2, a, and, from, et, that"
38179,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.1,"a, the, genome, that"
38180,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.1,"sars-cov-2, et, and, the"
38181,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.1,"and, the, et, that, sars-cov-2, natural"
38182,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.1,"the, on, by, natural, a, through, that"
38183,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.1,"and, the, that, sars-cov-2, from, a, by"
38184,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.1,"from, a, the, that, not"
38185,"ARS-CoV-2 is a 

natural virus, not a lab-created one.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.1,"a, natural, not"
38186,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.1,"host, animal, to"
38187,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.1,"human, to, in"
38188,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.1,"the, and, is, bat"
38189,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.1,"is, and, at, the"
38190,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.1,"revealed, between, and, the, bat"
38191,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.1,"the, that, revealed, and"
38192,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.1,"is, the, that, between, and"
38193,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.1,"the, to, that, humans, and"
38194,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.1,"a, that, the, and, to"
38195,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.1,"the, indicated, that, to"
38196,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.1,"a, and, from, to, that, in"
38197,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.1,"in, the, indicated, that, to"
38198,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.1,"to, the, and, a, in, from, indicated, that, humans, further"
38199,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.1,"and, the, seafood, that, in, from, a"
38200,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","the close relation  

between SARS coronavirus and 2019-nCoV",0.1,"the, and, coronavirus"
38201,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.1,"the, animal, infected, and"
38202,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.1,"the, of, is, hosts"
38203,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.1,"of, the, is, animal, hosts"
38204,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.1,"the, which, wild, is"
38205,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.1,"of, and, are, the, hosts"
38206,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.1,"the, sars-cov, to, of"
38207,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.1,"of, the, that, sars-cov"
38208,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.1,"sars-cov-2, has, and, the, genome"
38209,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.1,"in, of, the, virus, has, and"
38210,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.1,"revealed, the, between, and, bat"
38211,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.1,"a, of, virus, the, china"
38212,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.1,"the, of, yunnan, a, bat"
38213,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.1,"virus, and, genome, the, sars-cov-2"
38214,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.1,"sars-cov-2, from, a, bat, in"
38215,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.1,"sars-cov-2, of, the, and, with, in, virus"
38216,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.1,"that, in, virus"
38217,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.1,"this, bat, a, in"
38218,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.1,"sars-cov-2, that, a"
38219,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.1,"sars-cov-2, this, bat"
38220,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.1,"is, that, in, bat"
38221,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.1,"most, of, the, in, that"
38222,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.1,"of, and, revealed, that, with"
38223,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.1,"with, the, of, and, sars-cov"
38224,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.1,"revealed, that, the, and"
38225,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.1,"the, that, of, sars-cov"
38226,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.1,"and, genome, the, sars-cov-2"
38227,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.1,"the, of, sars-cov-2, a, that"
38228,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.1,"the, sars-cov-2, genome"
38229,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.1,"sars-cov-2, of, the, and, with, analysis"
38230,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.1,"a, of, and, that, the, sars-cov-2,, in"
38231,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.1,"are, a, the, of, and, in, that, to"
38232,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.1,"in, the, of, to, that, and, a"
38233,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.1,"the, and, in, similar, to, sars-cov-2,, ratg13"
38234,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.1,"that, are, among, the, genomes, to, in, of, and"
38235,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.1,"s, that, the, and, bat, ratg13"
38236,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.1,"that, the, and, bat, ratg13, viruses"
38237,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.1,"and, sars-cov-2, of"
38238,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.1,"the, of, animal, infectious"
38239,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.1,"pangolins, to, the, of"
38240,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.1,"to, bats, be, the"
38241,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.1,"the, of, most, to"
38242,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.1,"the, of, likely, bats"
38243,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.1,"likely, to, be"
38244,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.1,"the, which, that, of, from"
38245,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.1,"the, of, from, which, sars-cov-2"
38246,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.1,"the, that, of, samples, western, huanan, from"
38247,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.1,"the, results, that, animals, which"
38248,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.1,"provide, that, the, of, for, sars-cov-2"
38249,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.1,"the, results, of, that, sars-cov-2"
38250,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.1,"the, of, that, sars-cov-2, for"
38251,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Bats are natural hosts of many of the known  

coronaviruses",0.1,"of, bats, the"
38252,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Bats are natural hosts of many of the known  

coronaviruses",0.1,"of, the, many"
38253,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.1,"et, that, sars-cov-2, and, from, a"
38254,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.1,"that, from, a, in, to, and"
38255,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.1,"is, that, sars-cov-2, a, coronavirus"
38256,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.1,"coronavirus, from, a, and, sars-cov-2, to, be, in"
38257,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.1,"that, as, may, to, sars-cov-2, in"
38258,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.1,"that, sars-cov-2, and, coronavirus, from, bats"
38259,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.1,"as, similarity, which, sars-cov-2, at, the"
38260,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.1,"the, that, sars-cov-2, genomes, a, and"
38261,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.1,"of, the, was, et, al."
38262,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.1,"the, evidence, that, to, which"
38263,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.1,"to, intermediate, is, pangolin, the"
38264,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.1,"the, from, a, china"
38265,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.1,"a, which, the, strain, from"
38266,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.1,"which, has, the, with"
38267,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.1,"the, and, to, a, of, is"
38268,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.1,"to, the, a, is"
38269,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.1,"of, the, series, a"
38270,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.1,"of, the, been, is, and"
38271,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.1,"to, in, genome"
38272,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.1,"the, genome, that, a"
38273,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.1,"the, of, to, similar, a, with, that, in"
38274,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.1,"the, of, to, strain"
38275,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.1,"coronavirus, a, with, to, in, the"
38276,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.1,"the, coronavirus, a, that, in"
38277,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.1,"of, be, the"
38278,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.1,"the, of, be, that"
38279,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.1,"a, that, the, host"
38280,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.1,"a, host, the"
38281,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.1,"these, the, of, be, that"
38282,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.1,"a, the, that, may"
38283,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.1,"the, of, that, these, a"
38284,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.1,"the, of, suggesting, that, to"
38285,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.1,"that, transmission, of, to, be"
38286,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.1,"the, huanan, seafood, to, of"
38287,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.1,"the, huanan, only, that, of, cases, to, had"
38288,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.1,"the, of, huanan, seafood"
38289,Genetic evidence suggesting otherwise is yet to be presented.,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.1,"suggesting, to, be"
38290,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.1,"a, of, the, virus., that, sars-cov-2"
38291,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.1,"the, sars-cov-2, of, a"
38292,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.1,"sars-cov-2, a, of, that, the"
38293,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.1,"data, that, sars-cov-2"
38294,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.1,"have, to, the"
38295,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.1,"the, of, was, to, and"
38296,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.1,"the, et, sars-cov-2, and"
38297,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.1,"bats, and, was, the"
38298,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.1,"et, of, sars-cov-2, the"
38299,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.1,"bat, the, of, sars-cov-2, et, al.,"
38300,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.1,"sars-cov-2, bat, to, the, in"
38301,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.1,"from, in, the, bat, of"
38302,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.1,"bat, in, the"
38303,The FCS of SARS-CoV-2 was not bioengineered—full stop.,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.1,"the, was"
38304,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.1,"bats, have, been, viruses"
38305,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.1,"in, have, been"
38306,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.1,"viruses, closely, related, have"
38307,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.1,"of, the, at"
38308,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.1,"that, the, of, an"
38309,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.1,"sars-cov-2, between, and"
38310,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.1,"spike, a, pangolin"
38311,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.1,"a, sars-cov-2, ace2"
38312,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.1,"a, receptor, spike, pangolin"
38313,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.1,"in, a, of, the, that, was, for"
38314,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.1,"a, the, of, and, in, on, that"
38315,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.1,"that, taken, the, and"
38316,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.1,"the, of, on, for, in, a, that"
38317,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.1,"the, in, of, and, that, a"
38318,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.1,"of, the, has"
38319,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.1,"in, the, of, sites"
38320,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.1,"for, the, in"
38321,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.1,"viruses, the, been, in, of"
38322,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.1,"a, the, of, sars-cov-2, and"
38323,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.1,"and, sars-cov-2, pangolins, the, between"
38324,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.1,"the, as, origin"
38325,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.1,"indicated, that, the, in, to"
38326,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.1,"the, of, sites, in"
38327,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.1,"that, sars-cov-2, of, related"
38328,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.1,"in, sars-cov-2, ratg13, pangolin, this, that, the"
38329,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","this one jumped from bats origin  

into humans",0.1,"this, from, bats"
38330,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.1,"the, was, a, to, human, than"
38331,"All human coronaviruses have animal origins, namely, natu- 

ral hosts","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.1,"all, human"
38332,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.1,"previous, are, including"
38333,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.1,"a, the, to, human, and"
38334,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.1,"genomic, studies, have, and, the"
38335,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.1,"the, have, human, to, and"
38336,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.1,"to, of, which, have, a"
38337,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.1,"have, a, of, to, and, the"
38338,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.1,"of, the, recent, and, viruses, high, to"
38339,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.1,"a, the, of, virus, china"
38340,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.1,"a, of, the, new"
38341,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.1,"the, of, in, zoonotic"
38342,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.1,"a, of, the, and, zoonotic, in"
38343,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.1,"has, been, in, the, and"
38344,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.1,"the, a, bat, and"
38345,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.1,"of, a, bat, in"
38346,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.1,"also, related, to, bats"
38347,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.1,"the, of, and, sars-cov-2, in"
38348,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.1,"the, for, of, to, and"
38349,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.1,"the, to, for, wild"
38350,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.1,"recent, sars-cov-2, to, in"
38351,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.1,"a, of, and, the, from, bats"
38352,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.1,"as, a, of, the, it, with"
38353,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.1,"a, two, the, of, from"
38354,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.1,"the, from, 96%, with"
38355,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.1,"it, a, the, of, genome, from"
38356,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.1,"a, of, bats, the, as"
38357,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.1,"genome, and, a, the, of"
38358,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.1,"the, for, from, and"
38359,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.1,"sars-cov, sars-cov-2, to"
38360,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.1,"to, sars-cov-2, similarity"
38361,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.1,"sars-cov-2, has, a"
38362,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.1,"pangolins, with, the, sars-cov-2"
38363,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.1,"with, cov, the"
38364,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.1,"the, in, for, a"
38365,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.1,"were, sars-cov-2, in, pangolins"
38366,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.1,"it, sars-cov-2, a"
38367,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.1,"intermediate, host, in, the"
38368,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.1,"a, with, sars-cov-2, intermediate, in, the"
38369,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.1,"sars-cov-2, the, with, similarity"
38370,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.1,"in, the, live, but, positive, animal, and, of, both, sars-cov-2, animals"
38371,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.1,"for, the, sars-cov, civet, positive, of, bat, wild, high, and, with"
38372,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.1,"the, to, bat, of"
38373,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.1,"a, the, of, bat, yunnan"
38374,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.1,"be, the, of, bat"
38375,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.1,"a, of, to, be, may"
38376,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.1,"of, viruses, to, the"
38377,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.1,"the, of, that, viruses"
38378,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.1,"available, to, the, sars-cov-2"
38379,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.1,"genome, the, virus, december, and"
38380,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.1,"genome, sars-cov-2, and, the, virus"
38381,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.1,"the, sars-cov-2, genome, and"
38382,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.1,"sars-cov-2, to, the, and"
38383,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.1,"to, the, been, by, and"
38384,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.1,"the, sars-cov-2, to, is, in"
38385,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.1,"the, sars-cov-2, in, is"
38386,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.1,"the, a, and, to, of, with"
38387,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.1,"a, virus, to, not, of, and, more"
38388,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.1,"a, of, that, the, from, in, bats"
38389,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.1,"is, that, sars-cov-2, from, a, the, in"
38390,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.1,"the, coronavirus, from, with, sars-cov-2"
38391,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.1,"the, pangolin, is, to, intermediate"
38392,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.1,"is, that, sars-cov-2, a, the, of, from"
38393,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.1,"in, a, with, sars-, to, sars-cov-2, the"
38394,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.1,"past, that, a, of, the, is"
38395,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.1,"of, a, analysis, that, the, to"
38396,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.1,"is, the, coronavirus, to, in, of"
38397,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.1,"genome, the, and, identity, sars-cov-2"
38398,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.1,"the, with, from, sars-cov-2"
38399,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.1,"the, with, sars-cov-2, were, collected"
38400,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.1,"of, sars-cov-2, from, the, which"
38401,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.1,"rhinolophus, the, of, and, two, in"
38402,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.1,"sars-cov-2, with, a"
38403,"with the first case being linked to  

a seafood market","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.1,"with, a"
38404,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.1,"with, a, sars-cov-2"
38405,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.1,"a, sars-cov-2, with"
38406,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.1,"a, sars-cov-2, with, coronavirus"
38407,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.1,"a, of, in, with, sars-cov-2"
38408,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.1,"that, sars-cov-2, a, virus, in"
38409,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.1,"a, of, virus, in, with, that"
38410,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.1,"that, with, in, a, of"
38411,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.1,"virus, that, a"
38412,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.1,"has, of, with, sars-cov-2"
38413,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.1,"in, a, with, sars-cov-2, genome"
38414,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.1,"a, in, with, sars-cov-2, bat"
38415,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.1,"a, of, in, horseshoe"
38416,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.1,"that, a, of, virus"
38417,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.1,"a, similarity, of, sars-cov-2, in"
38418,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.1,"that, sars-cov-2, in, with"
38419,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.1,"that, similarity, sars-cov-2, bat"
38420,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.1,"sars-cov-2, is, that"
38421,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.1,"the, sars-cov-2, that"
38422,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.1,"sars-cov-2, the, that, is"
38423,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.1,"human, from, the, virus"
38424,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.1,"the, of, zoonotic, host"
38425,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.1,"of, a, the, by"
38426,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.1,"a, zoonotic, that, of"
38427,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.1,"the, of, that, zoonotic"
38428,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.1,"a, of, the, has, been, that"
38429,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.1,"the, host, of, not"
38430,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.1,"is, not, a, the, by"
38431,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.1,"of, and, that, the, group"
38432,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.1,"is, that, sars-cov-2, the, sequence"
38433,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.1,"phylogenetic, the, of, sars-cov-2"
38434,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.1,"analysis, the, and"
38435,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.1,"is, the, sequence, of"
38436,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.1,"of, sars-cov-2, in, to"
38437,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.1,"the, to, of, has"
38438,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.1,"to, sars-cov-2, in, the, of"
38439,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.1,"also, as, the, and, in, to, an"
38440,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.1,"in, the, to, sars-cov-2, has, and"
38441,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.1,"that,, to, in, sars-cov-2, the, and"
38442,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.1,"sars-cov-2, also, to, and, the"
38443,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","bats are also important reservoir species for a great 

range of coronaviruses",0.1,"bats, of, species"
38444,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","bats are also important reservoir species for a great 

range of coronaviruses",0.1,"of, are, coronaviruses, for"
38445,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","bats are also important reservoir species for a great 

range of coronaviruses",0.1,"also, species, are, bats, a"
38446,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","bats are also important reservoir species for a great 

range of coronaviruses",0.1,"bats, are, important, of, a"
38447,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.1,"the, from, in, bats"
38448,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.1,"and, to, those, of, the"
38449,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.1,"ace2, and, the, in, of"
38450,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.1,"of, and, species, in, the"
38451,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.1,"the, from, and, to, of"
38452,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.1,"the, and, in, to, ace2, of"
38453,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.1,"from, and, with, the"
38454,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.1,"the, sequence, from, bat, and"
38455,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.1,"that, protein, of"
38456,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.1,"in, amino, acid, with"
38457,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.1,"amino, acid, with, sars-cov-2, be, in, the"
38458,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.1,"sars-cov-2, by, at, the, in"
38459,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.1,"this, to, that, be"
38460,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.1,"the, from, in, horseshoe, bats"
38461,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.1,"the, and, in, ratg13, similar, to, sars-cov-2,"
38462,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.1,"from, bats, to, is, found, in, the"
38463,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.1,"the, by, from, at, and, to"
38464,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.1,"the, to, in, one, horseshoe, is, most, bats, by, and"
38465,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.1,"to, and, is, similar, ratg13, in"
38466,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.1,"to, the, for, in"
38467,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.1,"the, amino, acid, use"
38468,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.1,"to, ace2, the, in"
38469,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.1,"as, the, in, with, sars-cov-2"
38470,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.1,"the, in, rbd, sars-cov-2"
38471,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.1,"the, in, sars-cov-2, with"
38472,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.1,"that, sars-cov-2, is, to, be, the"
38473,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.1,"the, of, that, to, such, as, and"
38474,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.1,"the, et, that, sars-cov-2, natural, and"
38475,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.1,"that, the, be, of, these"
38476,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.1,"the, to, as, of, sars-cov-2, and"
38477,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.1,"that, the, of, as, can, single, to"
38478,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.1,"it, is, that, sars-cov-2, of"
38479,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.1,"natural, of, the, to, that, such, can"
38480,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.1,"and, in, the, of, animal, hosts"
38481,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.1,"the, intermediate, animal, of, as"
38482,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.1,"as, the, or, with, of, for, and"
38483,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.1,"with, that, the, of, as, sars-cov-2, and"
38484,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.1,"in, the, of, as, intermediate, a, that, and"
38485,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.1,"with, the, and, for, of, a, or, that, in, sars-cov-2, animal"
38486,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.1,"sars-cov-2, a, that, with, the, for"
38487,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.1,"that, the, in, to, with, and"
38488,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.1,"that, sars-cov-2, the, and, humans"
38489,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.1,"the, sars-cov-2, between, pangolins, and"
38490,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.1,"the, to, sars-cov-2, be, in"
38491,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.1,"in, the, intermediate, that, humans, to, and, than"
38492,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.1,"in, the, rbd, to, sars-cov-2, that"
38493,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.1,"has, been, the, in, however,, and"
38494,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.1,"in, the, may, have, been"
38495,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.1,"the, and, has, been, in"
38496,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.1,"in, through, it, that, the, and"
38497,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.1,"obtained, early, in, the, these, and"
38498,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.1,"laboratory, and, to, the, a"
38499,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.1,"mice, and, the, was, in"
38500,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.1,"the, and, that, a, in, to"
38501,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.1,"to, a, in, mice, and"
38502,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.1,"a, in, that, contrast, the, reported, to"
38503,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.1,"ace2, a, sars-cov-2"
38504,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.1,"the, amino, acid, to"
38505,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.1,"and, the, of, species, by"
38506,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.1,"of, sars-cov-2, humans, and, to"
38507,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.1,"for, the, of, is, and, it"
38508,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.1,"the, of, sars-cov-2, is, for"
38509,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.1,"the, as, a"
38510,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.1,"a, to, the, as, intermediate"
38511,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.1,"the, as, a, from, to"
38512,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.1,"to, the, of, evidence, supporting, that"
38513,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.1,"of, to, the, who, that"
38514,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.1,"the, of, was, a, that, to, and"
38515,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.1,"to, were, in, the"
38516,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.1,"the, sars-cov-2, and, at, in, were"
38517,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.1,"the, species, in, and"
38518,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.1,"several, species, the"
38519,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.1,"and, in, were, to, the, sars-cov-2"
38520,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.1,"sequences, that, of, in, intermediate"
38521,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.1,"this, the, was, in, of"
38522,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.1,"the, market, that, in, of, 2020, identification, early"
38523,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.1,"from, in, at, the, of"
38524,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.1,"the, sequences, this, of"
38525,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.1,"sars-cov-2, to, found, in, bat"
38526,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.1,"sars-cov-2, to, coronavirus"
38527,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.1,"to, banal, in"
38528,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.1,"sars-cov-2, with, bat"
38529,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.1,"the, for, of, that, from"
38530,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.1,"the, from, in, market"
38531,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.1,"that, sars-cov-2, from, in"
38532,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.1,"that, of, the, for, sars-cov-2"
38533,"Bats have been reported as being the rich source of 

coronaviruses","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.1,"bats, been, the, of, coronaviruses"
38534,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.1,"a, of, the, with, that, bats, could"
38535,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.1,"the, that, of, has, been, a"
38536,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.1,"the, evidence, from, that, to, and"
38537,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.1,"of, that, it, to, the, and"
38538,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.1,"a, of, from, in, coronaviruses, sars-cov-2"
38539,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.1,"the, for, of, host"
38540,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.1,"of, the, for, sars-cov-2."
38541,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.1,"sars-cov-2, at, the, of, covid-19"
38542,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.1,"that, the, virus, from, at, a"
38543,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.1,"the, of, a, it, genome, from"
38544,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.1,"that, of, from, is, a, sars-cov-2, the"
38545,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.1,"pandemic, of, natural, the, virus"
38546,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.1,"a, to, the, natural, of, or"
38547,"natural selection in humans  

following zoonotic transfer","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.1,"natural, in, zoonotic"
38548,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.1,"the, of, a, sars-cov-2, or"
38549,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.1,"of, the, sars-cov-2, in, is"
38550,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.1,"to, sars-cov-2, the, virus, of"
38551,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.1,"of, in, horseshoe, bats"
38552,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.1,"the, in, of, and, china"
38553,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.1,"and, in, most, the, of"
38554,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.1,"of, the, or, most"
38555,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.1,"bats, in, the, south, china, or, and, of, are"
38556,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.1,"in, china, the, of, and"
38557,"with the first case being linked to  

a seafood market","Bats are the second  

largest order of mammals, with over 1,230 species.",0.1,"with, the"
38558,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Bats are the second  

largest order of mammals, with over 1,230 species.",0.1,"with, of, the"
38559,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.1,"many, such, bat, have, to, and"
38560,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.1,"the, sars-cov-2, beta, of"
38561,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.1,"sars-cov-2, coronaviruses, the"
38562,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.1,"and, as, of"
38563,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.1,"the, as, and"
38564,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.1,"viruses, the, and"
38565,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.1,"for, the, of, and, sars, as"
38566,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.1,"viruses, the, bats, of, and"
38567,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.1,"and, bat, as, of"
38568,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.1,"as, and, the, of, to, sars-cov-2"
38569,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.1,"to, the, bats, as, and, reservoir, of, species, horseshoe, (rhinolophus"
38570,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.1,"horseshoe, bats, to, of, sars-cov-2, and"
38571,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.1,"bat, to, in, the, southern, china, all, and, including"
38572,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.1,"are, and, related, to, that, in"
38573,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.1,"the, and, viruses, other"
38574,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.1,"to, the, in, virus"
38575,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.1,"virus, to, the, for"
38576,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.1,"in, the, to, virus"
38577,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.1,"bat, of, the, in"
38578,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.1,"a, in, this, bat"
38579,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.1,"in, species, of, and, the"
38580,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.1,"are, a, in, the, bat, and"
38581,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.1,"and, the, of, by, a"
38582,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.1,"the, in, of, similar, this"
38583,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.1,"by, in, the, southeast"
38584,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.1,"are, the, suggesting, by, in, this, of, and"
38585,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.1,"the, between, and, bat, same"
38586,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.1,"the, genetic, of, to, that, bat"
38587,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.1,"single, as, the, of, to, can, that"
38588,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.1,"the, of, species, that, a, in, as, to"
38589,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.1,"a, that, the, also, and, for, to, which, is"
38590,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.1,"the, and, of, new, virus, is, to, that, bat"
38591,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.1,"a, in, the, with, that, similar, to, of"
38592,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.1,"viruses, similar, to, the, in, bats, of, and, that, a"
38593,"with the first case being linked to  

a seafood market","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.1,"with, to, a"
38594,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.1,"known, to, sars-cov-2, of"
38595,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.1,"a, of, to, sars-cov-2"
38596,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.1,"a, sars-cov-2, with, of, from"
38597,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.1,"a, of, sars-cov-2, with"
38598,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.1,"have, of, to, a, which"
38599,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.1,"a, of, to, which"
38600,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.1,"of, sars-cov-2, to, which"
38601,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.1,"the, sars-cov-2, is, bat"
38602,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.1,"the, similarity, sars-cov-2, at, which, as"
38603,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.1,"he, banal, is, the"
38604,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.1,"the, approximately, as, at, similar, to, by, coronavirus, is, related"
38605,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.1,"is, the, similarity, sars-cov-2"
38606,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.1,"and, sars-cov-2, in, to, which"
38607,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.1,"and, are, to, the, other, a"
38608,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.1,"other, the, which, to, and"
38609,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.1,"the, in, and, to, at, a"
38610,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.1,"and, by, with, the, was, in"
38611,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.1,"sars-, to, a, in, with, sars-cov-2, the"
38612,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.1,"a, in, genome, with, sars-cov-2"
38613,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.1,"a, in, with, by, the, to, closely, related"
38614,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.1,"the, are, to, in, a, with, was, by, and, other"
38615,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.1,"and, with, to, at, the, in, team, a, was"
38616,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.1,"in, similar, at, with, sars-cov-2, the"
38617,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.1,"to, and, it, similar, related, in"
38618,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.1,"are, also, the, of, their, to"
38619,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.1,"of, sars-cov-2, closely, related"
38620,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.1,"by, the, their"
38621,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.1,"of, the, sars-cov-2, viruses"
38622,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.1,"when, the, are, sars-cov-2"
38623,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.1,"on, the, by, that, through, natural, a"
38624,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.1,"the, in, on, that, for, a, of"
38625,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.1,"is, that, through, of, a, related"
38626,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.1,"that, the, virus, in, to, through, of"
38627,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.1,"natural, of, the, in, a, similar, to, that"
38628,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.1,"to, with, the, of"
38629,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.1,"the, that, of, human, with"
38630,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.1,"that, through, of"
38631,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","This suggests that the BANAL series may be able to directly infect  

humans.",0.1,"that, to, directly"
38632,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.1,"human, to, in, viruses"
38633,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.1,"viruses, that, to, human"
38634,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.1,"banal, to, in"
38635,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.1,"in, viruses, to"
38636,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.1,"the, in, from"
38637,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.1,"the, in, from, of"
38638,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.1,"the, more, of, in"
38639,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.1,"he, is, banal, the"
38640,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.1,"from, is, the"
38641,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.1,"viruses, a, of"
38642,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.1,"have, the, at, of"
38643,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.1,"the, a, series, of"
38644,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.1,"the, at, of"
38645,"preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.1,"of, viruses, their"
38646,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.1,"a, of, the, at, have"
38647,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.1,"the, of, at, a"
38648,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.1,"the, a, and, viruses"
38649,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.1,"the, and, which, a"
38650,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.1,"a, the, and, at, two, which, viruses"
38651,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.1,"a, the, to, have"
38652,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.1,"the, is, same, and"
38653,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.1,"and, to, closely, related, sars-cov-2,, the, is"
38654,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.1,"amino, acid, of"
38655,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.1,"animal, to, a, human"
38656,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.1,"a, to, mice, and, in"
38657,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.1,"virus, bat, as, of"
38658,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.1,"strain, the, to, of"
38659,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.1,"the, of, highest, by"
38660,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.1,"first, and, was"
38661,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.1,"most, the, sars-cov-2, is, to"
38662,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.1,"be, sars-cov-2, to, the, in"
38663,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.1,"of, covid-19, the, across"
38664,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.1,"viral, of, the, is"
38665,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.1,"is, the, its, of"
38666,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.1,"other, coronaviruses, the, to, and"
38667,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.1,"a, bat, in, with, sars-cov-2"
38668,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.1,"that,, in, to, the, sars-cov-2, and"
38669,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.1,"and, are, bat, a, in, the"
38670,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.1,"it, in, the, and, that, through"
38671,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.1,"the, first, in, that"
38672,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.1,"and, in, be, that, the, is, sars-cov-2"
38673,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.1,"that, the, zoonotic"
38674,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.1,"the, early, that"
38675,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.1,"that, the, with"
38676,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.1,"that, were, the, huanan, seafood, and"
38677,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.1,"the, of, and, suggesting, that, these, a, covid-19"
38678,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.1,"a, of, the, was, to, with"
38679,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.1,"of, to, the, huanan, seafood"
38680,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.1,"the, of, to, with, and, a"
38681,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.1,"from, of, to, and, the"
38682,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.1,"at, the, and, from, to, by"
38683,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.1,"a, the, was, to, and"
38684,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.1,"was, from, to, and"
38685,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.1,"of, the, and, a, with"
38686,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.1,"the, that, was, to, have, sars, in, different, than, of, or, not, into, at"
38687,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.1,"all, have, a, zoonotic, origin,, that, different, of, to"
38688,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.1,"a, for, the, of, virus, in, with, that, to"
38689,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.1,"that, the, with, in, market, or, a, of"
38690,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.1,"a, reported, that, the, to, in, contrast"
38691,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.1,"in, by, a, with, closely, related, to, the"
38692,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.1,"the, of, infected, that, were, to, animal, market, in, is"
38693,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.1,"a, of, the, from, by, that, and, at, least, two, in, were"
38694,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.1,"related, coronavirus, to, as, by, is, approximately, similar, at, the"
38695,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.1,"in, the, of, a, was, first, and, wildlife, market"
38696,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.1,"to, humans, from, and, with, the, of"
38697,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.1,"as, the, for, of, sars, and"
38698,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.1,"that, the, of, species, in, as, a, to"
38699,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.1,"the, that, of, human, with, and, in, collected"
38700,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.1,"that, were, to, found, in, and, from"
38701,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.1,"from, a, and, with, whether, intermediate, to, in, the"
38702,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.1,"in, the, of, were, as, intermediate"
38703,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.1,"the, of, infected, that, were, to, in"
38704,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.1,"the, outbreak, was, in, humans, from"
38705,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.1,"the, to, humans, from, in, of, found"
38706,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.1,"the, was, to, human, than, a"
38707,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.1,"in, a, of, and, that, the, as, intermediate"
38708,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.1,"that, and, intermediate, to, humans, than, the, in"
38709,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.1,"that, the, of, a, was, and, to"
38710,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.1,"indicated, that, the, from, a, in, to, humans, and, further"
38711,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.1,"the, horseshoe, bats, species, to, as, reservoir, of, (rhinolophus, and"
38712,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.1,"scientists, coronaviruses, of, a, large, viruses, in, horseshoe, bats"
38713,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.1,"that, civets, were, bats, in, the, south, china, a, or, and, large, of, viruses"
38714,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.1,"with, the, and, for, of, a, to, team, that, in, this, sars, live, by, at"
38715,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.1,"the, virus, for, a, of, to, from, and, horseshoe, bat"
38716,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.1,"the, to, all, bat, in, southern, china, and, including"
38717,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.1,"of, the, bat, a, from, animal, species, as, or, for"
38718,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.1,"the, are, or, of, bats, in, and, south, china"
38719,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.1,"the, of, a, large, viruses, in, that, bats, civets, and, or, were, china, south"
38720,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.1,"bats, and, may, the, from, or, in, markets, china"
38721,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.1,"as, a, of, the, in, was, is, to, infected, with"
38722,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.1,"on, and, that, is, most, likely, by, bats, of"
38723,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.1,"the, and, in, horseshoe, bats, is, most, one, to, by"
38724,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.1,"was, in, by, a, with, other, and, are, to, the"
38725,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.1,"and, that, a, of, the, virus, is, most, likely"
38726,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.1,"of, the, in, and, that, a, group, with, viruses"
38727,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.1,"other, that, are, to, and, a, on, the, of"
38728,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.1,"was, the, with, wuhan, in, seafood, market, a, of"
38729,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.1,"was, in, a, team, with, and, to, at, the"
38730,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.1,"that, the, of, market, in, to, were, not, have, a, by"
38731,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.1,"only, of, cases, to, the, huanan, that, had"
38732,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.1,"the, identification, of, in, market, early, 2020, that"
38733,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.1,"the, of, a, to, in, markets, and, market, were"
38734,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.1,"a, of, the, this, by, that, early, sars-cov-2, and, at, in, were"
38735,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.1,"sars-cov-2, in, a, of, animal, and, that, the, with, or, for"
38736,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.1,"the, team, for, to, a, live, that, with, this, and, by, sars, in, of, at"
38737,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.1,"the, 21, on, and, were, in, of, a, which, to, positive"
38738,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.1,"the, covid-19, to, and, suggesting"
38739,zoonotic origins of SARS-CoV-2 by natural evolution,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.1,"zoonotic, of, natural"
38740,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.1,"and, a, to, the, natural, of"
38741,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.1,"evidence, the, natural, of, and, between"
38742,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.1,"the, and, some, to, a, in"
38743,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.1,"to, the, a, zoonotic"
38744,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.1,"at, that, the, a"
38745,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.1,"that, a, animal, and"
38746,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.1,"that, are, the, and, in, markets"
38747,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.1,"the, to, this, that, in"
38748,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.1,"at, this, the, that, are"
38749,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.1,"a, in, the, that, animal"
38750,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.1,"of, and, are, known, the"
38751,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.1,"of, the, genomic, that, is"
38752,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.1,"that, the, of, with, human"
38753,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.1,"the, of, and, that, collected, in, human, with"
38754,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.1,"the, in, of, and, that, these, covid-19"
38755,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.1,"that, the, from, a, seafood, in, and"
38756,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.1,"that, the, in, and, seafood, market,, of"
38757,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.1,"the, of, from, then, zoonotic, by, a"
38758,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.1,"that, of, samples, from, the, western, huanan"
38759,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.1,"evidence, that, the, of, all, and, in, between"
38760,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.1,"a, the, pandemic, that, sars-cov-2, into, humans"
38761,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.1,"sars-cov-2, a, that, the, with, for"
38762,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.1,"is, that, the, natural"
38763,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.1,"most, the, with, wildlife"
38764,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.1,"found, to, that, the, is, natural, sars-cov-2"
38765,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","expended to make the simple point 

that COVID-19 had a natural origin.",0.1,"that, natural, to, the"
38766,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","expended to make the simple point 

that COVID-19 had a natural origin.",0.1,"a, the, that"
38767,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","expended to make the simple point 

that COVID-19 had a natural origin.",0.1,"the, that, covid-19"
38768,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.1,"to, that, and, including, sars-cov-2"
38769,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.1,"that, were, from, and"
38770,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.1,"coronaviruses, to, that, and"
38771,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.1,"that, sars-cov-2, to, coronaviruses"
38772,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.1,"sars-cov-2, and, to, bats"
38773,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.1,"pangolins, were, sars-cov-2, in"
38774,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.1,"and, were, that, from, found, in, to"
38775,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.1,"from, rhinolophus, to, in, that"
38776,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.1,"from, rhinolophus, in, china"
38777,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.1,"from, the, also"
38778,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.1,"from, as, the"
38779,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.",0.1,"and, host, zoonotic"
38780,"atural  

selection in an animal host before zoonotic  

transfer;","The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.",0.1,"host, zoonotic"
38781,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.1,"to, the, of, and, which"
38782,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.1,"the, of, to, a"
38783,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.1,"the, a, and, to"
38784,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.1,"their, in, which, and"
38785,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.1,"the, of, viruses, to"
38786,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.1,"to, of, which, a"
38787,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.1,"of, a, to, and, the, in"
38788,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.1,"the, of, to, natural, a"
38789,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.1,"to, of, and, in, their"
38790,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.1,"the, to, which, a"
38791,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.1,"a, of, to, and, the"
38792,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.1,"sars-cov-2, was, a, in, before"
38793,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.1,"was, and, in, a"
38794,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.1,"in, sars-cov-2, has, and, a"
38795,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.1,"was, in, a, and, sars-cov-2"
38796,"The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.1,"zoonotic, and, host"
38797,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.1,"in, an, sars-cov-2, was"
38798,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.1,"and, a, natural, origin"
38799,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.1,"sars-cov-2, was, and"
38800,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.1,"and, a, sars-cov-2, in, an"
38801,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.1,"in, and, sars-cov-2, a"
38802,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.1,"sars-cov-2, and, a, origin"
38803,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.1,"in, sars-cov-2, and"
38804,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.1,"sars-cov-2, the, its, in"
38805,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.1,"in, a, sars-cov-2, with, that"
38806,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.1,"sars-cov-2, bat, identity, the"
38807,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.1,"this, is, a, of, the"
38808,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.1,"that, is, evidence, a, to"
38809,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.1,"sars-cov-2, the, not, that, of, is"
38810,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.1,"of, sars-cov-2, to, ace2, the"
38811,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.1,"sars-cov-2, of, is, that"
38812,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.1,"sars-cov-2, is, a, that, coronavirus"
38813,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.1,"of, that, sars-cov-2, related"
38814,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.1,"a, sars-cov-2, it"
38815,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.1,"of, it, that, sars-cov-2, is"
38816,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.1,"of, related, is, a, through, that"
38817,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.1,"through, that, of"
38818,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.1,"a, is, that, it"
38819,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.1,"it, of, that, sars-cov-2, a, laboratory"
38820,"The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.","atural  

selection in an animal host before zoonotic  

transfer;",0.1,"zoonotic, host"
38821,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","atural  

selection in an animal host before zoonotic  

transfer;",0.1,"an, in"
38822,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","natural selection in humans  

following zoonotic transfer",0.1,"zoonotic, humans, in"
38823,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","natural selection in humans  

following zoonotic transfer",0.1,"following, in, humans"
38824,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","natural selection in humans  

following zoonotic transfer",0.1,"natural, zoonotic, in"
38825,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.1,"hosts, the, of, is"
38826,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.1,"to, the, for, of"
38827,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.1,"of, to, the, its"
38828,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.1,"bats, hosts, of, to, that, as"
38829,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.1,"is, from, which, it"
38830,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.1,"is, that, a, in"
38831,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.1,"that, may, spike, to"
38832,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.1,"the, that, not, from, a"
38833,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.1,"that, the, may, a"
38834,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.1,"that, to, in, rhinolophus, from"
38835,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.1,"it, is, that, a"
38836,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.1,"suggests, that, the, in, to"
38837,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.1,"to, the, from, a, bind"
38838,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Malayan pangolins (Manis javanica)  

illegally imported into Guangdong province  

contain coronaviruses similar to SARS- 

CoV-22",0.1,"pangolins, (manis, javanica), guangdong"
38839,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.1,"all, that, sars-cov-2, natural, is"
38840,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.1,"that, the, natural, of, all, in, for"
38841,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.1,"the, to, this, that, in, of"
38842,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.1,"this, is, the, sars-cov-2, that, for"
38843,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.1,"that, the, protein, of, pangolin, to"
38844,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.1,"the, which, of, and"
38845,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.1,"the, by, a, and, of"
38846,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.1,"a, by, shows, that, the, of"
38847,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.1,"the, into, humans,, of"
38848,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.1,"through, that, the, jumped, a"
38849,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.1,"that, of, is, a, sars-cov-2, the"
38850,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.1,"of, it, is, possible, that"
38851,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.1,"the, of, that, in, similar, to"
38852,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.1,"this, of, similar, in, the"
38853,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.1,"sars-cov-2, was, in, an"
38854,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.1,"t, that, sars-cov-2, to"
38855,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.1,"the, sars-cov-2, this, of"
38856,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.1,"the, and, of, coronaviruses, these"
38857,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.1,"the, a, coronaviruses, from, and, with"
38858,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.1,"these, and, from, the, of"
38859,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.1,"the, identical, of, and, from"
38860,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.1,"sars-cov-2, a, from, and, the"
38861,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.1,"the, of, sars-cov-2, or, a"
38862,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.1,"the, these, with, of, sars-cov-2, or"
38863,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.1,"provides, and, pangolins, sars-cov-2"
38864,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.1,"the, more, of, sars-cov-2"
38865,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.1,"the, of, and, pangolins, more, sars-cov-2"
38866,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.1,"the, of, sars-cov-2, is, that, not"
38867,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.1,"the, that, sars-cov-2, of, and"
38868,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","In the 

case of MERS, dromedaries were the principal host.",0.1,"of, the, were"
38869,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","In the 

case of MERS, dromedaries were the principal host.",0.1,"the, in, were, of"
38870,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.1,"who, to, in, animals, and"
38871,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.1,"that, genome, bat, the"
38872,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.1,"the, of, backbone, that, coronavirus, a"
38873,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.1,"the, coronavirus, a, that, in, nature"
38874,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.1,"that, the, this, novel, coronavirus"
38875,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.1,"and, human, that, a, of, the"
38876,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.1,"in, the, more, to"
38877,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.1,"the, to, and, sequence"
38878,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.1,"of, the, in, and, showed"
38879,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.1,"of, the, sars-cov, and"
38880,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.1,"the, bats, more, than"
38881,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.1,"that, belongs, to, the"
38882,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.1,"the, which, that, evidence, to"
38883,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.1,"evidence, to, from, the, and, that"
38884,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.1,"analysis, that, the, covid-19"
38885,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.1,"to, the, and, evidence, that"
38886,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",The COVID-19 most likely developed from bat origin coronaviruses,0.1,"bat, the, from"
38887,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",The COVID-19 most likely developed from bat origin coronaviruses,0.1,"the, from"
38888,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.1,"origin, of, covid-19, for, ace2, a, or, that, the"
38889,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.1,"animal, hosts, the, of, is"
38890,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.1,"bat, a, as, from, animal, for, the, or, of, species"
38891,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.1,"the, of, that, these, receptor"
38892,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.1,"the, that, hosts, for, covid-19"
38893,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.1,"on, have, is, of"
38894,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.1,"these, have, a, of"
38895,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.1,"of, a, which, covs."
38896,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.1,"a, of, which, is, viruses"
38897,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.1,"that, the, sequence, of"
38898,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.1,"that, the, of, viruses"
38899,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.1,"amino, acid, the, use"
38900,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.1,"the, of, ,, that"
38901,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.1,"of, that, the, receptor, these"
38902,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.1,"to, seafood, and, in"
38903,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.1,"humans, to, bats, the"
38904,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.1,"the, of, in, virus, to, through, that"
38905,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.1,"and, the, seafood, market,, that, of, in"
38906,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.1,"to, in, the, suggests, that"
38907,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.1,"intermediate, and, to, the, of, that, in"
38908,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.1,"in, bats, to, that, of, and"
38909,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.1,"zoonotic, and, in"
38910,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.1,"and, to, zoonotic"
38911,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.1,"all, to, are"
38912,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.1,"are, to, that"
38913,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",Bats are hosts of many coronaviruses,0.1,"are, of, bats"
38914,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.1,"to, viruses, in"
38915,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.1,"an, animal, intermediate"
38916,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.1,"to, the, emerged"
38917,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.1,"the, market, in"
38918,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.1,"in, to, the, is"
38919,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.1,"is, to, the, be"
38920,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.1,"in, be, the"
38921,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.1,"the, which, was, in"
38922,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.1,"the, which, that, of"
38923,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.1,"in, the, of, that, most"
38924,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.1,"the, that, of, been"
38925,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.1,"the, of, which, in"
38926,"The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.1,"the, that, early"
38927,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.1,"have, in, the, which"
38928,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.1,"the, of, that, to, it"
38929,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.1,"that, to, bat, the"
38930,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.1,"the, most, for, of"
38931,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.1,"the, that, was, to, most, is, of, it, and"
38932,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.1,"to, the, and, is, for"
38933,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.1,"of, the, sars-like, bat, that"
38934,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.1,"to, of, the, and, it, that"
38935,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.1,"the, for, of, sars-cov-2."
38936,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.1,"bat, is, to"
38937,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.1,"to, the, and, that, for"
38938,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.1,"have, been, to, a, and, in, china"
38939,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.1,"in, the, rhinolophus, genus, and"
38940,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.1,"and, the, of, to, similar, viruses, a, bats, that, in"
38941,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.1,"a, of, the, that, covid-19, and, these, suggesting"
38942,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.1,"the, that, of, covid-19, and, these, in"
38943,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.1,"of, the, in, a, similar, to, that"
38944,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.1,"the, of, two, rhinolophus, and, in"
38945,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.1,"the, between, and, of, evidence, natural"
38946,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.1,"markets, are, and, in, the, that"
38947,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.1,"evidence, in, the, and, that, of, all, between"
38948,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.1,"in, the, all, that, for, of, natural"
38949,"preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.1,"evidence, that, of, sars-cov-2-like, viruses"
38950,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.1,"that, natural, the, of, and, evidence"
38951,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.1,"the, which, be, found, in, probably"
38952,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.1,"that, the, virus, be"
38953,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.1,"with, be, the, virus"
38954,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.1,"results, that, the, which, animals"
38955,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.1,"the, in, that, which"
38956,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.1,"the, that, in, with, animals"
38957,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.1,"of, the, huanan, seafood"
38958,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.1,"the, of, in, market"
38959,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.1,"of, in, the, china"
38960,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.1,"that, not, it, was, to, in"
38961,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.1,"the, of, first, in, this, to"
38962,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.1,"the, has, to, that, of"
38963,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.1,"the, that, in, animals, with"
38964,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.1,"to, have, in, the, with"
38965,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.1,"the, of, that, to, with"
38966,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.1,"the, of, bats, as, a"
38967,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.1,"a, in, china, the, of, bats"
38968,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.1,"bats, the, as, a"
38969,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.1,"of, the, that, or"
38970,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.1,"is, natural, that, the"
38971,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.1,"from, in, bat, species, china"
38972,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.1,"is, bat, viruses,, the"
38973,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.1,"in, rhinolophus, china, from"
38974,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.1,"the, viruses, in, or, bats"
38975,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.1,"can, transmission, bat, bats, of, and, some"
38976,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.1,"the, and, bat, or, of"
38977,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.1,"with, and, to, in, of"
38978,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.1,"of, in, their, and, to"
38979,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.1,"in, can, be, and, of"
38980,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.1,"bats, the, to, be, and"
38981,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.1,"is, from, the"
38982,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.1,"the, is, from"
38983,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.1,"from, the, between, and"
38984,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.1,"bats, and, species, the"
38985,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.1,"was, the, and, host, by"
38986,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.1,"was, and, bats, the"
38987,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.1,"intermediate, host, the, in"
38988,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.1,"an, was, the, previous"
38989,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.1,"a, are, to, bat, of, from"
38990,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.1,"of, virus, more, not, to, and, a"
38991,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.1,"some, can, of, and, bats, transmission, bat"
38992,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.1,"of, a, virus, to, bat, and"
38993,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.1,"are, to, and, a, on, of"
38994,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.1,"bats, are, virus, be, in, to"
38995,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.1,"are, in, to, of, the, which, has, bats, and"
38996,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.1,"into, or, to, and, may, then"
38997,"bats are also important reservoir species for a great 

range of coronaviruses","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.1,"bats, are, also, species, a"
38998,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.1,"was, the, of, identical, to, a, sars-cov"
38999,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.1,"of, a, to, markets, and, the, market, were, in"
39000,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.1,"the, in, of, and"
39001,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.1,"of, the, market, in"
39002,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.1,"a, the, first"
39003,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.1,"in, the, first, of, market, was, wildlife, a, and"
39004,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.1,"in, the, of, was, a, and"
39005,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.1,"and, the, between, in"
39006,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.1,"and, have, from, the, of"
39007,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.1,"sars-cov-2, from, and, is, viruses, in"
39008,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.1,"the, is, of, and, from"
39009,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.1,"sars-cov-2, is, from, and, the"
39010,hese close genetic relations suggest that they all have their ecological origin in bat populations,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.1,"have, their, origin, in"
39011,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.1,"the, is, of, and, been"
39012,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.1,"the, is, in, sars-cov-2"
39013,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.1,"the, and, is, of, origin"
39014,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.1,"the, of, origin, and, is"
39015,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.1,"of, the, in, is, with, sars-cov-2"
39016,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.1,"the, of, is, virus, in, with, receptor"
39017,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.1,"on, receptor, binding, is, of"
39018,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.1,"the, of, in, from, at"
39019,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.1,"in, with, similar, sars-cov-2, at, the"
39020,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.1,"viral, of, the, virus, is"
39021,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.1,"of, the, in, sars-cov-2, with"
39022,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.1,"s, the, sars-cov-2, guangdong, is"
39023,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.1,"sars-cov-2, similar, on, the, of"
39024,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.1,"the, binding, in, sars-cov-2"
39025,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","t some virus detected in pangolins 

were capable of infecting humans.",0.1,"were, virus, in"
39026,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.1,"by, et, al., in, china, were, found"
39027,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.1,"a, positive, on, and, were, to, 21, of, which, in, the"
39028,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.1,"southeast, by, in, the"
39029,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.1,"the, by, their"
39030,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.1,"by, in, the, were, bats"
39031,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.1,"in, of, which"
39032,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.1,"of, were, in, which"
39033,"atural  

selection in an animal host before zoonotic  

transfer;","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.1,"in, an"
39034,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.1,"the, in, from, bats"
39035,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.1,"from, bats, in, the, china, or, and, may, markets"
39036,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.1,"and, (or, the, between, in"
39037,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.1,"between, and, in, the"
39038,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.1,"the, and, of, that"
39039,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.1,"the, a, that, animals, and"
39040,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.1,"the, and, a, of, animals"
39041,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.1,"the, of, that, a, animals"
39042,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.1,"the, that, a, animals"
39043,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.1,"the, is, and, of"
39044,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.1,"the, is, to, covs"
39045,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.1,"animals, from, to, for, the"
39046,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.1,"the, animals, to, infection"
39047,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.1,"a, related, the, to"
39048,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.1,"the, covid-19, to, a"
39049,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.1,"wild, the, which, is"
39050,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.1,"the, covs, to, a, which"
39051,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.1,"to, the, for, wild"
39052,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.1,"a, to, which, the"
39053,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.1,"to, humans,, the, of, from, them"
39054,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.1,"of, a, the, to, covs, and"
39055,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.1,"also, to, and, a, the, of"
39056,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.1,"and, that, from, the, bat, of"
39057,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.1,"from, humans, the, of, that, a, to"
39058,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.1,"the, to, mers-cov, and, that"
39059,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.1,"the, a, from, as, to"
39060,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.1,"has, been, bat, that, and, a"
39061,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.1,"to, that, the, most, of, and"
39062,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.1,"to, that, the, of, and, as, hosts"
39063,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.1,"the, of, that, a, has, been"
39064,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.1,"sequence, with, a, sars-cov-2"
39065,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.1,"that, and, sequence, identity"
39066,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.1,"has, been, a, that, bat, and"
39067,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.1,"bat, cov, with, sars-cov-2, that"
39068,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.1,"bat, might, sars-cov-2, and"
39069,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.1,"the, coronavirus, has, and, identity, with"
39070,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.1,"sars-cov-2, a, and, from, be, to, coronavirus, in"
39071,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.1,"a, coronavirus, in, the, with, to"
39072,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.1,"a, intermediate, sars-cov-2, with, the, in"
39073,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.1,"the, in, sars-cov-2, with, amino, acid, be"
39074,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.1,"the, whether, and, intermediate, from, a, in, with, to"
39075,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.1,"available, and, is"
39076,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.1,"available, bats, the"
39077,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.1,"and, of, species,, many"
39078,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.1,"other, coronaviruses, of, and"
39079,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.1,"of, and, is, an, humans"
39080,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.1,"is, humans, and, of, an"
39081,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","zoonotic corona- 

viruses have become an increasing threat to human health,",0.1,"human, viruses, to"
39082,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","zoonotic corona- 

viruses have become an increasing threat to human health,",0.1,"have, zoonotic, to"
39083,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.1,"zoonotic, and, to"
39084,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.1,"of, a, natural, origin"
39085,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.1,"sars-, cov-2, of, more, origin"
39086,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.1,"of, more, likely, a"
39087,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.1,"that, has, a, origin, or"
39088,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.1,"of, the, have, a, at"
39089,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.1,"also, that, the, of, have, to"
39090,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","ARS-CoV-2 is a 

natural virus, not a lab-created one.",0.1,"natural, not, a"
39091,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.1,"are, the, most, other"
39092,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.1,"with, wildlife, the, most"
39093,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.1,"the, other, not"
39094,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.1,"sars-cov-2, to, a, that, did, not, in, an"
39095,"with the first case being linked to  

a seafood market","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.1,"first, to, a"
39096,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.1,"a, sars-cov-2, from, bat, in"
39097,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.1,"intermediate, host, sars-cov-2"
39098,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.1,"in, a, sars-cov-2, to, that"
39099,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.1,"is, to, that, sars-cov-2, a"
39100,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.1,"a, that, to, sars-cov-2"
39101,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.1,"to, that, sars-cov-2, t"
39102,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.1,"that, sars-cov-2, to, a"
39103,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.1,"is, that, the, humans"
39104,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.1,"sars-cov-2, as, to, that, may, in"
39105,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.1,"such, as, to, that, sars-cov-2, may, in"
39106,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.1,"the, possibility, of, sars-cov-2"
39107,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.1,"that, the, of, not, doesn’t, a, origin."
39108,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.1,"the, has, sars-cov-2"
39109,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.1,"sars-cov-2, a, that"
39110,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.1,"of, a, that, the"
39111,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.1,"the, not, other"
39112,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.1,"it, that, sars-cov-2, laboratory, of, a"
39113,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.1,"that, the, in, and, to, intermediate, of"
39114,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.1,"that, such, as, may, to, sars-cov-2, in"
39115,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.1,"been, suggested, that, sars-cov-2, in, before"
39116,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.1,"have, been, to, sars-cov-2, as, the"
39117,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.1,"was, the"
39118,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.1,"sars-cov-2, the"
39119,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.1,"the, from, was, as, more"
39120,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.1,"an, was, previous, the"
39121,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.1,"the, more, likely, from"
39122,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.1,"the, from, zoonotic, transmission"
39123,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.1,"that, humans, animal, sars-cov-2"
39124,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.1,"before, that, suggested, sars-cov-2, been, in"
39125,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.1,"genome, sars-cov-2, the, bat"
39126,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.1,"be, the, bat"
39127,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.1,"sars-cov-2, found, to, be"
39128,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.1,"the, past, of, and, most"
39129,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.1,"is, and, likely, that, of"
39130,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.1,"human, and, virus, the, of"
39131,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.1,"that, of, is, a, the, past"
39132,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.1,"of, the, is, viral"
39133,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.1,"the, a, of, is, most, likely, that, virus, and"
39134,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.1,"a, natural, origin, and"
39135,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.1,"the, of, that, a, human, and"
39136,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.1,"virus, is, the, of, viral"
39137,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",Genetic evidence suggesting otherwise is yet to be presented.,0.1,"be, to, suggesting"
39138,"This suggests that the BANAL series may be able to directly infect  

humans.",Genetic evidence suggesting otherwise is yet to be presented.,0.1,"be, to"
39139,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.1,"sars-cov-2, is, of, an, the"
39140,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.1,"that, sars-cov-2, natural, is, or"
39141,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.1,"the, of, with, sars-cov-2, these, or"
39142,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.1,"of, these, even, with, sars-cov-2"
39143,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.1,"that, sars-cov-2, the, with, or"
39144,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.1,"the, that, sars-cov-2, laboratory, or, for"
39145,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.1,"is, the, to, in, and"
39146,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.1,"have, their, origin, in, and"
39147,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.1,"and, the, has, to, of"
39148,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.1,"sars-cov-2, of, natural, the, and, to, in"
39149,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.1,"its, the, from, a, in"
39150,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.1,"a, from, the, strain, which"
39151,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.1,"receptor, a, spike, pangolin"
39152,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.1,"the, not, is, by, a"
39153,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.1,"has, to, and"
39154,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.1,"be, and, an"
39155,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.1,"are, from, viruses"
39156,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.1,"and, sars-cov-2, to"
39157,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.1,"that, and, to, from"
39158,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.1,"and, that, sars-cov-2, to"
39159,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.1,"to, sars-cov-2, from, and"
39160,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.1,"was, from, and, to"
39161,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.1,"sars-cov-2, and, was"
39162,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.1,"in, amino, acid, sequences, of"
39163,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.1,"that, in, bats, and, to, of"
39164,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.1,"that, of, sars-cov-2, and, more, bats"
39165,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.1,"these, bat, ratg13, of"
39166,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.1,"of, genome, with, bat"
39167,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.1,"of, with, sars-cov-2, genome"
39168,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.1,"even, these, with, of, sars-cov-2"
39169,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.1,"of, sars-cov-2, than"
39170,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.1,"evidence, that, the"
39171,evidence suggests bats as its origin,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.1,"evidence, as"
39172,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.1,"the, that, has, and, to"
39173,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.1,"the, has, to, that, from, and"
39174,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.1,"but, to, is, the, has, and"
39175,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.1,"and, that, the, has, to"
39176,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.1,"that, the, between, and, is"
39177,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.1,"to, been, by, and, the"
39178,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.1,"that, been, by, to, and, the"
39179,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.1,"coronaviruses, genetic, to"
39180,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.1,"to, sars-cov-2, be, the"
39181,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.1,"of, the, other, with"
39182,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.1,"the, of, natural, to"
39183,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.1,"sars-cov-2, to, the, with"
39184,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.1,"consistent, to, the, of, sars-cov-2"
39185,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.1,"of, sars-cov-2, bat, sars-cov"
39186,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.1,"we, sars-cov-2, of"
39187,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.1,"sars-cov-2, closest, of, and"
39188,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.1,"to, the, emergence, of, which"
39189,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.1,"in, the, of, its"
39190,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.1,"to, in, the, ace2"
39191,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.1,"the, sars-cov-2, in, its"
39192,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.1,"the, of, sars-cov-2, to, ace2"
39193,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.1,"the, of, to, its"
39194,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.1,"the, that, a, in, coronavirus, nature"
39195,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.1,"and, more, that, of, sars-cov-2, to, be, by"
39196,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.1,"the, of, and, that, among, in, genomes, are, to"
39197,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.1,"this, of, and, are, by, suggesting, in, the"
39198,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.1,"by, et, al., complete, in, that, the, to, of"
39199,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.1,"the, and, in, to, suggesting, that, these, are, of"
39200,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.1,"and, of, this, natural, the"
39201,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.1,"evidence, that, the, natural, of, and"
39202,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.1,"the, of, that, most, to, and"
39203,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.1,"evidence, that, the, of, to"
39204,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.1,"research, that, sars-cov-2, the"
39205,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.1,"be, the, genomic, that, bats"
39206,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.1,"coronavirus, and, from, to"
39207,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.1,"the, also, to, from"
39208,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.1,"that, the, genomes, sars-cov-2, and, a"
39209,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.1,"obtained, from, the, bat, and"
39210,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.1,"the, to, sars-cov-2, that, pangolin"
39211,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.1,"that, and, bats"
39212,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.1,"pangolins, provides, and, sars-cov-2"
39213,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.1,"t, that, the, genome"
39214,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.1,"that, are, the, genome"
39215,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.1,"are, the, covid-19, virus, bats"
39216,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.1,"that, the, covid-19, virus"
39217,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.1,"bats, are, virus, the"
39218,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.1,"the, more, than, bats"
39219,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.1,"that, the, covid-19, hosts, for"
39220,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.1,"a, of, the, in, was, is, to"
39221,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.1,"of, the, were, to, that, was"
39222,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.1,"of, in, the, market, wuhan, by"
39223,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.1,"the, of, shows, that, by, a"
39224,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.1,"a, of, in, bats, the, china"
39225,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.1,"in, china, by, et, al., were, found"
39226,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.1,"were, by, bats, in, the"
39227,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.1,"et, al., that, the, complete, to, by, in, of"
39228,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.1,"(2020), a, of, in, is, the, to"
39229,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.1,"of, the, in, that, a, group"
39230,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.1,"bats, to, sars-cov-2, the"
39231,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.1,"a, bats, the, as"
39232,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.1,"is, the, bat, to"
39233,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.1,"the, of, to, sars-like, bat"
39234,"Bats are natural hosts of many of the known  

coronaviruses","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.1,"of, many, the"
39235,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.1,"that, of, to, a, analysis, the"
39236,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.1,"of, and, bat, a, the"
39237,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.1,"a, of, that, sars, the, to, virus"
39238,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.1,"a, which, of, covs."
39239,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.1,"a, virus, bat, to, of, and"
39240,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.1,"covs, a, of, and, the, to"
39241,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.1,"genome, bat, of, origin"
39242,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.1,"sars-cov-2, et, the, of"
39243,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.1,"the, in, sars-cov-2, at, by"
39244,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.1,"shows, in, of, bat"
39245,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.1,"genome, of, to, bat"
39246,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.1,"and, to, of, the, viral, a"
39247,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.1,"the, of, is, to, human, for"
39248,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.1,"a, in, similarity, of, sars-cov-2"
39249,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.1,"sars-cov-2, a, and, in, an"
39250,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.1,"viruses, a, which, is, of"
39251,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.1,"a, (2020), in, the, is, to, of"
39252,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.1,"that, in, with, sars-cov-2"
39253,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.1,"suggests, that, in, for"
39254,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.1,"the, and, are, similar, to"
39255,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.1,"have, the, of, to, a, and"
39256,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.1,"the, that, of, for, sars-cov-2"
39257,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.1,"to, the, that, been, by, and"
39258,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.1,"are, hosts, of, and, a, to, that"
39259,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.1,"the, genomic, than, that, in, and"
39260,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.1,"a, of, the, genomic, novel, coronavirus, that"
39261,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.1,"of, the, spike, protein, in, a"
39262,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.1,"that, the, backbone, of, a, coronavirus"
39263,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.1,"the, to, have, sars-cov-2"
39264,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.1,"have, the, sars-cov-2, to"
39265,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.1,"belonging, to, the"
39266,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.1,"to, have, the"
39267,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.1,"have, the, to"
39268,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.1,"been, the, have"
39269,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.1,"as, to, the, sars-cov-2, have, been"
39270,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.1,"the, two, viruses, in"
39271,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.1,"sequences, and, that, of, in"
39272,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.1,"the, viruses, sars-cov-2, of"
39273,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.1,"the, in, a, of, group, viruses, with, that, and"
39274,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.1,"sars-cov-2, a, and, in"
39275,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.1,"in, with, sars-cov-2, the, of"
39276,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.1,"a, in, that, the, group, of"
39277,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.1,"the, and, a, in, that, of"
39278,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.1,"and, of, that, viruses, in"
39279,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.1,"is, to, than"
39280,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.1,"we, of, sars-cov-2"
39281,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.1,"the, viruses, and, are, members, of, bat"
39282,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.1,"these, viruses, in, to, the"
39283,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.1,"that, to, the, and, for"
39284,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.1,"the, that, are, at, with, for"
39285,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.1,"that, the, bat, ratg13, at"
39286,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.1,"sars-cov-2, is, that, bats, the"
39287,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.1,"the, is, hosts, bat"
39288,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.1,"at, are, this, the, that"
39289,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.1,"sars-cov-2, the, this, that, for, is"
39290,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.1,"with, bat, cov, that, sars-cov-2"
39291,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.1,"bats, of, and, the"
39292,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.1,"and, has, been, of"
39293,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.1,"sars-cov-2, from, bats, the"
39294,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.1,"bats, the, likely, of"
39295,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.1,"sars-cov-2, and, from, that, coronavirus, bats"
39296,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.1,"coronavirus, the, that, of"
39297,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.1,"the, that, novel, this, coronavirus"
39298,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.1,"from, the, more, likely"
39299,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.1,"bats, more, that, of, sars-cov-2, and"
39300,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.1,"in, the, between, and"
39301,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.1,"between, (or, and, the, in"
39302,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.1,"and, in, to, that, the, is, sars-cov-2"
39303,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same",0.1,"the, and, had"
39304,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.1,"the, between, sars-cov-2, and, is, that, bat"
39305,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.1,"this, in, the, that, sars-cov-2, ratg13, pangolin"
39306,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.1,"cov, and, sars-cov-2, all, together, with, than"
39307,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.1,"the, have, in, which"
39308,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.1,"the, to, have, in, with"
39309,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.1,"in, the, sars-cov-2, originated, or"
39310,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.1,"that, the, of, in, to, with, and"
39311,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.1,"of, to, the, those, in, that, they"
39312,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.1,"obtained, in, the, bat, of, and, those"
39313,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.1,"of, the, sars-"
39314,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.1,"this, of, bat, the"
39315,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.1,"the, are, in, bats"
39316,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.1,"the, are, sars-cov-2, when"
39317,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.1,"and, sars-cov-2, than, which"
39318,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.1,"and, that, observed, which, pangolin"
39319,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.1,"s, the, is, than, bat"
39320,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.1,"is, between, and, that, sars-cov-2"
39321,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.1,"the, and, bat, that, s, ratg13"
39322,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.1,"that, bat, similarity, sars-cov-2"
39323,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.1,"and, bat, between, the, same"
39324,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.1,"guangdong, is, sars-cov-2, the, s"
39325,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.1,"that, pangolin, and, the"
39326,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.1,"and, is, that, ratg13, bat"
39327,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.1,"bat, with, sars-cov-2"
39328,"The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.1,"the, that, with"
39329,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.1,"the, that, with, sars-cov-2, or"
39330,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.1,"suggest, that, the, origin, sars-cov-2"
39331,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.1,"the, that, sars-cov-2, has"
39332,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.1,"the, sars-cov-2, origin"
39333,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.1,"that, sars-cov-2, origin"
39334,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.1,"the, of, more, sars-cov-2"
39335,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.1,"the, this, that, of"
39336,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.1,"of, the, sars-cov-2, origin"
39337,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.1,"the, of, sequences, this"
39338,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.1,"the, of, sars-cov-2, this"
39339,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.1,"or, of, and, the, bat"
39340,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.1,"and, origin, of, the"
39341,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.1,"and, of, sars-cov-2, their, the"
39342,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.1,"this, sars-cov-2, or"
39343,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.1,"the, and, that, sars-cov-2, is"
39344,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.1,"the, and, bat, that, ratg13, viruses"
39345,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.1,"have, with, the, and, into, bat"
39346,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.1,"sars-cov-2, have, and, are, the"
39347,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.1,"all, cov, have, origin, and"
39348,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.1,"in, or, bats"
39349,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.1,"have, that, in, bats"
39350,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.1,"or, bats, in"
39351,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.1,"sars-cov-2, this, or"
39352,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.1,"this, that, in"
39353,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.1,"evidence, that, sars-cov-2, origin, and"
39354,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.1,"the, of, pangolins, and, more, sars-cov-2"
39355,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.1,"the, as, of, that, to, hosts, and"
39356,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.1,"origin, of, sars-, cov-2, more"
39357,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.1,"the, of, sars-cov-2, to, consistent"
39358,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.1,"suggest, that, sars-cov-2, the, origin"
39359,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.1,"the, origin, and, in"
39360,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.1,"origin, of, the, from, early, and, in"
39361,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.1,"the, in, from, of, bat"
39362,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.1,"in, the, early, and, these, obtained"
39363,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.1,"the, obtained, from, bat, and"
39364,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.1,"in, the, obtained, those, and, of, bat"
39365,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.1,"virus, between, the, and"
39366,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.1,"the, of, a, genome, and"
39367,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.1,"to, the, sars-cov-2, also, and"
39368,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.1,"the, are, to, a, of, on, that, and, other"
39369,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.1,"sars-cov-2, a, origin, and"
39370,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.1,"a, to, of, and, are, on"
39371,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.1,"similar, sars-cov-2, the, of, on"
39372,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.1,"a, of, also, and, the, to"
39373,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.1,"to, and, of, that, similar"
39374,Bats are likely reservoir hosts for SARS-CoV-2,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.1,"are, likely, sars-cov-2"
39375,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.1,"a, to, the, of, with, pangolin"
39376,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.1,"a, of, more, likely"
39377,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.1,"that, to, with, and"
39378,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.1,"with, that, sars-cov-2, and, similarity"
39379,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.1,"sars-cov-2, that, with, to"
39380,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.1,"pangolin-cov, to, sars-cov-2, that"
39381,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.1,"and, sars-cov-2, to, the, with"
39382,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.1,"of, the, to, with"
39383,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.1,"to, is, sars-cov-2, the"
39384,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.1,"and, to, the, of, is, sars-cov-2"
39385,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.1,"with, the, of, sars-cov-2, and"
39386,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.1,"sars-cov-2, and, the"
39387,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.1,"and, the, is, same"
39388,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.1,"sars-cov-2, is, with, the"
39389,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.1,"is, sars-cov-2, and, the"
39390,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.1,"with, the, of, sars-cov-2"
39391,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.1,"the, of, by, highest"
39392,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.1,"of, sars-cov-2, by, the"
39393,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.1,"and, the, for"
39394,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.1,"for, the, and"
39395,"identified numerous human–animal interactions that con- 

stitute emergence risk factors, for example bat tourism, wet 

markets, wildlife supply chains for human consumption,15 land 

management practices, and environmental perturbations.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.1,"that, emergence, for, and"
39396,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.1,"the, of, that, in"
39397,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.1,"between, and, the, in"
39398,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.1,"the, evidence, that"
39399,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.1,"in, the, and, that, sars-cov-2, of"
39400,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.1,"and, in, that, the, of, sars-cov-2"
39401,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.1,"the, and, from, palm, civet"
39402,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.1,"cov, in, and, from"
39403,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.1,"the, from, civet, palm"
39404,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.1,"of, and, that, bats, for"
39405,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.1,"have, the, of, and, sars-cov"
39406,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.1,"are, including, previous"
39407,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.1,"and, all, sars-cov-2, together, with, cov, than"
39408,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.1,"sars-cov-2, and, the, with, for"
39409,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.1,"and, for, sars-cov-2, the, with"
39410,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.1,"similarity, is, sars-cov-2, the"
39411,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.1,"the, and, sars-cov-2, to"
39412,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.1,"the, and, in, are, to"
39413,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.1,"and, are, in, the"
39414,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.1,"sars-cov-2, and, in"
39415,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.1,"are, in, to"
39416,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.1,"in, sars-cov-2, the, binding"
39417,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.1,"in, and, the"
39418,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.1,"the, and, in, to, are"
39419,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.1,"that, the, of, this"
39420,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.1,"that, the, and, in"
39421,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.1,"and, of, in, the, for"
39422,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.1,"that, suggests, for, in"
39423,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.1,"that, the, and, pangolin"
39424,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.1,"sars-cov-2, of, has, to, virus, that, and, the"
39425,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.1,"of, the, virus, with, and"
39426,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.1,"of, sars-cov-2, and, closest"
39427,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.1,"the, that, bat, and"
39428,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.1,"that, in, can, and"
39429,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.1,"the, an, in, and"
39430,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.1,"the, be, in"
39431,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.1,"can, be, of, and, in"
39432,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.1,"the, be, bat"
39433,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.1,"that, recombination, of, and, the"
39434,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.1,"that, from, to, humans."
39435,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.1,"identity, sars-cov-2, the, of, from"
39436,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.1,"of, sars-cov-2, to, suggesting, that"
39437,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.1,"of, the, that, sars-cov-2, at, in, which"
39438,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.1,"the, pangolin, to, sars-cov-2"
39439,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.1,"that, sars-cov-2, to, the, in, rbd"
39440,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.1,"the, that, sars-cov-2, to, pangolin"
39441,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.1,"that, sars-cov-2, to, pangolin-cov"
39442,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.1,"sars-cov-2, virus, the, cov"
39443,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.1,"in, to, that, the, of, is, sars-cov-2"
39444,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.1,"sars-cov-2, intermediate, host"
39445,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.1,"the, of, that, sars-cov-2, to, events."
39446,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.1,"the, of, to, rbd, virus"
39447,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.1,"the, of, virus, from, a, with, to"
39448,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.1,"the, then, zoonotic, of, from, a, by"
39449,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.1,"from, a, to, the, bind"
39450,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.1,"zoonotic, transmission, from, the"
39451,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.1,"the, those, in, that"
39452,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.1,"for, the, first"
39453,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.1,"the, origin, as"
39454,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.1,"in, that, the, first"
39455,evidence suggests bats as its origin,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.1,"as, origin"
39456,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.1,"be, to, that, sars-cov-2"
39457,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.1,"that, from, is"
39458,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.1,"that, sars-cov-2, to, is"
39459,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.1,"sars-cov-2, is, to, that"
39460,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.1,"to, be, likely"
39461,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.1,"from, is, to, that"
39462,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.1,"unknown, of, animal"
39463,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.1,"the, an, of, and"
39464,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.1,"study, the, of, bat, and"
39465,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.1,"an, intermediate, animal"
39466,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.1,"bat, and, sars-cov-2, might"
39467,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.1,"the, of, and, be"
39468,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.1,"sars-cov-2, the, host, bat"
39469,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.1,"the, and, an, of"
39470,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.1,"cov, the, another, sars-cov-2, and"
39471,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.1,"and, the, virus"
39472,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.1,"an, and, be"
39473,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.1,"the, virus, between, and"
39474,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.1,"the, sars-cov-2, cov, virus"
39475,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.1,"the, sars-cov-2, a, of, is, in"
39476,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.1,"that, of, sars-cov-2, the, for"
39477,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.1,"evidence, that, circulating, the, of"
39478,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.1,"in, a, but, animal"
39479,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.1,"in, the, a, that, from, for"
39480,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.1,"from, in, the, that, a, sars-cov-2"
39481,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.1,"the, that, in, a, from"
39482,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.1,"the, that, in, animal"
39483,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.1,"in, the, a, from, that, for"
39484,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.1,"animal, a, in, the, that"
39485,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.1,"the, that, sars-cov-2, or, laboratory, for"
39486,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.1,"sars-cov-2, originated, in, the, or"
39487,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.1,"to, the, with, is"
39488,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.1,"natural, and, is, not"
39489,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.1,"and, to, the, natural, of, with"
39490,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.1,"with, the, of, to, an"
39491,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.1,"sars-cov-2, of, coronaviruses, from, including"
39492,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.1,"of, sars-cov-2, including, relatives"
39493,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.1,"from, a, in, china"
39494,"According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.1,"sars-cov-2, close, of"
39495,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.1,"of, in, from, a"
39496,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.1,"sars-cov-2, from, a, of, in, coronaviruses"
39497,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.1,"the, are, also"
39498,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.1,"are, also, a, for, the, and"
39499,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.1,"and, a, origin, the"
39500,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.1,"and, also, a, the, for"
39501,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.1,"with, sars-cov-2, zoonotic, events"
39502,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.1,"a, coronavirus, that, with, to"
39503,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.1,"to, of, may, be, a"
39504,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.1,"a, that, with, sars-cov-2, in"
39505,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.1,"that, sars-cov-2, with, of, to"
39506,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.1,"of, to, suggesting, that, sars-cov-2"
39507,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.1,"sars-cov-2, be, of, zoonotic, with, to, in"
39508,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.1,"a, to, that, in, human, and"
39509,"bats are also important reservoir species for a great 

range of coronaviruses","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.1,"bats, are, important, a, of"
39510,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.1,"to, that, are, related, in, and"
39511,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.1,"of, to, that, bats, as, hosts"
39512,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.1,"that, a, of, to, and, are, hosts"
39513,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.1,"the, at, was, in"
39514,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.1,"the, has, which, with"
39515,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.1,"the, of, can, to, that, animal"
39516,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.1,"of, the, that, similar, to"
39517,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.1,"in, the, of, that, to, similar"
39518,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.1,"such, the, of, to, can, that, natural"
39519,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.1,"the, of, natural, in, a, similar, to, that"
39520,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.1,"similar, to, the, in, of, that, a"
39521,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.1,"coronavirus, and, in, the, of, from, hosts"
39522,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.1,"coronavirus, is, and, very, from, to"
39523,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.1,"that, the, of, were, in, to, and"
39524,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.1,"is, that, sars-cov-2, the, and, from"
39525,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.1,"to, sars-cov-2, were, and, in, the"
39526,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.1,"closely, related, to, sars-cov-2,, and, the, is"
39527,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.1,"in, is, that, the, be, and, sars-cov-2"
39528,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.1,"sars-cov-2, is, natural, that, found, to, the"
39529,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.1,"is, sars-cov-2, and, to, the, that, in"
39530,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.1,"in, the, of, is, to, sars-cov-2, that"
39531,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.1,"in, to, of, than"
39532,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.1,"of, to, is, coronavirus, in, the"
39533,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.1,"of, the, sequence, is"
39534,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.1,"is, the, to, bat"
39535,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.1,"in, ace2, of, to, and, the"
39536,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.1,"that, are, the, to, suggesting, these, in, of, and"
39537,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.1,"viruses, to, bat, that, of"
39538,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.1,"and, that, is, of, bat"
39539,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.1,"that, is, in, bat"
39540,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.1,"and, in, is, similar, to, ratg13"
39541,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.1,"it, in, related, and, similar, to"
39542,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.1,"it, is, possible, that, of"
39543,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.1,"in, of, similar, to, that"
39544,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.1,"of, that, to, bat, and"
39545,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.1,"of, in, and, that, viruses"
39546,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.1,"that, and, bat, ratg13, is"
39547,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.1,"that, similar, to, and, of"
39548,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.1,"sars-cov-2, from, pangolins, of, found"
39549,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.1,"evidence, the, that, as, to"
39550,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.1,"study, the, of, with"
39551,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.1,"the, an, to, that, of"
39552,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.1,"pangolin, to, the, that, protein, of"
39553,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.1,"of, the, also, that, have, to"
39554,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.1,"to, that, the, of, evidence"
39555,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.1,"the, of, evidence, that, circulating"
39556,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.1,"the, an, with, to, of"
39557,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.1,"amino, acid, the, to"
39558,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.1,"sars-cov-2, genetic, with, many, and, virus"
39559,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.1,"sars-cov-2, and, with, the, of, virus, in"
39560,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.1,"analysis, of, the, sars-cov-2, with, and"
39561,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.1,"recent, the, of, to, high, and, viruses"
39562,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.1,"and, in, to, the, of, sars-cov-2, natural"
39563,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.1,"in, of, sars-cov-2, to, be, with, zoonotic"
39564,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.1,"sars-cov-2, and, high, to, the, of"
39565,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.1,"the, to, similarity, and"
39566,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.1,"identity, the, sars-cov-2, bat"
39567,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.1,"sars-cov-2, of, the, and, high, to"
39568,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.1,"a, the, is"
39569,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.1,"the, is, sars-cov-2, that"
39570,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.099337748,"in, a, of, to, sars-related, coronaviruses, the, from, bats, for, and, had, sars, genome, were"
39571,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.099337748,"to, the, sars, bats, were, for, and, a, in, of, from, had, sars-related, coronaviruses, genome"
39572,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.09929078,"the, and, of, a, or, that, were, in, this, animal, palm, infected, at, market"
39573,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.09929078,"this, that, palm, were, infected, in, the, market, a, or, at, and, of, animal"
39574,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.099236641,"a, of, the, in, an, to, with, study, found, that, from, intermediate, host"
39575,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.099236641,"study, that, of, from, to, an, intermediate, host, a, found, in, with, the"
39576,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.099236641,"a, study, by, from, at, market, in, that, the, to, of, were, found"
39577,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.099236641,"a, of, the, market, at, were, by, in, to, study, found, that, from"
39578,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.099173554,"at, some, had, to, as, in, for, the, virus, of, and, other"
39579,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.099173554,"and, in, were, found, to, related, indicating, that, the, of, coronavirus, sars-cov-2"
39580,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.099173554,"a, of, the, market, at, and, by, to, with, taken, from, 18"
39581,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.099173554,"the, by, taken, from, a, at, market, and, to, of, 18, with"
39582,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.099173554,"as, in, the, of, and, at, to, for, other, some, virus, had"
39583,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.099173554,"sars-cov-2, and, of, the, to, related, in, were, found, that, coronavirus, indicating"
39584,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.099099099,"an, to, a, as, in, for, the, virus, of, and, also"
39585,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.099099099,"the, for, of, all, to, that, no, infected, other, at, market"
39586,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.099099099,"the, as, for, and, a, reservoir, of, study, high, sequence, identity"
39587,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.099099099,"the, were, for, a, in, of, from, sequence, analysis, that, isolated"
39588,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.099099099,"sars-cov-2, may, in, of, animal, and, cats, that, the, with, for"
39589,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.099099099,"sars-cov-2, and, of, the, cats, animal, in, with, that, for, may"
39590,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.099099099,"the, a, of, researchers, with, available, evidence,, that, were, by, and"
39591,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.099099099,"a, study, for, the, as, reservoir, of, high, and, sequence, identity"
39592,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.099099099,"analysis, sequence, in, the, of, a, isolated, from, that, were, for"
39593,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.099099099,"the, as, a, species, of, that, bats,, to, civets, by, and"
39594,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.099099099,"also, a, for, as, the, of, virus, and, in, to, an"
39595,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.099099099,"available, evidence,, by, a, of, researchers, the, that, were, and, with"
39596,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.099099099,"to, for, the, of, no, infected, at, market, all, other, that"
39597,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.099099099,"by, the, of, a, species, bats,, to, that, civets, as, and"
39598,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.099009901,"a, for, the, out, as, natural, of, is, it, human"
39599,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.099009901,"the, that, of, natural, genetic, is, it, as, an, for"
39600,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.099009901,"it, human, as, the, out, a, of, is, for, natural"
39601,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.099009901,"infected, a, as, in, the, or, china, live, were, of"
39602,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.099009901,"the, and, also, a, in, to, that, bat, are, of"
39603,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.099009901,"less, the, two, at, to, a, is, closely, related, and"
39604,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.099009901,"and, with, wuhan, the, huanan, seafood, of, team, collected, a"
39605,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.099009901,"two, less, closely, related, to, and, a, at, the, is"
39606,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.099009901,"is, a, virus, that, found, infected, wildlife, to, the, for"
39607,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.099009901,"a, known, zoonotic, and, in, the, that, to, 2002-2003, sars"
39608,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.099009901,"the, first, was, to, this, would, that, in, with, of"
39609,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.099009901,"the, infected, in, china, live, were, or, as, a, of"
39610,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.099009901,"the, is, that, of, are, with, market, and, in, one"
39611,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.099009901,"collected, a, team, of, the, wuhan, and, with, huanan, seafood"
39612,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.099009901,"to, the, 2002-2003, sars, zoonotic, known, and, a, in, that"
39613,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.099009901,"the, are, in, of, one, with, is, that, and, market"
39614,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.099009901,"the, found, that, for, virus, to, wildlife, infected, a, is"
39615,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.099009901,"the, was, first, to, that, with, this, would, in, of"
39616,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.099009901,"that, it, as, the, an, of, genetic, is, for, natural"
39617,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.099009901,"and, the, of, bat, also, to, are, a, that, in"
39618,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.098901099,"the, that, was, to, in, is, genome., bats,, and"
39619,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.098901099,"genetic, evidence, the, that, a, as, it, to, humans"
39620,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.098901099,"the, is, that, to, a, of, it, has, been"
39621,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.098901099,"is, the, to, that, in, bats,, and, was, genome."
39622,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.098901099,"market,, the, with, at, on, cases, were, confirmed, by"
39623,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.098901099,"that, it, to, as, the, humans, a, genetic, evidence"
39624,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.098901099,"in, the, that, of, positive, were, to, from, market"
39625,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.098901099,"of, a, to, that, in, respiratory, syndrome, middle, east"
39626,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.098901099,"and, the, infected, to, a, bats, that, in, virus"
39627,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.098901099,"the, cases, on, with, were, at, market,, confirmed, by"
39628,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.098901099,"the, first, animals, from, for, virus, to, a, is"
39629,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.098901099,"that, it, to, the, a, of, is, has, been"
39630,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.098901099,"the, in, a, for, of, on, was, that, and"
39631,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.098901099,"and, the, of, as, a, bats, with, for, its"
39632,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.098901099,"in, the, live, animal, at, to, species, were, and"
39633,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.098901099,"the, and, to, were, in, sars-cov-2, live, animal, at"
39634,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.098901099,"that, the, virus, in, bats, and, to, infected, a"
39635,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.098901099,"with, the, of, bats, as, a, for, its, and"
39636,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.098901099,"the, to, of, as, group, is, most, virus, by"
39637,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.098901099,"a, virus, from, animals, to, for, the, first, is"
39638,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.098901099,"animal, species, to, were, live, and, in, at, the"
39639,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.098901099,"the, was, in, and, on, that, for, a, of"
39640,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.098901099,"the, group, of, most, virus, to, as, by, is"
39641,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.098901099,"that, the, virus, in, bats, and, to, china,, of"
39642,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.098901099,"animal, to, sars-cov-2, were, live, and, in, at, the"
39643,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.098901099,"in, the, and, that, of, environmental, samples, huanan, from"
39644,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.098901099,"in, of, to, the, that, from, were, market, positive"
39645,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.098901099,"and, environmental, samples, the, huanan, that, of, in, from"
39646,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.098901099,"the, to, in, of, china,, that, bats, virus, and"
39647,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.098901099,"or, bats, the, can, bats., of, and, in, may"
39648,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.098901099,"can, or, of, bats., and, the, in, bats, may"
39649,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.098901099,"that, of, in, to, middle, east, respiratory, syndrome, a"
39650,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.098765432,"in, an, ace2, of, to, sars-cov-2, and, the"
39651,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.098765432,"the, in, of, an, to, that, sars-cov-2, virus"
39652,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.098765432,"and, human, that, a, origin, of, the, virus"
39653,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.098765432,"of, a, that, the, virus, to, which, and"
39654,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.098765432,"that, sars-cov-2, to, and, a, the, origin, of"
39655,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.098765432,"in, the, and, to, sars-cov-2, is, of, bat"
39656,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.098765432,"and, the, of, bat, to, with, that, is"
39657,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.098765432,"the, a, of, that, from, humans, by, and"
39658,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.098765432,"in, a, of, the, from, live, market, positive"
39659,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.098765432,"in, a, of, to, have, the, that, from"
39660,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.098765432,"in, the, market, live, positive, from, a, of"
39661,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.098765432,"from, in, the, of, that, a, have, to"
39662,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.098765432,"a, for, the, as, positive, of, wild, is"
39663,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.098765432,"to, in, the, this, that, for, is, of"
39664,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.098765432,"a, of, the, are, that, have, to, virus"
39665,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.098765432,"to, that, the, of, have, as, for, are"
39666,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.098765432,"on, in, the, of, a, that, were, most"
39667,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.098765432,"cases, and, the, of, in, this, al., published"
39668,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.098765432,"a, of, the, is, wild, for, as, positive"
39669,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.098765432,"the, of, on, is, for, natural, reservoir, a"
39670,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.098765432,"the, of, as, was, at, found, to, and"
39671,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.098765432,"with, the, and, to, of, pangolin, sars-, as"
39672,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.098765432,"and, from, to, the, seafood, market, in, a"
39673,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.098765432,"a, the, of, in, on, that, were, most"
39674,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.098765432,"the, of, on, for, likely, in, a, that"
39675,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.098765432,"the, likely, that, for, of, in, from, a"
39676,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.098765432,"in, viruses, are, and, bat, ratg13, that, the"
39677,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.098765432,"the, of, as, a, at, that, both, and"
39678,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.098765432,"for, and, the, in, of, on, a, was"
39679,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.098765432,"in, 2, sars-cov-2, with, pangolin, that, the, is"
39680,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.098765432,"sars-cov-2, of, to, ace2, in, an, and, the"
39681,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.098765432,"bats, the, several, species, of, to, and, in"
39682,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.098765432,"the, of, with, that, and, is, to, bat"
39683,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.098765432,"the, viruses, are, also, closely, related, to, of"
39684,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.098765432,"the, of, and, are, similar, to, is, that"
39685,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.098765432,"the, a, which, to, in, and, at, was"
39686,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.098765432,"the, of, also, to, viruses, are, closely, related"
39687,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.098765432,"and, the, of, to, similar, are, that, is"
39688,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.098765432,"a, for, the, on, natural, reservoir, of, is"
39689,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.098765432,"on, in, the, of, a, that, likely, for"
39690,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.098765432,"to, in, the, that, for, is, of, natural"
39691,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.098765432,"a, of, the, wiv, by, that, to, virus"
39692,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.098765432,"the, and, a, suggesting, that, these, of, sars-cov-2,"
39693,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.098765432,"evidence, to, that, the, of, and, as, for"
39694,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.098765432,"as, the, was, found, to, at, of, and"
39695,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.098765432,"that, the, of, and, at, both, as, a"
39696,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.098765432,"the, from, a, seafood, market, in, to, and"
39697,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.098765432,"the, was, in, and, on, for, a, of"
39698,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.098765432,"that, the, covid-19, in, and, to, wuhan, of"
39699,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.098765432,"al., the, of, cases, and, published, in, this"
39700,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.098765432,"in, the, of, a, from, that, likely, for"
39701,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.098765432,"in, of, to, the, that, this, is, for"
39702,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.098765432,"the, of, is, for, natural, in, to, that"
39703,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.098765432,"to, this, for, the, of, that, sars-cov-2, in"
39704,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.098765432,"sars-cov-2, of, to, virus, that, in, an, the"
39705,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.098765432,"the, wuhan, that, in, of, to, and, covid-19"
39706,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.098765432,"and, in, that, the, of, bats, are, natural"
39707,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.098765432,"in, species, of, bats, to, and, the, several"
39708,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.098765432,"other, are, also, to, and, on, the, of"
39709,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.098765432,"was, in, a, and, which, to, at, the"
39710,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.098765432,"a, of, the, from, by, that, and, humans"
39711,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.098765432,"the, by, and, to, that, of, bat, as"
39712,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.098765432,"a, of, to, have, the, are, virus, that"
39713,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.098765432,"the, of, by, wiv, a, virus, to, that"
39714,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.098765432,"to, by, the, of, that, have, been, a"
39715,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.098765432,"to, sars-cov-2, in, the, this, that, for, of"
39716,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.098765432,"a, of, the, been, by, that, have, to"
39717,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.098765432,"origin, of, human, a, virus, that, and, the"
39718,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.098765432,"of, which, to, a, virus, that, and, the"
39719,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.098765432,"of, natural, on, the, and, in, binding, protein"
39720,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.098765432,"the, and, bat, that, in, ratg13, viruses, are"
39721,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.098765432,"that, is, in, pangolin, with, sars-cov-2, the, 2"
39722,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.098765432,"and, sars-, to, the, of, with, pangolin, as"
39723,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.098765432,"the, as, of, that, to, by, bat, and"
39724,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.098765432,"of, to, have, the, are, that, for, as"
39725,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.098765432,"for, the, of, and, that, evidence, as, to"
39726,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.098765432,"sars-cov-2, origin, of, to, a, that, and, the"
39727,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.098765432,"on, the, of, are, to, and, other, also"
39728,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.098765432,"that, bats, are, the, natural, of, and, in"
39729,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.098765432,"a, of, the, sars-cov-2,, that, and, these, suggesting"
39730,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.098765432,"on, the, of, in, binding, protein, and, natural"
39731,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.098684211,"from, the, for, to, a, sars-related, that, as, and, sars, in, of, isolated, known, an"
39732,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.098684211,"to, the, sars, as, for, known, and, a, in, of, from, that, sars-related, an, isolated"
39733,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.098591549,"bats, of, and, a, large, that, in"
39734,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.098591549,"the, sars-cov-2, to, with, in, of, and"
39735,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.098591549,"the, of, as, host, and, more, than"
39736,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.098591549,"the, in, a, as, to, of, and"
39737,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.098591549,"a, and, with, the, of, virus, in"
39738,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.098591549,"and, in, their, to, the, of, is"
39739,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.098591549,"is, to, the, that, an, and, be"
39740,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.098591549,"and, bat, coronaviruses, a, in, are, to"
39741,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.098591549,"a, from, bat, to, and, are, as"
39742,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.098591549,"of, have, the, that, was, from, being"
39743,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.098591549,"at, the, institute, of, and, that, not"
39744,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.098591549,"and, at, the, that, was, of, from"
39745,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.098591549,"the, that, sars-cov-2, were, at, by, before"
39746,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.098591549,"at, this, the, sars-cov-2, we, that, are"
39747,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.098591549,"this, that, sars-cov-2, the, origin, of, we"
39748,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.098591549,"a, in, the, that, sars-cov-2, from, pandemic"
39749,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.098591549,"sars-cov-2, of, in, the, and, that, with"
39750,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.098591549,"that, the, market, in, to, we, a"
39751,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.098591549,"a, as, the, of, and, in, to"
39752,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.098591549,"sars-cov-2, a, from, to, that, may, in"
39753,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.098591549,"sars-cov-2, is, and, from, to, that, in"
39754,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.098591549,"to, the, for, viruses, in, and, of"
39755,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.098591549,"the, by, that, sars-cov-2, at, were, before"
39756,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.098591549,"the, it, that, spillover, in, from, a"
39757,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.098591549,"that, have, from, the, was, being, of"
39758,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.098591549,"the, covid-19, market, is, of, a, to"
39759,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.098591549,"the, that, same, virus, found, in, were"
39760,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.098591549,"is, to, have, likely, in, the, same"
39761,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.098591549,"the, of, that, are, likely, to, a"
39762,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.098591549,"and, that, not, the, at, institute, of"
39763,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.098591549,"that, the, most, plausible, of, and, is"
39764,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.098591549,"the, is, and, it, not, what, of"
39765,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.098591549,"in, a, we, that, the, to, market"
39766,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.098591549,"of, was, to, the, emergence, in, animals"
39767,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.098591549,"in, the, of, that, virus, to, than"
39768,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.098591549,"such, as, and, the, of, to, et"
39769,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.098591549,"of, to, the, virus, that, is, from"
39770,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.098591549,"the, of, and, that, virus, from, to"
39771,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.098591549,"that, the, sars-cov-2, to, by, of, and"
39772,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.098591549,"to, of, in, bats, the, and, has"
39773,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.098591549,"be, natural, on, the, and, to, sars-"
39774,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.098591549,"is, a, sequence, and, bat, as, high"
39775,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.098591549,"as, and, the, of, it, is, natural"
39776,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.098591549,"the, of, and, sars-cov, at, which, as"
39777,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.098591549,"from, bat, to, of, and, more, as"
39778,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.098591549,"the, and, zc45, to, that, bat, of"
39779,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.098591549,"a, the, of, virus, and, in, with"
39780,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.098591549,"the, coronavirus, in, of, that, these, a"
39781,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.098591549,"to, a, are, and, coronaviruses, in, bat"
39782,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.098591549,"the, that, of, are, and, sequences, in"
39783,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.098591549,"the, a, sequence, that, sequences, in, coronaviruses"
39784,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.098591549,"from, in, that, a, sars-cov-2, may, to"
39785,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.098591549,"that, sars-cov-2, to, from, and, is, in"
39786,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.098591549,"a, as, bat, is, high, and, sequence"
39787,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.098591549,"to, that, bats, and, may, as, sars-cov-2"
39788,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.098591549,"as, the, at, which, sars-cov, of, and"
39789,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.098591549,"the, of, is, a, virus, to, that"
39790,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.098591549,"the, of, with, and, huanan, at, in"
39791,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.098591549,"in, the, of, and, to, viruses, for"
39792,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.098591549,"of, and, a, to, that, in, human"
39793,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.098591549,"that, the, of, species, in, a, to"
39794,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.098591549,"the, is, that, of, with, sequences, in"
39795,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.098591549,"the, is, coronavirus, a, that, sequences, in"
39796,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.098591549,"from, and, sars-cov-2, has, to, in, the"
39797,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.098591549,"such, as, et, the, of, and, to"
39798,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.098591549,"the, as, natural, of, is, and, it"
39799,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.098591549,"to, that, the, of, and, as, sars-cov-2"
39800,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.098591549,"that, the, and, in, between, pangolins, for"
39801,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.098591549,"and, to, be, the, of, is, sars-cov-2"
39802,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.098591549,"in, to, of, the, has, bats, and"
39803,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.098591549,"to, with, of, and, in, cave, bats"
39804,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.098591549,"by, a, of, the, between, and, suggesting"
39805,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.098591549,"that, of, to, a, in, species, the"
39806,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.098591549,"but, can, a, bat, to, of, as"
39807,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.098591549,"a, in, that, the, closely, to, of"
39808,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.098591549,"are, and, a, which, related, to, in"
39809,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.098591549,"the, natural, reservoir, is, search, to, of"
39810,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.098591549,"the, a, at, to, and, closely, related"
39811,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.098591549,"of, by, the, to, virus, closely, related"
39812,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.098591549,"in, the, when, that, infected, humans, and"
39813,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.098591549,"of, and, by, suggesting, a, between, the"
39814,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.098591549,"the, of, closely, related, virus, to, by"
39815,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.098591549,"in, by, closely, related, the, palm, civet"
39816,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.098591549,"that, the, with, of, virus, less, to"
39817,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.098591549,"the, virus, to, that, of, and, from"
39818,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.098591549,"the, earliest, and, of, evidence, a, to"
39819,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.098591549,"the, that, virus, found, in, with, were"
39820,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.098591549,"to, likely, in, the, host, with, or"
39821,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.098591549,"the, of, that, likely, to, a, with"
39822,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.098591549,"the, as, of, and, host, more, than"
39823,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.098591549,"of, to, the, than, in, that, virus"
39824,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.098591549,"closely, related, to, and, a, at, the"
39825,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.098591549,"in, humans, that, the, and, when, infected"
39826,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.098591549,"a, of, to, the, covid-19, is, market"
39827,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.098591549,"the, of, and, a, earliest, evidence, to"
39828,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.098591549,"and, to, this, the, that, in, a"
39829,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.098591549,"the, of, and, that, sequences, in, are"
39830,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.098591549,"that, of, is, in, with, sequences, the"
39831,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.098591549,"the, that, in, a, it, spillover, from"
39832,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.098591549,"of, the, spike, in, a, to, that"
39833,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.098591549,"in, the, of, a, coronavirus, that, these"
39834,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.098591549,"to, that, the, of, bats, and, have"
39835,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.098591549,"that, and, for, pangolins, the, between, in"
39836,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.098591549,"in, the, virus, that, were, found, same"
39837,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.098591549,"the, were, that, virus, found, in, with"
39838,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.098591549,"to, of, in, bats, cave, and, with"
39839,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.098591549,"in, palm, civet, by, the, closely, related"
39840,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.098591549,"from, to, a, are, as, and, bat"
39841,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.098591549,"of, from, to, bat, as, and, more"
39842,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.098591549,"of, bat, as, but, can, a, to"
39843,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.098591549,"of, a, the, virus, to, which, and"
39844,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.098591549,"and, from, in, the, of, is, sars-cov-2"
39845,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.098591549,"the, reservoir, and, it, not, to, of"
39846,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.098591549,"the, of, is, and, in, their, to"
39847,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.098591549,"the, is, and, be, that, to, an"
39848,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.098591549,"the, of, in, emergence, was, to, animals"
39849,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.098591549,"the, coronaviruses, that, sequences, a, sequence, in"
39850,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.098591549,"that, is, a, coronavirus, in, sequences, the"
39851,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.098591549,"the, also, has, a, in, that, coronaviruses"
39852,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.098591549,"in, this, be, that, the, and, of"
39853,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.098591549,"the, of, and, that, is, most, plausible"
39854,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.098591549,"that, the, of, in, closely, a, to"
39855,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.098591549,"of, at, the, in, a, to, that"
39856,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.098591549,"the, of, a, which, to, and, virus"
39857,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.098591549,"the, by, of, and, (2020), that, a"
39858,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.098591549,"(2020), that, by, a, of, and, the"
39859,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.098591549,"the, we, this, that, sars-cov-2, are, at"
39860,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.098591549,"that, the, is, bats, are, hosts, sars-cov-2"
39861,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.098591549,"and, is, that, viruses, ratg13, in, bat"
39862,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.098591549,"in, to, have, the, likely, is, same"
39863,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.098591549,"the, host, in, likely, or, with, to"
39864,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.098591549,"that, with, the, of, pangolin, to, as"
39865,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.098591549,"sars-cov-2, and, as, to, that, may, bats"
39866,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.098591549,"as, and, the, of, to, that, sars-cov-2"
39867,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.098591549,"to, the, have, bats, of, and, that"
39868,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.098591549,"a, of, to, the, are, likely, that"
39869,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.098591549,"the, of, that, a, likely, with, to"
39870,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.098591549,"that, the, be, in, this, of, and"
39871,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.098591549,"origin, of, the, we, this, that, sars-cov-2"
39872,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.098591549,"a, the, pandemic, from, that, sars-cov-2, in"
39873,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.098591549,"the, of, and, it, not, is, what"
39874,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.098591549,"the, of, is, search, natural, reservoir, to"
39875,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.098591549,"reservoir, and, it, to, not, the, of"
39876,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.098591549,"a, large, of, and, that, in, bats"
39877,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.098591549,"in, of, to, that, human, and, a"
39878,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.098591549,"in, a, related, and, which, are, to"
39879,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.098591549,"the, of, that, spike, in, a, to"
39880,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.098591549,"a, at, in, that, the, to, of"
39881,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.098591549,"the, of, sars-cov-2, to, be, is, and"
39882,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.098591549,"of, the, sars-cov-2, in, from, is, and"
39883,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.098591549,"is, the, sars-cov-2, that, bats, are, hosts"
39884,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.098591549,"the, of, that, to, bat, zc45, and"
39885,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.098591549,"the, also, has, a, that, in, coronaviruses"
39886,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.098591549,"in, viruses, and, bat, ratg13, that, is"
39887,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.098591549,"with, the, to, that, of, pangolin, as"
39888,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.098591549,"to, on, the, sars-, and, natural, be"
39889,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.098484848,"infected, bat, to, a, as, in, for, the, virus, of, and, other, also"
39890,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.098484848,"and, the, of, infected, bat, also, to, as, a, other, in, for, virus"
39891,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.098360656,"the, in, a, of, virus,, and"
39892,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.098360656,"a, and, the, of, from, in"
39893,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.098360656,"sars-cov, such, and, to, have, in"
39894,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.098360656,"the, in, a, as, to, of"
39895,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.098360656,"a, sars-cov-2, with, the, of, in"
39896,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.098360656,"sars-cov-2, the, in, that, any, is"
39897,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.098360656,"coronaviruses, are, to, that, of, and"
39898,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.098360656,"that, was, the, sars-cov-2, and, to"
39899,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.098360656,"of, that, such, as, and, more"
39900,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.098360656,"that, many, of, and, sequences, in"
39901,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.098360656,"that, sars-cov-2, including, its, and, to"
39902,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.098360656,"the, including, animal, and, of, sars-cov-2"
39903,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.098360656,"to, sars-cov-2, the, including, that, of"
39904,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.098360656,"of, the, that, have, to, origin"
39905,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.098360656,"that, is, in, a, an, to"
39906,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.098360656,"the, to, coronavirus, and, that, a"
39907,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.098360656,"of, also, to, ace2, the, in"
39908,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.098360656,"to, a, in, the, and, that"
39909,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.098360656,"bats, hosts, of, to, humans,, as"
39910,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.098360656,"the, of, that, likely, to, infected"
39911,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.098360656,"in, and, were, linked, to, market"
39912,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.098360656,"the, and, to, sars-cov-2, is, of"
39913,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.098360656,"the, been, bats, of, and, that"
39914,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.098360656,"the, virus, for, to, that, and"
39915,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.098360656,"a, origin, the, from, sars-cov-2, zoonotic"
39916,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.098360656,"from, to, the, coronavirus, is, sars-cov-2"
39917,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.098360656,"and, identity, with, sars-cov-2, to, the"
39918,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.098360656,"the, of, for, natural, sars, that"
39919,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.098360656,"the, that, a, novel, in, coronavirus"
39920,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.098360656,"evidence, bats, the, of, in, pangolins"
39921,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.098360656,"its, to, that, and, including, sars-cov-2"
39922,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.098360656,"sars-cov-2, could, the, and, has, that"
39923,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.098360656,"the, genomic, and, that, through, natural"
39924,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.098360656,"the, a, from, sars-cov-2, zoonotic, origin"
39925,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.098360656,"that, sars-cov-2, a, origin, and, virus."
39926,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.098360656,"of, the, viruses, a, at, their"
39927,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.098360656,"the, of, that, potential, support, hypothesis"
39928,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.098360656,"are, a, the, in, that, to"
39929,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.098360656,"in, to, of, sars-cov-2, on, and"
39930,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.098360656,"a, of, and, the, virus,, in"
39931,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.098360656,"as, a, of, the, in, to"
39932,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.098360656,"the, in, as, a, source, of"
39933,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.098360656,"the, of, and, animal, including, sars-cov-2"
39934,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.098360656,"in, the, of, indicated, sars-cov-2, but"
39935,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.098360656,"a, that, the, sars-cov-2, also, to"
39936,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.098360656,"have, the, sars-cov-2, of, to, that"
39937,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.098360656,"in, two, lineages, of, have, to"
39938,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.098360656,"the, viruses, to, are, more, in, of, make, and, if, would, at"
39939,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.098360656,"in, the, of, and, at, are, if, to, make, viruses, would, more"
39940,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.098360656,"that, the, of, in, was, to, or, not, she, said,, have, by"
39941,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.098360656,"that, be, sars-cov-2, on, the, with"
39942,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.098360656,"a, from, as, to, that, in"
39943,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.098360656,"to, the, in, that, animals, a"
39944,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.098360656,"the, team, a, from, as, to"
39945,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.098360656,"the, of, a, in, scientists, to, that, as, were, find, virus, for"
39946,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.098360656,"this, that, are, the, likely, of"
39947,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.098360656,"the, virus, is, and, that, in"
39948,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.098360656,"a, is, in, that, to, an"
39949,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.098360656,"evidence, that, the, of, to, an"
39950,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.098360656,"the, that, was, to, have, in, by, of, or, she, said,, not"
39951,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.098360656,"on, the, and, that, coronavirus, a"
39952,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.098360656,"of, origin,, and, zoonotic, to, infection"
39953,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.098360656,"in, the, of, host, was, and"
39954,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.098360656,"a, coronavirus, the, and, that, to"
39955,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.098360656,"the, of, in, study, a, published"
39956,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.098360656,"confirmed, the, and, of, et, to"
39957,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.098360656,"in, et, al., of, and, to"
39958,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.098360656,"and, the, of, to, that, is"
39959,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.098360656,"horseshoe, which, to, that, of, and"
39960,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.098360656,"to, the, bats, and, that, a"
39961,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.098360656,"a, which, the, bat, from, pangolin"
39962,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.098360656,"to, the, genome, and, that, for"
39963,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.098360656,"the, of, and, intermediate, human, to"
39964,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.098360656,"the, is, that, of, and, sequences"
39965,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.098360656,"a, to, and, the, market, in"
39966,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.098360656,"that, the, in, a, to, genetic"
39967,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.098360656,"the, that, market, and, in, at"
39968,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.098360656,"at, the, in, a, to, that"
39969,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.098360656,"the, of, which, but, was, to"
39970,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.098360656,"and, to, of, which, in, the"
39971,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.098360656,"the, that, is, part, of, as"
39972,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.098360656,"natural, the, and, to, in, virus"
39973,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.098360656,"in, to, the, virus, that, is"
39974,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.098360656,"the, and, in, virus, that, is"
39975,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.098360656,"the, and, that, virus, in, to"
39976,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.098360656,"the, and, to, that, is, of"
39977,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.098360656,"the, to, is, natural, on, or"
39978,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.098360656,"may, to, and, the, intermediate, for"
39979,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.098360656,"the, and, of, sequence, is, bat"
39980,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.098360656,"that, the, is, related, to, bats"
39981,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.098360656,"the, in, a, as, source, of"
39982,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.098360656,"a, with, the, of, in, china"
39983,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.098360656,"of, that, the, bat, a, possible"
39984,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.098360656,"also, the, that, a, sars-cov-2, to"
39985,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.098360656,"a, the, also, by, that, to"
39986,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.098360656,"to, that, the, and, for, sars-cov-2"
39987,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.098360656,"of, the, similar, to, can, animal"
39988,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.098360656,"the, rbd, of, to, at, which"
39989,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.098360656,"in, intermediate, humans, to, human, and"
39990,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.098360656,"the, of, that, sars-cov-2, have, to"
39991,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.098360656,"et, the, of, and, confirmed, to"
39992,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.098360656,"the, of, bat, is, and, sequence"
39993,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.098360656,"of, the, that, have, to, virus"
39994,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.098360656,"the, that, of, genetic, sars-cov-2, is"
39995,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.098360656,"a, origin, virus., that, sars-cov-2, and"
39996,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.098360656,"the, that, from, infected, humans, and"
39997,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.098360656,"and, to, that, the, of, coronavirus"
39998,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.098360656,"in, the, of, virus, with, and"
39999,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.098360656,"in, with, and, the, whole, genome"
40000,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.098360656,"from, to, be, the, of, bats"
40001,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.098360656,"in, of, for, with, human, and"
40002,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.098360656,"are, coronaviruses, common, in, with, and"
40003,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.098360656,"and, of, in, which, for, human"
40004,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.098360656,"the, reservoirs, or, of, bats, and"
40005,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.098360656,"the, to, a, and, pangolin, coronavirus"
40006,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.098360656,"and, that, of, more, such, as"
40007,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.098360656,"the, of, as, genome, from, and"
40008,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.098360656,"to, and, of, that, related, bat"
40009,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.098360656,"to, of, the, and, has, that"
40010,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.098360656,"that, from, a, sars-cov-2, analysis, the"
40011,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.098360656,"not, a, and, the, from, through"
40012,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.098360656,"a, and, the, to, from, animals"
40013,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.098360656,"a, of, and, the, from, in"
40014,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.098360656,"the, with, in, china, a, of"
40015,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.098360656,"a, the, of, and, with, that"
40016,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.098360656,"that, in, a, as, to, from"
40017,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.098360656,"coronaviruses, from, and, which, in, sars-cov-2"
40018,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.098360656,"sars-cov-2, is, to, in, bat, which"
40019,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.098360656,"indicates, that, sars-cov-2, is, a, in"
40020,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.098360656,"two, and, a, at, the, which"
40021,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.098360656,"the, of, sars-cov-2, at, that, which"
40022,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.098360656,"the, of, potential, support, hypothesis, that"
40023,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.098360656,"but, to, of, the, which, was"
40024,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.098360656,"the, of, to, that, this, evidence"
40025,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.098360656,"on, in, the, to, huanan, market"
40026,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.098360656,"the, a, of, from, to, bat"
40027,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.098360656,"the, of, and, that, a, in"
40028,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.098360656,"that, of, a, in, pangolin, the"
40029,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.098360656,"the, of, that, in, a, and"
40030,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.098360656,"a, was, in, that, the, of"
40031,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.098360656,"the, of, as, a, from, and"
40032,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.098360656,"in, the, but, indicated, of, sars-cov-2"
40033,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.098360656,"a, and, which, to, the, level"
40034,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.098360656,"the, genome, of, from, as, and"
40035,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.098360656,"of, the, virus, in, with, and"
40036,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.098360656,"of, human, and, for, in, with"
40037,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.098360656,"the, analysis, that, sars-cov-2, from, a"
40038,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.098360656,"the, pangolin, in, that, a, of"
40039,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.098360656,"sars-cov-2, and, coronaviruses, from, which, in"
40040,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.098360656,"and, sars-cov-2, that, the, same, is"
40041,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.098360656,"in, the, to, sars-cov-2, of, ratg13"
40042,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.098360656,"in, found, to, the, of, sars-cov-2"
40043,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.098360656,"bats, of, and, several, to, in"
40044,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.098360656,"by, and, in, to, the, is"
40045,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.098360656,"the, with, sars-cov-2, that, hosts, for"
40046,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.098360656,"the, on, that, be, with, sars-cov-2"
40047,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.098360656,"be, in, the, that, sars-cov-2, for"
40048,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.098360656,"sars-cov-2, be, the, to, ace2, rbd"
40049,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.098360656,"a, team, to, the, from, as"
40050,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.098360656,"from, intermediate, as, to, the, a"
40051,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.098360656,"in, the, at, were, to, and"
40052,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.098360656,"that, sars-cov-2, has, could, and, the"
40053,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.098360656,"and, that, the, has, to, of"
40054,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.098360656,"to, of, from, a, with, sars-cov-2"
40055,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.098360656,"the, of, to, it, that, bats"
40056,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.098360656,"genome, of, the, covid-19, virus, from"
40057,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.098360656,"to, the, in, of, a, covid-19"
40058,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.098360656,"and, the, bats, reservoirs, of, or"
40059,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.098360656,"the, species, of, most, likely, and"
40060,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.098360656,"bat, to, bats, of, and, as"
40061,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.098360656,"the, of, are, and, within, in"
40062,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.098360656,"genetic, that, the, in, to, a"
40063,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.098360656,"to, of, that, viruses, in, bat"
40064,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.098360656,"to, sars-cov-2, from, a, of, with"
40065,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.098360656,"whole, genome, the, in, with, and"
40066,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.098360656,"the, to, a, level, and, which"
40067,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.098360656,"by, and, in, to, the, sars-cov-2"
40068,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.098360656,"of, the, sars, that, natural, for"
40069,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.098360656,"a, of, the, at, viruses, their"
40070,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.098360656,"the, and, at, two, which, a"
40071,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.098360656,"in, the, virus, to, closely, related"
40072,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.098360656,"are, coronaviruses, and, common, in, with"
40073,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.098360656,"sars-cov-2, the, and, in, related, coronaviruses"
40074,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.098360656,"bat, and, the, are, sars-cov-2, with"
40075,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.098360656,"in, the, of, was, host, and"
40076,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.098360656,"human, to, in, humans, and, intermediate"
40077,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.098360656,"that, the, and, infected, humans, from"
40078,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.098360656,"to, were, and, in, at, the"
40079,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.098360656,"in, a, of, scientists, to, the, find, virus, that, were, for, as"
40080,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.098360656,"and, the, to, a, market, in"
40081,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.098360656,"and, the, of, to, is, natural"
40082,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.098360656,"sequences, and, that, of, in, many"
40083,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.098360656,"the, of, and, sequences, that, is"
40084,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.098360656,"within, of, and, are, in, the"
40085,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.098360656,"a, study, published, in, the, of"
40086,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.098360656,"were, linked, to, and, market, in"
40087,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.098360656,"to, the, huanan, market, in, on"
40088,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.098360656,"sars-cov-2, a, in, the, that, with"
40089,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.098360656,"to, on, the, natural, is, or"
40090,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.098360656,"to, on, the, evidence, that, or"
40091,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.098360656,"to, of, bats, the, it, that"
40092,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.098360656,"in, the, a, that, from, to"
40093,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.098360656,"the, of, to, that, including, sars-cov-2"
40094,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.098360656,"natural, of, and, a, which, that"
40095,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.098360656,"related, coronaviruses, in, sars-cov-2, the, and"
40096,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.098360656,"and, of, sars-cov-2, in, is, the"
40097,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.098360656,"to, or, through, contact, and, in"
40098,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.098360656,"in, the, a, novel, coronavirus, that"
40099,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.098360656,"a, of, the, possible, bat, that"
40100,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.098360656,"the, of, that, as, intermediate, evidence"
40101,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.098360656,"is, a, the, bat, receptor, from"
40102,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.098360656,"the, of, and, that, in, to"
40103,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.098360656,"the, of, that, in, and, to"
40104,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.098360656,"the, and, in, to, that, of"
40105,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.098360656,"been, that, bats, and, the, of"
40106,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.098360656,"the, that, in, a, to, animals"
40107,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.098360656,"the, to, that, of, and, coronavirus"
40108,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.098360656,"to, a, that, bats, and, the"
40109,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.098360656,"the, covid-19, of, to, a, in"
40110,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.098360656,"the, of, that, a, been, in"
40111,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.098360656,"the, bats, pangolins, evidence, in, of"
40112,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.098360656,"bats, of, a, diversity, in, as"
40113,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.098360656,"and, to, through, in, contact, or"
40114,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.098360656,"to, in, and, bats, or, be"
40115,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.098360656,"bats, to, as, of, bat, and"
40116,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.098360656,"pangolins, be, although, they, are, with"
40117,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.098360656,"are, also, to, and, a, on"
40118,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.098360656,"the, is, of, with, in, at"
40119,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.098360656,"of, amino, at, the, in, similar"
40120,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.098360656,"a, of, the, this, that, and"
40121,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.098360656,"the, through, and, not, from, a"
40122,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.098360656,"the, from, a, animals, to, and"
40123,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.098360656,"the, species, to, reservoir, of, and"
40124,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.098360656,"to, the, of, from, zoonotic, a"
40125,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.098360656,"the, of, infected, that, to, likely"
40126,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.098360656,"the, to, from, of, a, bat"
40127,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.098360656,"the, most, likely, species, of, and"
40128,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.098360656,"of, to, a, from, rhinolophus, bat"
40129,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.098360656,"the, sars-cov-2, identity, with, and, to"
40130,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.098360656,"the, origin, of, to, that, have"
40131,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.098360656,"a, that, the, also, to, by"
40132,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.098360656,"have, the, of, virus, to, that"
40133,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.098360656,"in, such, have, to, sars-cov, and"
40134,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.098360656,"natural, of, and, a, that, human"
40135,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.098360656,"the, genetic, sars-cov-2, of, is, that"
40136,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.098360656,"the, and, in, is, to, by"
40137,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.098360656,"in, by, and, to, sars-cov-2, the"
40138,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.098360656,"the, a, which, from, pangolin, bat"
40139,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.098360656,"the, is, bat, a, receptor, from"
40140,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.098360656,"and, are, of, coronaviruses, that, to"
40141,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.098360656,"of, sars-cov-2, in, and, to, on"
40142,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.098360656,"which, to, that, of, and, horseshoe"
40143,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.098360656,"to, be, the, of, natural, sars-cov-2"
40144,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.098360656,"also, the, of, in, to, ace2"
40145,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.098360656,"to, the, of, and, that, emergence"
40146,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.098360656,"sars-cov-2, be, based, on, the, recent"
40147,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.098360656,"the, sars-cov-2, and, to, a, bat"
40148,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.098360656,"and, a, to, the, coronavirus, pangolin"
40149,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.098360656,"that, is, related, to, bats, the"
40150,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.098360656,"(2020), that, the, of, from, bats"
40151,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.098360656,"are, sars-cov-2, bat, that, the, is"
40152,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.098360656,"of, a, in, sars-cov-2, sequences, the"
40153,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.098360656,"a, of, from, to, bat, rhinolophus"
40154,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.098360656,"of, human, and, which, for, in"
40155,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.098360656,"in, a, of, for, sars-cov-2, to"
40156,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.098360656,"in, two, of, lineages, have, to"
40157,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.098360656,"et, al., of, and, in, to"
40158,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.098360656,"although, they, with, are, pangolins, be"
40159,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.098360656,"to, the, and, may, intermediate, for"
40160,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.098360656,"genomic, that, through, natural, and, the"
40161,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.098360656,"on, the, a, coronavirus, that, and"
40162,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.098360656,"the, for, genome, to, that, and"
40163,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.098360656,"are, in, to, the, bats, and"
40164,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.098360656,"the, to, on, or, that, evidence"
40165,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.098360656,"to, or, be, and, in, bats"
40166,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.098360656,"sars-cov-2, that, the, with, hosts, for"
40167,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.098360656,"(2020), from, that, the, of, bats"
40168,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.098360656,"is, that, are, the, sars-cov-2, bat"
40169,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.098360656,"sars-cov-2, is, bat, to, which, in"
40170,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.098360656,"is, that, the, as, part, of"
40171,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.098360656,"the, of, ratg13, to, sars-cov-2, in"
40172,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.098360656,"of, the, are, likely, that, this"
40173,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.098360656,"the, likely, that, of, sars-cov-2, this"
40174,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.098360656,"are, with, sars-cov-2, the, bat, and"
40175,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.098360656,"that, the, sars-cov-2, and, for, to"
40176,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.098360656,"on, and, also, are, to, a"
40177,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.098360656,"are, of, and, a, to, that"
40178,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.098360656,"in, and, pangolin, this, that, the"
40179,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.098360656,"the, to, at, which, rbd, of"
40180,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.098360656,"that, the, of, sars-cov-2, at, which"
40181,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.098360656,"a, of, zoonotic, the, to, from"
40182,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.098360656,"the, rbd, a, to, bind, of"
40183,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.098360656,"sars-cov-2, is, a, indicates, that, in"
40184,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.098360656,"the, been, in, of, that, a"
40185,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.098360656,"that, be, for, sars-cov-2, the, in"
40186,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.098360656,"a, of, sars-cov-2, in, for, to"
40187,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.098360656,"to, humans,, of, bats, as, hosts"
40188,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.098360656,"in, of, bats, to, and, several"
40189,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.098360656,"and, of, which, that, a, natural"
40190,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.098360656,"a, diversity, of, in, bats, as"
40191,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.098360656,"and, human, that, a, natural, of"
40192,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.098360656,"that, are, to, and, a, of"
40193,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.098360656,"the, of, similar, to, animal, can"
40194,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.098360656,"in, similar, at, the, amino, of"
40195,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.098360656,"to, the, coronavirus, from, sars-cov-2, is"
40196,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.098360656,"to, the, of, rbd, a, bind"
40197,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.098360656,"of, that, to, bat, and, related"
40198,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.098360656,"that, of, bat, in, viruses, to"
40199,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.098360656,"that, the, of, evidence, to, an"
40200,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.098360656,"zoonotic, origin,, of, to, and, infection"
40201,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.098360656,"the, natural, to, virus, in, and"
40202,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.098360656,"the, rbd, be, to, sars-cov-2, ace2"
40203,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.098360656,"recent, be, the, sars-cov-2, based, on"
40204,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.098214286,"the, and, of, a, to, in, is, between, sars-cov-2, be, other"
40205,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.098214286,"the, that, to, are, coronavirus, in, is, of, can, and, into"
40206,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.098214286,"are, coronavirus, the, of, is, can, and, in, that, to, into"
40207,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.098214286,"in, a, of, to, coronaviruses, the, among, bat, and, genome, viruses"
40208,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.098214286,"of, the, market, in, samples, for, that, from, positive, racoon, dogs"
40209,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.098214286,"evidence, that, the, of, and, two, in, least, for, wildlife, markets"
40210,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.098214286,"positive, samples, from, the, market, that, of, racoon, dogs, in, for"
40211,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.098214286,"viruses, similar, to, the, in, bats, of, and, that, a, china"
40212,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.098214286,"the, genome, of, and, bat, coronaviruses, a, among, in, viruses, to"
40213,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.098214286,"the, between, sars-cov-2, and, to, be, a, of, is, in, other"
40214,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.098214286,"the, of, a, viruses, in, to, that, bats, and, similar, china"
40215,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.098214286,"in, the, markets, of, that, for, two, least, wildlife, and, evidence"
40216,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.098039216,"the, that, a, of, from"
40217,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.098039216,"that, in, from, a, naturally"
40218,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.098039216,"from, the, that, of, in"
40219,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.098039216,"genetic, sars-cov-2, and, to, bat"
40220,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.098039216,"a, to, in, which, human"
40221,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.098039216,"the, humans, from, of, this"
40222,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.098039216,"the, from, viruses,, as, sars"
40223,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.098039216,"and, coronaviruses, bat, to, in"
40224,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.098039216,"similar, to, have, in, and"
40225,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.098039216,"coronaviruses, in, to, and, sequences"
40226,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.098039216,"infected, coro-, navirus, were, of"
40227,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.098039216,"genome, in, virus, is, to"
40228,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.098039216,"have, to, with, bat, the"
40229,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.098039216,"have, of, to, and, infection"
40230,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.098039216,"a, of, the, sars-cov-2, with"
40231,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.098039216,"a, of, about, that, coronavirus"
40232,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.098039216,"the, sequences, to, that, of"
40233,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.098039216,"to, been, any, the, sars-cov-2"
40234,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.098039216,"that, sars-cov-2, from, to, it"
40235,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.098039216,"a, the, to, have, sars-cov-2"
40236,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.098039216,"the, of, human, coronaviruses, bat"
40237,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.098039216,"the, sars-cov-2, is, in, sequence"
40238,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.098039216,"the, that, sequence, was, a"
40239,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.098039216,"from, the, that, in, sars-cov-2"
40240,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.098039216,"the, other, and, a, laboratory"
40241,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.098039216,"is, that, sars-cov-2, a, virus"
40242,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.098039216,"a, with, other, and, sars-cov-2"
40243,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.098039216,"a, other, with, sars-cov-2, and"
40244,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.098039216,"and, a, sars-cov-2, their, is"
40245,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.098039216,"to, have, with, the, bat"
40246,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.098039216,"the, sars-cov-2, to, natural, that"
40247,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.098039216,"a, of, the, bat, that"
40248,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.098039216,"is, a, the, bat, ratg13,"
40249,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.098039216,"of, has, been, origin, virus"
40250,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.098039216,"and, a, the, natural, of"
40251,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.098039216,"that, the, was, and, to"
40252,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.098039216,"that, species,, such, as, in"
40253,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.098039216,"phylogenetic, analysis, that, of, and"
40254,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.098039216,"transmission, or, with, of, and"
40255,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.098039216,"is, sars-cov-2, the, sequence, in"
40256,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.098039216,"the, and, in, is, to"
40257,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.098039216,"is, sars-cov-2, the, of, genome"
40258,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.098039216,"animal, and, the, that, to"
40259,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.098039216,"the, of, that, sars-cov-2, animal"
40260,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.098039216,"of, the, than, they, been"
40261,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.098039216,"is, and, to, human, in"
40262,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.098039216,"the, spillover, as, to, of"
40263,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.098039216,"of, the, in, had, been"
40264,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.098039216,"the, of, to, it, is"
40265,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.098039216,"of, the, in, origin, is"
40266,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.098039216,"covid-19, in, the, that, animal"
40267,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.098039216,"in, market, animal, and, a"
40268,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.098039216,"from, species, to, and, the"
40269,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.098039216,"and, can, the, that, natural"
40270,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.098039216,"the, to, that, can, virus"
40271,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.098039216,"and, that, natural, the, virus"
40272,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.098039216,"in, the, which, was, to"
40273,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",Bats are likely reservoir hosts for SARS-CoV-2,0.098039216,"bats, are, likely, hosts, sars-cov-2"
40274,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.098039216,"a, the, sars-cov-2, is, to"
40275,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.098039216,"the, and, to, in, other"
40276,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.098039216,"that, the, of, bat, to"
40277,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.098039216,"the, bats, of, that, outbreak"
40278,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.098039216,"the, novel, coronavirus, and, with"
40279,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.098039216,"a, for, with, the, in"
40280,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.098039216,"from, of, this, the, humans"
40281,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.098039216,"the, of, from, pangolins, sars-cov-2"
40282,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.098039216,"this, is, the, sars-cov-2, bats"
40283,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.098039216,"be, in, the, sars-cov-2, from"
40284,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.098039216,"found, evidence, the, of, to"
40285,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.098039216,"the, a, that, by, and"
40286,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.098039216,"a, of, that, the, from"
40287,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.098039216,"that, sars-cov-2, from, a, the"
40288,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.098039216,"that, the, as, a, of"
40289,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.098039216,"a, of, sars-cov-2, the, to"
40290,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.098039216,"the, genomic, that, only, could"
40291,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.098039216,"the, of, that, was, ratg13"
40292,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.098039216,"the, of, to, a, viruses"
40293,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.098039216,"to, the, that, from, this"
40294,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.098039216,"of, the, from, intermediate, for"
40295,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.098039216,"of, the, intermediate, for, sars-cov-2"
40296,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.098039216,"that, the, in, market, a"
40297,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.098039216,"at, the, and, in, is"
40298,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.098039216,"is, a, the, of, at"
40299,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.098039216,"a, in, with, the, and"
40300,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.098039216,"the, virus, a, of, from"
40301,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.098039216,"been, the, in, of, and"
40302,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.098039216,"from, in, the, of, and"
40303,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.098039216,"of, to, humans, and, sars-cov-2"
40304,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.098039216,"in, two, of, and, to"
40305,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.098039216,"the, in, of, very, to"
40306,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.098039216,"a, along, with, other, sars-cov-2"
40307,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.098039216,"a, and, animal, market, in"
40308,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.098039216,"and, an, in, the, of"
40309,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.098039216,"the, live, animals, in, a, of, presence, animal, and, market"
40310,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.098039216,"to, the, of, sars-, may"
40311,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.098039216,"the, animals, to, in, a, spread, of, one, that, multiple"
40312,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.098039216,"in, was, to, that, sars-cov-2"
40313,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.098039216,"that, is, a, in, sars-cov-2"
40314,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.098039216,"are, closely, related, to, in, more, sars-cov-2, than, the, and"
40315,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.098039216,"the, earliest, cases, were, with"
40316,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.098039216,"as, by, sars-cov-2, at, the"
40317,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.098039216,"a, it, that, the, to"
40318,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.098039216,"the, genetic, genome, to, that"
40319,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.098039216,"the, that, a, in, evidence"
40320,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.098039216,"a, that, from, in, naturally"
40321,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.098039216,"is, that, from, a, in"
40322,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.098039216,"in, is, to, that, a"
40323,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.098039216,"is, that, a, covid-19, from"
40324,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.098039216,"a, in, is, an, to"
40325,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.098039216,"we, a, of, was, likely"
40326,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.098039216,"infected, animals, the, market, have"
40327,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.098039216,"the, that, as, was, to"
40328,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.098039216,"to, on, the, and, that"
40329,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.098039216,"the, that, from, animals, and"
40330,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.098039216,"to, have, of, and, infection"
40331,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.098039216,"that, was, a, the, sequence"
40332,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.098039216,"the, to, that, and, a"
40333,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.098039216,"that, a, the, covid-19, genome"
40334,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.098039216,"a, to, the, bat, and"
40335,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.098039216,"the, in, bats, of, a"
40336,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.098039216,"and, of, the, to, in, were, with, high, that, near"
40337,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.098039216,"in, the, of, to, that"
40338,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.098039216,"the, they, been, of, than"
40339,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.098039216,"been, the, in, of, had"
40340,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.098039216,"this, to, the, that, in"
40341,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.098039216,"in, the, of, virus, those"
40342,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.098039216,"the, such, as, in, and"
40343,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.098039216,"et, and, to, the, of"
40344,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.098039216,"that, about, a, of, coronavirus"
40345,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.098039216,"of, the, from, a, pangolin"
40346,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.098039216,"the, sars-cov-2, have, to, a"
40347,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.098039216,"humans, and, of, sars-cov-2, to"
40348,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.098039216,"with, the, of, from, and"
40349,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.098039216,"to, the, sars-cov-2, from, and"
40350,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.098039216,"a, of, the, to, sars-cov-2"
40351,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.098039216,"suggested, that, the, a, of"
40352,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.098039216,"studies, that, to, sars-cov-2, humans"
40353,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.098039216,"of, sars-cov-2, by, sequences, the"
40354,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.098039216,"bats, and, humans, in, the"
40355,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.098039216,"that, the, and, from, bats"
40356,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.098039216,"the, of, to, most, that"
40357,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.098039216,"that, may, of, to, the"
40358,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.098039216,"bats, are, the, of, which"
40359,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.098039216,"which, was, in, has, the"
40360,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.098039216,"to, in, has, been, that"
40361,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.098039216,"a, of, that, the, as"
40362,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.098039216,"the, to, likely, natural, that"
40363,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.098039216,"is, and, to, that, in"
40364,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.098039216,"and, the, to, that, is"
40365,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.098039216,"and, in, initial, the, of"
40366,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.098039216,"may, of, and, that, the"
40367,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.098039216,"the, and, to, that, may"
40368,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.098039216,"the, for, civet, palm, be"
40369,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.098039216,"the, or, to, and, may"
40370,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.098039216,"a, for, it, with, the"
40371,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.098039216,"the, of, identity, with, sars-cov"
40372,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.098039216,"have, the, infected, animals, market"
40373,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.098039216,"the, and, in, but, also"
40374,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.098039216,"the, is, to, bat, be"
40375,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.098039216,"is, that, sars-cov-2, to, be"
40376,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.098039216,"coro-, navirus, were, of, infected"
40377,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.098039216,"in, a, that, the, market"
40378,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.098039216,"a, of, suggested, that, the"
40379,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.098039216,"a, of, the, with, that"
40380,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.098039216,"have, in, of, as, or"
40381,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.098039216,"of, was, the, in, animals"
40382,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.098039216,"have, that, the, a, of"
40383,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.098039216,"in, it, that, the, of"
40384,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.098039216,"the, palm, civet, be, for"
40385,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.098039216,"genomic, that, could, only, the"
40386,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.098039216,"that, the, novel, of, bat"
40387,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.098039216,"that, the, genomic, bat, only"
40388,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.098039216,"the, of, bat, that, bats"
40389,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.098039216,"bat, the, of, sars-cov-2, 80%"
40390,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.098039216,"the, that, a, it, to"
40391,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.098039216,"the, is, and, it, to"
40392,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.098039216,"similar, to, can, the, of"
40393,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.098039216,"of, to, the, for, coronavirus, bat, genome, more, than, previously"
40394,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.098039216,"for, recombination, and, the, of"
40395,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.098039216,"the, of, sars-cov-2, 80%, bat"
40396,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.098039216,"that, sars-cov-2, the, and, another"
40397,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.098039216,"the, of, sars-cov-2, as, and"
40398,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.098039216,"the, with, and, similarity, sars-cov-2"
40399,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.098039216,"the, of, bat, human, coronaviruses"
40400,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.098039216,"and, sars-cov-2, to, bat, genetic"
40401,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.098039216,"genetic, the, that, genome, to"
40402,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.098039216,"the, of, and, sars-cov-2, genome"
40403,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.098039216,"the, a, of, from, pangolin"
40404,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.098039216,"the, of, spike, protein, a"
40405,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.098039216,"of, the, a, from, as"
40406,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.098039216,"a, of, pangolin, are, the"
40407,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.098039216,"have, by, and, of, is"
40408,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.098039216,"a, to, zoonotic, that, human"
40409,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.098039216,"from, humans, the, sars-cov-2, to"
40410,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.098039216,"coronaviruses, to, sars-cov-2, the, all"
40411,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.098039216,"to, the, bats, are, sars-cov-2"
40412,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.098039216,"the, have, been, to, from"
40413,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.098039216,"to, the, and, or, may"
40414,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.098039216,"that, the, another, sars-cov-2, and"
40415,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.098039216,"to, humans, and, of, sars-cov-2"
40416,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.098039216,"by, that, sars-cov-2, through, and"
40417,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.098039216,"the, of, sequence, was, virus"
40418,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.098039216,"and, was, in, by, the"
40419,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.098039216,"the, of, by, virus, with"
40420,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.098039216,"the, of, in, from, 2020"
40421,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.098039216,"of, analysis, the, virus, and"
40422,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.098039216,"such, as, the, and, in"
40423,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.098039216,"are, that, to, and, viruses"
40424,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.098039216,"to, that, the, and, are"
40425,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.098039216,"the, coronavirus, to, human, a"
40426,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.098039216,"the, sars, viruses,, as, from"
40427,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.098039216,"of, the, sequence, that, and"
40428,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.098039216,"of, the, novel, bat, that"
40429,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.098039216,"laboratory, and, the, other, a"
40430,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.098039216,"and, that, sars-cov-2, through, by"
40431,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.098039216,"et, the, sars-cov-2, from, and"
40432,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.098039216,"the, genomic, bat, that, only"
40433,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.098039216,"the, virus, covid-19, of, and"
40434,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.098039216,"of, the, covid-19, existence, possible"
40435,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.098039216,"and, of, which, is, the"
40436,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.098039216,"in, a, patients, were, that"
40437,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.098039216,"the, of, that, to, sequences"
40438,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.098039216,"a, the, and, in, sars-cov-2"
40439,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.098039216,"the, in, of, sars-cov-2, virus"
40440,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.098039216,"and, a, of, the, virus"
40441,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.098039216,"the, between, sars-cov-2, and, bat"
40442,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.098039216,"the, bat, sequence, in, of"
40443,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.098039216,"in, that, of, the, protein"
40444,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.098039216,"a, of, the, with, sars-cov-2"
40445,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.098039216,"that, the, with, a, of"
40446,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.098039216,"a, with, sars-cov-2, the, and"
40447,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.098039216,"and, a, of, sars-cov-2, the"
40448,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.098039216,"are, hosts, of, infectious, and"
40449,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.098039216,"sars-, the, of, may, to"
40450,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.098039216,"the, results, from, that, sars-cov-2"
40451,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.098039216,"that, is, in, to, sars-cov-2"
40452,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.098039216,"bat, coronavirus, to, sars-cov-2, in"
40453,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.098039216,"the, of, sars-cov-2, and, sars-cov"
40454,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.098039216,"the, was, as, that, to"
40455,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.098039216,"no, that, the, of, to"
40456,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.098039216,"to, in, the, that, of"
40457,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.098039216,"that, of, host, a, the"
40458,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.098039216,"the, a, that, these, of"
40459,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.098039216,"of, to, be, suggesting, that"
40460,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.098039216,"that, the, of, sars-cov-2, analysis"
40461,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.098039216,"lineage, the, of, sars-cov-2, to"
40462,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.098039216,"et, the, of, and, to"
40463,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.098039216,"the, was, to, bat, sars-cov-2"
40464,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.098039216,"to, the, a, in, of, from, horseshoe, (rhinolophus, an, isolated"
40465,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.098039216,"the, was, to, in, of"
40466,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.098039216,"a, in, the, sars-cov-2, from"
40467,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.098039216,"rhinolophus, bats, viruses, have, in"
40468,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.098039216,"the, of, a, for, and"
40469,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.098039216,"in, have, or, as, of"
40470,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.098039216,"the, of, as, sars-cov-2, and"
40471,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.098039216,"that, the, ratg13, was, of"
40472,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.098039216,"of, the, sequence, virus, was"
40473,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.098039216,"the, was, to, virus, that, similar, this, in, of, its"
40474,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.098039216,"a, to, the, coronavirus, human"
40475,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.098039216,"and, the, of, which, a"
40476,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.098039216,"and, human, a, of, the"
40477,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.098039216,"also, found, that, suggesting, to"
40478,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.098039216,"in, and, to, sars-cov-2, the"
40479,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.098039216,"of, and, the, in, viruses"
40480,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.098039216,"from, and, with, the, of"
40481,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.098039216,"the, and, for, a, of"
40482,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.098039216,"the, bats, as, of, and"
40483,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.098039216,"a, of, the, from, bats, for, two, and, genome, were"
40484,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.098039216,"the, of, and, from, bats"
40485,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.098039216,"the, of, from, a, with"
40486,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.098039216,"in, the, a, with, for"
40487,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.098039216,"a, for, the, it, with"
40488,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.098039216,"similarity, sars-cov-2, in, the, for"
40489,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.098039216,"that, the, of, were, in, to, with, high, near, and"
40490,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.098039216,"we, sars-cov-2, and, bat, pangolin, to, the, between, that, in"
40491,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.098039216,"the, of, may, as, to"
40492,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.098039216,"the, of, that, no, to"
40493,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.098039216,"viruses, to, the, that, or"
40494,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.098039216,"sars-cov-2, the, any, been, to"
40495,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.098039216,"sars-cov-2, is, to, that, in"
40496,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.098039216,"in, the, and, a, host,"
40497,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.098039216,"that, sars-cov-2, in, species, humans"
40498,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.098039216,"the, sars-cov-2, and, of, genome"
40499,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.098039216,"in, the, of, which, sars-cov-2"
40500,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.098039216,"the, in, sars-cov-2, with, coronaviruses"
40501,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.098039216,"from, rhinolophus, in, the, which"
40502,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.098039216,"that, of, bat, in, a"
40503,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.098039216,"the, sequence, of, that, and"
40504,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.098039216,"has, found, in, the, to"
40505,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.098039216,"the, et, sars-cov-2, and, from"
40506,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.098039216,"the, from, in, to, and"
40507,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.098039216,"the, to, as, sars-cov-2, and"
40508,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.098039216,"to, sars-cov-2, in, and, from"
40509,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.098039216,"sars-cov-2, has, the, and, to"
40510,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.098039216,"from, to, and, the, species"
40511,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.098039216,"of, the, from, in, and"
40512,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.098039216,"to, the, from, an, and"
40513,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.098039216,"in, of, sars-cov-2, were, to"
40514,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.098039216,"the, coronaviruses, in, with, sars-cov-2"
40515,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.098039216,"the, and, is, to, in"
40516,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.098039216,"is, and, at, the, in"
40517,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.098039216,"similar, nucleotide, and, from, ratg13"
40518,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.098039216,"that, the, and, may, of"
40519,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.098039216,"to, suggest, that, in, than"
40520,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.098039216,"that, the, and, may, to"
40521,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.098039216,"has, found, the, to, in"
40522,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.098039216,"a, sars-cov-2, and, the, in"
40523,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.098039216,"the, sars-cov-2, to, ace2, a"
40524,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.098039216,"to, by, is, sars-cov-2, the"
40525,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.098039216,"may, the, of, for, also, to, species, by, is, and"
40526,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.098039216,"the, and, for, of, to, is, between, sars-cov-2, be, by"
40527,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.098039216,"cross, between, and, may, the"
40528,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.098039216,"the, was, to, and, that"
40529,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.098039216,"the, was, to, that, of"
40530,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.098039216,"the, earliest, cases, with, were"
40531,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.098039216,"of, the, from, in, 2020"
40532,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.098039216,"sars-cov-2, bat, to, coronavirus, in"
40533,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.098039216,"of, that, the, from, in"
40534,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.098039216,"that, sars-cov-2, from, the, in"
40535,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.098039216,"that, the, in, market, of"
40536,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.098039216,"that, sars-cov-2, the, of, from"
40537,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.098039216,"of, sars-cov-2, in, the, for"
40538,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.098039216,"are, of, the, which, bats"
40539,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.098039216,"the, sars-cov-2, is, of, genome"
40540,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.098039216,"that, is, covid-19, from, a"
40541,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.098039216,"the, covid-19, genome, that, a"
40542,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.098039216,"a, is, to, in, the"
40543,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.098039216,"the, a, virus, in, covid-19"
40544,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.098039216,"the, of, and, more, or"
40545,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.098039216,"the, of, viruses, sars, and"
40546,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.098039216,"the, of, bats, as, and"
40547,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.098039216,"to, the, sars-cov-2, and, as"
40548,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.098039216,"of, and, bat, species, the"
40549,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.098039216,"in, the, an, and, of"
40550,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.098039216,"the, of, and, in, to"
40551,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.098039216,"the, species, of, bat, and"
40552,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.098039216,"the, in, and, china,, of"
40553,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.098039216,"species, and, in, by, the"
40554,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.098039216,"the, of, and, this, viruses"
40555,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.098039216,"that, a, bat, in, of"
40556,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.098039216,"the, viruses, closely, to, of"
40557,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.098039216,"of, the, marshall.senate.gov, origins, covid-19"
40558,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.098039216,"of, but, that, the, a"
40559,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.098039216,"from, to, have, shared, common"
40560,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.098039216,"genome, the, to, bat, sars-cov-2"
40561,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.098039216,"the, sars-cov-2, at, as, by"
40562,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.098039216,"the, sars-cov-2, to, is, by"
40563,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.098039216,"at, bat, is, the, sars-cov-2"
40564,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.098039216,"sars-cov-2, with, other, and, a"
40565,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.098039216,"other, along, with, a, sars-cov-2"
40566,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.098039216,"in, the, both, and, a"
40567,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.098039216,"the, of, closely, viruses, to"
40568,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.098039216,"of, three, the, spike, to"
40569,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.098039216,"the, of, that, to, and"
40570,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.098039216,"of, the, that, have, to"
40571,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.098039216,"suggest, that, to, than, in"
40572,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.098039216,"is, and, to, the, viruses"
40573,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.098039216,"the, is, to, at, which"
40574,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.098039216,"the, of, is, to, by"
40575,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.098039216,"to, of, is, related, bat"
40576,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.098039216,"the, of, marshall.senate.gov, origins, covid-19"
40577,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.098039216,"with, a, and, the, in"
40578,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.098039216,"the, to, are, more, closely, related, in, than, and, sars-cov-2"
40579,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.098039216,"the, to, bat, and, a"
40580,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.098039216,"a, the, sars-cov-2, with, and"
40581,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.098039216,"sars-cov-2, to, the, in, these"
40582,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.098039216,"in, the, recombination, and, bat"
40583,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.098039216,"in, the, is, sars-cov-2, that"
40584,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.098039216,"a, of, by, at, the"
40585,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.098039216,"the, of, to, species, may, is, also, for, and, by"
40586,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.098039216,"the, to, isolated, in, from, an, of, a, horseshoe, (rhinolophus"
40587,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.098039216,"the, and, for, of, a, or, to, that, were, infections, in, sars, those, civets,, be"
40588,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.098039216,"the, genome, to, and, that, sequence, a, high, percentage, not"
40589,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.098039216,"the, genome, of, coronavirus, more, than, to, bat, previously, for"
40590,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.098039216,"the, of, bats, were, a, for, genome, two, from, and"
40591,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.098039216,"this, its, in, the, of, that, was, to, similar, virus"
40592,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.098039216,"in, the, market, live, animal, and, a, presence, of, animals"
40593,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.098039216,"in, one, spread, the, of, multiple, that, a, animals, to"
40594,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.098039216,"the, of, sars-cov-2, to, be, is, for, and, between, by"
40595,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.098039216,"to, the, sars, were, for, be, infections, and, a, in, of, that, those, or, civets,"
40596,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.098039216,"the, of, with, however,, a, much, and, more, sars-cov-2, or"
40597,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.098039216,"at, this, is, the, with, sars-cov-2, that, more, for, than"
40598,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.098039216,"covid-19, be, a, in, the, that, sars-cov-2, animal, or, for"
40599,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.098039216,"the, shows, of, and, to"
40600,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.098039216,"a, the, and, to, is"
40601,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.098039216,"the, to, that, and, animal"
40602,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.098039216,"the, and, but, also, in"
40603,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.098039216,"that, the, to, with, a"
40604,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.098039216,"in, to, sars-cov-2, from, and"
40605,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.098039216,"a, of, the, in, to"
40606,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.098039216,"a, to, in, the, and"
40607,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.098039216,"a, the, bat, in, its"
40608,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.098039216,"that, sars-cov-2, to, the, natural"
40609,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.098039216,"the, natural, likely, to, that"
40610,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.098039216,"of, the, spike, protein, a"
40611,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.098039216,"the, of, natural, a, human"
40612,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.098039216,"that, or, the, sars-cov-2, on"
40613,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.098039216,"a, that, is, related, of"
40614,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.098039216,"of, the, bat, that, bats"
40615,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.098039216,"human, to, in, a, which"
40616,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.098039216,"the, is, to, a, in"
40617,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.098039216,"overall, ratg13,, that, human, a"
40618,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.098039216,"the, that, is, a, in"
40619,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.098039216,"the, is, it, not, to"
40620,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.098039216,"all, sars-cov-2, to, coronaviruses, the"
40621,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.098039216,"for, sars-cov-2, similarity, the, in"
40622,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.098039216,"can, that, natural, and, the"
40623,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.098039216,"the, of, a, and, which"
40624,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.098039216,"by, and, the, of, natural"
40625,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.098039216,"can, that, virus, to, the"
40626,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.098039216,"the, in, to, very, of"
40627,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.098039216,"sars-cov-2, the, of, virus, in"
40628,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.098039216,"to, the, that, an, this"
40629,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.098039216,"the, or, more, of, and"
40630,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.098039216,"with, the, and, of, a, or, however,, sars-cov-2, much, more"
40631,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.098039216,"and, pangolins, the, from, or"
40632,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.098039216,"is, the, in, rbd, of"
40633,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.098039216,"is, to, in, human, and"
40634,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.098039216,"to, have, from, common, shared"
40635,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.098039216,"to, the, and, not, a, high, percentage, sequence, that, genome"
40636,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.098039216,"covid-19, a, the, that, but"
40637,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.098039216,"the, of, most, a, that"
40638,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.098039216,"a, virus, that, originated, the"
40639,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.098039216,"the, covid-19, a, virus, in"
40640,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.098039216,"the, that, virus, found, in"
40641,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.098039216,"the, viruses, of, sars, and"
40642,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.098039216,"to, the, and, sars-cov, mers-cov"
40643,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.098039216,"to, the, in, and, bats"
40644,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.098039216,"evidence, that, the, covid-19, from"
40645,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.098039216,"the, for, of, from, intermediate"
40646,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.098039216,"of, the, possible, existence, covid-19"
40647,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.098039216,"the, evidence, from, that, covid-19"
40648,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.098039216,"that, or, the, hosts, for"
40649,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.098039216,"of, and, china,, in, the"
40650,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.098039216,"to, and, of, that, in"
40651,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.098039216,"a, coronaviruses, are, of, common"
40652,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.098039216,"most, that, was, the, of"
40653,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.098039216,"in, have, similar, to, and"
40654,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.098039216,"of, the, outbreak, that, bats"
40655,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.098039216,"viruses, have, in, rhinolophus, bats"
40656,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.098039216,"the, to, was, in, of"
40657,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.098039216,"the, species, of, that, rhinolophus"
40658,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.098039216,"of, viruses, in, and, the"
40659,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.098039216,"and, bat, some, the, of"
40660,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.098039216,"transmission, of, and, with, or"
40661,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.098039216,"and, to, the, bats, be"
40662,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.098039216,"the, in, bats, and, humans"
40663,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.098039216,"and, by, the, was, in"
40664,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.098039216,"and, by, species, in, the"
40665,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.098039216,"the, of, in, is, origin"
40666,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.098039216,"the, obtained, from, sars-cov-2, and"
40667,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.098039216,"the, of, from, virus, with"
40668,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.098039216,"the, cross, may, and, between"
40669,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.098039216,"the, from, pangolins, and, or"
40670,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.098039216,"in, the, from, or, during"
40671,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.098039216,"the, may, have, an, intermediate"
40672,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.098039216,"is, a, which, the, from"
40673,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.098039216,"the, and, by, a, that"
40674,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.098039216,"that, species, of, rhinolophus, the"
40675,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.098039216,"the, most, that, from, as"
40676,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.098039216,"ratg13,, a, overall, that, human"
40677,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.098039216,"the, to, of, for, and"
40678,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.098039216,"a, was, likely, of, we"
40679,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.098039216,"virus, has, been, of, origin"
40680,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.098039216,"sars-cov-2, that, to, it, from"
40681,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.098039216,"that, with, the, of, an"
40682,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.098039216,"that, in, species,, such, as"
40683,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.098039216,"studies, that, sars-cov-2, to, humans"
40684,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.098039216,"that, the, of, but, a"
40685,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.098039216,"that, humans, in, sars-cov-2, species"
40686,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.098039216,"that, virus, natural, and, the"
40687,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.098039216,"a, and, the, of, virus"
40688,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.098039216,"the, of, human, a, and"
40689,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.098039216,"the, has, a, of, and"
40690,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.098039216,"the, of, human, natural, a"
40691,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.098039216,"in, the, initial, and, of"
40692,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.098039216,"and, have, is, by, of"
40693,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.098039216,"and, the, of, by, natural"
40694,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.098039216,"the, is, a, bat, ratg13,"
40695,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.098039216,"a, the, in, its, bat"
40696,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.098039216,"the, which, a, from, is"
40697,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.098039216,"in, coronaviruses, sequences, to, and"
40698,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.098039216,"that, bats, and, are, sars-cov-2"
40699,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.098039216,"the, as, that, most, from"
40700,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.098039216,"to, that, the, from, this"
40701,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.098039216,"an, from, to, and, the"
40702,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.098039216,"the, an, to, that, this"
40703,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.098039216,"ratg13, is, the, to, be"
40704,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.098039216,"nucleotide, and, from, similar, ratg13"
40705,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.098039216,"and, of, sars-cov-2, ratg13, their"
40706,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.098039216,"was, the, in, animals, of"
40707,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.098039216,"to, in, sars-cov-2, these, the"
40708,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.098039216,"this, the, of, that, to"
40709,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.098039216,"the, sars-cov-2, on, or, that"
40710,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.098039216,"that, the, hosts, or, for"
40711,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.098039216,"results, that, sars-cov-2, from, the"
40712,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.098039216,"the, sars-cov-2, obtained, from, and"
40713,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.098039216,"bat, the, cluster, sars-cov-2, that"
40714,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.098039216,"also, that, the, pangolin, to"
40715,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.098039216,"bats, are, that, sars-cov-2, and"
40716,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.098039216,"t, also, that, the, virus"
40717,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.098039216,"that, the, covid-19, virus, genome"
40718,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.098039216,"virus, is, to, in, genome"
40719,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.098039216,"is, that, of, a, related"
40720,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.098039216,"the, a, similar, to, that"
40721,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.098039216,"the, of, sequences, sars-cov-2, by"
40722,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.098039216,"the, by, a, at, of"
40723,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.098039216,"in, at, sars-cov-2, the, of"
40724,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.098039216,"sars-cov-2, their, and, is, a"
40725,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.098039216,"to, the, sars-cov-2, a, of"
40726,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.098039216,"is, in, a, an, to"
40727,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.098039216,"of, sars-cov-2, and, their, ratg13"
40728,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.098039216,"the, for, a, of, and"
40729,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.098039216,"two, of, in, and, to"
40730,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.098039216,"to, have, in, pangolin, which"
40731,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.098039216,"the, for, of, sars-cov-2, intermediate"
40732,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.098039216,"of, the, in, with, and"
40733,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.098039216,"on, the, that, and, to"
40734,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.098039216,"that, the, viruses, to, or"
40735,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.098039216,"the, that, closest, and, to"
40736,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.098039216,"the, sars-cov-2, bats, this, is"
40737,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.098039216,"bat, is, sars-cov-2, at, the"
40738,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.098039216,"with, the, for, that, this, is, sars-cov-2, more, than, at"
40739,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.098039216,"the, that, sars-cov-2, cluster, bat"
40740,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.098039216,"that, the, bats, and, from"
40741,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.098039216,"the, of, bats, from, and"
40742,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.098039216,"this, of, and, viruses, the"
40743,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.098039216,"we, between, sars-cov-2, and, the, to, pangolin, in, that, bat"
40744,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.098039216,"viruses, to, and, the, is"
40745,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.098039216,"in, the, bat, between, and"
40746,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.098039216,"in, pangolin, which, have, to"
40747,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.098039216,"between, sars-cov-2, and, the, bat"
40748,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.098039216,"sars-cov-2, that, the, with, or"
40749,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.098039216,"of, the, those, in, virus"
40750,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.098039216,"and, bat, the, between, in"
40751,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.098039216,"cov, sars-cov-2, with, more, than"
40752,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.098039216,"the, sars-cov, of, identity, with"
40753,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.098039216,"for, the, of, evidence, that"
40754,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.098039216,"the, recombination, of, for, and"
40755,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.098039216,"in, the, host,, and, a"
40756,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.098039216,"in, a, and, both, the"
40757,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.098039216,"that, the, have, a, of"
40758,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.098039216,"and, a, of, the, for"
40759,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.098039216,"sars-cov-2, more, with, cov, than"
40760,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.098039216,"with, the, sars-cov-2, and, similarity"
40761,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.098039216,"natural, of, the, in, that"
40762,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.098039216,"shows, and, to, of, the"
40763,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.098039216,"closest, to, the, and, that"
40764,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.098039216,"it, that, the, in, of"
40765,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.098039216,"recombination, in, the, bat, and"
40766,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.098039216,"the, to, sars-cov-2, genome,, of"
40767,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.098039216,"the, virus, to, from, a"
40768,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.098039216,"by, virus, with, the, of"
40769,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.098039216,"with, the, of, a, from"
40770,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.098039216,"that, from, to, is, sars-cov-2"
40771,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.098039216,"and, be, intermediate, sars-cov-2, the"
40772,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.098039216,"the, of, that, animal, sars-cov-2"
40773,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.098039216,"a, is, in, the, that"
40774,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.098039216,"the, that, animal, in, covid-19"
40775,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.098039216,"the, sars-cov-2, from, in, be"
40776,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.098039216,"the, sars-cov-2, in, from, a"
40777,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.098039216,"the, for, a, or, that, covid-19, in, sars-cov-2, animal, be"
40778,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.098039216,"the, covid-19, that, a, but"
40779,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.098039216,"during, the, from, or, in"
40780,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.098039216,"the, from, that, sars-cov-2, a"
40781,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.098039216,"it, the, and, to, is"
40782,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.098039216,"the, and, of, is, to"
40783,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.098039216,"is, to, the, it, not"
40784,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.098039216,"a, to, that, of, sars-cov-2"
40785,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.098039216,"that, in, patients, were, a"
40786,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.098039216,"of, be, to, suggesting, that"
40787,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.098039216,"in, of, were, to, sars-cov-2"
40788,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.098039216,"in, of, to, that, sars-cov-2"
40789,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.098039216,"coronavirus, to, be, in, of"
40790,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.098039216,"that, to, a, human, zoonotic"
40791,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.098039216,"infectious, of, are, hosts, and"
40792,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.098039216,"in, the, which, has, was"
40793,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.098039216,"in, the, was, that, to"
40794,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.098039216,"that, was, sars-cov-2, to, in"
40795,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.098039216,"in, the, protein, of, that"
40796,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.098039216,"the, three, to, of, spike"
40797,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.098039216,"that, natural, in, the, of"
40798,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.098039216,"sequence, the, of, bat, in"
40799,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.098039216,"the, rbd, in, of, is"
40800,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.098039216,"is, to, the, ratg13, be"
40801,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.098039216,"in, of, to, be, coronavirus"
40802,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.098039216,"coronaviruses, are, a, of, common"
40803,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.098039216,"of, related, to, is, bat"
40804,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.098039216,"that, in, and, to, of"
40805,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.098039216,"the, to, evidence, of, found"
40806,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.098039216,"also, found, to, suggesting, that"
40807,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.098039216,"that, the, of, evidence, to"
40808,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.098039216,"an, intermediate, may, have, the"
40809,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.098039216,"with, the, of, that, an"
40810,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.098039216,"the, that, to, also, pangolin"
40811,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.098039216,"some, of, and, the, bat"
40812,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.097902098,"the, first, animal, of, that, for, as, at, to, by, a, coronavirus, is, evidence"
40813,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.097902098,"that, to, as, at, first, the, animal, coronavirus, by, a, of, is, evidence, for"
40814,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.097826087,"the, and, of, a, to, is, sars-cov-2, animal, be"
40815,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.097826087,"and, the, to, as, that, into, for, can, virus"
40816,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.097826087,"the, that, in, for, to, and, health, with, a"
40817,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.097826087,"to, this, the, humans, of, is, has, been, evidence"
40818,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.097826087,"could, several, species, are, to, as, and, in, been"
40819,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.097826087,"the, viruses, that, to, are, mutations, of, sars-cov-2, at"
40820,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.097826087,"a, at, the, of, and, in, we, that, were"
40821,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.097826087,"the, has, been, to, humans, evidence, of, this, is"
40822,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.097826087,"he, coronavirus, to, as, by, genetic, is, at, the"
40823,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.097826087,"is, that, in, to, and, experts, not, known, an"
40824,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.097826087,"viruses, are, at, mutations, to, that, the, of, sars-cov-2"
40825,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.097826087,"is, the, coronavirus, known, to, its, in, of, than"
40826,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.097826087,"the, animals, to, in, wet, a, as, that, market"
40827,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.097826087,"a, of, the, we, that, and, at, in, were"
40828,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.097826087,"the, of, all, a, that, there, no, is, at"
40829,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.097826087,"we, for, between, and, that, in, the, of, sars-cov-2"
40830,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.097826087,"bat, and, the, they, are, into, clusters, cluster, with"
40831,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.097826087,"to, as, at, he, the, coronavirus, by, genetic, is"
40832,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.097826087,"the, that, in, a, as, to, animals, wet, market"
40833,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.097826087,"in, the, a, that, to, and, with, for, health"
40834,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.097826087,"that, experts, not, an, to, and, is, known, in"
40835,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.097826087,"sars-cov-2, is, to, be, a, of, animal, and, the"
40836,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.097826087,"there, is, no, at, all, that, the, of, a"
40837,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.097826087,"and, from, in, be, that, the, of, likely, sars-cov-2"
40838,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.097826087,"could, been, to, are, as, several, and, in, species"
40839,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.097826087,"in, the, by, and, to, that, sars-cov-2, of, as"
40840,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.097826087,"the, by, of, in, and, that, this, natural, than"
40841,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.097826087,"that, than, the, by, in, this, of, natural, and"
40842,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.097826087,"as, and, to, by, the, of, that, sars-cov-2, in"
40843,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.097826087,"and, the, bat, clusters, are, cluster, they, with, into"
40844,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.097826087,"we, between, sars-cov-2, and, of, the, in, that, for"
40845,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.097826087,"and, the, be, likely, that, of, sars-cov-2, in, from"
40846,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.097826087,"the, known, to, coronavirus, in, is, than, its, of"
40847,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.097744361,"this, that, a, the, virus, into, with, of, in, different, also, contact, to"
40848,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.097744361,"the, of, also, to, a, different, with, that, into, contact, this, in, virus"
40849,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.097744361,"the, that, in, for, researchers, of, were, to, by, chinese, and, with, a"
40850,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.097744361,"the, that, in, for, researchers, of, to, by, and, with, a, known, an"
40851,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.097744361,"by, the, of, a, in, to, that, with, and, were, researchers, for, chinese"
40852,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.097744361,"the, for, to, a, that, with, and, researchers, by, in, of, known, an"
40853,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.097560976,"numerous, and, are, to"
40854,"In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.097560976,"in, to, viruses, human"
40855,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.097560976,"a, sars-cov-2, genetic, in"
40856,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.097560976,"the, of, human, from"
40857,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.097560976,"the, virus, and, viruses"
40858,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.097560976,"from, humans, and, the"
40859,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.097560976,"the, horseshoe, bats, as"
40860,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.097560976,"the, from, viruses, bats"
40861,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.097560976,"and, are, to, numerous"
40862,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.097560976,"to, and, of, sars-cov-2"
40863,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.097560976,"many, in, and, of"
40864,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.097560976,"species,, to, sars-cov-2, in"
40865,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.097560976,"of, and, from, bats"
40866,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.097560976,"of, genetic, sequences, from"
40867,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.097560976,"the, very, similar, to"
40868,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.097560976,"is, more, sars-cov-2, to"
40869,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.097560976,"virus, in, is, sars-cov-2"
40870,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.097560976,"a, coronavirus, that, about"
40871,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.097560976,"of, have, a, sars-cov-2"
40872,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.097560976,"the, in, scientific, and, that, for, a, of"
40873,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.097560976,"that, the, covid-19, virus, in, and, to, of"
40874,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.097560976,"that, sars-cov-2, has, the, of, virus, and, to"
40875,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.097560976,"in, the, of, a, found, to, human, and"
40876,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.097560976,"genetic, and, that, is"
40877,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.097560976,"is, many, other, and"
40878,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.097560976,"the, identical, to, that"
40879,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.097560976,"as, to, the, bat"
40880,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.097560976,"to, have, with, sars-cov-2"
40881,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.097560976,"of, a, the, was"
40882,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.097560976,"a, the, sequence, sars-cov-2"
40883,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.097560976,"a, of, bat, sars-cov-2"
40884,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.097560976,"virus, has, of, and"
40885,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.097560976,"and, of, natural, origin"
40886,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.097560976,"natural, of, origin, and"
40887,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.097560976,"results, of, bat, genome"
40888,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.097560976,"of, virus, has, been"
40889,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.097560976,"that, the, human, bat"
40890,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.097560976,"the, was, to, human"
40891,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.097560976,"relatives, of, with, sars-cov-2"
40892,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.097560976,"sars-cov-2, with, of, and"
40893,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.097560976,"and, the, of, bat, to, with, in, is"
40894,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.097560976,"of, in, the, known"
40895,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.097560976,"are, similar, to, sars-cov-2"
40896,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.097560976,"are, to, genomic, sars-cov-2"
40897,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.097560976,"of, the, that, reservoirs"
40898,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.097560976,"that, bats, the, its"
40899,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.097560976,"the, of, in, receptor, and, that, coronavirus, a"
40900,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.097560976,"a, virus, the, was"
40901,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.097560976,"human, in, to, the"
40902,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.097560976,"a, the, sequence, similarity"
40903,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.097560976,"that, the, a, discovered"
40904,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.097560976,"the, a, human, and"
40905,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.097560976,"the, bats, hosts, for"
40906,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.097560976,"that, animal, origin, is"
40907,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.097560976,"origin, of, likely, on"
40908,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.097560976,"suggested, the, of, animal"
40909,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.097560976,"and, to, in, a"
40910,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.097560976,"the, of, an, is"
40911,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.097560976,"and, species, the, of"
40912,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.097560976,"shown, that, the, of"
40913,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.097560976,"that, of, the, gene"
40914,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.097560976,"of, the, bats, reservoirs"
40915,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.097560976,"are, the, and, bats"
40916,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.097560976,"virus, that, from, to"
40917,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.097560976,"the, is, highly, to"
40918,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.097560976,"to, a, sequence, from"
40919,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.097560976,"to, severe, respiratory, the"
40920,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.097560976,"coronaviruses, to, including, and"
40921,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.097560976,"the, was, to, and"
40922,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.097560976,"the, to, and, spread"
40923,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.097560976,"the, in, geographic, and"
40924,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.097560976,"that, the, of, in"
40925,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.097560976,"in, the, bat, of"
40926,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.097560976,"the, of, that, reservoirs"
40927,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.097560976,"the, sars-cov-2, bats, are"
40928,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.097560976,"be, the, sars-cov-2, animal"
40929,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","with the first case being linked to  

a seafood market",0.097560976,"a, to, with, the"
40930,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.097560976,"is, evidence, the, of"
40931,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.097560976,"evidence, sars-cov-2, has, is"
40932,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.097560976,"this, the, is, of"
40933,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.097560976,"the, in, origin, and"
40934,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.097560976,"a, virus, by, the"
40935,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.097560976,"the, that, was, not"
40936,"atural  

selection in an animal host before zoonotic  

transfer;","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.097560976,"in, an, animal, host"
40937,The COVID-19 most likely developed from bat origin coronaviruses,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.097560976,"likely, from, bat, coronaviruses"
40938,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.097560976,"the, of, to, as, a, that, into, result"
40939,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.097560976,"the, natural, that, and"
40940,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.097560976,"the, natural, has, and"
40941,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.097560976,"of, the, that, coronavirus"
40942,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.097560976,"have, at, the, wuhan"
40943,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.097560976,"sars-cov-2, the, that, of"
40944,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.097560976,"from, bats, of, and"
40945,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.097560976,"of, sars-cov-2, and, from"
40946,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.097560976,"that, from, a, to"
40947,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.097560976,"of, sars-cov-2, from, bat"
40948,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.097560976,"in, which, are, that, of, sars-cov-2, both, and"
40949,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.097560976,"the, into, from, market"
40950,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.097560976,"sars-cov-2, from, intermediate, host"
40951,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.097560976,"the, sars-cov-2, at, of"
40952,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.097560976,"huanan, the, and, of"
40953,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.097560976,"that, the, sars-cov-2, and"
40954,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.097560976,"that, in, a, market"
40955,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.097560976,"the, in, market, that"
40956,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.097560976,"the, to, are, a, closely, related, that, in"
40957,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.097560976,"that, study, are, in"
40958,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.097560976,"of, the, huanan, and"
40959,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.097560976,"and, the, of, a, with, this, in, is"
40960,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.097560976,"the, in, of, this"
40961,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.097560976,"the, from, at, market"
40962,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.097560976,"et, al., the, at"
40963,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.097560976,"virus, by, was, the"
40964,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.097560976,"the, at, of, virus"
40965,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.097560976,"the, of, was, from"
40966,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.097560976,"the, of, been, coronavirus"
40967,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.097560976,"the, and, from, animal"
40968,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.097560976,"animal, and, in, the"
40969,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.097560976,"the, and, other, been"
40970,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.097560976,"the, to, in, human"
40971,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.097560976,"to, the, because, human"
40972,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.097560976,"to, in, the, human"
40973,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.097560976,"the, at, market, that"
40974,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.097560976,"the, within, genomic, that"
40975,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.097560976,"and, was, the, sars-cov-2"
40976,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.097560976,"the, likely, that, reservoir"
40977,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.097560976,"the, that, sars-cov-2, was"
40978,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.097560976,"sars-cov-2, from, humans, to"
40979,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.097560976,"in, to, of, at"
40980,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.097560976,"to, at, in, on"
40981,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.097560976,"that, sars-cov-2, a, with"
40982,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.097560976,"other, that, sars-cov-2, a"
40983,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.097560976,"a, the, that, in"
40984,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.097560976,"and, of, the, huanan"
40985,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.097560976,"the, of, re-, that"
40986,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor",0.097560976,"a, sars-cov-2, recently, to"
40987,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.097560976,"are, viruses, to, the, in, and, be, for"
40988,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.097560976,"there, is, that, sars-cov-2"
40989,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.097560976,"the, that, be, as"
40990,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.097560976,"that, from, the, animals"
40991,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.097560976,"that, in, a, wuhan"
40992,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.097560976,"in, an, from, to"
40993,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.097560976,"a, that, to, in"
40994,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.097560976,"the, of, and, that, a, evidence, likely, to"
40995,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.097560976,"and, the, likely, that, was, of, sars-cov-2, a"
40996,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.097560976,"and, to, was, the, of, that, sars-cov-2, a"
40997,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.097560976,"that, about, a, coronavirus"
40998,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.097560976,"about, the, to, that"
40999,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.097560976,"the, virus, 70%, and"
41000,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.097560976,"the, that, has, a"
41001,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.097560976,"was, has, the, with"
41002,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.097560976,"the, that, from, animals"
41003,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.097560976,"the, from, and, were"
41004,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.097560976,"and, this, the, that"
41005,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.097560976,"that, of, to, a"
41006,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.097560976,"a, to, that, and"
41007,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.097560976,"a, that, and, to"
41008,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.097560976,"that, of, to, coronaviruses"
41009,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.097560976,"the, of, and, host"
41010,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.097560976,"in, the, case, and"
41011,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.097560976,"and, the, that, a"
41012,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.097560976,"and, that, a, the"
41013,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.097560976,"the, a, in, nature"
41014,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.097560976,"the, of, been, to"
41015,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.097560976,"a, intermediate, sars-cov-2, the"
41016,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.097560976,"from, as, was, the"
41017,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Bats have been reported as being the rich source of 

coronaviruses",0.097560976,"have, been, of, the"
41018,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.097560976,"a, the, sars-cov-2, from"
41019,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.097560976,"he, of, sars-cov-2, the"
41020,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.097560976,"the, sars-cov-2, similar, to"
41021,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.097560976,"the, isolated, from, with"
41022,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.097560976,"the, ratg13, has, from"
41023,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.097560976,"the, of, genetic, that"
41024,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.097560976,"and, the, of, to, a, that, recombination, virus"
41025,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.097560976,"the, of, to, pangolin"
41026,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.097560976,"is, to, the, human"
41027,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.097560976,"of, pangolin, and, to"
41028,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.097560976,"the, from, food, market"
41029,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.097560976,"the, to, bats, its"
41030,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.097560976,"from, a, to, in"
41031,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.097560976,"the, that, about, to"
41032,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.097560976,"the, to, covid-19, most"
41033,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.097560976,"the, that, of, to"
41034,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.097560976,"virus, has, in, bats"
41035,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.097560976,"the, evidence, of, is"
41036,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.097560976,"as, is, at, the"
41037,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.097560976,"the, that, all, a"
41038,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.097560976,"that, natural, and, the"
41039,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.097560976,"the, to, likely, that"
41040,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.097560976,"the, to, animals, likely"
41041,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.097560976,"the, to, in, is, that, virus, animal, and"
41042,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.097560976,"in, and, similar, to"
41043,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.097560976,"the, huanan, and, of"
41044,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.097560976,"with, the, sars-like, and"
41045,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.097560976,"in, been, the, from"
41046,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.097560976,"to, at, the, huanan, seafood, market, on, december"
41047,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.097560976,"the, to, severe, respiratory"
41048,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.097560976,"at, the, market, from"
41049,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.097560976,"bats, the, reservoirs, of"
41050,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.097560976,"coronavirus, been, the, of"
41051,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.097560976,"of, to, the, been"
41052,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.097560976,"sars-cov-2, to, the, over"
41053,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.097560976,"of, to, the, sars-cov-2"
41054,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.097560976,"the, a, host, to"
41055,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.097560976,"that, and, for, sars-cov-2"
41056,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.097560976,"human, from, of, the"
41057,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.097560976,"the, bat, that, human"
41058,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.097560976,"that, of, from, the"
41059,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.097560976,"of, the, been, from"
41060,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.097560976,"bat, the, that, are"
41061,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.097560976,"the, that, from, human"
41062,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.097560976,"are, a, of, the"
41063,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.097560976,"a, in, the, protein"
41064,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.097560976,"genetic, and, is, that"
41065,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.097560976,"of, that, sars-cov, and"
41066,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.097560976,"of, and, sars-cov, bat"
41067,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.097560976,"has, the, virus, in"
41068,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.097560976,"from, that, virus, to"
41069,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.097560976,"that, a, zoonotic, virus, an, animal, human, to"
41070,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.097560976,"a, to, that, zoonotic"
41071,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.097560976,"to, a, the, is"
41072,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.097560976,"the, is, to, virus"
41073,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.097560976,"sars-cov-2, humans, from, to"
41074,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.097560976,"the, coronaviruses, from, sars-cov-2"
41075,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.097560976,"in, the, of, from"
41076,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.097560976,"is, to, cause, the"
41077,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.097560976,"have, genetic, that, bat"
41078,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.097560976,"virus, to, the, and"
41079,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.097560976,"that, animal, is, origin"
41080,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.097560976,"sars-cov-2, has, evidence, is"
41081,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.097560976,"that, evidence, a, and"
41082,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.097560976,"and, that, a, not"
41083,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.097560976,"in, virus, has, bats"
41084,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.097560976,"and, the, from, animal"
41085,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.097560976,"is, more, to, sars-cov-2"
41086,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.097560976,"the, to, from, of"
41087,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.097560976,"of, to, genome, from"
41088,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.097560976,"zoonotic, and, in, the"
41089,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.097560976,"to, that, and, the"
41090,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.097560976,"the, and, zoonotic, to"
41091,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.097560976,"the, that, are, to"
41092,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.097560976,"human, with, are, of"
41093,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.097560976,"is, highly, the, to"
41094,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.097560976,"that, the, coronavirus, of"
41095,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.097560976,"has, and, the, of"
41096,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.097560976,"the, of, with, bat"
41097,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.097560976,"the, and, with, of"
41098,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.097560976,"the, that, of, has"
41099,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.097560976,"the, of, has, and"
41100,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.097560976,"that, a, genome, sars-cov-2"
41101,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.097560976,"sars-cov-2, a, natural, and"
41102,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.097560976,"that, a, sars-cov-2, through"
41103,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.097560976,"at, the, et, al."
41104,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.097560976,"the, that, sars-, and"
41105,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.097560976,"the, virus, and, 70%"
41106,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.097560976,"the, of, virus, and"
41107,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.097560976,"indicated, that, a, in"
41108,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.097560976,"a, and, in, humans"
41109,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.097560976,"the, seafood, market, in"
41110,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.097560976,"of, the, which, and"
41111,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.097560976,"the, and, is, which"
41112,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.097560976,"in, a, that, market"
41113,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.097560976,"that, in, wuhan, a"
41114,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.097560976,"that, to, identical, the"
41115,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.097560976,"the, genomic, within, that"
41116,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.097560976,"revealed, the, from, and"
41117,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.097560976,"sars-cov-2, in, that, is"
41118,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.097560976,"is, that, from, this"
41119,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.097560976,"and, that, sars-cov, of"
41120,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.097560976,"revealed, a, of, the"
41121,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.097560976,"and, the, are, sars-cov-2"
41122,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.097560976,"the, are, of, to"
41123,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.097560976,"in, and, to, that, sars-cov-2, is, bat, as"
41124,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.097560976,"the, sequence, sars-cov-2, a"
41125,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.097560976,"the, which, a, from"
41126,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.097560976,"at, of, in, to"
41127,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.097560976,"the, of, a, to"
41128,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.097560976,"the, that, in, with"
41129,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.097560976,"genome, with, that, a"
41130,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.097560976,"to, in, the, with"
41131,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.097560976,"the, of, a, host"
41132,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.097560976,"of, are, human, with"
41133,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.097560976,"sars-cov-2, with, the, of"
41134,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.097560976,"the, are, sars-cov-2, with"
41135,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.097560976,"of, sars-cov-2, infected, with"
41136,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.097560976,"have, the, at, wuhan"
41137,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.097560976,"at, in, to, on"
41138,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.097560976,"the, huanan, seafood, at, on, december, market, to"
41139,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.097560976,"at, in, the, to"
41140,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.097560976,"the, at, is, in"
41141,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.097560976,"sars-cov-2, to, the, cov"
41142,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.097560976,"sars-cov-2, spike, ace2, a"
41143,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.097560976,"a, pangolin, and, sars-cov-2"
41144,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.097560976,"and, in, of, many"
41145,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.097560976,"of, for, a, scientific, that, in, and, the"
41146,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.097560976,"that, a, in, of"
41147,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.097560976,"that, the, for, a"
41148,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.097560976,"the, and, pangolin, of"
41149,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.097560976,"a, for, the, and"
41150,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.097560976,"have, of, in, as"
41151,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.097560976,"the, of, natural, for"
41152,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.097560976,"of, viruses, in, the"
41153,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.097560976,"the, as, of, and"
41154,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.097560976,"and, the, of, from"
41155,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.097560976,"sars-cov-2, a, natural, the"
41156,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.097560976,"the, pangolin, to, of"
41157,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.097560976,"the, we, believe, than"
41158,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.097560976,"a, the, human, laboratory"
41159,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.097560976,"a, the, virus, by"
41160,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.097560976,"the, of, new, a"
41161,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.097560976,"a, of, china, coronaviruses"
41162,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K",0.097560976,"more, to, with, than"
41163,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.097560976,"and, bat, the, in"
41164,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.097560976,"the, sars-cov-2, and, viruses"
41165,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.097560976,"the, to, in, of"
41166,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.097560976,"with, sars-like, and, the"
41167,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.097560976,"the, a, host, of"
41168,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.097560976,"sars-cov-2, in, a, genetic"
41169,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.097560976,"sars-cov-2, a, the, intermediate"
41170,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.097560976,"the, sars-cov-2, a, in"
41171,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.097560976,"the, in, with, were"
41172,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.097560976,"with, cov, sars-cov-2, a"
41173,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.097560976,"to, bat, as, the"
41174,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.097560976,"because, human, to, the"
41175,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.097560976,"a, the, be, to"
41176,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.097560976,"that, the, of, covid-19"
41177,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.097560976,"virus, the, was, by"
41178,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.097560976,"the, in, sars-cov-2, not"
41179,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.097560976,"sars-cov-2, from, coronaviruses, the"
41180,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.097560976,"of, the, sars-cov-2, coronaviruses"
41181,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.097560976,"genome, that, sars-cov-2, a"
41182,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.097560976,"in, that, a, of"
41183,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.097560976,"horseshoe, of, sars-cov-2, bat"
41184,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.097560976,"of, virus, bat, strain"
41185,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.097560976,"that, sars-cov-2, found, in"
41186,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.097560976,"that, of, sars-cov-2, has"
41187,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.097560976,"of, a, virus, with"
41188,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.097560976,"sars-cov-2, the, that, to"
41189,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.097560976,"from, to, the, human"
41190,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.097560976,"a, of, by, the"
41191,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.097560976,"that, not, a, host"
41192,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.097560976,"the, of, that, not"
41193,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.097560976,"the, group, of, is"
41194,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.097560976,"of, to, found, in"
41195,"Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.097560976,"also, from, the, as"
41196,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.097560976,"in, from, an, to"
41197,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.097560976,"in, the, from, and"
41198,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.097560976,"the, show, with, bat"
41199,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.097560976,"of, has, sars-cov-2, the"
41200,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.097560976,"sars-cov-2, ratg13, the, of"
41201,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.097560976,"the, not, in, sars-cov-2"
41202,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.097560976,"the, to, a, in"
41203,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.097560976,"the, protein, in, a"
41204,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.097560976,"the, a, human, viral"
41205,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.097560976,"sars-cov-2, the, with, pangolin-cov"
41206,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.097560976,"the, and, to, that, sars-cov-2, is, of, as"
41207,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.097560976,"sars-cov-2, and, a, that"
41208,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.097560976,"to, the, be, a"
41209,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.097560976,"the, rbd, to, sars-cov-2"
41210,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.097560976,"the, and, spread, to"
41211,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.097560976,"the, for, and, to"
41212,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.097560976,"is, species, of, the"
41213,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.097560976,"a, the, to, host"
41214,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.097560976,"from, a, to, the"
41215,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.097560976,"evidence, that, a, and"
41216,"Those who eagerly peddle suggestions of 

laboratory involvement have consistently failed to present 

credible arguments to support their positions.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.097560976,"who, of, laboratory, to"
41217,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.097560976,"of, the, cases, in"
41218,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.097560976,"to, and, at, the"
41219,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.097560976,"genetic, sequences, from, of"
41220,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.097560976,"of, genetic, that, the"
41221,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.097560976,"similarity, sars-cov-2, to, bat"
41222,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.097560976,"found, in, sars-cov-2, to"
41223,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.097560976,"found, in, coronavirus, nature"
41224,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.097560976,"the, coronaviruses, are, including"
41225,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.097560976,"the, of, not, bats"
41226,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.097560976,"most, of, the, in"
41227,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Bats are the second  

largest order of mammals, with over 1,230 species.",0.097560976,"of, the, with, bats"
41228,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.097560976,"of, and, viruses, the"
41229,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.097560976,"the, as, horseshoe, bats"
41230,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.097560976,"horseshoe, bat, of, sars-cov-2"
41231,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.097560976,"reservoir, of, sars-cov-2, the"
41232,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.097560976,"are, the, coronaviruses, including"
41233,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.097560976,"and, viruses, the, virus"
41234,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.097560976,"virus, the, to, and"
41235,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.097560976,"the, to, for, and"
41236,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.097560976,"viruses, the, in, and"
41237,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.097560976,"and, to, bat, in"
41238,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.097560976,"and, the, of, species"
41239,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.097560976,"of, in, and, to"
41240,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.097560976,"to, in, the, bat"
41241,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.097560976,"with, the, and, is, to, bat, in, of"
41242,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.097560976,"to, the, that, as, a, result, of, into"
41243,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.097560976,"in, a, related, that, the, are, closely, to"
41244,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.097560976,"a, of, sars-cov-2, have"
41245,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.097560976,"have, sars-cov-2, to, with"
41246,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.097560976,"of, sars-cov-2, relatives, with"
41247,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.097560976,"which, closest, with, sars-cov-2,"
41248,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.097560976,"is, at, the, as"
41249,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.097560976,"bat, genome, similarity, sars-cov-2"
41250,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.097560976,"sars-cov-2, are, similar, to"
41251,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.097560976,"sars-cov-2, related, to, the"
41252,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.097560976,"by, closely, related, the"
41253,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.097560976,"the, of, sars-cov-2, viruses"
41254,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.097560976,"to, the, of, by"
41255,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.097560976,"to, the, of, rbd"
41256,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.097560976,"that, have, the, of"
41257,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.097560976,"to, have, the, with"
41258,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","This suggests that the BANAL series may be able to directly infect  

humans.",0.097560976,"to, be, that, may"
41259,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.097560976,"in, the, of, is"
41260,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.097560976,"a, to, the, is"
41261,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.097560976,"bat, virus, strain, of"
41262,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.097560976,"of, the, is, group"
41263,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.097560976,"genomic, sars-cov-2, are, to"
41264,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.097560976,"virus, that, an, animal, to, a, human, zoonotic"
41265,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.097560976,"by, the, of, a, in, to, that, sars, with, or, virus, for"
41266,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.097560976,"a, of, the, by, that, or, to, virus"
41267,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.097560976,"that, a, likely, the, of, and, evidence, to"
41268,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.097560976,"the, and, to, a, of, found, in, human"
41269,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.097560976,"a, of, in, that, for, sars, with, by, the, or, to, virus"
41270,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.097560976,"the, virus, is, to, and, that, in, animal"
41271,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.097560976,"a, known, and, association, in, the, that, to"
41272,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.097560976,"the, is, and, not, an, with, to, of"
41273,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.097560976,"and, natural, of, origin"
41274,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.097560976,"and, to, the, huanan, seafood, market, of, a"
41275,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.097560976,"the, that, in, to, and, a, known, association"
41276,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.097560976,"that, a, was, likely, the, of, sars-cov-2, and"
41277,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.097560976,"from, market, in, that, the, to, of, were"
41278,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.097560976,"the, sars-cov-2, over, to"
41279,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.097560976,"the, cause, is, to"
41280,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.097560976,"the, natural, sars-cov-2, a"
41281,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.097560976,"including, coronaviruses, to, and"
41282,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.097560976,"sars-cov-2, that, and, to"
41283,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.097560976,"that, found, in, sars-cov-2"
41284,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.097560976,"that, bats, sars-cov-2, to"
41285,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.097560976,"the, also, from, as"
41286,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.097560976,"the, in, of, to"
41287,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.097560976,"sars-cov-2, natural, and, a"
41288,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.097560976,"a, in, humans, and"
41289,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.097560976,"was, in, and, a"
41290,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.097560976,"a, origin, sars-cov-2, in"
41291,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.097560976,"a, that, the, virus"
41292,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.097560976,"virus, that, the, bat"
41293,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.097560976,"a, is, that, not"
41294,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.097560976,"ace2, a, sars-cov-2, spike"
41295,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.097560976,"is, virus, that, the"
41296,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.097560976,"from, the, virus, previously"
41297,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","atural  

selection in an animal host before zoonotic  

transfer;",0.097560976,"an, animal, host, in"
41298,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.097560976,"the, reservoir, likely, that"
41299,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.097560976,"its, the, bats, to"
41300,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.097560976,"the, of, given, as"
41301,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.097560976,"the, is, to, human"
41302,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.097560976,"the, from, to, human"
41303,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.097560976,"this, of, the, in"
41304,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.097560976,"we, similar, of, sars-cov-2"
41305,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.097560976,"the, sars-cov-2, a, or"
41306,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.097560976,"that, a, and, not"
41307,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.097560976,"a, the, that, discovered"
41308,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.097560976,"the, of, showed, that"
41309,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.097560976,"a, in, the, nature"
41310,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.097560976,"coronavirus, found, in, nature"
41311,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.097560976,"that, the, sars-, and"
41312,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.097560976,"the, sars-, to, that"
41313,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.097560976,"the, to, that, from"
41314,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",The COVID-19 most likely developed from bat origin coronaviruses,0.097560976,"from, likely, coronaviruses, bat"
41315,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.097560976,"of, the, re-, that"
41316,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.097560976,"of, the, that, viruses"
41317,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.097560976,"that, the, viruses, same"
41318,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.097560976,"of, covid-19, to, virus, that, in, and, the"
41319,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.097560976,"bats, in, to, virus"
41320,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.097560976,"of, viruses, are, a"
41321,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.097560976,"to, the, in, be"
41322,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.097560976,"the, been, in, of"
41323,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.097560976,"the, was, in, of"
41324,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.097560976,"the, most, of, in"
41325,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.097560976,"of, which, was, in"
41326,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.097560976,"that, bat, to, it"
41327,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.097560976,"and, in, to, that, the, of, coronavirus, bats"
41328,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.097560976,"in, the, with, that"
41329,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.097560976,"to, contact, would, the"
41330,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.097560976,"in, the, with, not"
41331,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.097560976,"that, has, to, with"
41332,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.097560976,"the, known, in, of"
41333,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.097560976,"the, as, a, of"
41334,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.097560976,"a, of, the, revealed"
41335,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.097560976,"have, in, of, as"
41336,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.097560976,"of, the, in, these"
41337,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.097560976,"the, of, species, is"
41338,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.097560976,"one, that, the, of"
41339,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.097560976,"is, in, the, bat"
41340,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.097560976,"and, from, the, humans"
41341,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.097560976,"the, to, would, contact"
41342,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.097560976,"the, from, is, and"
41343,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.097560976,"would, be, the, from"
41344,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.097560976,"the, closely, related, by"
41345,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.097560976,"virus, in, bats, to"
41346,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.097560976,"the, of, and, between"
41347,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.097560976,"by, in, their, the"
41348,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.097560976,"the, and, bats, may"
41349,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.097560976,"the, and, an, intermediate"
41350,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.097560976,"the, of, this, is"
41351,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.097560976,"the, likely, to, animals"
41352,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.097560976,"a, from, the, which"
41353,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.097560976,"a, with, genome, that"
41354,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.097560976,"a, sars-cov-2, with, cov"
41355,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.097560976,"many, other, and, is"
41356,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.097560976,"the, of, and, zoonotic"
41357,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.097560976,"of, to, the, virus"
41358,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.097560976,"on, of, likely, origin"
41359,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.097560976,"a, of, that, by, the, or, to, virus"
41360,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.097560976,"the, not, in, with"
41361,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.097560976,"that, host, not, a"
41362,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.097560976,"that, it, to, bat"
41363,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.097560976,"that, sars-cov-2, through, a"
41364,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.097560976,"is, of, an, the"
41365,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.097560976,"that, the, with, or"
41366,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.097560976,"sars-cov-2, in, to, species,"
41367,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.097560976,"that, sars-cov-2, as, to"
41368,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.097560976,"he, the, of, sars-cov-2"
41369,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.097560976,"that, sars-cov-2, the, reservoir"
41370,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.097560976,"the, reservoir, of, sars-cov-2"
41371,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.097560976,"other, and, been, the"
41372,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.097560976,"that, a, was, the, of, sars-cov-2, and, to"
41373,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.097560976,"from, was, the, as"
41374,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.097560976,"the, more, likely, cov"
41375,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.097560976,"to, the, genome, be"
41376,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.097560976,"the, that, likely, virus"
41377,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.097560976,"a, the, human, and"
41378,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.097560976,"has, natural, and, the"
41379,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.097560976,"and, the, has, of"
41380,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.097560976,"a, the, human, viral"
41381,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.097560976,"given, the, of, as"
41382,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.097560976,"by, in, the, their"
41383,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.097560976,"and, are, sars-cov-2, ratg13"
41384,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.097560976,"of, that, sars-cov-2, and, are, in, which, both"
41385,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.097560976,"in, and, to, that, sars-cov-2, of, ratg13, are"
41386,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.097560976,"bat, similarity, sars-cov-2, genome"
41387,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.097560976,"that, the, cannot, be"
41388,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.097560976,"be, the, that, from"
41389,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.097560976,"the, ratg13, from, has"
41390,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.097560976,"from, that, is, this"
41391,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.097560976,"bat, of, sars-cov-2, from"
41392,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.097560976,"and, sars-cov, of, bat"
41393,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.097560976,"from, of, sars-cov-2, and"
41394,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.097560976,"of, similar, sars-cov-2, we"
41395,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.097560976,"of, and, sars-cov-2, sequences"
41396,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.097560976,"ratg13, bat, closest, of"
41397,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.097560976,"the, of, in, was"
41398,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.097560976,"these, of, in, the"
41399,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.097560976,"of, the, to, which"
41400,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.097560976,"these, are, to, the, in, and, that, be"
41401,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.097560976,"the, that, its, bats"
41402,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.097560976,"the, that, sars-cov-2, bats"
41403,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.097560976,"all, that, the, a"
41404,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.097560976,"that, sars-cov-2, and, for"
41405,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.097560976,"that, the, virus, likely"
41406,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.097560976,"that, hosts, for, are"
41407,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.097560976,"also, that, the, than"
41408,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.097560976,"in, the, that, of, were, to, from, market"
41409,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.097560976,"the, that, for, a"
41410,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.097560976,"that, to, sars-cov-2, bats"
41411,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.097560976,"that, as, to, sars-cov-2"
41412,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.097560976,"a, bat, sars-cov-2, the"
41413,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.097560976,"sars-cov-2, a, origin, in"
41414,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.097560976,"the, sars-cov-2, a, bat"
41415,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.097560976,"to, sequence, a, from"
41416,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.097560976,"from, genome, to, of"
41417,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.097560976,"found, of, to, in"
41418,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.097560976,"of, in, which, was"
41419,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.097560976,"pangolin, to, of, and"
41420,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.097560976,"similar, to, and, in"
41421,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.097560976,"in, study, that, are"
41422,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.097560976,"that, in, for, sars-cov-2"
41423,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.097560976,"that, are, hosts, for"
41424,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.097560976,"in, be, that, an"
41425,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.097560976,"a, coronavirus, the, of, and, in, that, receptor"
41426,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.097560976,"the, have, sars-cov-2, to"
41427,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.097560976,"sequences, of, sars-cov-2, and"
41428,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.097560976,"sars-cov-2, the, of, that"
41429,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.097560976,"in, the, and, are, to, viruses, for, be"
41430,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.097560976,"the, to, be, in"
41431,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.097560976,"that, are, the, to, these, be, in, and"
41432,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.097560976,"that, the, are, bat"
41433,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.097560976,"we, believe, the, than"
41434,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.097560976,"the, that, bat, for"
41435,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.097560976,"that, has, of, sars-cov-2"
41436,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.097560976,"in, the, with, to"
41437,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.097560976,"sars-cov-2, to, cov, the"
41438,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.097560976,"bat, to, in, the"
41439,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.097560976,"have, the, with, to"
41440,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.097560976,"sars-cov-2, is, and, bat, as, to, that, in"
41441,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.097560976,"as, and, the, of, to, that, sars-cov-2, is"
41442,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.097560976,"in, are, to, that, of, sars-cov-2, and, ratg13"
41443,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.097560976,"bat, cov, the, origin"
41444,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.097560976,"in, this, that, the"
41445,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.097560976,"and, the, which, is"
41446,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.097560976,"that, the, covs,, and"
41447,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.097560976,"with, the, that, or"
41448,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.097560976,"sars-cov-2, the, viruses, and"
41449,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.097560976,"the, that, viruses, same"
41450,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.097560976,"the, also, that, than"
41451,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.097560976,"sars-cov-2, are, ratg13, and"
41452,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.097560976,"the, bat, origin, cov"
41453,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.097560976,"in, sars-cov-2, that, may"
41454,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.097560976,"the, from, previously, virus"
41455,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.097560976,"other, a, that, sars-cov-2"
41456,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.097560976,"genome, results, bat, of"
41457,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.097560976,"of, the, with, bat"
41458,"In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.097560976,"to, with, more, than"
41459,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.097560976,"the, bat, show, with"
41460,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.097560976,"the, cov, more, likely"
41461,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.097560976,"to, that, has, with"
41462,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.097560976,"that, pangolin-cov, with, to"
41463,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.097560976,"sars-cov-2, the, but, of"
41464,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.097560976,"pangolin-cov, with, the, of"
41465,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.097560976,"of, bat-sl-cov-2, pangolin-cov, with"
41466,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.097560976,"revealed, and, the, from"
41467,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.097560976,"sars-cov-2, that, the, for"
41468,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.097560976,"in, from, and, the"
41469,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.097560976,"the, in, and, a"
41470,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.097560976,"cov, and, a, the"
41471,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.097560976,"and, the, of, are, a, bats, that, for"
41472,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.097560976,"that, the, and, covs,"
41473,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.097560976,"the, pangolin-cov, is, sars-cov-2"
41474,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.097560976,"sars-cov-2, and, the, in"
41475,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.097560976,"sars-cov-2, the, and, in"
41476,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.097560976,"the, of, virus, hace2."
41477,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.097560976,"of, virus, at, the"
41478,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.097560976,"that, be, in, an"
41479,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.097560976,"this, the, in, that"
41480,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.097560976,"not, that, the, was"
41481,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.097560976,"of, the, was, from"
41482,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.097560976,"the, that, of, not"
41483,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.097560976,"bats, the, of, not"
41484,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.097560976,"the, from, that, to"
41485,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.097560976,"was, the, sars-cov-2,, identity"
41486,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.097560976,"is, the, pangolin-cov, sars-cov-2"
41487,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.097560976,"the, for, sars-cov-2, this"
41488,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.097560976,"the, that, cannot, be"
41489,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.097560976,"of, with, bat-sl-cov-2, pangolin-cov"
41490,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.097560976,"a, virus, of, with"
41491,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.097560976,"the, to, by, of"
41492,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.097560976,"the, virus, of, hace2."
41493,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.097560976,"the, was, bat, that"
41494,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.097560976,"bat, the, that, for"
41495,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.097560976,"that, the, as, sars-cov-2."
41496,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.097560976,"the, of, animal, suggested"
41497,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.097560976,"the, sars-cov-2, of, be"
41498,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.097560976,"an, intermediate, and, the"
41499,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.097560976,"the, a, and, sars-cov-2"
41500,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.097560976,"sars-cov-2, the, virus, be"
41501,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.097560976,"be, a, the, sars-cov-2"
41502,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.097560976,"study, the, suggesting, an"
41503,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.097560976,"virus, has, been, of"
41504,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.097560976,"is, at, the, in"
41505,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.097560976,"the, animal, sars-cov-2, be"
41506,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.097560976,"that, the, human, from"
41507,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.097560976,"the, human, a, laboratory"
41508,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.097560976,"from, would, be, the"
41509,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.097560976,"the, is, of, to, and, with, not, an"
41510,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.097560976,"of, sars-cov-2, a, bat"
41511,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.097560976,"the, and, for, a"
41512,"Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.097560976,"recently, to, a, sars-cov-2"
41513,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.097560976,"infected, with, sars-cov-2, of"
41514,"This suggests that the BANAL series may be able to directly infect  

humans.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.097560976,"that, may, be, to"
41515,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.097560976,"the, was, has, with"
41516,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.097560976,"closest, sars-cov-2,, which, with"
41517,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.097560976,"the, identity, sars-cov-2,, was"
41518,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.097560976,"that, the, gene, of"
41519,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.097560976,"to, the, coronavirus, in, bats, of, and, that"
41520,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.097560976,"of, closest, bat, ratg13"
41521,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.097560976,"that, one, of, the"
41522,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.097560976,"that, to, pangolin-cov, with"
41523,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.097560976,"the, of, with, pangolin-cov"
41524,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.097560976,"the, that, as, sars-cov-2."
41525,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.097560976,"study, suggesting, the, an"
41526,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.097560976,"to, amino, acid, the"
41527,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.097560976,"the, to, closely, related"
41528,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.097560976,"the, a, sars-cov-2, or"
41529,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.097402597,"the, from, most, and, were, in, of, had, a, which, to, positive, at, one, virus"
41530,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.097402597,"in, a, of, one, to, the, from, which, positive, most, and, had, at, were, virus"
41531,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.097345133,"the, are, in, a, of, viruses, that, progenitor, were, by, and"
41532,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.097345133,"the, of, as, an, when, a, at, that, humans, to, human"
41533,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.097345133,"to, the, bats, as, for, be, and, of, analysis, or, found"
41534,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.097345133,"the, of, a, viruses, in, to, that, and, however,, similar, coronaviruses"
41535,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.097345133,"in, may, from, that, as, to, species, a, coronavirus, is, and"
41536,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.097345133,"in, into, different, all, with, guangdong, this, that, the, sars, than"
41537,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.097345133,"is, a, and, from, species, as, to, that, may, coronavirus, in"
41538,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.097345133,"similar, to, the, coronavirus, in, of, and, that, animals, a, city"
41539,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.097345133,"that, to, human, as, at, when, the, an, humans, a, of"
41540,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.097345133,"analysis, bats, as, the, found, to, be, or, of, for, and"
41541,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.097345133,"the, of, and, coronaviruses, that, a, in, however,, viruses, similar, to"
41542,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.097345133,"a, by, in, china, that, the, virus, to, of, were, bats"
41543,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.097345133,"a, by, from, was, at, in, that, the, virus, to, of"
41544,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.097345133,"a, of, the, by, that, and, are, in, progenitor, viruses, were"
41545,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.097345133,"in, with, the, by, and, to, that, is, of, are, as"
41546,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.097345133,"and, in, were, to, that, the, of, is, bats, are, likely"
41547,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.097345133,"in, the, animals, city, of, that, similar, to, a, coronavirus, and"
41548,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.097345133,"by, the, of, a, in, to, that, bats, were, virus, china"
41549,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.097345133,"from, the, was, to, a, virus, that, by, in, of, at"
41550,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.097345133,"this, that, sars, the, into, than, with, in, different, guangdong, all"
41551,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.097345133,"the, are, to, in, of, as, with, is, that, by, and"
41552,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.097345133,"the, are, to, in, of, is, likely, that, bats, were, and"
41553,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.097222222,"the, of, virus, from, humans, human, and"
41554,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.097222222,"origin, of, the, that, sars-cov-2, and, humans"
41555,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.097222222,"and, to, be, that, the, of, sars-cov-2"
41556,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.097222222,"as, the, have, and, reservoirs, viruses, other"
41557,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.097222222,"of, the, and, are, other, as, viruses"
41558,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.097222222,"a, and, the, to, from, animals, humans,"
41559,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.097222222,"the, of, is, in, found, to, through"
41560,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.097222222,"the, be, of, sars-cov-2, in, this, from"
41561,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.097222222,"that, the, was, not, a, by, other"
41562,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.097222222,"are, and, a, several, to, in, as"
41563,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.097222222,"the, origin, of, that, humans, and, sars-cov-2"
41564,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.097222222,"a, that, the, sars-cov-2, and, which, by"
41565,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.097222222,"this, in, the, of, which, that, sars-cov-2"
41566,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.097222222,"sars-cov-2, of, the, and, with, in, potential"
41567,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.097222222,"in, the, to, viruses, because, other, more"
41568,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.097222222,"the, of, that, in, a, multiple, to"
41569,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.097222222,"a, from, in, that, the, to, of"
41570,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.097222222,"the, also, a, in, to, that, of"
41571,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.097222222,"that, from, to, an, is, in, sars-cov-2"
41572,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.097222222,"because, viruses, in, more, to, the, other"
41573,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.097222222,"the, as, confirmed, at, that, infected, were"
41574,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.097222222,"a, wet, market, in, that, the, to"
41575,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.097222222,"the, to, was, in, from, of, a"
41576,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.097222222,"were, found, to, that, are, for, this"
41577,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.097222222,"of, to, a, was, from, found, in"
41578,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.097222222,"the, and, that, a, but, does, not"
41579,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.097222222,"to, the, of, and, that, a, outbreak"
41580,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.097222222,"not, a, that, the, was, by, other"
41581,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.097222222,"evidence, that, the, of, all, have, for"
41582,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.097222222,"of, covid-19, with, a, to, and, the"
41583,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.097222222,"of, the, and, to, in, virus, genetic"
41584,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.097222222,"the, is, that, in, to, and, had"
41585,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.097222222,"study, of, is, a, shares, with, the"
41586,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.097222222,"in, the, of, with, pneumonia, patients, seafood"
41587,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.097222222,"a, the, by, that, sars-cov-2, and, which"
41588,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.097222222,"the, by, and, to, that, sars-cov-2, is"
41589,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.097222222,"the, as, of, mers-cov, that, bat, and"
41590,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.097222222,"isolated, from, showed, and, with, in, the"
41591,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.097222222,"of, and, related, to, that, such, as"
41592,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.097222222,"in, and, sars-cov-2, with, bat, the, between"
41593,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.097222222,"the, of, that, s, a, sequence, in"
41594,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.097222222,"a, from, in, that, the, of, were"
41595,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.097222222,"sequence, in, the, s, of, a, that"
41596,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.097222222,"the, patients, with, pneumonia, in, seafood, of"
41597,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.097222222,"at, the, and, in, found, most, similar"
41598,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.097222222,"in, a, of, to, the, was, from"
41599,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.097222222,"the, was, of, sars-cov-2, in, from, a"
41600,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.097222222,"of, the, this, that, sars-cov-2, in, which"
41601,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.097222222,"to, are, that, this, were, for, found"
41602,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.097222222,"that, an, sars-cov-2, to, from, is, in"
41603,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.097222222,"a, study, the, of, is, shares, with"
41604,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.097222222,"the, that, with, of, sars-cov-2, is, an"
41605,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.097222222,"in, the, and, found, similar, most, at"
41606,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.097222222,"that, and, be, sars-cov-2, to, the, rbd"
41607,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.097222222,"and, the, rbd, to, be, that, sars-cov-2"
41608,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.097222222,"the, of, and, that, a, evidence, to"
41609,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.097222222,"in, of, to, the, covid-19, were, market"
41610,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.097222222,"and, a, of, sars-cov-2, in, the, to"
41611,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.097222222,"the, of, and, species, in, likely, or"
41612,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.097222222,"the, have, as, reservoirs, and, viruses, other"
41613,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.097222222,"the, related, is, by, similar, to, genetic"
41614,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.097222222,"the, to, through, in, of, is, found"
41615,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.097222222,"related, to, by, genetic, is, similar, the"
41616,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.097222222,"the, other, genomic, in, and, than, a"
41617,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.097222222,"the, that, identified, by, researchers, between, and"
41618,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.097222222,"a, of, were, found, with, suggesting, that"
41619,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.097222222,"the, that, in, a, to, wet, market"
41620,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.097222222,"animal, a, in, the, that, to, sars"
41621,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.097222222,"the, likely, or, species, of, in, and"
41622,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.097222222,"of, to, a, sequence, from, found, in"
41623,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.097222222,"human, and, from, of, the, virus, humans"
41624,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.097222222,"the, that, infected, were, at, as, confirmed"
41625,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.097222222,"the, of, from, identical, a, and, more"
41626,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.097222222,"the, is, to, and, that, had, in"
41627,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.097222222,"the, covid-19, a, of, to, with, and"
41628,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.097222222,"direct, to, other, with, of, and, in"
41629,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.097222222,"a, in, that, animal, sars, the, to"
41630,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.097222222,"are, of, many, and, that, in, human"
41631,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.097222222,"the, sars-cov-2, from, in, of, this, be"
41632,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.097222222,"the, sars-cov-2, was, in, from, of, a"
41633,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.097222222,"from, in, to, sars-cov-2,, that, the, is"
41634,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.097222222,"in, shows, that, the, is, to, of"
41635,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.097222222,"the, of, a, from, identical, and, more"
41636,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.097222222,"in, and, all, sars-cov-2, that, the, is"
41637,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.097222222,"a, the, and, that, does, not, but"
41638,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.097222222,"and, to, was, not, the, that, a"
41639,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.097222222,"that, a, the, of, outbreak, and, to"
41640,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.097222222,"have, for, the, of, evidence, all, that"
41641,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.097222222,"of, with, to, other, and, in, direct"
41642,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.097222222,"the, in, and, was, masked, palm, civet"
41643,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.097222222,"to, of, bats, and, as, are, more"
41644,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.097222222,"and, was, in, the, masked, palm, civet"
41645,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.097222222,"from, intermediate, and, the, may, have, in"
41646,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.097222222,"the, a, humans,, from, animals, to, and"
41647,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.097222222,"bat, that, the, of, as, and, mers-cov"
41648,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.097222222,"the, isolated, from, in, with, and, showed"
41649,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.097222222,"to, the, has, from, and, scenario, be"
41650,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.097222222,"in, a, sars-cov-2, to, be, with, coronavirus"
41651,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.097222222,"the, to, and, that, was, a, not"
41652,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.097222222,"intermediate, and, may, have, the, from, in"
41653,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.097222222,"that, of, an, is, with, sars-cov-2, the"
41654,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.097222222,"the, well, hypothesis, of, natural, origin, and"
41655,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.097222222,"by, researchers, the, that, identified, between, and"
41656,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.097222222,"from, and, has, to, be, the, scenario"
41657,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.097222222,"the, hypothesis, of, natural, origin, well, and"
41658,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.097222222,"from, and, to, the, that, sars-cov-2, a"
41659,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.097222222,"from, in, the, of, that, a, to"
41660,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.097222222,"in, the, of, a, from, that, were"
41661,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.097222222,"to, in, the, shows, that, is, of"
41662,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.097222222,"in, a, of, to, was, from, found"
41663,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.097222222,"of, from, a, sequence, found, in, to"
41664,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.097222222,"to, sars-cov-2, a, of, in, the, and"
41665,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.097222222,"a, other, genomic, in, than, the, and"
41666,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.097222222,"are, the, as, of, and, viruses, other"
41667,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.097222222,"and, bat, cov, pangolin, cov), the, viruses"
41668,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.097222222,"between, sars-cov-2, and, with, the, bat, in"
41669,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.097222222,"all, sars-cov-2, the, and, in, that, is"
41670,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.097222222,"that, the, sars-cov-2, and, to, is, by"
41671,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.097222222,"to, bats, of, and, are, more, as"
41672,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.097222222,"a, of, found, that, were, with, suggesting"
41673,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.097222222,"coronavirus, a, with, sars-cov-2, to, be, in"
41674,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.097222222,"to, a, are, as, several, and, in"
41675,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.097222222,"of, that, to, such, as, and, related"
41676,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.097222222,"that, many, of, human, are, and, in"
41677,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.097222222,"natural, of, in, a, to, that, such"
41678,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.097222222,"natural, of, a, to, that, in, such"
41679,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.097222222,"from, is, to, sars-cov-2,, in, the, that"
41680,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.097222222,"in, also, the, of, that, a, to"
41681,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.097222222,"the, of, potential, with, and, sars-cov-2, in"
41682,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.097222222,"in, to, of, the, virus, genetic, and"
41683,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.097087379,"the, bats, as, reservoirs, zoonotic, they, known, and, of, have"
41684,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.097087379,"the, that, in, of, before, were, by, and, a, early"
41685,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.097087379,"the, of, coronavirus, that, was, to, and, more, related, sars"
41686,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.097087379,"a, by, was, at, seafood, market, the, to, of, were"
41687,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.097087379,"the, that, for, also, was, to, by, a, is, and"
41688,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.097087379,"in, of, the, from, different, strains, and, whole, genome, virus"
41689,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.097087379,"the, that, was, to, more, related, sars, coronavirus, of, and"
41690,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.097087379,"the, in, a, for, of, as, with, that, animal, and"
41691,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.097087379,"the, to, in, for, based, with, on, that, and, other"
41692,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.097087379,"a, was, that, the, also, and, for, to, is, by"
41693,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.097087379,"bats, the, they, have, known, as, reservoirs, of, and, zoonotic"
41694,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.097087379,"whole, genome, of, strains, the, virus, from, in, different, and"
41695,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.097087379,"virus, isolated, from, in, similar, at, with, the, of, receptor"
41696,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.097087379,"viruses, the, in, bats, of, and, that, animals, a, china"
41697,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.097087379,"in, a, of, animal, and, that, the, with, as, for"
41698,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.097087379,"that, and, for, to, other, based, on, the, in, with"
41699,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.097087379,"a, of, the, by, that, early, and, in, were, before"
41700,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.097087379,"that, bats, in, the, china, a, animals, and, of, viruses"
41701,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.097087379,"from, the, virus, similar, with, receptor, in, of, isolated, at"
41702,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.097087379,"a, the, seafood, at, was, market, of, were, to, by"
41703,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.097014925,"the, for, to, a, virus, that, ace2, and, human, would, in, of, an"
41704,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.097014925,"at, an, had, to, a, the, or, by, cases,, exposure, were, of, and"
41705,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.097014925,"of, for, to, human, ace2, a, virus, would, that, in, an, and, the"
41706,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.097014925,"an, a, the, at, and, of, were, to, cases,, by, or, had, exposure"
41707,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.096774194,"in, of, horseshoe"
41708,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.096774194,"a, group, of, the, that, bats"
41709,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.096774194,"viruses, in, a, human, and, to"
41710,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.096774194,"a, animal, in"
41711,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.096774194,"species, in, of"
41712,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.096774194,"in, the, horseshoe"
41713,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.096774194,"the, in, viruses"
41714,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.096774194,"or, with, of, bats,, and, bats"
41715,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.096774194,"to, coronaviruses, bat"
41716,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.096774194,"similar, to, coronaviruses"
41717,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.096774194,"in, similar, to"
41718,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.096774194,"to, have, in"
41719,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.096774194,"have, to, sars-cov-2."
41720,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.096774194,"of, which, sars-cov-2"
41721,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.096774194,"sars-cov-2, emerged, of"
41722,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.096774194,"were, by, bats"
41723,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.096774194,"the, sars-, and"
41724,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.096774194,"in, to, virus"
41725,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.096774194,"sars-cov-2, the, of, used, to, it"
41726,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.096774194,"of, the, it, used, to, sars-cov-2"
41727,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.096774194,"it, that, the, have, used, of"
41728,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.096774194,"it, that, sars-cov-2, the, of, from"
41729,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.096774194,"have, which, is"
41730,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.096774194,"to, that, the, of, and, have, for, origin, sars-cov-2"
41731,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.096774194,"in, is, the, be, and, sars-cov-2"
41732,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.096774194,"sars-cov-2, is, a, found, to, the"
41733,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.096774194,"some, found, sars-cov-2, and, of, coronaviruses"
41734,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.096774194,"the, without, those, and, a, of"
41735,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.096774194,"a, of, the, are, other, to"
41736,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.096774194,"sars-cov-2, and, other"
41737,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.096774194,"as, the, with, that, to, host"
41738,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.096774194,"of, bat, and"
41739,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.096774194,"virus, and, origin"
41740,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.096774194,"a, natural, and"
41741,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.096774194,"a, natural, of"
41742,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.096774194,"and, with, sars-cov-2, to, in, the"
41743,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.096774194,"of, sars-cov-2, genomic"
41744,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.096774194,"sars-cov-2, of, animal, and, that, the"
41745,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.096774194,"the, been, as, of, most, and"
41746,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.096774194,"that, to, with, as, the, host"
41747,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.096774194,"of, the, are, as, in, a"
41748,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.096774194,"bats, are, the, host, for, of"
41749,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.096774194,"their, that, the, of, a, coronavirus"
41750,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.096774194,"the, of, a, ability, as, and"
41751,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.096774194,"had, a, to, and, the, in"
41752,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.096774194,"the, of, were, intermediate, in, as"
41753,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.096774194,"to, sars-cov-2, from, of, bats, the"
41754,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.096774194,"the, has, been, as, of, and"
41755,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.096774194,"the, of, to, it, that, is"
41756,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.096774194,"to, the, in, of, that, covid-19"
41757,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.096774194,"animal, coronavirus, the"
41758,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.096774194,"the, of, and, that, gene, are"
41759,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.096774194,"the, and, has, that, are, of"
41760,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.096774194,"the, and, sars-"
41761,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.096774194,"the, bats, hosts"
41762,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.096774194,"the, natural, and"
41763,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.096774194,"the, that, from, to, as, and"
41764,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.096774194,"that, the, species, as, can, to"
41765,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.096774194,"sars-cov-2, through, of"
41766,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.096774194,"from, to, is, in, over, the"
41767,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",Bats are likely reservoir hosts for SARS-CoV-2,0.096774194,"likely, are, bats"
41768,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.096774194,"the, bats,, to"
41769,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.096774194,"sars-cov-2, to, zoonotic"
41770,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.096774194,"sequence, homology, with"
41771,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.096774194,"sars-cov-2, to, with"
41772,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.096774194,"and, into, the"
41773,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.096774194,"coronaviruses, of, including"
41774,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.096774194,"to, the, bats,"
41775,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.096774194,"the, and, animals"
41776,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.096774194,"the, other, to"
41777,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.096774194,"the, outbreak, animals"
41778,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.096774194,"sars-cov-2, in, the"
41779,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.096774194,"are, the, that"
41780,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.096774194,"the, of, showed"
41781,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","civet cats and raccoon dogs  

are the intermediate hosts",0.096774194,"the, intermediate, and"
41782,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.096774194,"with, the, a, for, from, and"
41783,"Scientific reports published so far include  

hosts, such as bats (28), pangolins (29), cats  

(11), and dogs (30)","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.096774194,"bats, and, dogs"
41784,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.096774194,"can, be, to"
41785,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","with the first case being linked to  

a seafood market",0.096774194,"the, market, with"
41786,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","with the first case being linked to  

a seafood market",0.096774194,"the, a, with"
41787,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.096774194,"the, of, to, be, sars-cov-2, is"
41788,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.096774194,"to, the, been, in, bats, of"
41789,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.096774194,"found, in, bats, to, of, sars-cov-2"
41790,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.096774194,"a, and, the"
41791,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.096774194,"a, and, in"
41792,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.096774194,"the, determining, and, that, a, in"
41793,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.096774194,"and, by, the, that, in, a"
41794,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.096774194,"through, that, and, to, people, at"
41795,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.096774194,"contact, and, that, sars-cov-2, to, through"
41796,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.096774194,"are, the, natural"
41797,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.096774194,"the, of, and, bat, that, ratg13"
41798,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.096774194,"from, bat, not, of, and, they"
41799,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.096774194,"not, of, have, and, the, from"
41800,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.096774194,"that, sars-cov-2, spillover"
41801,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.096774194,"the, that, was"
41802,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.096774194,"sars-cov-2, zoonotic, from"
41803,"According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.096774194,"to, closer, bat"
41804,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.096774194,"the, of, mutations, that, this, a"
41805,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.096774194,"that, were, from, the, and, this"
41806,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.096774194,"are, zoonotic, viruses, the, that, and"
41807,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.096774194,"sars-cov-2, from, zoonotic"
41808,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.096774194,"of, the, that, and, huanan, known"
41809,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.096774194,"the, transmission, and"
41810,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.096774194,"that, of, with, and, the, sars-cov-2"
41811,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.096774194,"a, the, that, cases, huanan, earliest"
41812,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.096774194,"and, a, in"
41813,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.096774194,"in, a, and"
41814,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.096774194,"a, and, an"
41815,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.096774194,"of, from, to, humans, in, sars-cov-2"
41816,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.096774194,"at, to, from, farms, in, were, zoonotic, of, and"
41817,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.096774194,"from, at, in, to, of, were"
41818,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.096774194,"the, of, very, to, as, and"
41819,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.096774194,"the, of, in, as, a, to"
41820,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.096774194,"from, a, with, sars-cov-2, other, still"
41821,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.096774194,"evidence, the, of"
41822,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.096774194,"and, those, of, the, without, a"
41823,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.096774194,"in, the, sars-cov-2, from, and, an"
41824,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.096774194,"the, from, a, market, and, of"
41825,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor",0.096774194,"to, sars-cov-2, a"
41826,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.096774194,"in, to, the, sars-cov-2, also, from"
41827,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.096774194,"is, a, natural, that, its, humans, to, the, for"
41828,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.096774194,"in, to, sars-cov-2, from, and, an"
41829,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.096774194,"be, of, the, and, viruses, to, in, virus, genetic"
41830,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.096774194,"sars-cov-2, their, or"
41831,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.096774194,"the, infected, animals, at, that, market."
41832,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.096774194,"as, the, be, at, with, could"
41833,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.096774194,"the, genome, that, a, in, to"
41834,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.096774194,"we, the, was, transmitted, to, a"
41835,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.096774194,"the, virus, for, to, were, in"
41836,"This suggests that the BANAL series may be able to directly infect  

humans.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.096774194,"that, to, humans."
41837,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.096774194,"the, is, that, of, to, and, a, but, an"
41838,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.096774194,"the, market., animals, that, infected, at"
41839,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.096774194,"that, of, samples, the, animals, for"
41840,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.096774194,"the, to, have, that, of, animals"
41841,"Scientific reports published so far include  

hosts, such as bats (28), pangolins (29), cats  

(11), and dogs (30)","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.096774194,"such, as, and"
41842,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.096774194,"from, such, as, and, dogs,, of"
41843,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.096774194,"on, the, and, with, to, virus"
41844,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.096774194,"the, from, this, that, and, were"
41845,"The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.096774194,"the, that, were"
41846,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.096774194,"the, animals, from, that, also, virus, were, is, and"
41847,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.096774194,"zoonotic, origin,, all"
41848,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.096774194,"they, that, of"
41849,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.096774194,"of, in, horseshoe"
41850,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.096774194,"to, human, coronavirus"
41851,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.096774194,"human, to, and"
41852,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.096774194,"is, and, from"
41853,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.096774194,"the, coronavirus, bat"
41854,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.096774194,"a, that, bat"
41855,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.096774194,"animal, to, the"
41856,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.096774194,"the, and, to, a, of, in"
41857,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.096774194,"and, a, to, the, of, with"
41858,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.096774194,"indicates, that, the, of, and, in"
41859,"with the first case being linked to  

a seafood market","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.096774194,"with, the, market"
41860,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.096774194,"the, coronavirus, to"
41861,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.096774194,"the, have, a"
41862,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.096774194,"the, sars-cov-2, from"
41863,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.096774194,"the, bat, coronavirus"
41864,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.096774194,"has, sars-cov-2, the"
41865,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.096774194,"the, virus, has"
41866,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.096774194,"a, and, sars-cov-2, has, to, the"
41867,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.096774194,"and, bat, of"
41868,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.096774194,"the, and, is"
41869,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.096774194,"to, bat, the"
41870,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.096774194,"to, the, and"
41871,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.096774194,"one, of, the"
41872,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.096774194,"the, is, bat"
41873,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.096774194,"to, of, the"
41874,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.096774194,"analysis, based, on, the, of, that"
41875,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.096774194,"of, the, by, that, have, to"
41876,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.096774194,"the, that, of, sars-cov-2, is, an"
41877,"bats are also important reservoir species for a great 

range of coronaviruses","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.096774194,"bats, are, a"
41878,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.096774194,"that, people, through, and, at, to"
41879,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.096774194,"to, that, the, bats, and, have"
41880,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.096774194,"to, the, of, and, which, virus"
41881,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.096774194,"of, virus, to, and, are, the"
41882,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.096774194,"that, has, been"
41883,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.096774194,"covid-19, that, to"
41884,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.096774194,"the, virus, and, in, that, to"
41885,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.096774194,"and, the, natural"
41886,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.096774194,"the, into, and"
41887,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.096774194,"also, the, and"
41888,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.096774194,"sequence, that, of"
41889,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.096774194,"and, their, is, the, for, to"
41890,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.096774194,"the, a, and, of, on, with"
41891,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.096774194,"is, with, the, sequence, of, on"
41892,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.096774194,"from, animals, the"
41893,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.096774194,"the, infected, from"
41894,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.096774194,"the, been, in"
41895,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.096774194,"it, that, emerged"
41896,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.096774194,"the, of, that, have, used, it"
41897,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.096774194,"a, of, that, the, group, bats"
41898,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.096774194,"coronavirus, to, human"
41899,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.096774194,"has, over, to"
41900,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.096774194,"that, and, for, sars-cov-2, to, the"
41901,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.096774194,"to, the, of, for, more, than"
41902,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.096774194,"the, could, be, with, at, as"
41903,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.096774194,"the, of, to, be, for, and"
41904,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.096774194,"the, of, with, and, recombination, or"
41905,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.096774194,"the, was, to, with, involved, of"
41906,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.096774194,"at, the, with, thus, bats, for"
41907,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.096774194,"to, the, bats, be, of, recombination"
41908,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.096774194,"found, with, the, of, to, as"
41909,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.096774194,"closer, to, bat"
41910,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.096774194,"sars-cov, is, bat"
41911,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.096774194,"is, bat, to"
41912,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.096774194,"and, to, human"
41913,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.096774194,"to, humans, spillover"
41914,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.096774194,"cause, in, to"
41915,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.096774194,"bat, cov, the, with, sars-cov-2, that"
41916,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.096774194,"has, the, of"
41917,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.096774194,"that, and, sars-cov-2, to, the, between"
41918,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.096774194,"the, beta, and, to, that, have"
41919,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.096774194,"to, sars-cov-2, spike"
41920,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.096774194,"are, a, as, the, of, in"
41921,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.096774194,"he, pangolin, are"
41922,"bats are also important reservoir species for a great 

range of coronaviruses","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.096774194,"are, a, of"
41923,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.096774194,"isolated, in, as"
41924,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.096774194,"has, the, virus"
41925,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.096774194,"in, which, the"
41926,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.096774194,"animal, is, transmitted"
41927,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.096774194,"the, a, from"
41928,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.096774194,"is, the, for"
41929,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.096774194,"bat, coronaviruses, to"
41930,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.096774194,"cause, to, in"
41931,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.096774194,"is, the, from"
41932,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.096774194,"to, the, sars, bats, in, of, from, coronaviruses, isolated"
41933,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.096774194,"bat, all, in"
41934,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.096774194,"natural, a, and"
41935,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.096774194,"animal, sars-cov-2, and"
41936,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.096774194,"a, has, sars-cov-2"
41937,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.096774194,"sars-cov-2, animal, or"
41938,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.096774194,"sars-cov-2, is, and"
41939,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.096774194,"bats, virus, ecological"
41940,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.096774194,"from, infected, the"
41941,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.096774194,"the, animal, another, species, and, humans"
41942,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.096774194,"that, sars-cov-2, through, contact, and, to"
41943,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.096774194,"that, of, sars-cov-2, is, it, an"
41944,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.096774194,"to, that, of, and, more, sars-cov-2"
41945,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.096774194,"coronavirus, the, to"
41946,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.096774194,"the, of, that, virus, to, and"
41947,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.096774194,"genome, was, the, virus, of, sars-like"
41948,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.096774194,"the, of, covid-19, with, and, in"
41949,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.096774194,"of, the, reservoir"
41950,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.096774194,"be, virus, the"
41951,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.096774194,"the, zoonotic, as"
41952,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.096774194,"the, that, are"
41953,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.096774194,"the, that, and, are, zoonotic, viruses"
41954,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.096774194,"that, and, are"
41955,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.096774194,"that, are, the"
41956,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.096774194,"bats, the, as, reservoirs, of, and"
41957,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.096774194,"the, of, to, with, a, and"
41958,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.096774194,"bat, coronavirus, with"
41959,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.096774194,"with, the, and, of, bat, sars-"
41960,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.096774194,"from, as, that, to, and, the"
41961,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.096774194,"the, as, to, very, of, and"
41962,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.096774194,"of, covid-19, to, and, the, approximately"
41963,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.096774194,"of, origin,, the, and, to, virus"
41964,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","no modifications were  

recorded for nonstructural proteins NSP7, NSP13  

and the structured and accessory proteins p6 and 8b.",0.096774194,"were, the, and"
41965,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","no modifications were  

recorded for nonstructural proteins NSP7, NSP13  

and the structured and accessory proteins p6 and 8b.",0.096774194,"were, for, the"
41966,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","no modifications were  

recorded for nonstructural proteins NSP7, NSP13  

and the structured and accessory proteins p6 and 8b.",0.096774194,"proteins, the, and"
41967,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.096774194,"of, with, in"
41968,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.096774194,"to, sars-cov-2, zoonotic"
41969,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.096774194,"to, in, human"
41970,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.096774194,"host, sars-cov-2, animal"
41971,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.096774194,"that, a, the, humans, studies, in, further, to, live"
41972,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","the close relation  

between SARS coronavirus and 2019-nCoV",0.096774194,"and, the, coronavirus"
41973,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.096774194,"is, transmitted, animal"
41974,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.096774194,"the, is, currently"
41975,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.096774194,"in, a, that"
41976,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.096774194,"bat, that, a"
41977,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.096774194,"a, sars-cov-2, that"
41978,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.096774194,"in, from, a"
41979,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.096774194,"based, on, the, analysis, of, that"
41980,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.096774194,"the, of, were, a, for, from"
41981,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.096774194,"a, of, the, that, and, with"
41982,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.096774194,"and, sars-cov-2, together, with, that, the"
41983,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.096774194,"that, and, are, the, gene, of"
41984,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.096774194,"and, that, the, bat, ratg13, of"
41985,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.096774194,"sars-cov-2, other, and"
41986,"Malayan pangolins (Manis javanica)  

illegally imported into Guangdong province  

contain coronaviruses similar to SARS- 

CoV-22","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.096774194,"pangolins, to, sars-"
41987,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.096774194,"for, the, of, animals, samples, that"
41988,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Bats are natural hosts of many of the known  

coronaviruses",0.096774194,"the, many, of"
41989,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.096774194,"between, bats, and, may, from, in"
41990,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.096774194,"the, of, to, that, host,, this"
41991,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.096774194,"currently, the, is"
41992,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.096774194,"pangolin, to, the"
41993,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.096774194,"the, strain, sars-cov-2"
41994,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.096774194,"that, of, to, is, a, the"
41995,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.096774194,"a, of, the, that, at, in"
41996,"Malayan pangolins (Manis javanica)  

illegally imported into Guangdong province  

contain coronaviruses similar to SARS- 

CoV-22","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.096774194,"similar, to, sars-"
41997,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.096774194,"he, are, pangolin"
41998,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.096774194,"are, coronaviruses, sars-cov-2."
41999,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.096774194,"to, and, sars-cov-2."
42000,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.096774194,"these, a, of"
42001,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.096774194,"that, a, host"
42002,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.096774194,"in, an, of, reported, and, the"
42003,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.096774194,"found, similar, and, on, the, of"
42004,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.096774194,"in, have, to"
42005,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.096774194,"of, the, lineage, sars-cov-2, and, b"
42006,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.096774194,"bats, and, sars-cov-2"
42007,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.096774194,"the, and, to, sars-cov-2, of, cov"
42008,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.096774194,"and, to, the, of, bats, sars-cov-2"
42009,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.096774194,"the, of, to, et, al.,, sars-cov-2"
42010,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.096774194,"the, in, horseshoe"
42011,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.096774194,"an, the, of"
42012,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.096774194,"an, animal, the"
42013,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.096774194,"of, many, and, a, that, in"
42014,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.096774194,"have, in, or"
42015,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.096774194,"the, viruses, in"
42016,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.096774194,"in, has, of"
42017,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.096774194,"has, natural, in"
42018,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.096774194,"a, from, the"
42019,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.096774194,"found, in, the, to, that, ("
42020,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.096774194,"a, to, the, we, was, transmitted"
42021,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.096774194,"the, was, by"
42022,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.096774194,"a, the, animals"
42023,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.096774194,"we, a, was"
42024,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.096774194,"to, was, by, the, a, laboratory"
42025,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.096774194,"all, zoonotic, origin,"
42026,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.096774194,"are, virus, in"
42027,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.096774194,"the, of, human, and, genomic, these"
42028,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.096774194,"virus, ecological, bats"
42029,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K",0.096774194,"to, with, human"
42030,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K",0.096774194,"with, to, in"
42031,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.096774194,"the, and, been"
42032,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.096774194,"in, the, wild"
42033,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.096774194,"and, sars-cov-2, reservoirs, to, in, the"
42034,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.096774194,"the, a, from, and, with, for"
42035,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.096774194,"the, of, a, from, were, for"
42036,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.096774194,"genome, to, a"
42037,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.096774194,"a, sars-cov, mers-cov"
42038,"The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.096774194,"the, were, with"
42039,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.096774194,"pangolins, for, sars-cov-2"
42040,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.096774194,"of, covid-19, had, to, wuhan, the"
42041,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.096774194,"sars-cov-2, of, the, viruses, similar, to"
42042,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.096774194,"the, of, that, host,, to, this"
42043,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.096774194,"a, and, to, of, in, the"
42044,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.096774194,"is, and, to, human, in, been"
42045,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.096774194,"is, the, to, in, from, over"
42046,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.096774194,"the, is, an, with, to, of"
42047,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.096774194,"genome, from, in, the, of, were"
42048,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.096774194,"a, sars-cov-2, coronavirus"
42049,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.096774194,"of, in, has"
42050,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.096774194,"that, the, discovered"
42051,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.096774194,"from, the, virus"
42052,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.096774194,"to, the, market"
42053,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.096774194,"a, the, of, is, that, host"
42054,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.096774194,"in, the, from, an, and, sars-cov-2"
42055,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.096774194,"from, in, also, the, sars-cov-2, to"
42056,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","bats are also important reservoir species for a great 

range of coronaviruses",0.096774194,"are, bats, a"
42057,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","bats are also important reservoir species for a great 

range of coronaviruses",0.096774194,"of, are, a"
42058,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","bats are also important reservoir species for a great 

range of coronaviruses",0.096774194,"a, of, coronaviruses"
42059,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.096774194,"in, the, of, and, an, reported"
42060,"no modifications were  

recorded for nonstructural proteins NSP7, NSP13  

and the structured and accessory proteins p6 and 8b.","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.096774194,"proteins, and, the"
42061,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.096774194,"that, of, sequence"
42062,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.096774194,"be, sars-cov-2, the, amino, in, with"
42063,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.096774194,"the, to, in, ace2, s, protein"
42064,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.096774194,"the, to, sars-cov-2, of, et, al.,"
42065,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.096774194,"the, of, that, and, animal, sars-cov-2"
42066,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.096774194,"the, that, ace2, a, in, animal"
42067,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.096774194,"the, between, sars-cov-2, and, to, that"
42068,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.096774194,"in, the, that, sars-cov-2, to, rbd"
42069,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.096774194,"the, in, sars-cov-2, with, amino, be"
42070,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.096774194,"have, the, and, beta, to, that"
42071,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.096774194,"found, in, the, that, to, ("
42072,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.096774194,"the, in, and, that, a, laboratory"
42073,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.096774194,"the, to, be, of, for, and"
42074,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.096774194,"zoonotic, to, the"
42075,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.096774194,"to, the, intermediate"
42076,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.096774194,"to, an, the"
42077,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.096774194,"from, of, sequences, in, the, that"
42078,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.096774194,"sars-cov-2, coronavirus, to"
42079,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.096774194,"coronavirus, with, bat"
42080,"In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.096774194,"in, to, with"
42081,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan",0.096774194,"of, in, wuhan"
42082,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.096774194,"the, for, from"
42083,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.096774194,"the, of, sequences, in, from, that"
42084,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.096774194,"it, that, a, of, sars-cov-2, the"
42085,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.096774194,"the, in, of, to, that, sars-cov-2"
42086,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.096774194,"a, of, in, bats, the, rhinolophus"
42087,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.096774194,"bats, are, for, the, of, host"
42088,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.096774194,"coronaviruses, are, sars-cov-2."
42089,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.096774194,"sars-cov-2, the, of, that, it, from"
42090,Bats are likely reservoir hosts for SARS-CoV-2,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.096774194,"bats, are, likely"
42091,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.096774194,"the, in, bats, of, and, china"
42092,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.096774194,"the, species, and, humans, another, animal"
42093,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.096774194,"the, reservoirs, and, many, other, have"
42094,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.096774194,"sars-cov-2, of, which"
42095,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.096774194,"in, to, the, virus, were, for"
42096,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.096774194,"in, of, species"
42097,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.096774194,"the, an, of"
42098,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.096774194,"the, an, to"
42099,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.096774194,"in, to, an"
42100,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.096774194,"in, the, and, to, of, bat"
42101,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.096774194,"can, as, that, to, the, species"
42102,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.096774194,"in, a, of, to, that, events"
42103,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.096774194,"are, viruses, to, the, in, and, that, bats, for"
42104,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.096774194,"a, and, to, which, in, the"
42105,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.096774194,"spike, to, sars-cov-2"
42106,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.096774194,"sars-cov-2, of, related"
42107,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.096774194,"are, of, viruses"
42108,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.096774194,"is, that, of, the, natural, reservoir"
42109,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.096774194,"viruses, to, in"
42110,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.096774194,"from, the, is"
42111,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.096774194,"a, the, have"
42112,"S1/S2 cleavage sites of coronaviruses are frequently modi- 

fied by insertions or deletions (indels) during evolution","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.096774194,"s1/s2, cleavage, of"
42113,Genetic evidence suggesting otherwise is yet to be presented.,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.096774194,"genetic, is, to"
42114,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.096774194,"as, in, isolated"
42115,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.096774194,"is, sars-cov-2, the"
42116,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.096774194,"the, is, virus"
42117,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.096774194,"in, the, sars-cov-2"
42118,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.096774194,"these, are, to, the, in, and"
42119,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.096774194,"the, sars-cov-2, and, be, is, in"
42120,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.096774194,"that, were, the"
42121,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.096774194,"zoonotic, the, that"
42122,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.096774194,"the, with, that"
42123,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.096774194,"were, with, the"
42124,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.096774194,"the, huanan, that, known, and, of"
42125,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.096774194,"a, that, the, earliest, cases, huanan"
42126,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.096774194,"the, market, from, and, a, of"
42127,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.096774194,"a, the, on, of, and, with"
42128,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.096774194,"a, of, the, at, by, to"
42129,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.096774194,"studies, that, the, a, live, in, to, humans, further"
42130,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.096774194,"that, were, from, the, and, animals, also, virus, is"
42131,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.096774194,"the, is, only, by, three, from, species, collected, in"
42132,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.096774194,"determining, the, and, a, that, in"
42133,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.096774194,"of, the, in, that, was, later"
42134,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.096774194,"a, that, the, outbreak, of, and"
42135,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.096774194,"the, host, of, and, an, intermediate"
42136,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.096774194,"the, of, sars, in, to, coronaviruses, isolated, from, bats"
42137,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.096774194,"it, that, bats, the, for, as, similar, to, a"
42138,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.096774194,"the, live, from, including, and, in, with, by, of, a, as, to, that, at, virus"
42139,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.096774194,"were, at, zoonotic, of, from, in, and, to, farms"
42140,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.096774194,"the, earliest, and, one, of, suggesting, a, zoonotic, to"
42141,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.096774194,"that, a, the, of, and, is, but, to, an"
42142,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.096774194,"a, the, to, in, had, and"
42143,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.096774194,"and, the, covid-19, approximately, to, of"
42144,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.096774194,"the, wuhan, of, had, to, covid-19"
42145,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.096774194,"to, a, the, earliest, one, suggesting, zoonotic, of, and"
42146,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.096774194,"the, and, a, to, suggesting, of"
42147,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.096774194,"a, to, and, some, are, markets"
42148,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.096774194,"a, some, zoonotic, and, the, to"
42149,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.096774194,"a, at, in, that, the, to"
42150,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.096774194,"of, the, covid-19, in, with, and"
42151,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.096774194,"and, the, but, are, all, with"
42152,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.096774194,"in, a, study, published, the, of"
42153,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.096774194,"study, sars-cov-2, be, a, the, and"
42154,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.096774194,"the, of, were, huanan, market, in"
42155,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.096774194,"the, sars-cov-2, to, a, is, found"
42156,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.096774194,"its, that, to, the, humans, a, is, for, natural"
42157,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.096774194,"bats, and, related, to, that, in"
42158,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.096774194,"in, the, their"
42159,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.096774194,"a, and, reservoirs, to, in, the"
42160,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.096774194,"natural, in, has"
42161,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.096774194,"sars-cov-2, of, through"
42162,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.096774194,"that, it, emerged"
42163,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.096774194,"related, sars-cov-2, of"
42164,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.096774194,"of, is, that"
42165,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.096774194,"a, is, of"
42166,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.096774194,"the, one, of"
42167,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.096774194,"is, the, virus"
42168,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","atural  

selection in an animal host before zoonotic  

transfer;",0.096774194,"an, host, in"
42169,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Malayan pangolins (Manis javanica)  

illegally imported into Guangdong province  

contain coronaviruses similar to SARS- 

CoV-22",0.096774194,"to, sars-, pangolins"
42170,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.096774194,"to, of, is, that, in, including"
42171,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.096774194,"sars-cov-2, a, of, the, it, that"
42172,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.096774194,"the, recombination, or, with, of, and"
42173,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.096774194,"in, is, to, been, human, and"
42174,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.096774194,"a, coronavirus, the, of, that, their"
42175,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.096774194,"the, discovered, that"
42176,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.096774194,"the, genome, bat"
42177,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.096774194,"ace2, in, a, animal, that, the"
42178,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.096774194,"human, and, to, in, a, viruses"
42179,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.096774194,"in, to, that, of, based, on"
42180,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.096774194,"cov, to, than"
42181,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.096774194,"of, the, and, to, in, genetic"
42182,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",The COVID-19 most likely developed from bat origin coronaviruses,0.096774194,"bat, origin, the"
42183,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.096774194,"is, which, have"
42184,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.096774194,"a, of, these"
42185,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.096774194,"is, of, a"
42186,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.096774194,"including, coronaviruses, of"
42187,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.096774194,"viruses, are, of"
42188,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.096774194,"a, are, including"
42189,"In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.096774194,"in, to, viruses"
42190,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.096774194,"were, intermediate, in"
42191,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.096774194,"to, an, in"
42192,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.096774194,"in, the, of, was, that, later"
42193,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.096774194,"and, to, sars-cov-2."
42194,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.096774194,"the, been, to, bats, in, of"
42195,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.096774194,"the, of, bats, in, and, china"
42196,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.096774194,"bats, and, have, the, in, china"
42197,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.096774194,"the, that, to, a, and, coronavirus"
42198,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.096774194,"of, these, to, a, rhinolophus, in"
42199,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.096774194,"indicates, that, the, of, in, and"
42200,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.096774194,"in, china, the, of, between, and"
42201,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.096774194,"in, that, the, virus, were, found"
42202,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.096774194,"in, the, of, were, huanan, market"
42203,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.096774194,"have, to, the, of, animals, that"
42204,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.096774194,"the, was, to, involved, with, of"
42205,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.096774194,"a, of, in, rhinolophus, bats, the"
42206,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.096774194,"the, of, is, natural, reservoir, that"
42207,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.096774194,"that, the, or"
42208,hese close genetic relations suggest that they all have their ecological origin in bat populations,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.096774194,"all, in, bat"
42209,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.096774194,"in, the, from, three, only, collected, species, by, is"
42210,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.096774194,"viruses, the, in, and, bats, or"
42211,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.096774194,"of, bats,, and, bats, with, or"
42212,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.096774194,"and, they, not, from, bat, of"
42213,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.096774194,"markets, are, a, and, some, to"
42214,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.096774194,"of, are, more, to, a, bat"
42215,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.096774194,"and, the, was, of, in, a"
42216,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.096774194,"a, of, was"
42217,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.096774194,"and, was, the, of, in, a"
42218,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.096774194,"the, on, of, is, sequence, with"
42219,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.096774194,"from, the, to, a, live, virus, that, with, as, and, by, in, of, at, including"
42220,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.096774194,"were, bats, by"
42221,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.096774194,"the, in, wild"
42222,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.096774194,"in, their, the"
42223,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.096774194,"of, which, in"
42224,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.096774194,"in, an, of"
42225,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.096774194,"between, and, from, may, in, bats"
42226,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.096774194,"the, have, in, bats, and, china"
42227,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.096774194,"the, animals, a"
42228,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.096774194,"the, of, a, outbreak, that, and"
42229,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.096774194,"and, have, not, from, the, of"
42230,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.096774194,"to, a, from, and, humans,, the"
42231,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.096774194,"a, zoonotic, and, some, the, to"
42232,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.096774194,"the, reservoir, and, not, to, of"
42233,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.096774194,"the, most, been, as, of, and"
42234,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.096774194,"has, been, the, of, as, and"
42235,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.096774194,"other, with, a, still, sars-cov-2, from"
42236,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.096774194,"a, to, has, sars-cov-2, the, and"
42237,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.096774194,"sars-cov-2, to, the, in, reservoirs, and"
42238,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.096774194,"a, in, reservoirs, and, to, the"
42239,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.096774194,"in, the, from, and, a, malayan"
42240,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.096774194,"sars-cov-2, and, identity, pangolin, to, the"
42241,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.096774194,"and, bats, the"
42242,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.096774194,"the, of, virus"
42243,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.096774194,"of, the, virus"
42244,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.096774194,"natural, of, a"
42245,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.096774194,"we, was, a"
42246,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.096774194,"of, a, was"
42247,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.096774194,"are, to, of, the, other, a"
42248,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.096774194,"the, of, have, that, to, by"
42249,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.096774194,"the, by, a, at, to, of"
42250,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","ARS-CoV-2 is a 

natural virus, not a lab-created one.",0.096774194,"is, natural, a"
42251,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","ARS-CoV-2 is a 

natural virus, not a lab-created one.",0.096774194,"natural, is, not"
42252,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.096774194,"the, with, other"
42253,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.096774194,"t, that, sars-cov-2"
42254,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.096774194,"harbor, to, that, in, such, as"
42255,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.096774194,"that, sars-cov-2, a"
42256,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.096774194,"been, sars-cov-2, the"
42257,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.096774194,"the, many, have, and, reservoirs, other"
42258,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.096774194,"the, and, sars-cov"
42259,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.096774194,"the, and, by, a, that, in"
42260,"insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.096774194,"from, of, such, as, dogs,, and"
42261,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.096774194,"the, was, to, by, a, laboratory"
42262,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.096774194,"the, was, in, that, as, for"
42263,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.096774194,"the, not, of"
42264,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","S1/S2 cleavage sites of coronaviruses are frequently modi- 

fied by insertions or deletions (indels) during evolution",0.096774194,"of, cleavage, s1/s2"
42265,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.096774194,"the, an, animal"
42266,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.096774194,"the, more, likely"
42267,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.096774194,"be, the, sars-cov-2"
42268,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.096774194,"the, of, and, that, natural, a"
42269,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",Genetic evidence suggesting otherwise is yet to be presented.,0.096774194,"to, genetic, is"
42270,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.096774194,"the, of, that, sars-cov-2, is, an"
42271,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.096774194,"is, it, that, of, sars-cov-2, an"
42272,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.096774194,"a, as, the, of, and, ability"
42273,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.096774194,"the, is, by, has, such, in"
42274,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.096774194,"natural, of, the, in, to, such"
42275,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.096774194,"sars-cov-2, and, that"
42276,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.096774194,"that, sars-cov-2, from"
42277,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.096774194,"from, that, sars-cov-2"
42278,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.096774194,"viruses, and, to"
42279,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.096774194,"sars-cov-2, was, to"
42280,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.096774194,"that, are, and"
42281,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.096774194,"sars-cov-2, to, bats, in, of, found"
42282,"Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.096774194,"based, on, of, that, to, in"
42283,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.096774194,"of, sequences, to, which, found, in"
42284,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.096774194,"of, sars-cov-2, with"
42285,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.096774194,"most, the, that"
42286,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.096774194,"the, to, other"
42287,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.096774194,"sars-cov-2, be, the"
42288,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.096774194,"such, by, in, the, has, is"
42289,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.096774194,"the, sars-cov-2, be"
42290,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.096774194,"are, that, and"
42291,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.096774194,"sars-cov-2, and, bats"
42292,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.096774194,"analysis, the, for"
42293,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.096774194,"were, at, of, from, in, to"
42294,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.096774194,"of, the, genome, virus, was, sars-like"
42295,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.096774194,"the, of, from, were, in, genome"
42296,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.096774194,"the, that, virus, found, in, were"
42297,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.096774194,"the, of, that, to, a, genome"
42298,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.096774194,"the, a, to, that, bats, as, similar, it, for"
42299,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.096774194,"to, a, of, the, and, that"
42300,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.096774194,"to, in, of, rhinolophus, these, a"
42301,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.096774194,"found, in, which, to, of, sequences"
42302,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.096774194,"to, the, and, their, is, for"
42303,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.096774194,"suggests, for, sars-cov-2"
42304,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.096774194,"are, to, of, the, virus, and"
42305,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.096774194,"a, mutations, that, the, of, this"
42306,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.096774194,"a, that, the, laboratory, and, in"
42307,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.096774194,"the, coronavirus, sars-cov-2,, in, of, than"
42308,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.096774194,"sars-cov-2, been, the"
42309,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.096774194,"the, of, in, and, that, a"
42310,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.096774194,"to, sars-cov-2, bat"
42311,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.096774194,"than, to, cov"
42312,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.096774194,"sars-cov-2, bat, to"
42313,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.096774194,"and, the, to, viruses, are, bats, that, in, for"
42314,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.096774194,"are, to, in, these, the, and"
42315,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.096774194,"or, and, the, in, bats, viruses"
42316,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.096774194,"bats, the, at, with, thus, for"
42317,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same",0.096774194,"the, same, and"
42318,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.096774194,"the, sars-cov-2, together, with, that, and"
42319,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.096774194,"sars-cov-2, and, bat, ratg13, pangolin, the"
42320,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.096774194,"of, the, and, with, bat, sars-"
42321,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.096774194,"the, of, origin"
42322,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.096774194,"that, or, the"
42323,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.096774194,"sars-cov-2, or, their"
42324,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.096774194,"the, are, with, and, all, but"
42325,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.096774194,"have, that, bats"
42326,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.096774194,"in, this, that"
42327,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.096774194,"sars-cov-2, origin, of, for, to, have, that, and, the"
42328,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.096774194,"have, that, the, bats, and, to"
42329,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.096774194,"the, of, more, than, to, for"
42330,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.096774194,"and, more, that, of, sars-cov-2, to"
42331,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.096774194,"the, between, and, of, in, bat"
42332,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.096774194,"the, of, and, in, china, between"
42333,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.096774194,"on, the, of, and, found, similar"
42334,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.096774194,"a, bat, to, of, are, more"
42335,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.096774194,"a, genome, that, the, to, of"
42336,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.096774194,"to, with, sars-cov-2"
42337,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.096774194,"the, sars-cov, and"
42338,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.096774194,"sars-cov-2, and, is"
42339,"�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.096774194,"and, the, same"
42340,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.096774194,"of, the, showed"
42341,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.096774194,"the, and, transmission"
42342,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.096774194,"from, the, for"
42343,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.096774194,"the, analysis, for"
42344,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.096774194,"the, recombination, and"
42345,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.096774194,"of, the, evidence"
42346,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.096774194,"from, a, in"
42347,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.096774194,"from, a, malayan, and, in, the"
42348,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.096774194,"that, have, bats"
42349,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.096774194,"for, the, is"
42350,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.096774194,"and, the, in"
42351,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.096774194,"recombination, the, and"
42352,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.096774194,"the, sars-cov-2, this"
42353,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.096774194,"the, sars-cov-2, pangolin"
42354,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.096774194,"bats, the, recombination, to, be, of"
42355,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.096774194,"as, was, for, the, that, in"
42356,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.096774194,"bat, the, animal"
42357,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.096774194,"that, they, of"
42358,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.096774194,"sars-cov-2, animal, host"
42359,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.096774194,"the, of, an, intermediate, host, and"
42360,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.096774194,"and, be, the"
42361,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.096774194,"the, bat, animal"
42362,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.096774194,"the, a, sars-cov-2"
42363,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.096774194,"the, virus, a"
42364,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.096774194,"be, the, virus"
42365,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.096774194,"and, the, be, sars-cov-2, study, a"
42366,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.096774194,"of, to, an, is, with, the"
42367,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.096774194,"not, of, and, the, to, reservoir"
42368,"ARS-CoV-2 is a 

natural virus, not a lab-created one.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.096774194,"is, natural, not"
42369,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.096774194,"are, a, including"
42370,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.096774194,"that, of, in, events, a, to"
42371,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.096774194,"of, in, a, to, that, events"
42372,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.096774194,"many, in, and, that, a, of"
42373,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.096774194,"that, related, to, in, bats, and"
42374,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.096774194,"that, such, as, to, harbor, in"
42375,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.096774194,"in, the, to, that, sars-cov-2, of"
42376,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.096774194,"such, in, to, the, of, natural"
42377,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.096774194,"the, of, sars-cov-2,, in, coronavirus, than"
42378,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.096774194,"has, that, and, are, the, of"
42379,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.096774194,"the, has, to, that, of, and"
42380,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.096774194,"the, and, of, suggesting, a, to"
42381,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.096774194,"to, in, including, that, is, of"
42382,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.096774194,"sars-cov-2, and, some, of, found, coronaviruses"
42383,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.096774194,"as, the, found, to, with, of"
42384,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.096774194,"in, the, of, and, to, viruses, be, genetic, virus"
42385,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.096774194,"on, the, virus, with, and, to"
42386,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.096774194,"and, the, virus, to, of, origin,"
42387,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.096774194,"the, of, viruses, similar, to, sars-cov-2"
42388,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.096774194,"to, in, the, s, protein, ace2"
42389,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.096774194,"pangolin, and, identity, sars-cov-2, to, the"
42390,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.096774194,"and, sars-cov-2, bat, ratg13, pangolin, the"
42391,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.096491228,"that, palm, in, the, wet, market, a, or, of, transmission, animal"
42392,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.096491228,"only, a, of, also, and, the, to, from, species, different, animals"
42393,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.096491228,"of, these, to, a, genome, from, bat, found, in, yunnan, province"
42394,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.096491228,"a, of, wet, market, in, that, animal, palm, the, transmission, or"
42395,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.096491228,"a, by, at, market, in, that, the, is, to, of, were"
42396,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.096491228,"the, animals, of, from, only, also, to, different, species, a, and"
42397,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.096491228,"the, of, a, to, that, were, in, is, by, at, market"
42398,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.096491228,"in, of, a, to, bat, found, these, genome, from, yunnan, province"
42399,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.096385542,"to, available, sars-cov-2, a, virus, that, and, the"
42400,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.096385542,"the, are, a, of, reservoir, sars-cov-like, viruses, and"
42401,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.096385542,"wuhan, to, the, market, in, of, on, animal"
42402,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.096385542,"were, in, china, wet, market, a, and, animal"
42403,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.096385542,"the, a, to, in, and, animals, at, was"
42404,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.096385542,"the, in, a, one, pathway, that, by, and"
42405,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.096385542,"the, of, and, that, a, in, viruses, are"
42406,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.096385542,"that, of, from, humans, a, in, sars-cov-2, the"
42407,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.096385542,"that, the, sars-cov-2, with, in, hypothesis, of, and"
42408,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.096385542,"the, of, to, a, or, that, evidence, not"
42409,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.096385542,"and, of, to, a, different, they, infect, that"
42410,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.096385542,"sars-cov-2, to, a, virus, available, that, and, the"
42411,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.096385542,"the, of, a, and, wild, sars-cov, palm, civet"
42412,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.096385542,"the, of, patients, were, with, huanan, seafood, market"
42413,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.096385542,"and, at, the, be, or, was, for, of"
42414,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.096385542,"the, of, and, that, nucleotide, sequence, with, as"
42415,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.096385542,"of, the, and, or, sars-, with, as, pangolin"
42416,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.096385542,"a, of, the, that, and, are, in, viruses"
42417,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.096385542,"and, in, to, sars-cov-2,, that, the, of, are"
42418,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.096385542,"in, as, a, that, from, to, and, sequence"
42419,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.096385542,"sars-cov, as, and, the, of, that, sars-cov-2, a"
42420,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.096385542,"an, from, to, the, in, of, a, was"
42421,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.096385542,"a, of, the, from, that, sars-cov-2, in, humans"
42422,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.096385542,"with, to, the, huanan, seafood, market, in, of"
42423,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.096385542,"the, as, species, to, humans, bat, such, and"
42424,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.096385542,"a, that, they, infect, different, of, to, and"
42425,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.096385542,"nucleotide, sequence, with, that, the, of, as, and"
42426,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.096385542,"a, sequence, and, from, as, to, that, in"
42427,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.096385542,"found, in, more, to, that, of, both, and"
42428,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.096385542,"were, a, and, wet, animal, market, in, china"
42429,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.096385542,"are, the, reservoir, of, a, sars-cov-like, and, viruses"
42430,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.096385542,"the, and, pathway, by, a, one, that, in"
42431,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.096385542,"on, the, of, to, animal, market, in, wuhan"
42432,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.096385542,"the, to, was, in, from, an, of, a"
42433,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.096385542,"of, the, in, to, with, huanan, seafood, market"
42434,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.096385542,"the, covid-19, to, and, that, a, but, not"
42435,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.096385542,"the, was, be, at, or, of, for, and"
42436,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.096385542,"that, the, of, to, or, evidence, not, a"
42437,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.096385542,"that, the, sars-cov-2, to, selection, this, of, natural"
42438,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.096385542,"the, that, to, and, a, but, not, covid-19"
42439,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.096385542,"the, huanan, seafood, with, market, of, were, patients"
42440,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.096385542,"in, the, a, was, animals, to, at, and"
42441,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.096385542,"a, the, sars-cov, palm, civet, of, wild, and"
42442,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.096385542,"as, the, to, bat, species, such, and, humans"
42443,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.096385542,"that, the, of, sars-cov-2, and, sars-cov, as, a"
42444,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.096385542,"in, of, found, that, to, both, and, more"
42445,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.096385542,"the, of, with, and, hypothesis, that, sars-cov-2, in"
42446,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.096385542,"the, of, sars-cov-2, to, natural, selection, that, this"
42447,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.096385542,"and, sars-, the, of, with, or, pangolin, as"
42448,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.096385542,"the, and, in, to, that, bat, are, of"
42449,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.096385542,"the, of, and, that, in, are, to, sars-cov-2,"
42450,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.096385542,"in, the, and, to, that, of, bat, are"
42451,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.096296296,"had, a, the, was, an, or, with, cases, of, at, least, patients, to"
42452,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.096296296,"an, a, the, with, at, least, was, of, cases, to, patients, or, had"
42453,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.096153846,"bats, reservoir, of, viruses, in"
42454,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.096153846,"a, that, infect, of, and"
42455,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.096153846,"the, that, in, and, naturally"
42456,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.096153846,"of, the, in, from, a"
42457,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.096153846,"the, that, of, a, body"
42458,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.096153846,"that, the, of, new, a"
42459,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.096153846,"that, bats, or, pangolins, the"
42460,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.096153846,"and, in, many, which, pangolin"
42461,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.096153846,"genetic, in, and, to, a"
42462,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.096153846,"but, a, large, of, are"
42463,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.096153846,"of, animal, species, and, the"
42464,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.096153846,"virus, coronavirus, that, with, and"
42465,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.096153846,"and, revealed, that, virus, of"
42466,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.096153846,"that, with, of, virus, and"
42467,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.096153846,"and, in, to, bat, coronaviruses"
42468,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.096153846,"from, identified, genetic, and, species"
42469,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.096153846,"to, are, identified, genetic, and"
42470,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.096153846,"the, of, to, bat, sars-cov"
42471,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.096153846,"the, to, human, virus, and"
42472,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.096153846,"human, have, which, and, from"
42473,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.096153846,"the, to, infection, which, from"
42474,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.096153846,"the, of, to, possibly, from"
42475,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.096153846,"sars-cov-2, to, with, as, the"
42476,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.096153846,"t, that, sars-cov-2, a, by"
42477,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.096153846,"of, that, sars-cov-2, been, a"
42478,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.096153846,"it, that, of, sars-cov-2, the"
42479,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.096153846,"of, the, that, sars-cov-2, sequences"
42480,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.096153846,"t, that, a, sars-cov-2, by"
42481,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.096153846,"a, from, the, sequence, sars-cov-2"
42482,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.096153846,"the, that, is, by, a"
42483,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.096153846,"virus, that, is, the, was"
42484,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.096153846,"are, a, and, the, to"
42485,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.096153846,"the, of, are, to, a"
42486,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.096153846,"is, sarbecoviruses,, naturally, a, that"
42487,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.096153846,"as, the, to, with, sars-cov-2"
42488,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.096153846,"that, the, with, have, as"
42489,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.096153846,"the, to, that, sars-cov-2, with"
42490,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.096153846,"highly, that, sars-cov-2, the, genome"
42491,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.096153846,"with, to, sars-cov-2, the, genome"
42492,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.096153846,"to, with, sars-cov-2, the, bat"
42493,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.096153846,"to, the, of, sars-cov, bat"
42494,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.096153846,"to, is, of, the, was"
42495,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.096153846,"viruses, the, of, and, a"
42496,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.096153846,"that, the, covid-19, and, sars-cov-2"
42497,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.096153846,"genome, the, bat, virus, and"
42498,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.096153846,"and, pangolin, in, which, many"
42499,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.096153846,"that, and, pangolin, as, intermediate"
42500,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.096153846,"or, of, and, transmission, between"
42501,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.096153846,"sars-cov-2, to, and, in, bat"
42502,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.096153846,"the, of, bat, in, to"
42503,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.096153846,"the, of, case, that, in"
42504,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.096153846,"in, of, the, has, bats"
42505,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.096153846,"the, of, human, a, that"
42506,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.096153846,"of, that, the, a, as"
42507,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.096153846,"the, of, have, as, host"
42508,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.096153846,"to, the, and, virus, human"
42509,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.096153846,"that, the, is, a, thus"
42510,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.096153846,"sars-cov-2, the, of, to, from"
42511,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.096153846,"the, of, as, intermediate, to"
42512,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.096153846,"to, the, bats, hosts, for"
42513,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.096153846,"it, that, the, to, is"
42514,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.096153846,"the, of, later, sars-cov-2, and"
42515,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.096153846,"and, that, of, species, by"
42516,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.096153846,"to, from, and, can, the"
42517,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.096153846,"the, that, natural, and, from"
42518,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.096153846,"the, species, to, that, civets, as, intermediate, and, virus, for"
42519,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.096153846,"to, the, from, transmission, virus"
42520,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.096153846,"early, only, the, of, sars-cov-2"
42521,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.096153846,"the, is, which, was, to"
42522,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.096153846,"the, in, to, from, at"
42523,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.096153846,"from, in, is, at, the"
42524,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.096153846,"sequence, homology, with, the, sars-cov-2"
42525,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.096153846,"other, the, of, and, to"
42526,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.096153846,"coronaviruses, to, the, including, of"
42527,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.096153846,"to, the, in, and, animals"
42528,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.096153846,"the, in, animals, outbreak, china"
42529,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.096153846,"the, that, to, and, with"
42530,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.096153846,"that, sars-cov-2, with, and, to"
42531,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.096153846,"that, sars-cov-2, to, and, is"
42532,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.096153846,"the, with, that, and, to"
42533,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.096153846,"the, that, was, to, are, coronavirus, in, and, at, any"
42534,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.096153846,"a, and, was, in, humans"
42535,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.096153846,"to, the, bats, of, and"
42536,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","with the first case being linked to  

a seafood market",0.096153846,"a, the, case, with, seafood"
42537,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.096153846,"the, sars-cov-2, of, is, to"
42538,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.096153846,"the, found, in, this, evidence"
42539,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.096153846,"a, and, which, that, in"
42540,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.096153846,"it, was, that, the, a"
42541,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.096153846,"it, that, a, the, virus"
42542,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.096153846,"sars-, cov-2, that, and, sars-cov-2"
42543,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.096153846,"and, to, that, sars-, cov-2"
42544,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.096153846,"genetic, identified, from, species, and"
42545,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.096153846,"and, identified, genetic, are, to"
42546,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.096153846,"and, sars-cov-2, to, bat, in"
42547,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.096153846,"to, sars-cov-2, as, a, from"
42548,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.096153846,"have, been, in, coronaviruses, as"
42549,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.096153846,"in, from, and, a, host,"
42550,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.096153846,"in, between, and, an, bat"
42551,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.096153846,"sars-cov-2, from, to, a, as"
42552,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.096153846,"the, has, genome, that, and"
42553,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.096153846,"the, sars-cov-2, natural, selection, that"
42554,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.096153846,"and, of, that, ratg13, bat"
42555,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.096153846,"sars-cov-2, result, of, the, that"
42556,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.096153846,"sars-cov-2, emergence, zoonotic, with, s"
42557,"this one jumped from bats origin  

into humans","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.096153846,"this, from, origin, into, humans"
42558,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.096153846,"sars-cov-2, the, of, at, from"
42559,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.096153846,"in, the, case, of, that"
42560,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.096153846,"that, with, the, sars-cov-2, in"
42561,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.096153846,"the, that, to, more, related"
42562,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.096153846,"the, a, two, that, in"
42563,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.096153846,"the, in, a, to, that"
42564,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.096153846,"of, at, the, in, a"
42565,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.096153846,"was, the, market, a, of"
42566,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.096153846,"was, by, a, at, the"
42567,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.096153846,"in, the, viruses, to, human"
42568,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.096153846,"was, that, the, in, market"
42569,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.096153846,"of, were, two, from, and"
42570,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.096153846,"the, to, as, of, and"
42571,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.096153846,"that, sars-cov-2, a, the, in"
42572,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.096153846,"in, the, that, sars-cov-2, a"
42573,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.096153846,"the, natural, of, three, or"
42574,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.096153846,"indicated, a, in, of, sars-cov-2"
42575,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.096153846,"of, sars-cov-2, but, the, a"
42576,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.096153846,"sars-cov-2, the, early, of, only"
42577,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.096153846,"the, spread, only, also, in"
42578,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.096153846,"that, a, in, of, sars-cov-2"
42579,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.096153846,"suggests, that, in, the, of"
42580,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.096153846,"sars-cov-2, that, and, is, to"
42581,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.096153846,"that, in, it, was, not"
42582,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.096153846,"and, are, to, is, that"
42583,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.096153846,"sars-cov-2, and, was, in, an"
42584,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.096153846,"in, the, coronavirus, was, that, are, to, at, any, and"
42585,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.096153846,"of, the, at, wiv, are, by, that, or, have, to"
42586,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.096153846,"to, that, the, of, and, have, are, more, sars-cov-2, than"
42587,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.096153846,"that, the, cases, were, with"
42588,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.096153846,"that, the, be, sars-cov-2, infected"
42589,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.096153846,"in, to, the, from, as"
42590,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.096153846,"the, from, a, market, to"
42591,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.096153846,"that, covid-19, in, a, to"
42592,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.096153846,"scientists, that, the, of, to"
42593,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.096153846,"the, animals, to, for, of, that, multiple, infected, other, market"
42594,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.096153846,"and, that, virus, with, coronavirus"
42595,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.096153846,"the, to, on, a, that"
42596,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.096153846,"that, the, bat, a, as"
42597,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.096153846,"a, of, and, that, infect"
42598,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.096153846,"of, to, that, and, a"
42599,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.096153846,"have, and, which, from, human"
42600,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.096153846,"other, can, and, in, their"
42601,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.096153846,"the, natural, of, and, in"
42602,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.096153846,"the, that, first, covid-19, and"
42603,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.096153846,"the, coronavirus, a, sequence, that"
42604,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.096153846,"the, of, study, in, a"
42605,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.096153846,"the, cases, that, with, were"
42606,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.096153846,"january, of, in, the, huanan"
42607,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.096153846,"the, also, to, of, their"
42608,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.096153846,"the, their, and, this, of"
42609,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.096153846,"the, of, coronavirus, is, to"
42610,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.096153846,"virus, from, is, the, of"
42611,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.096153846,"and, that, intermediate, as, pangolin"
42612,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.096153846,"virus, from, is, sars-cov-2, the"
42613,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.096153846,"the, from, and, a, as, according, to, available, that, virus"
42614,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.096153846,"according, to, and, is, that"
42615,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.096153846,"that, has, and, the, genome"
42616,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.096153846,"the, from, for, rna, that"
42617,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.096153846,"to, virus, and, genome, the"
42618,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.096153846,"that, from, a, bat, to"
42619,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.096153846,"sars-cov-2, a, from, to, coronavirus"
42620,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.096153846,"can, from, to, and, the"
42621,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.096153846,"of, the, from, with, and"
42622,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.096153846,"of, sars-cov-2, to, infected, with"
42623,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.096153846,"sars-cov-2, from, the, has, with"
42624,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.096153846,"sars-cov-2, to, a, genetic, and"
42625,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.096153846,"the, by, has, a, that"
42626,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.096153846,"of, the, a, to, that"
42627,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.096153846,"the, of, and, bat, to"
42628,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.096153846,"the, of, human, and, to"
42629,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.096153846,"of, and, the, to, one"
42630,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.096153846,"is, the, to, which, was"
42631,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.096153846,"the, and, of, suggesting, to, that, is, sars-cov-2, animal, by"
42632,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.096153846,"a, the, in, was, to"
42633,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.096153846,"and, a, in, the, to"
42634,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.096153846,"and, to, in, a, genetic"
42635,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.096153846,"at, the, to, in, from"
42636,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.096153846,"the, that, virus, in, animals"
42637,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.096153846,"was, the, of, is, to"
42638,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.096153846,"as, the, was, at, of"
42639,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.096153846,"and, that, the, in, naturally"
42640,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.096153846,"that, the, in, animals, were"
42641,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.096153846,"to, in, more, the, and"
42642,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.096153846,"that, to, is, in, the"
42643,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.096153846,"the, that, in, and, to"
42644,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.096153846,"the, and, in, to, that"
42645,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.096153846,"and, of, in, the, huanan"
42646,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.096153846,"sequence, that, the, of, and"
42647,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.096153846,"studies, to, and, on, the"
42648,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.096153846,"of, the, sequence, and, is"
42649,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.096153846,"reservoir, of, the, possibility, a"
42650,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.096153846,"in, also, only, spread, the"
42651,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.096153846,"sars-cov-2, the, related, that, is"
42652,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.096153846,"is, to, the, that, be"
42653,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.096153846,"that, not, it, was, in"
42654,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.096153846,"have, that, with, as, the"
42655,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.096153846,"the, were, that, in, animals"
42656,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.096153846,"of, that, it, the, was"
42657,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.096153846,"the, for, rna, that, from"
42658,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.096153846,"that, the, from, hosts, for"
42659,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.096153846,"that, could, be, possible, with"
42660,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.096153846,"the, bat, coronavirus, be, of"
42661,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.096153846,"to, the, coronavirus, of, human"
42662,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.096153846,"the, that, to, it, is"
42663,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.096153846,"the, to, sars-cov-2, was, a"
42664,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.096153846,"also, to, sars-cov, that, for"
42665,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.096153846,"to, a, which, was, previously"
42666,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.096153846,"is, to, the, bat, cov,"
42667,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.096153846,"the, of, is, animal, for"
42668,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.096153846,"at, the, was, as, of"
42669,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.096153846,"sars-cov-2, of, and, later, the"
42670,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.096153846,"that, the, and, of, sequence"
42671,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.096153846,"et, the, of, homology, sars-cov-2"
42672,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.096153846,"of, bat, similarity, with, sars-cov-2"
42673,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.096153846,"coronaviruses, from, bat, that, derived"
42674,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.096153846,"a, of, the, from, in"
42675,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.096153846,"as, a, of, the, in"
42676,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.096153846,"the, in, as, a, of"
42677,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.096153846,"a, of, in, the, viruses"
42678,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.096153846,"the, a, from, to, humans"
42679,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.096153846,"coronaviruses, to, the, bats, of"
42680,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.096153846,"the, virus, to, from, and"
42681,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.096153846,"that, and, of, species, by"
42682,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.096153846,"between, and, is, of, to"
42683,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.096153846,"sars-cov-2, is, to, very, likely"
42684,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.096153846,"of, that, sars-cov-2, is, animal"
42685,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.096153846,"the, was, and, of, with"
42686,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.096153846,"virus, with, the, sequence, of"
42687,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.096153846,"the, covid-19, of, virus, in"
42688,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.096153846,"the, of, this, virus, in"
42689,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.096153846,"the, genome, analysis, and, from"
42690,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.096153846,"of, genome, patients, the, in"
42691,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.096153846,"in, and, pigs,, the, as"
42692,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.096153846,"of, the, three, or, natural"
42693,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.096153846,"the, of, to, human, coronavirus"
42694,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.096153846,"the, of, to, coronaviruses, bats"
42695,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.096153846,"related, that, the, more, to"
42696,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.096153846,"of, and, revealed, that, virus"
42697,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.096153846,"of, that, the, covid-19, bat"
42698,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.096153846,"from, that, natural, and, the"
42699,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.096153846,"genome, analysis, the, from, and"
42700,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.096153846,"sars-cov-2, the, and, not, that"
42701,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.096153846,"by, and, the, sars-cov-2, natural"
42702,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.096153846,"the, that, by, from, and"
42703,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.096153846,"et, al., that, and, the"
42704,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.096153846,"studies, the, to, a, and"
42705,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.096153846,"the, is, of, are, and"
42706,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.096153846,"a, on, and, were, in"
42707,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.096153846,"that, of, to, are, the"
42708,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.096153846,"sars-cov-2, in, and, china, from"
42709,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.096153846,"the, virus, in, and, of"
42710,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.096153846,"analysis, of, the, sequence, that"
42711,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.096153846,"the, that, of, with, and"
42712,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.096153846,"most, likely, the, of, to"
42713,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.096153846,"may, of, the, intermediate, hosts"
42714,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.096153846,"the, of, sars-cov-2, that, which"
42715,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.096153846,"and, which, a, that, in"
42716,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.096153846,"a, coronavirus, from, to, sars-cov-2"
42717,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.096153846,"that, coronaviruses, derived, from, bat"
42718,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.096153846,"in, and, can, be, to"
42719,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.096153846,"sars-cov-2, be, a, between, and"
42720,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.096153846,"experimental, of, to, support, the"
42721,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.096153846,"study, that, the, was, to"
42722,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.096153846,"of, that, the, to, which"
42723,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.096153846,"that, to, hypothesis, the, of"
42724,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.096153846,"sars-cov-2, from, a, the, sequence"
42725,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.096153846,"the, sars-cov-2, has, with, a"
42726,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.096153846,"a, similarity, sars-cov-2, which, the"
42727,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.096153846,"the, of, a, it, and"
42728,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.096153846,"to, the, has, and, evolved"
42729,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.096153846,"that, to, the, in, with"
42730,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.096153846,"linked, to, of, the, huanan"
42731,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.096153846,"to, the, that, could, be"
42732,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.096153846,"a, was, the, sars-cov-2, to"
42733,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.096153846,"in, a, of, for, that"
42734,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.096153846,"have, been, as, coronaviruses, in"
42735,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.096153846,"naturally, occurring, such, in, coronaviruses"
42736,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.096153846,"found, to, related, that, this"
42737,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","this one jumped from bats origin  

into humans",0.096153846,"origin, from, this, into, humans"
42738,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.096153846,"to, the, coronavirus, animals, a"
42739,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.096153846,"studies, the, a, to, and"
42740,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.096153846,"genomic, the, and, to, of"
42741,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.096153846,"that, also, for, to, sars-cov"
42742,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.096153846,"this, found, that, related, to"
42743,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.096153846,"the, of, in, viruses, to"
42744,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.096153846,"were, two, of, from, and"
42745,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.096153846,"the, a, of, and, it"
42746,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.096153846,"the, of, a, with, genome"
42747,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.096153846,"the, a, of, to, bat"
42748,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.096153846,"may, a, of, to, the"
42749,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.096153846,"the, covid-19, of, to, that"
42750,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.096153846,"to, is, of, the, covid-19"
42751,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.096153846,"the, virus, genome, to, and"
42752,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.096153846,"to, the, virus, and, was"
42753,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.096153846,"the, in, to, that, not"
42754,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.096153846,"a, the, has, with, sars-cov-2"
42755,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.096153846,"the, from, shares, to, with"
42756,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.096153846,"in, to, humans, an, intermediate"
42757,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.096153846,"in, the, sars-cov-2, from, and"
42758,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.096153846,"of, and, shared, in, the"
42759,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.096153846,"the, from, and, of, with"
42760,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.096153846,"in, a, indicated, of, sars-cov-2"
42761,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.096153846,"in, of, that, a, sars-cov-2"
42762,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.096153846,"similarity, sars-cov-2, in, that, of"
42763,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.096153846,"a, of, has, that, virus"
42764,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.096153846,"from, to, shares, with, the"
42765,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.096153846,"from, market, the, virus, to"
42766,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.096153846,"a, body, of, that, the"
42767,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.096153846,"is, that, a, by, the"
42768,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.096153846,"is, that, a, the, of"
42769,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.096153846,"that, sars-cov-2, sars-, cov-2, and"
42770,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.096153846,"the, of, is, and, sequence"
42771,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.096153846,"analysis, sequence, the, of, that"
42772,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.096153846,"homology, the, of, sars-cov-2, et"
42773,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.096153846,"sars-cov-2, from, in, and, to"
42774,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.096153846,"the, in, as, to, from"
42775,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.096153846,"the, evolved, to, and, has"
42776,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.096153846,"the, from, and, in, sars-cov-2"
42777,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.096153846,"the, of, experimental, to, support"
42778,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.096153846,"amino, acid, the, rbd, to"
42779,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.096153846,"at, found, in, the, sars-cov-2,"
42780,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.096153846,"the, amino, acid, is, to"
42781,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.096153846,"of, and, species, the, animal"
42782,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.096153846,"the, as, in, pigs,, and"
42783,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.096153846,"the, hosts, of, may, intermediate"
42784,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.096153846,"that, the, of, with, ace2"
42785,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.096153846,"in, the, with, that, to"
42786,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.096153846,"and, to, in, the, evolution"
42787,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.096153846,"the, study, that, was, to"
42788,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.096153846,"the, amino, acid, rbd, to"
42789,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.096153846,"obtained, the, of, between, and"
42790,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.096153846,"a, zoonotic, the, to, from"
42791,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.096153846,"the, that, a, additional, evidence"
42792,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.096153846,"2020, samples, of, in, the"
42793,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.096153846,"the, from, has, with, sars-cov-2"
42794,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.096153846,"that, sars-cov-2, highly, genome, the"
42795,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.096153846,"a, that, the, virus, it"
42796,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.096153846,"the, virus, in, to, a"
42797,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.096153846,"virus, the, covid-19, in, of"
42798,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.096153846,"the, as, to, of, and"
42799,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.096153846,"the, and, that, sars-cov-2, in"
42800,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.096153846,"the, to, that, and, bat"
42801,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.096153846,"the, sars-cov-2, to, most, that"
42802,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.096153846,"the, of, and, to, an"
42803,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.096153846,"in, the, and, to, evolution"
42804,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.096153846,"the, of, and, in, shared"
42805,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.096153846,"the, same, in, different, southeast"
42806,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.096153846,"the, of, are, a, bat"
42807,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.096153846,"the, of, this, a, in"
42808,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.096153846,"the, to, bat, in, of"
42809,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.096153846,"to, the, viruses, in, of"
42810,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.096153846,"the, of, that, viruses, same"
42811,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.096153846,"should, of, the, and, viruses, with, similar, to, in, virus"
42812,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.096153846,"is, to, sars-cov-2,, the, which"
42813,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.096153846,"related, genome, which, similar, to"
42814,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.096153846,"sars-cov-2, to, with, genome, the"
42815,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.096153846,"a, at, the, was, by"
42816,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.096153846,"the, genome, closely, a, discovered"
42817,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.096153846,"the, to, which, sars-, and"
42818,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.096153846,"the, closely, related, to, sars-"
42819,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.096153846,"also, the, of, sars-cov-2, to"
42820,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.096153846,"also, the, of, their, to"
42821,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.096153846,"the, are, also, of, sars-cov-2"
42822,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.096153846,"to, the, of, are, sars-cov-2"
42823,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.096153846,"that, sars-, cov-2, and, to"
42824,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.096153846,"are, that, to, and, is"
42825,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.096153846,"of, the, are, that, to"
42826,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.096153846,"the, that, are, of, is"
42827,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.096153846,"ace2, of, that, the, with"
42828,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.096153846,"the, to, that, have, through"
42829,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.096153846,"sars-cov-2, of, and, the, for"
42830,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.096153846,"by, to, the, of, is"
42831,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.096153846,"sars-cov-2, to, with, bat, the"
42832,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.096153846,"to, the, bat, coronaviruses,, and"
42833,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.096153846,"the, covid-19, and, that, sars-cov-2"
42834,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.096153846,"the, that, be, infected, sars-cov-2"
42835,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.096153846,"the, first, it, that, in"
42836,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.096153846,"the, sars-cov-2, in, is, and"
42837,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.096153846,"that, sars-cov-2, when, the, be"
42838,"with the first case being linked to  

a seafood market","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.096153846,"with, the, case, a, seafood"
42839,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.096153846,"the, a, to, from, market"
42840,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.096153846,"of, the, and, was, with"
42841,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.096153846,"the, of, from, and, with"
42842,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.096153846,"the, of, from, at, market, was, to, by, a, and"
42843,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.096153846,"with, the, huanan, and, of, a, to, by, at, market"
42844,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.096153846,"a, of, the, at, also, that, or, have, to, virus"
42845,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.096153846,"the, by, was, from, a, at, market, and, to, of"
42846,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.096153846,"as, intermediate, that, virus, to, for, and, the, species, civets"
42847,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.096153846,"to, the, that, by, researchers, from, wiv, an, and, this"
42848,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.096153846,"a, transmission, from, bats, large, of, and, are, on, markets"
42849,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.096153846,"to, for, the, multiple, of, infected, animals, market, other, that"
42850,"expended to make the simple point 

that COVID-19 had a natural origin.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.096153846,"to, the, covid-19, had, a"
42851,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.096153846,"the, covid-19, to, in, market"
42852,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.096153846,"the, of, and, suggesting, that, sars-cov-2, is, animal, to, by"
42853,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.096153846,"the, by, a, at, huanan, market, and, to, of, with"
42854,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.096153846,"the, live, and, were, in, with, all, by, however,, of, a, to, that, infected, at"
42855,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.096153846,"of, in, the, huanan, january"
42856,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.096153846,"huanan, in, the, and, of"
42857,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.096153846,"and, in, were, a, on"
42858,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.096153846,"of, linked, to, the, huanan"
42859,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.096153846,"the, of, in, samples, 2020"
42860,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.096153846,"the, and, to, a, market"
42861,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.096153846,"is, between, and, of, to"
42862,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.096153846,"the, and, that, animal, to"
42863,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.096153846,"to, a, in, and, animal"
42864,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.096153846,"the, a, at, and, to"
42865,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.096153846,"of, the, with, that, and"
42866,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.096153846,"of, also, the, in, these"
42867,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.096153846,"the, also, that, are, covid-19"
42868,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.096153846,"virus, the, to, that, sars-cov-2"
42869,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.096153846,"the, to, that, contact, with"
42870,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.096153846,"to, that, sars-cov-2, the, virus"
42871,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.096153846,"found, that, with, the, to"
42872,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","expended to make the simple point 

that COVID-19 had a natural origin.",0.096153846,"covid-19, had, a, to, the"
42873,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.096153846,"sars-cov-2, and, from, in, china"
42874,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.096153846,"in, a, was, humans, and"
42875,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.096153846,"was, an, sars-cov-2, and, in"
42876,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.096153846,"the, with, that, sars-cov-2, in"
42877,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.096153846,"that, sars-cov-2, natural, selection, the"
42878,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.096153846,"on, the, a, that, to"
42879,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.096153846,"that, sars-cov-2, not, a, to"
42880,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.096153846,"to, is, of, the, bats"
42881,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.096153846,"to, sars-cov-2,, is, which, the"
42882,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.096153846,"the, to, that, a, not"
42883,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.096153846,"that, in, similarity, of, sars-cov-2"
42884,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.096153846,"sars-cov-2, the, of, that, it"
42885,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.096153846,"to, the, in, that, pangolins"
42886,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.096153846,"from, the, of, these, and"
42887,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.096153846,"that, sars-cov-2, is, related, the"
42888,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.096153846,"the, that, sars-cov-2, and, not"
42889,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.096153846,"and, in, all, related, the"
42890,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.096153846,"that, sars-cov-2, the, of, and"
42891,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.096153846,"a, to, the, that, not"
42892,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.096153846,"a, of, that, the, new"
42893,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.096153846,"discovered, a, closely, the, genome"
42894,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.096153846,"the, evidence, in, this, found"
42895,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.096153846,"that, the, evidence, a, additional"
42896,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.096153846,"a, study, in, the, of"
42897,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.096153846,"to, the, of, and, sars-cov"
42898,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.096153846,"the, of, to, identity, and"
42899,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.096153846,"sars-, and, which, to, the"
42900,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.096153846,"a, is, the, that, thus"
42901,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.096153846,"the, as, a, that, bat"
42902,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.096153846,"the, from, for, that, hosts"
42903,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.096153846,"that, from, a, bat, intermediate"
42904,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.096153846,"that, the, of, same, viruses"
42905,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.096153846,"the, of, to, and, genomic"
42906,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.096153846,"are, of, many, a, large"
42907,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.096153846,"and, can, be, to, in"
42908,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.096153846,"are, to, that, in, covs"
42909,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.096153846,"to, humans, an, intermediate, in"
42910,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.096153846,"covid-19, to, the, market, in"
42911,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.096153846,"is, that, was, the, virus"
42912,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.096153846,"it, was, that, the, of"
42913,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.096153846,"to, coronaviruses,, the, bat, and"
42914,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.096153846,"the, outbreak, in, animals, china"
42915,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.096153846,"the, coronavirus, to, animals, a"
42916,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.096153846,"of, reservoir, viruses, in, bats"
42917,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.096153846,"that, the, virus, in, animals"
42918,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.096153846,"southeast, different, in, the, same"
42919,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.096153846,"that, contact, with, to, the"
42920,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.096153846,"the, of, that, is, natural"
42921,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.096153846,"transmission, of, between, and, or"
42922,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.096153846,"their, in, can, other, and"
42923,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.096153846,"of, to, and, in, bats"
42924,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.096153846,"and, the, to, be, is"
42925,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.096153846,"all, the, and, in, related"
42926,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.096153846,"are, a, large, but, of"
42927,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.096153846,"from, bats, a, and, large, of, transmission, markets, are, on"
42928,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.096153846,"the, in, of, and, a"
42929,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.096153846,"in, the, of, is, sars-cov-2"
42930,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.096153846,"is, at, the, in, from"
42931,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.096153846,"the, virus, is, of, from"
42932,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.096153846,"sars-cov-2, is, virus, from, the"
42933,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.096153846,"of, the, sequence, virus, with"
42934,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.096153846,"according, to, available, a, virus, that, from, and, the, as"
42935,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.096153846,"with, the, and, of, all, a, to, however,, that, were, in, live, infected, by, at"
42936,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.096153846,"that, the, of, and, a"
42937,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.096153846,"to, the, which, from, infection"
42938,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.096153846,"the, to, one, of, and"
42939,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.096153846,"a, from, to, humans, the"
42940,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.096153846,"the, that, wiv, to, have, are, by, of, or, at"
42941,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.096153846,"that, a, the, virus, or, of, at, also, have, to"
42942,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.096153846,"also, a, origin, are, the"
42943,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.096153846,"a, to, that, from, bat"
42944,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.096153846,"sars-cov-2, to, a, that, not"
42945,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.096153846,"that, bat, a, from, intermediate"
42946,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.096153846,"that, a, to, intermediate, sars-cov-2"
42947,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.096153846,"no, such, in, to, sars-cov-2"
42948,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.096153846,"in, sars-cov-2, to, that, may"
42949,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.096153846,"the, but, a, of, sars-cov-2"
42950,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.096153846,"a, the, possibility, reservoir, of"
42951,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.096153846,"the, are, also, sars-cov-2, of"
42952,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.096153846,"the, of, are, is, that"
42953,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.096153846,"the, by, sars-cov-2, natural, and"
42954,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.096153846,"such, to, sars-cov-2, no, in"
42955,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.096153846,"the, bat, pangolin, is, which"
42956,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.096153846,"is, the, bat, its, in"
42957,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.096153846,"to, sars-cov-2, from, and, that"
42958,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.096153846,"with, bat, of, sars-cov-2, similarity"
42959,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.096153846,"the, by, that, and, from"
42960,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.096153846,"from, the, wiv, to, that, this, and, researchers, by, an"
42961,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.096153846,"that, has, the, and, to"
42962,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.096153846,"the, to, be, with, of"
42963,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.096153846,"the, of, these, in, also"
42964,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.096153846,"sarbecoviruses,, is, a, that, naturally"
42965,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.096153846,"in, a, that, the, two"
42966,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.096153846,"the, coronavirus, that, sequence, a"
42967,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.096153846,"a, has, that, by, the"
42968,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.096153846,"naturally, occurring, in, coronaviruses, such"
42969,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.096153846,"that, the, or, bats, pangolins"
42970,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.096153846,"the, to, that, and, sars-cov-2"
42971,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.096153846,"the, that, covid-19, are, also"
42972,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.096153846,"the, that, a, sars-cov-2, to"
42973,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.096153846,"a, the, are, that, to"
42974,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.096153846,"the, of, which, that, to"
42975,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.096153846,"genome, of, the, patients, in"
42976,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.096153846,"a, was, to, which, previously"
42977,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.096153846,"human, viruses, in, to, the"
42978,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.096153846,"a, the, which, similarity, sars-cov-2"
42979,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.096153846,"a, of, region, in, sars-cov-2"
42980,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.096153846,"related, to, which, similar, genome"
42981,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.096153846,"be, possible, with, that, could"
42982,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.096153846,"et, al., that, the, and"
42983,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.096153846,"to, the, of, may, a"
42984,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.096153846,"that, sars-cov-2, a, to, intermediate"
42985,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.096153846,"sars-cov-2, the, of, that, sequences"
42986,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.096153846,"in, bats, to, and, the"
42987,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.096153846,"the, in, pangolins, to, that"
42988,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.096153846,"the, to, be, closest, in"
42989,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.096153846,"of, sars-cov-2, novel, coronavirus, that"
42990,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.096153846,"in, the, that, sars-cov-2, originated"
42991,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.096153846,"that, the, pangolin, to, sars-cov-2."
42992,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.096153846,"the, is, to, bat, cov,"
42993,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.096153846,"is, very, likely, sars-cov-2, to"
42994,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.096153846,"to, is, ratg13, in, bat"
42995,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.096153846,"is, which, the, bat, pangolin"
42996,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.096153846,"that, of, bats, sars-cov-2, the"
42997,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.096153846,"the, of, and, their, this"
42998,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.096153846,"pangolin, sars-cov-2, the, this, of"
42999,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.096153846,"the, that, to, have, are, more, than, of, and, sars-cov-2"
43000,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.096153846,"origin, are, for, the, and"
43001,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.096153846,"virus, genome, the, bat, and"
43002,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.096153846,"the, of, obtained, and, between"
43003,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.096153846,"to, studies, on, the, and"
43004,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.096153846,"the, of, that, to, hypothesis"
43005,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.096153846,"of, are, bat, a, the"
43006,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.096153846,"the, a, to, of, with"
43007,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.096153846,"to, of, that, ratg13, bat"
43008,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.096153846,"from, a, host,, and, in"
43009,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.096153846,"the, that, of, are, and"
43010,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.096153846,"to, sars-cov-2, in, the, and"
43011,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.096153846,"in, the, of, suggests, that"
43012,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.096153846,"the, of, and, in, this"
43013,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.096153846,"for, the, natural, of, and"
43014,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.096153846,"the, that, of, natural, for"
43015,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.096153846,"that, the, of, and, for"
43016,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.096153846,"of, and, that, virus, with"
43017,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.096153846,"an, between, and, in, bat"
43018,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.096153846,"the, of, that, bat, and"
43019,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.096153846,"of, the, in, that, can"
43020,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.096153846,"to, the, of, possibly, from"
43021,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.096153846,"that, of, to, the, sars-cov-2"
43022,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.096153846,"that, of, sars-cov-2, the, which"
43023,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.096153846,"the, to, that, in, of"
43024,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.096153846,"that, the, be, when, sars-cov-2"
43025,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.096153846,"from, virus, transmission, to, the"
43026,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.096153846,"the, a, zoonotic, to, of"
43027,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.096153846,"of, the, virus, from, with"
43028,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.096153846,"a, of, to, with, zoonotic"
43029,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.096153846,"sars-cov-2, a, between, and, be"
43030,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.096153846,"is, that, of, sars-cov-2, animal"
43031,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.096153846,"this, virus, the, in, of"
43032,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.096153846,"this, of, a, in, the"
43033,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.096153846,"of, is, that, in, populations"
43034,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.096153846,"sars-cov-2, the, that, originated, in"
43035,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.096153846,"to, and, of, it, is"
43036,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.096153846,"a, of, sars-cov-2, in, region"
43037,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.096153846,"the, a, are, and, for"
43038,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.096153846,"a, the, also, are, origin"
43039,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.096153846,"the, and, for, are, origin"
43040,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.096153846,"infected, to, with, of, sars-cov-2"
43041,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.096153846,"in, that, for, a, of"
43042,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.096153846,"that, may, to, sars-cov-2, in"
43043,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.096153846,"that, of, sars-cov-2, novel, coronavirus"
43044,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.096153846,"to, of, zoonotic, a, with"
43045,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.096153846,"are, a, large, of, many"
43046,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.096153846,"covs, that, are, to, in"
43047,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.096153846,"at, the, in, found, sars-cov-2,"
43048,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.096153846,"a, of, at, the, in"
43049,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.096153846,"in, can, that, the, of"
43050,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.096153846,"of, be, the, coronavirus, bat"
43051,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.096153846,"is, the, bat, in, its"
43052,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.096153846,"closest, to, the, in, be"
43053,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.096153846,"and, that, bat, ratg13, of"
43054,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.096153846,"is, to, that, of, and"
43055,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.096153846,"according, to, is, that, and"
43056,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.096153846,"is, of, to, related, in"
43057,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.096153846,"to, that, of, and, is"
43058,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.096153846,"is, to, in, bat, ratg13"
43059,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.096153846,"of, that, to, bat, ratg13"
43060,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.096153846,"of, that, is, in, populations"
43061,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.096153846,"is, and, it, to, of"
43062,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.096153846,"the, have, as, of, host"
43063,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.096153846,"that, found, with, to, the"
43064,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.096153846,"sars-cov-2., pangolin, to, the, that"
43065,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.096153846,"closely, related, sars-, to, the"
43066,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.096153846,"s, with, sars-cov-2, emergence, zoonotic"
43067,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.096153846,"and, the, of, to, similar, viruses, should, with, in, virus"
43068,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.096,"to, the, sars, for, a, reservoir, in, of, that, sars-related, found, contained"
43069,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.096,"the, of, for, reservoir, in, found, a, to, sars, sars-related, that, contained"
43070,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.096,"and, the, be, that, or, for, zoonotic, of, in, study, from, a"
43071,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.096,"or, bats, on, the, infected, of, are, such, civets, and, in, may"
43072,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.096,"the, for, zoonotic, be, and, a, in, of, study, from, that, or"
43073,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.096,"civets, infected, bats, in, the, such, or, and, of, may, are, on"
43074,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.095890411,"a, which, to, in, called, and, sars-cov"
43075,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.095890411,"the, of, virus, and, with, to, into"
43076,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.095890411,"to, with, the, of, and, into, virus"
43077,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.095890411,"the, of, with, and, that, into, in"
43078,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.095890411,"the, of, to, ace2, is, a, that"
43079,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.095890411,"the, which, to, in, identical, at, was"
43080,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.095890411,"that, are, the, sars-cov-2, selection, natural, and"
43081,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.095890411,"the, of, were, a, two, from, and"
43082,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.095890411,"the, by, from, a, at, and, of"
43083,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.095890411,"the, of, and, in, with, that, into"
43084,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.095890411,"in, the, joint, report, and, of, to"
43085,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.095890411,"the, genetic, of, more, to, and, in"
43086,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.095890411,"the, and, of, or, to, that, in, is, sars-cov-2, sars, more, than, by, at"
43087,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.095890411,"the, a, to, in, wet, animals, market"
43088,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.095890411,"in, is, that, the, covid-19, ever, first"
43089,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.095890411,"in, it, is, that, the, and, world"
43090,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.095890411,"in, the, of, is, at, that, virus"
43091,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.095890411,"a, was, that, the, is, to, of"
43092,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.095890411,"the, and, a, to, that, of, but"
43093,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.095890411,"a, the, of, and, in, that, were"
43094,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.095890411,"and, to, the, of, that, in, a"
43095,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.095890411,"cases, the, that, or, of, in, this"
43096,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.095890411,"the, of, which, to, and, virus, identical"
43097,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.095890411,"and, from, in, to, that, the, bats"
43098,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.095890411,"origin, to, virus, that, in, and, the"
43099,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.095890411,"as, and, the, of, rbd, to, be"
43100,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.095890411,"by, and, to, that, sars-cov-2, is, of"
43101,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.095890411,"in, the, and, of, 2020, from, between"
43102,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.095890411,"the, dromedary, as, a, of, to, and"
43103,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.095890411,"however,, in, the, and, are, to, that"
43104,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.095890411,"a, of, the, from, and, two, were"
43105,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.095890411,"and, from, were, the, of, bats, natural"
43106,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.095890411,"bat, had, to, animal, in, for, the, markets, while, live, were, zoonotic, of, and"
43107,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.095890411,"of, with, a, to, and, the, in"
43108,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.095890411,"in, the, and, to, sars-cov-2, as, cluster"
43109,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.095890411,"as, the, to, be, rbd, of, and"
43110,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.095890411,"the, and, that, in, however,, are, to"
43111,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.095890411,"the, that, in, use, ace2,, and, to"
43112,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.095890411,"the, has, a, that, sequences, in, coronaviruses"
43113,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.095890411,"that, are, the, sars-cov-2, to, in, and"
43114,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.095890411,"in, the, by, and, of, bat, are"
43115,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.095890411,"with, a, to, other, and, the, in"
43116,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.095890411,"in, the, ever, that, covid-19, first, is"
43117,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.095890411,"the, and, in, world, it, that, is"
43118,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.095890411,"and, the, it, be, that, sars-cov-2, in"
43119,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.095890411,"a, of, the, from, by, and, at"
43120,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.095890411,"and, of, the, to, markets, live, animal, in, were, while, had, bat, for, zoonotic"
43121,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.095890411,"in, the, case, of, a, and, market"
43122,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.095890411,"in, the, of, to, with, and, a"
43123,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.095890411,"in, a, with, other, and, to, the"
43124,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.095890411,"a, other, to, in, with, the, and"
43125,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.095890411,"the, that, to, more, sars, in, is, by, than, of, or, and, sars-cov-2, at"
43126,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.095890411,"of, sequences, in, the, and, that, with"
43127,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.095890411,"this, of, cases, the, in, that, or"
43128,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.095890411,"in, it, that, the, be, and, sars-cov-2"
43129,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.095890411,"sars-cov-2, a, that, its, into, the, for"
43130,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.095890411,"the, joint, report, in, to, of, and"
43131,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.095890411,"of, the, from, in, between, and, 2020"
43132,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.095890411,"the, that, its, for, sars-cov-2, into, a"
43133,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.095890411,"a, the, of, is, that, to, ace2"
43134,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.095890411,"in, the, and, to, use, ace2,, that"
43135,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.095890411,"in, the, of, and, to, more, genetic"
43136,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.095890411,"more, than, the, to, in, of, and"
43137,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.095890411,"sars-cov, and, to, in, a, called, which"
43138,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.095890411,"identical, at, the, to, which, was, in"
43139,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.095890411,"the, in, a, to, animals, wet, market"
43140,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.095890411,"the, virus, which, to, identical, of, and"
43141,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.095890411,"the, of, at, a, virus, in, animal"
43142,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.095890411,"and, the, market, in, of, a, was"
43143,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.095890411,"the, market, in, of, case, and, a"
43144,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.095890411,"in, with, the, sars-cov-2, is, of, guangdong"
43145,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.095890411,"and, a, to, the, of, dromedary, as"
43146,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.095890411,"this, sars-cov-2, and, to, the, that, in"
43147,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.095890411,"a, sequences, in, the, has, that, coronaviruses"
43148,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.095890411,"that, sars-cov-2, natural, selection, and, are, the"
43149,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.095890411,"the, to, that, are, sars-cov-2, in, and"
43150,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.095890411,"that, a, was, the, of, is, to"
43151,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.095890411,"and, to, this, the, that, sars-cov-2, in"
43152,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.095890411,"is, and, that, of, sars-cov-2, to, by"
43153,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.095890411,"in, to, the, sars-cov-2, cluster, and, as"
43154,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.095890411,"of, and, are, by, bat, in, the"
43155,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.095890411,"in, guangdong, is, with, sars-cov-2, the, of"
43156,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.095890411,"in, of, to, the, virus, that, is"
43157,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.095890411,"at, the, of, in, virus, that, is"
43158,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.095890411,"the, of, is, in, virus, to, that"
43159,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.095890411,"the, of, a, animal, in, virus, at"
43160,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.095890411,"that, the, in, bats, and, to, from"
43161,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.095890411,"the, of, bats, were, natural, from, and"
43162,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.095890411,"to, and, of, is, that, related, in"
43163,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.095890411,"that, a, the, of, and, but, to"
43164,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.095890411,"and, in, to, related, that, of, is"
43165,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.095744681,"and, the, of, bat, to, with, into, which, virus"
43166,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.095744681,"that, a, the, of, sars-cov-2, and, he, to, an"
43167,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.095744681,"that, are, the, to, be, with, in, of, and"
43168,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.095744681,"infected, to, animal, in, the, wet, were, zoonotic, of"
43169,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.095744681,"the, that, was, have, coronavirus, of, and, not, at"
43170,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.095744681,"the, first, to, this, it, that, has, been, of"
43171,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.095744681,"and, that, have, not, the, coronavirus, was, at, of"
43172,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.095744681,"the, is, of, sars-cov-2, or, to, closely, related, in"
43173,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.095744681,"at, are, known, and, in, the, that, to, sars"
43174,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.095744681,"he, sars-cov-2, of, to, a, that, an, and, the"
43175,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.095744681,"for, an, to, samples, at, the, market, of, no"
43176,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.095744681,"the, market, that, have, for, of, to, all, an"
43177,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.095744681,"the, was, first, to, a, that, bat, and, coronavirus"
43178,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.095744681,"an, bat, to, a, from, in, the, of, horseshoe"
43179,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.095744681,"or, the, species, of, as, and, in, may, also"
43180,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.095744681,"the, to, closely, related, in, is, of, or, sars-cov-2"
43181,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.095744681,"in, the, or, china, one, of, and, species, horseshoe"
43182,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.095744681,"to, with, the, of, and, into, which, bat, virus"
43183,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.095744681,"the, of, at, this, that, a, virus, in, animal"
43184,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.095744681,"the, of, genome, most, closely, a, bat, coronavirus, discovered"
43185,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.095744681,"of, virus, most, to, the, bat, coronaviruses,, and, for"
43186,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.095744681,"the, first, to, bat, coronavirus, and, that, was, a"
43187,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.095744681,"the, of, infected, were, to, wet, animal, in, zoonotic"
43188,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.095744681,"the, to, in, from, an, of, a, horseshoe, bat"
43189,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.095744681,"the, one, or, species, of, horseshoe, in, and, china"
43190,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.095744681,"the, from, various, all, to, a, also, bat, and"
43191,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.095744681,"to, an, for, the, of, no, at, market, samples"
43192,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.095744681,"have, to, an, for, the, of, market, all, that"
43193,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.095744681,"the, of, covid-19, were, associated, with, huanan, market, in"
43194,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.095744681,"the, that, known, to, are, sars, in, and, at"
43195,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.095744681,"a, of, the, coronavirus, bat, most, discovered, genome, closely"
43196,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.095744681,"of, to, the, for, bat, most, coronaviruses,, and, virus"
43197,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.095744681,"associated, with, the, huanan, of, were, covid-19, in, market"
43198,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.095744681,"that, it, to, this, first, the, of, has, been"
43199,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.095744681,"may, also, in, of, species, and, the, as, or"
43200,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.095744681,"are, the, of, and, be, in, with, that, to"
43201,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.095744681,"bat, to, a, from, the, all, and, also, various"
43202,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.095744681,"this, that, a, the, virus, animal, of, in, at"
43203,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.095652174,"the, viruses, that, are, in, by, of, and, into, sars-cov-2, at"
43204,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.095652174,"since, at, the, it, that, its, for, of, this, a, by"
43205,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.095652174,"of, the, by, that, sars-cov-2, and, are, at, in, viruses, into"
43206,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.095652174,"that, of, to, coronavirus, found, in, pangolin, with, sars-cov-2, over, the"
43207,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.095652174,"not, covs, species,, of, but, have, zoonotic, and, the, to, animals"
43208,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.095652174,"sars-cov-2, of, the, to, pangolin, in, with, found, over, that, coronavirus"
43209,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.095652174,"its, that, it, this, at, the, by, a, of, since, for"
43210,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.095652174,"and, of, the, have, to, animals, species,, but, not, zoonotic, covs"
43211,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.095238095,"the, a, of, that, from, and"
43212,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.095238095,"in, of, the, bats, and, naturally"
43213,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.095238095,"of, that, the, a, from, or"
43214,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.095238095,"or, body, of, and, in, bats"
43215,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.095238095,"that, a, of, and, pangolins, the"
43216,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.095238095,"a, bat, in, sars-cov-2"
43217,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.095238095,"sars-cov-2, and, bat, pangolin"
43218,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.095238095,"virus, from, humans, the"
43219,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.095238095,"the, and, humans, from"
43220,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.095238095,"from, 2, the, of"
43221,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.095238095,"the, from, are, two, in, viruses"
43222,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.095238095,"from, bats, the, as"
43223,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.095238095,"the, from, two, in"
43224,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.095238095,"are, in, the, sars"
43225,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.095238095,"of, one, bats, for, coronavirus, and, were, more, than, virus"
43226,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.095238095,"and, have, sequences, to"
43227,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.095238095,"and, similar, bat, in"
43228,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.095238095,"and, of, many, to"
43229,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.095238095,"of, sars-cov-2, to, in"
43230,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.095238095,"sars-cov-2, to, in, which"
43231,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.095238095,"and, in, to, of, bats, sars-cov-2"
43232,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.095238095,"infected, from, and, of"
43233,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.095238095,"bats, species, of, and"
43234,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.095238095,"were, bats, and, from"
43235,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.095238095,"species, bats, and, by"
43236,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.095238095,"the, many, and, within"
43237,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.095238095,"the, viruses,, to, genetic"
43238,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.095238095,"whole, genome, virus, in"
43239,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.095238095,"genome, sars-cov-2, virus, in"
43240,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.095238095,"for, a, coronavirus, and"
43241,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.095238095,"a, and"
43242,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.095238095,"are, the, in, bats"
43243,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.095238095,"with, emergence, resulted, from"
43244,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.095238095,"to, may, with, the, bat, and"
43245,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.095238095,"and, of, which, the, to, human"
43246,"Bats have been reported as being the rich source of 

coronaviruses","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.095238095,"as, being, the, of"
43247,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.095238095,"in, to, is, of, the, was"
43248,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.095238095,"a, of, with, to, the, sars-cov-2"
43249,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.095238095,"have, that, by, of"
43250,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.095238095,"of, that, by, a"
43251,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.095238095,"of, that, sars-cov-2, t"
43252,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.095238095,"that, a, origin, of"
43253,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.095238095,"the, of, that, from, to, viruses,"
43254,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.095238095,"is, been, identified, from"
43255,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.095238095,"in, the, of, an, a, that, virus, to, human, and"
43256,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.095238095,"the, to, bat, and, human, sars-cov-2"
43257,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.095238095,"in, a, of, to, have, the, is, found"
43258,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.095238095,"the, of, is, in, found, a, to, genetic"
43259,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.095238095,"the, of, and, a, found, in, human, to"
43260,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.095238095,"and, to, the, of, sars-cov-2, have, in, a"
43261,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.095238095,"to, sars-cov-2, the, be, of, recombination"
43262,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.095238095,"be, a, in, the, sars-cov-2, human"
43263,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.095238095,"in, the, because, genetic, virus, had, no, laboratory"
43264,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.095238095,"in, is, the, virus, genetic, was"
43265,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.095238095,"that, by, a, virus, the, sars-cov-2"
43266,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.095238095,"viral, of, the, are"
43267,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.095238095,"and, their, with, sars-cov-2"
43268,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.095238095,"and, to, of, many"
43269,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.095238095,"to, sars-cov-2, the, several"
43270,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.095238095,"a, the, of, is, that, to"
43271,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.095238095,"that, sars-cov-2, the, genome"
43272,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.095238095,"a, of, the, found"
43273,"Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.095238095,"based, on, of, origin"
43274,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.095238095,"the, of, and, including"
43275,Bats are likely reservoir hosts for SARS-CoV-2,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.095238095,"are, reservoir"
43276,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.095238095,"the, sars-cov-2, and, to, bat, human"
43277,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.095238095,"the, sars-cov-2, and, ratg13"
43278,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.095238095,"the, that, sars-cov-2, virus"
43279,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.095238095,"identity, to, ratg13, and"
43280,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.095238095,"pangolin, of, intermediate, and"
43281,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.095238095,"similar, and, that, in"
43282,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.095238095,"of, and, sars-cov-2, with"
43283,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.095238095,"the, genome, sars-cov-2, and"
43284,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.095238095,"to, most"
43285,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.095238095,"a, in, the, human"
43286,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.095238095,"the, of, as, a, bats, that, in, its"
43287,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.095238095,"of, the, viruses, have"
43288,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.095238095,"that, the, of, is, to, a"
43289,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.095238095,"bats, are, a, of, virus, the"
43290,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.095238095,"as, to, the, of, be, a"
43291,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.095238095,"a, virus, that, with, the, in"
43292,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.095238095,"the, to, for, a, is, also"
43293,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.095238095,"that, a, to, in, an, host"
43294,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.095238095,"that, human, in, and"
43295,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.095238095,"the, to, that, original"
43296,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.095238095,"and, the, to, a, that, in, virus, is"
43297,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.095238095,"sars-cov-2, to, as, the"
43298,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.095238095,"of, the, as, from"
43299,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.095238095,"of, to, the, for"
43300,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.095238095,"of, from, close, sars-cov-2"
43301,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.095238095,"the, had, of, and"
43302,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.095238095,"the, only, wuhan, in, of, before, and, had"
43303,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.095238095,"the, been, in, of, and, china"
43304,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.095238095,"of, to, the, animal"
43305,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.095238095,"to, the, likely, of"
43306,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.095238095,"were, it, the, in"
43307,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.095238095,"that, of, to, is, in, the"
43308,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.095238095,"zoonotic, animal, the, likely"
43309,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.095238095,"to, the, an, animal, coronavirus, a, of, is"
43310,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.095238095,"the, species, of, and"
43311,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","All human coronaviruses have animal origins, namely, natu- 

ral hosts",0.095238095,"animal, human"
43312,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","All human coronaviruses have animal origins, namely, natu- 

ral hosts",0.095238095,"animal, hosts"
43313,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.095238095,"of, be, the, bats"
43314,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.095238095,"the, from, that, intermediate, hosts, for"
43315,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.095238095,"as, the, for, and"
43316,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.095238095,"of, the, early, sars-cov-2, genomic, at"
43317,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.095238095,"the, covid-19, of, sars-cov-2"
43318,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.095238095,"sequence, identity, with, sars-cov-2"
43319,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.095238095,"the, of, at, sars-cov-2"
43320,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.095238095,"in, wuhan, the, was"
43321,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.095238095,"the, in, wuhan, province,"
43322,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",zoonotic origins of SARS-CoV-2 by natural evolution,0.095238095,"by, zoonotic"
43323,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.095238095,"is, sars-cov-2, to, the"
43324,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.095238095,"of, into, and, to"
43325,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.095238095,"to, and, humans,, the"
43326,Wet Market animals maintained in poor conditions,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.095238095,"animals, in"
43327,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.095238095,"the, bat, that, sars-cov-2"
43328,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.095238095,"in, of, the, that, analysis, is"
43329,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.095238095,"lineage, the, that, of, sars-cov-2, in"
43330,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.095238095,"in, the, that, sars-cov-2"
43331,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.095238095,"that, the, protein, of"
43332,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.095238095,"the, that, genome, to"
43333,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.095238095,"are, of, the, viral"
43334,"the close relation  

between SARS coronavirus and 2019-nCoV","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.095238095,"the, sars"
43335,"Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan","civet cats and raccoon dogs  

are the intermediate hosts",0.095238095,"raccoon, dogs"
43336,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","civet cats and raccoon dogs  

are the intermediate hosts",0.095238095,"the, and, hosts, are"
43337,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.095238095,"are, coronaviruses, and, for, in, with"
43338,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.095238095,"a, and, with, the, from, in"
43339,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.095238095,"the, and, in, coronaviruses, that, any"
43340,"Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor","with the first case being linked to  

a seafood market",0.095238095,"to, a"
43341,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","with the first case being linked to  

a seafood market",0.095238095,"a, to"
43342,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.095238095,"from, the, this, is"
43343,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.095238095,"through, the, of, to"
43344,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.095238095,"bats, the, be, of, to, in, has, been"
43345,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.095238095,"the, origin, that, and"
43346,zoonotic origins of SARS-CoV-2 by natural evolution,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.095238095,"zoonotic, by"
43347,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.095238095,"in, the, which, that"
43348,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.095238095,"that, was, who, a"
43349,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.095238095,"the, that, by, a"
43350,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.095238095,"it, that, a, the"
43351,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.095238095,"the, that, was, virus"
43352,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.095238095,"that, a, the, virus"
43353,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.095238095,"to, that, has, been, identified, and"
43354,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.095238095,"as, a, studies, animal, and, in, an, to, found, from, host, reservoir"
43355,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.095238095,"and, from, to, in, have, been"
43356,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.095238095,"evidence, the, that, of, to, from"
43357,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.095238095,"that, the, genome, sars-cov-2"
43358,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.095238095,"the, that, has, and"
43359,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.095238095,"the, could, have, and"
43360,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.095238095,"and, that, the, has"
43361,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.095238095,"the, genomic, are, that"
43362,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.095238095,"that, genomic, the, sars-cov-2"
43363,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.095238095,"of, not, that, the"
43364,"unnatural origin of SARS-CoV-2, but these people are 

simply wrong","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.095238095,"of, people"
43365,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.095238095,"of, genomes, and, ancestral"
43366,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.095238095,"the, sars-cov-2, at, that"
43367,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.095238095,"the, two, are, from, viruses, in"
43368,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.095238095,"sars-cov-2, at, the, early, of, genomic"
43369,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.095238095,"a, zoonotic, origin, are, the, and"
43370,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.095238095,"of, sars-cov-2, into, the"
43371,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.095238095,"to, the, of, transmission"
43372,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.095238095,"that, the, with, in, market, of"
43373,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.095238095,"in, with, and, sars-cov-2, at, the"
43374,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.095238095,"that, related, to, the"
43375,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.095238095,"the, in, that, a"
43376,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.095238095,"in, the, that, to, huanan, market"
43377,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.095238095,"that, related, to, in"
43378,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.095238095,"a, the, huanan, with, at, and, market, of"
43379,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.095238095,"in, the, and, of, huanan, market"
43380,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.095238095,"the, of, and, this"
43381,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.095238095,"of, the, huanan, was"
43382,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.095238095,"huanan, the, was, of"
43383,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.095238095,"was, at, a, market"
43384,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.095238095,"at, the, et, of"
43385,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.095238095,"a, of, the, virus"
43386,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.095238095,"of, a, the, virus"
43387,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.095238095,"in, were, to, the"
43388,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.095238095,"the, in, more, than"
43389,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.095238095,"the, to, in, than"
43390,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.095238095,"at, that, the, sars-cov-2"
43391,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.095238095,"in, the, huanan, market"
43392,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.095238095,"in, sars-cov-2, and, the"
43393,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.095238095,"that, sars-cov-2, the, genomic"
43394,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.095238095,"and, that, the, likely"
43395,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.095238095,"in, and, sars-cov-2, that, the, than"
43396,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.095238095,"into, to, of, and"
43397,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.095238095,"two, of, were, in"
43398,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.095238095,"in, the, of, a, to, spillover"
43399,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.095238095,"from, zoonotic, a, with"
43400,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.095238095,"that, a, sars-cov-2, the"
43401,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.095238095,"and, the, was, to"
43402,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.095238095,"of, the, from, in, and, without"
43403,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.095238095,"sars-cov-2, including, the, and, in, of"
43404,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.095238095,"the, in, a, spillover, to, of"
43405,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.095238095,"a, sars-cov-2, the, of, from, in"
43406,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.095238095,"have, in, to, the, of, sars-cov-2"
43407,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.095238095,"is, to, a, of, an, animal, coronavirus, the"
43408,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.095238095,"is, evidence, at, that, the, as, of, a"
43409,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.095238095,"the, is, that, for, of, 2, to, by, experts, a, had, an"
43410,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.095238095,"is, to, that, from, an, and"
43411,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.095238095,"laboratory, because, no, had, the, virus, genetic, in"
43412,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.095238095,"in, the, of, virus, for, more, to, and"
43413,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.095238095,"there, are, other, to, in, more, the, and"
43414,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.095238095,"in, of, to, the, for, and, had, at, viruses, more, other, virus"
43415,Genetic evidence suggesting otherwise is yet to be presented.,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.095238095,"evidence, is"
43416,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.095238095,"in, a, sars-cov-2, that"
43417,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.095238095,"most, that, was, the, cause, of, sars-cov-2, and, is, to"
43418,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.095238095,"infected, animals, the, wet"
43419,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.095238095,"that, sars-cov-2, the, infected"
43420,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.095238095,"the, genome, that, to"
43421,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.095238095,"that, a, in, genome"
43422,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.095238095,"a, in, humans, following"
43423,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.095238095,"the, two, market, in"
43424,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.095238095,"the, have, to, a, of, is, found, in"
43425,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.095238095,"the, analysis, that, is, in, of"
43426,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.095238095,"from, wild, in, the, market, have"
43427,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.095238095,"the, of, in, is, to, from"
43428,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.095238095,"analysis, of, the, that, is, a"
43429,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.095238095,"to, were, sold, live, in, the"
43430,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.095238095,"that, are, the, of, have, in, march, for"
43431,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.095238095,"the, as, a, of, that, likely, from, to"
43432,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.095238095,"we, for, that, in, the, of"
43433,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.095238095,"a, virus, animals, the, it, is"
43434,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.095238095,"the, data, that, is, not, virus"
43435,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.095238095,"we, and, that, in, the, of"
43436,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.095238095,"that, originated, from, a"
43437,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.095238095,"that, to, in, from"
43438,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.095238095,"the, that, was, to, most, is, of, and, cause, sars-cov-2"
43439,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.095238095,"the, was, a, and, to, of"
43440,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.095238095,"at, an, infected, to, multiple, for, the, all, of, other"
43441,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.095238095,"that, has, and, the"
43442,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.095238095,"that, a, bat, to"
43443,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.095238095,"the, from, this, is"
43444,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.095238095,"were, also, that, this"
43445,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.095238095,"a, to, that, of"
43446,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.095238095,"of, to, and, that"
43447,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.095238095,"and, have, that, of"
43448,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.095238095,"and, of, that, a"
43449,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.095238095,"and, that, a, of"
43450,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.095238095,"of, and, that, a"
43451,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.095238095,"that, in, human, and"
43452,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.095238095,"that, all, in, and"
43453,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.095238095,"all, which, have, from"
43454,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.095238095,"to, through, is, and"
43455,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.095238095,"a, bat, genome, the"
43456,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.095238095,"that, the, and, coronavirus"
43457,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.095238095,"the, of, intermediate, host, as, to"
43458,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.095238095,"intermediate, as, to, was, the, of"
43459,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.095238095,"the, in, bats, a"
43460,"the close relation  

between SARS coronavirus and 2019-nCoV","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.095238095,"the, relation"
43461,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.095238095,"the, a, of, with"
43462,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.095238095,"in, with, the, of"
43463,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.095238095,"to, that, in, than"
43464,"Those who eagerly peddle suggestions of 

laboratory involvement have consistently failed to present 

credible arguments to support their positions.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.095238095,"those, who, of, to"
43465,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.095238095,"to, the, been, in, of, that"
43466,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.095238095,"and, sars-cov-2, to, bats"
43467,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.095238095,"that, a, virus, sars-cov-2"
43468,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.095238095,"sars-cov-2, a, and, was"
43469,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.095238095,"the, sars-cov-2, and, pangolin"
43470,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.095238095,"a, of, and, that, the, from"
43471,"Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.095238095,"a, for, and, coronavirus"
43472,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.095238095,"the, and, horseshoe, from, to, respectively"
43473,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.095238095,"the, genome, to, bat"
43474,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Bats have been reported as being the rich source of 

coronaviruses",0.095238095,"as, of, the, being"
43475,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.095238095,"a, the, sars-cov-2, to"
43476,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.095238095,"the, sars-cov-2, to, pangolin"
43477,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.095238095,"from, of, infected, and"
43478,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.095238095,"the, and, similar, to"
43479,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.095238095,"sars-cov-2, with, their, and"
43480,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.095238095,"and, infected, the, of"
43481,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.095238095,"can, the, and, of"
43482,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.095238095,"the, coronavirus, with, bat"
43483,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.095238095,"and, to, of, the"
43484,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.095238095,"and, of, intermediate, pangolin"
43485,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.095238095,"human, and, the, of"
43486,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.095238095,"have, sequences, to, and"
43487,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.095238095,"the, and, to, suggesting, that, have"
43488,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.095238095,"the, is, and, on"
43489,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.095238095,"from, a, and, to, in, the"
43490,hese close genetic relations suggest that they all have their ecological origin in bat populations,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.095238095,"genetic, that, have, in"
43491,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.095238095,"of, covid-19, the, through"
43492,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.095238095,"that, to, the, of"
43493,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.095238095,"of, and, the, in, naturally, bats"
43494,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.095238095,"of, the, in, was, is, to"
43495,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.095238095,"is, was, the, virus, genetic, in"
43496,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.095238095,"the, and, in, bats, is, to"
43497,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.095238095,"is, naturally, of, the"
43498,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.095238095,"they, is, the, of"
43499,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.095238095,"covid-19, has, to, that"
43500,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.095238095,"has, in"
43501,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.095238095,"that, as, at, the, a, of, is, evidence"
43502,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.095238095,"a, at, the, is"
43503,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.095238095,"and, the, that, natural"
43504,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.095238095,"and, that, similar, in"
43505,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.095238095,"and, virus, the, in"
43506,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.095238095,"in, to, the, and"
43507,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.095238095,"and, similar, in, the"
43508,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.095238095,"to, in, and, animal"
43509,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.095238095,"and, with, the, bat"
43510,"Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.095238095,"or, the, reservoir, be"
43511,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.095238095,"to, sars-cov, or, mers-cov"
43512,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.095238095,"host, of, the, bats"
43513,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.095238095,"the, reservoir, or, be"
43514,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.095238095,"the, or, could, be"
43515,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.095238095,"the, wet, animals, infected"
43516,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.095238095,"in, have, the, from, wild, market"
43517,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.095238095,"from, the, wild, animals"
43518,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.095238095,"from, the, may, have, been, in"
43519,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.095238095,"in, the, from, or"
43520,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.095238095,"related, that, the, to"
43521,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.095238095,"to, sars-cov-2, could, bats, the, that"
43522,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.095238095,"the, analysis, that, bats"
43523,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.095238095,"that, bats, the, reservoir"
43524,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.095238095,"be, that, the, bat"
43525,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.095238095,"the, was, in, wuhan"
43526,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.095238095,"virus, that, was, the"
43527,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.095238095,"the, that, virus, it"
43528,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.095238095,"the, of, with, market, that, in"
43529,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.095238095,"of, that, the, a, as, or"
43530,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.095238095,"the, coronavirus, bat, with"
43531,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.095238095,"the, of, novel, coronavirus, that, bat"
43532,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.095238095,"the, that, of, with, genomic, but"
43533,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.095238095,"the, of, identical, sars-cov-2"
43534,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.095238095,"of, the, sars-cov-2, been"
43535,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.095238095,"of, the, to, sars-cov-2"
43536,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.095238095,"of, sars-cov-2, the, to"
43537,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.095238095,"the, was, that, for"
43538,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.095238095,"another, found, of, and, which, to"
43539,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.095238095,"is, bat"
43540,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.095238095,"to, sars-cov"
43541,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.095238095,"and, intermediate, in, human, humans, to"
43542,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","Coronaviruses are naturally hosted and developmentally 

formed by bats.",0.095238095,"are, bats."
43543,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.095238095,"to, the, several, and, of, sequence, that, have, identical, genome"
43544,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.095238095,"sars-cov-2, to, that, may"
43545,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.095238095,"the, of, from, as"
43546,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.095238095,"in, viruses, are, pangolin, the, same"
43547,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.095238095,"the, pangolin, viruses, same"
43548,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.095238095,"that, of, have, by"
43549,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.095238095,"have, that, of, and"
43550,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.095238095,"that, of, is, by"
43551,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.095238095,"that, of, most, bat"
43552,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.095238095,"which, the, in, its"
43553,"bats are also important reservoir species for a great 

range of coronaviruses",Many of these CoVs can infect several animal species as well,0.095238095,"species, of"
43554,"All human coronaviruses have animal origins, namely, natu- 

ral hosts","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.095238095,"human, animal"
43555,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.095238095,"is, an, a, from"
43556,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.095238095,"from, the, virus, humans"
43557,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.095238095,"a, the, it, animals, virus, is"
43558,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.095238095,"from, the, animals, for"
43559,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.095238095,"the, is, for, a, virus, to"
43560,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.095238095,"the, animals, to, a, for, is, time, virus"
43561,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.095238095,"the, it, for, spillover, from, a"
43562,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.095238095,"from, it, to, for, the, a"
43563,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.095238095,"to, when, the, virus"
43564,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.095238095,"a, the, from, for"
43565,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.095238095,"the, from, humans, to, closely, related"
43566,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.095238095,"in, of, to, the, is, from"
43567,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.095238095,"the, of, from, in, sars, to"
43568,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.095238095,"to, the, bats, of"
43569,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.095238095,"also, the, of, to"
43570,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.095238095,"genetic, have, that, in"
43571,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.095238095,"that, in, bat, populations"
43572,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.095238095,"could, have, and, the"
43573,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.095238095,"to, the, may, human"
43574,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.095238095,"from, to, in, an"
43575,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.095238095,"is, that, and, sars-cov-2"
43576,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.095238095,"is, sars-cov-2, and, that"
43577,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.095238095,"in, bats"
43578,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.095238095,"the, that, infected, sars-cov-2"
43579,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.095238095,"that, sars-cov-2, from, the"
43580,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.095238095,"an, intermediate, to, very"
43581,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.095238095,"the, of, and, had"
43582,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.095238095,"coronavirus, and, the, of"
43583,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.095238095,"virus, that, to, the"
43584,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.095238095,"and, to, the, that"
43585,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.095238095,"the, virus, and, in"
43586,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.095238095,"the, virus, with, human"
43587,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.095238095,"virus, in, whole, genome"
43588,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.095238095,"in, the, without, from, and, of"
43589,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.095238095,"analysis, in, the, of, isolated, from"
43590,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.095238095,"the, of, to, with"
43591,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.095238095,"the, that, to, zoonotic"
43592,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.095238095,"in, coronaviruses, are, and, with, for"
43593,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.095238095,"endemic, for, of, and"
43594,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.095238095,"coronaviruses, are, of, common"
43595,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.095238095,"sars-cov, intermediate, as, and, to, the, of, a"
43596,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.095238095,"bat, coronavirus, approximately, the"
43597,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.095238095,"the, bat, and, coronavirus"
43598,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.095238095,"the, of, that, to, from, viruses,"
43599,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.095238095,"of, the, novel, coronavirus, bat, that"
43600,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.095238095,"the, of, that, as, was, to"
43601,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.095238095,"coronavirus, and, very, from, to, close"
43602,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.095238095,"the, of, that, has"
43603,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.095238095,"the, of, virus, and, that, to"
43604,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.095238095,"and, the, of, bat, to, moreover,, that, virus"
43605,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","no modifications were  

recorded for nonstructural proteins NSP7, NSP13  

and the structured and accessory proteins p6 and 8b.",0.095238095,"the, were, for, and"
43606,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.095238095,"identity, with, of, in"
43607,"In the 

case of MERS, dromedaries were the principal host.","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.095238095,"in, of"
43608,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.095238095,"sars-cov-2, from, a, the, and, that"
43609,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.095238095,"a, natural, and, the"
43610,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.095238095,"in, sars-cov-2, to, ("
43611,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.095238095,"that, the, is, bat"
43612,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.095238095,"the, that, at, and"
43613,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.095238095,"ancestral, of, and, genomes"
43614,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.095238095,"of, the, two, and"
43615,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.095238095,"infected, and, the, of"
43616,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.095238095,"who, a, that, was"
43617,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.095238095,"a, at, market, was"
43618,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.095238095,"a, in, china, identified"
43619,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.095238095,"at, was, in, province,"
43620,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.095238095,"genomic, that, are, the"
43621,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.095238095,"the, to, that, are"
43622,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.095238095,"the, of, to, sars-cov"
43623,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.095238095,"in, the, a, from, and, with"
43624,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.095238095,"from, in, the, of, a, sars-cov-2"
43625,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.095238095,"identity, in, with, of"
43626,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.095238095,"in, yunnan, the, bat"
43627,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.095238095,"this, sars-cov-2"
43628,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.095238095,"from, intermediate, hosts, that, for, the"
43629,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.095238095,"analysis, of, the, isolated, from, in"
43630,The COVID-19 most likely developed from bat origin coronaviruses,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.095238095,"the, most, likely, from"
43631,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.095238095,"bat, to, sars-cov-2,, similar, the, genome"
43632,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.095238095,"in, the, of, a, that, to, and, sequence"
43633,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.095238095,"the, of, to, likely"
43634,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.095238095,"bats, to, are, hosts"
43635,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.095238095,"from, animals, for, the"
43636,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Bats are natural hosts of many of the known  

coronaviruses",0.095238095,"coronaviruses, the, of, natural"
43637,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Bats are natural hosts of many of the known  

coronaviruses",0.095238095,"the, are, of, natural"
43638,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.095238095,"as, endemic, to, bat, species, high, and, which"
43639,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.095238095,"in, is, that, be, and, sars-cov-2"
43640,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.095238095,"in, is, to, sars-cov-2, that, which"
43641,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.095238095,"sars-cov-2, from, and, coronaviruses, as, high"
43642,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.095238095,"et, two, of, sequences, and, which"
43643,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.095238095,"the, of, that, was, to, as"
43644,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.095238095,"that, the, of, as, but, to"
43645,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.095238095,"most, to"
43646,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.095238095,"the, similarity, sars-cov-2, which"
43647,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.095238095,"that, the, virus, it"
43648,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.095238095,"the, series, to, of"
43649,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.095238095,"with, the, of, that"
43650,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.095238095,"and, pangolin"
43651,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.095238095,"pangolin, to, and, are"
43652,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.095238095,"to, pangolin"
43653,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.095238095,"on, in, the, and, of, western, huanan, market."
43654,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.095238095,"the, in, and, unknown, seafood, of"
43655,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.095238095,"of, five, patients, at, the, in"
43656,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.095238095,"the, could, be, to"
43657,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.095238095,"that, the, of, after"
43658,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.095238095,"a, of, the, that, analysis, is"
43659,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.095238095,"the, of, a, sars-cov-2"
43660,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.095238095,"a, the, that, sars-cov-2"
43661,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.095238095,"to, is, at, the"
43662,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.095238095,"the, of, bat, a, in, to"
43663,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.095238095,"from, the, bat, ratg13,"
43664,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.095238095,"from, an, was, the"
43665,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.095238095,"the, a, in, to, bat, of"
43666,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.095238095,"the, bat, in, yunnan"
43667,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.095238095,"in, sars-cov-2, closely, related"
43668,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.095238095,"the, of, animal, be"
43669,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.095238095,"pangolin, and"
43670,"a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.095238095,"a, sars-cov-2"
43671,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.095238095,"within, the, and, many"
43672,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.095238095,"a, of, in, the, and, that"
43673,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.095238095,"the, ratg13, and, sars-cov-2"
43674,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.095238095,"of, sars-cov-2, from, the"
43675,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.095238095,"the, of, and, from, a, as"
43676,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.095238095,"and, the, of, sars-cov-2, from, a"
43677,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.095238095,"sars-cov-2, the, origin, of"
43678,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.095238095,"sequence, that, the, of, sars-cov-2, analysis"
43679,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.095238095,"sars-cov-2, to, in, ("
43680,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.095238095,"a, to, the, human"
43681,"zoonotic corona- 

viruses have become an increasing threat to human health,","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.095238095,"zoonotic, human"
43682,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.095238095,"to, the, of, and, have, as"
43683,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.095238095,"found, the, of, a"
43684,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.095238095,"the, of, a, bats"
43685,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.095238095,"bats, are, a, the, of, virus"
43686,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.095238095,"the, coronaviruses, are, china"
43687,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K",0.095238095,"human, in, to, with"
43688,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.095238095,"and, the, zoonotic, of, in, a"
43689,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.095238095,"and, the, of, been, in, a"
43690,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.095238095,"that, were, also, this"
43691,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.095238095,"bats, are, to, hosts"
43692,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.095238095,"also, to, suggesting, that, these, are"
43693,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.095238095,"to, the, of, zoonotic"
43694,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.095238095,"the, from, shares, with"
43695,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.095238095,"again, bats, the, of"
43696,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.095238095,"to, or, sars-cov, mers-cov"
43697,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.095238095,"the, were, in, it"
43698,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.095238095,"the, sars-cov-2, pangolins, in"
43699,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.095238095,"the, sars-cov-2, in, a"
43700,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.095238095,"the, in, were, with"
43701,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.095238095,"genetic, similarity, sars-cov-2, the"
43702,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.095238095,"in, the, intermediate, host, a, were"
43703,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.095238095,"a, as, the, of, be, to"
43704,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.095238095,"a, the, to, human"
43705,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.095238095,"the, human, to, may"
43706,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.095238095,"the, to, most, bat"
43707,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.095238095,"the, to, a, most"
43708,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.095238095,"in, to, the, sars-cov-2"
43709,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.095238095,"in, is, sars-cov-2, the"
43710,"ARS-CoV-2 is a 

natural virus, not a lab-created one.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.095238095,"is, not"
43711,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.095238095,"in, the, of, and, to, for, more, virus"
43712,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.095238095,"of, that, the, is, a, for"
43713,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.095238095,"bats, an, intermediate, the, from, in"
43714,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.095238095,"the, two, from, in"
43715,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.095238095,"that, in, a, genome"
43716,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.095238095,"sars-cov-2, in, with, bat"
43717,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.095238095,"in, with, that, sars-cov-2, of, bat"
43718,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.095238095,"human, virus, with, the"
43719,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.095238095,"with, the, shares, from"
43720,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.095238095,"virus, from, with, the"
43721,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.095238095,"that, is, by, of"
43722,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.095238095,"sars-cov-2, is, the, same"
43723,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.095238095,"and, of, phylogenetic, pangolin-cov"
43724,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.095238095,"has, the, in, of"
43725,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.095238095,"found, sars-cov-2, of, high"
43726,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.095238095,"sars-cov-2, also, in, and, the, as"
43727,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.095238095,"has, in, that,, the, and, to"
43728,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","bats are also important reservoir species for a great 

range of coronaviruses",0.095238095,"of, a, species, for"
43729,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","bats are also important reservoir species for a great 

range of coronaviruses",0.095238095,"a, of, are, for"
43730,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.095238095,"were, in, to, the"
43731,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.095238095,"the, to, sars-cov-2, ace2"
43732,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.095238095,"of, from, in, sars-cov-2"
43733,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.095238095,"ratg13,, the, from, bat"
43734,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.095238095,"the, from, bat, and"
43735,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.095238095,"of, at, the, et"
43736,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.095238095,"the, to, from, and, horseshoe, respectively"
43737,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.095238095,"in, to, is, the, bats, and"
43738,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.095238095,"by, one, similar, to, and, the"
43739,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.095238095,"in, the, a, human"
43740,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.095238095,"the, human, in, to"
43741,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.095238095,"the, to, for, a"
43742,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.095238095,"the, in, with, sars-cov-2"
43743,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.095238095,"the, same, in, with"
43744,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.095238095,"sars-cov-2, is, natural, that, to, the"
43745,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.095238095,"the, of, and, that, sars-cov-2, animal"
43746,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.095238095,"in, the, sars-cov-2, also, and, as"
43747,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.095238095,"of, and, a, species, in, the"
43748,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.095238095,"that, the, in, and, to, humans"
43749,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.095238095,"the, and, have, suggesting, that, to"
43750,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.095238095,"that,, in, to, the, has, and"
43751,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.095238095,"to, in, through, mice, and, these"
43752,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.095238095,"a, to, reported, and, the, in"
43753,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.095238095,"a, study, in, sars-cov-2"
43754,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.095238095,"a, to, the, sars-cov-2"
43755,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.095238095,"could, be, to, the"
43756,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.095238095,"ace2, to, sars-cov-2, the"
43757,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.095238095,"sars-cov-2, to, a, the"
43758,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.095238095,"is, and, to, through"
43759,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.095238095,"is, also, the, of"
43760,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.095238095,"very, to, an, intermediate"
43761,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.095238095,"the, and, a, to, that, of"
43762,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.095238095,"of, known, to, the"
43763,"In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.095238095,"in, to, with, human"
43764,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.095238095,"in, to, the, were, sold, live"
43765,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.095238095,"the, and, were, species, in, to"
43766,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.095238095,"the, conditions, live, to, in, were, animal, and"
43767,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.095238095,"in, the, sars-cov-2, animal"
43768,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.095238095,"the, that, host, of"
43769,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.095238095,"of, samples, from, in"
43770,"atural  

selection in an animal host before zoonotic  

transfer;","Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan",0.095238095,"in, animal"
43771,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",Wet Market animals maintained in poor conditions,0.095238095,"in, animals"
43772,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.095238095,"that, the, in, of"
43773,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.095238095,"that, sars-cov-2, to, bats, could, the"
43774,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.095238095,"evidence, in, the, and, that, of, to, from"
43775,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.095238095,"the, of, which, natural"
43776,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.095238095,"the, of, covid-19, in"
43777,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.095238095,"one, of, the, systems"
43778,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.095238095,"the, species, in, china"
43779,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Bats are the second  

largest order of mammals, with over 1,230 species.",0.095238095,"of, with, are, the"
43780,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.095238095,"and, bat, species, as, high, to, which, endemic"
43781,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",Coronaviruses account for over 30% of the world’s viruses.,0.095238095,"coronaviruses, the, for, of"
43782,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.095238095,"as, for, and, the"
43783,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.095238095,"of, endemic, and, for"
43784,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.095238095,"are, the, and, in, that, to"
43785,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.095238095,"all, that, in, and"
43786,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.095238095,"are, the, china, coronaviruses"
43787,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.095238095,"to, the, most, bat"
43788,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.095238095,"the, related, to, most"
43789,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.095238095,"the, and, for, to"
43790,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.095238095,"the, and, virus, to"
43791,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.095238095,"in, related, and, to"
43792,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.095238095,"an, and, the, in"
43793,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.095238095,"of, to, bat, in"
43794,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.095238095,"in, bat, similar, and"
43795,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.095238095,"the, similar, and, in"
43796,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.095238095,"in, a, of, species, and, the"
43797,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.095238095,"this, are, the, of"
43798,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.095238095,"the, of, that, as, but, to"
43799,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.095238095,"in, the, of, that, its, as, a, bats"
43800,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.095238095,"a, is, the, to, that, in, virus, and"
43801,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.095238095,"moreover,, and, that, the, virus, to, of, bat"
43802,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.095238095,"a, virus, that, with, the, in, its, bat"
43803,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.095238095,"the, related, to, for, which, a, is, also"
43804,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.095238095,"the, that, with, of, virus, and, less, to"
43805,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.095238095,"of, sars-cov-2, to, a"
43806,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.095238095,"all, have, which, from"
43807,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.095238095,"to, which, a, from"
43808,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.095238095,"the, coronavirus, approximately, bat"
43809,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.095238095,"the, genome, bat, similar, to, sars-cov-2,"
43810,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.095238095,"is, to, at, the"
43811,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.095238095,"sars-cov-2, genetic, similarity, the"
43812,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.095238095,"the, is, by, bat"
43813,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.095238095,"the, sars-cov-2, highest, by"
43814,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.095238095,"similar, to, sars-cov-2, the"
43815,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.095238095,"the, with, and, sars-cov-2, at, in"
43816,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.095238095,"are, the, sars-cov-2, to, by, with, in, and"
43817,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.095238095,"are, the, of, by"
43818,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.095238095,"the, to, series, of"
43819,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.095238095,"the, by, to, sars-cov-2, of, are"
43820,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.095238095,"the, to, a, of, genetic, is, found, in"
43821,"zoonotic corona- 

viruses have become an increasing threat to human health,",all three BANAL series viruses also use ACE2 as an entry receptor.,0.095238095,"viruses, an"
43822,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.095238095,"the, to, through, of"
43823,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.095238095,"the, of, that, to, human, than"
43824,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.095238095,"the, experiments, that, to"
43825,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","This suggests that the BANAL series may be able to directly infect  

humans.",0.095238095,"to, the, that, be"
43826,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.095238095,"to, than, in, that"
43827,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.095238095,"to, viruses, that, in"
43828,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.095238095,"2, from, of, the"
43829,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.095238095,"he, of, from, the"
43830,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.095238095,"the, of, is, also"
43831,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.095238095,"the, have, of, viruses"
43832,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.095238095,"is, at, the, a"
43833,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.095238095,"is, the, and, to"
43834,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.095238095,"viruses, to, the, have, and, a"
43835,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.095238095,"a, the, is, and"
43836,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.095238095,"in, and, to, these, mice, through"
43837,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.095238095,"the, viruses,, genetic, to"
43838,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.095238095,"related, the, closely, to"
43839,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.095238095,"in, bats, and, was"
43840,"t some virus detected in pangolins 

were capable of infecting humans.","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.095238095,"t, in"
43841,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.095238095,"in, to, the, virus, covid-19, is"
43842,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.095238095,"to, with, the, and, may, bat"
43843,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.095238095,"in, the, and, are, to, other, there, more"
43844,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.095238095,"the, a, to, with, and, bat"
43845,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.095238095,"bat, to, sars-cov-2, than"
43846,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.095238095,"sars-cov-2, is, and, be, that, in"
43847,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.095238095,"the, is, that, in, identified, case, and, covid-19"
43848,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.095238095,"be, the, sars-cov-2, and"
43849,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.095238095,"a, was, the, of, and, to"
43850,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.095238095,"the, of, sars, in, to, from"
43851,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.095238095,"species, to, were, and, in, the"
43852,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.095238095,"from, an, animal, reservoir, host, to, a, as, studies, and, found, in"
43853,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.095238095,"of, to, human, a, virus, that, in, an, and, the"
43854,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.095238095,"from, humans, to, closely, related, the"
43855,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.095238095,"the, of, and, that, a, sequence, in, to"
43856,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.095238095,"were, a, intermediate, host, the, in"
43857,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.095238095,"that, the, of, to, human, than"
43858,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.095238095,"a, virus, from, to, of, and, more, as"
43859,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.095238095,"from, an, as, was, the, more"
43860,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.095238095,"several, have, the, and, of, genome, sequence, identical, to, that"
43861,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.095238095,"sampled, from, a, identical, overall, to, in, the, that, not"
43862,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.095238095,"one, of, more, than, and, bats, for, virus, were, coronavirus"
43863,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.095238095,"in, the, of, and, at, to, viruses, for, other, more, virus, had"
43864,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.095238095,"the, as, a, species, of, that, likely, from, to, by, bat, and"
43865,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.095238095,"to, an, for, the, multiple, of, infected, at, all, other"
43866,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.095238095,"a, virus, animals, to, for, the, time, is"
43867,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.095238095,"animal, to, were, live, and, in, conditions, the"
43868,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.095238095,"on, from, early, in, wuhan, the, of, and"
43869,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.095238095,"wuhan, the, in, of, only, and, had, before"
43870,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.095238095,"2, that, to, experts, the, had, an, by, a, of, is, for"
43871,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.095238095,"in, is, that, the, covid-19, case, identified, and"
43872,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.095238095,"a, reported, the, to, and, in"
43873,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.095238095,"other, to, and, a, the, of"
43874,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.095238095,"the, of, huanan, and, in, collected"
43875,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.095238095,"is, the, to, a"
43876,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.095238095,"natural, of, and, a, to, zoonotic"
43877,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.095238095,"the, sars, are, in"
43878,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.095238095,"live, are, in, to"
43879,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.095238095,"of, the, genomic, with, that, but"
43880,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.095238095,"collected, and, of, in, the, huanan"
43881,"unnatural origin of SARS-CoV-2, but these people are 

simply wrong","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.095238095,"of, but, these, are"
43882,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.095238095,"these, are, the, in, and, that"
43883,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.095238095,"a, from, for, the, it, spillover"
43884,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.095238095,"the, a, of, that, likely, from, by, and"
43885,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.095238095,"evidence, to, the, that, of, from"
43886,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.095238095,"in, that, the, to, huanan, market"
43887,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.095238095,"and, of, the, huanan, market, in"
43888,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.095238095,"evidence, to, from, of, in, the, and, that"
43889,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.095238095,"that, the, virus, to"
43890,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.095238095,"the, to, that, sars-cov-2, is, natural"
43891,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Those who eagerly peddle suggestions of 

laboratory involvement have consistently failed to present 

credible arguments to support their positions.",0.095238095,"of, to, those, who"
43892,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","expended to make the simple point 

that COVID-19 had a natural origin.",0.095238095,"that, the, covid-19, a"
43893,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","expended to make the simple point 

that COVID-19 had a natural origin.",0.095238095,"that, a, to, the"
43894,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","unnatural origin of SARS-CoV-2, but these people are 

simply wrong",0.095238095,"of, are, these, but"
43895,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","unnatural origin of SARS-CoV-2, but these people are 

simply wrong",0.095238095,"origin, of"
43896,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.095238095,"were, from, bats, and"
43897,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.095238095,"in, related, that, to"
43898,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.095238095,"that, in, from, to"
43899,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.095238095,"sars-cov-2, to, in, and"
43900,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.095238095,"that, bats, including, and"
43901,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.095238095,"sars-cov-2, and, coronaviruses, to"
43902,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.095238095,"hypothesis, lab, the, from"
43903,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.095238095,"and, sars-cov-2, in, a"
43904,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.095238095,"following, in, a, humans"
43905,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.095238095,"has, and, sars-cov-2, a"
43906,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.095238095,"sars-cov-2, in, host, or"
43907,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.095238095,"a, the, virus, in, with, that"
43908,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.095238095,"the, bat, a, with, that, in, virus, its"
43909,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.095238095,"the, bat, that, its"
43910,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.095238095,"the, sequence, identity, in"
43911,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.095238095,"the, identity, that, sars-cov-2"
43912,The FCS of SARS-CoV-2 was not bioengineered—full stop.,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.095238095,"sars-cov-2, not"
43913,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.095238095,"the, one, of, systems"
43914,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.095238095,"the, data, virus, that, not, is"
43915,"Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan","atural  

selection in an animal host before zoonotic  

transfer;",0.095238095,"animal, in"
43916,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.095238095,"the, to, that, bat"
43917,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.095238095,"that, the, its, bat"
43918,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.095238095,"to, the, not, a, in, sampled, from, that, identical, overall"
43919,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.095238095,"is, that, rhinolophus, the"
43920,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Malayan pangolins (Manis javanica)  

illegally imported into Guangdong province  

contain coronaviruses similar to SARS- 

CoV-22",0.095238095,"pangolins, guangdong, province, similar"
43921,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.095238095,"in, of, for, sars-cov-2, to, that"
43922,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.095238095,"that, a, of, by"
43923,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.095238095,"of, natural, the, and, cleavage, site"
43924,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.095238095,"the, of, through, that"
43925,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.095238095,"t, that, of, sars-cov-2"
43926,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.095238095,"that, pangolins, the, sars-cov-2"
43927,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.095238095,"the, of, sars-cov-2, identical"
43928,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.095238095,"in, the, that, coronaviruses, any, and"
43929,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.095238095,"in, the, including, and, of, sars-cov-2"
43930,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.095238095,"the, that, scenario, of, sars-cov-2, is"
43931,"Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan","In the 

case of MERS, dromedaries were the principal host.",0.095238095,"of, in"
43932,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.095238095,"have, been, from, to, and, in"
43933,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.095238095,"coronavirus, from, very, close, to, and"
43934,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.095238095,"but, a, bat, to, not, and"
43935,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.095238095,"of, the, covid-19, that"
43936,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.095238095,"that, most, of, bat"
43937,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.095238095,"after, of, the, that"
43938,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.095238095,"in, a, the, nature"
43939,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.095238095,"animal, coronavirus, in, the"
43940,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.095238095,"provides, the, evidence, that"
43941,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.095238095,"additional, that, the, a"
43942,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.095238095,"bats, the, of, and, in, to"
43943,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.095238095,"sequence, identity, the, in"
43944,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.095238095,"to, that, the, from"
43945,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.095238095,"and, the, which, that"
43946,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.095238095,"that, to, and, the"
43947,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",The COVID-19 most likely developed from bat origin coronaviruses,0.095238095,"bat, the"
43948,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",The COVID-19 most likely developed from bat origin coronaviruses,0.095238095,"the, from, most, likely"
43949,"Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",The COVID-19 most likely developed from bat origin coronaviruses,0.095238095,"from, the"
43950,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.095238095,"a, of, that, the, or, from"
43951,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.095238095,"that, the, or, as, a, of"
43952,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.095238095,"the, of, for, is, that, a"
43953,"bats are also important reservoir species for a great 

range of coronaviruses","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.095238095,"species, for, a, of"
43954,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.095238095,"a, of, receptor, is, the, for"
43955,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.095238095,"in, the, of, and, unknown, seafood"
43956,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.095238095,"in, the, originated, and"
43957,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.095238095,"of, are, coronaviruses, common"
43958,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.095238095,"in, covs, and, to"
43959,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.095238095,"in, to, be, that"
43960,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.095238095,"through, in, to, humans"
43961,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.095238095,"been, the, in, of"
43962,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.095238095,"been, the, in, of, and, china"
43963,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.095238095,"of, to, the, in, that, been"
43964,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.095238095,"viruses, to, and, have, a, the"
43965,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.095238095,"in, march, of, have, the, are, that, for"
43966,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.095238095,"reservoir, and, for, the, of, that, have, in"
43967,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.095238095,"the, in, province,, wuhan"
43968,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.095238095,"were, two, of, in"
43969,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.095238095,"the, in, two, market"
43970,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.095238095,"of, the, covid-19, with"
43971,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.095238095,"the, covid-19, of, in"
43972,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.095238095,"the, has, been, of, that, to"
43973,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.095238095,"the, have, not, been"
43974,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.095238095,"rhinolophus, is, the, that"
43975,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.095238095,"the, from, in, is"
43976,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.095238095,"bat, by, is, the"
43977,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.095238095,"the, from, all, bat"
43978,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.095238095,"from, rhinolophus, bat, in"
43979,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.095238095,"bats, the, host, of"
43980,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.095238095,"body, of, and, or, in, bats"
43981,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.095238095,"from, is, to, the"
43982,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.095238095,"bats, species, by, and"
43983,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.095238095,"in, related, the, closely"
43984,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.095238095,"previous, bats, the, and"
43985,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.095238095,"of, as, a, virus, from, to, and, more"
43986,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.095238095,"to, bat, and, a, but, not"
43987,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.095238095,"to, be, virus, bats"
43988,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.095238095,"or, to, virus, in"
43989,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.095238095,"in, recently, to, be, bats, are"
43990,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.095238095,"the, has, been, to, bats, in, of, be"
43991,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.095238095,"a, was, the, and"
43992,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.095238095,"the, of, sars-cov-2, been"
43993,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.095238095,"the, virus, from, with"
43994,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.095238095,"xiao, et, al., by, and, for"
43995,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.095238095,"were, of, which, in"
43996,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.095238095,"pangolins, intermediate, the, in"
43997,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.095238095,"from, bats, an, intermediate, in, the"
43998,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.095238095,"and, an, in, the"
43999,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.095238095,"this, of, the, that"
44000,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.095238095,"and, a, the, is"
44001,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.095238095,"is, a, that, the"
44002,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.095238095,"also, a, for, the, is, to"
44003,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.095238095,"a, is, the, to"
44004,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.095238095,"to, the, most, a"
44005,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.095238095,"the, to, most, related"
44006,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.095238095,"the, also, to, a, related, for, which, is"
44007,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.095238095,"to, which, from, a"
44008,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.095238095,"the, from, to, a, also, and"
44009,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.095238095,"a, of, to, the, likely, that, from, as"
44010,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.095238095,"the, of, a, to, bat, as, by, and, that, likely, from, species"
44011,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.095238095,"and, the, likely, that, of, from, a, by"
44012,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.095238095,"the, to, that, has, been, of"
44013,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.095238095,"sars-cov-2, sequence, identity, with"
44014,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.095238095,"and, the, from, to, a, in"
44015,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.095238095,"on, the, and, is"
44016,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.095238095,"in, is, the, on"
44017,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.095238095,"virus, the, that, sars-cov-2"
44018,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.095238095,"the, of, is, a, virus, that"
44019,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","zoonotic corona- 

viruses have become an increasing threat to human health,",0.095238095,"human, zoonotic"
44020,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","zoonotic corona- 

viruses have become an increasing threat to human health,",0.095238095,"an, viruses, to, human"
44021,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.095238095,"for, the, of, and, virus, to"
44022,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.095238095,"to, the, virus, of"
44023,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.095238095,"on, origin, of, based"
44024,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.095238095,"the, in, animal, coronavirus"
44025,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.095238095,"a, in, that, to, an, host"
44026,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.095238095,"a, to, that, in"
44027,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.095238095,"a, that, bat, to"
44028,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.095238095,"from, an, in, to"
44029,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.095238095,"to, from, a, sars-cov-2"
44030,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.095238095,"to, bat, it, that"
44031,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.095238095,"the, with, that, of"
44032,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.095238095,"that, not, the, of"
44033,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.095238095,"the, has, that, of"
44034,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.095238095,"sars-cov-2, a, that, the"
44035,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.095238095,"that, the, of, yet"
44036,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.095238095,"the, reservoir, not, of"
44037,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.095238095,"the, not, have, been"
44038,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.095238095,"the, sars-cov-2, and, have, to, a, of, in"
44039,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.095238095,"from, in, the, may, have, been"
44040,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.095238095,"a, from, to, for, the, it"
44041,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.095238095,"sars-cov, and, a, to, the, of, as, intermediate"
44042,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.095238095,"that, the, reservoir, of, and, have, in, for"
44043,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.095238095,"the, of, sars-cov-2, and, to, sars-cov"
44044,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.095238095,"the, animal, likely, zoonotic"
44045,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.095238095,"the, was, from, an"
44046,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.095238095,"the, as, an, was, from, more"
44047,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.095238095,"been, in, sars-cov-2, has"
44048,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.095238095,"the, likely, that, and"
44049,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.095238095,"of, natural, the, and, virus, genetic"
44050,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",Genetic evidence suggesting otherwise is yet to be presented.,0.095238095,"is, evidence"
44051,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.095238095,"sars-cov-2, the, that, of, scenario, is"
44052,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.095238095,"hypothesis, is, the, that, an, scenario"
44053,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.095238095,"of, the, and, a"
44054,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.095238095,"in, the, of, sars-cov-2, have, to"
44055,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.095238095,"has, been, sars-cov-2, in"
44056,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.095238095,"is, from, an, a"
44057,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.095238095,"to, ratg13, and, identity"
44058,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",SARS-CoV-2 was created from SARS-CoV-2,0.095238095,"from, was"
44059,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",SARS-CoV-2 was created from SARS-CoV-2,0.095238095,"was, sars-cov-2"
44060,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.095238095,"sars-cov-2, that, to, from"
44061,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.095238095,"on, sequences, in, of, based, and"
44062,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.095238095,"in, of, to, sars-cov-2, that, which"
44063,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.095238095,"similarity, sars-cov-2, bat, ratg13"
44064,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.095238095,"genome, bat, of, these"
44065,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.095238095,"the, that, provides, evidence"
44066,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.095238095,"that, has, been, identified, and, to"
44067,"Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.095238095,"from, the, lab, hypothesis"
44068,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.095238095,"the, that, scenario, is, an, hypothesis"
44069,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.095238095,"similarity, sars-cov-2, to, the"
44070,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.095238095,"of, sars-cov-2, bat, and"
44071,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.095238095,"bat, of, sars-cov-2, sequences"
44072,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.095238095,"the, animals, in, to"
44073,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.095238095,"in, by, with, and, are, to, sars-cov-2, the"
44074,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.095238095,"and, holmes, of, sars-cov-2, in, the, genomes, to"
44075,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.095238095,"of, yet, that, the"
44076,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.095238095,"the, pangolins, that, sars-cov-2"
44077,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.095238095,"results, the, that, sars-cov-2"
44078,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.095238095,"from, the, bat, and"
44079,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.095238095,"experiments, that, the, to"
44080,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.095238095,"the, bat, all, from"
44081,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.095238095,"a, also, and, the, to, from"
44082,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.095238095,"analysis, that, bats, the"
44083,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.095238095,"the, is, a, to"
44084,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.095238095,"the, genome, bat, a"
44085,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.095238095,"in, the, of, five, patients, at"
44086,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.095238095,"sars-cov-2, a, of, sequences, in, the"
44087,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.095238095,"sequences, of, sars-cov-2, bat"
44088,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.095238095,"the, by, of, in, (2020), a"
44089,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.095238095,"in, the, of, bat"
44090,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.095238095,"bat, to, in, of"
44091,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.095238095,"bat, from, rhinolophus, in"
44092,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.095238095,"a, in, to, these, bat, of"
44093,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.095238095,"to, the, of, and, which, human"
44094,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.095238095,"of, the, is, a, receptor, for"
44095,"zoonotic corona- 

viruses have become an increasing threat to human health,","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.095238095,"viruses, an, to, human"
44096,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.095238095,"holmes, the, sars-cov-2, genomes, to, in, of, and"
44097,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.095238095,"ratg13, is, to, sars-cov-2"
44098,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.095238095,"found, to, which, of, another, and"
44099,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.095238095,"sequences, of, and, two, which, et"
44100,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.095238095,"and, related, to, in"
44101,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.095238095,"study, small, in, sars-cov-2"
44102,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.095238095,"a, of, and, that, the, pangolins"
44103,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.095238095,"that, sars-cov-2, a, by, the, virus"
44104,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.095238095,"pangolin, and, are, to"
44105,"bats are also important reservoir species for a great 

range of coronaviruses","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.095238095,"are, for, a, of"
44106,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.095238095,"the, and, similar, one, to, by"
44107,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.095238095,"and, by, et, al., xiao, for"
44108,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.095238095,"(2020), a, of, by, the, in"
44109,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.095238095,"have, the, to, as"
44110,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.095238095,"that, sars-cov-2, with, the"
44111,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.095238095,"of, with, a, and, the, in"
44112,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.095238095,"results, that, the, sars-cov-2"
44113,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.095238095,"a, of, in, sars-cov-2"
44114,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.095238095,"pangolin, to"
44115,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.095238095,"than, is, to, sars-cov-2"
44116,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.095238095,"to, sars-cov-2, than, bat"
44117,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.095238095,"sars-cov-2, ratg13, is, to"
44118,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.095238095,"sars-cov-2, is"
44119,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.095238095,"is, sars-cov-2"
44120,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.095238095,"is, of, the, naturally"
44121,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.095238095,"of, that, the, is"
44122,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.095238095,"that, of, the, sars-cov-2"
44123,"Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.095238095,"or, the, could, be"
44124,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.095238095,"the, that, are, and, these, in"
44125,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.095238095,"that, in, bats, or"
44126,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.095238095,"this, and, of, the"
44127,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.095238095,"the, coronavirus, and, that"
44128,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.095238095,"of, viruses, and, the"
44129,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.095238095,"and, the, to, that, sars-cov-2, is"
44130,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.095238095,"to, that, viruses, in"
44131,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.095238095,"bat, similarity, sars-cov-2, ratg13"
44132,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.095238095,"the, similarity, sars-cov-2, to"
44133,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.095238095,"the, are, same, in, viruses, pangolin"
44134,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.095238095,"sars-cov-2, in, to, which"
44135,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.095238095,"bat, in, with, sars-cov-2"
44136,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.095238095,"the, sars-cov-2, is, same"
44137,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.095238095,"that, bat, in, of, with, sars-cov-2"
44138,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.095238095,"that, in, pangolin, and, the, of"
44139,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.095238095,"in, more, the, than"
44140,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.095238095,"are, the, bats, in"
44141,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.095238095,"the, which, similarity, sars-cov-2"
44142,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.095238095,"sars-cov-2, that, with, the"
44143,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.095238095,"suggest, the, bat, origin"
44144,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.095238095,"the, sars-cov-2, that, cov"
44145,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.095238095,"the, of, bats, again"
44146,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.095238095,"this, of, are, the"
44147,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.095238095,"and, sars-cov-2, bat, pangolin"
44148,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.095238095,"sars-cov-2, and, the, pangolin"
44149,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.095238095,"the, and, of, origin"
44150,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.095238095,"the, of, this, sars-cov-2"
44151,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.095238095,"the, same, viruses, pangolin"
44152,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.095238095,"the, and, have, are, origin, sars-cov-2"
44153,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.095238095,"in, that, bats, or"
44154,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.095238095,"have, the, of, to, and, as"
44155,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.095238095,"and, have, the, origin, are, sars-cov-2"
44156,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.095238095,"the, virus, of, and"
44157,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.095238095,"and, from, wuhan, the, in, early, of, on"
44158,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.095238095,"origin, of, based, on"
44159,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.095238095,"in, of, based, on, and, sequences"
44160,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.095238095,"of, these, bat, genome"
44161,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.095238095,"suggest, the, origin, bat"
44162,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.095238095,"of, a, to, other, and, the"
44163,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.095238095,"that, pangolin, the, of"
44164,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.095238095,"and, sars-cov-2, with, similarity"
44165,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.095238095,"the, to, with, of"
44166,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.095238095,"sars-cov, and, to, the, of, sars-cov-2"
44167,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.095238095,"with, the, of, to"
44168,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.095238095,"by, highest, sars-cov-2, the"
44169,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.095238095,"in, of, the, we, that, for"
44170,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.095238095,"the, of, and, in, we, that"
44171,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.095238095,"the, originated, in, and"
44172,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.095238095,"bats, and, previous, the"
44173,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.095238095,"sars-cov-2, similarity, and, with"
44174,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.095238095,"of, the, this, that, and, in"
44175,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.095238095,"in, the, and, that, of, pangolin"
44176,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.095238095,"the, of, that, pangolin"
44177,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.095238095,"and, in, that, the, of, natural"
44178,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.095238095,"that, the, and, at"
44179,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.095238095,"and, the, of, to, with, that, virus, less"
44180,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.095238095,"that, bat, be, the"
44181,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.095238095,"in, the, and, that, of, between"
44182,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.095238095,"an, and, in, the"
44183,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.095238095,"that, identity, the, sars-cov-2"
44184,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.095238095,"sars-cov-2, is, to, which, that, in"
44185,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.095238095,"in, which, to, that, of, sars-cov-2"
44186,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.095238095,"that, sars-cov-2, the, cov"
44187,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.095238095,"sars-cov-2, this"
44188,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.095238095,"the, sars-cov-2, to, be, of, recombination"
44189,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.095238095,"when, virus, to, the"
44190,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.095238095,"phylogenetic, of, pangolin-cov, and"
44191,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.095238095,"the, to, of, transmission"
44192,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.095238095,"with, a, of, the"
44193,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.095238095,"with, a, from, zoonotic"
44194,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.095238095,"the, origin, that, animal"
44195,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.095238095,"was, that, the, for"
44196,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.095238095,"such, to, sars-cov-2, is"
44197,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.095238095,"sars-cov-2, to, be, that"
44198,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.095238095,"they, is, of, the"
44199,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.095238095,"sars-cov-2, and, bat, the"
44200,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.095238095,"the, bat, of, and"
44201,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.095238095,"the, sars-cov-2, be, a, in, human"
44202,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.095238095,"a, from, for, the"
44203,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.095238095,"animal, sars-cov-2, in, the"
44204,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.095238095,"close, of, sars-cov-2, from"
44205,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.095238095,"identified, in, a, china"
44206,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.095238095,"in, from, of, sars-cov-2"
44207,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.095238095,"of, in, samples, from"
44208,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.095238095,"study, sars-cov-2, in, small"
44209,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.095238095,"of, in, sars-cov-2, a"
44210,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.095238095,"a, origin, the, and, are, zoonotic"
44211,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.095238095,"that, may, to, sars-cov-2"
44212,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.095238095,"to, sars-cov-2, in, that, for, of"
44213,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.095238095,"that, to, be, in"
44214,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",evidence suggests bats as its origin,0.095238095,"origin, as"
44215,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.095238095,"and, of, a, natural, zoonotic, to"
44216,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.095238095,"was, in, at, province,"
44217,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.095238095,"the, in, was, at"
44218,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.095238095,"the, closest, sars-cov-2,, in"
44219,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.095238095,"to, similar, sars-cov-2, the"
44220,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.095238095,"in, the, of, was, that, to"
44221,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.095238095,"recently, bats, are, in, to, be"
44222,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.095238095,"that, natural, in, and, the, of"
44223,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.095238095,"in, to, the, than"
44224,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.095238095,"its, the, to, in"
44225,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.095238095,"in, the, closest, sars-cov-2,"
44226,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.095238095,"of, these, to, a, bat, in"
44227,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.095238095,"sars-cov-2, and, coronaviruses, from, as, high"
44228,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.095238095,"found, high, of, sars-cov-2"
44229,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.095238095,"the, that, protein, of"
44230,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.095238095,"and, the, of, cleavage, site, natural"
44231,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.095238095,"genetic, and, natural, of, the, virus"
44232,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.095238095,"coronaviruses, to, sars-cov-2, and"
44233,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.095238095,"the, sars-cov-2, is, that"
44234,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.095238095,"the, that, a, additional"
44235,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.094890511,"at, an, had, to, a, as, animal, for, the, by, otherwise, one, of"
44236,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.094890511,"or, bats, the, be, several, species, of, known, to, as, and, in, isolated"
44237,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.094890511,"to, one, as, at, the, had, an, animal, by, a, of, otherwise, for"
44238,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.094890511,"to, the, bats, as, several, known, be, and, in, of, species, isolated, or"
44239,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.094827586,"a, the, market, studies, and, live, in, to, spread, that, from"
44240,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.094827586,"to, the, and, a, in, of, sequence, that, coronaviruses, genome, overall"
44241,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.094827586,"studies, that, the, from, a, market, live, in, to, and, spread"
44242,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.094827586,"the, genome, of, and, coronaviruses, that, a, sequence, in, overall, to"
44243,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.094827586,"of, the, and, viruses, with, discovery, similar, to, in, virus, ace2"
44244,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.094827586,"and, the, likely, that, supply, was, for, of, in, a, by"
44245,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.094827586,"the, in, a, for, of, likely, was, that, by, and, supply"
44246,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.094827586,"the, discovery, of, viruses, in, to, with, and, virus, similar, ace2"
44247,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.094736842,"and, the, of, a, bats, new, infect, that, in"
44248,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.094736842,"to, the, bats, known, be, and, reservoir, of, species"
44249,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.094736842,"the, of, infected, to, as, a, with, in, is"
44250,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.094736842,"in, a, to, the, discovered, and, had, similarity, virus"
44251,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.094736842,"this, suggested, that, zoonotic, the, animal, of, in, to"
44252,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.094736842,"sars-cov-2, and, of, the, to, with, sars-cov, that, bat"
44253,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.094736842,"the, public, of, from, that, as, to, a, evidence"
44254,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.094736842,"the, huanan, and, of, to, that, sars-cov-2, be, market"
44255,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.094736842,"in, the, that, two, market, to, a, closely, related"
44256,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.094736842,"cases, the, huanan, a, to, that, in, more, market"
44257,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.094736842,"a, is, to, its, the, that, it, bind, human"
44258,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.094736842,"the, of, on, is, in, found, a, virus, that"
44259,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.094736842,"and, environmental, at, the, it, that, of, in, a"
44260,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.094736842,"and, raccoon, it, not, the, of, that, in, a"
44261,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.094736842,"a, to, the, coronavirus, bat, and, 95%, similarity, virus"
44262,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.094736842,"the, of, that, virus, to, data, by, a, and"
44263,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.094736842,"from, the, was, to, a, virus, and, in, its"
44264,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.094736842,"a, january, on, and, were, to, of, the, huanan"
44265,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.094736842,"the, of, infected, where, as, a, with, that, in"
44266,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.094736842,"the, of, sars-cov-2, with, that, sars-cov, and, to, bat"
44267,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.094736842,"to, the, and, coronaviruses., in, of, species, sars-related, an"
44268,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.094736842,"a, of, and, that, the, new, in, infect, bats"
44269,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.094736842,"as, a, of, the, in, is, to, infected, with"
44270,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.094736842,"that, the, infected, with, in, where, as, a, of"
44271,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.094736842,"can, of, and, flight, the, in, bats, viruses, bat"
44272,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.094736842,"a, the, of, in, on, found, virus, that, is"
44273,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.094736842,"the, likely, that, location, for, of, in, a, by"
44274,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.094736842,"reservoir, to, for, by, the, of, that, in, a"
44275,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.094736842,"that, the, suggesting, these, by, associated, with, of, and"
44276,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.094736842,"the, of, that, to, animal, in, suggested, this, zoonotic"
44277,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.094736842,"evidence, to, the, public, that, as, a, of, from"
44278,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.094736842,"in, a, related, that, the, two, closely, to, market"
44279,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.094736842,"a, of, data, to, that, by, the, and, virus"
44280,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.094736842,"bats, of, and, species, known, to, be, the, reservoir"
44281,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.094736842,"and, species, to, an, in, the, of, sars-related, coronaviruses."
44282,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.094736842,"of, virus, that, it, similar, to, the, and, for"
44283,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.094736842,"a, the, to, discovered, in, had, similarity, virus, and"
44284,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.094736842,"the, virus, a, coronavirus, 95%, bat, and, similarity, to"
44285,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.094736842,"wiv, discovered, a, virus, the, in, bat, samples, collected"
44286,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.094736842,"its, and, the, virus, was, from, to, a, in"
44287,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.094736842,"the, huanan, market, that, to, be, sars-cov-2, and, of"
44288,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.094736842,"in, a, that, the, cases, more, to, huanan, market"
44289,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.094736842,"a, the, huanan, on, and, january, of, were, to"
44290,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.094736842,"a, at, the, of, and, environmental, in, it, that"
44291,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.094736842,"the, of, location, by, for, likely, in, a, that"
44292,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.094736842,"in, a, wiv, the, collected, samples, bat, discovered, virus"
44293,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.094736842,"its, that, it, bind, to, human, the, a, is"
44294,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.094736842,"the, of, to, that, and, virus, similar, it, for"
44295,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.094736842,"flight, and, the, of, bat, viruses, bats, in, can"
44296,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.094736842,"a, the, of, and, in, it, raccoon, that, not"
44297,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.094736842,"the, of, by, for, reservoir, in, a, to, that"
44298,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.094736842,"by, of, the, that, and, these, associated, with, suggesting"
44299,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.094594595,"bats, a, the, of, and, in, that"
44300,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.094594595,"the, origin, and, which, a, that, in"
44301,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.094594595,"to, the, have, in, of, and, a"
44302,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.094594595,"also, a, the, is, virus, in, that"
44303,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.094594595,"to, the, virus, that, covid-19, was, same"
44304,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.094594595,"the, and, that, virus, sequence, human, to"
44305,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.094594595,"is, also, that, a, the, virus, in"
44306,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.094594595,"that, the, with, in, as, a, of"
44307,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.094594595,"in, a, with, and, are, to, the"
44308,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.094594595,"can, host, of, and, the, in, bats"
44309,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.094594595,"and, from, to, that, the, natural, hosts"
44310,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.094594595,"the, in, and, that, novel, coronavirus, a"
44311,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.094594595,"origin, which, a, that, in, and, the"
44312,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.094594595,"to, sars-cov-2, and, has, been, that, with"
44313,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.094594595,"that, are, the, sars-cov-2, to, this, of"
44314,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.094594595,"the, of, a, and, which, genomic, viruses"
44315,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.094594595,"origin, the, that, by, from, and, this"
44316,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.094594595,"in, into, and, sars-cov-2, with, that, the"
44317,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.094594595,"that, more, than, the, to, of, and"
44318,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.094594595,"sars-cov-2, from, a, of, in, the, and"
44319,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.094594595,"to, sars-cov-2, from, in, and, it, that"
44320,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.094594595,"the, were, that, collected, earliest, with, as"
44321,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.094594595,"virus, the, covid-19, was, to, that, same"
44322,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.094594595,"to, this, that, the, virus, of, we"
44323,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.094594595,"covid-19, a, in, the, that, from, for"
44324,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.094594595,"the, in, of, to, that, we, was"
44325,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.094594595,"a, of, the, that, covid-19, and, with"
44326,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.094594595,"a, as, the, of, in, with, that"
44327,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.094594595,"was, at, the, to, of, found, bats"
44328,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.094594595,"the, of, sars-cov, and, bat, that, sequence"
44329,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.094594595,"that, of, homology, with, sars-cov-2, analysis, the"
44330,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.094594595,"in, the, of, was, virus, human, and"
44331,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.094594595,"as, and, the, of, to, be, natural"
44332,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.094594595,"to, the, coronavirus, bats, of, and, a"
44333,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.094594595,"a, of, the, from, sars-cov-2, and, in"
44334,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.094594595,"in, with, the, and, sars-cov-2, of, bat"
44335,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.094594595,"on, in, the, of, identified, most, these"
44336,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.094594595,"from, a, of, in, the, suggested, that"
44337,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.094594595,"sequence, bat, that, the, of, and, sars-cov"
44338,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.094594595,"the, and, a, ace2, that, of, common"
44339,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.094594595,"on, identified, in, the, of, these, most"
44340,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.094594595,"reported, that, the, to, suggesting, be, of"
44341,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.094594595,"the, of, a, to, in, was, isolated"
44342,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.094594595,"a, of, the, genomic, and, which, viruses"
44343,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.094594595,"homology, with, that, the, of, sars-cov-2, analysis"
44344,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","bats are also important reservoir species for a great 

range of coronaviruses",0.094594595,"range, of, also, are, a, bats, for"
44345,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.094594595,"reported, the, sars-cov-2, to, in, of, and"
44346,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.094594595,"the, sars-cov-2, and, to, be, of, is"
44347,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.094594595,"and, to, the, be, natural, of, as"
44348,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.094594595,"the, as, of, that, to, such, and"
44349,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.094594595,"and, also, with, species, or, a, may"
44350,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.094594595,"hosts, of, and, a, that, in, as"
44351,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.094594595,"on, and, with, to, pangolins, may, be"
44352,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.094594595,"reported, that, the, sars-cov-2, to, in, and"
44353,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.094594595,"the, of, is, by, for, to, through"
44354,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.094594595,"that, it, sars-cov-2, to, from, and, in"
44355,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.094594595,"in, the, of, a, from, suggested, that"
44356,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.094594595,"a, of, the, has, been, that, to"
44357,"bats are also important reservoir species for a great 

range of coronaviruses","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.094594595,"bats, are, also, for, a, range, of"
44358,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.094594595,"are, a, the, and, in, with, to"
44359,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.094594595,"the, of, to, through, is, for, by"
44360,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.094594595,"the, covid-19, a, of, with, that, and"
44361,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.094594595,"that, by, a, of, with, and, the"
44362,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.094594595,"virus, the, to, and, sequence, that, human"
44363,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.094594595,"the, earliest, that, with, were, as, collected"
44364,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.094594595,"the, of, from, with, a, and, or"
44365,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.094594595,"the, to, this, that, in, with, of"
44366,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.094594595,"human, and, virus, the, was, in, of"
44367,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.094594595,"virus, from, in, at, the, sequence, of"
44368,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.094594595,"the, of, from, a, and, sars-cov-2, or"
44369,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.094594595,"of, the, sars-cov-2, lineage, in, from, and"
44370,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.094594595,"to, on, the, in, and, evidence, that"
44371,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.094594595,"a, that, for, with, the, to, virus"
44372,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.094594595,"that, the, near, by, of, natural, and"
44373,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.094594595,"that, the, of, in, was, to, we"
44374,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.094594595,"that, the, sars-cov-2, to, in, this, of"
44375,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.094594595,"the, of, and, from, a, or, with"
44376,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.094594595,"and, the, or, of, sars-cov-2, from, a"
44377,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.094594595,"in, the, and, that, sars-cov-2, is, of"
44378,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.094594595,"the, and, have, to, a, of, in"
44379,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.094594595,"and, a, to, the, coronavirus, bats, of"
44380,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.094594595,"the, of, that, in, this, with, to"
44381,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.094594595,"bats, the, of, can, and, in, host"
44382,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.094594595,"may, also, a, species, and, with, or"
44383,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.094594595,"and, may, be, to, pangolins, on, with"
44384,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.094594595,"the, to, was, isolated, in, of, a"
44385,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.094594595,"lineage, and, the, of, sars-cov-2, in, from"
44386,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.094594595,"in, the, of, at, virus, from, sequence"
44387,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.094594595,"to, a, of, the, has, been, that"
44388,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.094594595,"origin, the, from, this, by, that, and"
44389,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.094594595,"the, by, and, to, that, is, ratg13"
44390,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.094594595,"and, from, to, be, that, the, is"
44391,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.094594595,"are, to, that, the, of, sars-cov-2, this"
44392,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.094594595,"of, reported, be, to, the, suggesting, that"
44393,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.094594595,"in, of, reported, to, sars-cov-2, and, the"
44394,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.094594595,"reported, that, the, to, and, in, sars-cov-2"
44395,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.094594595,"and, near, the, of, that, by, natural"
44396,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.094594595,"the, in, of, to, that, sars-cov-2, this"
44397,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.094594595,"of, the, in, and, that, sars-cov-2, with"
44398,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.094594595,"bats, the, was, found, to, at, of"
44399,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.094594595,"by, a, of, the, that, and, with"
44400,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.094594595,"in, the, a, novel, coronavirus, that, and"
44401,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.094594595,"that, the, sars-cov-2, with, in, of, and"
44402,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.094594595,"on, evidence, in, the, and, that, to"
44403,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.094594595,"the, with, and, that, sars-cov-2, into, in"
44404,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.094594595,"sars-cov-2, and, with, the, of, bat, in"
44405,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.094594595,"sars-cov-2, the, and, in, that, of, is"
44406,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.094594595,"is, to, the, that, ratg13, by, and"
44407,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.094594595,"in, cluster, of, sars-cov-2, to, with, that"
44408,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.094594595,"of, to, the, we, virus, that, this"
44409,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.094594595,"in, a, the, that, covid-19, from, for"
44410,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.094594595,"in, with, to, that, sars-cov-2, of, cluster"
44411,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.094594595,"in, a, of, and, that, as, hosts"
44412,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.094594595,"from, hosts, that, natural, to, and, the"
44413,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.094594595,"that, the, of, and, ace2, a, common"
44414,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.094488189,"that, to, human, such, he, the, an, a, of, has, otherwise, for"
44415,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.094488189,"a, of, the, market, animal, and, live, officials, in, an, from, positive"
44416,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.094488189,"he, of, has, for, to, human, a, such, otherwise, that, an, the"
44417,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.094488189,"in, officials, the, market, live, positive, from, an, animal, and, a, of"
44418,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.094339623,"a, coronaviruses, n, in, bats"
44419,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.094339623,"viruses, in, bats, of, a"
44420,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.094339623,"coronaviruses, in, horseshoe, bats, of"
44421,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.094339623,"that, in, infect, and, from"
44422,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.094339623,"the, from, in, or, and"
44423,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.094339623,"bats, a, of, the, new"
44424,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.094339623,"the, that, in, and, southeast"
44425,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.094339623,"the, of, and, in, bats"
44426,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.094339623,"in, a, to, very, and"
44427,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.094339623,"sars-cov-2, and, in, related, coronaviruses"
44428,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.094339623,"viruses, of, the, from, and"
44429,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.094339623,"are, of, a, large, in"
44430,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.094339623,"of, bats,, that, bats, with, and, or, were, virus, for"
44431,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.094339623,"that, study, for, animals, with"
44432,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.094339623,"that, bats, more, for, than"
44433,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.094339623,"many, and, to, in, such"
44434,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.094339623,"and, sars-cov-2, to, than, in"
44435,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.094339623,"of, bats, and, more, than"
44436,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.094339623,"sars-, cov-2, identified, and, to"
44437,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.094339623,"a, for, coronavirus, is, and"
44438,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.094339623,"to, bat, the, of, from"
44439,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.094339623,"and, have, sars-cov, of, bat"
44440,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.094339623,"as, to, the, of, a"
44441,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.094339623,"sars-cov-2, a, to, it, in"
44442,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.094339623,"the, sars-cov-2, with, of, to"
44443,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.094339623,"that, sars-cov-2, to, viruses,, the"
44444,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.094339623,"the, of, viruses,, to, genetic"
44445,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.094339623,"of, the, have, in, which"
44446,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.094339623,"the, a, from, is, also"
44447,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.094339623,"the, that, sars-cov-2, was, from"
44448,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.094339623,"the, viral, are, of, and"
44449,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.094339623,"that, other, sars-cov-2, and, is"
44450,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.094339623,"a, is, and, shares, with"
44451,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.094339623,"that, with, genetic, sars-cov-2, is"
44452,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.094339623,"of, are, human, coronaviruses, and"
44453,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.094339623,"bat, and, the, are, all"
44454,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.094339623,"that, the, bat, as, to"
44455,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.094339623,"a, to, sars-cov-2, the, bat"
44456,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.094339623,"the, of, viruses, a, and"
44457,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.094339623,"the, and, a, are, of"
44458,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.094339623,"covid-19, the, that, sars-cov-2, human"
44459,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.094339623,"in, the, to, and, with"
44460,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.094339623,"the, have, reservoirs, of, and"
44461,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.094339623,"that, a, the, its, in"
44462,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.094339623,"a, of, in, the, human"
44463,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.094339623,"the, of, have, and, reservoirs"
44464,"Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.094339623,"is, a, for, and, coronavirus"
44465,"Bats are the second  

largest order of mammals, with over 1,230 species.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.094339623,"bats, are, the, of, with"
44466,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.094339623,"was, that, the, in, a"
44467,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.094339623,"is, that, a, the, virus"
44468,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.094339623,"of, intermediate, in, malayan, the"
44469,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.094339623,"the, in, highly, of, sars-cov-2,"
44470,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.094339623,"the, for, of, to, from"
44471,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.094339623,"the, of, is, to, animal"
44472,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.094339623,"this, the, covid-19, in, of"
44473,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.094339623,"this, of, china,, in, the"
44474,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.094339623,"in, is, the, of, on"
44475,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.094339623,"the, a, of, to, and"
44476,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.094339623,"the, that, virus, can, animals"
44477,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.094339623,"to, that, natural, the, and"
44478,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.094339623,"the, from, in, yunnan, province,"
44479,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.094339623,"the, sars-cov-2, to, a, is"
44480,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.094339623,"a, to, the, coronavirus, with"
44481,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.094339623,"the, a, from, bats,, to"
44482,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.094339623,"the, sars-cov, and, in, to"
44483,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.094339623,"from, was, in, china, the"
44484,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.094339623,"sars-cov-2, is, bat, that, in"
44485,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.094339623,"bats, are, natural, of, that"
44486,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.094339623,"with, the, and, to, in"
44487,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.094339623,"and, are, the, transmitted, respiratory"
44488,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.094339623,"to, the, for, in, and"
44489,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.094339623,"from, the, that, in, for"
44490,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.094339623,"was, to, the, in, animals"
44491,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.094339623,"the, and, to, are, of"
44492,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.094339623,"the, and, that, a, in"
44493,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.094339623,"the, that, in, a, and"
44494,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.094339623,"a, zoonotic, and, the, one"
44495,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.094339623,"a, by, in, that, the"
44496,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.094339623,"the, and, a, in, that"
44497,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.094339623,"and, identified, to, sars-, cov-2"
44498,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.094339623,"through, that, to, sars-cov-2, and"
44499,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.094339623,"to, has, that, sars-cov-2, and"
44500,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.094339623,"are, as, in, from, a"
44501,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.094339623,"the, from, a, of, sars-cov-2"
44502,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.094339623,"a, the, as, natural, of"
44503,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.094339623,"the, of, a, from, that"
44504,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.094339623,"and, are, sars-cov-2, the, genome"
44505,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.094339623,"are, genomic, sars-cov-2, the, and"
44506,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.094339623,"and, the, of, from, bat"
44507,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.094339623,"the, and, not, that, of"
44508,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.094339623,"the, that, ratg13, from, and"
44509,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.094339623,"to, the, of, from, bat"
44510,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.094339623,"the, of, huanan, market, at"
44511,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.094339623,"that, sars-cov-2, through, and, to"
44512,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.094339623,"to, sars-cov-2, the, that, of"
44513,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.094339623,"that, and, in, at, market"
44514,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.094339623,"of, cases, the, huanan, that"
44515,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.094339623,"at, the, of, with, sars-cov-2"
44516,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.094339623,"to, that, the, are, more"
44517,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.094339623,"in, lineage, the, of, a"
44518,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.094339623,"in, the, this, is, of"
44519,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.094339623,"a, of, the, at, origin"
44520,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.094339623,"the, consistent, with, of, is"
44521,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.094339623,"consistent, the, of, and, origin"
44522,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.094339623,"at, the, in, that, animal"
44523,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.094339623,"in, zoonotic, to, of, and"
44524,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.094339623,"sars-cov-2, and, of, from, in"
44525,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.094339623,"and, to, in, a, very"
44526,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.094339623,"zoonotic, of, in, and, to"
44527,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.094339623,"to, a, and, the, as"
44528,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.094339623,"from, that, a, sars-cov-2, spillover"
44529,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.094339623,"that, of, to, and, the"
44530,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.094339623,"in, from, a, an, animal"
44531,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.094339623,"of, sars-cov-2, the, in, animals"
44532,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.094339623,"the, a, of, including, and"
44533,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.094339623,"a, of, lineage, the, in"
44534,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.094339623,"a, that, sars-cov-2, from, spillover"
44535,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.094339623,"that, of, to, humans, an, is, a, coronavirus, the, 2"
44536,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.094339623,"sars-cov-2, other, and, is, that"
44537,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.094339623,"in, it, that, and, an"
44538,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.094339623,"evidence, sars-cov-2, a, in, that"
44539,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.094339623,"that, sars-cov-2, the, market,, animals"
44540,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.094339623,"the, market,, that, with, animals"
44541,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.094339623,"genome, a, the, from, in"
44542,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.094339623,"in, a, to, that, events"
44543,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.094339623,"the, is, that, in, of, were, and, a, but, not"
44544,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.094339623,"in, a, that, from, to"
44545,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.094339623,"in, from, an, animal, a"
44546,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.094339623,"scientists, that, the, was, outbreak"
44547,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.094339623,"sars-cov-2, a, and, was, an"
44548,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.094339623,"samples, that, taken, the, animals"
44549,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.094339623,"the, that, to, of, at"
44550,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.094339623,"to, have, at, the, market"
44551,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.094339623,"the, animals, samples, taken, that"
44552,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.094339623,"and, that, from, in, infect"
44553,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.094339623,"and, in, their, which, human"
44554,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.094339623,"is, and, from, to, coronavirus"
44555,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.094339623,"sequence, the, a, coronavirus, that"
44556,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.094339623,"as, the, of, to, be"
44557,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.094339623,"in, the, of, that, to"
44558,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.094339623,"the, center, and, were, in, with, of, a, to, that"
44559,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.094339623,"the, of, virus, to, that"
44560,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.094339623,"to, in, the, which, that"
44561,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.094339623,"in, other, of, such, as"
44562,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.094339623,"of, the, virus, from, and"
44563,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.094339623,"the, of, to, and, which"
44564,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.094339623,"and, to, the, sars-cov-2, is"
44565,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.094339623,"a, sars-cov-2, to, be, that"
44566,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.094339623,"to, the, of, from, for"
44567,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.094339623,"has, the, of, which, with"
44568,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.094339623,"the, of, a, horseshoe, to, that, with, and, virus, for"
44569,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.094339623,"that, the, and, bat, pangolin"
44570,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.094339623,"a, have, the, to, from"
44571,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.094339623,"the, a, that, to, and"
44572,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.094339623,"that, sars-cov-2, has, and, to"
44573,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.094339623,"the, and, a, of, sars-cov-2"
44574,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.094339623,"the, that, of, genetic, sars-cov-2"
44575,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.094339623,"hosts, of, and, to, human"
44576,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.094339623,"of, sequences, to, which, was"
44577,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.094339623,"the, from, was, to, and"
44578,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.094339623,"the, origins, in, a, to"
44579,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.094339623,"the, are, market, and, in"
44580,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.094339623,"the, bats, in, and, china"
44581,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.094339623,"to, the, bats, and, a, in, from, that, have, humans"
44582,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.094339623,"the, of, genetic, in, was"
44583,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.094339623,"evidence, that, the, of, all"
44584,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.094339623,"the, as, a, of, that"
44585,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.094339623,"the, that, to, and, more"
44586,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.094339623,"believe, that, the, in, to"
44587,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.094339623,"the, of, and, huanan, in"
44588,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.094339623,"is, to, be, the, reservoir"
44589,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.094339623,"the, to, reservoir, intermediate, and"
44590,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.094339623,"shares, with, and, is, a"
44591,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.094339623,"the, as, a, of, natural"
44592,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.094339623,"the, for, wild, and, of"
44593,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.094339623,"the, and, a, palm, civet"
44594,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.094339623,"it, the, and, of, bat"
44595,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.094339623,"sars-cov-2, the, that, to, viruses,"
44596,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.094339623,"to, the, reservoir, is, be"
44597,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.094339623,"scientists, that, was, the, outbreak"
44598,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.094339623,"however,, it, in, the, that"
44599,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.094339623,"a, the, that, in, was"
44600,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.094339623,"as, the, of, may, a"
44601,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.094339623,"that, the, wuhan, of, or"
44602,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.094339623,"the, of, it, that, as"
44603,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.094339623,"after, the, group, of, bat"
44604,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.094339623,"genomic, that, the, bats, of"
44605,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.094339623,"the, key, of, a, with"
44606,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.094339623,"to, the, coronavirus, been, of"
44607,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.094339623,"of, to, genome, previously, bat"
44608,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.094339623,"of, the, analysis, to, beta"
44609,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.094339623,"transmission, as, was, the, for"
44610,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.094339623,"to, and, have, the, is"
44611,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.094339623,"from, a, are, as, in"
44612,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.094339623,"have, of, and, sars-cov, bat"
44613,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.094339623,"of, that, is, bat, receptor"
44614,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.094339623,"coronaviruses, in, bats, to, of"
44615,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.094339623,"and, the, or, from, in"
44616,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.094339623,"the, and, in, from, to"
44617,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.094339623,"to, in, may, the, and"
44618,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.094339623,"or, and, the, in, may"
44619,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.094339623,"evidence, that, natural, all, and"
44620,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.094339623,"and, the, that, sars-cov-2, is"
44621,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.094339623,"likely, more, species, of, and"
44622,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.094339623,"of, humans, that, an, is"
44623,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.094339623,"and, to, the, coronavirus, of"
44624,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.094339623,"the, of, in, this, covid-19"
44625,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.094339623,"the, was, isolated, in, of"
44626,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.094339623,"the, between, covid-19, and, of"
44627,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.094339623,"the, virus, in, with, different"
44628,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.094339623,"and, are, of, coronaviruses, human"
44629,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.094339623,"be, the, of, and, intermediate"
44630,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.094339623,"analysis, the, to, of, beta"
44631,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.094339623,"that, the, of, genomes, sars-cov-2"
44632,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.094339623,"and, the, was, from, to"
44633,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.094339623,"the, more, to, that, and"
44634,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.094339623,"the, of, more, related, to"
44635,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.094339623,"that, the, covid-19, of, virus"
44636,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.094339623,"on, the, genome, and, that"
44637,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.094339623,"and, from, animals, to, in"
44638,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.094339623,"the, respiratory, are, transmitted, and"
44639,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.094339623,"the, of, wild, is, and"
44640,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.094339623,"the, of, and, hosts, are"
44641,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.094339623,"and, market, that, at, in"
44642,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.094339623,"the, of, to, that, within"
44643,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.094339623,"the, in, from, yunnan, province,"
44644,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.094339623,"and, from, the, bat, of"
44645,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.094339623,"of, sars-cov-2, from, in, and"
44646,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.094339623,"the, in, a, genome, from"
44647,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.094339623,"between, sars-cov-2, and, of, the, in, with, sars-cov, yunnan, bat"
44648,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.094339623,"the, between, and, of, a"
44649,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.094339623,"and, of, revealed, between, with"
44650,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.094339623,"a, analysis, of, the, that"
44651,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.094339623,"the, sequence, of, that, these"
44652,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.094339623,"the, that, with, of, sars-cov-2"
44653,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.094339623,"that, the, of, and, sars-cov-2"
44654,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.094339623,"s, sequence, sars-cov-2,, that, of"
44655,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.094339623,"bats, the, to, be, of"
44656,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.094339623,"the, animals, that, sars-cov-2, market,"
44657,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.094339623,"the, market,, that, of, animals"
44658,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.094339623,"the, that, sars-cov-2, from, for"
44659,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.094339623,"n, coronaviruses, a, in, bats"
44660,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.094339623,"species, to, sars-cov-2, and, in"
44661,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.094339623,"is, to, sars-cov-2, be, in"
44662,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.094339623,"between, and, that, in, sars-cov-2"
44663,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.094339623,"of, the, that, sars-cov-2, genomes"
44664,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.094339623,"a, the, that, of, at"
44665,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.094339623,"the, of, and, acid, sars-cov-2"
44666,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.094339623,"that, as, may, to, no"
44667,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.094339623,"the, coronavirus, has, a, sequence"
44668,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.094339623,"to, the, of, at, that"
44669,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.094339623,"that, the, of, at, a"
44670,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.094339623,"sars-cov-2, of, the, with, infection"
44671,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.094339623,"the, of, cases, huanan, that"
44672,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.094339623,"have, to, the, at, market"
44673,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.094339623,"the, in, to, from, a"
44674,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.094339623,"of, bat, a, in, the"
44675,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.094339623,"a, pangolin, and, sars-cov-2, spike"
44676,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.094339623,"a, on, the, in, pangolin"
44677,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.094339623,"other, such, as, of, in"
44678,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.094339623,"of, been, or, other, have"
44679,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.094339623,"of, in, the, has, been"
44680,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.094339623,"closely, related, to, the, which"
44681,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.094339623,"in, the, of, virus, similarities"
44682,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.094339623,"a, by, was, the, to"
44683,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.094339623,"a, of, the, new, bats"
44684,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.094339623,"sars-cov-2, to, and, viruses, in"
44685,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.094339623,"for, the, of, wild, and"
44686,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.094339623,"the, bats, were, as, for, and, a, of, from, genome"
44687,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.094339623,"between, sars-cov-2, and, sars-cov, with, the, of, bat, in, yunnan"
44688,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.094339623,"as, a, of, the, to"
44689,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.094339623,"the, may, as, a, of"
44690,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.094339623,"the, of, to, human, a"
44691,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.094339623,"a, of, the, to, human"
44692,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.094339623,"that, the, wuhan, or, of"
44693,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.094339623,"there, coronaviruses, to, sars-cov-2, the"
44694,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.094339623,"highly, sars-cov-2, the, virus, genome"
44695,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.094339623,"and, sars-cov-2, the, to, 2"
44696,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.094339623,"the, within, to, that, of"
44697,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.094339623,"to, the, of, a, human"
44698,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.094339623,"the, to, for, a, is"
44699,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.094339623,"in, the, of, malayan, intermediate"
44700,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.094339623,"2, that, to, the, an, coronavirus, humans, a, of, is"
44701,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.094339623,"shares, homology, with, that, of"
44702,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.094339623,"is, that, species, of, the"
44703,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.094339623,"study, sars-cov-2, a, the, an"
44704,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.094339623,"in, of, sars-cov-2, were, with"
44705,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.094339623,"of, the, a, that, animal"
44706,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.094339623,"sars-cov-2, of, and, that, the"
44707,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.094339623,"an, and, the, from, in"
44708,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.094339623,"the, of, to, from, and"
44709,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.094339623,"of, the, ace2, from, species"
44710,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.094339623,"of, to, and, the, sars-cov-2"
44711,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.094339623,"the, of, with, sars-cov-2, at"
44712,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.094339623,"the, has, of, which, with"
44713,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.094339623,"et, of, with, the, sars-cov-2"
44714,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.094339623,"of, that, s, sequence, sars-cov-2,"
44715,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.094339623,"that, of, shares, homology, with"
44716,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.094339623,"furin, cleavage, at, the, s1/s2"
44717,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.094339623,"the, to, most, in, and"
44718,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.094339623,"the, to, from, is, most"
44719,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.094339623,"a, due, to, in, the"
44720,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.094339623,"the, to, be, of, as"
44721,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.094339623,"and, sars-cov-2, in, to, than"
44722,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.094339623,"the, and, to, rbd, that"
44723,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.094339623,"that, in, the, however,, it"
44724,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.094339623,"it, that, are, the, to"
44725,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.094339623,"the, a, to, that, and"
44726,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.094339623,"in, to, the, and, was"
44727,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.094339623,"the, sars-cov-2, to, a, that"
44728,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.094339623,"also, the, of, may, to"
44729,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.094339623,"sars-cov-2, and, species, to, in"
44730,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.094339623,"several, in, to, sars-cov-2, and"
44731,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.094339623,"in, of, the, genetic, was"
44732,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.094339623,"of, that, the, from, intermediate"
44733,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.094339623,"in, the, that, from, for"
44734,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.094339623,"that, the, of, for, sars-cov-2"
44735,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.094339623,"evidence, that, sars-cov-2, a, in"
44736,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.094339623,"evidence, that, from, bats, in, the, south, a, and, of"
44737,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.094339623,"it, that, sars-cov-2, of, a"
44738,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.094339623,"that, the, covid-19, virus, of"
44739,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.094339623,"virus, highly, genome, the, sars-cov-2"
44740,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.094339623,"the, covid-19, a, from, is"
44741,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.094339623,"that, sars-cov-2, from, a, it"
44742,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.094339623,"of, the, covid-19, virus, in"
44743,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.094339623,"and, are, of, the, viral"
44744,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.094339623,"the, in, bats, and, china"
44745,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.094339623,"and, more, likely, of, species"
44746,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.094339623,"to, the, and, reservoir, intermediate"
44747,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.094339623,"and, that, the, in, southeast"
44748,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.094339623,"the, and, in, most, to"
44749,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.094339623,"the, and, in, viruses, to"
44750,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.094339623,"the, of, in, china,, this"
44751,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.094339623,"viruses, in, closely, to, the"
44752,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.094339623,"origins, the, to, a, in"
44753,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.094339623,"the, to, believe, that, in"
44754,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.094339623,"a, of, to, with, sars-cov-2"
44755,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.094339623,"of, to, sars-cov-2, with, a"
44756,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.094339623,"a, with, which, to, sars-cov-2"
44757,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.094339623,"a, of, sars-cov-2, which, to"
44758,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.094339623,"to, is, similar, related, bat"
44759,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.094339623,"sars-cov-2, and, are, the, genome"
44760,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.094339623,"to, which, a, with, sars-cov-2"
44761,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.094339623,"the, to, and, both, in"
44762,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.094339623,"the, related, to, which, a"
44763,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.094339623,"that, and, to, the, rbd"
44764,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.094339623,"the, is, that, in, for, researchers, of, to, by, a"
44765,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.094339623,"have, to, the, of, that"
44766,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.094339623,"the, to, with, rbd, of"
44767,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.094339623,"have, the, and, is, to"
44768,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.094339623,"the, which, closely, related, to"
44769,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.094339623,"the, acid, of, sars-cov-2, and"
44770,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.094339623,"the, genetic, of, to, viruses,"
44771,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.094339623,"group, of, the, after, bat"
44772,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.094339623,"is, the, bat, strain, by"
44773,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.094339623,"sars-cov-2, is, be, to, in"
44774,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.094339623,"the, to, be, sars-cov-2, is"
44775,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.094339623,"genomic, sars-cov-2, and, are, the"
44776,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.094339623,"the, in, to, and, may"
44777,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.094339623,"there, the, to, sars-cov-2, coronaviruses"
44778,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.094339623,"is, in, the, that, it"
44779,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.094339623,"of, to, a, was, from"
44780,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.094339623,"a, positive, collected, and, were, to, of, located, in, the"
44781,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.094339623,"for, and, with, from, to, the, in, of, collected, a"
44782,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.094339623,"have, that, the, in, bats, and, to, humans, from, a"
44783,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.094339623,"the, of, bats, were, as, a, for, genome, from, and"
44784,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.094339623,"of, bats,, and, that, bats, for, virus, were, with, or"
44785,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.094339623,"of, that, the, a, ace2, species, as, intermediate, or, for"
44786,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.094339623,"and, a, similarity, of, in, which, the, for, viruses, to"
44787,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.094339623,"of, that, the, bat, a, ace2, receptor, from, as, for"
44788,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.094339623,"evidence, from, a, of, in, bats, the, and, south, that"
44789,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.094339623,"in, horseshoe, bats, are, to, that, of, based, on, and"
44790,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.094339623,"for, the, of, and, collected, from, a, in, with, to"
44791,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.094339623,"from, its, and, to, was, for, the, of, in, a"
44792,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.094339623,"a, the, of, and, in, that, not, were, but, is"
44793,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.094339623,"the, of, is, by, for, in, researchers, a, to, that"
44794,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.094339623,"cases, and, the, huanan, that, for, of, in, a, by"
44795,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.094339623,"in, the, of, located, positive, collected, to, were, a, and"
44796,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.094339623,"shows, the, of, and, to"
44797,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.094339623,"of, the, covid-19, between, and"
44798,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.094339623,"a, between, and, the, of"
44799,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.094339623,"to, the, that, and, this"
44800,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.094339623,"are, and, the, market, in"
44801,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.094339623,"the, huanan, that, in, for, of, cases, by, and, a"
44802,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.094339623,"the, that, a, virus, found"
44803,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.094339623,"the, wildlife, on, most, with, a, to, that, infected, virus"
44804,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.094339623,"in, the, a, to, and"
44805,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.094339623,"in, the, and, a, of"
44806,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.094339623,"in, the, of, a, to"
44807,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.094339623,"a, the, natural, of, and"
44808,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.094339623,"to, in, the, of, natural"
44809,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.094339623,"a, was, sars-cov-2, and, an"
44810,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.094339623,"a, the, in, with, sars-cov-2"
44811,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.094339623,"that, the, with, in, a"
44812,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.094339623,"that, sars-cov-2, a, the, virus"
44813,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.094339623,"ace2, of, to, sars-cov-2, the"
44814,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.094339623,"this, the, that, likely, sars-cov-2"
44815,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.094339623,"sars-cov-2, a, of, it, that"
44816,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.094339623,"it, that, the, as, of"
44817,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.094339623,"it, is, that, the, of"
44818,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.094339623,"that, the, in, to, a"
44819,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.094339623,"to, the, in, which, that"
44820,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.094339623,"in, it, is, that, the"
44821,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.094339623,"is, to, the, that, in"
44822,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.094339623,"of, in, natural, to, the"
44823,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.094339623,"that, the, for, of, including"
44824,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.094339623,"the, of, natural, a, that"
44825,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.094339623,"the, virus, of, to, that"
44826,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.094339623,"a, the, sars-cov-2, from, or"
44827,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.094339623,"and, sars-cov-2, related, coronaviruses, in"
44828,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.094339623,"and, that, not, the, of"
44829,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.094339623,"the, is, and, not, of"
44830,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.094339623,"from, animals, in, to, and"
44831,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.094339623,"this, the, in, that, virus"
44832,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.094339623,"a, virus, that, found, the"
44833,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.094339623,"this, the, that, originated, in"
44834,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.094339623,"in, the, almost, that, virus"
44835,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.094339623,"in, a, study, the, of"
44836,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.094339623,"of, and, the, in, bats"
44837,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.094339623,"the, and, in, bats, to"
44838,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.094339623,"in, and, both, to, the"
44839,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.094339623,"and, of, in, the, to"
44840,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.094339623,"the, that, from, to, and"
44841,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.094339623,"receptor, that, is, of, bat"
44842,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.094339623,"ace2, from, species, of, the"
44843,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.094339623,"the, of, from, that, intermediate"
44844,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.094339623,"the, of, a, species, that, as, intermediate, or, ace2, for"
44845,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.094339623,"from, the, for, a, that, bat, ace2, as, receptor, of"
44846,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.094339623,"of, a, that, the, bat"
44847,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.094339623,"sequence, the, of, that, these"
44848,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.094339623,"the, that, these, of, use"
44849,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.094339623,"of, the, genomic, that, bats"
44850,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.094339623,"the, of, that, intermediate, to"
44851,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.094339623,"can, be, to, and, are"
44852,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.094339623,"and, in, to, are, direct"
44853,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.094339623,"the, is, be, in, to"
44854,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.094339623,"the, which, have, of, in"
44855,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.094339623,"that, the, of, have, in"
44856,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.094339623,"of, a, viruses, in, bats"
44857,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.094339623,"the, of, been, to, coronavirus"
44858,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.094339623,"evidence, all, that, the, of"
44859,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.094339623,"all, evidence, that, natural, and"
44860,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.094339623,"of, the, have, in, that"
44861,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.094339623,"indicates, that, the, of, and"
44862,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.094339623,"animals, can, that, virus, the"
44863,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.094339623,"the, virus, in, different, with"
44864,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.094339623,"the, animals, that, with, market,"
44865,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.094339623,"that, of, the, market,, animals"
44866,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.094339623,"that, of, is, species, the"
44867,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.094339623,"the, in, or, and, may"
44868,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.094339623,"from, the, is, to, bats"
44869,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.094339623,"are, and, can, be, to"
44870,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.094339623,"another, be, a, virus, and"
44871,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.094339623,"the, of, and, a, in"
44872,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.094339623,"the, and, a, in, of"
44873,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.094339623,"and, viruses, from, of, the"
44874,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.094339623,"the, have, been, in, of"
44875,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.094339623,"on, the, of, in, is"
44876,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.094339623,"of, sequence, from, in, province"
44877,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.094339623,"that, the, of, were, in, center, to, with, a, and"
44878,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.094339623,"a, virus, that, with, infected, wildlife, on, to, the, most"
44879,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.094339623,"in, the, from, and, an"
44880,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.094339623,"the, and, a, of, is"
44881,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.094339623,"the, a, of, that, and"
44882,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.094339623,"is, also, from, a, the"
44883,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.094339623,"the, for, is, to, a"
44884,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.094339623,"the, from, is, most, to"
44885,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.094339623,"is, a, the, covid-19, from"
44886,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.094339623,"a, related, which, to, the"
44887,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.094339623,"the, and, a, zoonotic, one"
44888,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.094339623,"to, the, a, from, bats,"
44889,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.094339623,"bat, cov, and, sars-cov-2, with"
44890,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.094339623,"a, sars-cov-2, spike, and, pangolin"
44891,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.094339623,"a, origin, of, at, the"
44892,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.094339623,"have, been, other, of, or"
44893,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.094339623,"the, also, that, are, virus"
44894,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.094339623,"a, in, it, to, sars-cov-2"
44895,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.094339623,"it, that, sars-cov-2, a, from"
44896,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.094339623,"it, in, a, to, sars-cov-2"
44897,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.094339623,"a, sars-cov-2, in, an, to"
44898,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.094339623,"that, a, sars-cov-2, is, to"
44899,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.094339623,"is, humans, that, of, an"
44900,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.094339623,"that, may, as, no, to"
44901,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.094339623,"for, and, from, to, the, in, of, its, a, was"
44902,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.094339623,"as, the, was, for, transmission"
44903,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.094339623,"the, of, and, virus, human"
44904,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.094339623,"sars-cov-2, genetic, with, is, that"
44905,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.094339623,"with, the, sars-cov-2, is, of"
44906,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.094339623,"is, consistent, with, of, the"
44907,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.094339623,"of, genetic, that, sars-cov-2, the"
44908,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.094339623,"of, the, sars-cov-2, with, that"
44909,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.094339623,"the, of, that, these, use"
44910,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.094339623,"the, also, that, are, for"
44911,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.094339623,"that, are, the, for, of"
44912,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.094339623,"it, that, the, an, of"
44913,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.094339623,"the, pangolin, in, on, a"
44914,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.094339623,"the, by, is, bat, strain"
44915,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.094339623,"a, bat, by, the, in"
44916,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.094339623,"coronaviruses, of, in, horseshoe, bats"
44917,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.094339623,"of, in, to, coronaviruses, bats"
44918,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.094339623,"several, to, sars-cov-2, and, in"
44919,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.094339623,"are, to, in, of, based, horseshoe, on, that, bats, and"
44920,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.094339623,"and, that, in, of, sars-cov-2"
44921,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.094339623,"and, that, from, the, ratg13"
44922,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.094339623,"the, is, and, an, to"
44923,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.094339623,"in, the, was, animals, to"
44924,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.094339623,"in, the, of, sars-cov-2, animals"
44925,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.094339623,"a, the, has, coronavirus, sequence"
44926,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.094339623,"that, natural, to, and, the"
44927,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.094339623,"of, to, be, origin, that"
44928,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.094339623,"the, from, a, and, to"
44929,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.094339623,"bats, are, hosts, and, that"
44930,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.094339623,"the, also, are, that, virus"
44931,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.094339623,"the, that, are, also, for"
44932,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.094339623,"it, the, are, to, that"
44933,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.094339623,"of, that, the, bat, a"
44934,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.094339623,"a, the, bat, in, by"
44935,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.094339623,"of, sequences, which, was, to"
44936,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.094339623,"genome, of, to, bat, previously"
44937,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.094339623,"was, from, a, to, of"
44938,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.094339623,"from, in, province, sequence, of"
44939,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.094339623,"in, the, of, a, human"
44940,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.094339623,"human, their, in, which, and"
44941,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.094339623,"to, 2, and, the, sars-cov-2"
44942,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.094339623,"to, of, which, a, sars-cov-2"
44943,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.094339623,"in, a, of, to, the, which, for, and, similarity, viruses"
44944,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.094339623,"sars-cov-2, a, to, in, an"
44945,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.094339623,"sars-cov-2., and, pangolin, to, in"
44946,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.094339623,"in, of, to, pangolin, which"
44947,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.094339623,"study, animals, that, for, with"
44948,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.094339623,"the, et, of, with, sars-cov-2"
44949,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.094339623,"that, the, sars-cov-2, and, pangolin"
44950,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.094339623,"on, the, genome, that, and"
44951,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.094339623,"that, the, and, viruses, bats"
44952,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.094339623,"that, the, closest, and, to"
44953,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.094339623,"viruses, the, and, that, bats"
44954,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.094339623,"is, to, in, the, that"
44955,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.094339623,"the, that, in, this, originated"
44956,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.094339623,"in, pangolin, and, to, sars-cov-2."
44957,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.094339623,"sars-cov-2, with, the, bat, in"
44958,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.094339623,"more, than, that, bats, for"
44959,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.094339623,"the, clustering, that, sars-cov-2, in"
44960,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.094339623,"the, sars-cov-2, likely, that, this"
44961,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.094339623,"that, pangolin, and, the, sars-cov-2"
44962,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.094339623,"sars-cov-2, of, and, the, or"
44963,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.094339623,"the, that, pangolin, and, bat"
44964,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.094339623,"the, and, are, all, bat"
44965,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.094339623,"with, bat, cov, and, sars-cov-2"
44966,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.094339623,"that, the, are, more, to"
44967,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.094339623,"consistent, and, origin, of, the"
44968,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.094339623,"in, the, of, similarities, virus"
44969,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.094339623,"are, to, of, the, and"
44970,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.094339623,"of, that, the, origin, a"
44971,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.094339623,"of, is, with, sars-cov-2, the"
44972,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.094339623,"with, the, of, sars-cov-2, sars-cov"
44973,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.094339623,"sars-cov-2, between, and, that, in"
44974,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.094339623,"in, that, of, sars-cov-2, and"
44975,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.094339623,"in, the, a, from, and"
44976,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.094339623,"a, the, palm, civet, and"
44977,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.094339623,"the, of, that, a, have"
44978,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.094339623,"the, including, that, for, of"
44979,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.094339623,"the, that, are, of, for"
44980,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.094339623,"that, and, for, the, in"
44981,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.094339623,"that, it, an, and, in"
44982,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.094339623,"the, of, bat, and, it"
44983,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.094339623,"in, the, this, that, of"
44984,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.094339623,"the, that, of, it, an"
44985,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.094339623,"that, sars-cov-2, was, from, the"
44986,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.094339623,"the, that, virus, in, almost"
44987,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.094339623,"in, of, pangolin, which, to"
44988,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.094339623,"be, the, that, sars-cov-2, but"
44989,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.094339623,"revealed, between, and, with, of"
44990,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.094339623,"a, of, the, with, key"
44991,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.094339623,"and, the, be, of, intermediate"
44992,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.094339623,"study, an, a, sars-cov-2, the"
44993,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.094339623,"be, a, virus, another, and"
44994,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.094339623,"the, covid-19, that, human, sars-cov-2"
44995,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.094339623,"that, sars-cov-2, from, the, for"
44996,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.094339623,"the, from, a, sars-cov-2, or"
44997,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.094339623,"that, sars-cov-2, the, but, be"
44998,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.094339623,"the, and, not, of, is"
44999,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.094339623,"is, to, the, an, and"
45000,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.094339623,"also, a, and, the, for"
45001,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.094339623,"that, in, a, to, events"
45002,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.094339623,"to, sars-cov-2, be, a, that"
45003,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.094339623,"of, were, in, with, sars-cov-2"
45004,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.094339623,"to, that, of, origin, be"
45005,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.094339623,"are, in, a, large, of"
45006,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.094339623,"in, many, such, to, and"
45007,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.094339623,"of, that, bats, are, natural"
45008,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.094339623,"to, of, hosts, and, human"
45009,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.094339623,"that, bats, and, are, hosts"
45010,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.094339623,"the, animal, at, that, in"
45011,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.094339623,"the, that, animal, of, a"
45012,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.094339623,"of, that, similar, to, the"
45013,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.094339623,"the, protein,, amino, of, to"
45014,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.094339623,"in, to, is, of, the"
45015,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.094339623,"in, the, of, sars-cov-2,, highly"
45016,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.094339623,"are, in, and, to, direct"
45017,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.094339623,"related, bat, to, is, similar"
45018,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.094339623,"the, of, to, may, also"
45019,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.094339623,"the, of, to, more, related"
45020,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.094339623,"of, amino, the, protein,, to"
45021,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.094339623,"with, sars-cov-2, the, of, infection"
45022,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.094117647,"of, to, the, in, which, that, virus, or"
45023,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.094117647,"coronavirus, a, and, with, to, be, in, the"
45024,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.094117647,"in, are, into, and, with, that, the, is"
45025,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.094117647,"sars-cov-2, from, a, of, in, the, and, that"
45026,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.094117647,"that, the, market, animals, and, of, transmission, are"
45027,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.094117647,"this, in, the, market, a, at, and, of"
45028,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.094117647,"the, sars, and, viruses, closely, related, to, in"
45029,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.094117647,"most, by, coronavirus, in, the, are, bats,, not"
45030,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.094117647,"to, the, have, in, of, that, a, covid-19"
45031,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.094117647,"of, which, to, virus, or, that, in, the"
45032,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.094117647,"the, a, of, as, is, was, that, virus"
45033,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.094117647,"the, to, of, is, that, bats, virus, and"
45034,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.094117647,"the, of, which, to, and, at, sars-cov, was"
45035,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.094117647,"the, to, of, reservoir, with, available, bats, virus"
45036,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.094117647,"of, the, 2, sequences, sars-, cov-2, with, pangolin"
45037,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.094117647,"a, of, the, from, that, sars-cov-2, and, in"
45038,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.094117647,"in, with, the, and, to, that, sars-cov-2, of"
45039,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.094117647,"the, viruses, to, closely, related, sars, in, and"
45040,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.094117647,"is, the, bat, to, its, in, of, less"
45041,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.094117647,"the, market, animals, that, are, and, of, transmission"
45042,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.094117647,"this, a, and, of, at, the, market, in"
45043,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.094117647,"with, available, bats, to, the, reservoir, of, virus"
45044,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.094117647,"the, not, to, have, that, in, with, of"
45045,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.094117647,"in, a, of, to, have, the, that, covid-19"
45046,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.094117647,"the, that, have, in, of, to, with, not"
45047,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.094117647,"the, was, to, at, which, sars-cov, of, and"
45048,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.094117647,"a, coronavirus, the, and, be, in, with, to"
45049,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.094117647,"the, are, most, coronavirus, in, by, bats,, not"
45050,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.094117647,"and, in, sars-cov-2,, that, the, of, coronavirus, natural"
45051,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.094117647,"of, sars-, cov-2, pangolin, with, sequences, the, 2"
45052,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.094117647,"are, the, is, and, in, with, that, into"
45053,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.094117647,"to, sars-cov-2, of, in, the, and, that, with"
45054,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.094117647,"the, of, sars-cov-2,, in, and, that, coronavirus, natural"
45055,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.094117647,"the, of, bat, to, in, is, less, its"
45056,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.094017094,"to, sars-cov-2, of, in, living, the, and, been, that, events, with"
45057,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.094017094,"sars-cov-2, and, of, the, been, to, in, with, that, living, events"
45058,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.094017094,"live, animal, at, markets, a, and, in, the, that, to, sars"
45059,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.094017094,"bats, of, many, and, a, several, to, zoonotic, that, in, as"
45060,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.094017094,"and, at, the, or, for, zoonotic, of, in, from, a, by"
45061,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.094017094,"a, the, at, animal, and, live, markets, in, to, sars, that"
45062,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.094017094,"at, a, from, in, for, the, or, by, zoonotic, of, and"
45063,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.094017094,"the, as, a, of, that, most, from, to, infected, by, and"
45064,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.094017094,"the, from, most, and, by, of, a, as, to, that, infected"
45065,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.094017094,"to, bats, as, several, zoonotic, and, many, a, in, of, that"
45066,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.093959732,"on, the, cave, could, be, by, these, bats., species, of, to, as, and, in"
45067,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.093959732,"in, the, of, to, on, cave, as, by, these, could, be, and, species, bats."
45068,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.09375,"that, the, in, or, a, of"
45069,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.09375,"in, the, of, that, and, a"
45070,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.09375,"the, and, in, bats, from, sars-cov-2,"
45071,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.09375,"that, a, the, of, or, from"
45072,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.09375,"to, sars-cov-2, a, in, and, coronaviruses"
45073,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.09375,"are, viruses, in"
45074,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.09375,"of, but, a"
45075,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.09375,"an, species, of"
45076,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.09375,"an, of, coronaviruses"
45077,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.09375,"the, animal, reservoir, to, species, and"
45078,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.09375,"the, known, be"
45079,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.09375,"similar, to, bat"
45080,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.09375,"sequences, and, bat"
45081,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.09375,"in, of, bats"
45082,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.09375,"to, of, and"
45083,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.09375,"in, of, to, and, more, than"
45084,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.09375,"sars-like, and, the"
45085,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.09375,"and, to, the, sars-, are, very"
45086,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.09375,"in, more, to"
45087,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.09375,"is, in, to"
45088,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.09375,"to, sars-cov-2, virus"
45089,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.09375,"sars-cov-2, 96%, to"
45090,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.09375,"a, coronavirus, and"
45091,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.09375,"for, a, is"
45092,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.09375,"of, in, china"
45093,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.09375,"the, of, from, to, bat, and"
45094,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.09375,"is, sars-cov-2, was, a, the, in"
45095,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.09375,"it, is, sars-cov-2, a, the, of"
45096,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.09375,"a, to, in, with, sars-cov-2, the"
45097,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.09375,"coronavirus, about, sars-cov-2"
45098,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.09375,"sars-cov-2, made, that"
45099,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.09375,"that, sars-cov-2, have"
45100,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.09375,"the, that, coronaviruses, from, to, any"
45101,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.09375,"of, the, been, that, have, to"
45102,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.09375,"the, that, of, genetic, sars-cov-2, it"
45103,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.09375,"to, that, the, of, have, sars-cov-2"
45104,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.09375,"a, the, in, was, is, sars-cov-2"
45105,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.09375,"was, in, by, a, sars-cov-2, the"
45106,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.09375,"also, a, sars-cov-2, in, is, the"
45107,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.09375,"to, of, the, and, that, coronaviruses"
45108,"Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.09375,"pointing, to, sars-cov-2"
45109,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.09375,"sars-cov-2, bat, cov, that, the, is"
45110,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.09375,"bat, as, origin"
45111,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.09375,"to, the, and, suggesting, that, covid-19"
45112,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.09375,"share, to, that, sars-cov-2, and, ratg13"
45113,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.09375,"covs, to, in"
45114,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.09375,"genomic, sars-cov-2, to"
45115,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.09375,"of, most, to"
45116,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.09375,"genomic, to, of"
45117,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.09375,"and, to, the, be, reservoirs, of"
45118,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.09375,"that, the, of, and, have, between"
45119,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.09375,"the, of, that, to, humans, and"
45120,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.09375,"the, of, a, in, that, bats, as, used, scale"
45121,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.09375,"the, a, that, used, as, human, in, of, its"
45122,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.09375,"a, are, to, that, the, of"
45123,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.09375,"and, can, the, of, that, a"
45124,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.09375,"is, that, a, of, into, the"
45125,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.09375,"human, virus, in"
45126,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.09375,"the, as, in"
45127,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.09375,"of, the, highly"
45128,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.09375,"as, the, case"
45129,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.09375,"bats, for, as, the, of, to"
45130,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.09375,"of, large, to, zoonotic, that, in"
45131,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.09375,"animal, and, to"
45132,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.09375,"to, and, spillover"
45133,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.09375,"the, of, and, a, adapted, to"
45134,"Coronaviruses are naturally hosted and developmentally 

formed by bats.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.09375,"are, and, by"
45135,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.09375,"and, the, bats"
45136,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.09375,"may, the, of"
45137,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.09375,"the, may, be, of, natural, and"
45138,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.09375,"of, the, outbreak"
45139,"The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.09375,"the, early, with"
45140,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.09375,"the, from, a, sequence, with, to"
45141,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.09375,"coronaviruses, of, species"
45142,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.09375,"into, the, to"
45143,"Malayan pangolins (Manis javanica)  

illegally imported into Guangdong province  

contain coronaviruses similar to SARS- 

CoV-22","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.09375,"into, coronaviruses, to"
45144,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.09375,"from, the, animals"
45145,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.09375,"from, was, the"
45146,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.09375,"in, was, the"
45147,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.09375,"of, bat, sars-cov-2"
45148,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.09375,"the, of, that, identical, to, and"
45149,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.09375,"the, of, outbreak"
45150,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.09375,"that, the, outbreak"
45151,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.09375,"of, the, viral"
45152,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.09375,"of, that, the"
45153,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.09375,"are, for, the"
45154,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.09375,"the, any, that, to, coronaviruses, from"
45155,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.09375,"a, the, novel, coronavirus, with, that"
45156,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.09375,"coronavirus, and, from, animals, to, in"
45157,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.09375,"to, and, animal"
45158,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.09375,"the, pangolins,, and"
45159,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","with the first case being linked to  

a seafood market",0.09375,"the, to, seafood"
45160,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.09375,"a, the, in"
45161,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.09375,"in, that, the"
45162,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.09375,"a, virus, that"
45163,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.09375,"are, in, to, genetic, and, transmitted"
45164,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.09375,"that, sars-cov-2, humans"
45165,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.09375,"the, to, that, sars-cov-2, of, as"
45166,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.09375,"the, hypothesis, of"
45167,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.09375,"are, a, the, of, that, to"
45168,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.09375,"the, that, are, sars-cov-2, and, of"
45169,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.09375,"we, of, sars-cov-2, and, from, their"
45170,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.09375,"the, most, intermediate"
45171,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.09375,"of, the, that, sars-cov-2, and, are"
45172,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.09375,"of, at, the, in, that, animal"
45173,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.09375,"more, to, in"
45174,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.09375,"that, a, related"
45175,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.09375,"is, a, in"
45176,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.09375,"in, with, the, and, is, of"
45177,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.09375,"virus, from, a"
45178,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.09375,"from, a, virus"
45179,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.09375,"the, of, from, at, market, virus, was, by, a"
45180,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.09375,"the, of, huanan, taken, from, market"
45181,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.09375,"animal, to, human"
45182,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.09375,"the, animal, other"
45183,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.09375,"in, than, the, animal, sampled, to, were, closely, related"
45184,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.09375,"in, were, because"
45185,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.09375,"the, reservoir, in"
45186,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.09375,"in, than, the, animal, that, at, market, was, and"
45187,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.09375,"in, the, and, that, huanan, market"
45188,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.09375,"animal, and, in"
45189,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.09375,"to, sars-cov-2, from, of, in, and"
45190,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.09375,"in, a, of, and, the, as"
45191,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.09375,"evidence, natural, or"
45192,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.09375,"most, of, the"
45193,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.09375,"con-, the, of"
45194,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.09375,"a, positive, and, of, in, the"
45195,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor",0.09375,"sars-cov-2, to, pointing"
45196,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.09375,"a, samples, to, of, in, the"
45197,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.09375,"the, of, that, is, an, animal, to, humans, by"
45198,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.09375,"is, humans, it, that, of, to, an, animal, by"
45199,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.09375,"are, viruses, to, in, and, that"
45200,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.09375,"the, and, for, of, to, there, no, in, more, be, other, at"
45201,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.09375,"a, that, sars-cov-2"
45202,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.09375,"a, in, their"
45203,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.09375,"viruses, closely, related, to, and, have, at, the, is"
45204,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.09375,"sars-cov-2, is, that, its, into, to, cause, the, most"
45205,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.09375,"in, the, of, is, to, sars-cov-2, at, that, mutations"
45206,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.09375,"at, infected, as, the, by, collected, wet, earliest, were"
45207,Genetic evidence suggesting otherwise is yet to be presented.,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.09375,"genetic, evidence, to"
45208,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.09375,"from, to, the, of, covid-19, virus"
45209,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.09375,"we, a, of, was, likely, analysis"
45210,"Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.09375,"animal, in, wuhan"
45211,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.09375,"the, of, a, or, to, that, were, in, live, other, by, market"
45212,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.09375,"the, of, have, that, an, to"
45213,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.09375,"the, taken, at, market, to, of"
45214,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.09375,"was, and, as"
45215,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.09375,"the, from, animals"
45216,"This suggests that the BANAL series may be able to directly infect  

humans.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.09375,"that, to, infect"
45217,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.09375,"natural, of, was"
45218,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.09375,"coronavirus, and, to"
45219,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.09375,"is, and, animals"
45220,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.09375,"studies, that, to"
45221,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.09375,"that, a, coronavirus"
45222,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.09375,"and, to, that, the, coronavirus, very"
45223,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.09375,"the, in, with"
45224,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.09375,"bats, the, a"
45225,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.09375,"the, of, indicate, that, in, to"
45226,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.09375,"the, that, of, covid-19, with, and"
45227,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Bats have been reported as being the rich source of 

coronaviruses",0.09375,"the, reported, of"
45228,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Bats have been reported as being the rich source of 

coronaviruses",0.09375,"have, bats, of"
45229,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Bats have been reported as being the rich source of 

coronaviruses",0.09375,"of, reported, the"
45230,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","Bats have been reported as being the rich source of 

coronaviruses",0.09375,"of, coronaviruses, as"
45231,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.09375,"from, the, with"
45232,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.09375,"about, sars-cov-2, coronavirus"
45233,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.09375,"bat, from, sars-cov-2"
45234,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.09375,"virus, to, sars-cov-2"
45235,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.09375,"that, to, originated"
45236,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.09375,"and, to, that, the, of, sars-cov-2"
45237,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.09375,"and, to, of"
45238,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.09375,"that, to, the, an, animal, humans, by, of, is"
45239,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.09375,"have, to, an, the, of, that"
45240,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.09375,"that, the, of, sars-cov-2, and, analysis"
45241,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.09375,"in, the, from, market, virus, was, to, a, and"
45242,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.09375,"in, the, and, to, from, market"
45243,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.09375,"the, to, most"
45244,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.09375,"transmitted, to, are, genetic, and, in"
45245,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.09375,"been, in, to"
45246,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.09375,"that, to, covid-19"
45247,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.09375,"at, the, that, was, of, a"
45248,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.09375,"as, was, the, of, that, a"
45249,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.09375,"the, to, likely"
45250,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.09375,"in, the, and, that, were, to"
45251,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.09375,"that, virus, in"
45252,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.09375,"is, that, to"
45253,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.09375,"origin, the, and"
45254,"Bats have been reported as being the rich source of 

coronaviruses","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.09375,"reported, the, of"
45255,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.09375,"the, and, sars-like"
45256,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.09375,"the, cov, and"
45257,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.09375,"and, bat, the"
45258,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.09375,"of, to, the, virus, that, is"
45259,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.09375,"the, of, and, virus, that, is"
45260,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.09375,"the, of, is, virus, to, that"
45261,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.09375,"and, the, be, that, zoonotic, of"
45262,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.09375,"and, to, the, of, that, may"
45263,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.09375,"to, sars-, the, and, may, for"
45264,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.09375,"a, positive, on, and, of, the"
45265,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.09375,"of, the, con-"
45266,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.09375,"the, could, be"
45267,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.09375,"or, be, the"
45268,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.09375,"wet, market, in, wild, the, or"
45269,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.09375,"the, wild, animals"
45270,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.09375,"however,, in, were"
45271,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.09375,"the, outbreak, that"
45272,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.09375,"the, virus, market"
45273,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.09375,"in, the, was, outbreak, that, virus"
45274,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.09375,"a, of, that, the, or, in"
45275,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.09375,"it, that, a, the, of, or"
45276,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.09375,"it, was, in, a, with, the"
45277,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.09375,"the, be, market"
45278,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.09375,"isolated, from, showed, hosts, be, the"
45279,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.09375,"the, a, novel, coronavirus, that, with"
45280,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.09375,"of, the, to"
45281,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.09375,"the, of, evolutionary"
45282,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.09375,"the, to, a, for, is, was, that, by, and"
45283,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.09375,"the, a, that, to, by, and"
45284,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.09375,"and, transmission, of, to, another, be"
45285,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Scientific reports published so far include  

hosts, such as bats (28), pangolins (29), cats  

(11), and dogs (30)",0.09375,"as, pangolins, and"
45286,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.09375,"to, spillover, and"
45287,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.09375,"with, the, of, as, covs, and"
45288,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Coronaviruses are naturally hosted and developmentally 

formed by bats.",0.09375,"and, are, coronaviruses"
45289,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Coronaviruses are naturally hosted and developmentally 

formed by bats.",0.09375,"and, are, by"
45290,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.09375,"that, from, the"
45291,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.09375,"been, of, the"
45292,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.09375,"studies, to, that"
45293,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.09375,"studies, have, that"
45294,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.09375,"the, pangolin, of"
45295,"Bats have been reported as being the rich source of 

coronaviruses","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.09375,"bats, have, of"
45296,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.09375,"bat, is, shown"
45297,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.09375,"the, virus, covid-19"
45298,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.09375,"the, has, which"
45299,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.09375,"the, covid-19, which"
45300,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.09375,"bats, the, its"
45301,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",Many of these CoVs can infect several animal species as well,0.09375,"species, of, several"
45302,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",Many of these CoVs can infect several animal species as well,0.09375,"these, of, as"
45303,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",Many of these CoVs can infect several animal species as well,0.09375,"of, many, as"
45304,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",Many of these CoVs can infect several animal species as well,0.09375,"of, many, covs"
45305,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.09375,"a, that, virus"
45306,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.09375,"a, virus, from"
45307,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.09375,"human, to, animal"
45308,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.09375,"to, that, zoonotic"
45309,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.09375,"to, that, virus"
45310,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.09375,"are, to, humans"
45311,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.09375,"that, bat, in"
45312,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.09375,"their, bat, origin"
45313,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.09375,"been, to, in"
45314,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.09375,"from, the, to, virus, and, could, human, in, an"
45315,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.09375,"or, evidence, natural"
45316,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.09375,"a, and, has"
45317,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.09375,"and, that, a, evidence, suggests, or"
45318,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.09375,"that, is, not"
45319,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.09375,"is, and, sars-cov-2"
45320,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.09375,"in, probably, virus"
45321,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.09375,"that, it, to, an, animal, humans, by, of, is"
45322,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.09375,"to, be, of, another, transmission, and"
45323,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.09375,"virus, to, the"
45324,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.09375,"the, of, and, that, virus, to"
45325,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.09375,"the, that, virus"
45326,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.09375,"had, and, to, the, of, that"
45327,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",COVID-19 is a zoonotic virus,0.09375,"a, virus, covid-19"
45328,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.09375,"of, to, the, virus, covid-19, from"
45329,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.09375,"the, of, virus, from, with, to"
45330,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.09375,"the, and, pangolins,"
45331,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.09375,"as, the, many, birds,, such, and"
45332,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.09375,"coronavirus, in, the"
45333,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.09375,"the, that, viruses"
45334,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.09375,"the, of, be, to, and, reservoirs"
45335,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.09375,"the, of, highly"
45336,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.09375,"the, coronavirus, human"
45337,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.09375,"of, the, bat, and, sars-, with"
45338,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.09375,"has, and, with"
45339,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.09375,"to, the, of, and, from, bat"
45340,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.09375,"and, the, of, bat, to, as, related, that, close"
45341,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.09375,"of, that, the, bat, from, as"
45342,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.09375,"of, the, that, covid-19, and, approximately"
45343,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","no modifications were  

recorded for nonstructural proteins NSP7, NSP13  

and the structured and accessory proteins p6 and 8b.",0.09375,"the, and, were"
45344,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.09375,"with, in, of"
45345,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.09375,"with, of, in"
45346,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.09375,"sars-cov-2, natural, on, the, and, analysis"
45347,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.09375,"to, animal, in"
45348,"In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.09375,"in, to, human"
45349,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.09375,"host, sars-cov-2, in"
45350,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.09375,"to, human, ace2"
45351,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.09375,"and, bat, that, the, between, is"
45352,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.09375,"revealed, the, and"
45353,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.09375,"and, the, of, is, are, hosts"
45354,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.09375,"the, to, identical"
45355,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.09375,"and, sars-cov-2, the, between, in, with"
45356,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.09375,"that, a, sars-cov-2"
45357,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.09375,"that, a, bat"
45358,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.09375,"the, of, suggested, that, (order,, intermediate"
45359,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.09375,"a, on, were, of, in, the"
45360,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.09375,"with, the, and, that, sars-cov-2, of"
45361,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.09375,"of, to, the, in, indicate, that"
45362,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.09375,"viruses, to, sars-cov-2,, and, a, the"
45363,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.09375,"in, the, of, a, to, bat, coronaviruses, viruses, genome, similar, and, that"
45364,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.09375,"the, hosts, sars-cov-2"
45365,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.09375,"most, the, are"
45366,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Bats are natural hosts of many of the known  

coronaviruses",0.09375,"are, known, the"
45367,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.09375,"be, a, in, that, sars-cov-2, from"
45368,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.09375,"the, of, as, a, two, and"
45369,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.09375,"at, sars-cov-2, the, acid, of, receptor"
45370,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.09375,"the, of, (order,, suggested, that, intermediate"
45371,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.09375,"the, likely, to"
45372,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.09375,"the, which, has"
45373,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.09375,"the, of, mutations, and, that, a"
45374,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.09375,"with, that, of"
45375,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.09375,"that, to, with"
45376,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.09375,"a, that, the"
45377,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.09375,"of, the, these"
45378,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.09375,"a, of, analysis"
45379,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.09375,"the, to, have"
45380,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.09375,"the, bat, in"
45381,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.09375,"the, bat, was"
45382,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.09375,"at, the, of"
45383,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.09375,"origin, an, animal"
45384,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.09375,"that, the, reservoir"
45385,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.09375,"ace2, sars-cov-2, and"
45386,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.09375,"a, and, sars-cov-2"
45387,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.09375,"and, sars-cov-2, a"
45388,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.09375,"the, pangolin, for"
45389,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.09375,"of, on, the, and, in, many"
45390,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.09375,"have, been, as"
45391,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.09375,"of, has, the"
45392,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.09375,"of, sars-cov-2, ratg13"
45393,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.09375,"was, to, the"
45394,"In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.09375,"to, than, human"
45395,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.09375,"in, human, virus"
45396,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.09375,"virus, human, in"
45397,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.09375,"are, virus, strains"
45398,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.09375,"a, of, species, and, the, as"
45399,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.09375,"the, and, to, these, have, evolution"
45400,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.09375,"virus, strains, are"
45401,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K",0.09375,"to, human, than"
45402,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.09375,"has, a, and"
45403,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.09375,"has, the, bat"
45404,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.09375,"sars-cov-2, and, of, the, to, wild, in, for, zoonotic"
45405,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.09375,"in, the, and, to, sars-cov-2, of"
45406,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.09375,"with, covs, the, of, as, and"
45407,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.09375,"the, of, and, two, as, a"
45408,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.09375,"sars-cov-2, to, genome"
45409,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.09375,"sars-cov-2, in, host"
45410,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.09375,"in, the, a"
45411,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.09375,"sars-cov-2, to, the, for, in, wild, zoonotic, and, of"
45412,"expended to make the simple point 

that COVID-19 had a natural origin.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.09375,"to, the, had"
45413,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.09375,"sars-cov-2, in, to"
45414,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.09375,"the, into, to"
45415,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.09375,"that, in, the"
45416,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.09375,"in, the, of, a, to, study, with, found, that, from, years, species"
45417,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.09375,"sars-cov-2, with, similarity"
45418,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.09375,"in, of, a, found, that, virus"
45419,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.09375,"market, the, virus"
45420,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.09375,"the, with, market"
45421,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.09375,"has, to, ratg13"
45422,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","bats are also important reservoir species for a great 

range of coronaviruses",0.09375,"of, a, bats"
45423,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","bats are also important reservoir species for a great 

range of coronaviruses",0.09375,"for, a, also"
45424,"An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.09375,"an, of, species"
45425,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.09375,"of, sequence, that"
45426,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.09375,"that, of, protein"
45427,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.09375,"and, the, sars-cov-2,, from, in, bats"
45428,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.09375,"and, ratg13, in, is, the, to"
45429,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.09375,"a, amino, acid, to, in, the"
45430,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.09375,"with, sars-cov-2, in"
45431,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.09375,"the, in, a, as, of, and"
45432,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.09375,"the, of, a, and, species, as"
45433,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.09375,"between, sars-cov-2, and, with, the, in"
45434,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.09375,"to, the, that, between, and, be"
45435,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.09375,"have, the, evolution, to, and, these"
45436,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.09375,"to, the, that, has, been, and"
45437,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.09375,"in, found, to, suggesting, that, may"
45438,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.09375,"a, the, and, in, that, to"
45439,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.09375,"some, to, for, the, by, of, and, also, species"
45440,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.09375,"a, host, to"
45441,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.09375,"a, zoonotic, the"
45442,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.09375,"and, in, animal"
45443,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.09375,"sars-cov-2, in, with"
45444,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan",0.09375,"in, wuhan, animal"
45445,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.09375,"of, the, from, that, sars-cov-2, in"
45446,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.09375,"from, in, that, the, of, sars-cov-2"
45447,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.09375,"and, sars-cov-2, to, coronaviruses, in, a"
45448,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.09375,"the, and, of, coronaviruses, that, to"
45449,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.09375,"of, sars-cov-2, from, in, and, to"
45450,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.09375,"the, and, it, with, to, of"
45451,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.09375,"a, of, the, it, is, sars-cov-2"
45452,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.09375,"it, that, the, or, a, of"
45453,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.09375,"it, a, sars-cov-2, at, the, genome"
45454,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.09375,"and, species, are, or, bats, cave"
45455,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.09375,"and, species, to, the, reservoir, animal"
45456,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.09375,"the, many, such, as, and, birds,"
45457,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.09375,"bat, population, and, species, to, the"
45458,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.09375,"of, which, the"
45459,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.09375,"the, of, including"
45460,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.09375,"the, bats, for"
45461,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.09375,"the, to, bat, species, population, and"
45462,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.09375,"species, of, the"
45463,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.09375,"the, and, an"
45464,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.09375,"that, a, recombination, of, to, the"
45465,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.09375,"the, of, that, close, to, bat, as, and, related"
45466,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.09375,"of, the, in, a, similar, to, that, events, can"
45467,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.09375,"sars-cov-2, was, a, by, the, in"
45468,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.09375,"it, was, the, with, in, a"
45469,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.09375,"it, sars-cov-2, a, the, at, genome"
45470,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.09375,"are, viruses, of"
45471,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.09375,"the, of, when, to, closely, related"
45472,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.09375,"the, that, sars-cov-2."
45473,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","This suggests that the BANAL series may be able to directly infect  

humans.",0.09375,"that, to, the"
45474,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","This suggests that the BANAL series may be able to directly infect  

humans.",0.09375,"that, infect, to"
45475,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","This suggests that the BANAL series may be able to directly infect  

humans.",0.09375,"that, the, to, may, be, this"
45476,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","This suggests that the BANAL series may be able to directly infect  

humans.",0.09375,"that, be, the"
45477,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.09375,"the, from, is"
45478,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.09375,"of, a, viruses"
45479,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.09375,"the, viruses, to, have, closely, related, is, and, at"
45480,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.09375,"the, and, a, viruses, to, sars-cov-2,"
45481,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.09375,"in, as, bats"
45482,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.09375,"in, and, was"
45483,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.09375,"was, as, and"
45484,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.09375,"in, the, to, virus, closely, related"
45485,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.09375,"most, the, in"
45486,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.09375,"viral, of, the"
45487,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.09375,"a, the, in, to, with, sars-cov-2"
45488,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.09375,"and, that, the, covid-19, approximately, of"
45489,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.09375,"to, the, of, at, market, taken"
45490,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.09375,"or, wild, in, the, wet, market"
45491,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.09375,"had, to, for, by, the, of, that, in, a"
45492,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.09375,"of, a, virus, at, the, market, was, by, from"
45493,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.09375,"were, in, closely, related, to, sampled, the, animal, than"
45494,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.09375,"the, animal, at, market, was, than, that, in, and"
45495,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.09375,"and, the, virus, was, from, to, a, market, in"
45496,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.09375,"to, a, of, and, adapted, the"
45497,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.09375,"to, the, sequence, with, a, from"
45498,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.09375,"evidence, suggests, that, a, and, or"
45499,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.09375,"and, in, to, of, more, than"
45500,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.09375,"the, of, that, and, identical, to"
45501,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.09375,"that, in, the, virus, was, outbreak"
45502,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.09375,"that, a, virus, found, in, of"
45503,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.09375,"the, closely, related, to, when, of"
45504,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.09375,"that, in, and, the, virus, of"
45505,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.09375,"in, the, of, that, scale, as, a, used, bats"
45506,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.09375,"of, a, the, virus, to, which, bat, and, sars"
45507,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.09375,"in, the, of, that, its, as, a, human, used"
45508,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.09375,"the, virus, could, human, from, an, in, to, and"
45509,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.09375,"wiv, a, virus, that, with, the, in, its, bat"
45510,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.09375,"that, directly, from, a, bat, to, first, in, an"
45511,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.09375,"the, that, closest, with, at, of, virus, and, to"
45512,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.09375,"the, genome, of, and, bat, coronaviruses, that, a, in, viruses, similar, to"
45513,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.09375,"study, that, of, from, to, a, found, in, with, species, the, years"
45514,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.09375,"the, of, study, that, viruses, in, a, could, multiple, sars, and, to"
45515,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.09375,"the, earliest, wet, infected, were, at, as, by, collected"
45516,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.09375,"the, of, to, species, also, for, and, by, some"
45517,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.09375,"a, was, that, the, and, for, to, is, by"
45518,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.09375,"the, a, market, in, to, and"
45519,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.09375,"in, the, of, and, at, to, for, other, there, be, more, no"
45520,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.09375,"that, the, of, market, in, to, or, live, were, a, by, other"
45521,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.09375,"in, the, positive, and, a, of"
45522,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.09375,"samples, in, the, of, a, to"
45523,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.09375,"a, the, on, positive, of, and"
45524,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.09375,"on, in, the, of, a, were"
45525,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.09375,"evidence, to, a, of, the, and"
45526,The COVID-19 most likely developed from bat origin coronaviruses,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.09375,"the, covid-19, origin"
45527,"Bats are natural hosts of many of the known  

coronaviruses","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.09375,"are, the, known"
45528,"atural  

selection in an animal host before zoonotic  

transfer;","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.09375,"in, animal, zoonotic"
45529,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.09375,"the, in, and, that, this, a"
45530,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.09375,"the, covid-19, of, with, that, and"
45531,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.09375,"and, the, of, also, are, with, that, in, is"
45532,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.09375,"of, that, the, covid-19, is, these"
45533,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.09375,"that, the, zoonotic, and, be, of"
45534,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.09375,"study, be, the, of, sars-cov-2, and"
45535,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.09375,"of, the, huanan, market, from, taken"
45536,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.09375,"and, the, from, to, market, in"
45537,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.09375,"the, that, to, most, is, its, cause, into, sars-cov-2"
45538,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","expended to make the simple point 

that COVID-19 had a natural origin.",0.09375,"to, had, the"
45539,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.",0.09375,"the, host, zoonotic"
45540,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.09375,"in, the, results, and, to, of"
45541,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.09375,"and, in, to, the, of, natural"
45542,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.09375,"an, animal, origin"
45543,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.09375,"the, wiv, a, virus, that, with, bat, in, its"
45544,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.09375,"a, identity, with, sars-cov-2, in, the"
45545,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.09375,"in, sars-cov-2, with, bat, that, the"
45546,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.09375,"sars-cov-2, is, of"
45547,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.09375,"a, related, that"
45548,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.09375,"is, a, of"
45549,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.09375,"coronavirus, that, a"
45550,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.09375,"that, the, virus"
45551,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","atural  

selection in an animal host before zoonotic  

transfer;",0.09375,"animal, zoonotic, in"
45552,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.09375,"the, a, that, from, to, rhinolophus"
45553,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Malayan pangolins (Manis javanica)  

illegally imported into Guangdong province  

contain coronaviruses similar to SARS- 

CoV-22",0.09375,"coronaviruses, into, to"
45554,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.09375,"a, the, of, can, and, that"
45555,"According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.09375,"the, evolutionary, of"
45556,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.09375,"a, the, of, is, that, into"
45557,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.09375,"virus, probably, in"
45558,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.09375,"coronaviruses, rbds,, more, of, sars-cov-2, and"
45559,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.09375,"sars-cov-2, in, of, and, that, the"
45560,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","In the 

case of MERS, dromedaries were the principal host.",0.09375,"were, of, in"
45561,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.09375,"in, coronavirus, from, animals, to, and"
45562,COVID-19 is a zoonotic virus,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.09375,"covid-19, a, virus"
45563,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.09375,"in, the, of, a, to, study, viruses, could, and, that, sars, multiple"
45564,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.09375,"showed, and, identity, to, in, the"
45565,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.09375,"the, to, cov"
45566,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.09375,"the, which, covid-19"
45567,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.09375,"evidence, the, and, that, to, from"
45568,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",The COVID-19 most likely developed from bat origin coronaviruses,0.09375,"the, most, origin"
45569,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",The COVID-19 most likely developed from bat origin coronaviruses,0.09375,"likely, the, bat"
45570,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.09375,"the, of, that, from, bat, as"
45571,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.09375,"the, is, that, of, covid-19, these"
45572,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.09375,"genomic, of, to"
45573,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.09375,"suggests, the, intermediate"
45574,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.09375,"humans, to, are"
45575,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.09375,"to, covs, in"
45576,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.09375,"to, that, originated"
45577,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.09375,"in, be, that"
45578,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.09375,"the, market, be"
45579,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.09375,"to, the, be"
45580,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.09375,"in, of, have, the, that, was"
45581,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.09375,"the, covid-19, to, and, suggesting, that"
45582,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.09375,"that, the, of, suggesting, have, to"
45583,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.09375,"the, of, that, have, between, and"
45584,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.09375,"have, the, between, and, of, that"
45585,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.09375,"in, two, of, guangxi, and, have"
45586,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.09375,"the, in, associated"
45587,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.09375,"bats, a, as, the, of, in"
45588,Many of these CoVs can infect several animal species as well,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.09375,"of, these, as"
45589,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.09375,"species, the, of"
45590,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.09375,"of, and, the, or, in, bats"
45591,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.09375,"and, of, between, in, the, viruses"
45592,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.09375,"the, intermediate, host"
45593,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.09375,"on, from, bat, of, virus, and"
45594,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.09375,"are, or, species, bats, cave, and"
45595,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.09375,"was, the, case"
45596,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.09375,"the, acid, of, sars-cov-2, at, receptor"
45597,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.09375,"were, because, in"
45598,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.",0.09375,"viruses, of, their"
45599,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.09375,"wild, animals, the"
45600,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.09375,"is, the, covid-19"
45601,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.09375,"the, of, and, that, a, this"
45602,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.09375,"and, the, that, of, this, a"
45603,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.09375,"and, this, the, of, that, a"
45604,"bats are also important reservoir species for a great 

range of coronaviruses","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.09375,"also, for, a"
45605,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.09375,"a, that, the, and, to, by"
45606,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.09375,"from, a, rhinolophus, to, the, that"
45607,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.09375,"the, isolated, from, showed, be, hosts"
45608,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.09375,"to, a, amino, acid, in, the"
45609,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.09375,"a, identity, with, the, sars-cov-2, in"
45610,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.09375,"the, showed, identity, to, and, in"
45611,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.09375,"sars-cov-2, from, a, to, in, intermediate"
45612,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.09375,"the, sars-cov-2, has, with, and, to"
45613,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.09375,"the, showed, identity, to, sars-cov-2, from"
45614,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.09375,"the, associated, in"
45615,"Bats have been reported as being the rich source of 

coronaviruses","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.09375,"as, of, coronaviruses"
45616,Many of these CoVs can infect several animal species as well,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.09375,"many, of, as"
45617,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.09375,"the, virus, of"
45618,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.09375,"a, of, we, likely, was, analysis"
45619,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.09375,"of, was, natural"
45620,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.09375,"analysis, of, a"
45621,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.09375,"the, of, that, have, been, to"
45622,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.09375,"are, the, animal"
45623,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.09375,"the, coronavirus, in"
45624,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.09375,"are, the, most"
45625,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.09375,"with, the, in"
45626,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.09375,"the, with, by"
45627,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.09375,"from, first, to, a, that, bat, directly, in, an"
45628,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.09375,"from, a, sars-cov-2, intermediate, to, in"
45629,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.09375,"a, but, of"
45630,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.09375,"that, the, and, may, of, to"
45631,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.09375,"that, the, had, of, and, to"
45632,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.09375,"a, of, in, that, for, by, had, the, to"
45633,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.09375,"suggested, the, of, sars-cov-2, and, intermediate"
45634,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.09375,"the, case, as"
45635,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.09375,"the, was, from"
45636,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.09375,"the, case, was"
45637,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.09375,"the, an, cov"
45638,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.09375,"sars-cov-2, the, genome"
45639,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.09375,"the, identical, to"
45640,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.09375,"sars-cov-2, the, genetic, of, that, it"
45641,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.09375,"these, are, the, that, or, for"
45642,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.09375,"hypothesis, the, of"
45643,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.09375,"has, ratg13, to"
45644,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.09375,"that, made, sars-cov-2"
45645,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.09375,"to, that, and"
45646,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.09375,"to, ratg13, and, that, sars-cov-2, share"
45647,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.09375,"of, coronaviruses, rbds,, and, more, sars-cov-2"
45648,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.09375,"ratg13, sars-cov-2, that, bats, are, more"
45649,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.09375,"sars-cov-2, of, bat"
45650,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.09375,"known, be, the"
45651,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.09375,"viruses, the, that"
45652,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.09375,"be, the, most"
45653,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.09375,"that, and, be, to, the, between"
45654,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.09375,"has, been, the, and, to, that"
45655,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.09375,"of, from, we, sars-cov-2, and, their"
45656,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.09375,"and, sars-cov-2, of, bat, ratg13, closest"
45657,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.09375,"the, of, these"
45658,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.09375,"may, be, the, natural, of, and"
45659,"This suggests that the BANAL series may be able to directly infect  

humans.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.09375,"this, that, the, may, be, to"
45660,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.09375,"evidence, to, of, the, and, that"
45661,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.09375,"the, of, and, that, this, natural"
45662,"Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.09375,"or, the, be"
45663,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.09375,"the, its, bats"
45664,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.09375,"the, sars-cov-2, hosts"
45665,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.09375,"and, sars-cov-2, bats"
45666,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.09375,"and, are, that"
45667,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.09375,"sars-cov-2, and, probable"
45668,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.09375,"that, and, for"
45669,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.09375,"bats, the, for"
45670,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.09375,"that, the, bats, are, likely, hosts"
45671,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.09375,"bat, similar, to"
45672,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.09375,"a, the, bats"
45673,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.09375,"the, that, reservoir"
45674,Many of these CoVs can infect several animal species as well,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.09375,"many, of, covs"
45675,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.09375,"a, of, to, the, which, bat, and, sars, virus"
45676,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.09375,"bat, to, covs."
45677,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.09375,"is, also, sars-cov-2, a, the, in"
45678,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.09375,"a, to, in, sars-cov-2, the, and"
45679,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.09375,"of, and, the, in, viruses, between"
45680,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.09375,"of, and, two, have, in, guangxi"
45681,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.09375,"that, the, of, recombination, a, to"
45682,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.09375,"the, that, a, of, mutations, and"
45683,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.09375,"a, and, this, in, the, that"
45684,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.09375,"the, of, this, that, a, in"
45685,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.09375,"shown, is, bat"
45686,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.09375,"to, bat, covs."
45687,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.09375,"is, the, that"
45688,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.09375,"are, that, to, and, viruses, in"
45689,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.09375,"the, that, these, are, or, for"
45690,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.09375,"bats, are, more, that, sars-cov-2, ratg13"
45691,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.09375,"the, that, viruses, in, and, to"
45692,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.09375,"the, and, in, to, that, bat"
45693,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.09375,"that, with, the, sars-cov-2, in, bat"
45694,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.09375,"to, the, that, sars-cov-2, as, of"
45695,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.09375,"of, in, and, to, results, the"
45696,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.09375,"of, sars-cov-2, and, closest, bat, ratg13"
45697,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.09375,"of, the, pangolin"
45698,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.09375,"of, the, bat"
45699,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.09375,"bats, are, for, the, in, that"
45700,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.09375,"origin, are, the"
45701,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.09375,"bat, sequences, and"
45702,hese close genetic relations suggest that they all have their ecological origin in bat populations,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.09375,"their, origin, bat"
45703,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.09375,"and, probable, sars-cov-2"
45704,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.09375,"have, that, sars-cov-2"
45705,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.09375,"sars-cov-2, the, of, that, have, to"
45706,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.09375,"to, the, sars-, and, may, for"
45707,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.09375,"virus, from, bat, of, and, on"
45708,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.09375,"the, and, in, these, bat, of"
45709,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.09375,"with, that, to"
45710,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.09375,"that, with, to"
45711,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.09375,"the, and, with"
45712,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.09375,"by, the, with"
45713,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.09375,"and, the, from"
45714,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.09375,"the, revealed, and"
45715,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.09375,"a, the, from, and, in, both"
45716,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.09375,"a, of, the, that, and, are"
45717,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.09375,"are, the, sars-cov-2, to, in, and"
45718,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.09375,"the, residues, to"
45719,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.09375,"in, the, of, that, virus, and"
45720,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.09375,"the, to, virus, that, with, and, of, closest, at"
45721,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.09375,"and, with, sars-cov-2, has, to, the"
45722,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.09375,"that, be, in"
45723,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.09375,"in, the, and, that, of, bat"
45724,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.09375,"and, in, be, that, the, of"
45725,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.09375,"from, showed, identity, sars-cov-2, to, the"
45726,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.09375,"the, that, to, in, is, mutations, of, sars-cov-2, at"
45727,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.09375,"intermediate, host, the"
45728,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.09375,"the, of, to, be, that, sars-cov-2"
45729,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.09375,"that, the, sars-cov-2."
45730,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.09375,"sars-cov-2, very, to"
45731,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.09375,"the, of, most"
45732,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.09375,"and, the, be, of, sars-cov-2, study"
45733,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.09375,"intermediate, and, the, of, suggested, sars-cov-2"
45734,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.09375,"the, and, virus"
45735,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.09375,"and, an, the"
45736,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.09375,"an, the, cov"
45737,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.09375,"the, of, in, that, this, a"
45738,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.09375,"sars-cov-2, a, from, be, that, in"
45739,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.09375,"to, of, the, and, it, with"
45740,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.09375,"in, of, china"
45741,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.09375,"the, are, for"
45742,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.09375,"are, the, origin"
45743,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.09375,"found, in, to, suggesting, that, may"
45744,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.09375,"large, of, that, to, in, zoonotic"
45745,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.09375,"the, of, animal, that, at, in"
45746,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.09375,"the, of, to, similar, a, that, in, events, can"
45747,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.09375,"that, a, of, similar, to, the"
45748,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.09375,"the, and, are, very, to, sars-"
45749,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.09375,"the, to, coronavirus, and, that, very"
45750,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.09375,"hosts, and, are, the, of, is"
45751,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.09375,"of, in, natural, and, to, the"
45752,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.09375,"the, that, bats, are, likely, hosts"
45753,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.09375,"in, be, that, the, and, of"
45754,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.09375,"sars-cov-2, and, very, to, the, of"
45755,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.09375,"and, bat, to, the, that, in"
45756,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.09375,"in, the, bat, of, these, and"
45757,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.09375,"highly, homologous, coron-, and, of, coronaviruses"
45758,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.09375,"and, coron-, highly, homologous, coronaviruses, of"
45759,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.09375,"to, the, have, of, suggesting, that"
45760,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.09375,"on, the, analysis, sars-cov-2, natural, and"
45761,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.09375,"the, many, in, and, on, of"
45762,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.09375,"96%, to, sars-cov-2"
45763,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.09375,"and, to, the, of, very, sars-cov-2"
45764,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.09375,"a, sars-cov-2, the"
45765,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.09352518,"the, center, from, on, and, in, with, of, a, according, to, positive, at"
45766,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.09352518,"center, and, with, from, to, at, the, in, of, according, on, a, positive"
45767,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.093457944,"than, animals, of, that, for, virus, were, infected, coronavirus, and"
45768,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.093457944,"in, a, of, to, have, the, virus, that, covid-19, for"
45769,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.093457944,"from, the, was, also, a, virus, that, by, in, its"
45770,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.093457944,"of, covid-19, for, to, a, virus, have, that, in, the"
45771,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.093457944,"the, of, from, that, for, virus, to, a, coronavirus, and"
45772,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.093457944,"the, was, a, live, that, with, used, as, in, of"
45773,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.093457944,"of, than, animals, and, that, for, virus, were, infected, coronavirus"
45774,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.093457944,"the, virus, for, a, of, to, that, coronavirus, from, and"
45775,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.093457944,"or, the, species, of, to, as, civets, and, raccoon, in"
45776,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.093457944,"in, a, of, for, were, found, to, be, that, zoonotic"
45777,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.093457944,"and, also, a, of, in, the, viral, for, viruses, to"
45778,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.093457944,"also, that, was, from, a, by, the, virus, its, in"
45779,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.093457944,"was, that, the, with, in, live, used, as, a, of"
45780,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.093457944,"the, of, that, viruses, in, a, multiple, sars, and, to"
45781,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.093457944,"the, of, sars-cov-2, to, is, likely, a, or, that, this"
45782,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.093457944,"of, that, the, covid-19, is, a, animal, or, for, infections"
45783,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.093457944,"that, by, a, of, with, to, and, the, for, sars-cov-2"
45784,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.093457944,"the, of, a, or, to, that, this, is, sars-cov-2, likely"
45785,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.093457944,"the, to, in, a, of, viruses, sars, that, multiple, and"
45786,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.093457944,"the, for, of, a, or, that, covid-19, infections, is, animal"
45787,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.093457944,"the, of, raccoon, and, civets, species, in, or, as, to"
45788,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.093457944,"the, of, a, viruses, in, to, and, also, for, viral"
45789,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.093457944,"with, the, and, for, of, a, to, that, sars-cov-2, by"
45790,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.093457944,"to, were, for, zoonotic, be, a, in, of, that, found"
45791,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.093333333,"of, scientific, the, that, sars-cov-2, a, virus"
45792,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.093333333,"be, a, bat, to, of, and, some"
45793,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.093333333,"a, of, some, have, and, the, to"
45794,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.093333333,"a, in, the, is, to, of, found"
45795,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.093333333,"and, the, be, that, its, of, sars-cov-2"
45796,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.093333333,"the, of, coronavirus, that, to, as, and"
45797,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.093333333,"of, the, in, a, to, that, can"
45798,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.093333333,"and, an, to, the, of, a, animal"
45799,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.093333333,"the, is, of, to, and, a, an"
45800,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.093333333,"with, a, to, any, and, the, in"
45801,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.093333333,"sars-cov-2, on, and, with, to, sars-, cov-2"
45802,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.093333333,"a, and, were, of, which, in, the"
45803,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.093333333,"in, the, and, that, of, huanan, market"
45804,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.093333333,"in, the, of, as, a, to, and"
45805,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.093333333,"sars-cov-2, of, the, to, sars-, cov-2, in"
45806,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.093333333,"the, of, virus, to, sars-cov-2,, as, genetic"
45807,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.093333333,"have, the, of, virus, is, to, that"
45808,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.093333333,"found, in, the, of, that, but, virus"
45809,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.093333333,"a, is, in, the, that, it, not"
45810,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.093333333,"the, of, which, to, in, market, virus"
45811,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.093333333,"of, cases, to, other, and, the, in"
45812,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.093333333,"the, animal, to, have, and, which, humans"
45813,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.093333333,"at, the, of, a, there, was, no"
45814,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.093333333,"and, to, be, the, sars-, is, natural"
45815,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.093333333,"of, natural, on, the, and, with, high"
45816,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.093333333,"for, the, and, host, that, a, to"
45817,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.093333333,"bats, of, and, which, to, as, cov,"
45818,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.093333333,"of, to, have, the, virus, that, is"
45819,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.093333333,"the, of, is, virus, to, that, genetic"
45820,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.093333333,"and, to, the, of, that, sars-cov-2, have"
45821,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.093333333,"bats, the, of, to, in, isolated, also"
45822,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.093333333,"animal, to, another, species, close, and, humans"
45823,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.093333333,"in, december, the, of, virus, from, and"
45824,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.093333333,"the, of, sars-cov, and, coronaviruses, a, to"
45825,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.093333333,"the, of, a, could, human, and, to"
45826,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.093333333,"be, a, to, bats, of, and, as"
45827,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.093333333,"the, and, a, to, coronaviruses, of, group."
45828,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.093333333,"coronavirus, as, the, of, and, that, to"
45829,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.093333333,"bat, a, that, this, in, virus, is"
45830,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.093333333,"coronaviruses, sars-cov, and, a, to, the, of"
45831,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.093333333,"that, are, the, of, and, viruses, in"
45832,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.093333333,"to, coronavirus, in, bats, and, that, a"
45833,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.093333333,"the, of, in, found, virus, that, but"
45834,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.093333333,"the, of, as, a, to, human, and"
45835,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.093333333,"to, the, of, and, that, these, emergence"
45836,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.093333333,"to, sars-cov-2, in, the, and, that, with"
45837,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.093333333,"on, the, other, in, and, that, than"
45838,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.093333333,"that, and, sars-cov-2, to, the, in, with"
45839,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.093333333,"the, and, have, animal, which, to, humans"
45840,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.093333333,"close, humans, and, to, another, animal, species"
45841,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.093333333,"a, virus, that, is, in, this, bat"
45842,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.093333333,"the, genetic, of, virus, is, to, that"
45843,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.093333333,"the, that, a, virus, found, in, additional"
45844,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.093333333,"the, have, a, which, to, and, at"
45845,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.093333333,"as, the, of, to, genetic, sars-cov-2,, virus"
45846,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.093333333,"the, reported, to, that, in, with, of"
45847,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.093333333,"a, in, the, that, animal, or, for"
45848,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.093333333,"that, antibodies, with, the, of, suggesting, to"
45849,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.093333333,"a, that, the, and, for, to, host"
45850,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.093333333,"the, and, of, sequence, virus, to, that"
45851,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.093333333,"of, the, virus, from, in, december, and"
45852,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.093333333,"to, a, of, an, animal, and, the"
45853,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.093333333,"there, no, at, the, was, of, a"
45854,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.093333333,"is, to, a, of, an, and, the"
45855,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.093333333,"a, that, the, covid-19, is, of, and"
45856,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.093333333,"in, the, a, to, any, and, with"
45857,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.093333333,"other, the, of, cases, and, in, to"
45858,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.093333333,"a, of, the, and, in, which, were"
45859,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.093333333,"the, of, its, be, that, and, sars-cov-2"
45860,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.093333333,"from, a, its, in, the, that, it"
45861,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.093333333,"the, of, and, huanan, market, that, in"
45862,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.093333333,"in, a, to, the, that, is, from"
45863,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.093333333,"a, the, in, it, that, not, is"
45864,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.093333333,"the, it, that, its, in, from, a"
45865,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.093333333,"and, from, in, to, coronavirus, is, very"
45866,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.093333333,"the, in, found, a, virus, additional, that"
45867,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.093333333,"and, a, to, the, could, of, human"
45868,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.093333333,"a, and, to, that, coronavirus, in, bats"
45869,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.093333333,"the, of, and, that, in, viruses, are"
45870,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.093333333,"in, china, that, the, of, present, bats"
45871,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.093333333,"of, in, that, with, the, reported, to"
45872,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.093333333,"and, some, to, be, a, of, bat"
45873,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.093333333,"and, a, to, bats, be, of, as"
45874,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.093333333,"as, a, of, from, to, bat, and"
45875,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.093333333,"the, of, in, also, to, isolated, bats"
45876,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.093333333,"of, to, the, market, in, which, virus"
45877,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.093333333,"to, and, have, a, at, the, which"
45878,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.093333333,"the, is, that, of, and, a, covid-19"
45879,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.093333333,"the, and, some, have, to, a, of"
45880,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.093333333,"a, from, bat, to, of, and, as"
45881,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.093333333,"a, by, from, that, the, to, of"
45882,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.093333333,"sars-cov-2, of, a, virus, scientific, that, the"
45883,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.093333333,"have, the, sars-cov-2, and, of, to, that"
45884,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.093333333,"that, the, of, sars-cov-2, and, this, more"
45885,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.093333333,"the, to, a, of, is, found, in"
45886,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.093333333,"present, that, bats, the, of, in, china"
45887,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.093333333,"the, a, of, that, from, to, by"
45888,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.093333333,"that, and, other, than, on, the, in"
45889,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.093333333,"that, more, the, sars-cov-2, this, of, and"
45890,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.093333333,"sars-cov-2, of, the, and, to, sars-, cov-2"
45891,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.093333333,"sars-cov-2, of, for, that, in, and, the"
45892,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.093333333,"a, in, that, animal, for, the, or"
45893,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.093333333,"bats, as, to, which, of, cov,, and"
45894,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.093333333,"a, the, of, can, in, that, to"
45895,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.093333333,"coronavirus, is, and, very, from, to, in"
45896,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.093333333,"coronaviruses, and, a, to, the, group., of"
45897,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.093333333,"of, that, antibodies, with, the, suggesting, to"
45898,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.093333333,"sars-cov-2, with, sars-, cov-2, on, and, to"
45899,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.093333333,"in, sars-, cov-2, the, of, sars-cov-2, to"
45900,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.093333333,"the, on, natural, of, high, and, with"
45901,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.093333333,"to, sars-, cov-2, the, of, and, sars-cov-2"
45902,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.093220339,"with, the, and, for, of, a, to, that, in, is, be"
45903,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.093220339,"the, of, closely, related, is, by, in, wiv, to, sars, that"
45904,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.093220339,"this, that, a, the, virus, was, of, in, have, to, live"
45905,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.093220339,"evidence, that, were, in, the, market, a, or, animals, of, “the"
45906,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.093220339,"the, of, a, as, with, genome, were, and, from, it, its"
45907,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.093220339,"the, that, wiv, to, closely, related, sars, in, is, by, of"
45908,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.093220339,"in, a, of, to, have, the, virus, that, was, this, live"
45909,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.093220339,"with, the, of, were, as, a, it, its, genome, from, and"
45910,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.093220339,"that, the, of, market, in, or, “the, animals, were, evidence, a"
45911,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.093220339,"a, for, the, of, is, and, be, in, with, that, to"
45912,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.093023256,"are, to, sars-cov-2, and"
45913,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.093023256,"a, sars-cov-2, sars-cov, and"
45914,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.093023256,"sars-cov-2, and, sars-cov, bat"
45915,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.093023256,"sars-cov-2, to, which, in"
45916,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.093023256,"are, a, sars-cov, and"
45917,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.093023256,"of, are, coronaviruses, in"
45918,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.093023256,"of, a, species, viruses"
45919,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.093023256,"the, from, bats, in"
45920,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.093023256,"the, in, from, horseshoe"
45921,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.093023256,"the, are, to, of, reservoir, bats, animal, and"
45922,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.093023256,"and, sars-cov, bat, in"
45923,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.093023256,"of, to, in, china,"
45924,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.093023256,"to, sars-cov-2, in, of"
45925,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.093023256,"bats, and, in, china,"
45926,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.093023256,"of, to, which, in"
45927,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.093023256,"were, of, from, and"
45928,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.093023256,"to, whole, genome, in"
45929,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.093023256,"and, a, is, for"
45930,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.093023256,"may, the, of, and"
45931,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.093023256,"the, of, spillover, into"
45932,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.093023256,"may, from, virus, bat"
45933,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.093023256,"the, spillover, from, and"
45934,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.093023256,"by, that, sars-cov-2, a"
45935,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.093023256,"it, that, sars-cov-2, of"
45936,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.093023256,"virus, the, covid-19, to, and, that, human, sars-cov-2"
45937,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.093023256,"to, that, sars-cov-2, has, the, virus, origin, of"
45938,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.093023256,"the, of, have, a, which, to, in, and"
45939,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.093023256,"the, to, a, laboratory"
45940,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.093023256,"virus, is, that, and"
45941,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.093023256,"virus, and, other, with"
45942,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.093023256,"is, sars-cov-2, a, virus"
45943,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.093023256,"to, with, the, sars-cov-2"
45944,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.093023256,"the, to, as, bat"
45945,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.093023256,"the, a, and, of"
45946,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.093023256,"and, of, viruses, including"
45947,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.093023256,"sars-cov-2, covid-19, to, human, virus, that, and, the"
45948,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.093023256,"to, the, sequence, sars-cov-2"
45949,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.093023256,"the, ratg13, to, sars-cov-2"
45950,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.093023256,"that, the, covid-19, and"
45951,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.093023256,"and, which, that, in"
45952,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.093023256,"observed, in, that, as"
45953,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.093023256,"and, with, of, sars-cov-2"
45954,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.093023256,"the, in, genome, to"
45955,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.093023256,"to, of, are, sars-cov-2"
45956,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.093023256,"the, reservoirs, and, have"
45957,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.093023256,"the, in, of, that"
45958,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.093023256,"the, in, that, bats"
45959,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.093023256,"the, its, in, of"
45960,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.093023256,"the, zoonotic, as, and"
45961,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.093023256,"have, the, of, than"
45962,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.093023256,"zoonotic, as, the, more"
45963,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.093023256,"is, that, a, the"
45964,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.093023256,"the, of, were, as"
45965,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.093023256,"pangolins, in, the, of"
45966,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.093023256,"the, from, for, hosts"
45967,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.093023256,"to, of, from, sars-cov-2"
45968,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.093023256,"the, to, for, from"
45969,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.093023256,"sars-cov-2, from, to, intermediate"
45970,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.093023256,"the, as, in, and"
45971,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.093023256,"the, only, in, china"
45972,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.093023256,"in, china,, to, of"
45973,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.093023256,"origin, in, animal, zoonotic"
45974,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.093023256,"the, this, origin, of"
45975,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.093023256,"to, in, wet, a, were, animal, and, market"
45976,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.093023256,"the, of, to, an"
45977,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.093023256,"the, of, and, may"
45978,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.093023256,"of, the, bats, and"
45979,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.093023256,"be, of, and, bats"
45980,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.093023256,"of, and, the, bats"
45981,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.093023256,"and, of, important, the"
45982,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.093023256,"into, the, that, to"
45983,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.093023256,"that, and, hosts, for"
45984,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.093023256,"the, sars-cov-2, through, of"
45985,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.093023256,"in, to, which, the"
45986,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.093023256,"the, to, sequence, sars-cov-2"
45987,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.093023256,"to, sars-cov-2, the, origin"
45988,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.093023256,"to, sars-cov-2,, which, the"
45989,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.093023256,"and, to, the, other"
45990,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.093023256,"the, and, was, to"
45991,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.093023256,"to, and, bats,, in"
45992,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.093023256,"is, in, the, that"
45993,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.093023256,"that, natural, for, the"
45994,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","civet cats and raccoon dogs  

are the intermediate hosts",0.093023256,"and, intermediate, hosts, the"
45995,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.093023256,"the, bats, and, to"
45996,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.093023256,"to, the, sars-cov-2, and"
45997,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.093023256,"sars-cov-2, has, in, humans"
45998,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.093023256,"bats, in, to, be"
45999,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.093023256,"is, sars-cov-2, to, through"
46000,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.093023256,"this, in, the, of"
46001,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.093023256,"and, that, in, which"
46002,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.093023256,"and, by, the, in"
46003,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.093023256,"the, by, a, and"
46004,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.093023256,"the, by, a, virus"
46005,"Bats have been reported as being the rich source of 

coronaviruses","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.093023256,"have, been, as, coronaviruses"
46006,Many of these CoVs can infect several animal species as well,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.093023256,"several, animal, species, as"
46007,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.093023256,"that, from, the, of"
46008,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.093023256,"the, of, from, sars-cov-2"
46009,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.093023256,"the, natural, to, of"
46010,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.093023256,"are, that, the, sars-cov-2"
46011,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.093023256,"only, could, the, that"
46012,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.093023256,"and, that, natural, the"
46013,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.093023256,"that, could, sars-cov-2, are"
46014,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.093023256,"and, of, at, the"
46015,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.093023256,"of, was, the, these"
46016,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.093023256,"the, of, into, spillover"
46017,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.093023256,"with, other, coronaviruses,, sars-cov-2"
46018,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.093023256,"closely, related, sars-cov-2, and"
46019,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.093023256,"of, sars-cov-2, from, bats"
46020,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.093023256,"the, from, at, that"
46021,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.093023256,"that, the, bat, at"
46022,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.093023256,"the, humans, intermediate, of"
46023,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.093023256,"intermediate, host, humans, the"
46024,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.093023256,"sars-cov-2, the, at, of"
46025,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.093023256,"the, of, from, zoonotic"
46026,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.093023256,"the, that, be, animals"
46027,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.093023256,"the, are, that, to"
46028,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.093023256,"and, the, at, of"
46029,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.093023256,"at, of, in, and"
46030,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.093023256,"is, a, and, the"
46031,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.093023256,"is, in, the, with"
46032,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.093023256,"and, of, with, at"
46033,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.093023256,"the, from, a, market"
46034,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.093023256,"the, of, virus, by"
46035,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.093023256,"of, and, the, animal"
46036,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.093023256,"the, coronavirus, in, and"
46037,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.093023256,"the, most, hosts, of"
46038,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.093023256,"coronavirus, in, the, of"
46039,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.093023256,"were, related, to, in"
46040,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.093023256,"nearly, identical, a, and"
46041,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.093023256,"were, from, of, and"
46042,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.093023256,"and, of, at, in"
46043,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.093023256,"of, sars-cov-2, and, two"
46044,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.093023256,"from, of, in, sars-cov-2"
46045,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.093023256,"the, in, and, very"
46046,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.093023256,"that, a, spillover, from"
46047,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.093023256,"sars-cov-2, a, that, from"
46048,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.093023256,"zoonotic, spillover, sars-cov-2, a"
46049,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.093023256,"a, zoonotic, spillover, that"
46050,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.093023256,"with, that, sars-cov-2, a"
46051,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.093023256,"that, the, a, in"
46052,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.093023256,"that, the, of, in, to, animals, have, a"
46053,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.093023256,"he, of, has, been, that, the, a, origin."
46054,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.093023256,"it, is, that, the, for, as, to, a"
46055,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.093023256,"the, are, of, genetic, laboratory, they, as, for"
46056,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.093023256,"to, the, of, and, as, for, are, more"
46057,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.093023256,"in, evidence, that, or"
46058,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.093023256,"the, is, that, have, in, of, to, similarly,, by, and, not, known"
46059,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.093023256,"the, sars-cov-2, with, be"
46060,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.093023256,"be, the, sars-cov-2, present"
46061,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.093023256,"the, to, in, genome"
46062,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.093023256,"a, the, market, in"
46063,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.093023256,"the, and, a, in, that, not, of, but"
46064,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.093023256,"to, that, evidence, is"
46065,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.093023256,"is, to, originated, in"
46066,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.093023256,"of, the, market, at, an, to, samples, evidence, infected, for, that, taken"
46067,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.093023256,"and, of, such, as"
46068,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.093023256,"the, was, and, about"
46069,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.093023256,"a, the, with, was, on, and, january, to"
46070,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.093023256,"on, and, that, bat"
46071,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.093023256,"the, bat, coronavirus, to"
46072,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.093023256,"this, the, that, virus"
46073,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.093023256,"from, the, virus, and"
46074,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.093023256,"that, a, to, and"
46075,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.093023256,"species, to, of, and"
46076,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.093023256,"that, and, to, of"
46077,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.093023256,"to, of, zoonotic, a"
46078,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.093023256,"that, infect, and, in"
46079,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.093023256,"and, can, which, that"
46080,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.093023256,"and, human, that, origin"
46081,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.093023256,"that, and, cov, which"
46082,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.093023256,"was, the, and, host"
46083,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.093023256,"from, is, to, human"
46084,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.093023256,"to, very, the, bat"
46085,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.093023256,"was, the, to, host"
46086,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.093023256,"that, the, this, virus"
46087,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.093023256,"had, been, of, the"
46088,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.093023256,"of, by, the, around"
46089,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.093023256,"the, of, that, sars-cov,"
46090,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.093023256,"and, the, is, transmitted"
46091,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.093023256,"the, that, bats, virus"
46092,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.093023256,"be, that, the, and"
46093,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.093023256,"has, a, genome, to"
46094,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.093023256,"with, the, a, from"
46095,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.093023256,"from, with, sars-cov-2, the"
46096,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.093023256,"and, the, from, to"
46097,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.093023256,"and, the, of, infected, to, similar, with, can"
46098,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.093023256,"with, the, from, bat"
46099,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.093023256,"sars-cov-2, to, originated, the"
46100,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.093023256,"of, the, between, and"
46101,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.093023256,"the, and, of, is"
46102,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.093023256,"and, transmitted, to, humans"
46103,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.093023256,"the, was, that, animal"
46104,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.093023256,"to, from, and, the"
46105,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.093023256,"the, and, from, a"
46106,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.093023256,"the, most, to, of"
46107,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.093023256,"virus, is, transmitted, to"
46108,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.093023256,"they, bats, in, the"
46109,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.093023256,"was, are, to, and"
46110,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.093023256,"virus, the, was, that"
46111,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.093023256,"that, of, the, part"
46112,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.093023256,"the, was, that, of"
46113,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.093023256,"at, is, the, that"
46114,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.093023256,"the, that, natural, and"
46115,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.093023256,"the, likely, to, and"
46116,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.093023256,"and, humans, in, the"
46117,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.093023256,"that, to, in, humans"
46118,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.093023256,"in, to, origin, that"
46119,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.093023256,"the, in, and, was"
46120,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.093023256,"the, was, about, and"
46121,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.093023256,"december, and, was, the"
46122,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.093023256,"the, with, sars-like, bat"
46123,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.093023256,"is, the, that, bats"
46124,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.093023256,"the, may, be, host"
46125,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.093023256,"studies, is, to, be"
46126,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.093023256,"from, in, the, may"
46127,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.093023256,"to, december, 2019,, had, by, and, was, the"
46128,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.093023256,"the, and, but, not"
46129,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.093023256,"analysis, that, the, bat"
46130,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.093023256,"the, in, seafood, market"
46131,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.093023256,"that, the, source, of"
46132,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.093023256,"the, from, hosts, for"
46133,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.093023256,"at, that, the, from"
46134,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.093023256,"that, isolated, at, market"
46135,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.093023256,"be, the, suggesting, that"
46136,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.093023256,"that, be, hosts, for"
46137,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.093023256,"with, bat, sars-like, the"
46138,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.093023256,"identical, to, the, human"
46139,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.093023256,"the, was, host, and"
46140,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.093023256,"the, host, was, to"
46141,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.093023256,"the, is, also, to"
46142,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.093023256,"the, is, that, for, to, by, and, a"
46143,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.093023256,"for, and, to, the"
46144,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.093023256,"the, for, sars-cov, and"
46145,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.093023256,"the, of, it, from"
46146,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.093023256,"of, are, bat, the"
46147,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.093023256,"of, it, that, bat"
46148,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.093023256,"sars-cov-2, that, have, to"
46149,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.093023256,"the, from, a, in"
46150,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.093023256,"the, of, from, viruses"
46151,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.093023256,"the, of, from, a"
46152,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.093023256,"on, that, bat, and"
46153,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.093023256,"and, that, of, bat"
46154,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.093023256,"that, and, bat, is"
46155,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.093023256,"that, most, bat, and"
46156,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",Many of these CoVs can infect several animal species as well,0.093023256,"animal, as, several, species"
46157,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.093023256,"to, from, virus, human"
46158,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.093023256,"to, is, virus, transmitted"
46159,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.093023256,"that, a, virus, to"
46160,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.093023256,"the, a, virus, called"
46161,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.093023256,"sars-cov-2, humans, to, the"
46162,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.093023256,"the, also, to, is"
46163,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.093023256,"in, related, of, to"
46164,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.093023256,"are, the, in, and"
46165,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.093023256,"and, human, the, virus"
46166,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.093023256,"could, in, an, population"
46167,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.093023256,"a, and, sars-cov-2, or"
46168,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.093023256,"sars-cov-2, origin, is, and"
46169,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.093023256,"that, sars-cov-2, has, origin"
46170,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.093023256,"from, is, the, that"
46171,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.093023256,"of, sars-cov-2, is, and"
46172,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.093023256,"of, the, lineage, and"
46173,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.093023256,"with, other, and, virus"
46174,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.093023256,"of, and, closest, bat"
46175,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.093023256,"the, genome, covid-19, virus"
46176,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.093023256,"the, was, human, by"
46177,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.093023256,"from, of, the, virus"
46178,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.093023256,"the, of, from, with"
46179,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.093023256,"covid-19, be, the, from"
46180,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.093023256,"the, as, and, zoonotic"
46181,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.093023256,"the, in, as, and"
46182,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.093023256,"coronavirus, and, in, the"
46183,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.093023256,"viruses, to, and, the"
46184,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.093023256,"coronaviruses, are, in, of"
46185,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.093023256,"highly, sars-cov-2, of, coronaviruses"
46186,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.093023256,"the, bat, to, of"
46187,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.093023256,"that, a, sars-cov-2, by"
46188,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.093023256,"to, in, human, animal"
46189,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.093023256,"at, bat, that, the"
46190,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.093023256,"and, that, is, bat"
46191,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.093023256,"is, that, the, genomic"
46192,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.093023256,"that, the, bat, and"
46193,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.093023256,"the, of, and, novel"
46194,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.093023256,"a, the, market, from"
46195,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.093023256,"is, and, transmitted, the"
46196,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.093023256,"the, of, and, which"
46197,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.093023256,"the, of, is, animal"
46198,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.093023256,"isolated, at, market, that"
46199,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.093023256,"that, in, china, and"
46200,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.093023256,"that, a, first, in"
46201,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.093023256,"the, of, sequences, that"
46202,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.093023256,"that, of, the, genomic"
46203,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.093023256,"of, the, that, sequences"
46204,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.093023256,"in, bat, sars-cov, and"
46205,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.093023256,"may, from, bat, virus"
46206,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.093023256,"the, pangolin, intermediate, for"
46207,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.093023256,"sars-cov, and, sars-cov-2, a"
46208,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.093023256,"two, of, sars-cov-2, and"
46209,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.093023256,"the, and, of, a"
46210,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.093023256,"a, and, the, that"
46211,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.093023256,"sars-cov, and, to, the, of, that, in, a"
46212,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.093023256,"of, the, animal, hosts"
46213,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.093023256,"humans, other, of, and"
46214,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.093023256,"most, the, of, hosts"
46215,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.093023256,"that, the, part, of"
46216,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.093023256,"serve, as, the, of"
46217,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.093023256,"pangolin, to, the, intermediate"
46218,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.093023256,"sars-cov-2, south, china, from"
46219,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.093023256,"a, sars-cov-2, the, china"
46220,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.093023256,"the, from, a, with"
46221,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.093023256,"to, a, at, the"
46222,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.093023256,"the, to, in, a, of, with, was, that"
46223,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.093023256,"to, the, that, in"
46224,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.093023256,"genome, in, the, of"
46225,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.093023256,"the, of, that, may"
46226,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.093023256,"that, could, only, the"
46227,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.093023256,"the, suggesting, that, be"
46228,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.093023256,"in, is, the, covid-19"
46229,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.093023256,"is, on, to, the"
46230,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.093023256,"on, in, wuhan, the"
46231,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.093023256,"the, from, in, horseshoe"
46232,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.093023256,"of, the, ratg13,, sars-cov-2"
46233,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.093023256,"a, sars-cov-2, to, sample"
46234,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.093023256,"since, the, that, of"
46235,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.093023256,"of, be, origin, that"
46236,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.093023256,"that, the, for, on"
46237,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.093023256,"viruses, the, in, for"
46238,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.093023256,"laboratory, to, the, a"
46239,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.093023256,"human, by, the, was"
46240,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.093023256,"viruses, a, of, species"
46241,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.093023256,"a, are, the, of"
46242,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.093023256,"of, around, the, by"
46243,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.093023256,"are, also, related, to"
46244,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.093023256,"a, from, the, with"
46245,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.093023256,"it, the, of, from"
46246,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.093023256,"sars-cov-2, to, a, or"
46247,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.093023256,"in, it, the, sars-cov-2"
46248,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.093023256,"in, the, sars-cov-2, cov"
46249,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.093023256,"to, a, the, of"
46250,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.093023256,"of, covid-19, the, wuhan"
46251,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.093023256,"the, was, december, and"
46252,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.093023256,"the, was, december, 2019,, and, to, by, had"
46253,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.093023256,"that, to, the, into"
46254,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.093023256,"in, sars-cov-2, to, that"
46255,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.093023256,"the, of, is, in, found, a, to, that"
46256,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.093023256,"the, that, of, sars-cov-2, in, study, from, a"
46257,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.093023256,"the, sars-cov-2, of, from"
46258,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.093023256,"sars-cov-2, is, the, to"
46259,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.093023256,"from, virus, to, the"
46260,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.093023256,"the, of, by, is"
46261,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.093023256,"ratg13,, the, sars-cov-2, of"
46262,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.093023256,"of, shows, sequence, ratg13,"
46263,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.093023256,"the, to, ratg13, sars-cov-2"
46264,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.093023256,"of, the, sars-cov-2, in"
46265,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.093023256,"found, the, of, to"
46266,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.093023256,"sars-cov-2, has, to, and"
46267,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.093023256,"the, to, infection, from"
46268,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.093023256,"of, which, with, sars-cov-2"
46269,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.093023256,"sequence, with, the, sars-cov-2"
46270,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.093023256,"the, rbd, of, sars-cov-2"
46271,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.093023256,"the, sars-cov-2, be, in"
46272,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.093023256,"to, this, that, be"
46273,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.093023256,"in, ace2, to, the"
46274,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.093023256,"a, the, to, in"
46275,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.093023256,"the, in, to, can"
46276,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.093023256,"a, in, the, ("
46277,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.093023256,"viral, human, a, the"
46278,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.093023256,"that, in, infect, and"
46279,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.093023256,"to, a, common, sars-cov-2"
46280,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.093023256,"to, the, rbd, a"
46281,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.093023256,"the, to, a, as"
46282,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.093023256,"to, the, from, an"
46283,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.093023256,"supporting, a, the, and"
46284,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.093023256,"seafood, market, in, the"
46285,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.093023256,"the, in, sars-cov-2, at"
46286,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.093023256,"the, sequences, that, of"
46287,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.093023256,"that, the, in, samples"
46288,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.093023256,"the, genetic, of, in"
46289,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.093023256,"sars-cov-2, with, bat, in"
46290,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.093023256,"of, sars-cov-2, from, in"
46291,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.093023256,"sars-cov-2, that, from, the"
46292,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.093023256,"in, the, of, a, that, from, to, and"
46293,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.093023256,"sars-cov-2, is, a, virus"
46294,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.093023256,"a, sars-cov-2, zoonotic, spillover"
46295,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.093023256,"a, of, the, sars-cov-2"
46296,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.093023256,"the, and, or, of"
46297,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Bats are the second  

largest order of mammals, with over 1,230 species.",0.093023256,"of, the, bats, species."
46298,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.093023256,"the, of, serve, as"
46299,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.093023256,"and, the, bats, to"
46300,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.093023256,"the, of, to, most"
46301,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.093023256,"the, of, most, bat"
46302,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.093023256,"sars-cov-2, and, closely, related"
46303,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.093023256,"and, that, most, bat"
46304,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.093023256,"that, and, in, china"
46305,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.093023256,"and, that, the, most"
46306,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.093023256,"that, sars-cov-2, are, in"
46307,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.093023256,"the, bat, to, in"
46308,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.093023256,"to, in, and, were"
46309,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.093023256,"in, the, of, to"
46310,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.093023256,"the, of, are, bat"
46311,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.093023256,"by, in, the, are"
46312,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.093023256,"the, of, same, and"
46313,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.093023256,"infected, similar, to, and, can, with, the, of"
46314,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.093023256,"that, the, with, of, virus, and, less, to"
46315,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.093023256,"to, of, sars-cov-2, from"
46316,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.093023256,"from, of, to, sars-cov-2"
46317,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.093023256,"a, to, common, sars-cov-2"
46318,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.093023256,"have, a, of, known"
46319,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.093023256,"of, a, to, which"
46320,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.093023256,"of, sars-cov-2, a, with"
46321,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.093023256,"sars-cov-2,, the, which, to"
46322,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.093023256,"the, similar, to, is"
46323,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.093023256,"the, is, approximately, similar"
46324,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.093023256,"also, to, related, are"
46325,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.093023256,"the, sars-cov-2, to, also"
46326,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.093023256,"the, to, of, is"
46327,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.093023256,"that, of, to, is, a, found, in, the"
46328,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",all three BANAL series viruses also use ACE2 as an entry receptor.,0.093023256,"also, an, viruses, receptor."
46329,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.093023256,"the, have, of, than"
46330,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.093023256,"sars-cov-2., to, the, that"
46331,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","This suggests that the BANAL series may be able to directly infect  

humans.",0.093023256,"the, to, that, this"
46332,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","This suggests that the BANAL series may be able to directly infect  

humans.",0.093023256,"that, may, to, the"
46333,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.093023256,"a, the, to, at"
46334,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.093023256,"in, and, to, through"
46335,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.093023256,"of, virus, the, by"
46336,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.093023256,"the, of, is, by"
46337,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.093023256,"the, in, sars-cov-2, be"
46338,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.093023256,"the, virus, in, covid-19"
46339,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.093023256,"the, of, is, covid-19"
46340,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.093023256,"approximately, of, the, covid-19"
46341,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.093023256,"is, approximately, similar, the"
46342,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.093023256,"covid-19, is, the, in"
46343,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.093023256,"sars-cov-2, it, the, in"
46344,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.093023256,"the, and, by, a"
46345,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.093023256,"to, the, severe, in, of, suggesting, that, a"
46346,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.093023256,"the, guangdong, in, with, by, of, had, a, to, that, positive, virus"
46347,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.093023256,"a, virus, from, to, only, of, and, as"
46348,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.093023256,"to, an, for, the, of, evidence, infected, at, market, samples, taken, that"
46349,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.093023256,"to, from, a, of, in, the, and, that"
46350,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.093023256,"bats, of, and, are, to, the, reservoir, animal"
46351,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.093023256,"were, to, a, and, wet, animal, market, in"
46352,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.093023256,"a, in, the, with, that, was, to, of"
46353,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.093023256,"the, that, known, to, have, in, is, by, of, and, not, similarly,"
46354,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.093023256,"a, that, the, and, for, to, is, by"
46355,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.093023256,"a, that, zoonotic, spillover"
46356,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.093023256,"animal, and, are, the"
46357,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.093023256,"and, some, to, the"
46358,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.093023256,"study, that, of, from, a, in, sars-cov-2, the"
46359,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.093023256,"is, to, the, on"
46360,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","expended to make the simple point 

that COVID-19 had a natural origin.",0.093023256,"that, a, had, the"
46361,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","expended to make the simple point 

that COVID-19 had a natural origin.",0.093023256,"that, a, the, covid-19"
46362,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.093023256,"were, in, related, to"
46363,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.093023256,"sars-cov-2, that, in, and"
46364,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.093023256,"from, south, china, sars-cov-2"
46365,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.093023256,"that, bats, pangolins, sars-cov-2"
46366,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.093023256,"the, to, which, in"
46367,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.093023256,"the, in, a, to"
46368,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.093023256,"the, results, in, which"
46369,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.093023256,"to, in, the, which"
46370,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.093023256,"animal, in, zoonotic, origin"
46371,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.093023256,"sars-cov-2, has, humans, in"
46372,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.093023256,"an, and, or, in"
46373,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.093023256,"the, in, samples, that"
46374,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.093023256,"the, shows, that, a"
46375,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.093023256,"sars-cov-2, not, that, is"
46376,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.093023256,"this, that, sars-cov-2, or"
46377,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.093023256,"the, binding, to, sars-cov-2"
46378,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.093023256,"sars-cov-2, of, that, it"
46379,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.093023256,"a, of, coronavirus, that"
46380,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.093023256,"the, have, been, of"
46381,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.093023256,"of, the, had, been"
46382,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.093023256,"the, identical, to, human"
46383,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.093023256,"that, which, can, and"
46384,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.093023256,"a, that, shows, the"
46385,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.093023256,"the, genomic, that, of"
46386,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.093023256,"to, in, the, can"
46387,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.093023256,"a, and, nearly, identical"
46388,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.093023256,"sars-cov-2, a, and, or"
46389,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.093023256,"from, with, the, of"
46390,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.093023256,"however,, a, of, more"
46391,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.093023256,"of, these, with, sars-cov-2"
46392,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.093023256,"sars-cov-2, the, with, or"
46393,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.093023256,"the, and, not, but"
46394,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.",0.093023256,"with, the, of, a"
46395,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.093023256,"analysis, that, bat, the"
46396,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.093023256,"the, most, of, bat"
46397,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.093023256,"a, virus, the, called"
46398,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.093023256,"and, multiple, to, the, of, that, in, a"
46399,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.093023256,"the, of, genetic, in"
46400,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.093023256,"genetic, and, of, the"
46401,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.093023256,"the, and, cov, than"
46402,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.093023256,"analysis, that, to, the"
46403,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.093023256,"that, to, and, from"
46404,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.093023256,"the, of, animal, hosts"
46405,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.093023256,"of, these, a, which"
46406,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.093023256,"these, that, the, of"
46407,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.093023256,"the, that, of, sars-cov,"
46408,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.093023256,"the, that, of, re-"
46409,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.093023256,"the, of, humans, intermediate"
46410,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.093023256,"and, the, of, to, bats, that, in, virus"
46411,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.093023256,"to, in, through, and"
46412,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",Bats are hosts of many coronaviruses,0.093023256,"coronaviruses, bats, are, of"
46413,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.093023256,"in, is, the, to"
46414,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.093023256,"that, the, of, have"
46415,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.093023256,"a, of, in, that, the, suggesting, to, severe"
46416,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.093023256,"the, southern, of, china, have, in, markets, and"
46417,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.093023256,"the, animals, that, be"
46418,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.093023256,"in, which, results, the"
46419,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.093023256,"which, the, in, animals"
46420,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.093023256,"that, has, the, with"
46421,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.093023256,"known, of, have, a"
46422,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.093023256,"the, in, only, china"
46423,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.093023256,"is, bat, the, in"
46424,"Bats are the second  

largest order of mammals, with over 1,230 species.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.093023256,"bats, the, of, species."
46425,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.093023256,"bats, be, of, and"
46426,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.093023256,"the, bats, from, and"
46427,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.093023256,"to, the, from, and"
46428,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.093023256,"the, from, and, to"
46429,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.093023256,"the, humans, intermediate, host"
46430,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.093023256,"the, in, and, humans"
46431,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.093023256,"was, found, in, the"
46432,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.093023256,"of, and, virus, from, a, only, as, to"
46433,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.093023256,"to, bats, in, be"
46434,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.093023256,"are, or, bats, in"
46435,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.093023256,"the, and, which, have, to, a, of, in"
46436,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.093023256,"the, of, and, have, in, southern, china, markets"
46437,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.093023256,"and, of, the, a"
46438,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.093023256,"the, of, and, was"
46439,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.093023256,"sars-cov-2, origin, and, is"
46440,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.093023256,"sars-cov-2, the, origin, guangdong"
46441,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.093023256,"a, of, in, guangdong, that, positive, with, by, had, the, to, virus"
46442,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.093023256,"they, in, the, bats"
46443,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.093023256,"and, in, china,, bats"
46444,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.093023256,"and, in, an, or"
46445,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.093023256,"the, covid-19, and, that"
46446,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.093023256,"this, is, the, that"
46447,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.093023256,"to, the, from, for"
46448,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.093023256,"from, to, the, infection"
46449,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.093023256,"also, to, a, the"
46450,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.093023256,"the, in, very, and"
46451,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.093023256,"the, and, in, is"
46452,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.093023256,"and, in, the, is"
46453,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.093023256,"of, however,, a, more"
46454,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.093023256,"by, with, the, in"
46455,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.093023256,"are, by, in, the"
46456,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.093023256,"to, sars-cov-2, from, intermediate"
46457,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.093023256,"that, first, in, a"
46458,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.093023256,"it, that, a, sars-cov-2"
46459,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.093023256,"a, that, to, bat"
46460,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.093023256,"that, sars-cov-2, in, an"
46461,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.093023256,"sars-cov-2, to, through, is"
46462,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.093023256,"to, sars-cov-2, sample, a"
46463,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.093023256,"wildlife, that, or, is"
46464,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.093023256,"is, that, wildlife, or"
46465,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.093023256,"that, sars-cov-2, to, as"
46466,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.093023256,"to, that, in, humans"
46467,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.093023256,"that, he, the, a, of, has, been, origin."
46468,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.093023256,"the, have, and, reservoirs"
46469,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.093023256,"the, and, for, sars-cov"
46470,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.093023256,"the, of, sars-cov, and, that, a, in, to"
46471,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.093023256,"the, of, that, in, a, multiple, and, to"
46472,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.093023256,"the, and, a, in, to, that, not, of"
46473,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.093023256,"the, as, more, zoonotic"
46474,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.093023256,"to, sars-cov-2, the, bat"
46475,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.093023256,"that, human, origin, and"
46476,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.093023256,"the, virus, human, and"
46477,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.093023256,"the, that, most, and"
46478,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.093023256,"the, genetic, of, and"
46479,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.093023256,"as, the, of, are, for, they, genetic, laboratory"
46480,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.093023256,"to, that, from, and"
46481,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.093023256,"are, to, and, was"
46482,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.093023256,"of, with, sars-cov-2, these"
46483,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.093023256,"this, that, the, origin"
46484,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.093023256,"the, be, with, sars-cov-2"
46485,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.093023256,"sars-cov, and, sars-cov-2, bat"
46486,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.093023256,"these, the, was, of"
46487,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.093023256,"to, sars-cov-2, was, the"
46488,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.093023256,"the, in, animals, which"
46489,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.093023256,"that, is, evidence, to"
46490,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.093023256,"the, on, that, for"
46491,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.093023256,"that, sars-cov-2, bats, pangolins"
46492,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.093023256,"that, the, sars-cov-2, bats"
46493,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.093023256,"the, also, to, sars-cov-2"
46494,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.093023256,"also, a, the, and"
46495,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.093023256,"hosts, that, for, and"
46496,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.093023256,"virus, that, bats, the"
46497,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.093023256,"the, that, virus, for"
46498,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.093023256,"that, it, to, as, the, a, is, for"
46499,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.093023256,"sars-cov-2, genome, bat, the"
46500,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.093023256,"the, sars-cov-2, at, in"
46501,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.093023256,"a, the, china, sars-cov-2"
46502,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.093023256,"at, in, the, genome"
46503,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.093023256,"in, to, of, which"
46504,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.093023256,"of, sequence, shows, ratg13,"
46505,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.093023256,"these, a, which, of"
46506,all three BANAL series viruses also use ACE2 as an entry receptor.,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.093023256,"viruses, also, an, receptor."
46507,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.093023256,"of, in, related, to"
46508,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.093023256,"that, sars-cov-2, could, are"
46509,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.093023256,"for, that, be, hosts"
46510,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.093023256,"could, population, an, in"
46511,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.093023256,"that, are, sars-cov-2, in"
46512,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.093023256,"that, with, sars-cov-2, in"
46513,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.093023256,"recombination, the, for, and"
46514,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.093023256,"of, the, is, sars-cov-2"
46515,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.093023256,"of, sars-cov-2, is, the"
46516,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.093023256,"to, in, whole, genome"
46517,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.093023256,"evidence, that, or, in"
46518,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.093023256,"is, that, the, bats"
46519,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.093023256,"this, that, the, is"
46520,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.093023256,"and, the, from, bats"
46521,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.093023256,"of, the, viruses, from"
46522,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.093023256,"that, the, to, sars-cov-2."
46523,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same",0.093023256,"bat, cov, the, same"
46524,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.093023256,"is, with, the, in"
46525,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.093023256,"is, originated, in, to"
46526,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.093023256,"the, to, bat, very"
46527,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.093023256,"to, sars-cov-2, originated, the"
46528,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.093023256,"in, the, cov, originated"
46529,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.093023256,"the, of, pangolin, bat"
46530,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.093023256,"the, of, or, this"
46531,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.093023256,"in, the, that, bats"
46532,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.093023256,"cov, that, which, and"
46533,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.093023256,"the, than, and, cov"
46534,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.093023256,"the, that, with, sars-cov-2"
46535,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.093023256,"the, with, sars-cov-2, or"
46536,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.093023256,"the, that, has, with"
46537,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.093023256,"the, sars-cov-2, origin, guangdong"
46538,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.093023256,"the, that, sars-cov-2, or"
46539,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.093023256,"the, of, sars-cov-2, origin"
46540,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.093023256,"origin, the, that, this"
46541,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.093023256,"the, origin, are, sars-cov-2"
46542,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.093023256,"of, sars-cov-2, origin, that"
46543,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.093023256,"the, sars-cov-2, of, this"
46544,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.093023256,"the, or, of, and"
46545,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.093023256,"and, that, the, bat"
46546,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.093023256,"are, the, origin, sars-cov-2"
46547,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.093023256,"sars-cov-2, or, that, this"
46548,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.093023256,"that, may, have, sars-cov-2"
46549,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.093023256,"as, the, of, and, are, to, for, more"
46550,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.093023256,"in, the, genome, of"
46551,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.093023256,"the, in, wuhan, on"
46552,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.093023256,"the, to, a, also"
46553,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.093023256,"that, sars-cov-2, a, to"
46554,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.093023256,"sars-cov-2, with, a, that"
46555,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.093023256,"to, sars-cov-2, has, and"
46556,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.093023256,"is, identical, to, the"
46557,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.093023256,"sars-cov, and, sars-cov-2, with"
46558,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.093023256,"is, and, of, sars-cov-2"
46559,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.093023256,"with, the, of, and"
46560,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.093023256,"of, and, the, same"
46561,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.093023256,"the, and, of, with"
46562,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.093023256,"the, of, pangolin-cov, sars-cov-2"
46563,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.093023256,"the, and, from, spillover"
46564,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.093023256,"recombination, and, the, for"
46565,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.093023256,"the, that, in, evidence"
46566,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.093023256,"the, in, a, from"
46567,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.093023256,"the, from, and, in"
46568,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.093023256,"originated, in, the, cov"
46569,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.093023256,"sars-cov, and, are, a"
46570,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.093023256,"sars-cov-2, with, and, sars-cov"
46571,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.093023256,"with, and, similarity, sars-cov-2"
46572,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.093023256,"the, and, sars-cov-2, in"
46573,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.093023256,"the, binding, sars-cov-2, to"
46574,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.093023256,"the, that, and, pangolin"
46575,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.093023256,"the, that, in, it"
46576,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.093023256,"be, that, and, the"
46577,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.093023256,"the, of, rbd, sars-cov-2"
46578,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.093023256,"the, that, bats, sars-cov-2"
46579,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.093023256,"sars-cov-2, the, cov, in"
46580,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.093023256,"the, sars-cov-2, as, for"
46581,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.093023256,"sars-cov-2, origin, of, has, to, virus, that, the"
46582,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.093023256,"to, the, sars-cov-2, origin"
46583,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.093023256,"with, and, of, at"
46584,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.093023256,"the, of, zoonotic, from"
46585,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.093023256,"a, zoonotic, of, to"
46586,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.093023256,"of, the, from, a"
46587,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.093023256,"a, the, rbd, to"
46588,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.093023256,"of, virus, to, the"
46589,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.093023256,"that, observed, in, as"
46590,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.093023256,"the, that, animal, was"
46591,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.093023256,"to, studies, is, be"
46592,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.093023256,"the, be, sars-cov-2, present"
46593,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.093023256,"sars-cov-2, the, be, of"
46594,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.093023256,"the, virus, and, a"
46595,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.093023256,"the, sars-cov-2, and, an"
46596,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.093023256,"from, be, the, covid-19"
46597,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.093023256,"to, the, of, natural"
46598,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.093023256,"of, the, with, and"
46599,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.093023256,"the, supporting, a, and"
46600,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.093023256,"the, a, also, and"
46601,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.093023256,"to, that, origin, in"
46602,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.093023256,"genome, at, the, in"
46603,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.093023256,"in, that, the, sars-cov-2"
46604,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.093023256,"sars-cov-2, that, to, the"
46605,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.093023256,"the, coronavirus, bat, to"
46606,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.093023256,"the, to, bat, in"
46607,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.093023256,"a, the, of, and, in, that, not, but"
46608,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.093023256,"and, to, not, the, of, that, in, a"
46609,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.093023256,"of, including, and, viruses"
46610,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.093023256,"in, bats,, and, to"
46611,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.093023256,"it, that, of, bat"
46612,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.093023256,"of, sars-cov-2, highly, coronaviruses"
46613,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.093023256,"to, of, an, the"
46614,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.093023256,"is, related, to, the"
46615,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.093023256,"and, some, the, to"
46616,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.092783505,"to, the, have, in, of, and, that, a, covid-19"
46617,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.092783505,"in, the, that, virus, was, to, a, is, and"
46618,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.092783505,"and, the, to, are, a, with, that, in, for"
46619,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.092783505,"from, the, to, a, that, this, bat, of, at"
46620,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.092783505,"is, to, the, that, has, been, by, an, this"
46621,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.092783505,"the, of, a, in, and, animals, were, virus, at"
46622,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.092783505,"the, that, as, virus, was, to, a, coronavirus, and"
46623,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.092783505,"to, the, and, a, high, percentage, sequence, that, genome"
46624,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.092783505,"and, the, of, bat, as, a, with, for, is"
46625,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.092783505,"the, from, that, palm, civets, positive, for, at, market"
46626,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.092783505,"to, of, bats,, is, likely, that, by, animal, and"
46627,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.092783505,"the, of, in, species, to, bats, and, were, ace2"
46628,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.092783505,"the, was, able, to, a, that, and, infect, in"
46629,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.092783505,"in, the, a, that, are, to, and, with, for"
46630,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.092783505,"a, for, the, as, of, bat, is, and, with"
46631,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.092783505,"to, in, the, this, that, for, is, result, of"
46632,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.092783505,"a, of, the, also, are, that, other, to, virus"
46633,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.092783505,"of, to, sars-related, the, bat, most, closely, related, virus"
46634,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.092783505,"a, in, the, that, animal, but, human, or, during"
46635,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.092783505,"also, that, with, the, of, suggesting, have, to, an"
46636,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.092783505,"a, is, the, to, that, in, virus, and, was"
46637,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.092783505,"the, virus, was, as, a, coronavirus, that, and, to"
46638,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.092783505,"the, from, civets, at, market, positive, for, that, palm"
46639,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.092783505,"data, that, did, from, a, to, first, in, wildlife"
46640,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.092783505,"the, of, a, to, in, and, were, virus, palm"
46641,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.092783505,"the, genome, to, and, that, sequence, a, high, percentage"
46642,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.092783505,"have, that, bats, the, reservoir, for, a, of, and"
46643,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.092783505,"in, ace2, species, of, bats, were, to, and, the"
46644,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.092783505,"the, of, most, closely, related, virus, to, bat, sars-related"
46645,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.092783505,"a, at, to, bat, that, the, of, from, this"
46646,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.092783505,"a, that, the, was, able, to, infect, and, in"
46647,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.092783505,"of, a, that, the, virus, to, bat, and, sars"
46648,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.092783505,"the, bat, coronavirus, known, to, closest, its, in, of"
46649,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.092783505,"is, and, bats,, likely, that, of, to, animal, by"
46650,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.092783505,"the, of, to, that, this, in, for, result, is"
46651,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.092783505,"of, covid-19, to, a, have, that, in, and, the"
46652,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.092783505,"several, in, bats, which, are, to, of, on, and"
46653,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.092783505,"a, at, the, of, and, in, animals, virus, were"
46654,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.092783505,"the, of, and, were, virus, palm, a, in, to"
46655,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.092783505,"sars-cov, and, to, was, the, of, have, in, a"
46656,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.092783505,"the, of, also, to, are, a, other, that, virus"
46657,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.092783505,"in, first, from, that, did, to, data, wildlife, a"
46658,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.092783505,"the, of, have, a, to, in, and, sars-cov, was"
46659,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.092783505,"bats, which, on, several, of, are, to, and, in"
46660,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.092783505,"that, to, this, the, an, by, is, has, been"
46661,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.092783505,"the, to, a, virus, that, bat, and, sars, of"
46662,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.092783505,"and, the, of, to, are, as, bats, that, for"
46663,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.092783505,"the, bats, for, and, a, reservoir, of, that, have"
46664,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.092783505,"that, a, the, animal, human, or, in, during, but"
46665,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.092783505,"the, to, bat, in, of, coronavirus, closest, known, its"
46666,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.092783505,"that, the, an, with, of, suggesting, also, have, to"
46667,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.092715232,"in, of, to, sars-related, yunnan, the, positive, for, coronavirus, bat, and, had, were, related"
46668,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.092715232,"the, guangdong, live, in, with, all, of, had, a, to, that, at, least, virus"
46669,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.092715232,"with, the, and, for, of, a, or, to, however,, that, were, in, sars, by"
46670,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.092715232,"and, of, the, to, related, in, were, had, yunnan, bat, positive, for, sars-related, coronavirus"
46671,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.092715232,"by, the, of, a, in, to, that, sars, with, and, however,, or, were, for"
46672,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.092715232,"that, had, a, the, virus, with, of, in, at, least, guangdong, all, to, live"
46673,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.092592593,"of, coronaviruses, a, in, viruses"
46674,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.092592593,"of, and, from, bats, pangolins"
46675,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.092592593,"a, that, the, of, from"
46676,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.092592593,"data, and, that, bats, of"
46677,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.092592593,"the, of, in, from, that"
46678,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.092592593,"the, in, pangolins, of, that"
46679,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.092592593,"sars-cov-2, contains, genetic, to, coronaviruses"
46680,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.092592593,"a, and, to, which, in"
46681,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.092592593,"and, very, to, human, in"
46682,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.092592593,"a, which, bat, in, pangolin"
46683,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.092592593,"are, viruses, to, in, and"
46684,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.092592593,"the, and, to, be, of"
46685,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.092592593,"the, species, of, to, and"
46686,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.092592593,"that, virus, bats, and, of"
46687,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.092592593,"to, sequences, in, and, coronaviruses"
46688,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.092592593,"emerged, of, sars-cov-2, and, sars-cov"
46689,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.092592593,"of, sars-cov-2, and, sars-cov, which"
46690,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.092592593,"and, the, masked, palm, civet"
46691,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.092592593,"to, the, of, sars-cov-2, as"
46692,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.092592593,"of, in, the, with, widely"
46693,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.092592593,"that, of, have, origin, sars-cov-2"
46694,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.092592593,"sars-cov-2, to, coronaviruses, genetic, contains"
46695,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.092592593,"that, have, from, the, of"
46696,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.092592593,"to, sars-cov-2, that, from, the"
46697,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.092592593,"the, of, that, sars-cov-2, been"
46698,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.092592593,"the, it, would, to, of"
46699,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.092592593,"a, sars-cov-2, genetic, the, in"
46700,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.092592593,"genetic, of, the, probably, have"
46701,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.092592593,"also, that, the, sars-cov-2, is"
46702,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.092592593,"that, sars-cov-2, also, a, the"
46703,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.092592593,"is, the, its, sequence, in"
46704,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.092592593,"sars-cov-2, a, and, that, with"
46705,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.092592593,"that, and, sars-cov-2, other, with"
46706,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.092592593,"the, of, that, to, coronaviruses"
46707,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.092592593,"of, the, bat, viruses, that"
46708,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.092592593,"and, to, 19, of, the"
46709,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.092592593,"the, highly, that, to, with"
46710,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.092592593,"that, sars-cov-2, with, identified, to"
46711,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.092592593,"the, that, sars-cov-2, have, to"
46712,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.092592593,"the, as, natural, bat, with"
46713,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.092592593,"to, sars-cov-2, the, that, natural"
46714,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.092592593,"sars-cov-2, to, a, found, bat"
46715,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.092592593,"the, is, a, sequence, that"
46716,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.092592593,"are, natural, of, and, a"
46717,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.092592593,"overall, to, the, that, human"
46718,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.092592593,"that, of, were, in, and"
46719,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.092592593,"in, of, that, pangolin, which"
46720,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.092592593,"the, to, have, that, of"
46721,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.092592593,"that, the, of, have, to"
46722,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.092592593,"the, that, of, human, in"
46723,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.092592593,"of, the, in, a, that"
46724,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.092592593,"of, and, viruses, are, the"
46725,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.092592593,"to, a, similarity, and, in"
46726,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.092592593,"that, the, in, a, to"
46727,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.092592593,"as, of, the, to, sars-cov-2"
46728,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.092592593,"the, of, for, to, sars-cov-2"
46729,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.092592593,"of, sars-cov-2, the, for, to"
46730,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.092592593,"in, the, has, and, as"
46731,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.092592593,"the, in, zoonotic, to, of"
46732,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.092592593,"the, in, that, of, is"
46733,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.092592593,"are, the, and, that, bats"
46734,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.092592593,"bats, the, of, and, be"
46735,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.092592593,"to, sars-cov, that, hosts, for"
46736,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.092592593,"the, at, sars-cov, with, of"
46737,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.092592593,"the, of, sars-cov-2, sars-cov, at"
46738,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.092592593,"the, to, which, of, and"
46739,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.092592593,"the, of, bat, that, in"
46740,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.092592593,"the, in, that, bat, of"
46741,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.092592593,"that, to, with, highly, the"
46742,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.092592593,"a, at, the, was, from"
46743,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.092592593,"coronaviruses, a, that, to, and"
46744,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.092592593,"a, from, the, coronavirus, with"
46745,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.092592593,"at, was, in, the, with"
46746,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.092592593,"bats, are, of, and, to"
46747,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.092592593,"sars-cov-2, the, in, of, is"
46748,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.092592593,"that, other, not, it, was"
46749,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.092592593,"a, the, ruled, out, it"
46750,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.092592593,"identified, that, sars-cov-2, to, with"
46751,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.092592593,"found, sars-cov-2, to, a, bat"
46752,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.092592593,"a, to, in, similarity, and"
46753,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.092592593,"are, a, china, found, coronaviruses"
46754,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.092592593,"as, to, a, high, bat"
46755,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.092592593,"to, have, from, a, sars-cov-2"
46756,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.092592593,"that, sars-cov-2, to, humans, the"
46757,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.092592593,"the, genome, that, such, and"
46758,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.092592593,"the, that, are, and, genomic"
46759,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.092592593,"the, of, that, have, from"
46760,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.092592593,"the, of, for, probable, sars-cov-2"
46761,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.092592593,"that, a, the, we, to"
46762,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.092592593,"in, the, are, to, that"
46763,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.092592593,"the, a, was, from, at"
46764,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.092592593,"from, lineage, the, of, a"
46765,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.092592593,"et, al., the, of, confirmed"
46766,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.092592593,"that, the, and, sars-cov-2, than"
46767,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.092592593,"in, chinese, the, a, sars-cov-2"
46768,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.092592593,"in, the, that, a, sars-cov-2"
46769,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.092592593,"sars-cov-2, in, the, all, that"
46770,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.092592593,"was, that, the, were, of"
46771,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.092592593,"to, more, than, the, and"
46772,"All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.092592593,"the, in, a, chinese, sars-cov-2"
46773,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.092592593,"of, lineage, a, the, from"
46774,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.092592593,"the, from, to, a, in"
46775,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.092592593,"in, a, of, one, to, the, samples, from, different, two"
46776,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.092592593,"that, the, of, a, demic"
46777,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.092592593,"not, that, was, it, other"
46778,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.092592593,"confirmed, that, the, sars-cov-2, by"
46779,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.092592593,"the, that, as, evidence, to"
46780,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.092592593,"a, we, that, the, to"
46781,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.092592593,"of, yet, that, doesn’t, the"
46782,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.092592593,"that, the, for, very, to"
46783,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.092592593,"the, coronavirus, has, a, that"
46784,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.092592593,"a, that, coronaviruses, to, and"
46785,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.092592593,"coronaviruses, to, all, that, of"
46786,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.092592593,"a, of, that, have, to"
46787,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.092592593,"to, that, of, and, have"
46788,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.092592593,"that, human, and, in, all"
46789,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.092592593,"and, to, from, animals, through"
46790,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.092592593,"of, to, intermediate, host, the"
46791,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.092592593,"be, possible, to, of, as"
46792,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.092592593,"and, that, of, were, in"
46793,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.092592593,"close, and, that, of, to"
46794,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.092592593,"of, and, a, in, the"
46795,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.092592593,"to, a, in, and, were"
46796,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.092592593,"the, of, that, which, to"
46797,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.092592593,"of, the, in, widely, with"
46798,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.092592593,"of, the, confirmed, et, al."
46799,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.092592593,"the, of, that, to, from"
46800,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.092592593,"is, an, which, the, from"
46801,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.092592593,"sars-cov-2, the, that, to, from"
46802,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.092592593,"a, be, the, that, bats"
46803,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.092592593,"is, a, the, from, pangolin"
46804,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.092592593,"and, of, the, to, pangolin, with, that, bat, for, coronavirus"
46805,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.092592593,"that, and, sars-cov-2, to, the"
46806,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.092592593,"has, the, and, to, that"
46807,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.092592593,"of, to, the, which, that"
46808,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.092592593,"from, in, the, a, to"
46809,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.092592593,"a, the, are, to, virus"
46810,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.092592593,"to, the, bats, and, are"
46811,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.092592593,"to, that, the, of, may"
46812,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.092592593,"the, of, and, has, bats"
46813,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.092592593,"as, the, of, that, is"
46814,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.092592593,"in, the, that, were, likely"
46815,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.092592593,"to, in, the, that, natural"
46816,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.092592593,"to, in, the, and, that"
46817,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.092592593,"was, the, in, seafood, of"
46818,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.092592593,"and, of, about, in, the"
46819,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.092592593,"bats, to, that, of, and"
46820,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.092592593,"the, is, natural, or, to"
46821,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.092592593,"the, and, is, natural, to"
46822,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.092592593,"is, to, the, host, or"
46823,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.092592593,"with, bat, as, the, natural"
46824,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.092592593,"a, the, it, ruled, out"
46825,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.092592593,"the, natural, reservoir, for, of"
46826,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.092592593,"that, the, is, bat, possible"
46827,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.092592593,"of, the, were, that, was"
46828,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.092592593,"seafood, in, the, was, of"
46829,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.092592593,"a, that, the, was, in"
46830,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.092592593,"it, that, a, of, the"
46831,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.092592593,"the, viruses, of, bat, that"
46832,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.092592593,"be, a, that, bats, the"
46833,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.092592593,"the, genome, of, bat, to"
46834,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.092592593,"the, has, to, bat, of"
46835,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.092592593,"the, that, sars-cov-2, confirmed, by"
46836,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.092592593,"that, sars-cov-2, the, which, for"
46837,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.092592593,"the, was, to, it, that"
46838,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.092592593,"also, that, the, to, host"
46839,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.092592593,"sars-cov-2., is, bat, to, the"
46840,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.092592593,"genome, the, bat, of, previously"
46841,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.092592593,"at, the, of, with, sars-cov"
46842,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.092592593,"the, key, rbd, as, with"
46843,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.092592593,"the, of, and, to, rbd"
46844,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.092592593,"or, bats, to, transmission, be"
46845,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.092592593,"bats, the, for, as, to"
46846,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.092592593,"sars-cov, and, sars-cov-2, emerged, of"
46847,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.092592593,"the, as, sars-cov-2, homology, with"
46848,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.092592593,"that, the, sars-cov-2, as, bat"
46849,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.092592593,"the, of, identical, and, sars-cov-2"
46850,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.092592593,"in, the, a, are, from"
46851,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.092592593,"from, in, the, of, a"
46852,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.092592593,"of, and, data, that, bats"
46853,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.092592593,"and, bats, is, most, by"
46854,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.092592593,"and, of, receptor, binding, is"
46855,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.092592593,"a, the, to, from, animals"
46856,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.092592593,"the, sars-cov-2, to, bat, coronaviruses"
46857,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.092592593,"the, from, to, humans, bat"
46858,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.092592593,"the, of, coronaviruses, in, to"
46859,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.092592593,"the, of, in, sars, to"
46860,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.092592593,"of, also, the, to, from"
46861,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.092592593,"the, human, market, and, in"
46862,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.092592593,"sars-cov-2, is, a, and, that"
46863,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.092592593,"and, that, sars-cov-2, is, natural"
46864,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.092592593,"that, of, close, to, and"
46865,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.092592593,"of, is, to, sars-cov-2, that"
46866,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.092592593,"and, the, of, to, that"
46867,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.092592593,"the, of, in, with, and"
46868,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.092592593,"this, of, the, in, virus"
46869,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.092592593,"the, isolated, in, from, of"
46870,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.092592593,"between, and, the, from, in"
46871,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.092592593,"to, the, bats, of, covid-19"
46872,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.092592593,"that, are, the, and, viruses"
46873,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.092592593,"of, human, in, associated, with"
46874,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.092592593,"the, has, of, bat, and"
46875,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.092592593,"that, and, such, the, genome"
46876,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.092592593,"that, the, wuhan, of, to"
46877,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.092592593,"the, that, of, covid-19, and"
46878,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.092592593,"of, animal, and, the, hosts"
46879,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.092592593,"was, in, a, and, at"
46880,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.092592593,"in, china, and, 2019, were"
46881,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.092592593,"of, amino, the, to, that"
46882,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.092592593,"a, is, virus, in, that"
46883,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.092592593,"the, were, likely, that, in"
46884,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.092592593,"in, a, of, the, from, for, identified, coronavirus, most, were"
46885,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.092592593,"a, of, from, in, identified"
46886,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.092592593,"that, and, sars-cov-2, the, with"
46887,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.092592593,"coronaviruses, of, a, viruses, in"
46888,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.092592593,"the, genome, of, to, bat"
46889,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.092592593,"the, of, in, to, coronaviruses"
46890,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.092592593,"the, of, a, and, ratg13"
46891,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.092592593,"bats, are, the, of, pangolins"
46892,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.092592593,"that, the, sars-cov-2, for, which"
46893,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.092592593,"the, of, which, that, sars-cov-2"
46894,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.092592593,"et, high, to, sars-cov-2, in"
46895,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.092592593,"can, be, that, coronavirus, to"
46896,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.092592593,"indicates, a, that, is, and"
46897,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.092592593,"sars-cov, and, sars-cov-2, of, which"
46898,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.092592593,"sars-cov-2, at, the, of, sars-cov"
46899,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.092592593,"that, a, similarity, of, sars-cov-2"
46900,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.092592593,"that, the, sars-cov-2, as, a"
46901,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.092592593,"the, which, to, that, of"
46902,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.092592593,"the, hypothesis, that, to, of"
46903,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.092592593,"the, of, evidence, this, that"
46904,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.092592593,"the, a, coronavirus, from, with"
46905,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.092592593,"a, of, the, after, that"
46906,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.092592593,"the, to, a, of, in"
46907,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.092592593,"the, a, of, that, to"
46908,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.092592593,"the, have, to, is, in"
46909,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.092592593,"the, sars-cov-2, and, to, of"
46910,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.092592593,"in, a, of, sars-cov-2, to"
46911,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.092592593,"the, of, on, a, that"
46912,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.092592593,"of, that, the, a, for"
46913,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.092592593,"of, natural, the, viruses, in"
46914,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.092592593,"the, of, and, a, ratg13"
46915,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.092592593,"a, from, of, and, as"
46916,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.092592593,"a, of, and, the, from"
46917,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.092592593,"this, ratg13, the, sars-cov-2, that"
46918,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.092592593,"in, the, that, sars-cov-2, but"
46919,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.092592593,"of, these, to, a, which"
46920,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.092592593,"a, are, coronaviruses, found, china"
46921,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.092592593,"a, of, zoonotic, and, the"
46922,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.092592593,"hosts, that, to, for, sars-cov"
46923,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.092592593,"the, sars-cov-2, a, genetic, in"
46924,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.092592593,"the, for, of, to, with, that, coronavirus, pangolin, and, bat"
46925,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.092592593,"to, a, as, high, bat"
46926,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.092592593,"the, of, that, wuhan, to"
46927,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.092592593,"the, is, that, of, covid-19"
46928,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.092592593,"the, genome, was, to, and"
46929,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.092592593,"has, the, of, with, sars-cov-2"
46930,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.092592593,"that, for, sars-cov-2, in, with"
46931,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.092592593,"the, intermediate, host, to, of"
46932,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.092592593,"species, to, sars-cov-2, in, the"
46933,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.092592593,"that, similarity, of, sars-cov-2, a"
46934,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.092592593,"sars-cov-2, high, et, to, in"
46935,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.092592593,"the, of, to, et, sars-cov-2"
46936,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.092592593,"has, the, in, as, and"
46937,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.092592593,"the, of, sars-cov-2, has, with"
46938,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).",0.092592593,"natural, of, the, cleavage, site, in, a, furin, to, that, such, insertion, can, naturally, animal"
46939,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.092592593,"can, be, to, that, coronavirus"
46940,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.092592593,"and, is, most, by, bats"
46941,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.092592593,"in, the, from, found, at, similar, to, by, is, and"
46942,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.092592593,"the, in, rbd, similar, to"
46943,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.092592593,"found, similar, to, and, the"
46944,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.092592593,"as, the, key, with, rbd"
46945,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.092592593,"homology, with, the, as, sars-cov-2"
46946,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.092592593,"that, sars-cov-2, natural, and, is"
46947,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.092592593,"animal, hosts, and, the, of"
46948,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.092592593,"the, also, that, hosts, for"
46949,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.092592593,"sars-cov-2, with, other, and, that"
46950,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.092592593,"to, the, that, sars-cov-2, humans"
46951,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.092592593,"to, that, sars-cov-2, the, and"
46952,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.092592593,"the, sars-cov-2, with, that, and"
46953,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.092592593,"rbd, sars-cov-2, to, the, in"
46954,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.092592593,"the, that, hosts, for, than"
46955,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.092592593,"that, the, hosts, for, and"
46956,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.092592593,"to, has, that, the, and"
46957,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.092592593,"to, bind, the, in, these"
46958,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.092592593,"have, that, are, the, and"
46959,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.092592593,"in, it, that, the, and"
46960,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.092592593,"to, sars-cov-2, the, rbd, ace2"
46961,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.092592593,"is, to, the, it, may"
46962,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.092592593,"and, to, the, evidence, of"
46963,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.092592593,"to, the, that, additional, and"
46964,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.092592593,"in, of, were, to, with"
46965,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.092592593,"to, in, sars-cov-2, species, the"
46966,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.092592593,"several, and, the, to, species"
46967,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.092592593,"at, in, the, to, were"
46968,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.092592593,"in, the, of, that, this"
46969,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.092592593,"that, the, of, at, from"
46970,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.092592593,"that, for, sars-cov-2, the, in"
46971,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.092592593,"evidence, that, bats, and, sars-cov-2"
46972,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.092592593,"for, the, natural, reservoir, of"
46973,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.092592593,"the, are, of, natural, for"
46974,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.092592593,"the, of, bats, for, are"
46975,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.092592593,"the, of, from, that, at"
46976,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.092592593,"the, of, a, or, that, covid-19, is, sars-cov-2, at, majority"
46977,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.092592593,"to, the, natural, is, or"
46978,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.092592593,"to, of, the, bats, and"
46979,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.092592593,"viruses, and, a, the, same"
46980,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.092592593,"the, of, a, viruses, in, multiple, species, to, that, as"
46981,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.092592593,"a, that, the, in, bat"
46982,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.092592593,"the, genetic, of, to, in"
46983,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.092592593,"that, a, bat, to, in"
46984,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.092592593,"sars-cov-2, have, from, to, a"
46985,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.092592593,"by, to, the, sars-cov-2, is"
46986,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.092592593,"was, and, in, at, a"
46987,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.092592593,"and, the, which, by, a"
46988,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.092592593,"the, to, rbd, of, and"
46989,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.092592593,"the, have, to, of, human"
46990,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.092592593,"to, the, of, human, with"
46991,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.092592593,"viruses, to, respiratory, in, that"
46992,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.092592593,"from, in, the, is, of"
46993,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.092592593,"viruses, the, have, of, a"
46994,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.092592593,"and, viruses, a, the, same"
46995,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.092592593,"to, and, is, viruses, related"
46996,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.092592593,"were, in, to, a, and"
46997,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.092592593,"to, the, of, bat, virus"
46998,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.092592593,"the, virus, of, to, bat"
46999,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.092592593,"the, of, to, is, most"
47000,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.092592593,"of, the, is, bat, as"
47001,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.092592593,"by, of, virus, to, the"
47002,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.092592593,"to, is, in, sars-cov-2, the"
47003,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.092592593,"more, than, the, to, and"
47004,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.092592593,"a, the, to, bat, and"
47005,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.092592593,"the, sars-cov-2, and, bat, than"
47006,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.092592593,"the, bat, to, in, than"
47007,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.092592593,"and, it, is, that, in"
47008,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.092592593,"a, with, on, to, the"
47009,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.092592593,"at, the, and, in, found, from, is, similar, to, by"
47010,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.092592593,"in, and, by, three, different, chinese, were, found, positive, for"
47011,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.092592593,"to, the, genome, in, and, that, bats, or, be, for"
47012,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.092592593,"that, the, of, multiple, species, in, as, viruses, a, to"
47013,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.092592593,"samples, from, in, two, different, one, the, of, a, to"
47014,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.092592593,"identified, in, the, of, a, coronavirus, from, were, most, for"
47015,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.092592593,"it, that, the, likely, reservoir, as, similar, to, a, bat"
47016,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.092592593,"a, virus, from, bat, to, of, and, some, as, markets"
47017,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.092592593,"similarly,, the, and, also, a, in, to, suggesting, bat, of"
47018,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.092592593,"bats, are, of, and, a, large, to, that, in, as"
47019,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.092592593,"the, of, a, to, animal, in, and, market, at, was"
47020,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.092592593,"is, that, sars-cov-2, a, the, covid-19, of, or, at, majority"
47021,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.092592593,"and, a, of, between, sars-cov-2, in, is, the, for, to"
47022,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.092592593,"and, to, in, a, which"
47023,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.092592593,"the, and, 19, of, to"
47024,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.092592593,"to, the, and, natural, is"
47025,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.092592593,"in, the, of, that, human"
47026,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.092592593,"genomic, that, and, are, the"
47027,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.092592593,"all, that, human, in, and"
47028,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.092592593,"the, human, in, market, and"
47029,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.092592593,"the, a, to, on, with"
47030,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.092592593,"that, to, and, pangolins, sars-cov-2"
47031,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.092592593,"a, the, of, and, to"
47032,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.092592593,"that, the, bat, in, a"
47033,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.092592593,"the, a, sequence, that, in"
47034,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.092592593,"the, on, that, a, of"
47035,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.092592593,"the, have, of, genetic, probably"
47036,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.092592593,",, of, the, to, that"
47037,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.092592593,"the, to, overall, that, human"
47038,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.092592593,"the, to, may, it, is"
47039,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.092592593,"all, coronaviruses, that, of, to"
47040,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.092592593,"the, natural, to, that, in"
47041,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.092592593,"the, key, of, is, to"
47042,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.092592593,"the, of, that, and, a"
47043,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.092592593,"by, a, and, which, the"
47044,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.092592593,"and, a, of, which, the"
47045,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.092592593,"it, that, the, a, of"
47046,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.092592593,"of, that, the, in, pangolins"
47047,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.092592593,"that, sars-cov-2, the, of, virus"
47048,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.092592593,"the, sars-cov-2, and, of, identical"
47049,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.092592593,"from, and, sars-cov-2, with, more"
47050,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.092592593,"the, that, all, sars-cov-2, and"
47051,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.092592593,"human, and, to, in, very"
47052,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.092592593,"to, the, that, and, but"
47053,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.092592593,"the, of, that, a, demic"
47054,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.092592593,"the, of, sars, in, to"
47055,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.092592593,"and, collaborative, to, the, of"
47056,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.092592593,"the, of, in, to, genetic"
47057,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.092592593,"that, is, bat, the, possible"
47058,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.092592593,"the, that, for, a, of"
47059,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.092592593,"the, of, as, is, bat"
47060,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.092592593,"a, bat, origin, of, the"
47061,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.092592593,"and, can, are, to, be"
47062,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.092592593,"bats, to, the, of, covid-19"
47063,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.092592593,"to, that, viruses, in, respiratory"
47064,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.092592593,"are, viruses, the, that, and"
47065,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.092592593,"the, all, rhinolophus, in, china"
47066,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.092592593,"the, results, in, that, be"
47067,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.092592593,"it, was, that, the, to"
47068,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.092592593,"rhinolophus, the, all, in, china"
47069,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.092592593,"in, of, bats, and, the"
47070,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.092592593,"of, the, in, and, viruses"
47071,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.092592593,"the, between, and, bat, viruses"
47072,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.092592593,"and, contact, to, bats, be"
47073,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.092592593,"the, and, masked, palm, civet"
47074,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.092592593,"in, the, bats, and, was"
47075,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.092592593,"possible, to, be, of, as"
47076,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.092592593,"of, as, a, from, and"
47077,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.092592593,"some, bat, to, a, as, from, virus, markets, of, and"
47078,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.092592593,"bats, to, be, or, transmission"
47079,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.092592593,"bats, to, contact, and, be"
47080,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.092592593,"and, to, at, the, market, in, of, a, was, animal"
47081,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.092592593,"is, sars-cov-2, guangdong, the, in"
47082,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.092592593,"and, in, were, china, 2019"
47083,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.092592593,"in, found, three, positive, for, chinese, different, were, by, and"
47084,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.092592593,"the, from, in, between, and"
47085,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.092592593,"the, from, an, between, and"
47086,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.092592593,"is, a, and, indicates, that"
47087,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.092592593,"and, the, of, that, is"
47088,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.092592593,"a, from, animals, to, the"
47089,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.092592593,"the, of, also, to, from"
47090,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.092592593,"several, species, to, and, the"
47091,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.092592593,"from, humans, to, bat, the"
47092,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.092592593,"r., to, that, of, the"
47093,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.092592593,"the, of, collaborative, and, to"
47094,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.092592593,"of, zoonotic, and, the, to"
47095,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.092592593,"have, a, that, of, to"
47096,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.092592593,"are, the, virus, to, a"
47097,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.092592593,"that, bat, in, a, to"
47098,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.092592593,"suggest, that, may, to, sars-cov-2"
47099,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.092592593,"yet, the, of, doesn’t, that"
47100,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.092592593,"he, that, the, of, sars-cov-2"
47101,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.092592593,"are, the, natural, for, of"
47102,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.092592593,"the, hypothesis, of, natural, as"
47103,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.092592593,"that, or, the, for, sars-cov-2"
47104,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.092592593,"a, of, the, has, origin"
47105,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.092592593,"the, of, natural, as, hypothesis"
47106,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.092592593,"the, of, and, as, origin"
47107,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.092592593,"the, of, evidence, and, to"
47108,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.092592593,"bat, pangolin, in, a, which"
47109,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.092592593,"the, an, which, is, from"
47110,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.092592593,"is, a, from, the, pangolin"
47111,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.092592593,"that, and, bats, of, to"
47112,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.092592593,"that, the, and, to, additional"
47113,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.092592593,"the, to, and, that, but"
47114,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.092592593,"between, an, and, the, from"
47115,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.092592593,"sars-cov-2, to, the, in, rbd"
47116,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.092592593,"in, the, to, bind, these"
47117,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.092592593,"that, the, sequence, is, a"
47118,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.092592593,"the, a, coronavirus, that, has"
47119,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.092592593,"a, sequence, that, the, in"
47120,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.092592593,"the, that, sars-cov-2, or, for"
47121,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.092592593,"from, that, to, and, the"
47122,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.092592593,"all, sars-cov-2, the, and, that"
47123,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.092592593,"evidence, sars-cov-2, bats, and, that"
47124,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.092592593,"also, that, the, hosts, for"
47125,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.092592593,"that, hosts, for, than, the"
47126,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.092592593,"to, were, in, at, the"
47127,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.092592593,"to, for, the, that, very"
47128,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.092592593,"bats, as, the, to, for"
47129,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.092592593,"bat, that, the, as, sars-cov-2"
47130,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.092592593,"the, a, to, bat, as, similar, that, likely, it, reservoir"
47131,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.092592593,"that, a, the, of, virus"
47132,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.092592593,"a, and, which, to, the"
47133,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.092592593,"the, of, sars-cov-2, at, in"
47134,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.092592593,"the, a, genome, of, bat"
47135,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.092592593,"of, the, bat, origin, a"
47136,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.092592593,"of, to, a, which, these"
47137,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.092592593,"in, a, of, found, to"
47138,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.092592593,"in, the, and, about, of"
47139,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.092592593,"receptor, binding, and, is, of"
47140,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.092592593,"the, and, for, of, a, to, in, is, between, sars-cov-2"
47141,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.092592593,"is, a, of, sars-cov-2, the"
47142,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.092592593,"in, for, that, sars-cov-2, with"
47143,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.092592593,"that, to, sars-cov-2, and, pangolins"
47144,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.092592593,"and, are, to, in, viruses"
47145,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.092592593,"that, bats, and, are, the"
47146,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.092592593,"to, the, bats, for, be, and, in, that, genome, or"
47147,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.092592593,"the, results, that, be, in"
47148,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.092592593,"the, evidence, that, in, for"
47149,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.092592593,"the, sars-cov-2, is, that, bat"
47150,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.092592593,"this, the, that, sars-cov-2, ratg13"
47151,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.092592593,"of, the, has, bats, and"
47152,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.092592593,"the, is, to, bat, sars-cov-2."
47153,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.092592593,"in, guangdong, is, sars-cov-2, the"
47154,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.092592593,"to, the, is, or, host"
47155,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.092592593,"sars-cov-2, of, bats, the, that"
47156,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.092592593,"the, of, that, this, than"
47157,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.092592593,"the, sequences, of, sars-cov-2, and"
47158,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.092592593,"is, also, that, sars-cov-2, the"
47159,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.092592593,"sars-cov-2, than, the, bat, and"
47160,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.092592593,"and, the, viruses, between, bat"
47161,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.092592593,"that, origin, of, sars-cov-2, have"
47162,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.092592593,"the, probable, for, of, sars-cov-2"
47163,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.092592593,"bats, are, the, for, of"
47164,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.092592593,"the, of, origin, as, and"
47165,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.092592593,"the, genome, of, bat, previously"
47166,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.092592593,"and, virus, the, in, of"
47167,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.092592593,"also, that, sars-cov-2, a, the"
47168,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.092592593,"the, and, found, similar, to"
47169,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.092592593,"the, of, sars-cov, and, to"
47170,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.092592593,"that, of, in, sars-cov-2, the"
47171,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.092592593,"the, of, that, in, and"
47172,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.092592593,"that, a, the, of, and"
47173,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.092592593,"that, and, hosts, for, the"
47174,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.092592593,"the, and, are, that, have"
47175,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.092592593,"from, with, and, more, sars-cov-2"
47176,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.092592593,"cov, with, sars-cov-2, more, than"
47177,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.092592593,"are, the, and, in, to"
47178,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.092592593,"of, at, the, to, that"
47179,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.092592593,"that, the, of, and, an"
47180,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.092592593,"in, of, and, that, the"
47181,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.092592593,"it, in, the, and, that"
47182,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.092592593,"of, the, to, sars-cov-2,, that"
47183,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.092592593,"that, of, in, which, pangolin"
47184,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.092592593,"to, of, is, that, in"
47185,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.092592593,"and, the, of, be, sars-cov-2"
47186,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.092592593,"the, of, that, evidence, this"
47187,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.092592593,"the, in, evidence, that, for"
47188,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.092592593,"a, that, the, sars-cov-2, for"
47189,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.092592593,"the, of, to, it, would"
47190,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.092592593,"identified, in, of, a, from"
47191,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.092592593,"coronaviruses, sars-cov-2, in, including, of"
47192,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.092592593,"to, sars-cov-2, in, of, a"
47193,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.092592593,"of, in, to, were, with"
47194,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.092592593,"of, to, a, found, in"
47195,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.092592593,"are, natural, of, a, and"
47196,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.092592593,"of, are, bats, and, to"
47197,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.092592593,"are, to, in, a, of, as, large, that, bats, and"
47198,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.092592593,"in, the, was, at, with"
47199,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.092592593,"the, sars-cov-2, to, of, in"
47200,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.092592593,"the, of, that, to, r."
47201,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.092592593,"the, amino, to, that, of"
47202,"The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.092592593,"the, of, furin, cleavage, in, natural, a, animal, to, that, site, can, such, naturally, insertion"
47203,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.092592593,"the, of, to, ,, that"
47204,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.092592593,"the, that, at, of, to"
47205,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.092592593,"the, of, to, sars-cov-2,, that"
47206,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.092592593,"to, in, than, the, bat"
47207,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.092592593,"the, of, has, to, bat"
47208,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.092592593,"bat, to, a, in, the, similarly,, suggesting, of, and, also"
47209,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.092592593,"that, of, in, to, and"
47210,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.092592593,"viruses, related, to, and, is"
47211,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.092592593,"in, it, is, that, and"
47212,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.092592593,"in, of, is, to, that"
47213,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.092592593,"that, the, also, to, host"
47214,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.092592593,"sars-, cov-2, the, of, to"
47215,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.092592593,"to, the, key, is, of"
47216,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.092436975,"a, of, the, market, and, were, in, to, with, that, majority"
47217,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.092436975,"the, malayan, from, in, with, of, dead, a, to, that, sars-cov-2-like"
47218,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.092436975,"the, known, of, approximately, found, that, collected, were, by, a, and"
47219,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.092436975,"collected, by, a, of, the, found, that, were, and, approximately, known"
47220,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.092436975,"that, the, majority, of, were, in, to, with, a, and, market"
47221,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.092436975,"and, from, in, were, to, closely, related, the, of, coronavirus, bats"
47222,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.092436975,"in, a, of, were, found, to, be, with, novel, that, events"
47223,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.092436975,"that, of, from, to, a, sars-cov-2-like, in, dead, malayan, with, the"
47224,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.092436975,"in, of, a, to, with, found, novel, be, were, that, events"
47225,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.092436975,"in, of, to, the, from, bats, coronavirus, and, were, closely, related"
47226,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.092307692,"that, the, of, in, infect, a"
47227,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.092307692,"the, are, or, as, viruses, sars"
47228,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.092307692,"coronaviruses, and, the, reservoirs, of, three"
47229,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.092307692,"the, identified, of, most, over, and"
47230,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.092307692,"coronavirus, that, animals, and, with, for"
47231,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.092307692,"the, humans,, from, to, and, with"
47232,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.092307692,"to, the, of, and, may, have"
47233,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.092307692,"a, origin, of, by, that, sars-cov-2"
47234,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.092307692,"it, been, the, to, that, have"
47235,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.092307692,"and, to, of, the, other, a"
47236,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.092307692,"to, a, site, in, and, human"
47237,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.092307692,"the, and, to, a, of, other"
47238,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.092307692,"genome, was, that, the, virus, to"
47239,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.092307692,"the, and, to, suggesting, that, bat"
47240,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.092307692,"in, the, of, to, and, sequence"
47241,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.092307692,"to, the, have, of, and, that"
47242,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.092307692,"bats, are, of, and, zoonotic, as"
47243,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.092307692,"the, of, virus, to, as, is"
47244,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.092307692,"an, host, bats, and, in, the"
47245,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.092307692,"that, the, of, and, coronavirus, bats"
47246,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.092307692,"from, sars-cov-2, intermediate, hosts, to, the"
47247,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.092307692,"on, the, of, in, that, this"
47248,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.092307692,"a, of, animal, the, transmission, to"
47249,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.092307692,"that, the, as, and, mers-cov, sars-cov"
47250,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.092307692,"animals, and, that, for, with, coronavirus"
47251,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.092307692,"to, with, the, and, humans,, from"
47252,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.092307692,"in, a, and, are, to, sars-cov-2"
47253,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.092307692,"several, in, china, between, and, found"
47254,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.092307692,"that, a, origin, of, sars-cov-2, by"
47255,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.092307692,"are, and, the, from, a, in"
47256,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.092307692,"the, of, origin, a, and, diversity"
47257,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.092307692,"the, that, with, of, sars-cov-2, hypothesis"
47258,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.092307692,"in, the, of, a, at, and"
47259,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.092307692,"in, were, to, closely, related, the"
47260,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.092307692,"and, in, that, the, likely, sars-cov-2"
47261,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.092307692,"in, animals, but, of, the, and"
47262,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.092307692,"of, that, the, existence, a, from"
47263,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.092307692,"are, in, to, is, and, was"
47264,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.092307692,"as, the, for, viruses, of, and"
47265,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.092307692,"by, at, that, the, were, present"
47266,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.092307692,"of, the, analysis, that, is, to"
47267,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.092307692,"from, as, was, the, for, likely"
47268,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.092307692,"in, an, a, that, from, to"
47269,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.092307692,"no, have, to, the, evidence, of"
47270,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.092307692,"on, the, and, january, that, to"
47271,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.092307692,"of, and, a, to, that, in"
47272,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.092307692,"they, in, to, of, the, and"
47273,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.092307692,"to, other, of, and, in, their"
47274,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.092307692,"et, al., of, to, and, the"
47275,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.092307692,"sars-cov-2, be, the, and, to, virus"
47276,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.092307692,"from, the, of, that, a, to"
47277,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.092307692,"pangolin, to, the, that, for, of"
47278,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.092307692,"a, the, from, and, are, in"
47279,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.092307692,"in, the, but, and, of, animals"
47280,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.092307692,"are, was, to, and, is, in"
47281,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.092307692,"the, of, and, in, they, to"
47282,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.092307692,"of, the, has, are, to, virus"
47283,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.092307692,"the, are, of, genetic, is, they"
47284,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.092307692,"may, and, the, or, intermediate, for"
47285,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.092307692,"a, of, with, and, the, for"
47286,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.092307692,"bats, the, is, be, that, to"
47287,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.092307692,"the, of, that, wuhan, was, as"
47288,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.092307692,"the, that, positive, samples, from, market"
47289,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.092307692,"that, be, snakes, the, key, with"
47290,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.092307692,"the, of, to, and, which, as"
47291,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.092307692,"of, for, found, to, be, with"
47292,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.092307692,"as, that, sars-cov, and, mers-cov, the"
47293,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.092307692,"bat, cov, and, the, sars-cov-2, with"
47294,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.092307692,"the, a, to, called, animals, virus"
47295,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.092307692,"and, to, be, of, intermediate, host,"
47296,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.092307692,"of, that, had, the, to, virus"
47297,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.092307692,"of, covid-19, with, other, and, the"
47298,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.092307692,"the, reservoirs, of, coronaviruses, and, three"
47299,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.092307692,"and, of, to, intermediate, host,, be"
47300,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.092307692,"of, to, the, that, analysis, is"
47301,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.092307692,"the, of, is, similar, to, that"
47302,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.092307692,"was, that, the, wuhan, as, of"
47303,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.092307692,"the, of, more, to, that, and"
47304,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.092307692,"was, related, and, to, the, genome"
47305,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.092307692,"related, to, more, the, bat, and"
47306,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.092307692,"the, of, coronaviruses, however,, a, and"
47307,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.092307692,"in, sequence, which, that, sars-cov-2, to"
47308,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.092307692,"that, may, potential, intermediate, to, the"
47309,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.092307692,"a, at, the, of, in, that"
47310,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.092307692,"that, the, these, may, be, of"
47311,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.092307692,"of, the, in, with, huanan, seafood"
47312,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.092307692,"and, to, was, the, of, sars-cov-2"
47313,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.092307692,"sars-cov-2, sequence, to, which, that, in"
47314,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.092307692,"as, the, to, which, of, and"
47315,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.092307692,"the, it, for, sars-cov-2, in, a"
47316,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.092307692,"the, of, that, to, and, more"
47317,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.092307692,"the, of, from, with, a, sars-cov-2"
47318,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.092307692,"of, the, sars-cov-2, in, from, is"
47319,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.092307692,"is, the, with, sars-cov-2, that, bats"
47320,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.092307692,"of, with, and, the, were, in"
47321,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.092307692,"sars-cov-2, of, the, and, with, in"
47322,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.092307692,"the, has, as, from, to, and"
47323,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.092307692,"from, and, sars-cov-2, to, in, the"
47324,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.092307692,"the, and, from, nucleotide, sequence, with"
47325,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.092307692,"amino, acid, with, sars-cov-2, has, the"
47326,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.092307692,"the, is, and, in, one, at"
47327,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.092307692,"the, of, that, sars-cov-2, to, rbd"
47328,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.092307692,"the, and, or, may, intermediate, for"
47329,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.092307692,"snakes, be, the, with, that, key"
47330,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.092307692,"the, that, may, potential, intermediate, to"
47331,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.092307692,"the, that, have, been, to, it"
47332,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.092307692,"and, to, through, in, have, been"
47333,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.092307692,"a, and, sars-cov-2, to, in, the"
47334,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.092307692,"be, possible, to, of, and, some"
47335,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.092307692,"by, obtained, the, is, to, of"
47336,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.092307692,"the, and, also, ability, to, of"
47337,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.092307692,"the, of, and, that, a, laboratory"
47338,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.092307692,"in, the, of, with, huanan, seafood"
47339,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.092307692,"in, the, of, that, samples, from"
47340,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.092307692,"bats, and, the, from, southeast, in"
47341,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.092307692,"the, is, that, of, covid-19, at"
47342,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.092307692,"of, covid-19, a, to, the, in"
47343,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.092307692,"as, the, of, and, viruses, for"
47344,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.092307692,"bats, as, the, of, and, to"
47345,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.092307692,"in, the, and, that, to, all"
47346,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.092307692,"the, of, and, species, in, to"
47347,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.092307692,"a, of, that, the, in, infect"
47348,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.092307692,"that, the, in, as, a, of"
47349,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.092307692,"in, the, of, to, that, a"
47350,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.092307692,"a, of, in, the, viruses, to"
47351,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.092307692,"sars-cov-2, to, a, are, and, in"
47352,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.092307692,"the, genome, was, to, and, related"
47353,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.092307692,"the, are, with, and, in, at"
47354,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.092307692,"at, the, in, a, similar, to"
47355,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.092307692,"of, the, and, are, sars-, cov-2"
47356,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.092307692,"the, of, that, human, with, to"
47357,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.092307692,"site, and, to, a, in, human"
47358,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.092307692,"as, the, of, is, virus, to"
47359,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.092307692,"the, to, bat, and, more, related"
47360,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.092307692,"found, that, and, a, the, of"
47361,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.092307692,"to, a, of, animal, the, transmission"
47362,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.092307692,"of, the, reported, in, that, by"
47363,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.092307692,"from, the, and, nucleotide, sequence, with"
47364,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.092307692,"and, species, to, in, the, of"
47365,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.092307692,"that, the, of, with, to, human"
47366,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.092307692,"the, only, from, species, collected, in"
47367,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.092307692,"the, and, to, in, of, sequence"
47368,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.092307692,"a, and, of, at, the, in"
47369,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.092307692,"samples, from, the, that, of, in"
47370,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.092307692,"in, that, the, and, an, of"
47371,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.092307692,"of, the, covid-19, and, other, with"
47372,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.092307692,"of, natural, the, and, zoonotic, to"
47373,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.092307692,"at, the, and, in, is, one"
47374,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.092307692,"is, that, the, covid-19, of, at"
47375,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.092307692,"in, with, and, are, at, the"
47376,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.092307692,"a, for, sars-cov-2, it, the, in"
47377,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.092307692,"zoonotic, from, was, the, for, likely"
47378,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.092307692,"in, was, that, of, sars-cov-2, the"
47379,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.092307692,"on, january, the, that, and, to"
47380,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.092307692,"the, samples, from, market, positive, that"
47381,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.092307692,"the, to, that, all, in, and"
47382,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.092307692,"on, into, contact, with, to, a"
47383,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.092307692,"in, the, of, a, to, and"
47384,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.092307692,"a, of, the, that, or, to"
47385,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.092307692,"evidence, to, that, the, of, sars-cov-2"
47386,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.092307692,"had, for, the, of, have, been"
47387,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.092307692,"to, the, in, rhinolophus, that, a"
47388,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.092307692,"the, for, of, to, that, pangolin"
47389,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.092307692,"of, that, the, is, ace2, for"
47390,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.092307692,"by, a, of, the, that, and"
47391,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.092307692,"the, of, and, coronaviruses, a, however,"
47392,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.092307692,"of, from, a, with, sars-cov-2, the"
47393,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.092307692,"how, a, from, of, and, more"
47394,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.092307692,"the, and, a, these, coronaviruses, of"
47395,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.092307692,"been, in, and, to, have, through"
47396,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.092307692,"the, coronavirus, in, that, a, covid-19"
47397,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.092307692,"and, from, to, that, the, sars-"
47398,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.092307692,"from, the, existence, of, that, a"
47399,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.092307692,"the, that, for, ace2, is, of"
47400,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.092307692,"a, of, the, that, or, origin"
47401,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.092307692,"of, in, that, by, the, reported"
47402,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.092307692,"and, to, that, the, of, is"
47403,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.092307692,"the, of, to, that, have, and"
47404,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.092307692,"have, the, and, of, to, that"
47405,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.092307692,"a, rhinolophus, to, in, the, that"
47406,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.092307692,"the, that, a, in, coronavirus, covid-19"
47407,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.092307692,"in, of, and, have, similar, to"
47408,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.092307692,"that, of, to, in, with, the"
47409,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.092307692,"not, of, have, the, to, animals"
47410,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.092307692,"the, species, collected, from, only, in"
47411,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.092307692,"other, of, and, their, in, to"
47412,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.092307692,"bats, the, and, in, an, host"
47413,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.092307692,"of, to, be, possible, and, some"
47414,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.092307692,"of, from, a, and, more, how"
47415,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.092307692,"to, virus, but, bats, be, of"
47416,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.092307692,"a, into, contact, with, on, to"
47417,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.092307692,"a, virus, animals, to, the, called"
47418,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.092307692,"the, of, identical, and, to, sars-cov"
47419,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.092307692,"of, from, is, in, sars-cov-2, the"
47420,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.092307692,"obtained, from, in, the, is, of"
47421,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.092307692,"several, between, and, found, in, china"
47422,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.092307692,"from, in, bats, the, southeast, and"
47423,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.092307692,"the, not, to, have, of, animals"
47424,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.092307692,"over, the, identified, of, and, most"
47425,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.092307692,"to, the, has, from, and, as"
47426,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.092307692,"to, and, of, bats,, that, bat"
47427,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.092307692,"to, the, sars-cov-2, from, intermediate, hosts"
47428,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.092307692,"in, from, to, sars-cov-2, and, the"
47429,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.092307692,"has, the, amino, acid, with, sars-cov-2"
47430,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.092307692,"are, to, of, the, virus, has"
47431,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.092307692,"the, of, to, a, or, that"
47432,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.092307692,"of, that, the, origin, a, or"
47433,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.092307692,"had, been, of, the, for, have"
47434,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.092307692,"the, likely, was, from, for, as"
47435,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.092307692,"the, likely, was, for, zoonotic, from"
47436,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.092307692,"the, of, with, hypothesis, that, sars-cov-2"
47437,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.092307692,"are, they, is, of, the, genetic"
47438,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.092307692,"a, origin, of, the, diversity, and"
47439,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.092307692,"have, to, the, of, evidence, no"
47440,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.092307692,"in, the, is, that, has, a"
47441,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.092307692,"that, the, may, be, of, these"
47442,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.092307692,"be, that, the, bats, hosts, sars-cov-2"
47443,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.092307692,"virus, genome, the, was, to, that"
47444,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.092307692,"the, that, were, present, at, by"
47445,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.092307692,"the, of, to, obtained, is, by"
47446,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.092307692,"of, the, in, obtained, from, is"
47447,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.092307692,"study, found, that, the, of, to"
47448,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.092307692,"similar, to, have, in, of, and"
47449,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.092307692,"et, al., the, of, and, to"
47450,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.092307692,"a, for, the, of, and, with"
47451,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.092307692,"on, the, of, that, in, this"
47452,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.092307692,"that, the, of, a, laboratory, and"
47453,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.092307692,"a, and, with, sars-cov-2, in, the"
47454,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.092307692,"the, sars, as, are, viruses, or"
47455,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.092307692,"the, of, and, are, sars-, cov-2"
47456,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.092307692,"that, bats, is, with, sars-cov-2, the"
47457,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.092307692,"bats, coronavirus, the, of, and, that"
47458,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.092307692,"ratg13, is, the, bat, in, than"
47459,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.092307692,"cov, with, bat, the, sars-cov-2, and"
47460,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.092307692,"to, have, the, of, and, may"
47461,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.092307692,"the, for, of, to, that, and"
47462,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.092307692,"the, of, sars-cov-2, to, that, evidence"
47463,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.092307692,"a, of, the, found, that, and"
47464,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.092307692,"the, of, to, and, identical, sars-cov"
47465,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.092307692,"in, the, of, an, that, and"
47466,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.092307692,"but, be, virus, to, bats, of"
47467,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.092307692,"that, from, a, in, sars-cov-2, the"
47468,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.092307692,"of, natural, the, and, with, to"
47469,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.092307692,"found, to, be, with, of, for"
47470,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.092307692,"bats, are, as, of, and, zoonotic"
47471,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.092307692,"that, of, in, to, a, and"
47472,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.092307692,"in, of, to, the, that, was"
47473,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.092307692,"the, that, was, of, sars-cov-2, in"
47474,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.092307692,"in, a, similar, to, at, the"
47475,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.092307692,"the, sars-cov-2, likely, that, in, and"
47476,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.092307692,"the, from, that, to, sars-, and"
47477,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.092307692,"of, that, is, to, the, and"
47478,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.092307692,"that, bats, be, the, hosts, sars-cov-2"
47479,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.092307692,"in, bat, ratg13, the, is, than"
47480,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.092307692,"the, to, bat, and, suggesting, that"
47481,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.092307692,"the, ability, of, to, also, and"
47482,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.092307692,"the, of, coronaviruses, a, and, these"
47483,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.092307692,"also, that, the, of, suggesting, to"
47484,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.092307692,"and, to, of, is, in, bat"
47485,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.092307692,"of, that, bats,, to, bat, and"
47486,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.092307692,"study, that, the, to, of, found"
47487,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.092307692,"the, also, to, suggesting, that, of"
47488,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.092307692,"the, to, is, of, sars-, cov-2"
47489,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.092307692,"to, sars-cov-2, be, virus, and, the"
47490,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.092307692,"the, and, of, natural, zoonotic, to"
47491,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.092198582,"the, cases,, health, of, at, market, was, to, least, were, by, a, and"
47492,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.092198582,"a, the, at, least, was, health, and, market, of, were, to, cases,, by"
47493,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.092198582,"and, samples, at, the, it, that, for, of, in, study, from, a, by"
47494,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.092198582,"a, of, the, at, and, by, in, it, samples, for, study, that, from"
47495,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.092105263,"in, and, are, to, viruses, other, genetic"
47496,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.092105263,"of, and, a, which, to, in, human"
47497,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.092105263,"and, to, the, of, pre-, a, laboratory"
47498,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.092105263,"that, are, the, to, these, of, and"
47499,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.092105263,"of, and, were, intermediate, that, in, as"
47500,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.092105263,"in, the, of, a, coronavirus, that, for"
47501,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.092105263,"the, a, of, which, that, from, and"
47502,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.092105263,"of, that, the, origin, a, from, diversity"
47503,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.092105263,"also, a, the, of, in, that, to"
47504,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.092105263,"and, are, to, in, genetic, other, viruses"
47505,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.092105263,"at, are, and, in, some, the, to"
47506,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.092105263,"this, virus, the, covid-19, was, in, of"
47507,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.092105263,"the, of, were, as, a, for, from"
47508,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.092105263,"this, of, are, a, in, the, same"
47509,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.092105263,"the, was, from, a, market, to, of"
47510,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.092105263,"virus, in, is, at, the, of, on"
47511,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.092105263,"live, a, in, ways, the, that, to"
47512,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.092105263,"a, of, the, from, that, and, which"
47513,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.092105263,"and, from, to, that, the, of, coronavirus"
47514,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.092105263,"and, the, that, was, of, sars-cov-2, by"
47515,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.092105263,"and, at, the, that, in, from, a"
47516,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.092105263,"and, the, bat, also, together, with, into"
47517,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.092105263,"bats, the, be, of, to, and, may"
47518,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.092105263,"the, palm, intermediate, host, to, and, civet"
47519,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.092105263,"of, is, by, likely, to, through, that"
47520,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.092105263,"in, of, the, virus, covid-19, was, this"
47521,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.092105263,"and, the, was, of, in, this, by"
47522,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.092105263,"and, this, was, by, the, of, in"
47523,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.092105263,"and, with, to, or, bats, a, be"
47524,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.092105263,"a, for, coronavirus, the, of, in, that"
47525,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.092105263,"and, a, in, to, that, bat, coronaviruses"
47526,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.092105263,"sars-cov-2, a, of, sequences, the, and, that"
47527,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.092105263,"the, of, as, intermediate, was, that, to"
47528,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.092105263,"the, that, in, of, to, with, a"
47529,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.092105263,"a, of, the, from, were, for, as"
47530,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.092105263,"the, in, for, were, shared, with, a"
47531,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.092105263,"the, for, to, live, sars-related, that, with, bat, sars,, and, in, of, coronavirus, yunnan"
47532,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.092105263,"the, of, to, in, has, et, al."
47533,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.092105263,"the, and, from, in, out, as, to"
47534,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.092105263,"from, as, and, to, the, sars-cov-2, in"
47535,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.092105263,"the, rbd, and, to, that, these, of"
47536,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.092105263,"sars-cov-2, of, the, and, with, in, ace2"
47537,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.092105263,"that, the, sequences, of, sars-cov-2, and, a"
47538,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.092105263,"the, sars-cov-2, to, therefore,, in, of, natural"
47539,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.092105263,"and, the, of, viruses, as, bats, for"
47540,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.092105263,"in, a, of, the, are, this, same"
47541,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.092105263,"the, of, by, in, a, similar, same"
47542,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.092105263,"the, of, and, species, a, in, this"
47543,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.092105263,"and, the, of, in, this, a, by"
47544,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.092105263,"and, this, by, the, of, in, a"
47545,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.092105263,"together, with, bat, and, also, into, the"
47546,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.092105263,"bats, as, the, for, viruses, of, and"
47547,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.092105263,"is, likely, that, of, to, through, by"
47548,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.092105263,"of, similar, by, a, in, the, same"
47549,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.092105263,"virus, in, is, similar, the, of, on"
47550,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.092105263,"to, of, is, that, similar, related, in"
47551,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.092105263,"a, of, to, the, was, from, market"
47552,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.092105263,"and, that, of, were, in, intermediate, as"
47553,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.092105263,"out, in, to, the, from, and, as"
47554,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.092105263,"this, of, and, a, species, in, the"
47555,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.092105263,"virus, from, in, with, the, sequence, of"
47556,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.092105263,"to, the, and, palm, civet, intermediate, host"
47557,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.092105263,"the, of, that, as, intermediate, was, to"
47558,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.092105263,"and, of, the, to, live, in, with, sars,, that, yunnan, bat, for, sars-related, coronavirus"
47559,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.092105263,"were, a, for, shared, with, the, in"
47560,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.092105263,"the, to, suggesting, of, natural, origin, and"
47561,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.092105263,"in, the, and, at, are, to, some"
47562,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.092105263,"that, the, in, ways, to, live, a"
47563,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.092105263,"that, are, the, to, in, this, and"
47564,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.092105263,"the, of, and, that, sars-cov-2, was, by"
47565,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.092105263,"that, the, in, and, from, at, a"
47566,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.092105263,"and, by, this, the, was, in, of"
47567,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.092105263,"a, origin, of, the, from, that, diversity"
47568,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.092105263,"a, of, have, and, the, to, animals"
47569,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.092105263,"bats, are, natural, of, and, that, in"
47570,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.092105263,"the, of, have, to, in, animals, was"
47571,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.092105263,"bats, are, more, to, of, on, and"
47572,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.092105263,"the, and, bats, may, be, of, to"
47573,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.092105263,"et, al., has, the, of, to, in"
47574,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.092105263,"and, a, to, bats, be, with, or"
47575,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.092105263,"the, was, to, have, in, of, animals"
47576,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.092105263,"at, the, of, in, on, virus, is"
47577,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.092105263,"the, of, on, is, in, virus, similar"
47578,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.092105263,"the, of, virus, from, sequence, in, with"
47579,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.092105263,"to, the, have, of, and, animals, a"
47580,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.092105263,"laboratory, and, to, of, the, a, pre-"
47581,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.092105263,"in, to, the, sars-cov-2, from, and, as"
47582,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.092105263,"to, bats, of, and, are, more, on"
47583,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.092105263,"and, in, to, that, coronaviruses, are, of"
47584,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.092105263,"the, and, are, of, that, these, to"
47585,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.092105263,"therefore,, the, of, natural, sars-cov-2, to, in"
47586,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.092105263,"the, and, of, suggesting, natural, origin, to"
47587,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.092105263,"are, and, this, in, the, that, to"
47588,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.092105263,"and, which, to, a, of, in, human"
47589,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.092105263,"that, bats, are, natural, of, and, in"
47590,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.092105263,"the, of, to, that, coronavirus, from, and"
47591,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.092105263,"a, and, coronaviruses, bat, to, that, in"
47592,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.092105263,"these, and, the, of, rbd, to, that"
47593,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.092105263,"coronaviruses, in, are, to, that, of, and"
47594,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.092105263,"of, related, is, in, similar, to, that"
47595,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.092105263,"sars-cov-2, ace2, in, of, and, the, with"
47596,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.091954023,"the, are, in, as, viruses, horseshoe, sars, bats"
47597,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.091954023,"in, one, to, whole, genome, more, than, virus"
47598,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.091954023,"in, the, of, which, that, sars-cov-2, to, virus"
47599,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.091954023,"a, to, in, the, which, that, not, human"
47600,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.091954023,"and, the, of, bat, to, viruses, are, that"
47601,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.091954023,"sars-cov-2, origin, of, to, have, that, and, the"
47602,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.091954023,"to, a, animal, in, wet, china, were, and"
47603,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.091954023,"a, of, genetic, to, has, that, by, the"
47604,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.091954023,"most, of, the, have, in, that, was, by"
47605,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.091954023,"and, the, of, to, that, which, virus, is"
47606,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.091954023,"that, to, the, by, a, of, genetic, has"
47607,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.091954023,"and, an, to, the, of, on, was, animal"
47608,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.091954023,"and, from, to, at, the, market, in, a"
47609,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.091954023,"that, a, the, virus, was, of, at, all"
47610,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.091954023,"sars-cov-2, of, which, to, virus, that, in, the"
47611,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.091954023,"for, and, with, from, the, of, its, a"
47612,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.091954023,"a, of, in, that, with, the, transmission, to"
47613,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.091954023,"that, the, sars-cov-2, may, with, in, of, and"
47614,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.091954023,"an, bat, to, in, the, of, and, species"
47615,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.091954023,"the, viruses, and, are, of, bat, that, to"
47616,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.091954023,"the, virus, which, is, to, that, of, and"
47617,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.091954023,"at, all, that, the, virus, was, of, a"
47618,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.091954023,"of, the, early, cases, have, in, that, was"
47619,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.091954023,"that, transmission, of, to, a, in, with, the"
47620,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.091954023,"of, december, a, to, and, the, were, in"
47621,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.091954023,"one, virus, more, than, to, in, whole, genome"
47622,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.091954023,"were, to, a, and, wet, animal, in, china"
47623,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.091954023,"bat, and, species, to, an, in, the, of"
47624,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.091954023,"the, sars, as, are, viruses, in, horseshoe, bats"
47625,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.091954023,"on, the, of, and, an, animal, was, to"
47626,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.091954023,"the, in, and, to, from, at, a, market"
47627,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.091954023,"with, the, of, a, for, its, from, and"
47628,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.091954023,"in, december, the, of, a, were, to, and"
47629,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.091954023,"and, into, since, or, a, be, then, by"
47630,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.091954023,"which, to, human, a, that, not, in, the"
47631,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.091954023,"the, that, was, have, most, in, by, of"
47632,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.091954023,"that, the, was, early, cases, of, in, have"
47633,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.091954023,"since, and, then, be, or, into, a, by"
47634,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.091954023,"of, and, a, to, that, in, such, as"
47635,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.091954023,"sars-cov-2, may, in, of, and, that, the, with"
47636,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.091954023,"such, as, and, to, of, that, in, a"
47637,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.091836735,"that, of, to, without, an, a, in, sars-cov-2, the"
47638,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.091836735,"the, of, that, in, a, human, cells, and, to"
47639,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.091836735,"the, that, to, have, its, of, can, and, sars-cov-2"
47640,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.091836735,"the, animals, to, for, as, that, virus, and, palm"
47641,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.091836735,"in, to, yunnan, province,, the, from, which, at, previously"
47642,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.091836735,"the, of, from, that, two, at, to, least, a"
47643,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.091836735,"in, the, of, as, at, virus, to, and, more"
47644,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.091836735,"the, of, its, can, to, that, have, and, sars-cov-2"
47645,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.091836735,"it, was, that, the, sars-cov-2, and, to, is, by"
47646,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.091836735,"in, the, role, of, was, a, that, were, to"
47647,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.091836735,"the, of, cases, with, huanan, seafood, market, and, at"
47648,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.091836735,"the, that, was, to, is, by, it, and, sars-cov-2"
47649,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.091836735,"in, first, that, at, market, was, were, a, and"
47650,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.091836735,"cases, the, huanan, market,, of, suggesting, to, that, be"
47651,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.091836735,"the, was, for, a, that, and, in, of, taken"
47652,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.091836735,"this, that, the, virus, was, of, in, but, to"
47653,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.091836735,"a, as, from, for, the, were, of, and, bats,"
47654,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.091836735,"sars-cov-2, of, to, a, that, in, an, without, the"
47655,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.091836735,"an, to, as, from, in, the, addition, and, also"
47656,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.091836735,"in, the, of, from, that, raccoon, at, market, was"
47657,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.091836735,"the, of, species, horseshoe, to, bats, as, intermediate, and"
47658,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.091836735,"this, in, the, of, that, was, to, but, virus"
47659,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.091836735,"a, at, least, two, to, that, the, of, from"
47660,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.091836735,"that, was, first, and, in, were, at, a, market"
47661,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.091836735,"the, of, raccoon, in, from, market, that, was, at"
47662,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.091836735,"the, in, of, similar, to, that, was, also, virus"
47663,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.091836735,"found, that, also, similar, to, and, a, the, of"
47664,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.091836735,"is, the, coronavirus, known, to, in, of, less, than"
47665,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.091836735,"as, in, the, of, and, at, to, more, virus"
47666,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.091836735,"that, the, role, of, in, was, to, were, a"
47667,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.091836735,"the, horseshoe, bats, species, to, as, of, intermediate, and"
47668,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.091836735,"coronaviruses, that, were, to, in, bats, south, and, china"
47669,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.091836735,"that, the, virus, in, bats, and, to, intermediate, of"
47670,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.091836735,"at, the, to, which, previously, in, from, yunnan, province,"
47671,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.091836735,"the, of, at, this, a, virus, circulating, in, for"
47672,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.091836735,"the, was, in, and, that, taken, for, a, of"
47673,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.091836735,"that, the, closest, with, at, of, virus, and, to"
47674,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.091836735,"the, of, were, as, a, for, from, bats,, and"
47675,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.091836735,"in, addition, to, the, also, from, and, as, an"
47676,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.091836735,"or, of, and, the, in, bats, may, transmission, viruses"
47677,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.091836735,"animals, as, that, virus, to, for, and, the, palm"
47678,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.091836735,"in, a, of, for, were, to, infected, with, that"
47679,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.091836735,"of, cases, be, to, the, huanan, market,, suggesting, that"
47680,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.091836735,"this, the, in, that, more, likely, for, sars-cov-2, than"
47681,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.091836735,"the, huanan, seafood, with, at, and, market, of, cases"
47682,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.091836735,"in, to, that, bats, and, were, coronaviruses, china, south"
47683,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.091836735,"in, the, of, that, also, virus, was, similar, to"
47684,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.091836735,"of, cells, to, human, a, that, in, and, the"
47685,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.091836735,"the, of, in, to, that, bats, intermediate, and, virus"
47686,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.091836735,"bats, in, the, or, and, of, transmission, may, viruses"
47687,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.091836735,"bats, on, can, be, of, are, to, as, and"
47688,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.091836735,"can, be, to, bats, of, and, are, as, on"
47689,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.091836735,"the, and, also, has, in, to, these, are, of"
47690,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.091836735,"the, for, that, in, this, sars-cov-2, more, likely, than"
47691,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.091836735,"the, of, found, that, also, similar, to, a, and"
47692,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.091836735,"in, a, of, the, for, circulating, this, at, virus"
47693,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.091836735,"to, in, a, for, of, with, that, infected, were"
47694,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.091836735,"in, less, than, the, known, of, to, coronavirus, is"
47695,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.091836735,"the, these, of, are, to, and, in, has, also"
47696,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.091743119,"the, of, have, a, which, to, in, and, various, virus"
47697,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.091743119,"the, a, in, to, that, with, and, for, coronaviruses, east"
47698,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.091743119,"from, the, samples,, a, live, and, in, of, an, including"
47699,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.091743119,"the, from, and, in, a, to, that, infected, at, virus"
47700,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.091743119,"of, the, have, live, animals, in, were, with, that, may"
47701,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.091743119,"that, the, with, in, may, have, live, animals, were, of"
47702,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.091743119,"related, to, events, in, may, with, sars-cov-2, the, bat, and"
47703,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.091743119,"that, a, the, an, over, humans, with, of, in, to"
47704,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.091743119,"sars-cov-2, and, the, to, related, in, with, bat, events, may"
47705,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.091743119,"the, from, on, and, with, by, of, a, to, at"
47706,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.091743119,"that, of, to, humans, an, a, in, with, over, the"
47707,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.091743119,"not, a, of, but, also, have, zoonotic, the, to, different"
47708,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.091743119,"the, also, a, in, to, suggesting, that, not, of, but"
47709,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.091743119,"of, three, at, the, in, a, similar, to, that, animal"
47710,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.091743119,"in, the, a, east, that, coronaviruses, to, and, with, for"
47711,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.091743119,"in, the, live, samples,, including, from, an, and, a, of"
47712,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.091743119,"a, of, the, at, wiv, also, by, that, to, virus"
47713,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.091743119,"in, this, it, be, that, the, recombination, and, of, bat"
47714,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.091743119,"of, which, various, to, a, virus, have, in, and, the"
47715,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.091743119,"that, the, virus, in, and, to, from, infected, at, a"
47716,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.091743119,"the, by, from, a, at, and, to, of, on, with"
47717,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.091743119,"a, zoonotic, the, of, different, also, not, have, but, to"
47718,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.091743119,"the, wiv, also, to, a, virus, that, by, of, at"
47719,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.091743119,"in, the, of, bat, be, and, that, recombination, this, it"
47720,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.091743119,"in, the, animal, of, that, three, at, similar, to, a"
47721,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.091743119,"that, a, the, of, in, suggesting, also, not, but, to"
47722,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.091666667,"in, with, the, by, and, to, that, of, bat, closest, as"
47723,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.091666667,"the, to, that, with, bat, as, and, by, in, of, closest"
47724,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.091503268,"with, the, and, for, of, to, that, were, in, selling, between, sars-cov-2, live, animal"
47725,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.091503268,"between, sars-cov-2, and, of, the, to, selling, live, animal, in, were, with, that, for"
47726,"The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.091370558,"the, of, is, natural, a, been, coronavirus, animal, since, to, humans, it, that, first, human, such, as, by"
47727,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).",0.091370558,"that, it, to, human, such, as, first, the, animal, coronavirus, humans, by, a, of, is, since, been, natural"
47728,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.090909091,"bats, of, reservoir"
47729,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.090909091,"of, viruses, a, in"
47730,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.090909091,"bats, of, a, large, in"
47731,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.090909091,"in, the, a, that, from, and"
47732,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.090909091,"a, of, the, from, that, and, in"
47733,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.090909091,"in, the, from, and, a, of"
47734,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.090909091,"from, in, the, of, that, a"
47735,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.090909091,"pangolins, from, and, the, of"
47736,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.090909091,"in, the, of, a, from, that"
47737,"This suggests that the BANAL series may be able to directly infect  

humans.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.090909091,"that, the, directly, infect"
47738,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.090909091,"a, of, the, that, or, data"
47739,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.090909091,"coronaviruses, a, to, and"
47740,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.090909091,"a, human, viral, and"
47741,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.090909091,"the, virus, and, humans, from"
47742,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.090909091,"the, of, natural, from, and"
47743,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.090909091,"from, the, and, 2"
47744,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.090909091,"in, a, are"
47745,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.090909091,"a, of, in"
47746,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.090909091,"a, of, viruses, but"
47747,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.090909091,"animal, are, of"
47748,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.090909091,"in, of, coronaviruses"
47749,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.090909091,"an, of"
47750,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.090909091,"are, the, viruses"
47751,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.090909091,"the, are, from"
47752,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.090909091,"the, from, in, sars, or, as"
47753,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.090909091,"from, bats, the"
47754,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.090909091,"the, of, also, coronaviruses"
47755,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.090909091,"and, species, be, to, bats"
47756,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.090909091,"and, the, of, to, be"
47757,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.090909091,"bats, are, to, of, and"
47758,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.090909091,"one, virus, more, than"
47759,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.090909091,"virus, that, of, and, coronavirus"
47760,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.090909091,"of, virus, and, with, coronavirus"
47761,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.090909091,"of, and, that, with, or, for"
47762,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.090909091,"bats, for, of, and"
47763,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.090909091,"that, virus, animals, with, were"
47764,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.090909091,"of, that, more, with, than"
47765,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.090909091,"of, that, corona-, virus, for"
47766,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.090909091,"genetic, sequences, and"
47767,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.090909091,"genetic, many, and"
47768,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.090909091,"genetic, to, and"
47769,"Coronaviruses are naturally hosted and developmentally 

formed by bats.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.090909091,"coronaviruses, and"
47770,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.090909091,"and, to, in, have"
47771,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.090909091,"have, sars-cov, and"
47772,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.090909091,"in, and, bat"
47773,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.090909091,"sars-cov, emerged, in"
47774,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.090909091,"and, which, in"
47775,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.090909091,"of, in, to, and"
47776,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.090909091,"sars-cov, and, to, bats, of"
47777,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.090909091,"bats, to, and"
47778,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.090909091,"in, of, and"
47779,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.090909091,"sars-cov, and, to, of, sars-cov-2, in"
47780,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.090909091,"sars-cov-2, and, to, in"
47781,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.090909091,"identified, from, bats, of"
47782,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.090909091,"the, sars, are"
47783,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.090909091,"the, to, very"
47784,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.090909091,"to, genetic, similar, the"
47785,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.090909091,"the, and, very"
47786,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.090909091,"one, more, than, virus"
47787,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.090909091,"sars-cov-2, than, in"
47788,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.090909091,"in, to, is, virus"
47789,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.090909091,"virus, one, to, sars-cov-2"
47790,"a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.090909091,"a, coronavirus"
47791,"bats are also important reservoir species for a great 

range of coronaviruses","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.090909091,"for, a"
47792,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.090909091,"and, a, is"
47793,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.090909091,"is, coronavirus, a, nature"
47794,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.090909091,"of, the, in, bats"
47795,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.090909091,"the, in, china, of"
47796,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.090909091,"also, of, in, the"
47797,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.090909091,"of, into, from, and, to"
47798,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.090909091,"may, of, and, cats, the, with"
47799,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.090909091,"the, of, spillover, to, virus"
47800,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.090909091,"the, and, of, spillover, to"
47801,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.090909091,"to, emergence, the, of, and"
47802,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.090909091,"the, of, to, with, bat"
47803,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.090909091,"in, the, a, was, to, with"
47804,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.090909091,"in, 2020,, the, a, of, sars-cov-2"
47805,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.090909091,"in, the, of, a, sars-cov-2, to"
47806,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.090909091,"sars-cov-2, a, is, in"
47807,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.090909091,"the, of, to, as, is"
47808,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.090909091,"sars-cov-2, the, with, of, to"
47809,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.090909091,"coronavirus, have, been"
47810,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.090909091,"that, have, coronavirus, of"
47811,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.090909091,"that, a, of, sars-cov-2, about"
47812,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.090909091,"sars-cov-2, be, a, that"
47813,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.090909091,"that, a, of, been"
47814,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.090909091,"been, that, sars-cov-2, a"
47815,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.090909091,"that, of, origin, be"
47816,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.090909091,"that, sars-cov-2, be"
47817,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.090909091,"closest, to, genetic, sars-cov-2, the"
47818,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.090909091,"have, been, coronavirus"
47819,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.090909091,"have, that, the, virus, in, and, to, a"
47820,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.090909091,"human, ace2, and, virus, the, covid-19, in, of"
47821,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.090909091,"of, and, a, which, to, that, in, such, human"
47822,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.090909091,"of, human, coronaviruses, and, which, in"
47823,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.090909091,"have, a, which, is, of"
47824,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.090909091,"the, other, of, in, spike, and, a"
47825,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.090909091,"sequence, in, the, a, from, that"
47826,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.090909091,"the, was, in, that, a"
47827,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.090909091,"the, virus, by, genetic, is"
47828,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.090909091,"a, the, also, by, that, virus"
47829,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.090909091,"sars-cov-2, was, from, that"
47830,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.090909091,"a, sars-cov-2, by, the, in"
47831,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.090909091,"the, from, by, a, virus"
47832,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.090909091,"many, genetic, and"
47833,hese close genetic relations suggest that they all have their ecological origin in bat populations,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.090909091,"genetic, that, their"
47834,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.090909091,"virus, shares, with"
47835,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.090909091,"that, a, and, fully"
47836,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.090909091,"are, the, of, and, that, to"
47837,"All human coronaviruses have animal origins, namely, natu- 

ral hosts","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.090909091,"all, human, coronaviruses"
47838,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.090909091,"of, the, are, viruses"
47839,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.090909091,"are, the, of, coronaviruses"
47840,"unnatural origin of SARS-CoV-2, but these people are 

simply wrong","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.090909091,"of, these, are"
47841,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.090909091,"the, of, to, human, that"
47842,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.090909091,"of, that, the, bat, these"
47843,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.090909091,"highly, identical, the, to"
47844,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.090909091,"that, have, the, bat"
47845,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.090909091,"the, to, identical, that"
47846,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.090909091,"the, genome, with, bat"
47847,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.090909091,"that, the, host"
47848,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.090909091,"identified, the, bat"
47849,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.090909091,"the, with, sars-cov-2, genome"
47850,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.090909091,"sars-cov-2, that, the, with, as"
47851,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.090909091,"that, sars-cov-2, to, the, with"
47852,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.090909091,"the, natural, sars-cov-2, to"
47853,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.090909091,"the, sars-cov-2, belongs"
47854,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.090909091,"the, as, host, that, identical, to"
47855,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.090909091,"the, natural, with, to"
47856,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.090909091,"the, a, was, that, to"
47857,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.090909091,"sequence, the, of, a, that"
47858,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.090909091,"that, to, sars-cov-2, found"
47859,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.090909091,"a, of, the, that, to"
47860,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.090909091,"and, of, natural, virus"
47861,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.090909091,"virus, genome, bat, and"
47862,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.090909091,"host, of, as"
47863,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.090909091,"of, been, origin, and"
47864,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.090909091,"and, of, virus"
47865,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.090909091,"has, virus, origin, of"
47866,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.090909091,"the, are, viruses"
47867,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.090909091,"a, and, the, of"
47868,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.090909091,"including, the, and, of"
47869,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.090909091,"the, of, and, natural, a"
47870,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.090909091,"virus, genome, and, bat"
47871,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.090909091,"the, genome, to, human, bat"
47872,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.090909091,"and, bat, suggesting, the, same"
47873,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.090909091,"the, sars-cov-2, showed, identity"
47874,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.090909091,"to, and, that, ratg13, bat"
47875,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.090909091,"and, that, in, of"
47876,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.090909091,"of, and, with, sars-cov-2"
47877,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.090909091,"sars-cov-2, of, and, with, or"
47878,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.090909091,"and, sars-cov-2, transmission, between, with"
47879,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.090909091,"of, including, sars-cov-2"
47880,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.090909091,"and, of, between, with"
47881,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.090909091,"are, of, to"
47882,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.090909091,"are, of, most"
47883,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.090909091,"to, most, of"
47884,Bats are likely reservoir hosts for SARS-CoV-2,Originating from reservoir of bat,0.090909091,reservoir
47885,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",Originating from reservoir of bat,0.090909091,"bat, from"
47886,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.090909091,"that, of, to, humans, sars-cov-2, the"
47887,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.090909091,"can, be, that, to"
47888,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.090909091,"of, have, and, the, to, including"
47889,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.090909091,"the, and, decreased, to, that, of"
47890,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.090909091,"a, the, as, of, human"
47891,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.090909091,"that, a, human"
47892,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.090909091,"in, the, of, a, that"
47893,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.090909091,"a, of, the, has, that"
47894,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.090909091,"that, in, bats"
47895,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.090909091,"that, the, of, bats, as"
47896,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.090909091,"the, zoonotic, as, of, and"
47897,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.090909091,"have, been, and, the, of"
47898,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.090909091,"and, have, the, they, are"
47899,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.090909091,"is, that, a, in, their"
47900,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.090909091,"the, that, in, a, as, to"
47901,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.090909091,"with, and, also, into, the"
47902,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.090909091,"of, the, virus, and, with, coronavirus"
47903,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.090909091,"in, the, of, a, to, as, with, be, and, that, recombination, thus"
47904,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.090909091,"is, that, of, a, coronavirus"
47905,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.090909091,"is, to, in, the, host, with"
47906,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.090909091,"in, the, that, a, to"
47907,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.090909091,"sequence, in, the, a, that"
47908,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.090909091,"a, similarity, to"
47909,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.090909091,"a, the, that, to, virus"
47910,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.090909091,"to, the, a, virus"
47911,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.090909091,"sars-cov-2,, the, of"
47912,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.090909091,"the, in, as, of"
47913,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.090909091,"the, of, from, intermediate"
47914,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.090909091,"of, sars-cov-2, humans,, the"
47915,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.090909091,"of, phylogenetic, the, to"
47916,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.090909091,"the, in, as, of, and"
47917,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.090909091,"in, wuhan, the, however,"
47918,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.090909091,"of, in, the, and, has, been"
47919,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.090909091,"has, and, in, before"
47920,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.090909091,"however,, the, and, in, of"
47921,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.090909091,"that, the, of, market, in, to, were"
47922,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.090909091,"the, of, infected, to, that, this, in, is"
47923,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.090909091,"that, the, to, in, this, of, origin"
47924,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.090909091,"the, that, likely, covid-19"
47925,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.090909091,"to, on, the, in, that"
47926,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.090909091,"that, the, number, of"
47927,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.090909091,"of, on, the, zoonotic, to, in"
47928,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.090909091,"in, wet, market"
47929,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.090909091,"a, wet, market, in, animal, to"
47930,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.090909091,"the, of, and, a, to"
47931,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.090909091,"be, coronavirus, to"
47932,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.090909091,"a, is, to, the"
47933,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.090909091,"the, a, animal, coronavirus"
47934,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.090909091,"of, the, later"
47935,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.090909091,"the, of, a, to, animal, and"
47936,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.090909091,"a, the, is, to, of"
47937,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.090909091,"most, of, are"
47938,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.090909091,"bats, are, the, of, and, that"
47939,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.090909091,"that, the, been, by"
47940,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.090909091,"that, species, of, and"
47941,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.090909091,"the, has, of, that, and"
47942,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.090909091,"dents, the, that, and"
47943,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","All human coronaviruses have animal origins, namely, natu- 

ral hosts",0.090909091,"all, coronaviruses, human"
47944,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.090909091,"natural, and, the"
47945,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.090909091,"the, be, hosts"
47946,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.090909091,"the, and, may"
47947,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.090909091,"sars-, bats"
47948,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.090909091,"of, and, bats"
47949,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.090909091,"bats, and"
47950,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.090909091,"natural, of, the, beta-coronaviruses"
47951,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.090909091,"the, sars-cov, from, animals"
47952,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.090909091,"the, and, can, to"
47953,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.090909091,"the, and, disease, that"
47954,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.090909091,"to, the, virus, that, from, for, as"
47955,"insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.090909091,"from, as, camels,, and"
47956,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.090909091,"animals, and, can, to"
47957,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.090909091,"that, species, the, natural"
47958,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.090909091,"the, that, from, as"
47959,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.090909091,"that, to, and, respectively"
47960,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.090909091,"the, that, as, for"
47961,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.090909091,"through, the, covid-19, sars-cov-2"
47962,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.090909091,"sars-cov-2, through, with, the"
47963,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.090909091,"to, highly, identical, the"
47964,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.090909091,"at, the, was, from"
47965,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.090909091,"the, from, to, which"
47966,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.090909091,"is, to, the, was"
47967,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.090909091,"ratg13,, the, is, to"
47968,COVID-19 is a potential zoonotic disease,zoonotic origins of SARS-CoV-2 by natural evolution,0.090909091,zoonotic
47969,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",zoonotic origins of SARS-CoV-2 by natural evolution,0.090909091,"of, zoonotic"
47970,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",zoonotic origins of SARS-CoV-2 by natural evolution,0.090909091,"zoonotic, of"
47971,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.090909091,"the, origin, to, sars-cov-2"
47972,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.090909091,"is, the, a"
47973,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.090909091,"the, sequence, sars-cov-2, to"
47974,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.090909091,"the, sars-cov-2, with, sequence"
47975,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.090909091,"a, from, the, is, to"
47976,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.090909091,"the, of, sars-cov-2,"
47977,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.090909091,"the, and, which"
47978,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.090909091,"of, to, the, which"
47979,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.090909091,"coronaviruses, and, to, the, of"
47980,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.090909091,"the, of, to, which"
47981,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.090909091,"including, and, of, coronaviruses"
47982,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.090909091,"and, sars-cov, the, in"
47983,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.090909091,"and, in, to, the"
47984,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.090909091,"the, from, in"
47985,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.090909091,"animals, from, sars-cov, the"
47986,"this one jumped from bats origin  

into humans","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.090909091,"from, humans"
47987,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.090909091,"was, in, humans"
47988,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.090909091,"sars-cov-2, bat, the"
47989,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.090909091,"of, bat, in, the"
47990,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.090909091,"the, of, and, that, with, to"
47991,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.090909091,"the, is, that, of, to, and, with"
47992,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.090909091,"that, the, are"
47993,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","civet cats and raccoon dogs  

are the intermediate hosts",0.090909091,"intermediate, and, the"
47994,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.090909091,"a, the, in, was, to, with"
47995,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.090909091,"was, that, the, to, a"
47996,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.090909091,"the, from, at, for, that"
47997,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.090909091,"and, that, the, novel, to"
47998,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.090909091,"are, a, the, health, coronaviruses"
47999,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.090909091,"at, the, and, in, from, to"
48000,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.090909091,"to, a, in, the, for"
48001,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.090909091,"highly, that, a, the, at, from"
48002,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.090909091,"and, a, in, the, for, to"
48003,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.090909091,"can, to, and, the"
48004,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.090909091,"of, are, and, infections"
48005,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.090909091,"sars-cov-2, and, animal"
48006,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.090909091,"to, the, and, be"
48007,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.090909091,"of, sars-cov-2, to, be"
48008,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","with the first case being linked to  

a seafood market",0.090909091,"the, a"
48009,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","with the first case being linked to  

a seafood market",0.090909091,"to, the, with"
48010,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.090909091,"the, sars-cov-2, to, be, in, this, of"
48011,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.090909091,"sars-cov-2, be, of, the, to, in"
48012,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.090909091,"and, in, which"
48013,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.090909091,"disease, that, and, the"
48014,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.090909091,"the, which, and"
48015,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.090909091,"the, that, and"
48016,"this one jumped from bats origin  

into humans","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.090909091,"one, origin"
48017,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.090909091,"the, a, and, which"
48018,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.090909091,"a, in, the, and, that"
48019,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.090909091,"the, and, in, that"
48020,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.090909091,"been, that, the, by"
48021,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.090909091,"that, not, the, was"
48022,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.090909091,"that, it, the, had, out, by, a, been"
48023,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.090909091,"the, that, a, it"
48024,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.090909091,"scientists, that, a, was, the"
48025,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.090909091,"the, virus, other, was"
48026,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.090909091,"it, that, a"
48027,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.090909091,"that, sars-cov-2, has, through, and"
48028,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.090909091,"sars-, cov-2, has, its"
48029,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.090909091,"that, sars-, cov-2, and, at"
48030,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.090909091,"to, that, sars-cov-2, and, including"
48031,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.090909091,"with, sars-, and, to, sars-cov-2, at"
48032,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.090909091,"sars-, cov-2, to, that, its"
48033,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.090909091,"genetic, been, to, in"
48034,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.090909091,"genetic, and, have, likely, bat"
48035,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.090909091,"and, identified, in, a, china"
48036,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.090909091,"could, sars-cov-2, are, in, an"
48037,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.090909091,"similarity, between, sars-cov-2, and, bat"
48038,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.090909091,"the, of, humans, that"
48039,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.090909091,"of, to, a, from"
48040,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.090909091,"that, sars-cov-2, through, has, and"
48041,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.090909091,"the, that, sars-cov-2, genomic, and, are"
48042,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.090909091,"sars-cov-2, has, genome"
48043,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.090909091,"sars-cov-2, the, that, natural, selection"
48044,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.090909091,"the, has, are, that, have"
48045,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.090909091,"studies, that, such, sars-cov-2"
48046,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.090909091,"the, that, are, natural, sars-cov-2"
48047,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.090909091,"and, that, the, are, natural, sars-cov-2"
48048,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.090909091,"that, of, have, coronavirus"
48049,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.090909091,"have, that, bat, the"
48050,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.090909091,"the, of, from, at"
48051,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.090909091,"the, of, and, that, at"
48052,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.090909091,"and, the, was, from"
48053,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.090909091,"they, of, the, and, was"
48054,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.090909091,"from, the, was, that, bat, and, of, coronavirus, at"
48055,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.090909091,"suggest, that, the, studies"
48056,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.090909091,"the, of, spillover"
48057,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.090909091,"coronaviruses,, sars-cov-2, from"
48058,"a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.090909091,"with, sars-cov-2"
48059,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.090909091,"s, with, sars-cov-2"
48060,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.090909091,"and, closely, related"
48061,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.090909091,"a, of, and, that, the, from, in"
48062,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.090909091,"genomic, that, sars-cov-2, and, are, the"
48063,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.090909091,"the, that, are, sars-cov-2, in, and"
48064,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.090909091,"are, a, genomic, in, sars-cov-2, the, and"
48065,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.090909091,"a, that, genomic, the, sars-cov-2, in"
48066,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.090909091,"the, that, sars-cov-2, at, of, and"
48067,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.090909091,"from, the, at, of"
48068,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.090909091,"sars-cov-2, from, the, intermediate"
48069,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.090909091,"sars-cov-2, of, the, intermediate, for"
48070,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.090909091,"intermediate, for, sars-cov-2, humans, the"
48071,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.090909091,"the, of, zoonotic, sars-cov-2"
48072,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.090909091,"the, animals, are, to, of, that, and, market"
48073,"preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.090909091,"that, transmission, of"
48074,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.090909091,"and, that, the, at, of"
48075,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.090909091,"the, that, in, humans, market"
48076,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.090909091,"with, and, into, the"
48077,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.090909091,"the, hypothesis, that, of, and"
48078,"Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.090909091,"presence, of, animal, in"
48079,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.090909091,"in, the, of, at, that, humans, and"
48080,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.090909091,"are, in, a"
48081,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.090909091,"the, to, in, a"
48082,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.090909091,"to, related, that, are"
48083,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.090909091,"the, are, more, in"
48084,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.090909091,"show, that, a"
48085,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.090909091,"the, at, with, of, and"
48086,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.090909091,"the, of, and, at, a"
48087,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.090909091,"the, in, a, of, with, is, and, market"
48088,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.090909091,"the, a, from, market"
48089,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.090909091,"a, was, the, of, he"
48090,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.090909091,"the, virus, of, from"
48091,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.090909091,"the, virus, a, of"
48092,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.090909091,"the, and, outbreaks, in"
48093,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.090909091,"and, the, of, from, in"
48094,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.090909091,"been, and, in, the, of"
48095,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.090909091,"the, other, of, in, and, coronavirus"
48096,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.090909091,"to, other, than, the, in"
48097,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.090909091,"animal, in, the, to"
48098,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.090909091,"the, more, to, than"
48099,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.090909091,"than, sars-cov-2, in"
48100,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.090909091,"at, the, was, in"
48101,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.090909091,"at, sars-cov-2, in, and"
48102,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.090909091,"the, that, in, market"
48103,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.090909091,"the, diversity, sars-cov-2"
48104,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.090909091,"the, and, huanan, market"
48105,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.090909091,"sars-cov-2, likely, in, the"
48106,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.090909091,"a, animal, and"
48107,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.090909091,"and, an, animal"
48108,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.090909091,"to, of, and, into, from"
48109,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.090909091,"sars-cov-2, at, in, and"
48110,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.090909091,"and, from, to, in"
48111,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.090909091,"to, humans, of, and, in"
48112,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.090909091,"the, as, of, and, zoonotic"
48113,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.090909091,"the, in, of, as, and"
48114,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.090909091,"in, march, a, of, to, the, as"
48115,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.090909091,"and, a, to, the, of, as"
48116,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.090909091,"the, of, and, a, in, as, to"
48117,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.090909091,"the, as, a, of, to, and"
48118,"The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.090909091,"that, with, zoonotic"
48119,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.090909091,"from, that, sars-cov-2, a"
48120,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.090909091,"sars-cov-2, in, a, that, the"
48121,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.090909091,"the, of, three"
48122,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.090909091,"that, was, and, were"
48123,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.090909091,"that, the, of, covid-19, to"
48124,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.090909091,"the, that, more, than"
48125,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.090909091,"that, the, and, than"
48126,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.090909091,"the, to, of, than"
48127,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.090909091,"a, of, the, in, 2020,, sars-cov-2"
48128,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.090909091,"in, animals,, animals, and, from"
48129,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.090909091,"in, the, of, sars-cov-2, and, a"
48130,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.090909091,"the, sars-cov-2, in, and, including"
48131,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.090909091,"in, a, and, both, sars-cov-2, the"
48132,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.090909091,"the, of, and, both, in"
48133,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.090909091,"sars-cov-2, from, a, in, an"
48134,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor",0.090909091,"to, possible, a"
48135,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.090909091,"a, of, that, the, from, in"
48136,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.090909091,"a, of, the, in, to, sars-cov-2"
48137,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.090909091,"that, the, sars-, cov-2, only"
48138,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.090909091,"that, sars-cov-2, a, the, of, from"
48139,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.090909091,"a, to, in, may, sars-cov-2, the"
48140,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.090909091,"one, from, a, sars-cov-2, to, in, the"
48141,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.090909091,"a, that, the, it, had, been, out, by"
48142,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.090909091,"from, an, in, to, and"
48143,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.090909091,"to, any, and, was, sars-cov-2"
48144,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.090909091,"it, is, that, sars-cov-2, if, from"
48145,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.090909091,"in, viruses, are, and, sars-cov-2, that, is"
48146,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.090909091,"the, virus, to, and, had, in"
48147,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.090909091,"as, the, to, be, at, of, for, and"
48148,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.090909091,"the, are, to, in, for, of, as, viruses, virus, and, other"
48149,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.090909091,"a, is, in, that, their"
48150,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.090909091,"a, that, had"
48151,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.090909091,"their, that, a"
48152,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.090909091,"that, or, sars-cov-2"
48153,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.090909091,"a, in, sars-cov-2"
48154,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","No SARS2 at 

WIV, no lab leak.”",0.090909091,"no, at"
48155,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.090909091,"the, entire, of, coronavirus, is, more, than, to, can"
48156,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.090909091,"coronavirus, in, the, that, was, to, of, at"
48157,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.090909091,"that, were, the, animals"
48158,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.090909091,"on, the, that, sars-cov-2, by"
48159,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.090909091,"that, the, infected, animals, at"
48160,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.090909091,"there, that, sars-cov-2, be, by"
48161,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.090909091,"the, with, that, at"
48162,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.090909091,"were, sars-cov-2, with, the"
48163,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.090909091,"the, by, at, on, with"
48164,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.090909091,"at, with, sars-cov-2, the, on"
48165,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.090909091,"the, sars-cov-2, with, by"
48166,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.090909091,"a, as, the, in, that, to"
48167,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.090909091,"the, market, that, humans, in"
48168,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.090909091,"in, animals, to, the, genetic"
48169,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.090909091,"the, to, a, that, evidence"
48170,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.090909091,"that, the, genome, a"
48171,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.090909091,"that, it, to, the"
48172,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.090909091,"from, as, that, virus, to, for, the"
48173,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.090909091,"the, in, march, a, as, to, of"
48174,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.090909091,"analysis, of, the, covid-19, virus, from, in"
48175,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.090909091,"analysis, of, the, that, is, same"
48176,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.090909091,"the, and, not, but, in, were"
48177,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.090909091,"on, in, the, of, and, found, most, at"
48178,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.090909091,"and, in, our, the, of, is, reviewed"
48179,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.090909091,"it, is, that, the, most, a"
48180,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.090909091,"that, evidence, a, to"
48181,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.090909091,"to, a, from, in"
48182,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.090909091,"that, about, a, of, sars-cov-2"
48183,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.090909091,"a, that, the, was, scientists"
48184,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.090909091,"he, of, a, the, was"
48185,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.090909091,"of, evidence, that, the, is, a"
48186,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.090909091,"that, the, of, evidence, a, was, to"
48187,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.090909091,"the, of, that, no, evidence, to"
48188,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.090909091,"have, that, the, for, of"
48189,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.090909091,"from, as, and, camels,"
48190,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.090909091,"to, and, with, the"
48191,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.090909091,"on, the, a, coronavirus, that"
48192,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.090909091,"to, that, the, and, as"
48193,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.090909091,"virus, the, and, that"
48194,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.090909091,"the, animals, that, were"
48195,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.090909091,"the, is, also, and"
48196,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.090909091,"the, this, that, animals"
48197,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.090909091,"and, that, the"
48198,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.090909091,"this, that, the, virus"
48199,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.090909091,"and, to, coronaviruses, a"
48200,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.090909091,"that, and, of, species"
48201,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.090909091,"that, a, of, and, to"
48202,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.090909091,"to, that, of, and"
48203,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.090909091,"to, a, that, and"
48204,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.090909091,"have, that, to"
48205,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.090909091,"a, of, species, and, that"
48206,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.090909091,"and, to, that, have, infect"
48207,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.090909091,"of, zoonotic, to, a"
48208,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.090909091,"all, that, to"
48209,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.090909091,"of, that, to, a"
48210,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.090909091,"in, that, from, animals, and"
48211,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.090909091,"in, animals,, from, and, animals"
48212,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.090909091,"from, and, their, can"
48213,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.090909091,"other, that, and, from"
48214,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.090909091,"from, that, in"
48215,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.090909091,"that, in, and, from"
48216,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.090909091,"in, which, their"
48217,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.090909091,"considered, the, in"
48218,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.090909091,"of, and, in, the"
48219,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.090909091,"coronavirus, is, to, human"
48220,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.090909091,"coronavirus, is, to"
48221,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.090909091,"coronavirus, and, human"
48222,"In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.090909091,"to, human, beings"
48223,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.090909091,"through, to, human"
48224,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.090909091,"to, through, and, human"
48225,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.090909091,"sequence, bat, that, the, and"
48226,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.090909091,"studies, that, the, and, a"
48227,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.090909091,"bat, coronavirus, to"
48228,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.090909091,"as, host, of"
48229,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.090909091,"the, of, as, host"
48230,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.090909091,"of, with, a, the, in"
48231,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.090909091,"the, in, bats, possible"
48232,"the close relation  

between SARS coronavirus and 2019-nCoV","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.090909091,"the, close, and"
48233,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.090909091,"in, the, of, and, with, huanan"
48234,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.090909091,"of, the, that, group"
48235,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.090909091,"been, in, to, the, of"
48236,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.090909091,"to, the, that, been, this"
48237,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.090909091,"the, of, in, that, this, than"
48238,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.090909091,"the, this, or, of"
48239,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.090909091,"in, market, wuhan, december"
48240,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.090909091,"of, cases, the, huanan"
48241,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.090909091,"in, the, of, to, and, this"
48242,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.090909091,"the, relationship, of, and, to"
48243,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.090909091,"of, that, the, is, from"
48244,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.090909091,"be, that, a, sars-cov-2"
48245,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.090909091,"the, sars-cov-2, from, intermediate"
48246,"According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.090909091,"according, to, is"
48247,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.090909091,"the, a, to, that, bats, as, intermediate, and, virus"
48248,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.090909091,"from, the, was, to, a, virus, that, as, and"
48249,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.090909091,"the, a, as, and"
48250,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.090909091,"the, of, has, for"
48251,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.090909091,"that, and, for, to, the, with"
48252,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.090909091,"the, of, a, to, bat, with, genome, and, that, from, horseshoe"
48253,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.090909091,"the, that, virus, with, which"
48254,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Bats have been reported as being the rich source of 

coronaviruses",0.090909091,"of, the, been, have"
48255,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","Bats have been reported as being the rich source of 

coronaviruses",0.090909091,"have, bats"
48256,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.090909091,"have, the, to, a"
48257,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.090909091,"have, the, sars-cov-2, with"
48258,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.090909091,"of, and, the, from, pangolins"
48259,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.090909091,"their, can, and, from"
48260,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.090909091,"sars-cov-2, spike, and"
48261,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.090909091,"the, and, from, similar, to"
48262,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.090909091,"to, the, protein, can"
48263,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.090909091,"with, sars-cov-2, the, bat"
48264,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.090909091,"about, sars-cov-2, ratg13, the"
48265,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.090909091,"sars-cov-2, with, bat, ratg13, the"
48266,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.090909091,"the, and, available"
48267,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.090909091,"the, of, intermediate, to"
48268,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.090909091,"is, the, bat, pangolin"
48269,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.090909091,"of, and, bat"
48270,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.090909091,"be, of, the, and, to"
48271,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.090909091,"to, humans, the, is"
48272,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.090909091,"sars-cov-2, is, and, to, which, that"
48273,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.090909091,"of, that, animal, by, the, suggesting, to"
48274,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.090909091,"bats, and, are, the"
48275,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.090909091,"and, from, the, was"
48276,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.090909091,"from, in, and, to"
48277,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.090909091,"the, virus, and, was"
48278,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.090909091,"the, are, to, a"
48279,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.090909091,"the, a, virus, in"
48280,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.090909091,"and, from, the, virus, humans"
48281,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.090909091,"to, a, virus, have, that, in, and, the"
48282,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.090909091,"the, animals, that, infected, at"
48283,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.090909091,"the, to, through, humans, and"
48284,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.090909091,"that, a, the, virus, humans, in, at, have, to"
48285,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.090909091,"the, have, in, from, and"
48286,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.090909091,"to, that, the, virus, bats"
48287,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.090909091,"the, to, that, may, through"
48288,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.090909091,"zoonotic, the, that, to"
48289,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.090909091,"the, what, to, of"
48290,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.090909091,"and, they, the, was, of"
48291,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.090909091,"genetic, the, in, to, animals"
48292,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.090909091,"has, in, the, and, are, to"
48293,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.090909091,"in, the, of, was, virus, to, and"
48294,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.090909091,"are, to, originated, in"
48295,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.090909091,"been, to, genetic, in"
48296,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.090909091,"that, to"
48297,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.090909091,"genetic, in, that"
48298,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.090909091,"used, has, that, in"
48299,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.090909091,"in, show, that"
48300,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.090909091,"the, a, is"
48301,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.090909091,"that, of, is, a, the"
48302,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.090909091,"the, of, a, virus, at, was"
48303,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.090909091,"that, and, dents, the"
48304,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.090909091,"the, natural, in"
48305,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.090909091,"that, in, humans"
48306,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.090909091,"to, likely, in, the"
48307,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.090909091,"that, likely, to"
48308,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.090909091,"the, natural, and, to"
48309,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.090909091,"in, the, and, to, virus, had"
48310,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.090909091,"had, to, and, the, in"
48311,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.090909091,"is, and, to, in"
48312,The COVID-19 most likely developed from bat origin coronaviruses,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.090909091,"the, origin"
48313,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.090909091,"is, the, in, its"
48314,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.090909091,"similar, and, sars-cov"
48315,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.090909091,"that, the, to, in, origin, and"
48316,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.090909091,"also, the, and, with, into"
48317,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.090909091,"the, with, and, into"
48318,"According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.090909091,"sars-like, bat"
48319,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.090909091,"that, and, is"
48320,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.090909091,"the, and, to, that, of"
48321,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.090909091,"the, intermediate, host, to"
48322,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.090909091,"the, positive, for, civet, palm"
48323,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.090909091,"and, the, identity, of, bat"
48324,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.090909091,"the, for, a, wild, is"
48325,"Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.090909091,"the, reservoir"
48326,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.090909091,"host, bats, the"
48327,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.090909091,"the, of, bats, are"
48328,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.090909091,"the, of, bats, are, natural"
48329,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.090909091,"the, be, contact"
48330,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.090909091,"and, outbreaks, in, the"
48331,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.090909091,"the, and, in, not, were, but"
48332,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.090909091,"the, only, in, were, and, but, not"
48333,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.090909091,"in, the, and, reported"
48334,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.090909091,"the, and, but"
48335,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.090909091,"is, the, to, that"
48336,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.090909091,"the, that, bat, to"
48337,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.090909091,"the, genomic, to, that"
48338,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.090909091,"wuhan, the, in, however,"
48339,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.090909091,"the, in, it, virus, that, not"
48340,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.090909091,"that, the, in, market"
48341,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.090909091,"it, that, the"
48342,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.090909091,"the, seafood, it, that, was, in"
48343,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.090909091,"it, was, not, the, that, in"
48344,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.090909091,"in, wuhan, the, virus"
48345,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.090909091,"in, the, that, virus"
48346,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.090909091,"may, a, that, in"
48347,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.090909091,"infected, with, the, of"
48348,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.090909091,"a, of, the, that, or, have"
48349,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.090909091,"that, the, of, may, have, as"
48350,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.090909091,"be, the, hosts"
48351,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.090909091,"the, that, from, at, for"
48352,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.090909091,"for, the, palm, civet, positive"
48353,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.090909091,"that, the, from, market"
48354,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.090909091,"viruses, a, but, of"
48355,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.090909091,"novel, with, bat, that, the, of"
48356,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.090909091,"the, a, of, group, researchers, viruses, with, that, bats"
48357,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.090909091,"with, the, of, that, could"
48358,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.090909091,"to, the, sars-cov-2, has"
48359,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.090909091,"the, sars-cov, and, that, a, to"
48360,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.090909091,"a, the, and, by, to, it, for, that, study,, same, host"
48361,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.090909091,"the, that, a, receptor, and, to"
48362,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.090909091,"the, a, which, to, and, sars-cov, was"
48363,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.090909091,"the, host, sars-cov-2, and"
48364,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.090909091,"genome, the, to, bat, human"
48365,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.090909091,"the, to, more, coronavirus, is, than, entire, of, can"
48366,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.090909091,"human, can, to, used"
48367,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.090909091,"to, for, the, is"
48368,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.090909091,"is, bat, can, be, to, coronavirus"
48369,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.090909091,"the, is, previously, used"
48370,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.090909091,"be, the, animal, human, for"
48371,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.090909091,"as, the, of, and, at, to, for, be"
48372,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.090909091,"be, the, recombination, and, of"
48373,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.090909091,"sars-cov, to, bat"
48374,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.090909091,"bat, sars-like"
48375,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.090909091,"to, human, used, can"
48376,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.090909091,"all, humans, to"
48377,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.090909091,"humans, and, to, intermediate"
48378,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.090909091,"cause, in, and"
48379,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.090909091,"to, hosts, intermediate"
48380,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.090909091,"to, in, and, human"
48381,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.090909091,"the, bat, and, that, sequence"
48382,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.090909091,"of, the, novel, with, bat, that"
48383,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.090909091,"sars-cov-2, of, the, and, with, genetic, analysis"
48384,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.090909091,"that, the, it"
48385,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.090909091,"of, are, human, coronaviruses"
48386,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.090909091,"the, coronaviruses, that, of"
48387,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.090909091,"been, the, of, has"
48388,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.090909091,"the, of, have, to, and, virus, identical"
48389,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.090909091,"several, of, have, and, the, to"
48390,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.090909091,"may, to, that"
48391,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.090909091,"sars-cov-2, spike, to, that"
48392,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.090909091,"that, sars-cov-2, studies"
48393,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.090909091,"in, a, of, the, as"
48394,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.090909091,"in, the, of, as, a, from"
48395,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.090909091,"are, a, in, the"
48396,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.090909091,"in, the, same, pangolin"
48397,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.090909091,"have, likely, genetic, and, bat"
48398,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.090909091,"that, of, bat, recombination, genetic"
48399,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.090909091,"is, that, of, and, collected"
48400,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.090909091,"and, of, that, by"
48401,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.090909091,"of, that, bat, and"
48402,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.090909091,"that, is, of"
48403,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.090909091,"that, and, on, of"
48404,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.090909091,"the, in, virus"
48405,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.090909091,"in, the, virus, has"
48406,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.090909091,"the, in, bats, most"
48407,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.090909091,"the, has, virus"
48408,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",Many of these CoVs can infect several animal species as well,0.090909091,"of, animal"
48409,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",Many of these CoVs can infect several animal species as well,0.090909091,"species, as, of"
48410,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.090909091,"to, a, human"
48411,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.090909091,"to, from, a"
48412,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.090909091,"the, is, to, humans"
48413,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.090909091,"the, is, to, for"
48414,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.090909091,"is, humans, it, to"
48415,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.090909091,"virus, from, is, the"
48416,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.090909091,"the, to, bat, sars-cov-2"
48417,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.090909091,"all, to, humans"
48418,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.090909091,"the, sars-cov-2, to, humans"
48419,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.090909091,"coronaviruses, bats, are, to, sars-cov-2"
48420,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.090909091,"to, sars-cov-2, the, bats"
48421,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.090909091,"the, also, of, coronaviruses"
48422,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.090909091,"the, isolated, in, of"
48423,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.090909091,"the, cause, in"
48424,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.090909091,"coronaviruses, to, the"
48425,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.090909091,"the, of, bats, from"
48426,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.090909091,"the, from, to, of"
48427,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.090909091,"genetic, their, that"
48428,The COVID-19 most likely developed from bat origin coronaviruses,hese close genetic relations suggest that they all have their ecological origin in bat populations,0.090909091,"bat, origin"
48429,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.090909091,"are, in, the, and"
48430,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.090909091,"may, the, and"
48431,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.090909091,"in, the, from, to, and"
48432,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.090909091,"an, to, from, and, in"
48433,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.090909091,"human, infected, the"
48434,"This suggests that the BANAL series may be able to directly infect  

humans.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.090909091,"the, may, to"
48435,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.090909091,"to, in, and, from"
48436,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.090909091,"the, and, been, from"
48437,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.090909091,"to, the, and, may, have"
48438,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.090909091,"a, and, animal"
48439,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.090909091,"is, that, and"
48440,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.090909091,"suggests, that, is, a, sars-cov-2"
48441,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.090909091,"that, a, animal, evidence"
48442,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.090909091,"a, natural, origin"
48443,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.090909091,"and, has, a, that, not"
48444,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.090909091,"bats, in"
48445,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.090909091,"bats, sars-"
48446,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.090909091,"and, species, the"
48447,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.090909091,"from, is, sars-cov-2, the"
48448,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.090909091,"from, animal, the"
48449,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.090909091,"that, be, sars-cov-2, by, there"
48450,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.090909091,"to, humans, and, intermediate"
48451,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.090909091,"to, humans, it, is"
48452,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.090909091,"to, it, that, contact, of"
48453,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.090909091,"more, to, that, of, sars-cov-2, and"
48454,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.090909091,"to, that, sars-cov-2, be, of"
48455,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.090909091,"that, of, to, an, intermediate"
48456,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.090909091,"to, the, coronavirus"
48457,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.090909091,"that, of, to, coronavirus, the"
48458,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.090909091,"that, coronavirus, to"
48459,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.090909091,"the, that, virus, coronavirus"
48460,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.090909091,"of, and, virus, with, coronavirus"
48461,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.090909091,"with, genome, bat, the"
48462,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.090909091,"coronavirus, the, of, virus, and, with"
48463,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.090909091,"the, virus, was, other"
48464,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.090909091,"and, the, virus, was"
48465,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.090909091,"the, was, virus, with, bat, and, of, coronavirus, closest"
48466,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.090909091,"of, covid-19, human, ace2, virus, in, and, the"
48467,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.090909091,"the, of, in, isolated"
48468,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.090909091,"this, the, virus, was, human, with, of, in, isolated"
48469,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.090909091,"of, the, isolated, in, and"
48470,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.090909091,"in, of, the, virus, covid-19, analysis, from"
48471,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.090909091,"the, of, and, virus, from, in, with"
48472,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.090909091,"the, of, and, in, between, 2019"
48473,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.090909091,"the, genome, analyses, of, to"
48474,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.090909091,"the, covid-19, of"
48475,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.090909091,"of, the, to, from, reservoir"
48476,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.090909091,"of, genome, with"
48477,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.090909091,"the, and, many"
48478,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.090909091,"the, to, coronaviruses"
48479,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.090909091,"viruses, to, the, and, that"
48480,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.090909091,"coronaviruses, are, to, that, and"
48481,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.090909091,"and, which, of, in, human, coronaviruses"
48482,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.090909091,"of, infections, are, and"
48483,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.090909091,"of, human, coronaviruses, are"
48484,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.090909091,"in, are, with, bats,"
48485,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.090909091,"a, and, sars-cov, with, the, of"
48486,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.090909091,"the, of, and, to, sars-"
48487,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.090909091,"bats, the, as, to, a"
48488,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.090909091,"the, of, and, novel, coronavirus, natural, a"
48489,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.090909091,"the, and, or, pangolin, of"
48490,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.090909091,"natural, pangolin, and, the, of"
48491,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.090909091,"coronaviruses, to, that, of, sars-cov-2"
48492,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.090909091,"the, has, with, of"
48493,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.090909091,"has, identity, and"
48494,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.090909091,"that, was, and, wuhan, city,"
48495,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.090909091,"the, novel, that, to, and"
48496,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.090909091,"the, of, bat, and, identity"
48497,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.090909091,"the, revealed, that, and"
48498,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.090909091,"virus, that, bat"
48499,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.090909091,"the, and, to, that, of, bat"
48500,"In the 

case of MERS, dromedaries were the principal host.","no modifications were  

recorded for nonstructural proteins NSP7, NSP13  

and the structured and accessory proteins p6 and 8b.",0.090909091,"the, were"
48501,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.090909091,"in, with, identity"
48502,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.090909091,"a, and, that, the, from"
48503,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.090909091,"that, other, and, from"
48504,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.090909091,"and, revealed, that, the"
48505,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.090909091,"a, other, sars-cov-2, the, and"
48506,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.090909091,"from, a, and, sars-cov-2, other, the"
48507,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.090909091,"or, in, to"
48508,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.090909091,"in, sars-cov-2, to, zoonotic"
48509,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.090909091,"sars-, cov-2, only, the, that"
48510,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.090909091,"that, is, bat"
48511,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.090909091,"genomic, that, the, and"
48512,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.090909091,"that, sars-, cov-2, the, and"
48513,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.090909091,"the, of, two, and"
48514,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.090909091,"the, covid-19, of, virus"
48515,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.090909091,"the, covid-19, and, of"
48516,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.090909091,"the, of, type, virus"
48517,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.090909091,"that, from, a, the, in"
48518,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.090909091,"the, from, market, that"
48519,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.090909091,"in, a, and, to, the"
48520,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.090909091,"the, and, a, to, that, in, selling, live, market"
48521,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","the close relation  

between SARS coronavirus and 2019-nCoV",0.090909091,"coronavirus, the"
48522,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","the close relation  

between SARS coronavirus and 2019-nCoV",0.090909091,"and, the, between"
48523,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.090909091,"a, identified, and, in, china"
48524,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.090909091,"were, and, that, was"
48525,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.090909091,"in, december, market, wuhan"
48526,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.090909091,"that, wuhan, city,, was, and"
48527,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.090909091,"on, in, and, that, were, market"
48528,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.090909091,"in, and, that, a"
48529,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.090909091,"that, and, a, on"
48530,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.090909091,"genomic, that, to, the"
48531,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.090909091,"the, that, within, of"
48532,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.090909091,"that, the, 1ab, of"
48533,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.090909091,"to, that, the, of, are"
48534,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.090909091,"the, sars-cov, in, and"
48535,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.090909091,"sars-cov, and, a, the, of, with"
48536,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.090909091,"bat, a, from, in, the, virus, china, of, and"
48537,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.090909091,"and, the, of, sars-cov-2, in, from, a"
48538,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.090909091,"sars-cov-2, a, virus, with, the"
48539,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.090909091,"sars-cov-2, has, and, with"
48540,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.090909091,"in, the, of, sars-cov-2, virus"
48541,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.090909091,"a, that, from, in"
48542,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.090909091,"a, in, is, sars-cov-2"
48543,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.090909091,"in, that, a"
48544,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.090909091,"that, in, from"
48545,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.090909091,"that, in, may, a"
48546,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.090909091,"that, virus, bat"
48547,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.090909091,"that, bat, is"
48548,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.090909091,"may, a, bat"
48549,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.090909091,"from, a, sars-cov-2"
48550,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.090909091,"bat, is, that"
48551,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.090909091,"in, may, bat, species."
48552,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.090909091,"a, from, is"
48553,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.090909091,"a, sars-cov-2, in, is"
48554,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.090909091,"that, sars-cov-2, virus"
48555,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.090909091,"that, from, a, the, sequence, in"
48556,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.090909091,"that, the, sequence, of, a"
48557,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.090909091,"a, the, that, in, sequence"
48558,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.090909091,"in, the, of, for, that, a"
48559,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.090909091,"a, of, the, that, were, identified, these"
48560,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.090909091,"that, from, a, in, intermediate"
48561,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.090909091,"the, a, of, presence, together, with, that, and"
48562,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.090909091,"a, that, the, and, to, sars-cov"
48563,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.090909091,"analyses, genome, to, the, of"
48564,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.090909091,"that, of, to, a, in, sequences, the"
48565,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.090909091,"of, bat, overall, genome, ratg13"
48566,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.090909091,"a, genome, in, that, the, to, of"
48567,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.090909091,"sars-cov-2, and"
48568,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.090909091,"and, the, sars-cov-2"
48569,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.090909091,"and, sars-cov-2, other, hosts, the"
48570,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.090909091,"and, of, sars-cov-2, the"
48571,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.090909091,"to, intermediate, hosts"
48572,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.090909091,"the, of, pangolins"
48573,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.090909091,"bats, the, be, of, are, to, may"
48574,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.090909091,"the, of, that, sars-cov-2, which"
48575,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.090909091,"the, from, huanan, seafood, of"
48576,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.090909091,"he, from, sars-cov-2, the, of"
48577,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.090909091,"bats, and, species, to, be"
48578,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.090909091,"and, that, sars-cov-2, is, which, to"
48579,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.090909091,"coronavirus, is, to, bat, can, be"
48580,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.090909091,"a, coronavirus, in, that, to"
48581,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.090909091,"bat, and, species, to, in"
48582,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.090909091,"and, bat, a, between, species, in"
48583,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.090909091,"is, bat, from, species, in"
48584,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.090909091,"to, and, is, that, in, bat"
48585,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.090909091,"the, sars-cov, and, sars-cov-2, of"
48586,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.090909091,"a, and, of, at, the"
48587,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.090909091,"the, of, et, which, that, as"
48588,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.090909091,"a, of, and, which, the"
48589,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.090909091,"the, acid, of, that, receptor"
48590,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.090909091,"sequences, of, sars-cov-2, and, sars-cov"
48591,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.090909091,"of, sars-cov-2, ace2, which, the"
48592,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.090909091,"sars-cov-2, and, similarity, the, of"
48593,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.090909091,"to, the, of, evidence, no, that"
48594,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.090909091,"the, to, of, intermediate"
48595,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.090909091,"that, the, of, which, as, et"
48596,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.090909091,"the, to, was, of, et"
48597,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.090909091,"the, to, that, was, but"
48598,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.090909091,"the, is, most, to"
48599,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.090909091,"pangolin, intermediate, to, be, the"
48600,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.090909091,"sars-cov-2, a, from, the"
48601,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.090909091,"the, which, sars-cov-2"
48602,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.090909091,"sars-cov-2, the, with, which"
48603,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.090909091,"the, sars-cov-2, a, has"
48604,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.090909091,"the, of, and, hypothesis, that"
48605,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.090909091,"of, that, the, is, a"
48606,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.090909091,"the, that, was, to, coronavirus, in, of, at"
48607,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.090909091,"the, that, with, at"
48608,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.090909091,"a, to, that, coronavirus, in"
48609,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.090909091,"at, the, with, that"
48610,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.090909091,"to, are, and, coronaviruses"
48611,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.090909091,"of, a, the"
48612,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.090909091,"a, that, of"
48613,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.090909091,"the, a, of, that"
48614,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.090909091,"a, the, be"
48615,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.090909091,"the, of, a, that"
48616,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.090909091,"the, infected, with, of"
48617,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.090909091,"the, human, infected"
48618,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.090909091,"with, are, sars-cov-2, the"
48619,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.090909091,"are, with, sars-cov-2, the"
48620,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.090909091,"with, the, sars-cov-2"
48621,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.090909091,"of, sars-cov-2, the, human"
48622,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.090909091,"at, the, of, and, in, on, found, most"
48623,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.090909091,"the, of, in, with, and, huanan"
48624,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.090909091,"in, the, of, patients, and"
48625,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.090909091,"reported, that, the, to"
48626,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.090909091,"the, that, of, linked, to, huanan"
48627,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.090909091,"in, the, considered"
48628,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.090909091,"to, the, have, in, covid-19"
48629,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.090909091,"the, to, have, in"
48630,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.090909091,"the, have, in, is"
48631,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.090909091,"bats, the, of, to, and, et, 2020)"
48632,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.090909091,"cov, the, sars-cov-2, bats"
48633,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.090909091,"identified, bat, the"
48634,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.090909091,"bat, in, identified"
48635,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.090909091,"sars-cov-2, in, rhinolophus, bats, been"
48636,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.090909091,"since, sars-cov-2, in, related"
48637,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.090909091,"have, been, in, sars-cov-2"
48638,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.090909091,"animal, the, of"
48639,"atural  

selection in an animal host before zoonotic  

transfer;","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.090909091,"an, animal"
48640,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.090909091,"and, spike, sars-cov-2"
48641,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.090909091,"sars-cov-2, a"
48642,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.090909091,"pangolin, and, a"
48643,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.090909091,"pangolin, sars-cov-2, spike, ace2"
48644,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.090909091,"the, within, that, of"
48645,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.090909091,"a, and, pangolin"
48646,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.090909091,"that, a, even, the, of"
48647,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.090909091,"even, of, and, the, in"
48648,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.090909091,"viruses, in, the"
48649,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.090909091,"the, for, has, of"
48650,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.090909091,"in, of, the, has"
48651,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.090909091,"in, has, the"
48652,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.090909091,"sars-cov-2, from, the"
48653,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.090909091,"natural, of, and, a, as"
48654,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.090909091,"the, in, sars-cov-2, sequence, sites"
48655,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.090909091,"the, of, indicated, that, in, to"
48656,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.090909091,"the, of, which, to, in, virus, was"
48657,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.090909091,"that, sars-cov-2, the, ratg13"
48658,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","this one jumped from bats origin  

into humans",0.090909091,"humans, from"
48659,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","this one jumped from bats origin  

into humans",0.090909091,"origin, one"
48660,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.090909091,"the, a, to, laboratory"
48661,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.090909091,"the, human, to, a"
48662,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.090909091,"the, to, by"
48663,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.090909091,"human, are, in, all"
48664,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.090909091,"human, virus, most"
48665,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.090909091,"as, and, to, the, of, have, a"
48666,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.090909091,"the, a, coronaviruses, are, health"
48667,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.090909091,"coronaviruses, found, bats, china"
48668,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.090909091,"bats, found, by, the"
48669,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.090909091,"by, bats, the"
48670,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K",0.090909091,"several, to, in"
48671,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.090909091,"in, the, has, and"
48672,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.090909091,"of, and, a, zoonotic, in"
48673,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.090909091,"related, that, are, to"
48674,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.090909091,"also, to, are, related, bats, that, this, for"
48675,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.090909091,"the, host, of, as"
48676,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.090909091,"as, and, the, of, it, natural"
48677,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.090909091,"the, of, it, for, and"
48678,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.090909091,"from, sars-cov-, the, of"
48679,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.090909091,"two, of, the, from, and"
48680,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.090909091,"the, with, and, for"
48681,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.090909091,"with, the, of, as, host"
48682,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.090909091,"a, to, similarity"
48683,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.090909091,"to, sars-cov-2, or"
48684,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.090909091,"to, genome, sars-cov-2"
48685,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.090909091,"to, sars-cov-2, has, a"
48686,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.090909091,"sars-cov-2, a, or, genome"
48687,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.090909091,"a, to, sars-cov-2, genome"
48688,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.090909091,"a, similarity, sars-cov-2, to"
48689,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.090909091,"the, with, sars-cov-2, were"
48690,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.090909091,"the, it, in, with"
48691,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.090909091,"the, sars-cov-2, in, pangolins"
48692,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.090909091,"with, the, intermediate, host"
48693,"Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.090909091,"to, a, possible"
48694,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.090909091,"a, bat, of, the"
48695,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.090909091,"to, the, of, may, as"
48696,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.090909091,"of, the, that, or, to"
48697,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.090909091,"that, to, sars-cov-2, no"
48698,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.090909091,"the, to, that, sars-cov-2, is, of"
48699,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.090909091,"to, that, the, of, is, sars-cov-2"
48700,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.090909091,"was, sars-cov-2, to, and, any"
48701,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.090909091,"the, virus, to, by"
48702,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.090909091,"and, was, by, the"
48703,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.090909091,"the, been, by, to, virus"
48704,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.090909091,"sars-cov-2, by, genome, the"
48705,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.090909091,"the, sars-cov-2, and, been"
48706,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.090909091,"to, the, by, virus"
48707,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.090909091,"the, to, related, that, into, in, is"
48708,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.090909091,"is, not, the, in"
48709,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.090909091,"the, indicate, that"
48710,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.090909091,"to, the, in, that"
48711,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.090909091,"the, of, and, in, this, to"
48712,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.090909091,"the, of, to, that, humans, sars-cov-2"
48713,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.090909091,"suggests, that, sars-cov-2, a, is"
48714,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.090909091,"the, of, that, sequences, a, in, to"
48715,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.090909091,"the, that, a, found, in, coronavirus"
48716,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.090909091,"the, of, study, that, in, a, to"
48717,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.090909091,"a, of, sars-, cov-2, analysis"
48718,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.090909091,"in, found, of, pangolin, sequences, to"
48719,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.090909091,"sars-cov-2, with, genome, the"
48720,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.090909091,"and, the, from, in"
48721,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.090909091,"in, of, the, which, and"
48722,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.090909091,"the, of, coronaviruses, which"
48723,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.090909091,"the, from, which, and"
48724,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.090909091,"sars-cov-2, a, with"
48725,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.090909091,"in, a, of, virus, that, found"
48726,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.090909091,"a, of, in, found, virus, that"
48727,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.090909091,"of, in, that, virus"
48728,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.090909091,"has, a, of, that, bat"
48729,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.090909091,"research, found, sars-cov-2, of"
48730,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.090909091,"to, that"
48731,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.090909091,"the, similar, to, that"
48732,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.090909091,"shares, with, virus"
48733,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.090909091,"to, the, from"
48734,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.090909091,"identity, to, the"
48735,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.090909091,"that, a, the, of, is"
48736,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.090909091,"a, of, animal, that, the"
48737,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.090909091,"has, been, that, a"
48738,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.090909091,"the, is, not, of"
48739,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.090909091,"of, the, that, analysis, is, same"
48740,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.090909091,"group, of, the, that"
48741,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.090909091,"the, region, found, in"
48742,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.090909091,"the, sars-cov-2, has, to"
48743,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.090909091,"the, and, has, in"
48744,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.090909091,"as, and, the, to, et, sars-cov-2"
48745,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.090909091,"the, sars-cov-2, to, also, and"
48746,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.090909091,"also, from, in, the"
48747,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.090909091,"the, sars-cov-2, in, from, and"
48748,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.090909091,"to, sars-cov-2, has, bat-, the"
48749,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.090909091,"also, the, to, as, an"
48750,"Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution","bats are also important reservoir species for a great 

range of coronaviruses",0.090909091,"a, for"
48751,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","bats are also important reservoir species for a great 

range of coronaviruses",0.090909091,"of, bats, for"
48752,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","bats are also important reservoir species for a great 

range of coronaviruses",0.090909091,"a, are, of"
48753,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","bats are also important reservoir species for a great 

range of coronaviruses",0.090909091,"species, of, bats"
48754,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.090909091,"the, of, from, to, and"
48755,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.090909091,"the, of, species, in, to"
48756,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.090909091,"an, of, humans, and"
48757,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.090909091,"the, in, bats, sars-cov-2"
48758,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.090909091,"of, the, in, to, those"
48759,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.090909091,"2, and, from, the"
48760,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.090909091,"the, show, from"
48761,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.090909091,"two, the, from, and"
48762,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.090909091,"that, of, with"
48763,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.090909091,"he, of, that"
48764,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.090909091,"of, sars-cov-2,, protein, that, than"
48765,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.090909091,"in, the, sequence, sars-cov-2, sites"
48766,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.090909091,"can, be, to, that"
48767,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.090909091,"to, be, coronavirus"
48768,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.090909091,"in, the, from, to, at, and"
48769,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.090909091,"similar, to, from, and, the"
48770,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.090909091,"the, in, bats, and, to"
48771,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.090909091,"from, to, ratg13, and"
48772,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.090909091,"in, the, by, and, to, is, ratg13"
48773,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.090909091,"to, the, rbd, from, by"
48774,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.090909091,"in, the, a, to, for"
48775,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.090909091,"to, can, the, protein"
48776,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.090909091,"the, a, in, to"
48777,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.090909091,"sars-cov-2, pangolin-cov, with"
48778,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.090909091,"the, of, as, natural, it, and"
48779,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.090909091,"et, to, the, sars-cov-2, and, as"
48780,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.090909091,"natural, of, and, to, that, such, as"
48781,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.090909091,"of, and, that, for, with, or"
48782,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.090909091,"with, the, of, and, may, cats"
48783,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.090909091,"a, that, species, of, and"
48784,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.090909091,"transmission, sars-cov-2, between, and, with"
48785,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.090909091,"the, for, sars-cov-2, humans, intermediate"
48786,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.090909091,"in, to, the, than, other"
48787,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.090909091,"the, for, to, with, that, and"
48788,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.090909091,"the, intermediate, for, sars-cov-2"
48789,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.090909091,"the, key, amino, to, than"
48790,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.090909091,"have, that, infect, to, and"
48791,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.090909091,"may, the, through, to, that"
48792,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.090909091,"are, in, to, the, has, and"
48793,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.090909091,"that, it, to, the, and"
48794,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.090909091,"sars-cov-2, to, a, and, in"
48795,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.090909091,"the, that, was, to, and"
48796,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.090909091,"reported, to, the, that"
48797,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.090909091,"the, a, that, in, beta"
48798,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.090909091,"that, study, sars-cov-2, in"
48799,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.090909091,"the, and, also, is"
48800,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.090909091,"through, the, and, to, humans"
48801,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.090909091,"the, of, for, it, and"
48802,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.090909091,"the, by, and, to, of"
48803,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.090909091,"the, is, by, species"
48804,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.090909091,"the, very, to"
48805,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.090909091,"to, the, intermediate, host"
48806,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.090909091,"the, as, intermediate, to"
48807,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.090909091,"an, a, the, from"
48808,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.090909091,"the, from, a"
48809,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.090909091,"very, to, the"
48810,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.090909091,"fully, and, a, that"
48811,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.090909091,"that, the, of, was, to, evidence, a"
48812,"In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.090909091,"in, to, several"
48813,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.090909091,"and, species, in, the"
48814,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.090909091,"the, at, and, to"
48815,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.090909091,"the, species, in"
48816,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.090909091,"in, at, sars-cov-2, the"
48817,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.090909091,"the, of, that, from, was"
48818,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.090909091,"that, the, of, in, genetic"
48819,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.090909091,"this, that, from, in, the, market, at, of"
48820,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.090909091,"genetic, that, of, the"
48821,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.090909091,"that, sequences, the, of"
48822,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.090909091,"of, at, the, in, that"
48823,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.090909091,"to, bat, coronavirus"
48824,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.090909091,"of, the, in, market"
48825,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.090909091,"the, from, that, sars-cov-2"
48826,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.090909091,"that, for, sars-cov-2"
48827,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.090909091,"sars-cov-2, been, in, rhinolophus, bats"
48828,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.090909091,"in, it, that, the, and, sars-cov-2"
48829,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.090909091,"sequences, from, in, the, of, and"
48830,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.090909091,"the, are, of, coronaviruses"
48831,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.090909091,"the, a, highly, that, from, at"
48832,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.090909091,"from, the, of, that, a, sars-cov-2"
48833,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.090909091,"that, if, it, sars-cov-2, from, is"
48834,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.090909091,"the, that, a, even, of"
48835,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.090909091,"sars-cov-2, a, genome, or"
48836,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.090909091,"sars-cov-2, the, that, is, result, of"
48837,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.090909091,"the, of, from, a, virus"
48838,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.090909091,"to, the, of, virus, spillover"
48839,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.090909091,"sars-cov-2, to, the, natural"
48840,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.090909091,"the, of, sars-cov-2, zoonotic"
48841,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.090909091,"of, the, virus, covid-19"
48842,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.090909091,"in, the, are, more"
48843,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.090909091,"viruses, reservoirs, and, to, which, the"
48844,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.090909091,"sars-cov-2, belongs, the"
48845,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.090909091,"of, sars-cov-2, including"
48846,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.090909091,"the, belongs, which"
48847,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.090909091,"the, of, diversity"
48848,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.090909091,"of, and, bats, for"
48849,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.090909091,"of, and, the, for"
48850,Many of these CoVs can infect several animal species as well,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.090909091,"of, species, as"
48851,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.090909091,"to, sars-cov-2, the, bat, and"
48852,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.090909091,"of, and, the, bats, bat"
48853,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.090909091,"malayan, and, sars-cov-2, intermediate, to, the"
48854,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.090909091,"sars-cov-2, bat, to, intermediate"
48855,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.090909091,"that, sars-cov-2, including, and, to"
48856,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.090909091,"the, that, sars-cov-2, and, are, in"
48857,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.090909091,"in, the, including, and, sars-cov-2"
48858,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.090909091,"in, the, southeast"
48859,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.090909091,"and, in, to"
48860,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.090909091,"the, to, and, viruses"
48861,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.090909091,"the, and, in, related"
48862,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.090909091,"the, for, to"
48863,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.090909091,"in, for, were, to"
48864,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.090909091,"the, species, and"
48865,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.090909091,"and, bat, species, to, in"
48866,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.090909091,"an, to, and"
48867,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.090909091,"the, bat, and, suggesting, same"
48868,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.090909091,"a, between, and, bat, species, in"
48869,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.090909091,"the, this, in, of, living"
48870,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.090909091,"viruses, of, the, in, and"
48871,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.090909091,"genetic, that, recombination, of, bat"
48872,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.090909091,"in, species, of, to, the"
48873,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.090909091,"the, of, genetic, in, that"
48874,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.090909091,"the, that, of, covid-19, in, but"
48875,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.090909091,"can, the, of, that, a"
48876,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.090909091,"the, covid-19, to, in"
48877,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.090909091,"genetic, that, a, of, the"
48878,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.090909091,"that, the, bat, viruses, same"
48879,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.090909091,"that, to, a, the, of"
48880,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.090909091,"the, of, infected, that, to, in, is, this"
48881,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.090909091,"bats, also, to, related, that, are, for, this"
48882,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.090909091,"into, the, that, is, in, related, to"
48883,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.090909091,"related, bat, to, as, is, which, similar, the"
48884,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.090909091,"the, that, to, a, cluster, also, bat, and"
48885,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.090909091,"the, genetic, similar, to"
48886,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.090909091,"sars-cov-2, the, genetic, to, closest"
48887,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.090909091,"the, bat, to, similar, as, related, which, is"
48888,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.090909091,"is, which, the, bat, by"
48889,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.090909091,"similar, sars-cov-2, closest, bat"
48890,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.090909091,"sars-cov-2, to, which, the"
48891,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.090909091,"closest, to, the, whole, genome"
48892,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.090909091,"sars-cov-2, with, sars-, and, at, to"
48893,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.090909091,"in, the, and, a, both, sars-cov-2"
48894,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.090909091,"related, to, sars-cov-2, in, and"
48895,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.090909091,"the, are, with, sars-cov-2, both, it"
48896,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.090909091,"to, sars-, the, and, are, sars-cov-2"
48897,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.090909091,"to, the, by, a, with"
48898,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.090909091,"the, sars-cov-2, spike, to, of"
48899,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.090909091,"the, of, closely, related, by, to"
48900,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.090909091,"by, the, are"
48901,"S1/S2 cleavage sites of coronaviruses are frequently modi- 

fied by insertions or deletions (indels) during evolution","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.090909091,"of, are, by"
48902,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.090909091,"the, and, to, of, is"
48903,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.090909091,"and, sars-, to, the, of"
48904,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.090909091,"is, that, to, the"
48905,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.090909091,"by, in, to, the, of, natural, is"
48906,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.090909091,"in, a, of, for, found, to, that"
48907,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.090909091,"to, human, through"
48908,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.090909091,"the, of, to, through"
48909,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.090909091,"that, the, than, human, with, of, have, to"
48910,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.090909091,"to, the, have, of, that"
48911,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.090909091,"the, with, that, than"
48912,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","This suggests that the BANAL series may be able to directly infect  

humans.",0.090909091,"the, to, may"
48913,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","This suggests that the BANAL series may be able to directly infect  

humans.",0.090909091,"that, directly, to"
48914,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.090909091,"to, in, that, human"
48915,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.090909091,"that, viruses, in, human, to"
48916,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.090909091,"the, of, sars-cov-, from"
48917,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.090909091,"in, the, also, from"
48918,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.090909091,"from, the, more"
48919,"Those who eagerly peddle suggestions of 

laboratory involvement have consistently failed to present 

credible arguments to support their positions.","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.090909091,"of, have, their"
48920,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.090909091,"the, of, viruses, spike, a"
48921,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.090909091,"the, and, is, same"
48922,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.090909091,"the, and, cleavage, related, is"
48923,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.090909091,"have, and, to, the, is"
48924,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.090909091,"of, the, three"
48925,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.090909091,"of, sars-cov-2, the, for"
48926,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.090909091,"of, sars-cov-2, and, amino, acid"
48927,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.090909091,"and, to, human, through"
48928,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.090909091,"as, of, the, is, to"
48929,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.090909091,"is, by, the, virus, genetic"
48930,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.090909091,"is, the, to, virus"
48931,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.090909091,"of, virus, by, the"
48932,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.090909091,"to, virus, by, the"
48933,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.090909091,"the, of, virus, is, to"
48934,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.090909091,"was, and, in"
48935,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.090909091,"in, was, t"
48936,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.090909091,"the, virus, is"
48937,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.090909091,"is, sars-cov-2, to, be"
48938,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.090909091,"to, is, related, in"
48939,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.090909091,"a, the, sars-cov-2, genomic, and, are, in"
48940,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.090909091,"in, the, a, sars-cov-2, may, to"
48941,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.090909091,"to, and, with, the, sars-cov-2"
48942,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.090909091,"the, other, sars-cov-2, and, a"
48943,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.090909091,"genomic, the, in, and, to"
48944,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.090909091,"recent, may, to, sars-cov-2, in"
48945,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.090909091,"sars-cov-2, the, with, and, to"
48946,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.090909091,"sars-cov-2, the, covid-19, through"
48947,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.090909091,"sars-cov-2, in, the, and, it, that"
48948,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.090909091,"sars-cov-2, and, in, humans"
48949,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.090909091,"the, first, covid-19, in"
48950,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.090909091,"if, in, will, be"
48951,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.090909091,"and, in, the, sars-cov-2, is"
48952,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.090909091,"in, sars-cov-2, be, infected, that"
48953,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.090909091,"with, that, zoonotic"
48954,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.090909091,"identified, the, of, a, that, these, were"
48955,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.090909091,"the, on, with, at, by"
48956,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.090909091,"of, from, the, huanan, seafood"
48957,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.090909091,"the, of, to, and, by"
48958,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.090909091,"the, was, to, with, of"
48959,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.090909091,"have, that, the, virus, in, to, humans, at, a"
48960,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.090909091,"human, this, virus, with, the, was, isolated, in, of"
48961,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.090909091,"have, that, the, of, with, to, human, than"
48962,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.090909091,"to, a, wet, animal, market, in"
48963,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.090909091,"the, of, suggesting, that, animal, to, by"
48964,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.090909091,"virus, in, guangdong, province, with, the, of"
48965,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.090909091,"evidence, to, that, the, of, and, may, as, for, than"
48966,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.090909091,"the, sars, as, from, in, or"
48967,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.090909091,"of, the, virus, from, in, with, and"
48968,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.090909091,"a, and, in, host, or, humans"
48969,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.090909091,"that, a, host, to, or, collected"
48970,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.090909091,"a, study,, it, that, the, same, and, for, to, host, by"
48971,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.090909091,"another, study, suggested, the, host, of, and, an, animal, intermediate"
48972,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.090909091,"that, to, identical, as, the, host"
48973,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.090909091,"the, of, and, that, humans, at, in"
48974,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.090909091,"in, to, of, the, virus, and, was"
48975,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.090909091,"of, the, as, in, from, a"
48976,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.090909091,"of, that, the, a, from, as, intermediate"
48977,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.090909091,"the, of, a, human, as, and"
48978,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.090909091,"to, a, virus, that, bats, and, the, as, intermediate"
48979,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.090909091,"and, that, from, the, bat, coronavirus, was, at, of"
48980,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.090909091,"to, a, virus, that, from, and, was, the, as"
48981,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.090909091,"of, the, virus, and, closest, was, with, bat, coronavirus"
48982,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.090909091,"a, as, the, recombination, of, thus, and, be, in, with, that, to"
48983,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.090909091,"the, a, genome, of, to, with, that, from, and, horseshoe, bat"
48984,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.090909091,"a, and, the, of, virus, from, bat, in, china"
48985,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.090909091,"in, a, of, for, were, to, infected, suggesting, zoonotic"
48986,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.090909091,"the, of, in, from, market, that, this, at"
48987,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.090909091,"on, evidence, in, the, and, that, of, were, from, market"
48988,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.090909091,"the, market, animals, that, are, to, and, of"
48989,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.090909091,"is, with, a, and, of, the, market, in"
48990,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.090909091,"as, in, the, of, and, are, to, viruses, for, other, virus"
48991,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.090909091,"a, group, of, researchers, the, with, viruses, that, bats"
48992,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.090909091,"a, of, the, together, with, that, presence, and"
48993,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.090909091,"of, was, to, bats,, the, emergence, in, animals"
48994,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.090909091,"the, and, not, only, but, in, were"
48995,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.090909091,"all, the, and, in, not, that, of, is"
48996,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.090909091,"have, by, and, in, to, the, of, is"
48997,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.090909091,"in, a, of, for, were, to, with, that"
48998,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.090909091,"the, to, and, had, in"
48999,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.090909091,"that, the, a, market, selling, live, in, to, and"
49000,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.090909091,"to, sars-cov-2, in, the, all, this, that, for, is, of"
49001,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.090909091,"in, with, the, by, those, and, to, that, sars-cov-2, is, of"
49002,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.090909091,"and, in, were, to, be, that, the, of, is, likely, sars-cov-2"
49003,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.090909091,"a, the, of, is, and, to"
49004,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.090909091,"the, huanan, market, and"
49005,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.090909091,"the, of, a, covid-19"
49006,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.090909091,"in, to, the, animal"
49007,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.090909091,"the, to, a, that, this"
49008,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.090909091,"collected, and, that, is, of"
49009,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.090909091,"that, the, of, covid-19, in, but"
49010,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.090909091,"is, that, of, the, genomic"
49011,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.090909091,"the, in, of, that, also"
49012,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.090909091,"these, of, in, the, known"
49013,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.090909091,"the, is, also, that, sequences, in"
49014,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.090909091,"of, that, the, many, and"
49015,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.090909091,"is, the, known, in, of"
49016,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.090909091,"that, seafood, in, the, it, was"
49017,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.090909091,"since, sars-cov-2, the, and, in, that, of"
49018,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.090909091,"the, that, by, from, and, this, be"
49019,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.090909091,"the, by, of, in, and, that, this, a"
49020,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.090909091,"the, sars-cov-2, and, this, or, of"
49021,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.090909091,"that, and, in, were, market, on"
49022,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.090909091,"of, linked, to, the, huanan, that"
49023,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.090909091,"evidence, that, were, from, in, the, market, and, of, on"
49024,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.090909091,"of, the, presented, in, and, that"
49025,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.090909091,"that, to, and, on, the, of"
49026,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.090909091,"sars-cov-2, the, with, through"
49027,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.090909091,"a, sars-cov-2, with, the, virus"
49028,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.090909091,"to, sars-cov-2, a, the, that, with"
49029,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.090909091,"sars-cov-2, a, natural, humans"
49030,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.090909091,"to, the, sars-cov-2, natural, is"
49031,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.090909091,"on, the, that, through, natural, a"
49032,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","expended to make the simple point 

that COVID-19 had a natural origin.",0.090909091,"that, a, the"
49033,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","expended to make the simple point 

that COVID-19 had a natural origin.",0.090909091,"that, the"
49034,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","unnatural origin of SARS-CoV-2, but these people are 

simply wrong",0.090909091,"are, of, these"
49035,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.090909091,"found, that, sars-cov-2, to"
49036,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.090909091,"to, that, in, and"
49037,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.090909091,"from, in, to, and"
49038,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.090909091,"bats, china, found, coronaviruses"
49039,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.090909091,"that, to, sars-cov-2, coronaviruses"
49040,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.090909091,"in, to, that, sars-cov-2, and"
49041,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.090909091,"in, related, and, to, sars-cov-2"
49042,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.090909091,"to, and, in, bats"
49043,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.090909091,"in, china, and, were, found"
49044,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.090909091,"the, hypothesis, as"
49045,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.",0.090909091,"host, and, the, species."
49046,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.090909091,"the, of, and, which, a"
49047,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.090909091,"the, to, and, which, reservoirs, viruses"
49048,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.090909091,"has, in, and, before"
49049,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.090909091,"in, humans, and, sars-cov-2"
49050,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.090909091,"and, host, a, in, or, humans"
49051,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.090909091,"and, before, was, sars-cov-2, in, a"
49052,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.090909091,"sars-cov-2, has, and"
49053,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.090909091,"in, the, a, that, with"
49054,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.090909091,"a, the, that, sars-cov-2, genomic, in"
49055,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.090909091,"sars-cov-2, in, the, shows, that"
49056,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.090909091,"a, the, wiv, that, virus"
49057,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.090909091,"the, a, virus, with"
49058,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.090909091,"a, show, that"
49059,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.090909091,"that, spike, to, sars-cov-2"
49060,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.090909091,"a, this, the, that, to"
49061,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.090909091,"a, coronavirus, of, is, that"
49062,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.090909091,"a, that, it"
49063,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.090909091,"a, of, that, coronavirus"
49064,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.090909091,"of, through, that"
49065,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.090909091,"of, that, is, a"
49066,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.090909091,"a, of, sars-cov-2"
49067,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.090909091,"the, genetic, used"
49068,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.090909091,"one, the, of, have"
49069,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.090909091,"from, the, show"
49070,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.090909091,"genetic, the, used"
49071,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","atural  

selection in an animal host before zoonotic  

transfer;",0.090909091,"animal, in, zoonotic"
49072,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","natural selection in humans  

following zoonotic transfer",0.090909091,"in, natural"
49073,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.090909091,"that, sars-, cov-2, its, to"
49074,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.090909091,"the, is, identical, to, that"
49075,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.090909091,"ace2, sars-cov-2, spike, pangolin"
49076,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.090909091,"is, that, sars-cov-2, the, result, of"
49077,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.090909091,"the, for, of, all, to, that, in, this, is, sars-cov-2"
49078,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.090909091,"that, shows, the, sars-cov-2, in"
49079,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.090909091,"and, that, by, of"
49080,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.090909091,"that, the, of, can, a"
49081,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.090909091,"the, of, that, can"
49082,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.090909091,"the, by, a, that, can"
49083,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.090909091,"humans,, the, of, sars-cov-2"
49084,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.090909091,"t, was, in"
49085,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.090909091,"the, that, of, in, also"
49086,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.090909091,"can, the, of, that"
49087,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.090909091,"that, of, the, virus"
49088,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.090909091,"the, also, that, can, in"
49089,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.090909091,"a, the, with, of"
49090,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.090909091,"the, in, of, however,, and"
49091,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.090909091,"since, related, sars-cov-2, in"
49092,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.090909091,"the, and, related, in"
49093,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.090909091,"related, and, cleavage, the, is"
49094,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.090909091,"the, is, that, in, of, and, not, all"
49095,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.090909091,"since, and, the, that, of, sars-cov-2, in"
49096,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.090909091,"that, the, of, all, and, in"
49097,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.090909091,"and, not, the, of, that, sars-cov-2, in"
49098,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.090909091,"in, the, of, based, and"
49099,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.090909091,"the, observed, in, that"
49100,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.090909091,"sars-cov-2, including, and, of, coronaviruses"
49101,"no modifications were  

recorded for nonstructural proteins NSP7, NSP13  

and the structured and accessory proteins p6 and 8b.","In the 

case of MERS, dromedaries were the principal host.",0.090909091,"were, the"
49102,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.090909091,"is, to, and, in"
49103,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.090909091,"the, that, but, was, to"
49104,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.",0.090909091,"a, of, in, the, with"
49105,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.090909091,"that, a, their"
49106,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.090909091,"the, that, a, genome"
49107,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.090909091,"most, that, a, the, of"
49108,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.090909091,"the, that, of, coronavirus"
49109,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.090909091,"the, covid-19, of, a"
49110,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.090909091,"genome, bat, that, a"
49111,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.090909091,"a, animal, coronavirus, the"
49112,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.090909091,"evidence, that, a, animal"
49113,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.090909091,"that, the, virus, coronavirus"
49114,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.090909091,"that, a, coronavirus, found, in, the"
49115,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.090909091,"found, the, in, region"
49116,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.090909091,"a, in, that, the, virus, found"
49117,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.090909091,"the, region, a, in, ace2, that"
49118,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.090909091,"a, that, the, receptor, and, to"
49119,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.090909091,"in, the, of, indicated, that, to"
49120,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.090909091,"study, that, of, to, a, in, the"
49121,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.090909091,"to, that, viruses, in, human"
49122,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.090909091,"a, study, in, that, the, to, of"
49123,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.090909091,"is, based, on, the, in"
49124,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.090909091,"in, the, and, of, both"
49125,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.090909091,"to, in, bats, and"
49126,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.090909091,"in, the, and, to, of, cov"
49127,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.090909091,"and, in, to, the, of, bats"
49128,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.090909091,"the, to, which, from"
49129,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.090909091,"that, the, and, evidence, to"
49130,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.090909091,"the, from, and, which"
49131,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.090909091,"the, which, belongs"
49132,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.090909091,"the, that, animals, which"
49133,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.090909091,"to, the, cov,, which"
49134,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.090909091,"that, to, from"
49135,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.090909091,"the, evidence, indicates, that"
49136,hese close genetic relations suggest that they all have their ecological origin in bat populations,The COVID-19 most likely developed from bat origin coronaviruses,0.090909091,"origin, bat"
49137,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.090909091,"the, of, bat, that, these"
49138,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.090909091,"that, a, the, of, evidence, is"
49139,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.090909091,"the, is, that, of, from"
49140,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.090909091,"the, is, that, a, of"
49141,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.090909091,"the, of, as, intermediate, a, that, from"
49142,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.090909091,"the, of, that, a, bat"
49143,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.090909091,"which, have, a, of, is"
49144,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.090909091,"that, the, acid, of, receptor"
49145,"preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.090909091,"that, of, viruses"
49146,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.090909091,"that, the, genomic, and"
49147,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.090909091,"to, genomic, in, the, and"
49148,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.090909091,"and, intermediate, hosts, to, in, the"
49149,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.090909091,"that, to, in, intermediate"
49150,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.090909091,"animals, can, to, and"
49151,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.090909091,"in, zoonotic, to, and"
49152,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.090909091,"zoonotic, are, and"
49153,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.090909091,"in, to, be, zoonotic"
49154,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.090909091,"are, be, in, that, to"
49155,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.090909091,"are, in, to, originated"
49156,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.090909091,"viruses, in, to"
49157,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.090909091,"to, in, these"
49158,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.090909091,"these, viruses, to, in"
49159,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.090909091,"the, covid-19, in, to"
49160,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.090909091,"in, the, china"
49161,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.090909091,"is, the"
49162,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.090909091,"the, of, that, have"
49163,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.090909091,"of, later, the"
49164,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.090909091,"have, the, of, that"
49165,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.090909091,"the, of, have, which, in, was"
49166,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.090909091,"in, of, which, have"
49167,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.090909091,"is, the, to, was"
49168,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.090909091,"the, that, it, to"
49169,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.090909091,"of, and, that, the, for"
49170,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.090909091,"that, and, for, to, the"
49171,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.090909091,"it, the, and, to, that"
49172,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.090909091,"is, to, the, bat"
49173,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.090909091,"covid-19, to, have, the, in"
49174,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.090909091,"of, the, in, between, 2019, and"
49175,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.090909091,"between, and, the, of, in, china"
49176,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.090909091,"all, the, and, in, that, of"
49177,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.090909091,"the, two, of, in, china"
49178,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.090909091,"and, have, the, are, all, guangdong"
49179,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.090909091,"animals, that, virus, were, with"
49180,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.090909091,"the, virus, which, with, that"
49181,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.090909091,"the, that, which, animals"
49182,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.090909091,"results, that, be, the"
49183,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.090909091,"in, the, covid-19, first"
49184,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.090909091,"the, of, two, in, china"
49185,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.090909091,"the, first, in"
49186,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.090909091,"that, the, animals, this"
49187,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.090909091,"contact, it, that, of, to"
49188,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.090909091,"to, have, the, in"
49189,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.090909091,"it, with, the, in"
49190,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.090909091,"this, of, living, in, the"
49191,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.090909091,"the, was, to, of, with"
49192,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.090909091,"to, of, it, that, in"
49193,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.090909091,"the, of, in, as, a"
49194,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.090909091,"the, of, known, these, in"
49195,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.090909091,"of, a, the, genus"
49196,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.090909091,"studies, a, the, of"
49197,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.090909091,"that, natural, the, species"
49198,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.090909091,"the, species, of"
49199,"ARS-CoV-2 is a 

natural virus, not a lab-created one.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.090909091,"is, natural"
49200,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.090909091,"is, from, bat, species, in"
49201,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.090909091,"the, species, is, by"
49202,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.090909091,"species, in, the"
49203,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.090909091,"only, bat, is, the"
49204,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.090909091,"may, in, bat, species."
49205,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.090909091,"the, in, and, even, of"
49206,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.090909091,"the, bats, of, bat, and"
49207,"The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.090909091,"the, and, host, species."
49208,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.090909091,"host, bats, and, in, the"
49209,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.090909091,"the, bat, or, of"
49210,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.090909091,"may, in, bats, or"
49211,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.090909091,"the, from, bats"
49212,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.090909091,"and, to, bats"
49213,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.090909091,"the, from, between, and"
49214,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.090909091,"between, and, the, from"
49215,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.090909091,"to, from, bats, the, and"
49216,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.090909091,"the, and, scenario, is"
49217,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.090909091,"bats, to, be"
49218,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.090909091,"and, to, the, is"
49219,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.090909091,"bats, the, host"
49220,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.090909091,"bats, by, the, found"
49221,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.090909091,"by, and, was, the"
49222,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.090909091,"closely, related, in, the, and"
49223,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.090909091,"host, and, the, in, bats"
49224,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.090909091,"in, an, intermediate, host"
49225,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.090909091,"another, bat, be, of, and"
49226,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.090909091,"to, in, or"
49227,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.090909091,"bats, are, to, be, the, of, may"
49228,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.090909091,"et, 2020), and, to, bats, the, of"
49229,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.090909091,"to, a, of, animal, and, the"
49230,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.090909091,"a, was, the, and, to, which, sars-cov"
49231,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.090909091,"have, the, and, of, virus, identical, to"
49232,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.090909091,"in, the, of, which, was, to, virus"
49233,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.090909091,"of, the, have, in, which, was"
49234,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.090909091,"a, the, of, and, wild, animals"
49235,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.090909091,"and, in, of"
49236,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.090909091,"in, the, of, and, patients"
49237,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.090909091,"a, of, in, the, and"
49238,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.090909091,"the, link, between, and"
49239,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.090909091,"the, of, in, and, a"
49240,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.090909091,"in, a, of, patients"
49241,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.090909091,"and, been, of, origin"
49242,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.090909091,"have, the, in, and, from"
49243,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.090909091,"sars-cov-2, isolated, from, the"
49244,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.090909091,"and, the, isolated, in, of"
49245,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.090909091,"is, have, the, in"
49246,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.090909091,"the, of, two, from, and"
49247,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.090909091,"two, from, the, and"
49248,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.090909091,"and, of, is, viruses, in"
49249,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.090909091,"the, on, with, sars-cov-2, at"
49250,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.090909091,"of, in, guangdong, province, with, the, virus"
49251,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.090909091,"in, of, sars-cov-2, on, amino, acid"
49252,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.090909091,"at, is, the, with, sars-cov-2"
49253,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","t some virus detected in pangolins 

were capable of infecting humans.",0.090909091,"were, in, pangolins"
49254,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","t some virus detected in pangolins 

were capable of infecting humans.",0.090909091,"were, in"
49255,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.090909091,"were, found, in, and, china"
49256,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.090909091,"et, al., by, in, china"
49257,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.090909091,"the, in, bats, southeast"
49258,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.090909091,"bats, by, the"
49259,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.090909091,"the, in, bats, by"
49260,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.090909091,"the, in, southeast"
49261,"t some virus detected in pangolins 

were capable of infecting humans.","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.090909091,"in, were"
49262,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.090909091,"their, in, which"
49263,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.090909091,"have, bats, the, and"
49264,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.",0.090909091,"that, of, transmission"
49265,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.",0.090909091,"of, that, viruses"
49266,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.",0.090909091,"viruses, provide, evidence, that"
49267,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.090909091,"the, of, covid-19"
49268,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.090909091,"the, of, and, that, a"
49269,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.090909091,"this, the, of, that"
49270,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.090909091,"the, of, that, a, and"
49271,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.090909091,"the, of, a, and, wild, animals"
49272,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.090909091,"a, of, and, the, animals"
49273,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.090909091,"the, and, a, that, of"
49274,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.090909091,"a, for, the, wild, is"
49275,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.090909091,"from, a, is"
49276,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.090909091,"the, most, likely, to"
49277,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.090909091,"to, the, from, a"
49278,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.090909091,"from, to, related, the, is, likely"
49279,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.090909091,"the, of, to, have, and, including"
49280,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.090909091,"several, have, the, and, of, to"
49281,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.090909091,"from, to, the, reservoir, of"
49282,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.090909091,"that, a, bat, has, of"
49283,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.090909091,"that, a, sars-cov-2, been"
49284,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.090909091,"that, has, been, a"
49285,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.090909091,"that, genome, a, bat"
49286,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.090909091,"has, a, human, and"
49287,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.090909091,"from, in, one, the, a, sars-cov-2, to"
49288,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.090909091,"the, other, sars-cov-2, and, from, a"
49289,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.090909091,"the, from, a, in, to, and"
49290,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.090909091,"the, sars-cov-2, hosts, and, other"
49291,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.090909091,"the, to, sars-cov-2, intermediate, malayan, and"
49292,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.090909091,"the, in, and, to, intermediate, hosts"
49293,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.090909091,"the, sars-cov-2, and, coronavirus, has, from"
49294,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.090909091,"sars-cov-2, has, the, with, and, to"
49295,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.090909091,"available, the, and"
49296,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.090909091,"on, and, in, the"
49297,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.090909091,"is, on, the, in"
49298,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.090909091,"and, very, the"
49299,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.090909091,"an, of, and, humans"
49300,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","zoonotic corona- 

viruses have become an increasing threat to human health,",0.090909091,"viruses, to"
49301,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.090909091,"virus, and, of"
49302,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.090909091,"and, virus, the, of"
49303,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.090909091,"zoonotic, the, for"
49304,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.090909091,"was, of, a"
49305,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.090909091,"of, sars-, cov-2, a, analysis"
49306,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.090909091,"a, of, data, that, the, or"
49307,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.090909091,"also, that, a, by, the, virus"
49308,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.090909091,"a, the, to, that, virus"
49309,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.090909091,"that, has, have, are, the"
49310,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.090909091,"that, the, have, or, a, of"
49311,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.090909091,"that, the, of, to, or"
49312,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.090909091,"to, virus, been, by, the"
49313,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.090909091,"wiv, a, virus, that, the"
49314,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","ARS-CoV-2 is a 

natural virus, not a lab-created one.",0.090909091,"natural, a"
49315,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.090909091,"are, in, with, bats,"
49316,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.090909091,"the, are, by"
49317,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.090909091,"the, with, in"
49318,The FCS of SARS-CoV-2 was not bioengineered—full stop.,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.090909091,"the, not"
49319,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.090909091,"the, other, by, in, coronavirus"
49320,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.090909091,"in, from, an, a, sars-cov-2"
49321,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.090909091,"that, sars-cov-2, to, bat"
49322,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.090909091,"in, a, from, that, intermediate"
49323,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.090909091,"to, sars-cov-2, intermediate, bat"
49324,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.090909091,"that, in, to, intermediate"
49325,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.090909091,"an, intermediate, host, in"
49326,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.090909091,"host, that, collected, a, or, to"
49327,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.090909091,"is, sars-cov-2, to, that"
49328,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.090909091,"the, that, of, humans"
49329,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.090909091,"is, with, of, the"
49330,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.090909091,"of, the, with, that, could"
49331,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.090909091,"that, the, an, of"
49332,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.090909091,"no, that, to, sars-cov-2"
49333,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.090909091,"to, that, sars-cov-2, in"
49334,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.090909091,"to, in, may, recent, sars-cov-2"
49335,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.090909091,"a, the, of, that, not, but"
49336,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.090909091,"he, that, of"
49337,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.090909091,"the, have, reservoirs, and"
49338,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.090909091,"the, many, and"
49339,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.090909091,"that, in, the, it, was, not"
49340,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.090909091,"have, the, of, to, a, and, as"
49341,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.090909091,"sars-cov-2, a, and, was, in, before"
49342,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.090909091,"sars-cov-2, the, and, in, not, that, of"
49343,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",The FCS of SARS-CoV-2 was not bioengineered—full stop.,0.090909091,"was, not, the, of, sars-cov-2"
49344,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","S1/S2 cleavage sites of coronaviruses are frequently modi- 

fied by insertions or deletions (indels) during evolution",0.090909091,"are, by, of"
49345,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.090909091,"from, for, the"
49346,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.090909091,"the, from, animal"
49347,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.090909091,"more, from, the"
49348,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.090909091,"for, the, zoonotic"
49349,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.090909091,"cov, the, more, for"
49350,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.090909091,"the, from, animal, for"
49351,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.090909091,"sars-cov-2, to, found, bat"
49352,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.090909091,"the, to, was"
49353,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.090909091,"be, to, the"
49354,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.090909091,"most, human, virus"
49355,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.090909091,"that, the, of, a, genetic"
49356,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.090909091,"natural, of, the, a, that"
49357,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.090909091,"that, sars-cov-2, natural, are, the"
49358,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.090909091,"it, with, are, both, sars-cov-2, the"
49359,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.090909091,"these, are, sars-cov-2, with, that, the, is"
49360,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.090909091,"the, that, sars-cov-2, with, of"
49361,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.090909091,"human, and, a, viral"
49362,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.090909091,"the, and, of, human"
49363,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.090909091,"a, and, the, as"
49364,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.090909091,"a, of, and, the, as"
49365,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.090909091,"the, diversity, of"
49366,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.090909091,"the, of, as, a, human, and"
49367,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.090909091,"has, and, human, a"
49368,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.090909091,"the, of, a, has"
49369,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.090909091,"the, have, been, of, and"
49370,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.090909091,"the, of, and, in, reviewed, our, is"
49371,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.090909091,"of, to, the, in, been"
49372,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.090909091,"sars-cov-2, have, been, in"
49373,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.090909091,"the, of, is, by, natural, in, to"
49374,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.090909091,"the, is, have, in, of, to, by, and"
49375,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.090909091,"sars-cov-2, is, natural, to, the"
49376,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.090909091,"the, pangolin, is, bat"
49377,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.090909091,"the, is, its, in"
49378,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.090909091,"the, is, not, in"
49379,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.090909091,"the, a, from, an"
49380,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.090909091,"bat, by, is, which, the"
49381,"Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.090909091,"based, on, the, in, is"
49382,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.090909091,"the, from, a, bat, pangolin"
49383,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.090909091,"and, to, be"
49384,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.090909091,"and, to, an, be"
49385,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.090909091,"has, and, identity"
49386,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.090909091,"to, has, and, an"
49387,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.090909091,"and, to, an"
49388,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.090909091,"that, sars-cov-2, was, from"
49389,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.090909091,"that, and, from"
49390,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.090909091,"and, that, to"
49391,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.090909091,"and, from, to, ratg13"
49392,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.090909091,"bats, of, and, are, to"
49393,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.090909091,"sars-cov-2, to, are, coronaviruses, bats"
49394,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.090909091,"of, that, sars-cov-2, to, coronaviruses"
49395,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.090909091,"of, and, amino, acid, sars-cov-2"
49396,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.090909091,"in, sars-cov-2, amino, acid, of, on"
49397,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.090909091,"to, and, of, that, ratg13, in"
49398,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.090909091,"with, genome, of"
49399,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.090909091,"genome, of, bat, ratg13, overall"
49400,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.090909091,"of, ratg13, sars-cov-2"
49401,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.090909091,"sars-cov-2, with, than, similarity"
49402,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.090909091,"bat, of, sars-cov-2"
49403,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.090909091,"from, as, that, the"
49404,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.090909091,"the, and, be, to"
49405,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.090909091,"this, to, the, that, been"
49406,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.090909091,"and, the, be, that, this, from, by"
49407,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.090909091,"from, the, origin, between, and"
49408,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.090909091,"the, is, and, but"
49409,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.090909091,"additional, that, the, is"
49410,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.090909091,"of, to, with, sars-cov-2, the"
49411,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.090909091,"closest, bat, similar, sars-cov-2"
49412,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.090909091,"from, sars-cov-2, bat, and"
49413,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.090909091,"of, sequences, from, bat"
49414,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.090909091,"the, of, sars-cov-2, which, ace2"
49415,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.090909091,"to, which, sars-cov-2, the"
49416,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.090909091,"the, animals, to, in, of, bats,, emergence, was"
49417,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.090909091,"in, these, to"
49418,"Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.090909091,"nature, is, a, coronavirus"
49419,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.090909091,"a, that, the, beta, in"
49420,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.090909091,"the, is, that, sequences, in, also"
49421,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.090909091,"can, the, that, by, a"
49422,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.090909091,"the, in, that, can, also"
49423,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.090909091,"that, is, naturally, the"
49424,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.090909091,"that, sequences, also, a, the"
49425,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.090909091,"is, the, coronavirus, sequence, in"
49426,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.090909091,"the, of, that, to, in, this, origin"
49427,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.090909091,"the, sars-cov-2, to, in, of, this, be"
49428,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.090909091,"the, to, and, that, origin, in"
49429,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.090909091,"to, the, emergence, of, and"
49430,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.090909091,"studies, suggest, that, the"
49431,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.090909091,"studies, that, sars-cov-2"
49432,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.090909091,"the, results, that, sars-cov-2"
49433,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.090909091,"the, that, sars-cov-2, for"
49434,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.090909091,"and, the, bat, also, to, a, cluster, that"
49435,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.090909091,"a, the, bat, from, pangolin"
49436,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.090909091,"sars-cov-2, and, from, bat"
49437,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.090909091,"sars-cov-2, also, to, the"
49438,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.090909091,"to, the, results, and, that"
49439,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.090909091,"the, from, and, a"
49440,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.090909091,"hosts, and, are"
49441,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.090909091,"sars-cov-2, for, and"
49442,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.090909091,"the, virus, that"
49443,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.090909091,"is, to, a, of, the"
49444,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.090909091,"the, genome, of, that, a, in, to"
49445,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.090909091,"the, that, a, virus, found, in"
49446,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.090909091,"a, the, it, that, is, most"
49447,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.090909091,"a, to, the, bats, as"
49448,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.090909091,"phylogenetic, to, the, of"
49449,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.090909091,"the, that, many, of, and"
49450,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.090909091,"a, of, the, genus"
49451,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.090909091,"a, of, the, in, sars-cov-2"
49452,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.090909091,"sars-cov-2, a, by, the, in"
49453,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.090909091,"by, genome, the, sars-cov-2"
49454,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.090909091,"in, the, of, sars-cov-2, a"
49455,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.090909091,"a, in, sars-cov-2, the, bat"
49456,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.090909091,"in, china, by, et, al."
49457,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.090909091,"sars-cov-2, a, bat, in"
49458,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.090909091,"to, a, of, from"
49459,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.090909091,"sequences, of, from, bat"
49460,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.090909091,"bat, similarity, to, of"
49461,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.090909091,"in, the, a, to, and, for"
49462,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.090909091,"the, ratg13, about, sars-cov-2"
49463,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.090909091,"sars-cov-2, a, similarity, to"
49464,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.090909091,"of, to, found, in, pangolin, sequences"
49465,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.090909091,"of, have, in, which"
49466,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.090909091,"sars-cov-2, could, an, are, in"
49467,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.090909091,"study, that, in, sars-cov-2"
49468,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.090909091,"in, that, sars-cov-2, with"
49469,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.090909091,"they, that, sars-cov-2"
49470,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.090909091,"one, virus, to, sars-cov-2"
49471,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.090909091,"the, spike, and, a, of, in, other"
49472,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.090909091,"other, coronavirus, and, in, the, of"
49473,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.090909091,"this, of, the, than, in, that"
49474,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.090909091,"and, a, novel, the, coronavirus, natural, of"
49475,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.090909091,"protein, sars-cov-2,, than, that, of"
49476,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.090909091,"and, the, that, of, in, this, a, by"
49477,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.090909091,"a, natural, that, through, on, the"
49478,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.090909091,"by, coronavirus, in, the, other"
49479,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.090909091,"this, and, the, that, originated, in"
49480,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.090909091,"in, the, of, that, mutations, features"
49481,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.090909091,"show, that, in"
49482,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.090909091,"presented, in, the, and, that, of"
49483,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.090909091,"pangolin, to, sars-cov-2, is"
49484,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.090909091,"believe, that, the, of"
49485,"expended to make the simple point 

that COVID-19 had a natural origin.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.090909091,"the, that"
49486,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.090909091,"the, is"
49487,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.090909091,"the, is, naturally, that"
49488,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.090909091,"of, the, that, naturally"
49489,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.090909091,"on, the, that, to, in"
49490,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.090909091,"in, the, possible, bats"
49491,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.090909091,"in, these, viruses, to"
49492,"preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.090909091,"provide, evidence, that, viruses"
49493,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.090909091,"the, results, that, to, and"
49494,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.090909091,"that, bats, are, the"
49495,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.090909091,"that, the, this, is"
49496,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.090909091,"sars-cov-2, bats, cov, the"
49497,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.090909091,"that, the, with, than"
49498,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.090909091,"the, is, only, bat"
49499,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.090909091,"is, at, with, sars-cov-2, the"
49500,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.090909091,"the, for, cov, more"
49501,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.090909091,"the, been, from, and"
49502,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.090909091,"the, 1ab, that, of"
49503,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.090909091,"been, and, the, sars-cov-2"
49504,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.090909091,"coronavirus, from, and, sars-cov-2, has, the"
49505,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.090909091,"viruses, and, sars-cov-2, this, that, the"
49506,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.090909091,"to, sars-cov-2, in, the, and, that"
49507,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.090909091,"the, in, and, that, this, originated"
49508,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same",0.090909091,"the, had, and"
49509,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.090909091,"are, that, sars-cov-2, and, is, viruses, in"
49510,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.090909091,"the, that, these, are, with, sars-cov-2, is"
49511,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.090909091,"this, that, sars-cov-2, in, pa"
49512,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.090909091,"that, the, and, are, origin, sars-cov-2, than"
49513,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.090909091,"the, are, in, sars-cov-2, and"
49514,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.090909091,"the, is, in, with, to, host"
49515,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.090909091,"the, sars-cov-2, likely, in"
49516,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.090909091,"the, likely, to, in"
49517,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.090909091,"the, same, in, pangolin"
49518,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.090909091,"the, which, with, sars-cov-2"
49519,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.090909091,"the, to, which, cov,"
49520,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.090909091,"which, in, the, with"
49521,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.090909091,"the, and, in, is, to, by, ratg13"
49522,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.090909091,"with, the, and, of, to, that, in, is, sars-cov-2, those, by"
49523,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.090909091,"the, of, to, and, cov, in"
49524,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.090909091,"the, of, or"
49525,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.090909091,"or, of, the, bat"
49526,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.090909091,"more, than, the, that"
49527,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.090909091,"in, bats, sars-cov-2, the"
49528,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.090909091,"the, in, that, this"
49529,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.090909091,"sars-cov-2, similarity, between, and, bat"
49530,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.090909091,"than, the, and, that"
49531,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.090909091,"the, that, bat, and, sars"
49532,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.090909091,"the, that, sars-cov-2, than"
49533,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.090909091,"the, origin, that, sars-cov-2"
49534,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.090909091,"that, the, sars-cov-2, same"
49535,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.090909091,"the, sars-cov-2, that, bat"
49536,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.090909091,"the, that, sars-cov-2, ratg13"
49537,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.090909091,"are, the, that, bats"
49538,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.090909091,"and, the, of, or, pangolin"
49539,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.090909091,"and, the, or, of, sars-cov-2, this"
49540,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.090909091,"the, of, sars-cov-2, pangolin"
49541,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.090909091,"the, sars-cov-2, or"
49542,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.090909091,"that, the, bat, same, viruses"
49543,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.090909091,"the, is, that, and, also"
49544,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.090909091,"are, the, they, have, and"
49545,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.090909091,"the, have, with, sars-cov-2"
49546,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.090909091,"are, the, all, and, have, guangdong"
49547,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.090909091,"that, or, in, bats"
49548,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.090909091,"in, that, bats"
49549,"Bats have been reported as being the rich source of 

coronaviruses","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.090909091,"bats, have"
49550,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.090909091,"or, in, bats, may"
49551,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.090909091,"in, sars-cov-2, this, that, pa"
49552,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.090909091,"the, of, that, as, bats"
49553,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.090909091,"the, as, that, and, to"
49554,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.090909091,"that, the, may, have, as, of"
49555,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.090909091,"the, have, to, and, may"
49556,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.090909091,"that, the, sars-, cov-2, and"
49557,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.090909091,"sars-, and, are, to, sars-cov-2, the"
49558,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.090909091,"may, than, the, of, that, for, as, to, and, evidence"
49559,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.090909091,"and, of, sars-cov-2, the, for, to"
49560,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.090909091,"are, and, sars-cov-2, that, the, origin, than"
49561,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.090909091,"from, of, sequences, in, the, and"
49562,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.090909091,"the, and, in, of, based"
49563,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.090909091,"and, in, the, of, origin"
49564,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.090909091,"origin, the, from, between, and"
49565,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.090909091,"on, and, that, of"
49566,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.090909091,"on, the, and, that, of, to"
49567,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.090909091,"studies, a, of, the"
49568,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.090909091,"the, also, a, that, sequences"
49569,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.090909091,"of, more, than, that, with"
49570,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.090909091,"to, with, the, of, bat"
49571,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.090909091,"more, to, the, than"
49572,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.090909091,"are, the, to, a"
49573,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.090909091,"has, sars-cov-2, and, with"
49574,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.090909091,"pangolin-cov, sars-cov-2, with"
49575,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.090909091,"sars-cov-2, has, that"
49576,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.090909091,"and, to, sars-cov-2, has"
49577,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.090909091,"to, that, has, and"
49578,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.090909091,"sars-cov-2, to, with, that"
49579,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.090909091,"to, and, of, is"
49580,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.090909091,"sars-cov-2, of, the, and, with"
49581,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.090909091,"is, the, and, but"
49582,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.090909091,"the, showed, identity, sars-cov-2"
49583,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.090909091,"the, with, sars-cov-2, by"
49584,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.090909091,"the, from, for"
49585,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.090909091,"and, revealed, the"
49586,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.090909091,"the, bat-sl-cov-2, and"
49587,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.090909091,"the, bat-sl-cov-2, from"
49588,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.090909091,"and, that, of, in"
49589,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.090909091,"and, the, in, of"
49590,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.090909091,"in, the, sars-cov-2, and"
49591,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.090909091,"in, sars-cov-2, the, of"
49592,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.090909091,"and, of, that, in"
49593,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.090909091,"the, number, of, that"
49594,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.090909091,"have, for, the, of, that"
49595,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.090909091,"bats, and, have, the"
49596,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.090909091,"the, of, that, number"
49597,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.090909091,"similarity, with, sars-cov-2, than"
49598,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.090909091,"with, the, for, and"
49599,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.090909091,"is, with, sars-cov-2, the"
49600,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.090909091,"and, the, to"
49601,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.090909091,"the, and, in, to"
49602,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.090909091,"and, sars-cov-2, to, in, the"
49603,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.090909091,"in, are, and, sars-cov-2, the"
49604,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.090909091,"the, of, and, in, virus, that"
49605,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.090909091,"and, the, natural, of, pangolin"
49606,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.090909091,"of, the, that, sars-cov-2, and, at"
49607,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.090909091,"sars-cov-2, virus, that"
49608,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.090909091,"the, recombination, be, of, and"
49609,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.090909091,"bat, that, the, of, and"
49610,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.090909091,"the, from, bat-sl-cov-2"
49611,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.090909091,"the, features, of, mutations, in, that"
49612,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.090909091,"the, sars-cov-2, pangolin, of"
49613,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.090909091,"virus, has, of, origin"
49614,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.090909091,"that, the, virus, bats, to"
49615,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.090909091,"that, of, sars-cov-2, to, be"
49616,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.090909091,"to, bat-, the, sars-cov-2, has"
49617,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.090909091,"of, between, and, with"
49618,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.090909091,"a, of, the, to, with"
49619,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.090909091,"from, a, by, the, virus"
49620,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.090909091,"a, the, to, virus"
49621,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.090909091,"the, rbd, from, to, by"
49622,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.090909091,"by, a, with, to, the"
49623,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.090909091,"a, virus, with, the"
49624,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.090909091,"as, that, for, the"
49625,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.090909091,"the, sars-cov-2., that"
49626,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.090909091,"observed, the, in, that"
49627,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.090909091,"origin, for, the"
49628,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.090909091,"in, for, origin, that"
49629,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.090909091,"be, that, sars-cov-2"
49630,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.090909091,"sars-cov-2, likely, that"
49631,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.090909091,"likely, to, that"
49632,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.090909091,"be, to, sars-cov-2"
49633,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.090909091,"that, sars-cov-2, they"
49634,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.090909091,"the, sars-cov-2, and, host"
49635,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.090909091,"of, the, animal, and, an, study, another, suggested, intermediate, host"
49636,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.090909091,"be, bat, another, of, and"
49637,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.090909091,"sars-cov-2, the, bat"
49638,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.090909091,"a, virus, sars-cov-2"
49639,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.090909091,"sars-cov-2, the, a"
49640,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.090909091,"cov, and, the, sars-cov-2"
49641,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.090909091,"a, sars-cov-2, be, suggesting"
49642,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.090909091,"of, that, for, corona-, virus"
49643,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.090909091,"the, virus, a, in"
49644,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.090909091,"of, the, virus, type"
49645,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.090909091,"at, in, has, the"
49646,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.090909091,"that, the, in, from, a"
49647,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.090909091,"the, human, animal, for, be"
49648,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.090909091,"from, animal, the, for"
49649,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.090909091,"to, with, the, of, and"
49650,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.090909091,"to, with, the, natural"
49651,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.090909091,"the, of, to, what"
49652,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.090909091,"the, natural, to, and"
49653,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.090909091,"the, of, not, is"
49654,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.090909091,"of, with, to, and, the"
49655,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.090909091,"identified, in, bat"
49656,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.090909091,"of, sars-cov-2, a, in"
49657,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.090909091,"are, the, and, zoonotic"
49658,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.090909091,"are, zoonotic, and"
49659,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.090909091,"the, origin, for"
49660,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.090909091,"of, sars-cov-2, be, to"
49661,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.090909091,"for, to, were, in"
49662,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.090909091,"of, for, in, found, a, to, that"
49663,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.090909091,"in, that, be, sars-cov-2, infected"
49664,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.090909091,"infected, to, a, in, for, were, suggesting, zoonotic, of"
49665,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.090909091,"that, in, for, of, were, to, with, a"
49666,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.090909091,"zoonotic, in, be, to"
49667,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.090909091,"in, of, a, patients"
49668,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.090909091,"in, of, to, sars-cov-2, that"
49669,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.090909091,"in, that, origin, for"
49670,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.090909091,"suggesting, sars-cov-2, be, a"
49671,"Scientific reports published so far include  

hosts, such as bats (28), pangolins (29), cats  

(11), and dogs (30)",evidence suggests bats as its origin,0.090909091,"as, bats"
49672,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.090909091,"of, which, to, human, a, such, that, in, and"
49673,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.090909091,"natural, of, as, a, and"
49674,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.090909091,"of, a, zoonotic, and, in"
49675,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.090909091,"such, as, and, of, to, that, natural"
49676,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.090909091,"identity, in, with"
49677,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.090909091,"in, the, with, which"
49678,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.090909091,"the, at, has, in"
49679,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.090909091,"the, natural, of, beta-coronaviruses"
49680,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.090909091,"the, that, similar, to"
49681,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.090909091,"that, a, natural, of, the"
49682,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.090909091,"that, naturally, of, the"
49683,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.090909091,"is, the, to, that, in, and"
49684,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.090909091,"that, sars-cov-2, natural, and, are, the"
49685,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.090909091,"the, and, of, to, that, were, in, is, sars-cov-2, likely, be"
49686,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.090909091,"the, related, to, from, is, likely"
49687,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.090909091,"than, of, the, to"
49688,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.090909091,"the, is, of, known, in"
49689,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.090909091,"the, is, coronavirus, sequence, in"
49690,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.090909091,"the, of, to, that, decreased, and"
49691,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.090909091,"that, has, a, and, not"
49692,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.090909091,"the, region, that, ace2, a, in"
49693,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.090909091,"to, bat, ratg13, and, that"
49694,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.090909091,"is, and, bat, to, that, in"
49695,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.090909091,"and, of, to, it, that, is"
49696,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.090909091,"is, related, to, in"
49697,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.090909091,"to, it, that, in, of"
49698,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.090909091,"viruses, of, in, is, and"
49699,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.090909091,"in, to, that, of, and, ratg13"
49700,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.090909091,"of, is, and, to"
49701,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.090909091,"including, coronaviruses, of, and"
49702,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.090909091,"research, found, of, sars-cov-2"
49703,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.090909091,"sars-cov-2, including, and, coronaviruses, of"
49704,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.090909091,"intermediate, host, with, the"
49705,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.090909091,"to, the, also, as, an"
49706,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.090909091,"to, an, the, of"
49707,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.090909091,"one, of, the, have"
49708,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.090909091,"with, the, of, s, protein"
49709,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.090909091,"is, the, to, ratg13,"
49710,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.090909091,"to, than, the, key, amino"
49711,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.090909091,"on, the, of, to, in, zoonotic"
49712,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.090909091,"the, sars-cov-2, to, in, of, be"
49713,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.090909091,"with, the, of, sars-cov-2, and, genetic, analysis"
49714,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.090909091,"the, similarity, of, sars-cov-2, and"
49715,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.090909091,"the, to, identity"
49716,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.090909091,"of, similarity, to, bat"
49717,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.090909091,"is, the, that, additional"
49718,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).",0.09039548,"such, as, and, it, to, was, by, the, of, that, sars-cov-2, have, been, in, a, infect"
49719,"The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.09039548,"the, of, in, a, have, been, to, infect, and, sars-cov-2, it, was, that, such, as, by"
49720,"The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.090361446,"the, of, is, in, a, have, coronaviruses, to, and, sars-cov-2, site, human, other, naturally, insertion"
49721,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).",0.090361446,"the, site, insertion, sars-cov-2, and, have, to, a, of, is, in, other, human, coronaviruses, naturally"
49722,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).",0.090361446,"the, been, identified, as, a, species, of, mers-cov, that, bats,, to, humans, by, such, and"
49723,"The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.090361446,"the, of, a, been, identified, species, to, humans, mers-cov, and, that, bats,, such, as, by"
49724,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.090225564,"the, of, researchers, a, by, with, found, these, were, and, that, approximately"
49725,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.090225564,"by, a, of, researchers, the, found, that, were, and, approximately, these, with"
49726,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.090225564,"et, al., that, the, to, these, by, with, in, well, of, and"
49727,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.090225564,"the, and, in, with, these, by, of, well, to, et, al., that"
49728,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.090163934,"we, sars-cov-2, and, both, of, the, in, were, their, that, zoonotic"
49729,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.090163934,"as, a, of, the, and, were, it, with, for, from, host"
49730,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.090163934,"of, the, we, that, sars-cov-2, and, zoonotic, in, were, both, their"
49731,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.090163934,"in, the, a, to, bat, with, coronaviruses, these, and, recombination, events"
49732,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.090163934,"with, the, of, were, as, a, host, for, it, from, and"
49733,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.090163934,"had, from, and, made, to, this, for, the, of, in, a"
49734,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.090163934,"a, coronaviruses, to, recombination, events, in, with, these, the, bat, and"
49735,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.090163934,"in, a, of, to, made, the, from, for, this, and, had"
49736,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.09009009,"in, a, of, to, coronaviruses, the, which, bat, and, other"
49737,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.09009009,"sars-cov-2, of, the, have, to, animals, in, that, spillover, may"
49738,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.09009009,"the, was, for, to, with, as, and, could, of, at"
49739,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.09009009,"to, the, sars, as, and, of, from, sequence, that, genome"
49740,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.09009009,"the, of, to, bat, novel, moreover,, and, that, sars, approximately"
49741,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.09009009,"in, the, of, that, sars-cov-2, animals, may, have, to, spillover"
49742,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.09009009,"and, the, that, its, for, of, into, in, this, a"
49743,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.09009009,"the, genome, sequence, of, that, from, to, as, and, sars"
49744,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.09009009,"the, and, which, to, a, of, in, other, bat, coronaviruses"
49745,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.09009009,"as, the, was, to, at, with, of, could, for, and"
49746,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.09009009,"moreover,, and, that, the, novel, approximately, to, sars, of, bat"
49747,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.09009009,"the, of, to, bat, it, likely, that, as, reservoir, its"
49748,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.09009009,"and, the, of, a, that, into, this, in, for, its"
49749,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.09009009,"the, of, to, bat, as, that, likely, it, its, reservoir"
49750,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.09,"to, sars-cov-2, a, of, in, the, and, has, that"
49751,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.09,"the, of, large, number, in, to, that, were, it"
49752,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.09,"that, from, in, the, a, at, animals, and, are"
49753,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.09,"the, in, of, presence, with, that, animal, and, market"
49754,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.09,"in, of, from, two, at, to, least, were, and"
49755,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.09,"from, in, the, market, a, animals, and, of, animal"
49756,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.09,"suggests, that, from, in, the, a, animals, of, may"
49757,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.09,"it, is, that, a, if, the, of, at, sars-cov-2’s"
49758,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.09,"in, of, to, the, we, are, virus, for, as"
49759,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.09,"at, the, institute, of, and, in, we, virus, we’ve"
49760,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.09,"have, by, and, in, to, the, of, sars-cov-2, is"
49761,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.09,"as, in, the, of, are, we, to, for, virus"
49762,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.09,"in, the, of, and, at, institute, we, we’ve, virus"
49763,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.09,"that, the, of, in, animals, were, not, we, a"
49764,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.09,"a, the, of, in, we, animals, that, not, were"
49765,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.09,"the, of, were, that, a, in, evidence, or, to"
49766,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.09,"in, of, to, the, which, this, had, than, virus"
49767,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.09,"the, of, from, that, virus, to, coronavirus, is, and"
49768,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.09,"and, the, to, selling, live, animals, in, further, that"
49769,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.09,"that, were, from, in, the, a, of, cross-species, on"
49770,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.09,"after, the, of, that, virus, to, a, is, and"
49771,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.09,"that, the, selling, live, animals, in, to, and, further"
49772,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.09,"sars-cov-2, of, has, to, a, that, in, and, the"
49773,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.09,"sars-cov-2’s, that, it, at, the, if, a, of, is"
49774,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.09,"in, the, of, virus, to, a, is, closely, related"
49775,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.09,"the, of, a, or, to, covid-19, in, is, sars-cov-2"
49776,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.09,"that, bats, are, the, of, and, viruses, in, for"
49777,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.09,"the, as, a, of, that, to, infected, bat, and"
49778,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.09,"the, to, similar, bat, as, by, coronavirus, closest, at"
49779,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.09,"in, a, of, patients, to, with, suggesting, that, zoonotic"
49780,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.09,"were, at, least, two, of, from, in, and, to"
49781,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.09,"the, virus, is, to, that, of, and, coronavirus, from"
49782,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.09,"the, is, that, virus, to, after, a, of, and"
49783,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.09,"the, known, and, market, is, of, evidence, a, to"
49784,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.09,"that, the, of, in, to, or, were, evidence, a"
49785,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.09,"have, a, of, in, bats, the, known, as, horseshoe"
49786,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.09,"of, a, analysis, that, the, to, many, and, sars"
49787,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.09,"the, large, number, of, that, were, to, in, it"
49788,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.09,"this, of, to, the, than, in, which, had, virus"
49789,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.09,"genome, from, in, the, bat, of, virus, and, previously"
49790,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.09,"closest, bat, coronavirus, to, as, by, similar, at, the"
49791,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.09,"in, the, a, that, are, from, animals, at, and"
49792,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.09,"in, the, market, from, animal, and, a, of, animals"
49793,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.09,"from, in, the, of, suggests, that, a, animals, may"
49794,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.09,"on, in, the, of, a, from, that, were, cross-species"
49795,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.09,"the, presence, of, animal, with, and, market, that, in"
49796,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.09,"the, of, to, is, most, likely, on, a, that"
49797,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.09,"to, other, mammals, with, of, bats,, and, in, bats"
49798,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.09,"the, covid-19, is, of, sars-cov-2, or, to, a, in"
49799,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.09,"the, known, of, market, to, a, is, and, evidence"
49800,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.09,"the, to, a, of, is, on, most, likely, that"
49801,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.09,"and, the, of, viruses, are, bats, that, in, for"
49802,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.09,"the, bats, as, known, a, in, of, horseshoe, have"
49803,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.09,"to, in, of, bats,, with, mammals, bats, and, other"
49804,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.09,"and, the, of, infected, bat, to, as, a, that"
49805,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.09,"the, to, have, in, is, by, of, and, sars-cov-2"
49806,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.09,"to, the, sars, and, many, a, of, analysis, that"
49807,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.09,"in, of, the, from, bat, and, genome, previously, virus"
49808,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.09,"that, a, zoonotic, with, of, in, suggesting, patients, to"
49809,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.08988764,"of, a, large, number, viruses, in, species, coronaviruses"
49810,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.08988764,"infected, from, by, identified, were, of, and, species"
49811,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.08988764,"has, a, sars-cov-2, and, the, of, virus, in"
49812,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.08988764,"the, sars-cov-2, to, be, in, insertion, of, and"
49813,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.08988764,"its, that, human, as, the, a, of, has"
49814,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.08988764,"the, can, species, to, as, civets, and, sars-cov"
49815,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.08988764,"in, the, and, showing, that, of, were, from"
49816,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.08988764,"the, a, of, presence, was, virus, by, market"
49817,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.08988764,"the, of, that, has, its, as, a, human"
49818,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.08988764,"it, is, that, are, the, most, sars-cov-2, to"
49819,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.08988764,"of, covid-19, a, to, the, market, were, in"
49820,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.08988764,"the, to, virus, that, similar, and, in, its"
49821,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.08988764,"sars-cov-2, of, has, a, virus, in, and, the"
49822,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.08988764,"of, which, to, human, a, have, and, the"
49823,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.08988764,"which, the, these, species, of, to, as, and"
49824,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.08988764,"to, in, for, the, recent, zoonotic, of, and"
49825,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.08988764,"december, the, of, a, found, that, were, and"
49826,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.08988764,"a, was, in, an, animal, zoonotic, or, humans"
49827,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.08988764,"a, of, the, found, that, were, december, and"
49828,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.08988764,"coronaviruses, viruses, in, a, large, number, of, species"
49829,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.08988764,"the, virus, similar, to, and, that, its, in"
49830,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.08988764,"were, identified, from, of, species, infected, by, and"
49831,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.08988764,"recent, to, the, for, in, zoonotic, and, of"
49832,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.08988764,"that, were, in, bats, south, and, china, from"
49833,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.08988764,"presence, of, a, virus, the, market, was, by"
49834,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.08988764,"in, a, of, to, the, covid-19, were, market"
49835,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.08988764,"of, the, from, showing, that, and, in, were"
49836,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.08988764,"and, from, in, were, to, that, the, of"
49837,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.08988764,"that, were, from, bats, in, south, china, and"
49838,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.08988764,"a, zoonotic, was, an, animal, humans, or, in"
49839,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.08988764,"can, as, to, sars-cov, and, the, species, civets"
49840,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.08988764,"the, of, to, and, which, species, as, these"
49841,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.08988764,"the, insertion, sars-cov-2, and, to, be, of, in"
49842,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.08988764,"the, that, to, are, most, is, it, sars-cov-2"
49843,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.08988764,"in, the, and, that, of, were, to, from"
49844,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.089820359,"in, the, of, to, bat, had, with, found, sars,, sars-related, were, and, that, events, yunnan"
49845,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.089820359,"and, of, the, to, in, were, with, sars,, had, found, that, yunnan, bat, sars-related, events"
49846,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.08974359,"in, the, of, a, that, from, and"
49847,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.08974359,"bats, which, of, to, and, in, sars-cov"
49848,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.08974359,"the, it, would, that, of, sars-cov-2, from"
49849,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.08974359,"of, a, to, other, and, the, in"
49850,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.08974359,"that, for, palm, the, transmission, to, virus"
49851,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.08974359,"which, the, species, of, to, and, other"
49852,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.08974359,"and, the, of, to, are, bats, can"
49853,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.08974359,"in, and, to, sars-cov-2, bat, are, as"
49854,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.08974359,"in, the, and, of, positive, from, market"
49855,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.08974359,"in, the, that, of, samples, to, from"
49856,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.08974359,"of, to, the, in, they, had, virus"
49857,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.08974359,"because, we, and, to, the, viruses, in"
49858,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.08974359,"the, of, that, as, was, to, this"
49859,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.08974359,"a, positive, were, to, of, in, the"
49860,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.08974359,"a, on, and, were, of, in, the"
49861,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.08974359,"of, to, the, market, in, that, or"
49862,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.08974359,"in, the, of, to, they, virus, had"
49863,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.08974359,"that, the, of, market, in, to, or"
49864,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.08974359,"that, than, the, to, in, this, of"
49865,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.08974359,"the, that, of, to, by, and, a"
49866,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.08974359,"the, on, is, for, natural, reservoir, to"
49867,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.08974359,"the, of, in, and, virus, was, isolated"
49868,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.08974359,"the, and, to, that, of, bat, as"
49869,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.08974359,"a, of, in, revealed, with, the, virus"
49870,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.08974359,"on, in, the, that, of, were, from"
49871,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.08974359,"are, of, and, a, to, that, in"
49872,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.08974359,"of, to, the, that, was, this, as"
49873,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.08974359,"the, that, was, of, this, study, al."
49874,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.08974359,"bats, of, a, coron-, to, that, in"
49875,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.08974359,"sars-cov-2, of, has, a, virus, that, in"
49876,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.08974359,"in, the, at, found, from, to, and"
49877,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.08974359,"in, and, sars-cov-2, with, that, the, larger"
49878,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.08974359,"the, of, a, at, that, virus, from"
49879,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.08974359,"another, the, bat, high, animal, species, as"
49880,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.08974359,"in, the, to, that, of, bat, as"
49881,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.08974359,"the, of, are, bats, and, can, to"
49882,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.08974359,"to, on, the, natural, reservoir, is, for"
49883,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.08974359,"that, virus, transmission, to, for, the, palm"
49884,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.08974359,"revealed, a, with, the, of, virus, in"
49885,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.08974359,"at, the, and, in, found, from, to"
49886,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.08974359,"that, a, the, of, virus, at, from"
49887,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.08974359,"a, of, to, that, by, the, and"
49888,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.08974359,"have, that, the, for, a, of, and"
49889,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.08974359,"the, and, to, a, of, in, other"
49890,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.08974359,"in, a, of, to, the, were, positive"
49891,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.08974359,"a, the, of, and, in, on, were"
49892,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.08974359,"and, samples, the, huanan, of, in, a"
49893,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.08974359,"and, in, that, the, of, is, are"
49894,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.08974359,"sars-cov-2, the, of, that, it, would, from"
49895,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.08974359,"the, study, of, al., that, was, this"
49896,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.08974359,"a, samples, and, of, in, the, huanan"
49897,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.08974359,"in, the, market, positive, from, and, of"
49898,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.08974359,"samples, from, in, the, of, that, to"
49899,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.08974359,"on, in, the, of, from, that, were"
49900,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.08974359,"as, the, animal, another, bat, species, high"
49901,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.08974359,"the, of, in, and, that, coronavirus, a"
49902,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.08974359,"or, bats, be, carnivores, are, to, in"
49903,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.08974359,"sars-cov, and, in, to, bats, of, which"
49904,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.08974359,"other, the, species, which, to, of, and"
49905,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.08974359,"or, bats, are, in, to, carnivores, be"
49906,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.08974359,"and, virus, the, was, isolated, in, of"
49907,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.08974359,"not, a, the, in, its, by, from"
49908,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.08974359,"from, its, not, by, the, in, a"
49909,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.08974359,"this, of, to, the, than, in, that"
49910,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.08974359,"in, the, origin, of, these, and, reported"
49911,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.08974359,"of, the, and, are, 2, with, pangolin"
49912,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.08974359,"the, coronavirus, in, of, and, that, a"
49913,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.08974359,"2, of, pangolin, with, and, are, the"
49914,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.08974359,"in, the, and, we, to, viruses, because"
49915,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.08974359,"that, the, sars-cov-2, to, in, this, and"
49916,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.08974359,"sars-cov-2, in, and, larger, that, the, with"
49917,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.08974359,"sars-cov-2, to, are, as, and, in, bat"
49918,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.08974359,"the, of, that, to, bat, as, and"
49919,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.08974359,"that, the, of, bat, in, as, to"
49920,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.08974359,"reported, the, these, in, of, origin, and"
49921,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.08974359,"the, that, have, for, of, and, a"
49922,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.08974359,"of, and, that, a, in, are, to"
49923,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.08974359,"that, of, bats, to, a, in, coron-"
49924,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.08974359,"of, that, in, a, human, and, to"
49925,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.08974359,"the, is, that, of, are, and, in"
49926,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.089655172,"in, a, of, to, the, different, this, discovered, had, sars, at, than, virus"
49927,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.089655172,"this, sars, had, a, the, virus, than, of, in, at, different, discovered, to"
49928,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.089552239,"that, a, naturally, the, of, and"
49929,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.089552239,"bats, or, with, of, for, and"
49930,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.089552239,"with, bat, the, of, and, sars-cov"
49931,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.089552239,"the, been, of, that, from, to"
49932,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.089552239,"is, and, to, human, in, have"
49933,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.089552239,"that, a, was, the, sars-cov-2, is"
49934,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.089552239,"sars-cov-2, also, in, a, that, the"
49935,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.089552239,"the, of, and, a, are, to"
49936,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.089552239,"the, and, a, to, are, of"
49937,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.089552239,"of, the, that, 19, and, these"
49938,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.089552239,"of, and, that, sequences, in, similar"
49939,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.089552239,"of, any, other, and, the, known"
49940,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.089552239,"the, to, in, an, of, a"
49941,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.089552239,"bats, also, to, that, are, for"
49942,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.089552239,"with, the, of, that, an, is"
49943,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.089552239,"the, of, is, in, that, to"
49944,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.089552239,"the, in, was, to, animals, other"
49945,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.089552239,"the, of, and, are, to, be"
49946,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.089552239,"that, the, by, in, origin, and"
49947,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.089552239,"from, in, a, sars-cov-2, have, to"
49948,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.089552239,"to, and, have, as, are, sars-cov-2"
49949,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.089552239,"the, of, natural, a, to, that"
49950,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.089552239,"of, the, that, wuhan, and, these"
49951,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.089552239,"these, and, bat, ratg13, that, the"
49952,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.089552239,"that, and, in, were, at, a"
49953,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.089552239,"this, the, in, that, are, sars-cov-2"
49954,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.089552239,"we, that, the, sars-cov-2, and, viruses"
49955,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.089552239,"and, to, the, of, that, sars-cov-2"
49956,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.089552239,"that, the, of, sars-cov-2, and, at"
49957,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.089552239,"the, that, a, in, earliest, to"
49958,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.089552239,"the, of, geographic, is, in, a"
49959,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.089552239,"and, this, the, of, in, a"
49960,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.089552239,"the, animal, to, reservoirs, viruses, other"
49961,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.089552239,"to, the, in, of, and, a"
49962,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.089552239,"that, zoonotic, spillover, sars-cov-2, from, a"
49963,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.089552239,"and, were, to, that, the, of"
49964,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.089552239,"the, of, market, and, in, but"
49965,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.089552239,"of, the, in, a, those, animal"
49966,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.089552239,"sars-cov-2, have, from, to, a, in"
49967,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.089552239,"the, also, a, two, that, in"
49968,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.089552239,"is, that, known, are, and, in"
49969,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.089552239,"the, of, are, and, be, to"
49970,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.089552239,"wild, are, the, of, is, transmitted"
49971,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.089552239,"to, the, for, in, wild, of"
49972,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.089552239,"a, of, in, and, results, the"
49973,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.089552239,"in, it, that, the, and, of"
49974,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.089552239,"from, to, humans., that, in, a"
49975,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.089552239,"a, of, and, that, the, naturally"
49976,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.089552239,"is, that, sars-cov-2, was, a, the"
49977,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.089552239,"the, was, in, to, other, animals"
49978,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.089552239,"that, have, of, to, the, for"
49979,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.089552239,"the, and, that, a, sequence, to"
49980,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.089552239,"and, to, was, the, that, a"
49981,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.089552239,"in, with, the, by, clustering, of"
49982,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.089552239,"the, of, to, such, as, and"
49983,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.089552239,"coronavirus, from, and, has, to, the"
49984,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.089552239,"available, a, the, that, and, using"
49985,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.089552239,"and, sars-cov-2, pangolin, that, the, is"
49986,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.089552239,"with, bat, that, the, of, and"
49987,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.089552239,"the, of, and, that, sequences, to"
49988,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.089552239,"the, and, to, suggesting, that, of"
49989,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.089552239,"the, that, in, a, and, to"
49990,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.089552239,"a, virus, from, to, bats, and"
49991,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.089552239,"the, dromedary, camel, mers-cov, to, and"
49992,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.089552239,"the, sequence, of, bat, as, and"
49993,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.089552239,"the, is, of, human, with, and"
49994,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.089552239,"it, in, the, that, may, have"
49995,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.089552239,"study, of, to, is, coronavirus, the"
49996,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.089552239,"can, be, bat, to, of, more"
49997,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.089552239,"of, and, bats, for, with, or"
49998,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.089552239,"the, of, spike, to, or, another"
49999,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.089552239,"with, the, of, and, sars-cov, bat"
50000,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.089552239,"the, of, with, that, and, bat"
50001,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.089552239,"of, the, are, as, viruses, pangolin"
50002,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.089552239,"by, and, that, is, of, bat"
50003,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.089552239,"and, that, of, is, bats, likely"
50004,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.089552239,"of, and, to, species, usually, through"
50005,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.089552239,"available, of, the, covid-19, and, with"
50006,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.089552239,"by, was, in, the, virus, of"
50007,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.089552239,"coronaviruses, in, which, are, of, and"
50008,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.089552239,"the, of, as, intermediate, host,, to"
50009,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.089552239,"such, as, the, of, and, to"
50010,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.089552239,"the, as, of, bat, and, sequence"
50011,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.089552239,"sequence, the, of, coronavirus, from, that"
50012,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.089552239,"on, the, and, that, from, through"
50013,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.089552239,"of, the, are, transmitted, is, wild"
50014,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.089552239,"a, that, and, at, in, were"
50015,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.089552239,"the, in, of, and, a, china"
50016,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.089552239,"the, sequence, of, coronavirus, that, from"
50017,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.089552239,"the, coronavirus, a, sequence, that, in"
50018,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.089552239,"the, of, and, that, a, with"
50019,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.089552239,"and, the, that, of, sars-cov-2, a"
50020,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.089552239,"sequences, and, that, similar, of, in"
50021,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.089552239,"the, of, and, sequences, that, to"
50022,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.089552239,"in, similar, the, sequence, of, s"
50023,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.089552239,"sars-cov-2, and, in, coronaviruses, that, is"
50024,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.089552239,"the, of, and, that, sars-cov-2, at"
50025,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.089552239,"the, of, sars-cov-2, ace2, a, that"
50026,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.089552239,"to, the, of, as, intermediate, host,"
50027,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.089552239,"a, and, has, to, the, current"
50028,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.089552239,"the, have, to, in, market, at"
50029,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.089552239,"a, the, of, in, to, an"
50030,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.089552239,"such, as, of, have, been, in"
50031,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.089552239,"of, which, related, to, that, in"
50032,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.089552239,"these, as, and, the, of, to"
50033,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.089552239,"bats, are, also, for, that, to"
50034,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.089552239,"in, of, to, the, wild, for"
50035,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.089552239,"for, the, of, and, in, to"
50036,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.089552239,"a, from, bats, of, and, as"
50037,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.089552239,"covs, a, of, and, the, from"
50038,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.089552239,"the, of, as, a, to, human"
50039,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.089552239,"december, the, was, virus, to, and"
50040,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.089552239,"the, of, coronavirus, is, to, study"
50041,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.089552239,"in, to, the, sars-cov-2, from, an"
50042,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.089552239,"of, sars-cov-2-like, a, species, in, the"
50043,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.089552239,"the, from, a, to, of, with"
50044,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.089552239,"collected, of, the, were, and, with"
50045,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.089552239,"from, to, an, in, sars-cov-2, the"
50046,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.089552239,"the, and, also, has, in, to"
50047,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.089552239,"and, to, the, amino, in, rbd"
50048,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.089552239,"the, of, to, and, as, these"
50049,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.089552239,"also, that, sars-cov-2, a, the, in"
50050,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.089552239,"that, sars-cov-2, a, the, of, or"
50051,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.089552239,"in, a, with, and, sars-cov-2, the"
50052,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.089552239,"the, and, amino, in, rbd, to"
50053,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.089552239,"and, the, in, may, transmission, between"
50054,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.089552239,"it, that, the, in, may, have"
50055,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.089552239,"it, in, and, are, to, the"
50056,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.089552239,"a, the, that, sars-cov-2, and, in"
50057,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.089552239,"in, the, and, to, that, sars-cov-2"
50058,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.089552239,"and, in, to, that, the, sars-cov-2"
50059,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.089552239,"to, sars-cov-2, of, the, and, it"
50060,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.089552239,"a, the, of, and, that, to"
50061,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.089552239,"the, of, sars-cov-2, to, it, and"
50062,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.089552239,"evidence, that, with, the, of, to"
50063,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.089552239,"sars-cov-2, a, of, that, the, or"
50064,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.089552239,"bats, are, the, of, and, in"
50065,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.089552239,"viruses, to, the, animal, reservoirs, other"
50066,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.089552239,"of, a, sars-cov-2-like, in, species, the"
50067,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.089552239,"the, of, viruses, in, a, and"
50068,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.089552239,"a, was, the, sars-cov-2, and, to"
50069,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.089552239,"sars-cov-2, in, a, and, the, with"
50070,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.089552239,"it, in, the, and, are, to"
50071,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.089552239,"of, by, the, to, closely, related"
50072,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.089552239,"geographic, is, a, of, the, in"
50073,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.089552239,"that, the, reservoir, for, a, of"
50074,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.089552239,"in, a, human, cells, and, to"
50075,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.089552239,"the, and, 19, of, that, these"
50076,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.089552239,"these, and, that, the, wuhan, of"
50077,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.089552239,"available, a, that, and, using, the"
50078,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.089552239,"of, the, covid-19, and, available, with"
50079,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.089552239,"the, of, and, were, collected, with"
50080,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.089552239,"of, from, to, a, with, the"
50081,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.089552239,"a, from, to, of, and, on"
50082,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.089552239,"a, of, and, the, to, from"
50083,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.089552239,"that, in, the, virus, for, of"
50084,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.089552239,"in, a, that, the, earliest, to"
50085,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.089552239,"the, to, and, that, sequence, a"
50086,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.089552239,"to, the, for, in, and, of"
50087,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.089552239,"in, the, from, and, a, palm"
50088,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.089552239,"as, to, the, of, a, human"
50089,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.089552239,"to, december, virus, and, was, the"
50090,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.089552239,"the, known, of, and, any, other"
50091,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.089552239,"in, the, market, but, and, of"
50092,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.089552239,"are, that, and, is, known, in"
50093,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.089552239,"the, of, is, and, with, human"
50094,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.089552239,"in, the, all, that, is, of"
50095,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.089552239,"of, the, at, also, are, that"
50096,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.089552239,"a, that, sars-cov-2, from, zoonotic, spillover"
50097,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.089552239,"of, sars-cov-2, was, the, its, in"
50098,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.089552239,"on, the, that, through, and, from"
50099,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.089552239,"that, were, to, in, and, from"
50100,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.089552239,"in, and, that, were, to, from"
50101,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.089552239,"a, the, of, and, in, results"
50102,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.089552239,"the, of, natural, in, a, to"
50103,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.089552239,"the, of, and, a, in, to"
50104,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.089552239,"and, to, the, of, in, a"
50105,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.089552239,"the, to, spike, or, of, another"
50106,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.089552239,"that, the, of, sars-cov-2, ace2, a"
50107,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.089552239,"a, which, to, that, in, human"
50108,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.089552239,"the, is, that, of, in, all"
50109,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.089552239,"the, by, and, that, of, shows"
50110,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.089552239,"r., that, the, of, is, sars-cov-2"
50111,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.089552239,"sars-cov-2, is, and, coronaviruses, that, in"
50112,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.089552239,"and, have, to, is, in, human"
50113,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.089552239,"to, a, in, and, human, cells"
50114,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.089552239,"to, and, of, that, viruses, in"
50115,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.089552239,"a, and, the, of, in, china"
50116,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.089552239,"in, different, with, that, the, same"
50117,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.089552239,"and, may, transmission, the, between, in"
50118,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.089552239,"virus, bats, and, to, from, a"
50119,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.089552239,"of, more, to, bat, can, be"
50120,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.089552239,"of, bats, as, a, from, and"
50121,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.089552239,"from, a, and, to, of, on"
50122,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.089552239,"to, have, at, the, market, in"
50123,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.089552239,"the, of, market, in, was, a"
50124,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.089552239,"the, of, s, sequence, in, similar"
50125,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.089552239,"usually, and, of, to, through, species"
50126,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.089552239,"the, of, a, covs, from, and"
50127,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.089552239,"the, from, a, and, to, of"
50128,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.089552239,"the, of, that, been, to, from"
50129,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.089552239,"to, the, and, dromedary, camel, mers-cov"
50130,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.089552239,"a, and, identity, with, sars-cov-2, has"
50131,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.089552239,"and, sars-cov-2, with, bat, cov, that"
50132,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.089552239,"the, has, to, and, coronavirus, from"
50133,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.089552239,"the, current, to, a, and, has"
50134,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.089552239,"has, identity, with, and, sars-cov-2, a"
50135,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.089552239,"to, remains, the, scenario, and, be"
50136,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.089552239,"the, that, of, are, at, also"
50137,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.089552239,"the, by, also, has, a, that"
50138,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.089552239,"of, at, the, a, to, that"
50139,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.089552239,"the, of, is, with, that, an"
50140,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.089552239,"that, in, from, a, to, humans."
50141,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.089552239,"have, been, in, of, such, as"
50142,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.089552239,"a, origin, of, the, that, and"
50143,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.089552239,"of, are, coronaviruses, and, which, in"
50144,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.089552239,"and, the, to, be, that, is"
50145,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.089552239,"the, its, was, of, sars-cov-2, in"
50146,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.089552239,"in, also, two, the, that, a"
50147,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.089552239,"sequence, in, the, a, coronavirus, that"
50148,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.089552239,"a, the, has, also, by, that"
50149,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.089552239,"the, origin, and, by, that, in"
50150,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.089552239,"and, remains, to, be, the, scenario"
50151,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.089552239,"and, this, that, the, origin, is"
50152,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.089552239,"by, virus, the, was, in, of"
50153,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.089552239,"to, of, is, that, related, in"
50154,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.089552239,"a, of, the, that, and, which"
50155,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.089552239,"in, with, that, sars-cov-2, are, they"
50156,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.089552239,"have, to, for, the, of, that"
50157,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.089552239,"a, in, the, that, originated, laboratory"
50158,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.089552239,"sars-cov-2, the, and, viruses, to, in"
50159,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.089552239,"these, and, that, the, bat, ratg13"
50160,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.089552239,"the, that, same, in, with, different"
50161,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.089552239,"with, bat, cov, that, and, sars-cov-2"
50162,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.089552239,"this, that, the, origin, and, is"
50163,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.089552239,"clustering, of, in, the, with, by"
50164,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.089552239,"and, that, is, by, of, bat"
50165,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.089552239,"and, the, of, shows, that, by"
50166,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.089552239,"that, sars-cov-2, they, are, in, with"
50167,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.089552239,"the, this, that, sars-cov-2, are, in"
50168,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.089552239,"the, we, that, sars-cov-2, and, viruses"
50169,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.089552239,"sars-cov-2, have, to, are, as, and"
50170,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.089552239,"a, pangolin, with, sars-cov-2, to, the"
50171,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.089552239,"the, and, from, palm, a, in"
50172,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.089552239,"the, of, for, reservoir, a, that"
50173,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.089552239,"for, the, of, and, that, a"
50174,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.089552239,"and, the, that, for, of, a"
50175,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.089552239,"of, in, that, for, the, virus"
50176,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.089552239,"the, of, and, in, it, that"
50177,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.089552239,"the, of, and, that, in, this"
50178,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.089552239,"the, of, was, that, from, to"
50179,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.089552239,"in, sars-cov-2, this, that, the, is"
50180,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.089552239,"sars-cov-2, from, a, in, the, that"
50181,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.089552239,"the, in, that, originated, a, laboratory"
50182,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.089552239,"in, of, which, that, related, to"
50183,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.089552239,"a, to, in, which, that, human"
50184,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.089552239,"in, the, a, that, to, at"
50185,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.089552239,"in, the, those, animal, a, of"
50186,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.089552239,"in, the, of, that, a, to"
50187,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.089552239,"of, the, were, to, and, that"
50188,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.089552239,"and, that, is, likely, bats, of"
50189,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.089552239,"r., is, that, of, sars-cov-2, the"
50190,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.089552239,"the, of, and, suggesting, that, to"
50191,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.089552239,"in, to, the, has, also, and"
50192,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.089552239,"of, that, viruses, in, and, to"
50193,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.089552239,"in, that, is, related, to, of"
50194,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.089552239,"evidence, to, of, the, that, with"
50195,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.089430894,"and, the, of, to, a, new, that, in, for, which, virus"
50196,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.089430894,"the, and, in, their, with, of, a, as, to, that, virus"
50197,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.089430894,"as, the, palm, civets, and, to, for, example,, that, from, intermediate"
50198,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.089430894,"that, are, more, than, the, sars-cov-2, to, by, in, of, and"
50199,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.089430894,"the, of, to, bat, as, novel, genome, and, that, sars, from"
50200,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.089430894,"in, the, of, found, that, were, to, both, and, civet, related"
50201,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.089430894,"of, which, for, to, a, virus, that, in, and, new, the"
50202,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.089430894,"from, as, intermediate, that, to, for, example,, and, the, palm, civets"
50203,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.089430894,"and, both, of, the, to, related, civet, in, were, found, that"
50204,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.089430894,"and, from, in, were, found, to, be, that, the, of, bats"
50205,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.089430894,"the, genome, of, novel, that, from, to, bat, as, and, sars"
50206,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.089430894,"a, as, the, of, virus, and, in, with, that, their, to"
50207,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.089430894,"the, that, to, are, more, in, by, than, of, and, sars-cov-2"
50208,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.089430894,"to, the, bats, were, be, and, in, of, from, that, found"
50209,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.089285714,"a, of, in, bats, coronaviruses"
50210,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.089285714,"and, that, from, the, of"
50211,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.089285714,"the, that, of, and, from"
50212,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.089285714,"the, of, or, a, in"
50213,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.089285714,"the, of, that, a, in"
50214,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.089285714,"and, the, of, virus, from"
50215,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.089285714,"the, of, human, and, viruses"
50216,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.089285714,"of, bats, to, species, the"
50217,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.089285714,"to, in, bats, of, and"
50218,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.089285714,"sars-cov, and, sars-, to, the"
50219,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.089285714,"the, to, from, of, bat"
50220,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.089285714,"the, from, to, bat, and"
50221,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.089285714,"of, to, which, from, bat"
50222,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.089285714,"the, of, in, with, sars-cov-2"
50223,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.089285714,"the, have, been, of, any"
50224,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.089285714,"of, to, the, that, been"
50225,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.089285714,"in, the, of, and, to, follow, for, would, virus, such"
50226,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.089285714,"have, the, a, of, and"
50227,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.089285714,"the, is, that, virus, a"
50228,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.089285714,"of, and, the, viruses, bat"
50229,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.089285714,"it, found, the, to, that"
50230,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.089285714,"of, natural, the, and, viruses"
50231,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.089285714,"to, the, that, ratg13, and"
50232,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.089285714,"or, with, of, transmission, and"
50233,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.089285714,"to, and, of, that, including"
50234,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.089285714,"the, of, any, have, been"
50235,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.089285714,"are, viruses, the, and, bats"
50236,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.089285714,"that, bats, and, are, for"
50237,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.089285714,"for, the, possibility, as, of"
50238,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.089285714,"to, sars-cov-2, the, for, of"
50239,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.089285714,"the, of, sars-cov-2, as, for"
50240,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.089285714,"the, and, bats, most, by"
50241,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.089285714,"that, from, the, animals, for"
50242,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.089285714,"the, to, species, for, and"
50243,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.089285714,"that, the, to, as, intermediate"
50244,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.089285714,"the, in, was, is, to"
50245,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.089285714,"is, highly, the, at, from"
50246,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.089285714,"in, which, is, the, to"
50247,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.089285714,"and, coronaviruses, species, to, which"
50248,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.089285714,"coronaviruses, which, to, of, and"
50249,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.089285714,"to, other, and, the, in"
50250,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.089285714,"sars-cov-2, of, in, the, that"
50251,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.089285714,"the, of, in, protein, that"
50252,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.089285714,"to, the, of, and, that"
50253,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.089285714,"to, that, of, sars-cov-2, and"
50254,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","civet cats and raccoon dogs  

are the intermediate hosts",0.089285714,"the, raccoon, dogs, and, intermediate"
50255,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.089285714,"to, the, for, and, a, in, from, that, coronaviruses, humans"
50256,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.089285714,"the, in, to, that, was"
50257,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.089285714,"the, in, that, are, for"
50258,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.089285714,"the, has, of, to, from"
50259,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.089285714,"of, evidence, the, is, from"
50260,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.089285714,"that, and, identified, at, on"
50261,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.089285714,"that, sars-cov-2, to, and, on"
50262,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.089285714,"sars-cov-2, to, bat, could, reservoir"
50263,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.089285714,"studies, as, to, sars-cov-2, in"
50264,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.089285714,"a, bat, sars-cov-2, in, china"
50265,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.089285714,"sars-cov-2, and, likely, been, from"
50266,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.089285714,"the, sars-cov-2, to, a, of"
50267,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.089285714,"evidence, that, the, natural, of"
50268,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.089285714,"of, and, that, the, from"
50269,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.089285714,"of, bats, and, pangolins, sars-cov-2"
50270,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.089285714,"and, to, the, be, of"
50271,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.089285714,"with, the, of, humans, that"
50272,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.089285714,"the, clustering, that, sars-cov-2, and"
50273,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.089285714,"that, are, the, two, in"
50274,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.089285714,"and, a, the, of, with"
50275,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.089285714,"the, of, and, in, 2019"
50276,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.089285714,"the, of, at, market, taken"
50277,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.089285714,"the, of, at, a, et"
50278,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.089285714,"coronavirus, and, from, in, been"
50279,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.089285714,"that, the, sars-cov-2, and, mers-cov"
50280,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.089285714,"that, the, sars-cov-2, and, at"
50281,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.089285714,"in, of, to, sars-cov-2, and"
50282,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.089285714,"at, and, in, from, to"
50283,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.089285714,"and, of, sars-cov-2, in, to"
50284,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.089285714,"the, was, that, to, and"
50285,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.089285714,"cases, the, of, that, to"
50286,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.089285714,"the, of, cases, and, to"
50287,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.089285714,"the, of, in, from, market"
50288,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.089285714,"of, the, cases, to, that"
50289,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.089285714,"of, cases, in, the, early"
50290,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.089285714,"to, the, a, in, of, from, that, have, humans, contained"
50291,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.089285714,"have, a, of, in, the"
50292,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.089285714,"although, the, to, in, of"
50293,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.089285714,"that, sars-cov-2, are, in, an"
50294,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.089285714,"in, and, that, sars-cov-2, viruses"
50295,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.089285714,"that, sars-cov-2, and, is, viruses"
50296,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.089285714,"of, for, to, such, virus, would, follow, in, and, the"
50297,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.089285714,"the, be, of, are, to, such, as, and, in, other"
50298,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.089285714,"a, that, the, from, in"
50299,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.089285714,"a, to, events, in, the"
50300,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.089285714,"the, open, to, that, of"
50301,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.089285714,"that, sars-cov-2, a, to, an"
50302,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.089285714,"of, at, the, market, taken"
50303,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.089285714,"all, have, that, of, to"
50304,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.089285714,"the, animals, of, that, for, at, market, to, infected, evidence"
50305,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.089285714,"the, evidence, that, to, animals"
50306,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.089285714,"of, that, to, the, for"
50307,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.089285714,"also, and, the, from, animals"
50308,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.089285714,"have, to, of, all, that"
50309,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.089285714,"in, and, that, have, infect"
50310,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.089285714,"the, of, in, and, natural"
50311,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.089285714,"the, and, to, a, bat"
50312,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.089285714,"and, a, to, the, coronavirus"
50313,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.089285714,"the, of, that, been, to"
50314,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.089285714,"to, the, in, that, or"
50315,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.089285714,"early, cases, in, the, of"
50316,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.089285714,"of, the, cases, to, and"
50317,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.089285714,"of, other, such, as, and"
50318,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.089285714,"is, that, from, the, virus"
50319,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.089285714,"was, that, the, as, a"
50320,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.089285714,"the, has, to, from, of"
50321,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.089285714,"the, of, horseshoe, (rhinolophus, and"
50322,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.089285714,"the, from, and, with, of, a, which, to, that, virus"
50323,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.089285714,"and, a, to, the, of"
50324,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.089285714,"is, to, the, which, that"
50325,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.089285714,"bats, the, was, to, and"
50326,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.089285714,"to, genetic, is, which, the"
50327,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.089285714,"of, to, which, was, in"
50328,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.089285714,"and, to, bats, may, be"
50329,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.089285714,"is, and, (or, to, the"
50330,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.089285714,"the, possibility, of, as, for"
50331,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.089285714,"it, is, a, of, the"
50332,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.089285714,"and, a, on, the, of"
50333,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.089285714,"is, the, bat, sequence, of"
50334,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.089285714,"sars-cov-2, could, reservoir, to, bat"
50335,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.089285714,"a, that, was, the, as"
50336,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.089285714,"the, that, a, of, it"
50337,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.089285714,"the, seafood, market, of, a"
50338,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.089285714,"live, a, in, the, that"
50339,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.089285714,"have, in, the, with, or"
50340,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.089285714,"the, of, that, a, with"
50341,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.089285714,"that, be, hosts, for, the"
50342,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.089285714,"that, the, of, with, a"
50343,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.089285714,"ace2, and, by, the, was"
50344,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.089285714,"and, by, a, the, same"
50345,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.089285714,"to, and, it, is, that"
50346,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.089285714,"of, genome, similar, to, sars-cov-2."
50347,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.089285714,"the, rbd, could, be, to"
50348,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.089285714,"bats, the, for, of, which"
50349,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.089285714,"with, the, and, for, of, or, to, involved, be, at"
50350,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.089285714,"bats, or, be, the, for"
50351,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.089285714,"the, sars-cov-2, that, and, mers-cov"
50352,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.089285714,"the, sequence, similarity, with, sars-cov-2"
50353,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.089285714,"the, of, as, viral, and"
50354,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.089285714,"of, and, bat, between, the"
50355,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.089285714,"on, of, that, most, likely"
50356,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.089285714,"of, by, that, data, have"
50357,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.089285714,"that, of, bats, and, have"
50358,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.089285714,"to, from, a, the, it"
50359,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.089285714,"the, bat, coronaviruses, are, to"
50360,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.089285714,"from, bat, to, bats, are"
50361,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.089285714,"the, to, bat, coronaviruses, are"
50362,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.089285714,"and, may, to, the, in"
50363,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.089285714,"sars-cov-2, from, the, and, that"
50364,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.089285714,"the, of, virus, with, and"
50365,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.089285714,"the, covid-19, of, virus, genome"
50366,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.089285714,"other, with, the, bat, and"
50367,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.089285714,"was, the, ace2, and, by"
50368,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.089285714,"the, that, viruses, and, to"
50369,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.089285714,"of, coronaviruses, as, mers-cov,, or"
50370,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.089285714,"to, the, reservoirs, and, of"
50371,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.089285714,"the, to, a, with, as, and, could, human, of, coronavirus"
50372,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.089285714,"the, of, indicated, that, to"
50373,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.089285714,"that, the, is, to, of"
50374,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.089285714,"of, sars-, coronavirus, with, the"
50375,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.089285714,"the, and, has, bat, of"
50376,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.089285714,"the, genome, that, and, from"
50377,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.089285714,"that, related, to, and, from"
50378,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.089285714,"amino, acid, identity, with, in"
50379,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.089285714,"the, genome, that, from, and"
50380,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.089285714,"the, of, infected, hosts, and"
50381,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.089285714,"that, identified, on, and, at"
50382,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.089285714,"that, the, of, to, open"
50383,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.089285714,"revealed, of, sars-cov-2, from, the"
50384,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.089285714,"the, has, in, with, of"
50385,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.089285714,"sars-cov-2, has, the, virus, of"
50386,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.089285714,"on, that, most, likely, of"
50387,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.089285714,"in, from, of, were, the"
50388,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.089285714,"s, protein, the, sequence, of"
50389,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.089285714,"these, a, of, in, the"
50390,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.089285714,"the, sars-cov-2, and, a, of"
50391,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.089285714,"that, the, of, and, two"
50392,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.089285714,"to, are, coronaviruses, bat, the"
50393,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.089285714,"s, the, bat, and, sequence"
50394,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.089285714,"be, to, bats, of, are"
50395,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.089285714,"animals, from, that, for, the"
50396,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.089285714,"revealed, sars-cov-2, the, of, from"
50397,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.089285714,"coronaviruses, species, which, to, and"
50398,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.089285714,"sequence, that, and, sars-cov-2, is"
50399,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.089285714,"in, a, to, coronaviruses, from, bats, which, coronavirus, bat, and"
50400,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.089285714,"of, a, at, the, et"
50401,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.089285714,"a, acid, the, sars-cov-2, ace2"
50402,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.089285714,"of, revealed, that, the, and"
50403,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.089285714,"that, the, sars-cov-2, comparative, studies"
50404,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.089285714,"the, of, to, that, which"
50405,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.089285714,"sequence, with, the, sars-cov-2, similarity"
50406,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.089285714,"the, similarity, sars-cov-2, which, a"
50407,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.089285714,"it, a, and, to, the"
50408,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.089285714,"and, to, closely, related, are"
50409,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.089285714,"a, of, the, that, these"
50410,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.089285714,"the, of, and, in, western"
50411,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.089285714,"and, in, at, the, market."
50412,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.089285714,"sars-cov-2, a, of, the, that"
50413,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.089285714,"of, the, bat, a, from"
50414,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.089285714,"the, of, be, that, an"
50415,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.089285714,"the, of, that, was, and"
50416,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.089285714,"coronaviruses, mers-cov,, of, or, as"
50417,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.089285714,"that, the, virus, in, to"
50418,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.089285714,"the, of, a, and, these"
50419,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.089285714,"viruses, of, the, have, and"
50420,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.089285714,"the, of, have, to, as"
50421,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.089285714,"in, the, of, and, western"
50422,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.089285714,"that, to, are, hosts, for"
50423,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.089285714,"and, to, the, reservoirs, of"
50424,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.089285714,"from, a, its, the, it"
50425,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.089285714,"two, of, covs, genome, and"
50426,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.089285714,"that, and, may, for, sars-cov-2, to, the, between, in, with"
50427,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.089285714,"may, a, of, the, as"
50428,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.089285714,"sars-cov-2, of, that, the, or"
50429,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.089285714,"of, the, virus, and, with"
50430,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.089285714,"bats, of, species, to, the"
50431,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.089285714,"of, and, the, from, in"
50432,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.089285714,"of, the, in, with, sars-cov-2"
50433,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.089285714,"the, with, in, were, of"
50434,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.089285714,"the, nucleotide, and, in, from"
50435,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.089285714,"sars-cov-2, the, of, genome, from"
50436,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.089285714,"to, that, the, is, sars-cov-2"
50437,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.089285714,"sars-cov-2, is, sequence, and, that"
50438,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.089285714,"the, sars-cov-2, also, and, to"
50439,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.089285714,"the, sars-cov-2, and, et, to"
50440,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.089285714,"in, the, of, from, were"
50441,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.089285714,"the, and, bat, s, sequence"
50442,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.089285714,"sequence, the, s, protein, of"
50443,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.089285714,"sars-cov-2, the, rbd, protein, of"
50444,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.089285714,"bats, and, the, most, by"
50445,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.089285714,"at, from, in, and, to"
50446,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.089285714,"the, nucleotide, from, and, in"
50447,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.089285714,"at, and, in, the, to"
50448,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.089285714,"to, the, most, and, is"
50449,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.089285714,"is, to, in, the, ratg13"
50450,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.089285714,"ace2, in, a, the, for"
50451,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.089285714,"for, to, the, amino, in"
50452,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.089285714,"in, the, to, use, ("
50453,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.089285714,"that, the, of, sars-cov-2, or"
50454,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.089285714,"a, in, the, ace2, for"
50455,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.089285714,"that, sars-cov-2, a, in, intermediate"
50456,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.089285714,"the, for, that, be, hosts"
50457,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.089285714,"between, sars-cov-2, and, the, to, in, with, that, for, may"
50458,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.089285714,"to, amino, in, the, for"
50459,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.089285714,"the, to, that, hosts, for"
50460,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.089285714,"the, than, to, and, in"
50461,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.089285714,"that, sars-cov-2, to, in, intermediate"
50462,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.089285714,"the, rbd, to, that, sars-cov-2"
50463,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.089285714,"found, that, the, to, it"
50464,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.089285714,"that, have, in, infect, and"
50465,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.089285714,"to, in, the, use, ("
50466,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.089285714,"however,, the, to, suggesting, that"
50467,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.089285714,"in, the, and, a, sars-cov-2"
50468,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.089285714,"to, sars-cov-2, in, the, that"
50469,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.089285714,"to, that, the, and, sars-cov-2"
50470,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.089285714,"the, to, be, rbd, could"
50471,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.089285714,"the, acid, sars-cov-2, ace2, a"
50472,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.089285714,"to, for, and, the, species"
50473,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.089285714,"between, sars-cov-2, and, the, of"
50474,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.089285714,"to, of, the, and, was"
50475,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.089285714,"of, evidence, that, the, a"
50476,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.089285714,"to, with, the, of, human"
50477,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.089285714,"the, covid-19, of, to, with"
50478,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.089285714,"in, to, of, the, covid-19"
50479,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.089285714,"in, the, and, at, market."
50480,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.089285714,"in, the, market, from, of"
50481,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.089285714,"that, the, of, in, for"
50482,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.089285714,"coronaviruses, of, a, in, bats"
50483,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.089285714,"a, from, to, the, it"
50484,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.089285714,"bats, the, which, of, for"
50485,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.089285714,"is, highly, at, the, from"
50486,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.089285714,"that, from, the, at, of"
50487,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.089285714,"of, the, genome, covid-19, virus"
50488,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.089285714,"the, of, from, sars-cov-2, genome"
50489,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.089285714,"the, is, it, even, of"
50490,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.089285714,"a, of, the, or, in"
50491,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.089285714,"the, in, or, a, of"
50492,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.089285714,"the, of, and, horseshoe, (rhinolophus"
50493,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.089285714,"the, of, most, likely, or"
50494,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.089285714,"of, one, and, are, the"
50495,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.089285714,"sars-cov-2, in, and, that, the"
50496,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.089285714,"the, of, in, and, to"
50497,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.089285714,"of, and, the, to, species"
50498,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.089285714,"a, the, same, and, by"
50499,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.089285714,"the, between, and, of, bat"
50500,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.089285714,"this, in, the, of, similar"
50501,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.089285714,"the, region, a, in, this"
50502,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.089285714,"in, of, and, china,, similar"
50503,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.089285714,"to, recombination, the, of, a"
50504,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.089285714,"to, is, the, which, genetic"
50505,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.089285714,"by, similar, to, the, sars-cov-2"
50506,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.089285714,"the, to, a, and, it"
50507,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.089285714,"genome, with, and, sars-cov-2, a"
50508,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.089285714,"the, at, sars-cov-2, a, in"
50509,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.089285714,"the, and, it, with, to"
50510,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.089285714,"that, of, to, with, the"
50511,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.089285714,"the, of, that, human, to"
50512,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.089285714,"of, have, the, to, through"
50513,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.089285714,"to, that, in, respiratory, human"
50514,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.089285714,"the, in, a, to, events"
50515,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.089285714,"to, sars-cov-2, a, and, the"
50516,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.089285714,"the, and, other, with, bat"
50517,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.089285714,"of, cases, with, during, had, a, to, early, the, in"
50518,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.089285714,"to, for, the, of, evidence, infected, animals, at, market, that"
50519,"civet cats and raccoon dogs  

are the intermediate hosts","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.089285714,"and, raccoon, dogs, the, intermediate"
50520,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.089285714,"in, the, a, that, coronaviruses, from, to, humans, and, for"
50521,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.089285714,"from, in, humans, contained, the, of, that, a, have, to"
50522,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.089285714,"that, bats, the, of, and, viruses, in, southern, china, for"
50523,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.089285714,"a, and, coronaviruses, from, bat, to, which, coronavirus, in, bats"
50524,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.089285714,"and, a, to, the, coronavirus, could, of, human, with, as"
50525,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.089285714,"the, as, a, of, that, from, to, by, bat, and"
50526,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.089285714,"results, of, the, in, and, that, a, group, with, viruses"
50527,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.089285714,"found, that, genome, similar, to, and, a, on, the, of"
50528,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.089285714,"in, viruses, are, and, together, with, that, the, sars, is"
50529,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.089285714,"had, a, the, with, early, cases, of, in, during, to"
50530,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.089285714,"the, to, be, involved, at, or, with, of, for, and"
50531,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.089285714,"in, the, of, to, which"
50532,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.089285714,"a, of, the, is, to"
50533,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.089285714,"the, seafood, market, a, of"
50534,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.089285714,"is, a, the, covid-19, of"
50535,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.089285714,"that, the, in, live, a"
50536,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.089285714,"of, sequences, at, the, in"
50537,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.089285714,"is, a, on, the, its"
50538,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.089285714,"to, on, the, that, for"
50539,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.089285714,"that, from, to, and, related"
50540,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.089285714,"that, sars-cov-2, the, in, with"
50541,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.089285714,"the, most, likely, or, of"
50542,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.089285714,"several, of, have, the, one"
50543,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.089285714,"that, hosts, for, to, the"
50544,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.089285714,"the, that, is, which, to"
50545,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.089285714,"the, a, it, its, from"
50546,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.089285714,"to, it, is, that, in"
50547,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.089285714,"protein, the, of, rbd, sars-cov-2"
50548,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.089285714,"the, of, shows, that, natural"
50549,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.089285714,"the, shows, that, of, natural"
50550,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.089285714,"a, of, the, by, that"
50551,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.089285714,"a, the, of, is, it"
50552,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.089285714,"the, not, that, in, of"
50553,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.089285714,"coronavirus, and, in, been, from"
50554,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.089285714,"the, to, a, that, not"
50555,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.089285714,"bat, that, the, of, analysis"
50556,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.089285714,"this, region, a, in, the"
50557,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.089285714,"of, the, indicated, that, to"
50558,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.089285714,"and, to, than, the, in"
50559,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.089285714,"to, the, evidence, animals, that"
50560,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.089285714,"the, from, evidence, of, is"
50561,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.089285714,"the, from, of, a, bat"
50562,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.089285714,"the, from, that, a, bat"
50563,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.089285714,"of, these, a, from, bat"
50564,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.089285714,"viruses, have, of, these, a"
50565,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.089285714,"of, the, in, to, that"
50566,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.089285714,"be, and, zoonotic, to, in"
50567,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.089285714,"in, to, be, the, is"
50568,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.089285714,"to, for, the, of, that"
50569,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.089285714,"revealed, that, the, of, and"
50570,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.089285714,"these, viruses, have, a, of"
50571,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.089285714,"the, of, covid-19, in, china"
50572,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.089285714,"of, been, that, the, a"
50573,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.089285714,"evidence, the, that, of, natural"
50574,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.089285714,"in, that, the, two, are"
50575,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.089285714,"of, the, that, and, two"
50576,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.089285714,"the, of, viruses, in, that, bats, and, for, southern, china"
50577,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.089285714,"in, the, virus, that, with"
50578,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.089285714,"the, in, of, covid-19, china"
50579,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.089285714,"has, with, the, of, in"
50580,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.089285714,"the, in, not, that, of"
50581,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.089285714,"in, of, to, with, that"
50582,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.089285714,"in, the, of, a, have"
50583,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.089285714,"in, the, of, a, these"
50584,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.089285714,"the, viruses, and, of, bat"
50585,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.089285714,"in, the, host, bat, or"
50586,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.089285714,"the, and, even, sites, of"
50587,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.089285714,"from, to, are, bat, bats"
50588,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.089285714,"bats, are, to, be, of"
50589,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.089285714,"recently, in, bats, are, to"
50590,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.089285714,"as, in, the, of, and, are, to, other, be, such"
50591,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.089285714,"and, bats, may, be, to"
50592,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.089285714,"have, the, of, and, viruses"
50593,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.089285714,"the, virus, a, of, which, to, with, that, from, and"
50594,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.089285714,"from, the, and, animals, also"
50595,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.089285714,"have, through, the, of, to"
50596,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.089285714,"one, of, the, several, have"
50597,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.089285714,"hosts, and, infected, the, of"
50598,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.089285714,"from, the, to, a, that, bat, as, and, by, of"
50599,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.089285714,"a, with, and, sars-cov-2, genome"
50600,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.089285714,"identity, in, amino, acid, with"
50601,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.089285714,"bats, the, is, and, in"
50602,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.089285714,"other, such, as, of, and"
50603,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.089285714,"data, have, that, by, of"
50604,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.089285714,"that, a, sars-cov-2, to, an"
50605,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.089285714,"sars-cov-2, in, a, that, intermediate"
50606,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.089285714,"that, intermediate, sars-cov-2, to, in"
50607,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.089285714,"sars-cov-2, is, a, to, that"
50608,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.089285714,"the, of, with, that, humans"
50609,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.089285714,"the, of, is, or, that"
50610,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.089285714,"of, that, the, is, or"
50611,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.089285714,"sars-cov-2, to, as, studies, in"
50612,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.089285714,"the, been, of, that, a"
50613,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.089285714,"the, to, sars-cov-2, bat, cov"
50614,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.089285714,"found, to, be, the, sars-cov-2"
50615,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.089285714,"are, that, the, of, sars-cov-2"
50616,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.089285714,"of, the, that, sars-cov-2, with"
50617,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.089285714,"the, that, are, for, sars-cov-2"
50618,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.089285714,"the, of, viral, as, and"
50619,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.089285714,"the, of, and, as, a"
50620,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.089285714,"evidence, the, of, have, to"
50621,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.089285714,"is, a, its, on, the"
50622,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.089285714,"is, bat, pangolin, the, in"
50623,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.089285714,"in, the, is, pangolin, which"
50624,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.089285714,"of, sars-cov-2, that, and, to"
50625,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.089285714,"recently, bats, are, in, to"
50626,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.089285714,"that, bats, are, sars-cov-2, to"
50627,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.089285714,"the, to, ratg13, and, that"
50628,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.089285714,"this, ratg13, is, the, that"
50629,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.089285714,"be, the, that, from, but"
50630,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.089285714,"a, by, sequences, the, in"
50631,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.089285714,"the, and, is, most, to"
50632,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.089285714,"bats, the, be, or, for"
50633,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.089285714,"comparative, studies, that, the, sars-cov-2"
50634,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.089285714,"to, the, and, from, bat"
50635,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.089285714,"the, and, clustering, that, sars-cov-2"
50636,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.089285714,"that, the, bat, a, from"
50637,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.089285714,"bats, are, for, and, that"
50638,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.089285714,"bats, are, to, that, sars-cov-2"
50639,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.089285714,"the, of, that, a, to"
50640,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.089285714,"sars-cov-2, a, in, bat, china"
50641,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.089285714,"the, of, sequences, in, at"
50642,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.089285714,"the, by, a, sequences, in"
50643,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.089285714,"to, of, which, from, bat"
50644,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.089285714,"in, to, of, which, was"
50645,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.089285714,"of, bat, a, from, these"
50646,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.089285714,"a, of, one, to, ratg13,"
50647,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.089285714,"genome, of, similar, to, sars-cov-2."
50648,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.089285714,"of, genome, two, covs, and"
50649,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.089285714,"of, and, china,, similar, in"
50650,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.089285714,"are, that, an, sars-cov-2, in"
50651,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.089285714,"to, that, are, hosts, for"
50652,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.089285714,"the, are, one, of, and"
50653,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.089285714,"to, by, similar, sars-cov-2, the"
50654,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.089285714,"one, of, to, a, ratg13,"
50655,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.089285714,"the, that, protein, in, of"
50656,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.089285714,"that, sars-cov-2, and, viruses, in"
50657,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.089285714,"a, the, of, and, with"
50658,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.089285714,"in, the, group, of, results, a, with, viruses, and, that"
50659,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.089285714,"sars-cov-2, in, the, that, of"
50660,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.089285714,"of, the, we, that, sars-cov-2"
50661,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.089285714,"that, the, of, is, sars-cov-2"
50662,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.089285714,"bats, are, the, and, viruses"
50663,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.089285714,"in, that, the, be, and"
50664,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.089285714,"that, on, to, the, for"
50665,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.089285714,"is, the, that, ratg13, this"
50666,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.089285714,"cluster, for, sars-cov-2, with, that"
50667,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.089285714,"sars-cov-2, been, from, likely, and"
50668,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.089285714,"to, the, and, is, (or"
50669,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.089285714,"is, the, bat, in, pangolin"
50670,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.089285714,"the, are, in, viruses, together, with, is, sars, that, and"
50671,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.089285714,"the, with, in, have, or"
50672,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.089285714,"the, in, is, to, ratg13"
50673,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.089285714,"host, or, the, in, bat"
50674,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.089285714,"in, the, that, are, for"
50675,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.089285714,"the, that, are, sars-cov-2, for"
50676,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.089285714,"bats, are, the, of, that"
50677,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.089285714,"the, that, also, sars-cov-2, is"
50678,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.089285714,"of, sars-cov-2, and, bats, pangolins"
50679,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.089285714,"and, have, that, bats, of"
50680,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.089285714,"on, and, of, in, the"
50681,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.089285714,"that, sars-cov-2, on, and, to"
50682,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.089285714,"a, the, on, of, and"
50683,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.089285714,"the, of, a, to, on, found, genome, similar, and, that"
50684,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.089285714,"the, of, in, and, that"
50685,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.089285714,"the, and, have, a, of"
50686,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.089285714,"the, in, of, and, that"
50687,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.089285714,"that, sars-cov-2, to, the, rbd"
50688,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.089285714,"is, which, the, in, pangolin"
50689,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.089285714,"has, sars-cov-2, the, of, virus"
50690,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.089285714,"we, sars-cov-2, the, that, of"
50691,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.089285714,"the, of, recombination, a, to"
50692,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.089285714,"sars-cov-2, be, the, and, virus"
50693,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.089285714,"that, the, in, a, of"
50694,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.089285714,"in, a, sars-cov-2, at, the"
50695,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.089285714,"a, sars-cov-2, the, from, in"
50696,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.089285714,"the, that, from, but, be"
50697,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.089285714,"it, is, even, the, of"
50698,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.089285714,"it, with, and, to, the"
50699,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.089285714,"even, of, and, the, sites"
50700,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.089285714,"to, that, in, with, of"
50701,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.089285714,"cluster, with, sars-cov-2, that, for"
50702,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.089285714,"to, that, in, human, respiratory"
50703,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.089285714,"the, of, that, in, to"
50704,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.089285714,"that, the, at, of, to"
50705,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.089285714,"in, although, the, of, to"
50706,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.089285714,"the, of, bat, is, sequence"
50707,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.089285714,"of, to, that, and, including"
50708,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.089285714,"it, that, and, to, is"
50709,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.089285714,"is, to, in, that, it"
50710,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.089285714,"as, intermediate, that, to, the"
50711,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.089285714,"have, the, of, to, as"
50712,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.089285714,"have, to, the, evidence, of"
50713,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.089285714,"zoonotic, in, and, be, to"
50714,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.089285714,"sars-cov-2, be, virus, the, and"
50715,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.089108911,"the, in, a, of, group, large, that, bats, and"
50716,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.089108911,"infected, for, virus, or, were, one, of, and, bats,"
50717,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.089108911,"the, that, to, have, of, it, would, sars-cov-2, any"
50718,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.089108911,"sars-cov-2, of, the, and, to, in, virus, ability, ace2"
50719,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.089108911,"for, and, an, with, to, the, in, of, a"
50720,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.089108911,"the, from, by, of, a, et, al., at, virus"
50721,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.089108911,"natural, of, at, the, a, to, that, such, animal"
50722,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.089108911,"sars-cov-2, the, of, any, that, have, to, it, would"
50723,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.089108911,"a, of, market, in, that, by, the, or, to"
50724,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.089108911,"the, of, a, in, to, that, with, and, were"
50725,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.089108911,"and, the, of, to, as, that, can, result, is"
50726,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.089108911,"that, in, the, a, or, and, of, animal, may"
50727,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.089108911,"as, and, the, of, to, can, that, is, result"
50728,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.089108911,"that, the, of, market, in, to, or, a, by"
50729,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.089108911,"reported, that, the, to, suggesting, by, with, in, of"
50730,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.089108911,"coronaviruses, that, were, to, found, in, bats, and, from"
50731,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.089108911,"analysis, that, the, in, bats, and, to, humans, of"
50732,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.089108911,"one, of, bats,, and, for, virus, were, infected, or"
50733,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.089108911,"by, a, of, virus, one, to, and, the, for"
50734,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.089108911,"may, in, a, of, animal, and, that, the, or"
50735,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.089108911,"a, large, of, and, that, the, in, group, bats"
50736,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.089108911,"and, a, of, in, is, the, for, viruses, to"
50737,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.089108911,"a, for, the, of, and, in, with, to, an"
50738,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.089108911,"to, bats, were, and, in, from, that, coronaviruses, found"
50739,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.089108911,"to, the, bats, and, in, of, analysis, that, humans"
50740,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.089108911,"of, a, virus, at, the, by, et, al., from"
50741,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.089108911,"of, in, that, with, by, the, reported, suggesting, to"
50742,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.089108911,"the, to, in, a, for, of, viruses, is, and"
50743,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.089108911,"to, a, for, the, virus, by, one, of, and"
50744,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.089108911,"that, to, such, at, the, animal, a, of, natural"
50745,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.089108911,"sars-cov-2, of, to, ace2, virus, in, and, ability, the"
50746,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.088888889,"that, or, a, in"
50747,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.088888889,"a, large, group, of"
50748,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.088888889,"a, bat, and, to"
50749,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.088888889,"., are, a, coronaviruses"
50750,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.088888889,"to, a, human, bat"
50751,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.088888889,"viruses, to, sars-cov-2, coronaviruses"
50752,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.088888889,"to, which, a, sars-cov-2"
50753,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.088888889,"a, sars-cov-2, in, bat"
50754,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.088888889,"related, to, which, a"
50755,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.088888889,"the, into, of, and"
50756,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.088888889,"are, in, but, of"
50757,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.088888889,"of, a, animal, species"
50758,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.088888889,"most, of, the, have"
50759,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.088888889,"of, that, bats, for"
50760,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.088888889,"study, of, with, bats"
50761,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.088888889,"that, bats, and, for"
50762,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.088888889,"have, similar, to, and"
50763,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","identified numerous human–animal interactions that con- 

stitute emergence risk factors, for example bat tourism, wet 

markets, wildlife supply chains for human consumption,15 land 

management practices, and environmental perturbations.",0.088888889,"that, bat, and, for"
50764,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.088888889,"of, sars-cov-2, to, and"
50765,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.088888889,"of, and, more, sars-cov-2"
50766,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.088888889,"sars-cov-2, bats, more, than"
50767,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.088888889,"to, sars-cov-2, bats, of"
50768,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.088888889,"in, is, to, sars-cov-2"
50769,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.088888889,"in, is, one, to"
50770,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.088888889,"is, sars-cov-2, virus, genome"
50771,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.088888889,"sars-cov-2, in, is, to"
50772,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.088888889,"a, coronavirus, and, for"
50773,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.088888889,"a, for, is, and"
50774,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.088888889,"the, of, in, same"
50775,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.088888889,"the, spillover, from, to"
50776,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.088888889,"is, sars-cov-2, a, in"
50777,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.088888889,"sars-cov-2, been, of, be"
50778,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.088888889,"from, to, would, the"
50779,Genetic evidence suggesting otherwise is yet to be presented.,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.088888889,"genetic, is, to, be"
50780,"Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.088888889,"also, from, the, unlikely"
50781,"Those who eagerly peddle suggestions of 

laboratory involvement have consistently failed to present 

credible arguments to support their positions.","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.088888889,"those, of, laboratory, to"
50782,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.088888889,"the, of, other, to"
50783,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.088888889,"that, with, a, and"
50784,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.088888889,"is, sars-cov-2, that, virus"
50785,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.088888889,"all, that, human, and"
50786,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.088888889,"the, identified, sars-cov-2, to"
50787,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.088888889,"to, genome, coronavirus,, bat"
50788,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.088888889,"t, that, the, of"
50789,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.088888889,"the, and, natural, reservoir"
50790,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.088888889,"a, of, the, viruses"
50791,"Scientific reports published so far include  

hosts, such as bats (28), pangolins (29), cats  

(11), and dogs (30)","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.088888889,"hosts,, such, as, and"
50792,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.088888889,"of, in, that, which"
50793,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.088888889,"the, known, of, and"
50794,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.088888889,"the, known, to, in, is, of, and, sars-cov-2"
50795,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.088888889,"has, that, human, a"
50796,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.088888889,"the, known, and, of"
50797,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.088888889,"and, that, the, was"
50798,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.088888889,"to, sars-cov-2, bats, from"
50799,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.088888889,"intermediate, bats, humans, the"
50800,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.088888889,"as, to, sars-cov-2, humans"
50801,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.088888889,"been, in, of, as"
50802,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.088888889,"the, of, zoonotic, market"
50803,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.088888889,"the, and, to, a"
50804,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.088888889,"of, and, a, the"
50805,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.088888889,"been, by, and, the"
50806,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.088888889,"the, intermediate, to, as"
50807,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.088888889,"the, cause, to, from"
50808,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.088888889,"the, that, from, virus"
50809,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.088888889,"for, and, that, the"
50810,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.088888889,"the, with, sars-cov-2, at"
50811,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.088888889,"the, of, sars-cov-2, through"
50812,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.088888889,"is, the, wuhan, to"
50813,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.088888889,"to, highly, was, the"
50814,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.088888889,"the, to, was, from"
50815,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.088888889,"the, coronavirus, is, to"
50816,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.088888889,"is, bats,, sars-cov-2, to"
50817,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.088888889,"and, of, the, into"
50818,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.088888889,"the, of, coronaviruses, and"
50819,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.088888889,"to, the, of, sars-cov-2,"
50820,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.088888889,"to, the, and, sars-cov"
50821,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.088888889,"and, animals, to, in"
50822,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.088888889,"from, animals, through, in"
50823,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.088888889,"analysis, of, the, in"
50824,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.088888889,"in, of, sars-cov-2, that"
50825,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.088888889,"the, for, of, that"
50826,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.088888889,"the, of, natural, that"
50827,"bats are also important reservoir species for a great 

range of coronaviruses","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.088888889,"are, for, a, coronaviruses"
50828,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.088888889,"be, of, sars-cov-2, been"
50829,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.088888889,"identified, sars-cov-2, to, the"
50830,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.088888889,"the, of, through, to"
50831,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.088888889,"the, to, in, humans"
50832,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.088888889,"the, evidence, from, to"
50833,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.088888889,"sars-cov-2, are, animal, and"
50834,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.088888889,"the, result, of, from"
50835,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.088888889,"humans, that, the, sars-cov-2"
50836,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.088888889,"sars-cov-2, to, the, that"
50837,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.088888889,"from, the, origin, of"
50838,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.088888889,"sars-cov-2, from, of, as"
50839,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.088888889,"the, has, that, and"
50840,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.088888889,"the, that, and, has"
50841,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.088888889,"are, and, the, that"
50842,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.088888889,"that, natural, the, and"
50843,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.088888889,"the, that, and, was"
50844,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.088888889,"that, have, and, from"
50845,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.088888889,"the, have, from, and"
50846,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.088888889,"that, not, from, bat"
50847,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.088888889,"bats, of, sars-cov-2, and"
50848,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.088888889,"bats, and, closely, related"
50849,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.088888889,"in, the, by, and, that, sars-cov-2, of, are"
50850,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.088888889,"the, of, market, zoonotic"
50851,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.088888889,"the, sars-cov-2, from, of"
50852,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.088888889,"the, that, known, to, are, of, and, sars-cov-2"
50853,"The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.088888889,"the, that, early, with"
50854,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.088888889,"the, that, to, are, more, closely, related, in"
50855,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.088888889,"a, that, to, the"
50856,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.088888889,"in, the, to, that"
50857,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.088888889,"is, a, with, the"
50858,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.088888889,"he, by, at, the"
50859,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.088888889,"of, a, was, from"
50860,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.088888889,"been, in, other, of"
50861,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.088888889,"were, to, related, these"
50862,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.088888889,"the, reservoirs, more, in"
50863,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.088888889,"to, sampled, animal, in, the, were, introductions, other"
50864,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.088888889,"that, the, was, and"
50865,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.088888889,"the, in, huanan, market"
50866,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.088888889,"and, likely, an, animal"
50867,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.088888889,"a, in, and, animal"
50868,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.088888889,"of, to, and, in"
50869,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.088888889,"sars-cov-2, from, to, in"
50870,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.088888889,"of, to, sars-cov-2, from"
50871,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.088888889,"sars-cov-2, a, that, with"
50872,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.088888889,"the, evidence, of, natural"
50873,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.088888889,"that, were, to, and"
50874,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.088888889,"genetic, human, that, a, natural, of, the, is"
50875,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.088888889,"used, to, that, in"
50876,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.088888889,"a, that, or, in"
50877,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.088888889,"that, in, or, a"
50878,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.088888889,"there, a, in, sars-cov-2"
50879,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.088888889,"the, known, and, sars-cov-2, is, to, in, of"
50880,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.088888889,"the, that, are, known, to, sars-cov-2, and, of"
50881,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.088888889,"in, related, that, the, are, more, closely, to"
50882,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.088888889,"of, sars-cov-2, was, to, bats,, the, its, in"
50883,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.088888889,"sars-cov-2, at, the, with"
50884,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.088888889,"that, the, sars-cov-2, as"
50885,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.088888889,"that, in, animals, from"
50886,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.088888889,"the, genetic, to, in"
50887,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.088888889,"that, in, to, a"
50888,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.088888889,"in, is, that, covid-19"
50889,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.088888889,"is, a, that, to"
50890,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.088888889,"in, is, to, that"
50891,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.088888889,"and, to, bat, a"
50892,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.088888889,"has, that, and, the"
50893,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.088888889,"the, to, a, virus"
50894,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.088888889,"the, and, a, to"
50895,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.088888889,"the, that, virus, with"
50896,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.088888889,"to, the, with, bat"
50897,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.088888889,"the, and, with, to"
50898,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.088888889,"the, that, virus, this"
50899,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.088888889,"of, that, to, zoonotic"
50900,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.088888889,"to, a, all, animals,, zoonotic, of, and, species"
50901,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.088888889,"and, all, that, human"
50902,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.088888889,"and, that, have, from"
50903,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.088888889,"that, in, from, animals"
50904,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.088888889,"which, that, and, from"
50905,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.088888889,"from, and, which, in"
50906,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.088888889,"cov, that, and, human"
50907,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.088888889,"have, in, cov, which"
50908,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.088888889,"and, the, of, in"
50909,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.088888889,"is, to, from, and"
50910,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.088888889,"to, and, a, the"
50911,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.088888889,"as, intermediate, to, the"
50912,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.088888889,"the, as, to, of"
50913,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.088888889,"study, of, bats, with"
50914,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.088888889,"in, of, the, bats"
50915,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.088888889,"of, the, a, possible"
50916,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.088888889,"with, of, in, bats"
50917,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.088888889,"a, of, with, the"
50918,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.088888889,"with, and, a, that"
50919,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.088888889,"been, in, of, or"
50920,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.088888889,"the, of, by, with"
50921,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.088888889,"first, in, and, as"
50922,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.088888889,"that, which, and, from"
50923,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.088888889,"the, from, rna, that"
50924,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.088888889,"to, of, which, from"
50925,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.088888889,"virus, that, the, genome,"
50926,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.088888889,"that, from, to, an"
50927,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.088888889,"bats, a, virus, the"
50928,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.088888889,"bat, coronavirus, with, to"
50929,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.088888889,"for, and, with, from, to, the, of, a"
50930,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.088888889,"a, the, coronavirus, with"
50931,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.088888889,"a, the, from, pangolin"
50932,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.088888889,"the, coronavirus, from, bat"
50933,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.088888889,"to, be, of, and"
50934,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.088888889,"to, a, from, in, the, virus, china, and"
50935,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.088888889,"the, have, a, at"
50936,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.088888889,"the, have, in, that"
50937,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.088888889,"the, of, that, scientists"
50938,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.088888889,"the, is, in, of, to, and, but, covid-19"
50939,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.088888889,"that, has, been, to"
50940,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.088888889,"that, to, used, in"
50941,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.088888889,"has, been, that, to"
50942,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.088888889,"there, is, that, of"
50943,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.088888889,"virus, the, was, of"
50944,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.088888889,"the, to, humans, in"
50945,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.088888889,"with, the, bat, and"
50946,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.088888889,"the, natural, reservoir, and"
50947,"bats are also important reservoir species for a great 

range of coronaviruses","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.088888889,"reservoir, for, a, of"
50948,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.088888889,"have, been, in, the"
50949,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.088888889,"in, infected, may, common"
50950,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.088888889,"the, also, and, spread"
50951,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.088888889,"the, not, reported, in"
50952,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.088888889,"to, the, sars-cov-2, bats"
50953,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.088888889,"that, is, bats, bat"
50954,"Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.088888889,"of, live, in, wuhan"
50955,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.088888889,"it, that, of, a"
50956,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.088888889,"that, from, the, at"
50957,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.088888889,"the, that, from, market"
50958,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.088888889,"the, rna, that, from"
50959,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.088888889,"be, that, from, the"
50960,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.088888889,"the, at, that, for"
50961,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.088888889,"the, of, bats, be"
50962,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.088888889,"a, coronavirus, the, with"
50963,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.088888889,"coronavirus, the, with, not"
50964,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.088888889,"the, that, viruses, be"
50965,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.088888889,"the, of, with, but"
50966,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.088888889,"the, of, human, to"
50967,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.088888889,"to, the, has, been"
50968,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.088888889,"of, sars-cov-2, to, coronavirus"
50969,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.088888889,"that, the, to, ace2"
50970,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.088888889,"the, sars-cov-2, by, sars-cov"
50971,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.088888889,"to, the, coronavirus, is"
50972,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.088888889,"can, be, coronavirus, to"
50973,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.088888889,"of, bat, genome, than"
50974,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Scientific reports published so far include  

hosts, such as bats (28), pangolins (29), cats  

(11), and dogs (30)",0.088888889,"and, hosts,, such, as"
50975,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.088888889,"in, spillover, to, and"
50976,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.088888889,"human, and, mild, in"
50977,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.088888889,"human, covs, to, and"
50978,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.088888889,"of, the, bat, that"
50979,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.088888889,"is, to, have, the"
50980,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.088888889,"the, from, in, of"
50981,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.088888889,"the, are, of, in"
50982,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.088888889,"of, a, from, in"
50983,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.088888889,"that, is, bat, bats"
50984,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.088888889,"on, by, that, and"
50985,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.088888889,"and, on, that, of"
50986,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.088888889,"that, bats, and, of"
50987,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.088888889,"bats, and, caused, by"
50988,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",Many of these CoVs can infect several animal species as well,0.088888889,"of, animal, species, as"
50989,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.088888889,"a, to, that, animal"
50990,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.088888889,"the, a, spillover, to"
50991,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.088888889,"a, the, virus, from"
50992,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.088888889,"is, to, the, from"
50993,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.088888889,"the, to, humans, sars-cov-2"
50994,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.088888889,"from, sars-cov-2, isolated, all"
50995,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.088888889,"from, cause, to, the"
50996,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.088888889,"the, and, in, found"
50997,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.088888889,"in, and, are, the"
50998,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.088888889,"the, and, to, human"
50999,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.088888889,"the, to, in, from"
51000,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.088888889,"and, have, from, the"
51001,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.088888889,"the, to, in, infected, virus, animal, and, market"
51002,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.088888889,"the, and, market, to"
51003,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.088888889,"the, and, an, to"
51004,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.088888889,"sars-cov-2, and, the, from"
51005,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.088888889,"and, the, sars-cov-2, is"
51006,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.088888889,"to, bats,, sars-cov-2, is"
51007,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.088888889,"and, that, of, to"
51008,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.088888889,"to, and, of, that"
51009,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.088888889,"the, analysis, in, of"
51010,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.088888889,"analysis, of, the, virus"
51011,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.088888889,"the, in, pangolins,, coronavirus"
51012,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.088888889,"human, mild, in, and"
51013,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.088888889,"for, and, in, of"
51014,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.088888889,"the, sars-cov-2, sequence, coronaviruses"
51015,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.088888889,"on, and, that, by"
51016,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.088888889,"from, sars-cov-2, and, the"
51017,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.088888889,"to, human, in, or"
51018,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.088888889,"the, and, bat, that"
51019,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.088888889,"is, that, and, the"
51020,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.088888889,"at, and, the, that"
51021,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.088888889,"and, revealed, between, at"
51022,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.088888889,"the, at, that, is"
51023,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.088888889,"to, the, from, humans"
51024,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.088888889,"to, the, seafood, that"
51025,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.088888889,"the, in, to, that"
51026,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.088888889,"studies, a, in, the"
51027,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.088888889,"further, the, in, that"
51028,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.088888889,"is, the, and, infected"
51029,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.088888889,"patients, the, of, and"
51030,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.088888889,"the, of, is, which"
51031,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.088888889,"on, that, and, a"
51032,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.088888889,"are, the, that, to"
51033,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.088888889,"that, bat, in, a"
51034,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.088888889,"is, a, that, in"
51035,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.088888889,"two, and, a, the"
51036,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.088888889,"sars-cov-2, and, the, that"
51037,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.088888889,"genome, the, of, and"
51038,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.088888889,"sars-cov-2, animal, are, and"
51039,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.088888889,"no, that, of, the"
51040,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.088888889,"which, the, of, to, as, et, al., may"
51041,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.088888889,"the, in, with, at"
51042,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.088888889,"a, may, these, the"
51043,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.088888889,"host, of, the, may"
51044,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.088888889,"that, the, seafood, to"
51045,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.088888889,"the, that, of, community."
51046,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.088888889,"after, the, of, to"
51047,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.088888889,"a, sars-cov-2, the, of"
51048,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.088888889,"hypothesis, is, the, that"
51049,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.088888889,"have, the, is, to"
51050,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.088888889,"et, of, and, to"
51051,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.088888889,"ratg13,, the, of, to"
51052,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.088888889,"also, was, the, in"
51053,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.088888889,"in, the, bat, rmyn02,"
51054,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.088888889,"sars-cov-2, ace2, a, and"
51055,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.088888889,"and, potential, sars-cov-2, between"
51056,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.088888889,"of, the, that, community."
51057,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.088888889,"other, in, been, of"
51058,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.088888889,"of, in, been, or"
51059,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.088888889,"lineages, of, coronaviruses, as"
51060,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.088888889,"a, of, sars-cov-2, origin"
51061,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.088888889,"., are, coronaviruses, a"
51062,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.088888889,"a, virus, bats, the"
51063,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.088888889,"the, has, been, and"
51064,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.088888889,"in, a, of, zoonotic"
51065,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.088888889,"these, were, related, to"
51066,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.088888889,"sars-cov-2, to, a, similarity"
51067,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.088888889,"the, genetic, similarity, sars-cov-2"
51068,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.088888889,"a, in, the, it"
51069,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.088888889,"human, to, bat, a"
51070,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.088888889,"the, to, a, of"
51071,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.088888889,"sars-cov-2, to, coronaviruses, viruses"
51072,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.088888889,"is, the, to, wuhan"
51073,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.088888889,"been, and, the, by"
51074,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.088888889,"highly, the, to, was"
51075,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.088888889,"the, sars-cov-2, to, virus"
51076,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.088888889,"been, genome, and, sars-cov-2"
51077,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.088888889,"the, sars-cov-2, to, genome"
51078,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.088888889,"the, sars-cov-2, virus, been"
51079,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.088888889,"in, to, is, the"
51080,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.088888889,"that, to, the, sars-cov-2"
51081,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.088888889,"in, which, and, from"
51082,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.088888889,"the, from, in, and"
51083,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.088888889,"of, with, a, sars-cov-2"
51084,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.088888889,"bat, with, sars-cov-2, that"
51085,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.088888889,"found, that, with, of"
51086,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.088888889,"the, that, a, not"
51087,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.088888889,"that, pangolin-cov, the, of"
51088,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.088888889,"region, of, in, the"
51089,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.088888889,"to, of, ratg13, in"
51090,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","bats are also important reservoir species for a great 

range of coronaviruses",0.088888889,"a, coronaviruses, are, for"
51091,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","bats are also important reservoir species for a great 

range of coronaviruses",0.088888889,"a, for, reservoir, of"
51092,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","bats are also important reservoir species for a great 

range of coronaviruses",0.088888889,"a, of, also, are"
51093,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","bats are also important reservoir species for a great 

range of coronaviruses",0.088888889,"are, also, of, for"
51094,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","bats are also important reservoir species for a great 

range of coronaviruses",0.088888889,"of, bats, for, are"
51095,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.088888889,"the, sars-cov-2, and, from"
51096,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.088888889,"to, sars-cov-2, in, humans"
51097,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.088888889,"the, and, sequence, bat"
51098,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.088888889,"the, sequence, sars-cov-2, coronaviruses"
51099,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.088888889,"in, the, with, at"
51100,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.088888889,"coronavirus, to, can, be"
51101,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.088888889,"one, is, to, in"
51102,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.088888889,"to, in, the, ratg13"
51103,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.088888889,"the, to, a, ratg13"
51104,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.088888889,"the, a, in, for"
51105,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.088888889,"the, with, sars-cov-2, as"
51106,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.088888889,"the, same, with, sars-cov-2"
51107,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.088888889,"pangolin-cov, with, the, as"
51108,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.088888889,"ace2, a, sars-cov-2, and"
51109,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.088888889,"potential, between, sars-cov-2, and"
51110,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.088888889,"the, to, sars-cov-2, a"
51111,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.088888889,"the, spread, and, also"
51112,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.088888889,"and, the, of, also, to, infect, for, is"
51113,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.088888889,"also, for, the, and"
51114,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.088888889,"to, the, from, spillover"
51115,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.088888889,"a, to, the, intermediate"
51116,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.088888889,"of, covid-19, to, the"
51117,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.088888889,"to, and, the, species"
51118,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.088888889,"the, to, and, species"
51119,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.088888889,"in, sars-cov-2, were, to"
51120,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.088888889,"to, with, coronavirus, bat"
51121,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan",0.088888889,"wuhan, in, live, of"
51122,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.088888889,"sars-cov-2, the, that, in"
51123,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.088888889,"virus, is, sars-cov-2, genome"
51124,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.088888889,"to, virus, the, sars-cov-2"
51125,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.088888889,"sars-cov-2, a, to, in"
51126,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.088888889,"in, more, the, reservoirs"
51127,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.088888889,"of, the, are, in"
51128,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.088888889,"of, most, the, and"
51129,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.088888889,"the, of, viral, and"
51130,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Bats are the second  

largest order of mammals, with over 1,230 species.",0.088888889,"the, are, with, of"
51131,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.088888889,"the, bats, likely, sars-cov-2"
51132,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.088888889,"the, are, to, in, southern, most, that, and"
51133,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.088888889,"the, that, in, southeast"
51134,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.088888889,"bat, that, and, sars-cov-2"
51135,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.088888889,"to, the, and, for"
51136,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.088888889,"in, of, and, to"
51137,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.088888889,"the, of, in, region"
51138,"�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.088888889,"bat, and, the, same"
51139,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.088888889,"the, same, in, of"
51140,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.088888889,"a, that, in, bat"
51141,"This suggests that the BANAL series may be able to directly infect  

humans.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.088888889,"that, the, to, infect"
51142,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.088888889,"the, of, to, is, also, for, infect, and"
51143,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.088888889,"the, to, this, that, in, contact, with, of"
51144,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.088888889,"to, this, that, the, virus, bats, of, recombination"
51145,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.088888889,"sars-cov-2, to, a, which"
51146,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.088888889,"of, sars-cov-2, from, to"
51147,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.088888889,"which, to, of, from"
51148,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.088888889,"to, sars-cov-2, a, from"
51149,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.088888889,"known, of, a, to"
51150,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.088888889,"he, at, the, by"
51151,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.088888889,"the, genome, bat, coronavirus"
51152,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.088888889,"it, sars-cov-2, a, related"
51153,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.088888889,"the, of, like, and"
51154,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.088888889,"is, the, that, are"
51155,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",all three BANAL series viruses also use ACE2 as an entry receptor.,0.088888889,"also, use, as, an"
51156,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.088888889,"that, the, ace2, to"
51157,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.088888889,"to, the, that, human"
51158,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.088888889,"the, that, binds, ace2"
51159,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.088888889,"of, have, to, sars-cov-2."
51160,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","This suggests that the BANAL series may be able to directly infect  

humans.",0.088888889,"that, the, infect, to"
51161,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.088888889,"of, the, from, in"
51162,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.088888889,"the, in, of, is"
51163,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.088888889,"have, the, at, a"
51164,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.088888889,"of, viruses, a, the"
51165,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.088888889,"a, furin, cleavage, site"
51166,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.088888889,"the, a, at, of"
51167,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.088888889,"a, to, the, and"
51168,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.088888889,"a, the, and, two"
51169,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.088888889,"to, the, viruses, and"
51170,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.088888889,"have, the, a, and"
51171,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.088888889,"the, sars-cov-2, and, for"
51172,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.088888889,"to, the, of, as"
51173,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.088888889,"after, of, to, the"
51174,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.088888889,"as, first, and, in"
51175,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.088888889,"sars-cov-2, the, virus, in"
51176,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.088888889,"in, sars-cov-2, to, be"
51177,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.088888889,"there, sars-cov-2, a, in"
51178,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.088888889,"the, may, a, these"
51179,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.088888889,"rmyn02,, in, the, bat"
51180,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.088888889,"coronaviruses, are, a, common"
51181,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.088888889,"the, that, sars-cov-2, humans"
51182,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.088888889,"that, is, covid-19, in"
51183,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.088888889,"and, infected, the, is"
51184,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.088888889,"sars-cov-2, the, in, and"
51185,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.088888889,"the, with, early, that"
51186,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.088888889,"or, bats, the, by, species, of, to, as, civets, and, in, also"
51187,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.088888889,"the, first, was, in, that, bat, as, for"
51188,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.088888889,"introductions, were, in, to, sampled, the, animal, other"
51189,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.088888889,"all, a, zoonotic, species, of, animals,, to, and"
51190,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.088888889,"and, the, virus, from, to, a, in, china"
51191,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.088888889,"the, virus, animal, in, market, infected, to, and"
51192,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.088888889,"the, to, that, are, most, in, southern, and"
51193,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.088888889,"the, to, for, a, animals, is, most, likely"
51194,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.088888889,"the, for, a, of, to, with, from, and"
51195,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.088888889,"in, but, to, is, of, the, covid-19, and"
51196,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.088888889,"this, that, the, more, likely, of, sars-cov-2, than"
51197,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.088888889,"known, to, of, a"
51198,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.088888889,"the, of, to, suggesting"
51199,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.088888889,"is, with, a, the"
51200,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.088888889,"sars-cov-2, to, the, its"
51201,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","Those who eagerly peddle suggestions of 

laboratory involvement have consistently failed to present 

credible arguments to support their positions.",0.088888889,"laboratory, to, those, of"
51202,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","expended to make the simple point 

that COVID-19 had a natural origin.",0.088888889,"the, that, a, to"
51203,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.088888889,"to, sars-cov-2, from, bats"
51204,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.088888889,"were, to, and, that"
51205,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.088888889,"in, bats, rhinolophus, china"
51206,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.088888889,"that, pangolins, sars-cov-2, in"
51207,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.088888889,"in, and, that, sars-cov-2"
51208,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.088888889,"in, that, bats, sars-cov-2"
51209,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.088888889,"also, unlikely, from, the"
51210,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.088888889,"sars-cov-2, in, origin, and"
51211,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.088888889,"the, virus, genome,, that"
51212,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.088888889,"the, that, virus, a"
51213,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.088888889,"that, is, a, or"
51214,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.088888889,"it, that, a, of"
51215,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.088888889,"it, a, related, sars-cov-2"
51216,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.088888889,"a, of, sars-cov-2, is"
51217,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.088888889,"from, that, virus, the"
51218,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.088888889,"is, the, that, from"
51219,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.088888889,"that, from, the, is"
51220,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.088888889,"a, it, the, in"
51221,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.088888889,"an, was, in, the"
51222,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.088888889,"and, sars-cov-2, of, more"
51223,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.088888889,"coronaviruses, the, of, and"
51224,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.088888889,"the, of, and, like"
51225,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.088888889,"finding, and, the, of"
51226,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.088888889,"in, through, from, animals"
51227,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.088888889,"the, that, not, a"
51228,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.088888889,"the, of, that, covid-19"
51229,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.088888889,"bat, coronavirus, the, genome"
51230,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.088888889,"of, a, genome, bat"
51231,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.088888889,"the, coronavirus, in, pangolins,"
51232,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.088888889,"that, the, binds, ace2"
51233,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.088888889,"that, the, based, on"
51234,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.088888889,"genetic, the, in, to"
51235,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.088888889,"to, bats, and, the"
51236,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.088888889,"sequence, identity, cov, and"
51237,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.088888889,"to, in, the, cov"
51238,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.088888889,"the, to, from, evidence"
51239,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.088888889,"a, of, animal, species"
51240,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.088888889,"evidence, that, hosts, for"
51241,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.088888889,"viruses, of, have, is"
51242,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.088888889,"and, that, bats, of"
51243,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.088888889,"that, suggests, hosts, in"
51244,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.088888889,"a, large, of, group"
51245,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.088888889,"are, a, coronaviruses, common"
51246,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.088888889,"to, in, the, is"
51247,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.088888889,"the, have, of, most"
51248,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.088888889,"that, of, in, which"
51249,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.088888889,"have, that, the, in"
51250,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.088888889,"of, by, in, the"
51251,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.088888889,"the, by, was, of"
51252,"identified numerous human–animal interactions that con- 

stitute emergence risk factors, for example bat tourism, wet 

markets, wildlife supply chains for human consumption,15 land 

management practices, and environmental perturbations.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.088888889,"that, for, bat, and"
51253,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.088888889,"the, most, of, and"
51254,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.088888889,"of, to, was, bat"
51255,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.088888889,"that, the, to, suggesting, these, in, of, and"
51256,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.088888889,"the, that, in, virus"
51257,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.088888889,"the, virus, that, with"
51258,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.088888889,"the, that, with, virus"
51259,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.088888889,"two, of, the, in"
51260,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.088888889,"the, not, in, reported"
51261,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.088888889,"the, of, to, with, that, contact, this, in"
51262,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.088888889,"it, that, the, to"
51263,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.088888889,"studies, the, a, in"
51264,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.088888889,"in, rhinolophus, bats, china"
51265,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.088888889,"the, of, that, no"
51266,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.088888889,"the, may, host, of"
51267,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.088888889,"in, of, with, bats"
51268,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.088888889,"the, to, would, from"
51269,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.088888889,"the, bats, intermediate, humans"
51270,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.088888889,"and, closely, related, bats"
51271,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.088888889,"and, caused, by, bats"
51272,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.088888889,"the, in, an, was"
51273,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.088888889,"to, virus, bats, be"
51274,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.088888889,"the, of, et, al., which, may, as, to"
51275,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.088888889,"by, the, of, in, species, to, bats, civets, as, and, or, also"
51276,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.088888889,"sars-cov-2, origin, and, in"
51277,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.088888889,"viruses, have, is, of"
51278,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.088888889,"the, two, of, in"
51279,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.088888889,"of, sars-cov-2, been, the"
51280,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.088888889,"sars-cov-2, the, with, guangdong"
51281,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.088888889,"bats, or, pangolins, the"
51282,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.088888889,"is, and, that, of"
51283,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.088888889,"and, of, is, that"
51284,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.088888889,"related, to, a, which"
51285,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.088888889,"the, animals, to, a, for, is, most, likely"
51286,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.088888889,"to, the, most, is"
51287,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.088888889,"the, likely, to, a"
51288,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.088888889,"the, is, a, for"
51289,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.088888889,"that, has, a, human"
51290,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.088888889,"cov, that, human, and"
51291,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.088888889,"been, and, genome, sars-cov-2"
51292,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.088888889,"that, sars-cov-2, bat, and"
51293,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.088888889,"sequence, identity, and, cov"
51294,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.088888889,"identity, suggesting, that, sars-cov-2"
51295,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.088888889,"species,, such, as, humans"
51296,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.088888889,"of, for, to, zoonotic"
51297,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.088888889,"was, a, of, on"
51298,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.088888889,"the, coronavirus, with, not"
51299,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.088888889,"not, the, in, by"
51300,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.088888889,"sars-cov-2, from, in, to"
51301,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.088888889,"an, to, that, from"
51302,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.088888889,"sars-cov-2, to, a, in"
51303,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.088888889,"it, not, an, to"
51304,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.088888889,"a, that, sars-cov-2, or"
51305,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.088888889,"to, sars-cov-2, as, humans"
51306,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.088888889,"in, to, sars-cov-2, humans"
51307,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.088888889,"that, to, in, sars-cov-2"
51308,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.088888889,"that, sars-cov-2, they, in"
51309,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.088888889,"for, sars-cov, and, the"
51310,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.088888889,"have, been, and, the"
51311,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.088888889,"that, human, the, a, of, genetic, is, natural"
51312,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",Genetic evidence suggesting otherwise is yet to be presented.,0.088888889,"to, be, genetic, is"
51313,"bats are also important reservoir species for a great 

range of coronaviruses","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.088888889,"are, also, for, of"
51314,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.088888889,"the, viral, of, and"
51315,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.088888889,"by, in, the, not"
51316,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.088888889,"that, are, more, sars-cov-2, to, in, of, and"
51317,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.088888889,"genome, of, than, bat"
51318,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.088888889,"be, the, viruses, that"
51319,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.088888889,"the, that, as, evidence"
51320,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.088888889,"the, has, been, to"
51321,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.088888889,"the, hypothesis, that, is"
51322,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.088888889,"the, and, has, been"
51323,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.088888889,"to, of, the, other"
51324,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.088888889,"the, to, of, with"
51325,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.088888889,"sars-cov-2, from, and, of"
51326,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.088888889,"the, was, to, in, its, of, bats,, sars-cov-2"
51327,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.088888889,"sars-cov-2, its, to, the"
51328,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.088888889,"in, the, of, these"
51329,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.088888889,"a, that, is, in"
51330,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.088888889,"to, the, in, of, and, suggesting, that, these"
51331,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.088888889,"in, are, more, to, that, of, sars-cov-2, and"
51332,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.088888889,"the, to, is, most"
51333,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.088888889,"bats, that, hosts, for"
51334,"Based on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.088888889,"based, on, the, that"
51335,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.088888889,"bats, pangolins, the, or"
51336,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.088888889,"that, a, sars-cov-2, coronavirus"
51337,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.088888889,"a, bat, from, sars-cov-2"
51338,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.088888889,"and, that, bats, for"
51339,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.088888889,"virus, that, the, for"
51340,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.088888889,"the, level,, that, virus"
51341,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.088888889,"the, that, sars-cov-2, as"
51342,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.088888889,"that, sars-cov-2, the, for"
51343,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.088888889,"the, to, it, that"
51344,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.088888889,"that, the, to, as"
51345,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.088888889,"of, in, the, by"
51346,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.088888889,"the, in, of, sars-cov-2"
51347,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.088888889,"of, a, the, bat"
51348,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.088888889,"using, the, in, sars-cov-2"
51349,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.088888889,"to, genome, bat, coronavirus,"
51350,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.088888889,"of, genome, a, bat"
51351,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.088888889,"of, to, bat, was"
51352,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.088888889,"is, sars-cov-2, of, a"
51353,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.088888889,"of, genomic, similar, to"
51354,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.088888889,"et, and, to, of"
51355,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.088888889,"have, of, to, sars-cov-2."
51356,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.088888889,"in, similar, to, of"
51357,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.088888889,"that, sars-cov-2, in, pangolins"
51358,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.088888889,"suggests, that, in, hosts"
51359,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.088888889,"the, a, intermediate, to"
51360,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.088888889,"as, the, to, sars-cov-2"
51361,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.088888889,"the, to, sars-cov-2, been"
51362,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.088888889,"that, bat, with, sars-cov-2"
51363,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.088888889,"the, are, is, that"
51364,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.088888889,"this, that, the, for"
51365,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same",0.088888889,"and, bat, the, same"
51366,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.088888889,"the, with, bat, to"
51367,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.088888889,"cov, have, in, which"
51368,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.088888889,"the, to, cov, in"
51369,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.088888889,"of, the, by, that, sars-cov-2, and, are, in"
51370,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.088888889,"that, the, in, further"
51371,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.088888889,"sars-cov-2, using, the, in"
51372,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.088888889,"the, pangolin, and, that"
51373,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.088888889,"guangdong, with, sars-cov-2, the"
51374,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.088888889,"the, of, that, this, sars-cov-2, more, likely, than"
51375,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.088888889,"of, that, the, origin"
51376,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.088888889,"and, of, this, the"
51377,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.088888889,"the, bat, and, sars-cov-2"
51378,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.088888889,"the, of, from, origin"
51379,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.088888889,"of, the, genome, and"
51380,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.088888889,"studies, the, of, and"
51381,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.088888889,"to, genome, the, sars-cov-2"
51382,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.088888889,"to, a, ratg13, the"
51383,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.088888889,"the, to, a, likely"
51384,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.088888889,"to, sars-cov, and, the"
51385,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.088888889,"and, the, sars-cov-2, with"
51386,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.088888889,"of, sars-cov-2, to, with"
51387,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.088888889,"of, the, with, but"
51388,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.088888889,"that, for, and, the"
51389,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.088888889,"of, and, for, in"
51390,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.088888889,"the, that, between, and"
51391,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.088888889,"and, in, the, from"
51392,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.088888889,"the, in, a, and"
51393,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.088888889,"from, in, the, and"
51394,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.088888889,"and, have, a, the"
51395,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.088888889,"a, that, the, for"
51396,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.088888889,"all, sars-cov-2, isolated, from"
51397,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.088888889,"sars-cov-2, and, with, the"
51398,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.088888889,"sars-cov-2, the, and, is"
51399,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.088888889,"the, are, and, in"
51400,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.088888889,"the, finding, of, and"
51401,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.088888889,"this, the, that, for"
51402,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.088888889,"in, the, that, for"
51403,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.088888889,"that, the, of, pangolin"
51404,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.088888889,"the, that, to, from"
51405,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.088888889,"the, of, suggesting, to"
51406,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.088888889,"the, not, to, of"
51407,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.088888889,"sars-cov-2, is, virus, that"
51408,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.088888889,"the, of, which, is"
51409,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.088888889,"the, of, to, bats, that, this, recombination, virus"
51410,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.088888889,"revealed, between, and, at"
51411,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.088888889,"of, to, the, transmission"
51412,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.088888889,"from, of, to, the"
51413,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.088888889,"of, the, a, with"
51414,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.088888889,"the, to, rbd, of"
51415,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.088888889,"the, that, as, was"
51416,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.088888889,"the, was, for, first, that, bat, as, in"
51417,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.088888889,"is, to, that, sars-cov-2"
51418,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.088888889,"of, and, bat, the"
51419,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.088888889,"the, at, for, that"
51420,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.088888889,"virus, been, the, sars-cov-2"
51421,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.088888889,"the, for, a, is"
51422,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.088888889,"that, a, sars-cov-2, or"
51423,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.088888889,"the, an, to, and"
51424,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.088888889,"not, to, it, an"
51425,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.088888889,"the, of, to, not"
51426,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.088888889,"from, sars-cov-2, a, bat"
51427,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.088888889,"the, also, for, and"
51428,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.088888889,"that, sars-cov-2, in, of"
51429,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.088888889,"infected, in, may, common"
51430,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.088888889,"of, a, zoonotic, in"
51431,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.088888889,"to, sars-cov-2, were, in"
51432,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.088888889,"to, sars-cov-2, be, in"
51433,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.088888889,"for, to, zoonotic, of"
51434,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.088888889,"the, has, in, found"
51435,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.088888889,"to, in, the, that"
51436,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.088888889,"in, of, similar, to"
51437,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.088888889,"that, animal, to, a"
51438,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.088888889,"is, to, of, and"
51439,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.088888889,"of, ratg13, to, in"
51440,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.088888889,"sars-cov-2, as, of, from"
51441,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.088888889,"that, found, of, with"
51442,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.088888889,"of, the, that, pangolin-cov"
51443,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.088888889,"the, pangolin-cov, as, with"
51444,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.088888889,"the, also, to, of"
51445,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.088888889,"that, the, as, to"
51446,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.088888889,"ratg13,, the, to, of"
51447,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.088709677,"in, the, a, year, to, with, novel, coronaviruses, and, that, from"
51448,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.088709677,"the, of, a, study, on, bat, as, with, and, it, reservoir"
51449,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.088709677,"the, for, of, a, to, that, in, is, sars, likely, by"
51450,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.088709677,"the, for, to, a, virus, that, with, by, sars, in, of"
51451,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.088709677,"and, at, the, that, was, for, of, in, from, a, by"
51452,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.088709677,"a, positive, samples, collected, and, were, to, of, located, in, the"
51453,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.088709677,"a, of, in, that, for, sars, with, by, the, to, virus"
51454,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.088709677,"in, the, year, a, novel, that, coronaviruses, from, to, and, with"
51455,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.088709677,"a, study, the, on, as, reservoir, of, bat, and, it, with"
51456,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.088709677,"the, of, is, by, for, likely, in, a, to, sars, that"
51457,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.088709677,"a, of, the, and, were, in, to, samples, positive, collected, located"
51458,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.088709677,"in, the, of, from, that, for, at, was, by, a, and"
51459,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.088607595,"a, of, the, sars-cov-2, that, and, novel"
51460,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.088607595,"the, of, known, to, and, in, sars-cov"
51461,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.088607595,"the, as, a, of, that, to, and"
51462,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.088607595,"in, with, the, and, to, that, are"
51463,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.088607595,"with, and, to, that, sars-cov-2, sars-, cov-2"
51464,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.088607595,"that, the, of, and, are, origin, sars-cov-2"
51465,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.088607595,"for, from, at, the, huanan, market, of"
51466,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.088607595,"the, be, of, are, known, to, and"
51467,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.088607595,"into, and, the, of, that, sars-cov-2, in"
51468,"expended to make the simple point 

that COVID-19 had a natural origin.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.088607595,"to, the, that, had, a, natural, origin."
51469,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.088607595,"in, and, to, that, sars-cov-2, is, are"
51470,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.088607595,"the, of, to, be, for, and, some"
51471,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.088607595,"to, the, virus, be, of, sars-cov-2,, we"
51472,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.088607595,"would, be, in, the, research, laboratory, for"
51473,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.088607595,"that, have, of, to, and, a, all"
51474,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.088607595,"in, the, and, to, of, as, they"
51475,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.088607595,"the, of, for, a, virus, to, that"
51476,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.088607595,"and, the, that, for, of, from, a"
51477,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.088607595,"the, of, is, in, virus, to, genetic"
51478,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.088607595,"the, that, in, were, to, and, who"
51479,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.088607595,"with, the, and, is, of, bat, as"
51480,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.088607595,"and, sars-cov-2, with, bat, cov, that, the"
51481,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.088607595,"a, of, the, from, that, in, were"
51482,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.088607595,"sars-cov-2, of, a, novel, that, and, the"
51483,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.088607595,"the, of, sars-cov-2,, in, and, that, a"
51484,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.088607595,"at, seafood, in, hubei, the, of, found"
51485,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.088607595,"or, of, such, as, in, been, other"
51486,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.088607595,"the, of, have, a, which, to, and"
51487,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.088607595,"and, the, of, bat, populations, a, in"
51488,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.088607595,"sars-cov-2, of, for, to, in, and, the"
51489,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.088607595,"the, is, that, of, by, a, not"
51490,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.088607595,"on, in, the, and, that, to, between"
51491,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.088607595,"the, of, and, to, for, be, some"
51492,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.088607595,"the, of, a, and, in, bat, populations"
51493,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.088607595,"the, virus, for, a, of, to, that"
51494,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.088607595,"in, to, is, of, the, virus, genetic"
51495,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.088607595,"the, to, closely, related, in, virus, is"
51496,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.088607595,"to, humans, or, with, of, and, in"
51497,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.088607595,"the, for, of, from, at, huanan, market"
51498,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.088607595,"all, have, a, that, of, to, and"
51499,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.088607595,"who, the, were, to, that, in, and"
51500,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.088607595,"the, that, of, not, is, by, a"
51501,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.088607595,"to, the, in, of, and, a, covid-19"
51502,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.088607595,"the, for, a, of, that, from, and"
51503,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.088607595,"of, that, the, a, from, or, for"
51504,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.088607595,"that, and, to, on, the, between, in"
51505,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","expended to make the simple point 

that COVID-19 had a natural origin.",0.088607595,"that, to, the, had, a, natural, origin."
51506,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.088607595,"more, the, sars-cov-2, these, with, of, and"
51507,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.088607595,"the, that, or, for, of, from, a"
51508,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.088607595,"of, covid-19, a, to, and, the, in"
51509,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.088607595,"of, and, in, or, humans, with, to"
51510,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.088607595,"the, known, sars-cov, and, to, in, of"
51511,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.088607595,"been, in, other, of, such, as, or"
51512,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.088607595,"of, also, to, which, the, in, these"
51513,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.088607595,"have, the, of, to, a, and, which"
51514,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.088607595,"a, as, the, of, and, that, to"
51515,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.088607595,"the, of, and, that, sars-cov-2, into, in"
51516,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.088607595,"that, the, of, is, are, natural, sars-cov-2"
51517,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.088607595,"sars-cov-2, of, based, on, and, to, in"
51518,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.088607595,"which, the, these, of, to, in, also"
51519,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.088607595,"the, of, with, and, more, sars-cov-2, these"
51520,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.088607595,"that, with, the, of, suggesting, may, to"
51521,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.088607595,"in, the, hubei, of, found, at, seafood"
51522,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.088607595,"the, by, of, in, (2020), that, a"
51523,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.088607595,"a, by, (2020), in, that, the, of"
51524,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.088607595,"cov, with, bat, that, the, sars-cov-2, and"
51525,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.088607595,"in, the, that, are, to, and, with"
51526,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.088607595,"that, sars-cov-2, with, sars-, cov-2, and, to"
51527,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.088607595,"are, that, sars-cov-2, to, and, is, in"
51528,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.088607595,"as, the, of, and, in, they, to"
51529,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.088607595,"the, as, of, bat, is, and, with"
51530,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.088607595,"origin, of, the, that, sars-cov-2, and, are"
51531,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.088607595,"and, the, of, that, in, for, recombination"
51532,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.088607595,"of, for, a, have, that, and, the"
51533,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.088607595,"the, of, we, to, be, sars-cov-2,, virus"
51534,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.088607595,"in, the, research, for, would, be, laboratory"
51535,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.088607595,"in, the, of, a, at, that, to"
51536,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.088607595,"the, that, are, of, natural, sars-cov-2, is"
51537,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.088607595,"that, the, to, suggesting, may, with, of"
51538,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.088607595,"in, to, of, sars-cov-2, based, on, and"
51539,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.088495575,"as, a, result, of, the, public, to, evidence, that, from"
51540,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.088495575,"the, live, were, in, with, of, a, as, that, infected"
51541,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.088495575,"sars-cov-2, and, of, the, with, sars-cov, 50%, that, bat, covs"
51542,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.088495575,"with, bat, covs, that, the, of, sars-cov-2, and, 50%, sars-cov"
51543,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.088495575,"the, as, for, and, a, in, of, species, that, or"
51544,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.088495575,"the, of, to, bat, as, and, likely, reservoir, species, horseshoe"
51545,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.088495575,"a, the, by, collected, earliest, identified, were, suggesting, of, and"
51546,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.088495575,"evidence, to, the, public, that, as, a, result, of, from"
51547,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.088495575,"in, a, of, species, and, that, the, as, or, for"
51548,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.088495575,"the, horseshoe, species, likely, to, as, reservoir, of, bat, and"
51549,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.088495575,"collected, by, a, of, the, were, identified, and, suggesting, earliest"
51550,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.088495575,"that, the, infected, with, in, live, were, as, a, of"
51551,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.088235294,"bats, reservoir, a"
51552,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.088235294,"of, natural, the, and, viruses, virus"
51553,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.088235294,"are, a, in"
51554,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.088235294,"animal, of, a"
51555,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","An enormous reservoir of coronaviruses infects hundreds of bat 

species distributed globally",0.088235294,"reservoir, an, of"
51556,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.088235294,"and, coronavirus, bats, of, with, or"
51557,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.088235294,"have, to, bat"
51558,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.088235294,"bat, in, coronaviruses"
51559,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.088235294,"sars-cov-2, in, of"
51560,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.088235294,"of, and, in"
51561,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.088235294,"more, in, of"
51562,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.088235294,"of, which, to, in, and, sars-cov"
51563,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.088235294,"sars-cov, and, many"
51564,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.088235294,"of, bats, and"
51565,"insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.088235294,"from, of, and"
51566,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.088235294,"from, bats, and"
51567,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.088235294,"identified, the, to"
51568,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.088235294,"sars-cov-2, such, genome"
51569,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.088235294,"virus, in, to"
51570,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.088235294,"to, is, its"
51571,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.088235294,"sars-cov-2, virus, to"
51572,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.088235294,"and, for, a"
51573,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.088235294,"also, the, same"
51574,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.088235294,"the, virus, into, human, with, of, occurred, have, to"
51575,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.088235294,"as, the, was, to, with, of"
51576,hese close genetic relations suggest that they all have their ecological origin in bat populations,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.088235294,"that, have, origin"
51577,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.088235294,"be, that, of, sars-cov-2, a, by"
51578,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.088235294,"the, of, to, it, that, sars-cov-2"
51579,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.088235294,"to, the, have, been, of, that"
51580,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.088235294,"coronaviruses, to, that, of, sars-cov-2, sequences"
51581,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.088235294,"have, which, from"
51582,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.088235294,"which, have, from"
51583,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.088235294,"which, from, is"
51584,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.088235294,"to, other, be, of, and, in"
51585,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.088235294,"and, a, that"
51586,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.088235294,"shares, with, that"
51587,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.088235294,"virus, and, other"
51588,Many of these CoVs can infect several animal species as well,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.088235294,"many, of, these"
51589,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.088235294,"the, and, that, of, to, all"
51590,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.088235294,"bat, have, to"
51591,hese close genetic relations suggest that they all have their ecological origin in bat populations,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.088235294,"that, have, bat"
51592,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.088235294,"the, host, that, with, as, to"
51593,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.088235294,"as, to, the, that, sars-cov-2, have"
51594,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.088235294,"virus, as, of"
51595,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.088235294,"virus, of, and"
51596,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.088235294,"genome, of, virus"
51597,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.088235294,"of, bat, genome"
51598,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.088235294,"has, origin, bat"
51599,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.088235294,"a, the, are"
51600,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.088235294,"of, between, and"
51601,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.088235294,"sequence, with, of"
51602,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.088235294,"most, are, of"
51603,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.088235294,"to, similar, sars-cov-2"
51604,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.088235294,"in, is, that, the, be, and"
51605,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.088235294,"as, a, of, the, and, in, an, to, with, for, that, host"
51606,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.088235294,"in, of, as"
51607,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.088235294,"in, the, malayan"
51608,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.088235294,"of, the, that, covid-19, were, wuhan"
51609,"unnatural origin of SARS-CoV-2, but these people are 

simply wrong","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.088235294,"origin, of, people"
51610,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.088235294,"in, this, that, the, origin, is"
51611,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.088235294,"most, has, bats"
51612,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.088235294,"and, the, to, from, species, animals"
51613,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.088235294,"sars-cov-2, at, the"
51614,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.088235294,"the, sars-cov-2, covid-19"
51615,"t some virus detected in pangolins 

were capable of infecting humans.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.088235294,"t, detected, in"
51616,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.088235294,"the, coronavirus, zoonotic"
51617,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.088235294,"zoonotic, from, the"
51618,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.088235294,"to, severe, and"
51619,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.088235294,"through, the, animals"
51620,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.088235294,"from, the, in"
51621,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.088235294,"in, the, from"
51622,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.088235294,"the, natural, that"
51623,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.088235294,"in, the, from, and, a, animals"
51624,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.088235294,"coronaviruses, to, in, the, that, for"
51625,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.088235294,"to, that, the, and, for, are"
51626,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.088235294,"the, are, to"
51627,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","with the first case being linked to  

a seafood market",0.088235294,"with, to, the, seafood, market, a"
51628,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","with the first case being linked to  

a seafood market",0.088235294,"the, market, to, case, with, a"
51629,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.088235294,"a, that, zoonotic"
51630,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.088235294,"which, the, in"
51631,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.088235294,"a, scientists, the, virus, that, was"
51632,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.088235294,"a, the, it, virus, that, not"
51633,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.088235294,"the, that, not"
51634,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.088235294,"the, it, that, was, a, by"
51635,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.088235294,"that, not, a"
51636,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.088235294,"to, that, sars-, cov-2, and, sars-cov-2"
51637,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.088235294,"a, likely, sars-cov-2, and, to, an"
51638,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.088235294,"are, to, in, a, as, reservoir, likely, animal, and"
51639,"insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.088235294,"from, of, as"
51640,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.088235294,"such, sars-cov-2, genome"
51641,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.088235294,"the, natural, has"
51642,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.088235294,"that, sars-cov-2, through"
51643,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.088235294,"have, sars-cov-2, the"
51644,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.088235294,"other, sars-cov-2, from"
51645,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.088235294,"from, zoonotic, with"
51646,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.088235294,"sars-cov-2, from, and"
51647,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.088235294,"that, were, sars-cov-2, in, and, from"
51648,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.088235294,"that, sars-cov-2, the, at, of, and"
51649,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.088235294,"the, of, from, zoonotic, by, a"
51650,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.088235294,"into, the, sars-cov-2"
51651,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.088235294,"most, humans, intermediate"
51652,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.088235294,"probable, for, sars-cov-2"
51653,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.088235294,"the, through, animals"
51654,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.088235294,"of, market, that, the, transmission, to"
51655,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.088235294,"the, of, that, jumped, humans, and"
51656,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.088235294,"are, the, a"
51657,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.088235294,"closely, related, in"
51658,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.088235294,"2019, with, of"
51659,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.088235294,"a, of, market, in, with, the"
51660,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.088235294,"the, in, origin"
51661,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.088235294,"the, of, virus, from, a, taken"
51662,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.088235294,"from, was, by, the, of, a"
51663,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.088235294,"the, more, than"
51664,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.088235294,"in, the, likely, that, was, market"
51665,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.088235294,"and, an, in"
51666,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.088235294,"an, animal, likely"
51667,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.088235294,"the, of, in, a, and, to"
51668,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.088235294,"a, of, zoonotic, and, the, to"
51669,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.088235294,"that, sars-cov-2, with"
51670,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.088235294,"the, three, of"
51671,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.088235294,"of, yet, the"
51672,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.088235294,"in, the, a, from, animals, and"
51673,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.088235294,"also, the, of, cases, in, to"
51674,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.088235294,"to, sars-cov-2, in, the, that, of"
51675,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.088235294,"a, of, the, at, has, been, by, that, to"
51676,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.088235294,"we, for, and, in, the, of"
51677,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.088235294,"the, of, sars-cov-2, to, is, most, or, that, not"
51678,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.088235294,"that, have, by, of, to, and, are, the, sars-cov-2"
51679,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.088235294,"cases, with, the, were, market., earliest"
51680,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.088235294,"to, the, as, a, in, from, that, genome, humans"
51681,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.088235294,"a, that, the, virus, was, scientists"
51682,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.088235294,"the, market, was, likely, that, in"
51683,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.088235294,"the, of, covid-19, to, that, scientists"
51684,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.088235294,"analysis, that, the, of, a, covid-19"
51685,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.088235294,"not, a, that, the, virus, it"
51686,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.088235294,"there, is, that"
51687,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.088235294,"evidence, that, from"
51688,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.088235294,"sars-cov-2, an, to, a, likely, and"
51689,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.088235294,"the, is, that, of, and, but"
51690,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.088235294,"of, the, a, to, that, naturally"
51691,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.088235294,"the, of, for, to, see, that"
51692,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.088235294,"as, of, from"
51693,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.088235294,"of, such, as"
51694,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.088235294,"of, and, from"
51695,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.088235294,"from, bats,, and"
51696,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.088235294,"the, on, and, with, a, as, to, that, virus"
51697,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.088235294,"a, zoonotic, to"
51698,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.088235294,"of, and, species, that, a, to"
51699,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.088235294,"from, which, have"
51700,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.088235294,"horseshoe, in, of"
51701,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.088235294,"and, is, to"
51702,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.088235294,"and, to, is"
51703,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.088235294,"is, to, through"
51704,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.088235294,"is, very, to"
51705,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.088235294,"was, animal, host"
51706,"All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.088235294,"the, in, a"
51707,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.088235294,"of, the, possible"
51708,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.088235294,"in, the, of, that, market, to, were, a, and"
51709,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.088235294,"the, of, virus, in, that, to"
51710,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.088235294,"cases, in, also, the, of, to"
51711,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.088235294,"the, authors, also, of, they, as"
51712,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.088235294,"to, the, and, of, from, horseshoe, that, an, identical"
51713,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.088235294,"the, and, that, of, to, from"
51714,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.088235294,"to, the, bats, as, be, and, a, from, that"
51715,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.088235294,"the, identified, to"
51716,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.088235294,"with, a, the"
51717,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.088235294,"from, a, to"
51718,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.088235294,"have, the, a"
51719,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.088235294,"he, and, to"
51720,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.088235294,"with, the, and, to, sars-cov-2, of"
51721,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.088235294,"and, from, to, the, of, sars-cov-2"
51722,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.088235294,"from, sars-cov-2, the"
51723,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.088235294,"sars-cov-2, although, with"
51724,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.088235294,"human, to, the"
51725,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.088235294,"of, to, and"
51726,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.088235294,"in, transmitted, to"
51727,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.088235294,"bats, and, a, to, that, in"
51728,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.088235294,"of, scientists, to, the, that, covid-19"
51729,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.088235294,"most, to, through"
51730,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.088235294,"is, at, the"
51731,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.088235294,"the, is, all"
51732,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.088235294,"as, was, the"
51733,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.088235294,"that, the, its"
51734,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.088235294,"and, the, bat"
51735,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.088235294,"with, the, bat"
51736,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.088235294,"to, bats, the"
51737,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.088235294,"the, and, sequence"
51738,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.088235294,"the, of, identity"
51739,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.088235294,"and, the, to, be, is, natural"
51740,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.088235294,"on, sequence, the, of, a, for"
51741,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.088235294,"could, be, the"
51742,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.088235294,"could, be, they"
51743,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.088235294,"market, in, the"
51744,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.088235294,"been, the, origin."
51745,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.088235294,"the, and, not"
51746,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.088235294,"the, to, that, sars-cov-2, is, bat"
51747,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.088235294,"the, outbreak, in"
51748,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.088235294,"a, bat, be, that, coronavirus, bats"
51749,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.088235294,"the, by, receptor, and, that, a"
51750,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.088235294,"as, of, the, was, to, with"
51751,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.088235294,"the, of, for, to, with, and"
51752,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.088235294,"or, of, and, the, bats, transmission"
51753,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.088235294,"and, of, which, the, for, to"
51754,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.088235294,"bat, to, is"
51755,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.088235294,"and, in, humans"
51756,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.088235294,"the, of, that, sars-cov-2, with, and"
51757,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.088235294,"and, similarity, of, sars-cov-2, the, viral"
51758,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.088235294,"the, bat, that"
51759,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.088235294,"been, of, coronaviruses"
51760,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.088235294,"have, to, may"
51761,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.088235294,"to, have, sars-cov-2"
51762,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.088235294,"the, of, from, a, in, as"
51763,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.088235294,"from, as, the, of, in, a"
51764,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.088235294,"is, most, likely"
51765,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.088235294,"covid-19, in, the"
51766,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.088235294,"in, bats, the"
51767,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.088235294,"has, the, which"
51768,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.088235294,"the, virus, most"
51769,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.088235294,"the, virus, which"
51770,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.088235294,"the, its, in"
51771,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",Many of these CoVs can infect several animal species as well,0.088235294,"of, many, these"
51772,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.088235294,"an, from, to"
51773,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.088235294,"the, to, when"
51774,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.088235294,"is, a, to"
51775,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.088235294,"the, virus, for"
51776,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.088235294,"a, for, the"
51777,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.088235294,"the, bats, to"
51778,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.088235294,"in, the, outbreak"
51779,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.088235294,"bats, in, to"
51780,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.088235294,"that, origin, have"
51781,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.088235294,"have, that, bat"
51782,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.088235294,"their, that, bat"
51783,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.088235294,"bat, in, close"
51784,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.088235294,"are, the, found"
51785,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.088235294,"have, may, to"
51786,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.088235294,"the, animal, to, have, population, and"
51787,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.088235294,"been, in, animal"
51788,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.088235294,"has, bats, most"
51789,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.088235294,"virus, in, probably"
51790,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.088235294,"most, sars-, cov-2"
51791,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.088235294,"that, and, the"
51792,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.088235294,"and, contact, species, to, be, by"
51793,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.088235294,"had, of, the"
51794,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.088235294,"genome, from, in, the, virus, of"
51795,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.088235294,"virus, genome, of"
51796,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.088235294,"of, the, available"
51797,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.088235294,"the, coronaviruses, to"
51798,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.088235294,"and, in, coronaviruses, are, of, common"
51799,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.088235294,"of, and, bats, with, or, coronavirus"
51800,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.088235294,"of, the, a, as, intermediate, or"
51801,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.088235294,"of, analysis, genomic"
51802,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.088235294,"the, with, coronavirus"
51803,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.088235294,"of, bat, with"
51804,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.088235294,"of, the, bat, and, mers, sars"
51805,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","no modifications were  

recorded for nonstructural proteins NSP7, NSP13  

and the structured and accessory proteins p6 and 8b.",0.088235294,"the, were, and"
51806,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.088235294,"amino, acid, in"
51807,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.088235294,"of, identity, in"
51808,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.088235294,"shows, with, of"
51809,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.088235294,"and, from, that, the, natural, sars-cov-2"
51810,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.088235294,"in, animal, to"
51811,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.088235294,"receptor-binding, domain, receptor"
51812,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.088235294,"and, from, in, to, that, the"
51813,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","the close relation  

between SARS coronavirus and 2019-nCoV",0.088235294,"the, and, between"
51814,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.088235294,"was, that, and"
51815,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.088235294,"a, virus, from, bat, of, and"
51816,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.088235294,"that, in, a"
51817,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.088235294,"in, from, sars-cov-2"
51818,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.088235294,"is, bat, in"
51819,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.088235294,"a, for, the, on, of, sequence"
51820,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.088235294,"a, of, revealed, that, with, the"
51821,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.088235294,"the, of, to, a, and, viruses"
51822,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.088235294,"in, a, of, to, that, quite"
51823,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.088235294,"hosts, sars-cov-2, are"
51824,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.088235294,"of, sars-, likely"
51825,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.088235294,"a, be, coronavirus, bat, that, bats"
51826,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.088235294,"et, which, that, may, as, to"
51827,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.088235294,"coronavirus, is, and, from, to, in"
51828,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.088235294,"is, a, which, bat, in, from"
51829,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.088235294,"to, in, and, that, bats, be"
51830,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.088235294,"the, of, that, sars-cov-2, and, a"
51831,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.088235294,"that, sars-cov-2, a, the, of, at"
51832,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.088235294,"a, common, share, sars-cov-2, the, and"
51833,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.088235294,"as, et, to, which, that, may"
51834,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.088235294,"as, the, of, to, et, that"
51835,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.088235294,"the, pangolin, is"
51836,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.088235294,"to, pangolin, the"
51837,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.088235294,"the, research, sars-cov-2"
51838,"t some virus detected in pangolins 

were capable of infecting humans.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.088235294,"virus, of, humans."
51839,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.088235294,"he, to, and"
51840,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.088235294,"human, of, the"
51841,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.088235294,"sars-cov-2, are, with"
51842,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.088235294,"the, have, at"
51843,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.088235294,"the, have, in"
51844,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.088235294,"the, yunnan, bat"
51845,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.088235294,"in, related, closely"
51846,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.088235294,"sars-cov-2, viruses, in"
51847,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.088235294,"the, of, at"
51848,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.088235294,"of, at, the"
51849,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.088235294,"between, and, a"
51850,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.088235294,"sars-cov-2, a, pangolin"
51851,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.088235294,"a, of, the, that, and, in"
51852,"bats are also important reservoir species for a great 

range of coronaviruses","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.088235294,"for, a, of"
51853,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.088235294,"has, natural, the"
51854,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.088235294,"the, has, of"
51855,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.088235294,"in, the, for"
51856,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.088235294,"the, sars-cov-2, of, natural, origin, and"
51857,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.088235294,"in, of, to, the, which, this, closely, related, virus"
51858,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.088235294,"the, animals, to"
51859,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.088235294,"in, all, previous"
51860,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.088235294,"the, of, and, a, viruses, to"
51861,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.088235294,"the, and, a, to, these, of"
51862,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.088235294,"the, are, found"
51863,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.088235294,"the, a, bat"
51864,"Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.088235294,"viruses, sars-cov-2, in"
51865,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.088235294,"of, in, wild, for, the, to"
51866,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.088235294,"the, to, bat, coronavirus, and, that, high, but, not"
51867,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.088235294,"yunnan, the, bat"
51868,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.088235294,"coronaviruses, of, viruses"
51869,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.088235294,"not, that, the"
51870,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.088235294,"the, sars-cov-2, into"
51871,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.088235294,"research, the, sars-cov-2"
51872,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.088235294,"to, see, for, the, of, that"
51873,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.088235294,"the, to, with, of, for, and"
51874,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.088235294,"that, the, of, sars-cov-2, and, a"
51875,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.088235294,"the, of, to, a, bats, with, that, in, is"
51876,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.088235294,"is, to, the, that, from, an"
51877,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.088235294,"the, were, and, in, of, from, coronaviruses, genome, identity"
51878,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.088235294,"virus, sars-cov-2, in"
51879,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.088235294,"the, to, virus"
51880,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.088235294,"the, with, identity"
51881,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.088235294,"a, the, of, that, not, is"
51882,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.088235294,"the, of, is, by, a, that"
51883,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.088235294,"the, that, zoonotic, of, a, by"
51884,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.088235294,"from, an, to"
51885,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.088235294,"sars-cov-2, from, in"
51886,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.088235294,"the, with, bat"
51887,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.088235294,"with, of, sequence"
51888,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.088235294,"with, of, 2019"
51889,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.088235294,"of, with, that"
51890,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.088235294,"sequence, of, that"
51891,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).",0.088235294,"to, sars-cov-2, a, of, in, the, and, it, been, that, furin, cleavage, site, with, coronaviruses"
51892,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.088235294,"coronavirus, that, to"
51893,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.088235294,"at, to, from, in, the, by, one, and, horseshoe"
51894,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.088235294,"in, amino, acid"
51895,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.088235294,"to, the, and, natural, is, be"
51896,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.088235294,"the, of, et, that, as, to"
51897,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.088235294,"these, to, the, and, that, be"
51898,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.088235294,"of, the, in, a, that, animal"
51899,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.088235294,"amino, acids, the, in, to, that"
51900,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.088235294,"by, the, of, species, to, and, also, it, for"
51901,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.088235294,"a, the, from"
51902,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.088235294,"the, to, zoonotic"
51903,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.088235294,"live, in, to"
51904,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.088235294,"was, from, that"
51905,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.088235294,"bat, in, sars-cov-2"
51906,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.088235294,"found, in, with"
51907,"The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.088235294,"the, of, furin, cleavage, in, a, been, coronaviruses, to, and, sars-cov-2, it, that, site, with"
51908,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.088235294,"reservoir, not, for, the, of, infect"
51909,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.088235294,"the, have, population, animal, to, and"
51910,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.088235294,"the, to, bat, serve, as, reservoir"
51911,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",Coronaviruses account for over 30% of the world’s viruses.,0.088235294,"the, for, over"
51912,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.088235294,"that, sars-cov-2, related"
51913,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.088235294,"coronaviruses, are, including"
51914,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.088235294,"other, and, virus"
51915,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.088235294,"the, for, virus"
51916,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.088235294,"and, in, an"
51917,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.088235294,"the, to, in, a, of, as, viruses, that, multiple"
51918,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.088235294,"that, of, bats, to, is, a, in, with, the"
51919,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.088235294,"a, of, common"
51920,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.088235294,"when, to, the"
51921,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.088235294,"the, similarity, sars-cov-2"
51922,"Those who eagerly peddle suggestions of 

laboratory involvement have consistently failed to present 

credible arguments to support their positions.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.088235294,"of, have, to"
51923,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.088235294,"of, with, than"
51924,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","This suggests that the BANAL series may be able to directly infect  

humans.",0.088235294,"the, that, this"
51925,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","This suggests that the BANAL series may be able to directly infect  

humans.",0.088235294,"that, suggests, be"
51926,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","This suggests that the BANAL series may be able to directly infect  

humans.",0.088235294,"this, the, that"
51927,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.088235294,"viruses, to, that"
51928,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.088235294,"in, of, more"
51929,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.088235294,"he, of, the"
51930,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.088235294,"have, at, the"
51931,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.088235294,"sars-cov-2, the, covid-19"
51932,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.088235294,"virus, in, sars-cov-2"
51933,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.088235294,"the, sars-cov-2, and, share, a, common"
51934,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.088235294,"the, is, and, be, in, that"
51935,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.088235294,"the, and, that, covid-19, in, is, sars-cov-2, be, infected"
51936,"In the 

case of MERS, dromedaries were the principal host.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.088235294,"in, the, case"
51937,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.088235294,"the, were, that"
51938,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.088235294,"the, of, that, were, wuhan, covid-19"
51939,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.088235294,"on, and, with, to, a, by"
51940,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.088235294,"to, have, occurred, with, the, of, into, virus, human"
51941,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.088235294,"the, of, to, human, a, or, that, this, not"
51942,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.088235294,"the, market, that, to, of, transmission"
51943,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.088235294,"a, of, the, with, that, revealed"
51944,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.088235294,"that, the, of, were, in, to, a, and, market"
51945,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.088235294,"of, a, virus, the, from, taken"
51946,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.088235294,"a, for, as, the, of, and, in, with, that, to, an, host"
51947,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.088235294,"when, the, in, that, more, than"
51948,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.088235294,"the, that, in, a, genome, as, to, from, humans"
51949,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.088235294,"the, an, to, identical, that, of, and, from, horseshoe"
51950,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.088235294,"to, be, a, that, from, bats, and, the, as"
51951,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.088235294,"the, of, coronaviruses, from, and, were, in, identity, genome"
51952,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.088235294,"the, of, to, species, it, also, for, and, by"
51953,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.088235294,"this, in, the, of, which, closely, related, to, virus"
51954,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.088235294,"at, the, and, in, horseshoe, from, one, to, by"
51955,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.088235294,"several, in, southern, china, and, by, chinese, were, for"
51956,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.088235294,"and, also, a, of, in, an, the, for, to"
51957,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.088235294,"animal, reservoir, to, a, are, as, likely, and, in"
51958,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.088235294,"that, the, of, multiple, in, as, viruses, a, to"
51959,"with the first case being linked to  

a seafood market","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.088235294,"with, the, case, to, a, market"
51960,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.088235294,"the, earliest, cases, market., with, were"
51961,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.088235294,"the, reported, to, in, with, of"
51962,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.088235294,"in, is, that, the, covid-19, be, and, sars-cov-2, infected"
51963,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.088235294,"sars-cov-2, is, a, that, with, infected, to, the, for"
51964,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.088235294,"this, is, sars-cov-2, and, to, the, between, that, in"
51965,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.088235294,"in, contrast,, the, of, is, to, sars-cov-2, at, that"
51966,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.088235294,"in, which, to, of, on, and"
51967,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.088235294,"that, the, of, and, is, but"
51968,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.088235294,"in, the, and, are, that, these"
51969,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.088235294,"be, that, a, of, sars-cov-2, by"
51970,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.088235294,"the, that, of, zoonotic, by, a"
51971,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.088235294,"the, and, all, of, that, to"
51972,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.088235294,"the, to, that, of, and, from"
51973,Coronaviruses account for over 30% of the world’s viruses.,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.088235294,"for, over, the"
51974,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.088235294,"with, the, for, a, to, that, is, sars-cov-2, infected"
51975,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Those who eagerly peddle suggestions of 

laboratory involvement have consistently failed to present 

credible arguments to support their positions.",0.088235294,"have, of, to"
51976,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","unnatural origin of SARS-CoV-2, but these people are 

simply wrong",0.088235294,"of, people, origin"
51977,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.088235294,"from, that, sars-cov-2, and, in, were"
51978,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.088235294,"to, in, china"
51979,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.088235294,"sars-cov-2, found, to"
51980,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.088235294,"the, from, also"
51981,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.088235294,"host, animal, was"
51982,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.088235294,"in, humans, and"
51983,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.088235294,"has, an, and"
51984,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.088235294,"and, in, sars-cov-2"
51985,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.088235294,"not, a, that"
51986,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.088235294,"the, that, to, most, is, of, or, not, sars-cov-2"
51987,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.088235294,"this, that, a, the, human, or, of, not, to"
51988,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.088235294,"of, that, a"
51989,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.088235294,"a, is, that"
51990,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.088235294,"a, coronavirus, that"
51991,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.088235294,"that, related, sars-cov-2"
51992,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.088235294,"of, a, sars-cov-2"
51993,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.088235294,"related, a, is"
51994,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.088235294,"of, that, sars-cov-2"
51995,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.088235294,"the, had, of"
51996,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.088235294,"available, the, of"
51997,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.088235294,"the, genetic, of"
51998,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.088235294,"is, to, its"
51999,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.088235294,"serve, as, the, reservoir, to, bat"
52000,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.088235294,"of, the, bat, sars-, cov-2, as"
52001,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.088235294,"the, sars-cov-2,, in, spike, that, a"
52002,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.088235294,"in, the, that, coronaviruses, to, for"
52003,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.088235294,"to, that, the, of, for, sars-cov-2"
52004,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.088235294,"that, of, is, in, sars-cov-2, the"
52005,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.088235294,"not, do, of, and, the, including"
52006,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.088235294,"in, that, the, is, related, of"
52007,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.088235294,"is, and, from, to, coronavirus, in"
52008,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.088235294,"and, the, to, but, not, high, that, bat, coronavirus"
52009,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.088235294,"one, coronavirus, a, and, to, the"
52010,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.088235294,"a, of, the, that, covid-19, analysis"
52011,hese close genetic relations suggest that they all have their ecological origin in bat populations,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.088235294,"that, their, bat"
52012,"preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.088235294,"that, of, their"
52013,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.088235294,"identity, in, of"
52014,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.088235294,"evidence, that, and"
52015,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.088235294,"indicates, that, the"
52016,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",The COVID-19 most likely developed from bat origin coronaviruses,0.088235294,"most, the, from"
52017,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.088235294,"a, the, of, or, as, intermediate"
52018,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.088235294,"of, is, a"
52019,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.088235294,"in, the, and, to, that, of"
52020,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.088235294,"of, viruses, coronaviruses"
52021,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.088235294,"of, a, common"
52022,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.088235294,"in, are, to"
52023,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.088235294,"to, in, animals"
52024,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.088235294,"transmitted, to, in"
52025,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.088235294,"through, to, most"
52026,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.088235294,"have, the, in"
52027,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.088235294,"the, of, by"
52028,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.088235294,"the, in, covid-19"
52029,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.088235294,"the, of, china, in, market, were"
52030,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.088235294,"of, with, to, reported, the, in"
52031,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.088235294,"have, in, bats"
52032,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.088235294,"that, there, is"
52033,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.088235294,"is, all, the"
52034,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.088235294,"bats, the, or, of, transmission, and"
52035,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.088235294,"and, to, be, of, in, other"
52036,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.088235294,"to, the, scenario"
52037,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.088235294,"the, was, found"
52038,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.088235294,"a, and, of, virus, from, bat"
52039,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.088235294,"in, to, bats"
52040,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.088235294,"to, live, in"
52041,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.088235294,"contact, and, to, species, be, by"
52042,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.088235294,"by, a, and, to, on, with"
52043,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.088235294,"sars-cov, and, in, to, of, which"
52044,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.088235294,"the, of, sars-cov, and, identical, to"
52045,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.088235294,"the, of, were, market, in, china"
52046,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.088235294,"sars-cov-2, of, the, and, viruses, in"
52047,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","t some virus detected in pangolins 

were capable of infecting humans.",0.088235294,"of, virus, in"
52048,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.088235294,"in, chinese, for, by, southern, china, were, several, and"
52049,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.088235294,"on, the, virus, as, a, that, with, and, to"
52050,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.088235294,"in, the, by"
52051,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.088235294,"pangolins, in, an"
52052,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.",0.088235294,"their, that, of"
52053,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.088235294,"covid-19, is, the"
52054,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.088235294,"is, from, which"
52055,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.088235294,"is, a, related"
52056,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.088235294,"animals, from, to, and, the, species"
52057,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.088235294,"the, a, zoonotic, to, of, and"
52058,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.088235294,"including, the, and, do, not, of"
52059,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.088235294,"the, of, and, that, jumped, humans"
52060,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.088235294,"bat, cov, sars-cov-2"
52061,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.088235294,"the, to, coronavirus, and, a, one"
52062,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.088235294,"bats, the, on"
52063,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","zoonotic corona- 

viruses have become an increasing threat to human health,",0.088235294,"human, to, viruses"
52064,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.088235294,"the, of, and, to, for, virus"
52065,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.088235294,"of, genomic, analysis"
52066,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.088235294,"likely, of, sars-"
52067,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.088235294,"was, more, likely"
52068,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.088235294,"the, a, that, are, to, at"
52069,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.088235294,"that, to, at, the, by, a, of, has, been"
52070,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.088235294,"the, that, are, also, of, or"
52071,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.088235294,"animal, are, the"
52072,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.088235294,"bats,, the, in"
52073,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.088235294,"in, the, bats,"
52074,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.088235294,"a, to, is"
52075,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.088235294,"in, to, that, sars-cov-2, as, they"
52076,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.088235294,"of, a, reservoir"
52077,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.088235294,"of, the, yet"
52078,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.088235294,"the, been, origin."
52079,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.088235294,"he, the, of"
52080,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.088235294,"the, not, been"
52081,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.088235294,"other, the, and"
52082,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.088235294,"not, been, the"
52083,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.088235294,"have, that, sars-cov-2, to, as, the"
52084,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.088235294,"of, a, the, was, by, from"
52085,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.088235294,"the, reservoir, for, of, infect, not"
52086,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.088235294,"the, from, zoonotic"
52087,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.088235294,"likely, an, animal"
52088,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.088235294,"the, was, as"
52089,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.088235294,"in, that, has"
52090,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.088235294,"been, animal, in"
52091,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.088235294,"the, genome, sars-cov-2"
52092,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.088235294,"to, sars-cov-2, found"
52093,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.088235294,"was, found, the"
52094,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.088235294,"sars-cov-2, the, to"
52095,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.088235294,"authors, as, also, the, of, they"
52096,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.088235294,"of, the, also, are, that, or"
52097,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.088235294,"the, of, and, a, human, as"
52098,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.088235294,"of, to, is, in, sars-cov-2, the"
52099,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.088235294,"by, in, the, is, to, of"
52100,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.088235294,"the, and, has, in, to, of"
52101,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.088235294,"is, a, from, bat, which, in"
52102,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.088235294,"has, and, an"
52103,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.088235294,"to, sars-cov-2, from"
52104,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.088235294,"sars-cov-2, and, from"
52105,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.088235294,"that, was, and"
52106,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.088235294,"from, that, was"
52107,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.088235294,"that, sars-cov-2, are"
52108,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.088235294,"sars-cov-2, of, that, to, coronaviruses, sequences"
52109,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.088235294,"on, and, to, of, which, in"
52110,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.088235294,"genome, bat, of"
52111,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.088235294,"of, with, bat"
52112,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.088235294,"that, evidence, from"
52113,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.088235294,"from, the, that"
52114,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.088235294,"be, that, the"
52115,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.088235294,"that, from, to, an, is, the"
52116,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.088235294,"by, from, that, the, is, to"
52117,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.088235294,"the, and, has, to, that, but"
52118,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.088235294,"genetic, of, the"
52119,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.088235294,"in, animals, to"
52120,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.088235294,"that, a, naturally, occurring, the, is"
52121,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.088235294,"sars-, cov-2, most"
52122,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.088235294,"evidence, the, and, that, of, to"
52123,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.088235294,"the, that, its"
52124,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.088235294,"the, bats, on"
52125,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.088235294,"are, and, bats"
52126,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.088235294,"analysis, that, the"
52127,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.088235294,"genome, of, the, virus, from, in"
52128,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.088235294,"the, in, related, that, of, is"
52129,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.088235294,"by, in, to, the, of, is"
52130,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.088235294,"is, to, the, that, by, from"
52131,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.088235294,"a, reservoir, bats"
52132,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.088235294,"for, to, the"
52133,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.088235294,"the, to, which, of, for, and"
52134,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.088235294,"the, of, viral, sars-cov-2, and, similarity"
52135,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.088235294,"an, to, a, in, for, the, of, and, also"
52136,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.088235294,"although, with, sars-cov-2"
52137,"Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.088235294,"they, could, be"
52138,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.088235294,"with, sars-cov-2, are"
52139,"This suggests that the BANAL series may be able to directly infect  

humans.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.088235294,"suggests, that, be"
52140,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.088235294,"an, in, pangolins"
52141,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.088235294,"are, in, sars-cov-2"
52142,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.088235294,"the, that, to, have, are, by, of, and, sars-cov-2"
52143,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.088235294,"a, that, the, receptor, and, by"
52144,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.088235294,"a, sars-cov-2,, spike, in, the, that"
52145,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.088235294,"sars-cov-2, have, the"
52146,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.088235294,"as, to, the"
52147,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.088235294,"in, the, of, a, that, and"
52148,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.088235294,"and, the, sars, mers, of, bat"
52149,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.088235294,"the, of, sars-, cov-2, bat, as"
52150,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.088235294,"and, be, to, that, in, bats"
52151,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.088235294,"these, and, the, to, be, that"
52152,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.088235294,"the, is, and, in, that, to"
52153,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.088235294,"the, and, to, that, in, this, is, between, sars-cov-2"
52154,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.088235294,"the, that, in, is, this, origin"
52155,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.088235294,"that, as, to, sars-cov-2, they, in"
52156,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.088235294,"the, of, this"
52157,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.088235294,"origin, of, the"
52158,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.088235294,"in, the, when, that, more, than"
52159,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.088235294,"further, the, for"
52160,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.088235294,"bat, has, origin"
52161,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.088235294,"sars-cov-2, cov, the"
52162,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.088235294,"more, the, than"
52163,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.088235294,"the, indicates, that"
52164,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.088235294,"the, same, also"
52165,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.088235294,"the, and, zc45, bat, are, but"
52166,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.088235294,"that, sars-cov-2, this"
52167,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.088235294,"in, bats, sars-cov-2"
52168,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.088235294,"in, that, this"
52169,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.088235294,"the, that, are, to, and, for"
52170,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.088235294,"that, sars-cov-2, sars-, cov-2, and, to"
52171,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.088235294,"to, sars-cov-2, the, that, for, of"
52172,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.088235294,"with, that, sars-cov-2"
52173,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.088235294,"the, sars-cov-2, to, with, of, and"
52174,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.088235294,"of, the, by"
52175,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.088235294,"in, the, of, and, we, for"
52176,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.088235294,"that, the, sars-cov-2, in, of, and"
52177,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.088235294,"the, sars-cov-2, similarity"
52178,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.088235294,"sars-cov-2, are, in"
52179,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.088235294,"virus, for, the"
52180,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.088235294,"the, of, to, that, in, is, sars-cov-2, contrast,, at"
52181,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.088235294,"as, sars-cov-2, the"
52182,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.088235294,"sars-cov-2, be, of, the, to, virus"
52183,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.088235294,"with, from, zoonotic"
52184,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.088235294,"a, of, the, from, by, zoonotic"
52185,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.088235294,"origin, the, in"
52186,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.088235294,"was, the, in"
52187,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.088235294,"that, the, for"
52188,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.088235294,"bat, the, sars-cov-2."
52189,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.088235294,"from, that, be"
52190,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.088235294,"in, bat, coronaviruses"
52191,hese close genetic relations suggest that they all have their ecological origin in bat populations,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.088235294,"close, in, bat"
52192,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.088235294,"of, that, a, in, quite, to"
52193,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.088235294,"that, in, bats, and, to, a"
52194,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.088235294,"to, and, of, that, related, in"
52195,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.088235294,"with, found, in"
52196,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.088235294,"that, a, naturally, the, of, to"
52197,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.088235294,"in, a, of, animal, that, the"
52198,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.088235294,"that, to, the, amino, acids, in"
52199,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.088235294,"to, from, and, the, of, sars-cov-2"
52200,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.088235294,"the, that, sars-cov-2, natural, and, from"
52201,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.088235294,"that, the, from, in, to, and"
52202,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.088235294,"is, in, bat"
52203,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.088235294,"in, the, of, to, sequence, than"
52204,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.088235294,"of, are, coronaviruses, and, common, in"
52205,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.088235294,"the, of, to, a, and, these"
52206,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.088235294,"and, in, to, the, of, has"
52207,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.088235294,"to, the, that, has, and, but"
52208,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.088235294,"bat, and, zc45, the, but, are"
52209,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.088235294,"of, and, related, to, that, in"
52210,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.088235294,"the, of, closely, related, is, to"
52211,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.088235294,"and, viruses, of, natural, the, virus"
52212,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.088235294,"to, sars-cov-2, the, virus, be, of"
52213,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.088235294,"the, bat, sars-cov-2."
52214,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.088235294,"is, a, the"
52215,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.088235294,"the, analysis, that"
52216,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).",0.088082902,"and, the, of, also, appears, to, as, a, different, with, new, infect, other, that, in, can, is"
52217,"The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.088082902,"the, of, is, in, a, different, to, infect, and, that, appears, with, can, also, other, as, new"
52218,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.088,"we, and, of, the, animals, in, but, were, not, found, that"
52219,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.088,"the, of, and, in, we, found, animals, that, not, were, but"
52220,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.088,"that, by, a, of, with, one, to, and, the, intermediate, for"
52221,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.088,"the, of, a, to, live, in, and, virus, at, was, isolated"
52222,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.088,"the, from, on, and, were, in, all, of, to, that, positive"
52223,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.088,"the, was, to, a, live, virus, and, in, of, isolated, at"
52224,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.088,"on, in, the, and, that, of, positive, were, to, all, from"
52225,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.088,"a, of, the, and, by, to, with, for, one, that, intermediate"
52226,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.087912088,"of, which, to, human, virus, have, and, the"
52227,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.087912088,"to, have, the, of, and, which, virus, human"
52228,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.087912088,"had, to, a, in, the, virus, and, bats,"
52229,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.087912088,"the, and, of, to, infections, sars-cov-2, animal, be"
52230,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.087912088,"that, had, a, the, virus, was, did, not"
52231,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.087912088,"the, viruses, to, more, closely, related, in, than"
52232,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.087912088,"the, that, was, in, than, and, sars-cov-2, at"
52233,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.087912088,"the, of, and, in, viruses, are, to, sars-cov-2,"
52234,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.087912088,"viruses, in, more, closely, related, to, the, than"
52235,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.087912088,"the, sars-cov-2, at, was, than, that, in, and"
52236,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.087912088,"the, of, is, more, closely, related, to, than"
52237,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.087912088,"a, team, of, the, found, that, covid-19, were"
52238,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.087912088,"not, do, a, of, have, the, to, animals"
52239,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.087912088,"and, the, to, animal, in, had, sars-cov, that"
52240,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.087912088,"from, the, for, first, time, to, a, virus"
52241,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.087912088,"the, of, in, to, sars, bats, also, coronaviruses"
52242,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.087912088,"from, the, also, to, sars, in, of, isolated"
52243,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.087912088,"in, a, on, was, that, were, and, market"
52244,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.087912088,"in, the, of, and, are, to, viruses, sars-cov-2,"
52245,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.087912088,"than, the, animals, was, to, by, a, coronavirus"
52246,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.087912088,"the, to, and, sars-cov, that, had, in, animal"
52247,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.087912088,"for, and, with, to, the, in, of, a"
52248,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.087912088,"the, sars, bats, as, reservoirs, for, and, of"
52249,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.087912088,"the, and, for, to, were, in, sars, other"
52250,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.087912088,"a, is, to, its, in, the, which, that"
52251,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.087912088,"the, in, joint, to, by, and, with, a"
52252,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.087912088,"a, team, of, the, that, covid-19, were, found"
52253,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.087912088,"did, not, a, that, the, virus, was, had"
52254,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.087912088,"the, coronavirus, was, to, by, animals, than, a"
52255,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.087912088,"the, first, was, in, that, as, animal, for"
52256,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.087912088,"in, into, and, with, this, that, the, sars"
52257,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.087912088,"bats, as, the, reservoirs, for, of, sars, and"
52258,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.087912088,"the, of, sars, in, also, to, coronaviruses, bats"
52259,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.087912088,"a, virus, from, to, for, the, first, time"
52260,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.087912088,"the, of, sars, in, also, to, isolated, from"
52261,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.087912088,"a, the, to, in, bats,, had, virus, and"
52262,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.087912088,"that, was, and, in, were, a, market, on"
52263,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.087912088,"the, presence, in, of, to, that, was, virus"
52264,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.087912088,"in, the, of, for, to, with, and, a"
52265,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.087912088,"and, a, of, in, an, the, for, to"
52266,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.087912088,"in, by, a, joint, with, and, to, the"
52267,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.087912088,"the, animal, of, sars-cov-2, infections, and, be, to"
52268,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.087912088,"the, for, sars, and, other, to, were, in"
52269,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.087912088,"the, to, a, that, in, which, is, its"
52270,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.087912088,"the, to, in, of, presence, was, that, virus"
52271,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.087912088,"the, of, to, animals, not, do, have, a"
52272,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.087912088,"from, intermediate, and, to, the, sars-cov-2, in, a"
52273,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.087912088,"from, a, and, sars-cov-2, intermediate, to, in, the"
52274,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.087912088,"the, to, a, of, sars, that, virus, and"
52275,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.087912088,"for, and, an, to, the, in, of, a"
52276,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.087912088,"the, and, that, into, in, sars, this, with"
52277,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.087912088,"in, the, first, animal, that, for, as, was"
52278,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.087912088,"the, to, more, closely, related, is, than, of"
52279,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.087719298,"the, large, of, that, in"
52280,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.087719298,"the, in, from, of, a"
52281,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.087719298,"the, from, that, a, and"
52282,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.087719298,"very, to, bat, and, related"
52283,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.087719298,"many, human, are, and, in"
52284,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.087719298,"the, of, and, have, animal"
52285,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.087719298,"that, of, were, with, and"
52286,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.087719298,"of, than, that, virus, or"
52287,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.087719298,"virus, that, with, infected, for"
52288,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.087719298,"of, sars-cov, and, in, to"
52289,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.087719298,"of, bats, to, in, sars-cov-2"
52290,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.087719298,"bats, more, of, and, sequences"
52291,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.087719298,"in, the, of, bats, are"
52292,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.087719298,"to, and, have, the, which"
52293,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.087719298,"virus, into, with, to, the"
52294,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.087719298,"the, of, to, which, virus"
52295,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.087719298,"with, the, of, work, is"
52296,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.087719298,"of, to, a, was, in"
52297,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.087719298,"sars-cov-2, have, be, a, of"
52298,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.087719298,"been, a, of, that, by"
52299,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.087719298,"the, of, sars-cov-2, to, it"
52300,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.087719298,"the, of, coronaviruses, from, sars-cov-2"
52301,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.087719298,"would, the, that, sars-cov-2, from"
52302,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.087719298,"be, a, of, sars-cov-2, have"
52303,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.087719298,"have, sars-cov-2, to, bat, the"
52304,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.087719298,"human, in, to, the, other"
52305,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.087719298,"the, to, in, and, naturally"
52306,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.087719298,"of, the, spike, in, a"
52307,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.087719298,"between, sars-cov-2, and, of, the, have, to, in, found, bat"
52308,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.087719298,"the, of, a, human, and"
52309,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.087719298,"the, sars-cov-2, from, in, is"
52310,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.087719298,"by, genetic, is, sars-cov-2, the"
52311,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.087719298,"a, sequence, was, from, in"
52312,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.087719298,"to, are, and, coronaviruses, bat"
52313,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.087719298,"the, sars-cov-2, have, to, bat"
52314,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.087719298,"are, a, the, of, and"
52315,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.087719298,"and, more, that, of, intermediate"
52316,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.087719298,"of, and, similar, species,, in"
52317,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.087719298,"in, similar, of, receptor, protein"
52318,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.087719298,"and, of, that, similar, in"
52319,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.087719298,"to, the, in, of, and"
52320,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.087719298,"can, that, to, and, the"
52321,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.087719298,"have, the, of, to, and"
52322,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.087719298,"and, have, the, origin, sars-cov-2"
52323,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.087719298,"other, mammals, of, and, bats"
52324,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.087719298,"to, ace2, receptor, in, host"
52325,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.087719298,"the, in, that, as, for"
52326,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.087719298,"the, was, to, thus, and"
52327,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.087719298,"sequence, that, the, and, similarity"
52328,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.087719298,"that, the, similarity, and, a"
52329,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.087719298,"large, of, that, the, in"
52330,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.087719298,"of, in, is, the, to"
52331,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.087719298,"the, of, and, coronavirus, a"
52332,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.087719298,"the, can, to, that, and"
52333,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.087719298,"of, shares, with, sars-cov-2, the"
52334,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.087719298,"the, from, wuhan, was, to"
52335,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.087719298,"and, humans, was, in, the"
52336,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.087719298,"is, sars-cov-2, from, the, in"
52337,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.087719298,"even, of, the, in, bats"
52338,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.087719298,"a, the, and, in, that"
52339,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.087719298,"the, been, a, that, by"
52340,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.087719298,"on, that, sars-cov-2, through, and"
52341,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.087719298,"and, are, bat, coronaviruses, to"
52342,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.087719298,"studies, and, have, from, bat"
52343,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.087719298,"to, a, and, been, transmitted"
52344,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.087719298,"coronaviruses, from, and, in, sars-cov-2"
52345,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.087719298,"been, bat, and, sars-cov-2, a"
52346,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.087719298,"sars-cov-2, a, been, in, animal"
52347,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.087719298,"to, the, of, that, a"
52348,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.087719298,"nucleotide, that, the, sars-cov-2, and"
52349,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.087719298,"studies, that, the, sars-cov-2, and"
52350,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.087719298,"have, from, studies, and, bat"
52351,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.087719298,"were, by, in, the, their"
52352,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.087719298,"in, which, were, of, their"
52353,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.087719298,"the, of, most, from, humans"
52354,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.087719298,"sars-cov-2, and, be, to, that"
52355,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.087719298,"and, in, the, of, animal"
52356,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.087719298,"early, in, the, of, and"
52357,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.087719298,"to, the, in, that, a"
52358,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.087719298,"in, are, more, to, that"
52359,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.087719298,"the, a, of, from, by"
52360,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.087719298,"the, of, animal, and, in"
52361,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.087719298,"the, of, coronavirus, from, and"
52362,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.087719298,"of, the, from, animal, hosts"
52363,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.087719298,"been, of, and, the, hosts"
52364,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.087719298,"the, to, in, other, human"
52365,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.087719298,"that, the, reservoir, and, in"
52366,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.087719298,"the, mers-cov, that, likely, and"
52367,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.087719298,"sars-cov-2, from, to, and, in"
52368,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.087719298,"that, and, to, than, the"
52369,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.087719298,"sars-cov-2, in, including, and, from"
52370,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.087719298,"be, the, with, that, could"
52371,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.087719298,"collected, on, were, the, market."
52372,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.087719298,"on, the, that, could, be"
52373,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.087719298,"in, the, a, to, as, genome, that, events, from, it"
52374,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.087719298,"this, that, were, from, in, the, market, a, of, are"
52375,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.087719298,"that, were, in, the, a, at, animals, and, of, on"
52376,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.087719298,"to, in, that, a, covid-19"
52377,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.087719298,"the, of, that, was, outbreak"
52378,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.087719298,"all, that, have, other, animals"
52379,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.087719298,"the, of, to, that, for"
52380,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.087719298,"coronaviruses, and, a, to, of"
52381,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.087719298,"that, of, all, and, have"
52382,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.087719298,"have, animals, all, other, that"
52383,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.087719298,"of, natural, the, and, in"
52384,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.087719298,"of, and, that, were, with"
52385,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.087719298,"of, that, the, a, high"
52386,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.087719298,"such, as, to, they, in"
52387,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.087719298,"et, al., of, the, in"
52388,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.087719298,"the, is, coronavirus, has, that"
52389,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.087719298,"that, the, as, a, to"
52390,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.087719298,"the, from, and, of, sars-cov-2"
52391,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.087719298,"the, of, and, their, to"
52392,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.087719298,"with, the, sars-cov-2, bat, ratg13"
52393,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.087719298,"sars-cov-2, a, and, to, that"
52394,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.087719298,"the, have, animal, of, and"
52395,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.087719298,"and, by, the, was, of"
52396,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.087719298,"of, and, by, suggesting, the"
52397,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.087719298,"is, sars-cov-2, the, of, on"
52398,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.087719298,"the, and, to, a, in"
52399,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.087719298,"and, a, to, the, bats"
52400,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.087719298,"the, a, from, to, and"
52401,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.087719298,"the, bats, a, from, and"
52402,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.087719298,"to, a, in, through, and"
52403,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.087719298,"virus, from, in, at, the"
52404,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.087719298,"the, of, that, most, to"
52405,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.087719298,"has, the, in, of, and"
52406,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.087719298,"in, is, the, covid-19, and"
52407,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.087719298,"evidence, a, of, the, that"
52408,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.087719298,"the, and, to, in, naturally"
52409,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.087719298,"that, the, natural, and, in"
52410,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.087719298,"and, reservoirs, to, in, the"
52411,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.087719298,"the, may, to, intermediate, host"
52412,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.087719298,"on, the, natural, and, a"
52413,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.087719298,"a, of, market, with, by, had, the, or, exposure, to"
52414,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.087719298,"to, that, the, bats, sars-cov-2"
52415,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.087719298,"that, the, of, a, was"
52416,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.087719298,"the, or, of, in, china"
52417,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.087719298,"with, the, of, that, or"
52418,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.087719298,"the, that, could, be, with"
52419,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.087719298,"the, of, with, however,, a"
52420,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.087719298,"the, not, that, with, of"
52421,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.087719298,"be, a, the, that, but"
52422,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.087719298,"a, sars-cov-2, and, sars-cov, the"
52423,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.087719298,"the, to, a, and, which"
52424,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.087719298,"the, of, is, animal, to"
52425,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.087719298,"the, of, for, genome, sars-like"
52426,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.087719298,"is, similar, the, of, s"
52427,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.087719298,"to, of, is, similar, bat"
52428,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.087719298,"the, to, and, was, thus"
52429,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.087719298,"the, could, or, to, and"
52430,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.087719298,"as, to, the, of, be"
52431,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.087719298,"the, to, infection, for, which"
52432,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.087719298,"the, that, sequence, similarity, and"
52433,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.087719298,"that, sars-cov-2, nucleotide, and, the"
52434,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.087719298,"et, that, the, and, bat"
52435,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.087719298,"bat, and, have, the, sars-cov-2"
52436,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.087719298,"of, sars-cov-2, recently, to, that"
52437,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.087719298,"the, spike, a, of, in"
52438,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.087719298,"a, the, of, pangolin, as"
52439,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.087719298,"are, the, of, viruses, in"
52440,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.087719298,"in, all, bat, that, origin"
52441,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.087719298,"the, to, or, could, and"
52442,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.087719298,"and, that, of, more, intermediate"
52443,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.087719298,"of, and, by, between, species"
52444,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.087719298,"to, of, the, and, that"
52445,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.087719298,"the, of, covid-19, with, and"
52446,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.087719298,"the, of, and, was, by"
52447,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.087719298,"in, mice, and, human, intestinal"
52448,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.087719298,"in, the, analysis, of, virus"
52449,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.087719298,"are, and, to, zoonotic, that"
52450,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.087719298,"coronaviruses, a, of, to, and"
52451,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.087719298,"and, the, bats, to, a"
52452,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.087719298,"of, the, as, a, pangolin"
52453,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.087719298,"of, the, novel, coronavirus,, and"
52454,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.087719298,"a, the, could, be, to"
52455,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.087719298,"bats, the, natural, of, coronaviruses"
52456,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.087719298,"and, related, to, bat, very"
52457,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.087719298,"the, to, was, from, wuhan"
52458,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.087719298,"the, of, from, and, genome"
52459,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.087719298,"genome, sequence, bat, that, and"
52460,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.087719298,"the, a, that, from, and"
52461,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.087719298,"that, sars-cov-2, through, on, and"
52462,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.087719298,"the, from, and, a, sars-cov-2"
52463,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.087719298,"from, the, that, a, sars-cov-2"
52464,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.087719298,"a, the, on, natural, and"
52465,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.087719298,"a, the, by, that, other"
52466,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.087719298,"the, that, natural, sars-cov-2, laboratory"
52467,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.087719298,"in, to, ace2, receptor, host"
52468,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.087719298,"bat, that, the, et, and"
52469,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.087719298,"and, novel, coronavirus,, the, of"
52470,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.087719298,"that, to, from, and, in"
52471,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.087719298,"in, the, a, from, that"
52472,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.087719298,"the, of, between, and, sars-cov-2"
52473,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.087719298,"a, the, sars-cov-2, and, sars-cov"
52474,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.087719298,"in, that, sars-cov-2, is, bat"
52475,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.087719298,"from, in, that, is, sars-cov-2"
52476,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.087719298,"the, most, likely, of, intermediate"
52477,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.087719298,"and, the, of, that, sars-cov-2"
52478,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.087719298,"sars-cov, and, in, to, of"
52479,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.087719298,"the, sequences, and, bat, of"
52480,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.087719298,"the, and, sars-cov-2, of, are"
52481,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.087719298,"bats, are, hosts, of, to"
52482,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.087719298,"the, results, provide, that, for"
52483,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.087719298,"that, to, be, sars-cov-2, and"
52484,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.087719298,"a, to, that, sars-cov-2, and"
52485,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.087719298,"a, in, and, to, which"
52486,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.087719298,"a, the, that, similarity, and"
52487,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.087719298,"studies, that, sars-cov-2, and, the"
52488,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.087719298,"and, revealed, that, the, of"
52489,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.087719298,"of, which, a, common, sars-cov-2"
52490,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.087719298,"the, similarity, of, that, as"
52491,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.087719298,"the, of, sars-cov, and, both"
52492,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.087719298,"to, be, the, is, likely"
52493,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.087719298,"the, has, identified, a, from"
52494,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.087719298,"been, transmitted, to, a, and"
52495,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.087719298,"the, is, has, a, that"
52496,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.087719298,"of, a, to, that, in"
52497,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.087719298,"with, the, sars-cov-2, of, are"
52498,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.087719298,"the, of, and, an, unknown"
52499,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.087719298,"that, be, transmission, to, the"
52500,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.087719298,"was, the, in, a, of"
52501,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.087719298,"the, in, horseshoe, from, to"
52502,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.087719298,"a, of, the, that, scientific"
52503,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.087719298,"sars-cov-2, of, natural, the, and"
52504,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.087719298,"analysis, of, the, virus, in"
52505,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.087719298,"the, of, to, have, and"
52506,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.087719298,"have, the, and, of, to"
52507,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.087719298,"a, to, the, which, human"
52508,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.087719298,"of, a, and, the, in"
52509,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.087719298,"of, the, and, zoonotic, in"
52510,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.087719298,"and, the, of, to, sars-cov-2"
52511,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.087719298,"in, to, of, sars-cov-2, and"
52512,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.087719298,"the, bats, and, from, a"
52513,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.087719298,"the, genome, of, sars-like, for"
52514,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.087719298,"the, between, sars-cov-2, and, have, to, of, found, in, bat"
52515,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.087719298,"as, the, to, be, of"
52516,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.087719298,"to, the, of, no, that"
52517,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.087719298,"the, more, of, in, and"
52518,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.087719298,"sars-cov-2, the, of, shares, with"
52519,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.087719298,"the, sars-cov-2, in, homology, with"
52520,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.087719298,"from, the, to, a, that, with, in, of, coronavirus, an"
52521,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.087719298,"the, sars-cov-2, sequences, pangolin, of"
52522,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.087719298,"sars-cov-2, from, and, coronaviruses, in"
52523,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.087719298,"the, genome, of, from, and"
52524,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.087719298,"the, two, sequences, in, coronaviruses"
52525,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.087719298,"of, indicated, that, in, a"
52526,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.087719298,"from, identity, with, to, the"
52527,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.087719298,"the, of, and, that, sequence"
52528,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.087719298,"the, and, sars-cov-2, an, to"
52529,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.087719298,"the, in, and, to, from"
52530,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.087719298,"sars-cov-2, the, amino, rbd, with"
52531,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.087719298,"sequence, sars-cov-2, with, the, in"
52532,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.087719298,"the, to, in, from, horseshoe"
52533,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.087719298,"bats, and, the, from, in"
52534,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.087719298,"one, to, from, found, in"
52535,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.087719298,"in, homology, with, sars-cov-2, the"
52536,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.087719298,"that, the, sars-cov-2, and, larger"
52537,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.087719298,"than, the, to, and, that"
52538,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.087719298,"be, to, the, that, transmission"
52539,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.087719298,"the, rbd, amino, with, sars-cov-2"
52540,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.087719298,"suggest, that, the, to, and"
52541,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.087719298,"these, have, in, the, ("
52542,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.087719298,"a, to, the, could, be"
52543,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.087719298,"sars-cov-2, the, of, to, it"
52544,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.087719298,"from, a, intermediate, to, the"
52545,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.087719298,"a, of, the, was, to"
52546,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.087719298,"was, that, the, a, of"
52547,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.087719298,"was, a, and, to, the"
52548,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.087719298,"and, a, of, the, to"
52549,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.087719298,"of, in, the, to, human"
52550,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.087719298,"sars-cov-2, the, and, to, in"
52551,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.087719298,"that, was, the, of, outbreak"
52552,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.087719298,"in, of, that, the, intermediate"
52553,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.087719298,"coronavirus, with, sars-cov-2, to, in"
52554,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.087719298,"evidence, that, the, of, a"
52555,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.087719298,"is, sars-cov-2, at, the, genome"
52556,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.087719298,"the, is, of, covid-19, in"
52557,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.087719298,"the, in, china, or, of"
52558,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.087719298,"in, the, of, more, and"
52559,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.087719298,"are, in, more, the, and"
52560,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.087719298,"and, of, in, the, viral"
52561,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.087719298,"as, the, of, and, to"
52562,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.087719298,"the, of, most, likely, intermediate"
52563,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.087719298,"bat, that, the, sars-cov-2, and"
52564,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.087719298,"important, of, and, to, in"
52565,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.087719298,"and, similar, of, in, species,"
52566,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.087719298,"the, of, and, suggesting, by"
52567,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.087719298,"between, and, of, species, by"
52568,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.087719298,"to, a, that, the, as"
52569,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.087719298,"the, covid-19, of, a, to"
52570,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.087719298,"to, in, the, same, bat"
52571,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.087719298,"of, sars-cov-2, which, a, common"
52572,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.087719298,"as, the, is, to, sars-cov-2"
52573,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.087719298,"is, sars-cov-2, by, the, genetic"
52574,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.087719298,"is, sars-cov-2, the, at, genome"
52575,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.087719298,"related, to, sars-cov-2, the, bat"
52576,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.087719298,"the, sars-cov-2, to, a, and"
52577,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.087719298,"the, of, viruses, are, to"
52578,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.087719298,"the, of, viruses, spike, to"
52579,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.087719298,"the, also, to, are, of"
52580,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.087719298,"to, have, the, and, which"
52581,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.087719298,"the, a, which, to, and"
52582,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.087719298,"to, is, the, which, and"
52583,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.087719298,"have, a, to, and, the"
52584,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.087719298,"through, in, and, to, a"
52585,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.087719298,"human, mice, and, in, intestinal"
52586,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.087719298,"the, as, of, bat, is"
52587,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.087719298,"of, the, by, to, virus"
52588,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.087719298,"the, of, genetic, is, as"
52589,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.087719298,"covid-19, to, the, in, known"
52590,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.087719298,"the, are, more, in, and"
52591,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.087719298,"these, to, a, bat, in"
52592,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.087719298,"humans, be, through, and, in"
52593,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.087719298,"a, the, with, market, of, to, by, or, had, exposure"
52594,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.087719298,"the, was, found, to, identical"
52595,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.087719298,"that, of, from, to, an, a, coronavirus, in, with, the"
52596,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.087719298,"the, and, also, a, in, to, ace2, that, bat, of"
52597,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.087719298,"the, that, in, a, genome, as, it, to, events, from"
52598,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.087719298,"the, from, on, and, were, in, with, these, by, of, had, a, as, to, that"
52599,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.087719298,"the, results, of, that, likely, to, a, with, bat, genome"
52600,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.087719298,"in, a, of, the, are, that, this, from, were, market"
52601,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.087719298,"a, at, the, of, and, in, on, animals, that, were"
52602,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.087719298,"from, such, and, this, the, of, that, may, in, a"
52603,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.087719298,"the, on, market., were, collected"
52604,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.087719298,"the, of, covid-19, a, to"
52605,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.087719298,"natural, of, the, a, to"
52606,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.087719298,"the, that, to, and, sars"
52607,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.087719298,"human, and, are, in, many"
52608,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.087719298,"of, the, covid-19, and, with"
52609,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.087719298,"the, covid-19, is, of, in"
52610,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.087719298,"the, and, in, with, all, these, of, that, at, one"
52611,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.087719298,"that, the, of, and, is"
52612,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.087719298,"the, of, that, are, with"
52613,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.087719298,"that, for, virus, infected, with"
52614,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.087719298,"to, with, the, into, virus"
52615,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.087719298,"that, the, is, a, for"
52616,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.087719298,"to, humans, through, contact, with"
52617,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.087719298,"in, including, from, and, sars-cov-2"
52618,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.087719298,"from, in, that, sars-cov-2, to"
52619,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.087719298,"and, the, of, to, natural"
52620,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.087719298,"in, which, to, of, and"
52621,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.087719298,"the, sars-, cov-2, virus, genetic"
52622,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.087719298,"that, the, similarity, of, as"
52623,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.087719298,"the, human, to, a, which"
52624,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.087719298,"the, in, not, that, is"
52625,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.087719298,"is, to, the, that, from"
52626,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.087719298,"in, a, to, that, may"
52627,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.087719298,"the, that, sars-cov-2, natural, selection"
52628,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.087719298,"to, the, key, of, rbd"
52629,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.087719298,"sars-cov-2, the, of, coronaviruses, from"
52630,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.087719298,"a, of, the, however,, with"
52631,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.087719298,"is, in, the, that, not"
52632,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.",0.087719298,"a, the, of, in, with"
52633,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.087719298,"the, that, provides, additional, this"
52634,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.087719298,"indicated, that, a, in, of"
52635,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.087719298,"the, viruses, to, of, spike"
52636,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.087719298,"the, of, a, viruses, in, multiple, to, that, sars, and"
52637,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.087719298,"the, of, and, sars-cov, both"
52638,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.087719298,"evidence, indicates, that, the, and"
52639,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.087719298,"the, of, from, animal, hosts"
52640,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.087719298,"that, the, of, a, high"
52641,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.087719298,"is, a, that, the, for"
52642,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.087719298,"viruses, the, of, that, these"
52643,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.087719298,"of, in, the, been, that"
52644,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.087719298,"the, by, of, in, that"
52645,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.087719298,"the, reservoir, that, in, and"
52646,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.087719298,"all, have, that, of, and"
52647,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.087719298,"the, natural, that, in, and"
52648,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.087719298,"of, the, are, in, viruses"
52649,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.087719298,"the, evidence, indicates, that, and"
52650,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.087719298,"the, of, natural, present, and"
52651,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.087719298,"that, bats, pangolins, the, for"
52652,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.087719298,"of, the, with, that, not"
52653,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.087719298,"in, the, these, have, ("
52654,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.087719298,"the, bats, even, in, of"
52655,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.087719298,"bats, mammals, of, and, other"
52656,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.087719298,"of, in, to, with, and"
52657,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.087719298,"humans, through, contact, with, to"
52658,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.087719298,"in, the, was, humans, and"
52659,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.087719298,"a, the, of, and, in"
52660,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.087719298,"viruses, the, in, and, pangolins"
52661,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.087719298,"protein, similar, of, receptor, in"
52662,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.087719298,"on, the, of, sars-cov-2, is"
52663,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.087719298,"the, virus, in, from, at"
52664,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.087719298,"s, the, of, is, similar"
52665,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.087719298,"in, the, of, a, to, on, as, by, had, with, these, were, and, that, from"
52666,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.087719298,"the, that, of, with, and, these, in, all, one, at"
52667,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.087719298,"the, by, in, were, their"
52668,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.087719298,"of, in, which, were, their"
52669,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.087719298,"the, and, in, bats, from"
52670,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.087719298,"and, between, in, an, the"
52671,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.087719298,"a, of, the, and, that"
52672,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.087719298,"the, to, which, for, infection"
52673,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.087719298,"that, a, of, been, by"
52674,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.087719298,"a, that, the, been, by"
52675,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.087719298,"the, most, of, humans, from"
52676,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.087719298,"of, a, the, by, from"
52677,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.087719298,"the, likely, that, and, mers-cov"
52678,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.087719298,"a, from, the, has, identified"
52679,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.087719298,"a, of, bat, from, identified"
52680,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.087719298,"sars-cov-2, been, a, and, bat"
52681,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.087719298,"genome, sequence, that, bat, and"
52682,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.087719298,"the, from, to, identity, with"
52683,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.087719298,"the, a, from, intermediate, to"
52684,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.087719298,"coronavirus, with, to, sars-cov-2, in"
52685,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.087719298,"sars-cov-2, of, the, virus, analysis"
52686,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.087719298,"on, genomic, of, natural, a"
52687,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.087719298,"the, other, by, that, a"
52688,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.087719298,"the, scientific, that, a, of"
52689,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.087719298,"are, coronavirus, the, in, with"
52690,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.087719298,"of, the, work, is, with"
52691,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.087719298,"that, the, with, or, of"
52692,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.087719298,"the, of, is, that, with"
52693,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.087719298,"such, as, in, they, to"
52694,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.087719298,"even, that, sars-cov-2, they, as"
52695,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.087719298,"that, of, a, sars-cov-2, the"
52696,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.087719298,"this, that, from, in, the, such, a, and, of, may"
52697,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.087719298,"the, was, found, identical, to"
52698,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.087719298,"the, that, sars-cov-2, natural, laboratory"
52699,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.087719298,"the, of, as, genetic, is"
52700,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.087719298,"that, as, sars-cov-2, even, they"
52701,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.087719298,"that, sars-cov-2, the, with, of"
52702,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.087719298,"the, and, a, of, human"
52703,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.087719298,"present, the, natural, of, and"
52704,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.087719298,"in, of, and, have, to"
52705,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.087719298,"more, sequences, bats, of, and"
52706,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.087719298,"in, that, are, more, to"
52707,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.087719298,"of, to, that, sars-cov-2, and"
52708,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.087719298,"that, bats, are, of, and"
52709,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.087719298,"from, is, to, the, that"
52710,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.087719298,"the, that, this, provides, additional"
52711,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.087719298,"in, which, to, of, sars-cov-2"
52712,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.087719298,"the, has, is, that, coronavirus"
52713,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.087719298,"the, is, that, a, has"
52714,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.087719298,"the, sequences, coronaviruses, two, in"
52715,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.087719298,"natural, of, the, to, that"
52716,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.087719298,"that, bats, the, pangolins, for"
52717,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.087719298,"that, sars-cov-2, a, the, from"
52718,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.087719298,"that, in, the, virus, of"
52719,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.087719298,"suggest, that, and, to, the"
52720,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.087719298,"in, the, a, of, sars-cov-2"
52721,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.087719298,"in, the, of, a, sars-cov-2"
52722,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.087719298,"et, al., the, of, in"
52723,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.087719298,"the, of, probable, origin, sars-cov-2"
52724,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.087719298,"a, of, in, was, to"
52725,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.087719298,"was, from, a, sequence, in"
52726,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.087719298,"in, found, from, one, to"
52727,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.087719298,"a, to, in, these, bat"
52728,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.087719298,"of, the, human, in, to"
52729,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.087719298,"the, viral, of, in, and"
52730,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.087719298,"have, and, in, to, of"
52731,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.087719298,"and, been, the, of, hosts"
52732,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.087719298,"to, and, have, a, the"
52733,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.087719298,"suggest, the, of, virus, and"
52734,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.087719298,"a, of, coronavirus, and, the"
52735,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.087719298,"of, the, in, that, by"
52736,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.087719298,"a, natural, of, on, genomic"
52737,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.087719298,"genome, the, to, and, that"
52738,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.087719298,"the, on, that, could, be"
52739,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.087719298,"results, that, the, provide, for"
52740,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.087719298,"viruses, the, in, pangolins, and"
52741,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.087719298,"to, that, the, bats, be"
52742,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.087719298,"that, sars-cov-2, has, been, and"
52743,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.087719298,"that, sars-cov-2, from, and, viruses"
52744,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.087719298,"of, the, has, been, that"
52745,hese close genetic relations suggest that they all have their ecological origin in bat populations,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.087719298,"that, all, origin, in, bat"
52746,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.087719298,"the, bat, in, same, to"
52747,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.087719298,"sars-cov-2, and, larger, that, the"
52748,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.087719298,"sars-cov-2, the, has, that, with"
52749,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.087719298,"the, of, and, bat, sequences"
52750,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.087719298,"of, pangolin, sars-cov-2, sequences, the"
52751,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.087719298,"the, origin, have, and, sars-cov-2"
52752,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.087719298,"have, the, sars-cov-2, and, bat"
52753,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.087719298,"cov, and, sars-cov-2, all, with"
52754,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.087719298,"the, and, that, for, of"
52755,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.087719298,"probable, origin, of, sars-cov-2, the"
52756,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.087719298,"the, of, and, early, in"
52757,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.087719298,"suggest, of, virus, and, the"
52758,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.087719298,"the, of, results, a, to, bat, with, genome, that, likely"
52759,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.087719298,"the, that, of, are, with"
52760,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.087719298,"the, of, is, and, with"
52761,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.087719298,"bats, are, that, of, and"
52762,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.087719298,"cov, and, all, sars-cov-2, with"
52763,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.087719298,"the, sars-cov-2, and, are, in"
52764,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.087719298,"in, that, the, virus, of"
52765,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.087719298,"to, the, of, which, virus"
52766,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.087719298,"to, the, that, bats, be"
52767,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.087719298,"the, a, from, to, with"
52768,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.087719298,"from, the, of, a, to"
52769,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.087719298,"to, the, key, rbd, of"
52770,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.087719298,"for, as, the, in, that"
52771,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.087719298,"sars-cov-2, of, the, and, suggested"
52772,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.087719298,"sars-cov-2, been, animal, a, in"
52773,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.087719298,"sars-cov-2, the, that, would, from"
52774,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.087719298,"a, be, the, that, but"
52775,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.087719298,"identified, a, of, from, bat"
52776,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.087719298,"the, and, also, a, are"
52777,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.087719298,"a, that, sars-cov-2, for, to"
52778,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.087719298,"recently, sars-cov-2, of, to, that"
52779,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.087719298,"a, to, in, that, may"
52780,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.087719298,"are, zoonotic, to, that, and"
52781,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.087719298,"bats, are, to, hosts, of"
52782,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.087719298,"a, in, that, to, of"
52783,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.087719298,"and, to, important, in, of"
52784,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.087719298,"the, of, a, natural, to"
52785,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.087719298,"to, that, natural, the, of"
52786,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.087719298,"the, is, to, be, likely"
52787,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.087719298,"the, are, also, to, of"
52788,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.087719298,"the, also, to, a, that, bat, ace2, and, in, of"
52789,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.087719298,"also, a, are, the, and"
52790,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.087719298,"and, that, similar, of, in"
52791,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.087719298,"of, and, that, is, to"
52792,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.087719298,"of, is, similar, to, bat"
52793,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.087719298,"to, the, may, intermediate, host"
52794,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.087719298,"the, natural, of, sars-cov-2, and"
52795,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.087719298,"the, genetic, sars-, cov-2, virus"
52796,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.087719298,"analysis, of, the, sars-cov-2, virus"
52797,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.087591241,"a, of, the, and, these, were, by, with, found, that, 18, collected"
52798,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.087591241,"collected, by, a, of, the, found, that, were, 18, and, these, with"
52799,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.0875,"a, the, of, and, in, data, that"
52800,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.0875,"in, a, large, of, animal, are, viruses"
52801,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.0875,"of, revealed, that, for, with, or, virus"
52802,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.0875,"of, with, palm, civet, the, to, virus"
52803,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.0875,"the, of, is, in, a, to, 2017,"
52804,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.0875,"the, of, a, in, with, as, to"
52805,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.0875,"the, it, was, of, sars-cov-2, in, a"
52806,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.0875,"the, that, of, has, not, origin, a"
52807,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.0875,"that, the, of, new, a, after, covid-19"
52808,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.0875,"in, and, sars-cov-2, bat, the, between, is"
52809,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.0875,"the, that, virus, from, a, sequence, in"
52810,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.0875,"in, bats, are, to, that, of, and"
52811,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.0875,"sars-cov-2, in, a, of, and, that, the"
52812,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.0875,"of, market, in, that, animal, with, the"
52813,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.0875,"that, is, an, animal, to, a, human"
52814,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.0875,"in, an, was, that, from, to, and"
52815,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.0875,"was, in, a, team, are, to, the"
52816,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.0875,"a, of, in, is, the, for, to"
52817,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.0875,"a, of, and, data, that, the, in"
52818,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.0875,"at, the, and, in, found, is, most"
52819,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.0875,"the, and, to, that, sars-cov-2, is, of"
52820,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.0875,"the, that, january, to, and, with, a"
52821,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.0875,"in, the, of, as, confirmed, to, and"
52822,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.0875,"the, of, as, a, that, virus, is"
52823,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.0875,"the, of, a, was, patients, and, market"
52824,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.0875,"for, from, samples, at, the, market, positive"
52825,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.0875,"et, that, the, sars-cov-2, to, of, and"
52826,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.0875,"that, to, human, an, animal, a, is"
52827,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.0875,"the, market, have, in, to, and, an"
52828,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.0875,"as, the, to, bat, such, close, and"
52829,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.0875,"of, with, a, to, the, in, direct"
52830,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.0875,"origin, of, has, a, that, not, the"
52831,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.0875,"the, sars-cov-2, by, be, with, in, insertion"
52832,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.0875,"the, is, by, in, found, similar, to"
52833,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.0875,"the, and, from, nucleotide, found, in, to"
52834,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.0875,"a, of, the, that, sars-cov-2, and, in"
52835,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.0875,"and, in, that, the, of, hosts, sars-cov-2"
52836,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.0875,"in, with, the, and, to, that, sars-cov-2"
52837,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.0875,"in, the, obtained, and, to, that, are"
52838,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.0875,"and, in, found, to, that, the, are"
52839,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.0875,"bats, of, and, a, to, that, in"
52840,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.0875,"the, of, that, virus, from, a, or"
52841,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.0875,"from, it, the, of, that, sars-cov-2, a"
52842,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.0875,"the, close, to, bat, such, as, and"
52843,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.0875,"the, of, with, other, appears, to, its"
52844,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.0875,"in, a, team, to, the, are, was"
52845,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.0875,"a, of, the, in, 2017,, is, to"
52846,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.0875,"the, in, found, is, similar, to, by"
52847,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.0875,"and, to, the, sars-cov-2, may, in, a"
52848,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.0875,"the, identified, a, of, that, by, and"
52849,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.0875,"of, revealed, that, for, virus, with, or"
52850,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.0875,"to, with, the, of, virus, palm, civet"
52851,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.0875,"the, of, animal, with, market, that, in"
52852,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.0875,"of, that, the, a, animal, or, for"
52853,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.0875,"as, a, of, the, in, to, with"
52854,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.0875,"that, from, a, the, virus, sequence, in"
52855,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.0875,"the, nucleotide, and, in, found, from, to"
52856,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.0875,"that, a, the, of, virus, or, from"
52857,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.0875,"that, was, an, to, from, and, in"
52858,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.0875,"as, the, of, and, in, confirmed, to"
52859,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.0875,"are, viruses, in, a, large, of, animal"
52860,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.0875,"the, samples, from, at, market, positive, for"
52861,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.0875,"a, with, the, in, its, samples, collected"
52862,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.0875,"january, the, a, that, with, and, to"
52863,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.0875,"the, have, an, in, market, to, and"
52864,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.0875,"direct, of, to, a, in, with, the"
52865,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.0875,"the, and, a, in, to, direct, of"
52866,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.0875,"a, of, the, in, was, it, sars-cov-2"
52867,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.0875,"and, a, of, sars-cov-2, in, the, for"
52868,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.0875,"with, samples, the, in, its, collected, a"
52869,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.0875,"of, covid-19, a, that, after, new, the"
52870,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.0875,"a, of, that, animal, for, the, or"
52871,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.0875,"a, the, was, and, market, of, patients"
52872,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.0875,"and, the, of, a, that, this, is"
52873,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.0875,"of, the, and, zoonotic, to, ability, potential"
52874,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.0875,"by, a, of, the, that, identified, and"
52875,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.0875,"from, a, and, has, hosts, to, the"
52876,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.0875,"the, has, a, from, to, hosts, and"
52877,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.0875,"it, that, sars-cov-2, a, the, of, from"
52878,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.0875,"a, to, in, may, sars-cov-2, the, and"
52879,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.0875,"bats, are, of, and, in, that, to"
52880,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.0875,"the, of, appears, to, with, other, its"
52881,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.0875,"the, sars-cov-2, and, of, et, to, that"
52882,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.0875,"the, insertion, in, sars-cov-2, with, be, by"
52883,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.0875,"in, a, of, to, the, is, for"
52884,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.0875,"the, of, is, for, in, a, to"
52885,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.0875,"and, the, for, of, sars-cov-2, in, a"
52886,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.0875,"the, between, sars-cov-2, and, is, in, bat"
52887,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.0875,"in, the, and, are, to, that, obtained"
52888,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.0875,"to, a, of, in, bats, and, that"
52889,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.0875,"sars-cov-2, in, of, and, that, the, hosts"
52890,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.0875,"found, in, the, and, are, to, that"
52891,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.0875,"of, a, to, and, the, in, direct"
52892,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.0875,"of, zoonotic, potential, and, the, ability, to"
52893,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.087378641,"the, that, was, in, is, by, its, sars-cov-2, any"
52894,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.087378641,"that, had, a, the, virus, was, in, also, did"
52895,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.087378641,"to, the, bats, be, in, of, from, humans, found"
52896,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.087378641,"that, a, the, of, he, evidence, is, to, an"
52897,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.087378641,"are, to, in, viruses, is, was, that, and, other"
52898,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.087378641,"is, that, sars-cov-2, was, by, the, its, in, any"
52899,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.087378641,"it, is, that, sars-cov-2, if, the, of, or, at"
52900,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.087378641,"the, animals, that, as, at, collected, were, infected, by"
52901,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.087378641,"that, to, he, the, an, a, of, is, evidence"
52902,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.087378641,"of, the, been, to, who, worked, in, had, that"
52903,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.087378641,"in, a, to, the, from, bats, and, at, virus"
52904,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.087378641,"of, to, the, who, worked, in, that, had, been"
52905,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).",0.087378641,"in, the, first, known, animal, of, that, as, also, was, to, different, species, by, a, coronavirus, is, and"
52906,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.087378641,"the, that, is, of, or, it, if, sars-cov-2, at"
52907,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.087378641,"in, a, of, the, different, this, bat, and, viruses"
52908,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.087378641,"bat, to, a, as, in, multiple, the, of, species"
52909,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.087378641,"also, that, was, a, had, the, virus, did, in"
52910,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.087378641,"the, animals, that, infected, were, at, as, by, collected"
52911,"The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.087378641,"the, of, is, in, a, different, coronavirus, species, animal, known, to, and, was, that, first, also, as, by"
52912,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.087378641,"also, found, evidence, that, the, of, may, to, as"
52913,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.087378641,"the, to, humans, from, bats, in, of, be, found"
52914,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.087378641,"the, virus, in, bats, and, to, from, at, a"
52915,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.087378641,"this, of, and, viruses, different, bat, a, in, the"
52916,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.087378641,"the, of, multiple, bat, species, in, as, a, to"
52917,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.087378641,"the, of, and, in, all, one, collected, at, also"
52918,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.087378641,"the, a, of, that, from, civets, infected, such, and"
52919,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.087378641,"are, that, other, was, to, and, is, viruses, in"
52920,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.087378641,"a, of, the, are, by, that, other, to, virus"
52921,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.087378641,"the, that, are, with, of, “the, is, as, for"
52922,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.087378641,"the, to, this, market,, that, in, with, involved, of"
52923,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.087378641,"at, in, the, collected, all, one, of, and, also"
52924,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.087378641,"with, the, market,, of, to, that, in, involved, this"
52925,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.087378641,"that, civets, infected, from, the, such, a, and, of"
52926,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.087378641,"the, are, to, a, of, that, virus, by, other"
52927,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.087378641,"the, are, for, of, as, “the, with, is, that"
52928,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.087378641,"the, are, to, for, of, as, that, bats, and"
52929,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.087378641,"may, the, of, found, that, as, also, to, evidence"
52930,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.087301587,"the, of, to, as, with, found, could, be, and, recombination, thus"
52931,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.087301587,"a, of, the, and, in, to, it, with, for, that, not"
52932,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.087301587,"in, the, of, for, it, not, to, that, with, and, a"
52933,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.087301587,"as, the, recombination, found, to, be, with, of, thus, could, and"
52934,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.087301587,"in, with, the, by, and, to, that, of, guangdong, as, 16"
52935,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.087301587,"the, guangdong, and, in, with, by, 16, of, as, to, that"
52936,"The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.087248322,"of, furin, cleavage, sites, in, have, been, coronaviruses, hcov-oc43, other, such, as, naturally"
52937,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).",0.087248322,"naturally, furin, cleavage, sites, have, been, in, other, of, coronaviruses, such, as, hcov-oc43"
52938,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.086956522,"a, of, viruses, bats"
52939,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.086956522,"in, a, large, of"
52940,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.086956522,"of, a, or, that, in, and, new, the"
52941,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.086956522,"the, and, a, of, in, naturally"
52942,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.086956522,"and, a, the, bats, of, or"
52943,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.086956522,"that, bats, and, pangolins"
52944,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.086956522,"genetic, and, sars-cov, bat"
52945,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.086956522,"in, to, sars-cov-2, and"
52946,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.086956522,"in, very, to, sars-cov-2"
52947,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.086956522,"many, other, coronaviruses, and"
52948,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.086956522,"this, the, and, of"
52949,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.086956522,"a, large, of, in"
52950,"All human coronaviruses have animal origins, namely, natu- 

ral hosts","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.086956522,"coronaviruses, animal"
52951,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.086956522,"are, a, coronaviruses, in"
52952,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.086956522,"a, of, in, viruses"
52953,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.086956522,"coronaviruses, the, three, and"
52954,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.086956522,"of, the, southeast, asia, and, coronaviruses"
52955,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.086956522,"scientists, have, the, of"
52956,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.086956522,"virus, for, and, were"
52957,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.086956522,"coronavirus, bats, of, and, that, animals"
52958,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.086956522,"that, one, or, of"
52959,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.086956522,"similar, to"
52960,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.086956522,"and, in, similar, to"
52961,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.086956522,"sars-cov-2, and, of, to"
52962,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.086956522,"of, species, and, by"
52963,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.086956522,"of, from, and, more"
52964,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.086956522,"genome, to, such, more"
52965,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.086956522,"in-, and"
52966,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.086956522,"for, and"
52967,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.086956522,"in, also, the, of"
52968,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.086956522,"also, the, of, in"
52969,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.086956522,"are, in"
52970,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.086956522,"of, the, also, are"
52971,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.086956522,"and, from, bat, to, which, may"
52972,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.086956522,"to, the, have, of, and, emergence"
52973,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.086956522,"a, to, the, of, with, as"
52974,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.086956522,"with, to, sars-cov-2, in"
52975,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.086956522,"the, as, a, of, to, infected"
52976,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.086956522,"from, to, the, it"
52977,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.086956522,"the, of, coronaviruses, that, sequences, to"
52978,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.086956522,"of, have, the, to, from, including"
52979,"Bats have been reported as being the rich source of 

coronaviruses","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.086956522,"have, been"
52980,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.086956522,"a, of, and, that, the, new, or, in"
52981,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.086956522,"that, sars-cov-2, a, the, virus, did, exist, in"
52982,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.086956522,"that, sars-cov-2, a, the, covid-19, of, virus, or"
52983,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.086956522,"to, the, for, and, not, a, in, of, that, have, an, or"
52984,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.086956522,"a, of, and, the, in, naturally"
52985,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.086956522,"is, sars-cov-2, a, the, genetic, in"
52986,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.086956522,"to, the, be, and, a, in, of, coronaviruses, have, found"
52987,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.086956522,"sars-cov-2, a, virus, that, did, exist, in, the"
52988,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.086956522,"the, sars-cov-2, a, genetic, is, in"
52989,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.086956522,"the, other, of, and, a, laboratory"
52990,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.086956522,"virus, and, that, sars-cov-2"
52991,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.086956522,"with, a, and, sars-cov-2"
52992,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.086956522,"sars-cov-2, their, is, and"
52993,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.086956522,"of, the, that, and, are, viruses"
52994,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.086956522,"of, many, coronaviruses, and"
52995,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.086956522,"and, to, that, the, of, are"
52996,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.086956522,"the, have, as, host"
52997,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.086956522,"that, the, to, with"
52998,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.086956522,"that, the, identified, sars-cov-2"
52999,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.086956522,"the, that, was, to, is, of, it, sars-cov-2"
53000,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.086956522,"found, to, sars-cov, that"
53001,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.086956522,"are, of, the, and"
53002,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.086956522,"sars-cov-2, and, virus, that"
53003,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.086956522,"sars-cov-2, and, bat, ratg13"
53004,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.086956522,"of, analysis, that, similar"
53005,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.086956522,"in, that, similar, of"
53006,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.086956522,"of, in, receptor, protein, and, that"
53007,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.086956522,"patients, of, between, and"
53008,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.086956522,"sars-cov-2, including, and, of"
53009,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.086956522,"the, of, to, in, and, sars-cov"
53010,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.086956522,"to, of"
53011,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",Originating from reservoir of bat,0.086956522,"reservoir, bat"
53012,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.086956522,"origin, including, the, and"
53013,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.086956522,"in, a, of, the, that, as"
53014,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.086956522,"of, the, human, in"
53015,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.086956522,"the, that, its, of, in, a"
53016,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.086956522,"have, as, the, host"
53017,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.086956522,"the, than, and, reservoirs"
53018,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.086956522,"the, of, most, after"
53019,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.086956522,"the, of, with, a, and, recombination"
53020,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.086956522,"of, the, in, their, is, and"
53021,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.086956522,"be, a, in, the, that, for"
53022,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.086956522,"and, the, that, was, in, a"
53023,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.086956522,"the, of, (manis, javanica)"
53024,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.086956522,"of, the, as, intermediate"
53025,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.086956522,"of, pangolins, the, intermediate"
53026,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.086956522,"phylogenetic, from, the, of"
53027,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.086956522,"the, to, of, from"
53028,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.086956522,"as, the, to, close, them, humans"
53029,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.086956522,"the, of, spillover, to"
53030,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.086956522,"to, the, plausible, of"
53031,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.086956522,"on, the, that, to"
53032,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.086956522,"in, the, of, to, on, were, that, likely, this, it"
53033,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.086956522,"that, to, it, in"
53034,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.086956522,"transmission, to, and, the"
53035,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.086956522,"the, to, a, and, adapted, of, coronavirus, an"
53036,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.086956522,"the, sars-cov-2, to, be, of, and"
53037,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.086956522,"of, the, by, that, and, are"
53038,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.086956522,"the, of, that, t"
53039,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.086956522,"the, by, and, that, of, are"
53040,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.086956522,"the, that, bats, are"
53041,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.086956522,"and, that, the, of, bats, are"
53042,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","All human coronaviruses have animal origins, namely, natu- 

ral hosts",0.086956522,"hosts, human"
53043,hese close genetic relations suggest that they all have their ecological origin in bat populations,"All human coronaviruses have animal origins, namely, natu- 

ral hosts",0.086956522,"all, have"
53044,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.086956522,"sars-, the, of, may"
53045,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.086956522,"the, be"
53046,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.086956522,"to, and, the, transmission"
53047,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.086956522,"that, the, virus, as"
53048,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.086956522,"the, sars-cov-2, of, sequence"
53049,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.086956522,"the, of, sequence, sars-cov-2"
53050,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.086956522,"at, to, the, from"
53051,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.086956522,"in, from, to, the"
53052,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.086956522,"at, the, level, which"
53053,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,zoonotic origins of SARS-CoV-2 by natural evolution,0.086956522,"sars-cov-2, natural"
53054,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",zoonotic origins of SARS-CoV-2 by natural evolution,0.086956522,"of, by"
53055,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.086956522,"the, a, zoonotic, to"
53056,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.086956522,"the, to, a, high"
53057,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.086956522,"the, sars-cov-2, to, with, high, origin"
53058,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.086956522,"the, origin, sars-cov-2, with"
53059,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.086956522,"the, and, to, which"
53060,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.086956522,"the, of, which, to"
53061,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.086956522,"to, sars-cov-2,, the, which"
53062,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.086956522,"of, and, which, to"
53063,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.086956522,"the, and, geographic, in"
53064,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.086956522,"in, animals, the, was"
53065,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.086956522,"shows, of, in, the"
53066,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.086956522,"of, genome, and, to"
53067,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.086956522,"of, that, the, bats"
53068,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.086956522,"the, of, for, that"
53069,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.086956522,"the, sars, bats, viral, reservoirs, for, of, that"
53070,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.086956522,"of, the, viral, for"
53071,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.086956522,"the, coronavirus, from, with"
53072,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.086956522,"the, are, and, humans"
53073,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.086956522,"of, the, animal, infections"
53074,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","with the first case being linked to  

a seafood market",0.086956522,"a, to, the, with"
53075,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","with the first case being linked to  

a seafood market",0.086956522,"with, to"
53076,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.086956522,"sars-cov-2, has, through, the"
53077,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.086956522,"bats, of, the, found"
53078,"Coronaviruses are naturally hosted and developmentally 

formed by bats.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.086956522,"and, by"
53079,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.086956522,"that, the, origin, a"
53080,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.086956522,"that, and, sars-cov-2, to, on, with"
53081,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.086956522,"has, been, and, to, that, through"
53082,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.086956522,"bat, as, sars-cov-2, and, genetic, similarity"
53083,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.086956522,"in, are, found, and"
53084,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.086956522,"studies, similarity, sars-cov-2, and, as, a"
53085,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.086956522,"the, sars-cov-2, has, through"
53086,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.086956522,"phylogenetic, the, of, from"
53087,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.086956522,"of, the, from, that, and, at"
53088,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.086956522,"from, of, and, the"
53089,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.086956522,"ratg13, at, the, of"
53090,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.086956522,"and, from, that, the, of, coronavirus"
53091,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.086956522,"from, zoonotic"
53092,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.086956522,"sars-cov-2, other"
53093,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.086956522,"and, sars-cov-2, closely, related"
53094,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.086956522,"sars-cov-2, from, bats, and"
53095,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.086956522,"of, from, and, sars-cov-2"
53096,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.086956522,"at, the, to, from"
53097,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.086956522,"the, viruses, and, are, of, that"
53098,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.086956522,"that, and, are, the, of, by"
53099,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.086956522,"and, that, from, the, at, of"
53100,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.086956522,"the, which, that, of, and, from"
53101,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.086956522,"sars-cov-2, a, that, from, and, the"
53102,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.086956522,"at, a, from, in, the, by, were, zoonotic, of, and"
53103,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.086956522,"the, and, of, a, zoonotic, origin"
53104,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.086956522,"this, that, the, of, origin, and"
53105,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.086956522,"the, of, that, sars-cov-2, are, a"
53106,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.086956522,"from, the, probable, of"
53107,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.086956522,"the, of, to, and, animals, market"
53108,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.086956522,"the, sars-cov-2, that, are"
53109,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.086956522,"be, the, that, sars-cov-2"
53110,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.086956522,"animal, in, the, with"
53111,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.086956522,"the, earliest, cases, that"
53112,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.086956522,"two, the, lineage, in"
53113,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.086956522,"to, that, the, we"
53114,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.086956522,"study, that, the, to"
53115,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.086956522,"of, the, market, virus"
53116,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.086956522,"a, of, market, by, the, virus"
53117,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.086956522,"the, of, at, virus"
53118,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.086956522,"the, animal, in, and"
53119,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.086956522,"the, animal, of, been"
53120,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.086956522,"the, of, most, coronavirus"
53121,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.086956522,"the, were, in, to"
53122,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.086956522,"to, the, than, in"
53123,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.086956522,"in, animal, the, to, closely, related"
53124,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.086956522,"the, reservoirs, and, than"
53125,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.086956522,"of, were, to, and"
53126,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.086956522,"of, in, from, at"
53127,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.086956522,"from, with, a, sars-cov-2"
53128,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.086956522,"that, the, in, a"
53129,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.086956522,"in, the, sars-cov-2, that"
53130,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.086956522,"were, of, and, to"
53131,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.086956522,"the, of, and, were"
53132,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.086956522,"from, an, animal, a"
53133,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.086956522,"sars-cov-2, from, a, in"
53134,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.086956522,"may, the, of, sars-"
53135,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.086956522,"although, the, from, sars-cov-2"
53136,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.086956522,"the, has, an, is, to, that, of, coronavirus"
53137,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.086956522,"the, is, one, of, evidence, a, natural, to"
53138,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.086956522,"this, to, that, natural, the, of, evidence, is"
53139,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.086956522,"the, natural, is, it, what, an, to, of"
53140,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.086956522,"that, and, sars-cov-2, to, other, in"
53141,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.086956522,"the, virus, had, of, and, to"
53142,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.086956522,"the, genetic, of, other, to, be"
53143,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.086956522,"was, that, the, of, sars-cov-2, is, to, it"
53144,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.086956522,"is, that, the, of, viruses, to, sars-cov-2, or"
53145,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.086956522,"that, the, earliest, cases"
53146,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.086956522,"that, sars-cov-2, by, the"
53147,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.086956522,"occur, the, that, a"
53148,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.086956522,"a, in, the, as"
53149,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.086956522,"genetic, that, a, the"
53150,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.086956522,"the, from, market, positive, for, that"
53151,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.086956522,"that, the, covid-19, virus, to, of"
53152,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.086956522,"are, a, of, virus, the, found"
53153,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.086956522,"is, that, the, of, to, covid-19"
53154,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.086956522,"that, from, a, to, first, in"
53155,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.086956522,"on, the, virus, a, that, and"
53156,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.086956522,"on, in, the, and, that, of, environmental, were"
53157,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.086956522,"data, that, not, a, it, in"
53158,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.086956522,"the, that, at, of, virus, and"
53159,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.086956522,"evidence, that, to, an"
53160,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.086956522,"the, that, of, market, all, at"
53161,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.086956522,"a, the, and, on, virus, that"
53162,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.086956522,"the, on, a, virus, to, that"
53163,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.086956522,"the, and, that, is"
53164,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.086956522,"and, this, virus, the"
53165,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.086956522,"the, were, from, and"
53166,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.086956522,"the, also, from, and"
53167,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.086956522,"of, to, that, they"
53168,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.086956522,"to, and, have, a"
53169,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.086956522,"and, have, from, in"
53170,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.086956522,"from, and, that, have, in, infect"
53171,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.086956522,"from, that, all, and"
53172,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.086956522,"and, of, in, the"
53173,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.086956522,"of, be, the, possible"
53174,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.086956522,"to, the, be, possible"
53175,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.086956522,"a, the, pandemic, of"
53176,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.086956522,"in, a, with, the"
53177,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.086956522,"a, in, with, the"
53178,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.086956522,"that, to, with, the"
53179,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.086956522,"that, were, in, the, market, a, and, of"
53180,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.086956522,"a, and, with, to, in, the"
53181,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.086956522,"in, and, grouped, with, that, the"
53182,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.086956522,"a, of, in, close"
53183,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.086956522,"of, virus, the, market"
53184,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.086956522,"that, they, of, to"
53185,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.086956522,"of, the, those, in"
53186,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.086956522,"the, that, to, which"
53187,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.086956522,"the, of, clustering, with"
53188,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.086956522,"also, in, of, and, the, as"
53189,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.086956522,"they, in, the, their"
53190,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.086956522,"of, the, from, that, and, which"
53191,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.086956522,"that, to, the, an, coronavirus, of, is, has"
53192,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.086956522,"has, the, of, which"
53193,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.086956522,"sars-cov-2, and, from, bats"
53194,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.086956522,"a, the, from, that, sars-cov-2, and"
53195,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.086956522,"and, that, is, bats"
53196,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.086956522,"that, was, and, a"
53197,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.086956522,"be, to, the, that"
53198,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.086956522,"to, the, has, shown"
53199,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.086956522,"sars-cov-2, the, have, been, to, pangolin, with, coronavirus"
53200,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.086956522,"from, although, the, sars-cov-2"
53201,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.086956522,"the, bat, identity, with"
53202,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.086956522,"the, coronavirus, isolated, from"
53203,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.086956522,"the, that, sars-cov-2, by"
53204,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.086956522,"the, of, a, to, and, virus"
53205,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.086956522,"of, to"
53206,"All human coronaviruses have animal origins, namely, natu- 

ral hosts","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.086956522,"human, hosts"
53207,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.086956522,"to, the, bat, and"
53208,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.086956522,"an, animal, was, the"
53209,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.086956522,"bats, are, the, and"
53210,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.086956522,"a, market, in, the, to, virus"
53211,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.086956522,"bats, and, to, the"
53212,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.086956522,"a, genetic, the, in"
53213,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.086956522,"the, in, and, that, through, a"
53214,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.086956522,"through, that, the, covid-19"
53215,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.086956522,"of, that, the, either, exposure, to"
53216,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.086956522,"the, has, shown, to"
53217,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.086956522,"has, the, of, are"
53218,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.086956522,"is, and, to, which, in, bats"
53219,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.086956522,"that, in"
53220,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.086956522,"has, to"
53221,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.086956522,"to, in"
53222,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.086956522,"as, that, virus, the"
53223,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.086956522,"the, a, as, of"
53224,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.086956522,"that, the, of, was, evidence, a"
53225,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.086956522,"a, the, of, virus"
53226,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.086956522,"the, was, a, virus, that, as, of, at"
53227,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.086956522,"in, that, the, who, to, virus"
53228,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.086956522,"and, that, the, in"
53229,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.086956522,"to, in, the, and"
53230,"bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.086956522,"the, sars-like"
53231,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.086956522,"bat, cov"
53232,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.086956522,"sars-, to, intermediate, host, is, the"
53233,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.086956522,"sars-like, the"
53234,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.086956522,"they, the"
53235,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.086956522,"the, have, been, from"
53236,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.086956522,"it, was, that, the"
53237,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.086956522,"a, the, of, with, or, as"
53238,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.086956522,"that, the, of, have, in, china"
53239,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.086956522,"the, as, a, of, that, infected"
53240,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.086956522,"the, that, from, market, for, positive"
53241,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.086956522,"suggesting, that, hosts, for"
53242,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.086956522,"for, the, civets, that, from, palm"
53243,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.086956522,"the, market, palm, civets, at, samples, for, that, from, positive"
53244,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.086956522,"the, results, from, that"
53245,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.086956522,"of, a, viruses, bats"
53246,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.086956522,"the, possible, be, of"
53247,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.086956522,"the, of, that, viruses, a, could"
53248,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.086956522,"not, only, a, of, but, the"
53249,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.086956522,"coronavirus, to, human, been"
53250,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.086956522,"group, of"
53251,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.086956522,"the, which, to, and"
53252,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.086956522,"that, and, the, for"
53253,"In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.086956522,"to, more, than, human"
53254,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.086956522,"the, of, bat, to, similar, for, can, is"
53255,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.086956522,"of, the, for, used"
53256,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.086956522,"similar, to, of, the"
53257,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.086956522,"the, of, was, to, as, and"
53258,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.086956522,"bat, to"
53259,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.086956522,"and, to, human, in"
53260,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.086956522,"to, in, and, hosts"
53261,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.086956522,"sars-cov-2, as, genetic, similarity, and, bat"
53262,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.086956522,"that, the, of, bat, as, genetic"
53263,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Coronaviruses are naturally hosted and developmentally 

formed by bats.",0.086956522,"by, are"
53264,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.086956522,"are, of, the, has"
53265,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.086956522,"the, of, human, that"
53266,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.086956522,"sars-cov-2, spike"
53267,"zoonotic corona- 

viruses have become an increasing threat to human health,","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.086956522,"have, to"
53268,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.086956522,"the, of, in, a"
53269,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.086956522,"viruses, a, the, same"
53270,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.086956522,"pangolin, the, viruses, in"
53271,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.086956522,"in, the, of, pangolin"
53272,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.086956522,"sars-cov, and, bat, genetic"
53273,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.086956522,"and, of, bat, that"
53274,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.086956522,"is, that, of, and"
53275,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.086956522,"is, that, bats, and"
53276,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.086956522,"is, have, likely, bat"
53277,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.086956522,"of, that, likely, bat"
53278,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.086956522,"from, that, a, to"
53279,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.086956522,"a, that, to, virus"
53280,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.086956522,"that, is"
53281,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.086956522,"the, to, it, from"
53282,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.086956522,"to, the, is, for"
53283,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.086956522,"is, a, the, from"
53284,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.086956522,"to, coronaviruses, the, from, bats, bat, closely, related"
53285,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.086956522,"isolated, from, sars-cov-2, the"
53286,"this one jumped from bats origin  

into humans","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.086956522,"from, bats"
53287,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.086956522,"to, of, in, the"
53288,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.086956522,"is, from, to, in"
53289,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.086956522,"to, the, in, bats"
53290,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.086956522,"are, and, found, in"
53291,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.086956522,"the, or, in, and"
53292,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.086956522,"the, could, an, or"
53293,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.086956522,"has, a, sars-cov-2, and"
53294,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.086956522,"and, origin, all, sars-cov-2"
53295,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.086956522,"a, sars-cov-2, origin, that"
53296,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.086956522,"in, has"
53297,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.086956522,"sars-cov-2, the, that, from"
53298,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.086956522,"the, animal, from, that, species, infected, is, and"
53299,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.086956522,"to, sars-cov-2, of, and, it, that"
53300,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.086956522,"through, that, of, to"
53301,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.086956522,"to, that, of, sars-cov-2"
53302,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.086956522,"the, of, and, to, virus, had"
53303,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.086956522,"of, to, coronavirus, that"
53304,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.086956522,"the, sequence, of, with"
53305,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.086956522,"the, of, was, virus"
53306,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.086956522,"with, the, and, of, bat, closest"
53307,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.086956522,"the, and, this, virus"
53308,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.086956522,"the, in, and, lung"
53309,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.086956522,"the, by, isolated, in"
53310,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.086956522,"the, by, of, in, and, this"
53311,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.086956522,"the, with, isolated, from"
53312,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.086956522,"to, the, from, be"
53313,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.086956522,"of, to, be, with"
53314,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.086956522,"and, the, in, lung"
53315,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.086956522,"in, the, and, as"
53316,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.086956522,"the, coronaviruses, and, three"
53317,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.086956522,"and, viruses, are, the"
53318,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.086956522,"to, and, that, viruses"
53319,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.086956522,"are, of, and, which, in, human"
53320,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.086956522,"a, of, and, the, or, bats"
53321,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.086956522,"as, a, of, the, to, with"
53322,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.086956522,"the, with, or, as, a, of"
53323,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.086956522,"a, with, sars-, and, to, the"
53324,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.086956522,"a, coronaviruses, to, with, the, and"
53325,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.086956522,"and, a, of, the, to, human"
53326,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.086956522,"the, pangolin, as, intermediate"
53327,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.086956522,"analysis, that, similar, of"
53328,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.086956522,"such, more, to, genome"
53329,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.086956522,"as, the, was, to, of, and"
53330,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.086956522,"that, of, related, coronavirus"
53331,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.086956522,"of, to, the, virus, that, covid-19"
53332,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.086956522,"bat, to, approximately, the"
53333,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.086956522,"the, of, virus, to, sars, that"
53334,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.086956522,"of, with, sequences, in"
53335,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.086956522,"from, and, the, sars-cov-2"
53336,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.086956522,"the, from, by, a"
53337,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.086956522,"ace2, receptor, animal, or"
53338,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.086956522,"bat, is, at, the"
53339,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.086956522,"and, of, wild, the"
53340,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.086956522,"of, the, which, wild"
53341,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.086956522,"the, of, and, via"
53342,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.086956522,"the, of, which, animal, and, wild"
53343,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.086956522,"is, the, are, hosts"
53344,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.086956522,"a, that, and, was"
53345,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.086956522,"and, seafood, market, a"
53346,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.086956522,"at, that, a, in"
53347,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.086956522,"to, sars-cov, that, are"
53348,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.086956522,"in, a, that, from"
53349,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.086956522,"in, from, a, sars-cov-2"
53350,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.086956522,"in, a, from, that"
53351,"expended to make the simple point 

that COVID-19 had a natural origin.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.086956522,"that, a"
53352,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.086956522,"is, in"
53353,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.086956522,"sars-cov-2, bat"
53354,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.086956522,"most, that, a, likely, the, of"
53355,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.086956522,"the, from, on, most, were, in, these, of, a, that"
53356,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.086956522,"analysis, the, for, from"
53357,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.086956522,"the, that, with, of"
53358,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.086956522,"the, with, sars-cov-2, that"
53359,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.086956522,"that, with, the, of"
53360,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.086956522,"the, of, that, to, coronaviruses, sequences"
53361,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.086956522,"the, are, humans, and"
53362,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.086956522,"other, sars-cov-2"
53363,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.086956522,"humans, the, of, sars-cov-2"
53364,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.086956522,"are, other, sars-cov-2, and"
53365,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.086956522,"of, the, are, other"
53366,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.086956522,"the, are, of, sars-cov-2"
53367,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.086956522,"are, to, of, the"
53368,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.086956522,"wild, the, of, which"
53369,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.086956522,"of, which, results, the"
53370,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","Bats are natural hosts of many of the known  

coronaviruses",0.086956522,"the, known"
53371,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.086956522,"to, and, which, may, from, bat"
53372,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.086956522,"in, to, is, which, bats, and"
53373,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.086956522,"between, sars-cov-2, and, to, in, high, that, bat, coronavirus, may"
53374,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.086956522,"to, can, be, and, in, bats"
53375,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.086956522,"sars-cov-2, a, as, studies, similarity, and"
53376,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.086956522,"the, that, of, and, sequences, at"
53377,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.086956522,"of, the, hypothesis, that"
53378,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.086956522,"study, that, of, to, intermediate, the"
53379,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.086956522,"pangolin, to, the, is"
53380,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.086956522,"sars-cov-2, a, with, the"
53381,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.086956522,"to, of, the, a"
53382,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.086956522,"that, similar, of, in"
53383,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.086956522,"in, a, of, to, the, coronavirus, at, genome"
53384,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.086956522,"the, that, of, these"
53385,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.086956522,"of, the, a, that"
53386,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.086956522,"human, are"
53387,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.086956522,"the, of, are, sars-cov-2"
53388,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.086956522,"the, of, that, hypothesis"
53389,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.086956522,"and, of, sars-cov-2, to"
53390,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.086956522,"that, the, of, at"
53391,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.086956522,"spike, sars-cov-2"
53392,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.086956522,"natural, of, the, in"
53393,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.086956522,"sars-cov-2, the, of, from"
53394,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.086956522,"of, the, its, similar"
53395,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","this one jumped from bats origin  

into humans",0.086956522,"origin, from"
53396,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.086956522,"the, a, to, coronavirus"
53397,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.086956522,"by, a, to, the"
53398,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.086956522,"origin,, in"
53399,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.086956522,"of, the, have, which"
53400,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.086956522,"the, bats, of, found"
53401,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.086956522,"a, of, the, are, virus, found"
53402,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.086956522,"the, of, by, found, a, virus"
53403,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K",0.086956522,"more, than, to, human"
53404,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.086956522,"a, of, the, bat"
53405,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.086956522,"a, the, bat, in"
53406,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.086956522,"found, that, to, sars-cov"
53407,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.086956522,"for, suggesting, that, hosts"
53408,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.086956522,"are, to, that, sars-cov"
53409,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.086956522,"to, that, are, related"
53410,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.086956522,"to, suggesting, that, bats"
53411,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.086956522,"the, of, to, in, and, wild"
53412,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.086956522,"in, the, sars-cov-2, for"
53413,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.086956522,"a, has, or, to"
53414,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.086956522,"genetic, the, in, a"
53415,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.086956522,"coronavirus, the, pangolin, been, to, have, with, sars-cov-2"
53416,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.086956522,"sars-cov-2, between, and, bat, high, to, that, may, coronavirus, in"
53417,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.086956522,"to, the, coronavirus, have, been, in, of, and, that, animals"
53418,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.086956522,"bat, to, as, the"
53419,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.086956522,"the, of, location, a, to, yunnan"
53420,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.086956522,"the, of, a, human, as, to"
53421,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.086956522,"the, be, location, spillover, of, a"
53422,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.086956522,"as, to, the, of, may, a"
53423,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.086956522,"the, to, a, bat"
53424,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.086956522,"the, viruses, that, to, is, of, or, sars-cov-2"
53425,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.086956522,"of, to, the, that, covid-19, is"
53426,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.086956522,"to, the, sars-, is, intermediate, host"
53427,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.086956522,"the, study, of, that, intermediate, to"
53428,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.086956522,"2, to, the, in, that, bats"
53429,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.086956522,"of, the, were, and"
53430,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.086956522,"of, in, the, rhinolophus"
53431,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.086956522,"in, with, the, and, sars-cov-2, of"
53432,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.086956522,"the, sars-cov-2, and, which"
53433,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.086956522,"in, found, of, genome"
53434,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.086956522,"that, sars-cov-2"
53435,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.086956522,"the, nucleotide, from, to"
53436,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.086956522,"been, the, of, animal"
53437,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.086956522,"a, of, that, animal, by, the"
53438,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.086956522,"ratg13,, is, the, that"
53439,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.086956522,"the, of, to, high"
53440,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.086956522,"to, the, ratg13, has"
53441,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.086956522,"from, the, and, also"
53442,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.086956522,"and, the, also, to, as, cluster, moreover,, in"
53443,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.086956522,"from, an, as, the"
53444,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.086956522,"and, from, the, of"
53445,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.086956522,"the, from, and, with"
53446,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.086956522,"the, ratg13, at, of"
53447,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.086956522,"the, has, which, of"
53448,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.086956522,"of, the, sequence, with"
53449,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.086956522,"has, sequence, with, sars-cov-2"
53450,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.086956522,"of, with, at, rbd"
53451,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.086956522,"of, than, that, with"
53452,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.086956522,"to, that, this, be"
53453,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.086956522,"to, be, coronavirus, that"
53454,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.086956522,"in, similar, to, and"
53455,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.086956522,"the, from, to, nucleotide"
53456,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.086956522,"the, most, from, to, by, and"
53457,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.086956522,"for, the, a, in, human, to"
53458,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.086956522,"in, the, sars-cov-2, rbd"
53459,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.086956522,"of, that, the, is, these, as"
53460,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.086956522,"as, also, the, of, and, in"
53461,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.086956522,"a, of, the, also, that, or"
53462,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.086956522,"that, sars-cov-2, with, on, and, to"
53463,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.086956522,"that, other, sars-cov-2, to, and, in"
53464,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.086956522,"in, the, that, are, to, and"
53465,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.086956522,"that, through, has, been, and, to"
53466,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.086956522,"the, that, these, are, use, it"
53467,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.086956522,"sars-cov-2, a, to, the"
53468,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.086956522,"of, species, by, and"
53469,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.086956522,"as, a, the, to"
53470,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.086956522,"a, team, to, the"
53471,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.086956522,"a, an, the, to"
53472,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.086956522,"in, the, of, human"
53473,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.086956522,"known, to, of, with"
53474,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.086956522,"the, with, of, to"
53475,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.086956522,"at, of, from, in"
53476,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.086956522,"in, to, with, sars-cov-2"
53477,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.086956522,"in, to, sars-cov-2, with"
53478,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.086956522,"similarity, sars-cov-2, in, to"
53479,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.086956522,"the, sars-cov-2, that, for"
53480,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.086956522,"the, of, coronaviruses, asia, and, southeast"
53481,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.086956522,"and, it, that, of, sars-cov-2, to"
53482,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.086956522,"sars-cov-2, of, covid-19, a, virus, or, that, the"
53483,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.086956522,"a, the, of, pandemic"
53484,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.086956522,"of, covid-19, in, the"
53485,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.086956522,"the, of, a, natural"
53486,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.086956522,"in, the, to, sars-cov-2, is, of"
53487,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.086956522,"the, in, or, and"
53488,"The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.","Bats are the second  

largest order of mammals, with over 1,230 species.",0.086956522,"the, species."
53489,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.086956522,"close, to, the, them, as, humans"
53490,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.086956522,"many, other, such, as, humans, and"
53491,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.086956522,"the, to, which, many, bat, and"
53492,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.086956522,"the, of, as, viruses"
53493,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.086956522,"the, of, as, intermediate, to, and"
53494,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.086956522,"the, that, to, in"
53495,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.086956522,"the, closely, related, in, to, that"
53496,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.086956522,"and, to, the, that, sars-cov-2, in"
53497,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.086956522,"and, for, virus, were"
53498,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.086956522,"to, other, and, in"
53499,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.086956522,"in, similar, of, the"
53500,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.086956522,"bat, that, the, of, as, genetic"
53501,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.086956522,"the, that, in, of, to, a, but, covid-19"
53502,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.086956522,"the, of, is, similar, to, bat, for, can"
53503,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.086956522,"moreover,, in, to, the, cluster, also, and, as"
53504,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.086956522,"sars-cov-2, to, from, of"
53505,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.086956522,"of, known, to, with"
53506,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.086956522,"from, to, of, sars-cov-2, have, a"
53507,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.086956522,"the, approximately, to, bat"
53508,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.086956522,"the, bat, is, at"
53509,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.086956522,"the, to, sars-cov-2,, sars-cov-2"
53510,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.086956522,"and, a, sars-, to, the, with"
53511,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.086956522,"the, team, a, to"
53512,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.086956522,"which, the, by, are, to, and, in, other"
53513,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.086956522,"on, the, virus, a, that, to"
53514,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.086956522,"that, the, virus, to, sars, of"
53515,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.086956522,"a, of, virus, by, the, found"
53516,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.086956522,"to, the, of, yunnan, location, a"
53517,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.086956522,"the, to, that, closely, related, in"
53518,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.086956522,"wiv, a, virus, that, the, in"
53519,"This suggests that the BANAL series may be able to directly infect  

humans.",all three BANAL series viruses also use ACE2 as an entry receptor.,0.086956522,"banal, series"
53520,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.086956522,"the, scientists, have, of"
53521,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.086956522,"that, of, to, through"
53522,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.086956522,"to, through, human, experiments"
53523,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","This suggests that the BANAL series may be able to directly infect  

humans.",0.086956522,"to, the, this, that"
53524,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","This suggests that the BANAL series may be able to directly infect  

humans.",0.086956522,"to, that, the, may"
53525,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.086956522,"2, sars-cov-, the, in"
53526,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.086956522,"have, their, the, of"
53527,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.086956522,"have, a, to, and"
53528,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.086956522,"the, same, viruses, a"
53529,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.086956522,"at, which, the, sars-cov-2,"
53530,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.086956522,"furin, cleavage, site, and"
53531,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.086956522,"through, experiments, to, human"
53532,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.086956522,"bat, of, by, the"
53533,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.086956522,"was, and"
53534,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.086956522,"in, and"
53535,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.086956522,"in, the, known, virus, to, is, closely, related"
53536,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.086956522,"its, the, of, similar"
53537,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.086956522,"coronaviruses, are, in, a"
53538,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.086956522,"coronaviruses, and, a, to, the, with"
53539,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.086956522,"the, these, are, to, and, in, other, may"
53540,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.086956522,"identified, that, sars-cov-2, the"
53541,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.086956522,"the, covid-19, through, that"
53542,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.086956522,"the, that, covid-19, identified, and, case"
53543,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.086956522,"the, that, covid-19, and"
53544,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.086956522,"in, and, sars-cov-2, that, the, is"
53545,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.086956522,"that, the, with, were"
53546,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.086956522,"that, the, covid-19, case, identified, and"
53547,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.086956522,"wuhan, the, of, between, these, and"
53548,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.086956522,"on, the, by, of, and, a"
53549,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.086956522,"that, did, not, a, to, evolved, in, an"
53550,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.086956522,"of, a, virus, the, market, by"
53551,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.086956522,"in, closely, related, to, the, animal"
53552,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.086956522,"the, virus, to, a, market, in"
53553,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.086956522,"the, of, exposure, to, that, either"
53554,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.086956522,"the, that, animal, of, by, a"
53555,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.086956522,"is, that, the, species, and, infected, from, animal"
53556,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.086956522,"is, the, closely, related, virus, to, known, in"
53557,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.086956522,"a, virus, from, to, only, of, and, as, wildlife, markets"
53558,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.086956522,"the, from, civets, for, that, palm"
53559,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.086956522,"to, a, in, the, human, for"
53560,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.086956522,"the, sequence, of, to, and, in"
53561,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.086956522,"the, to, for, a, from, likely"
53562,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.086956522,"the, of, to, that, from, humans."
53563,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.086956522,"the, samples, from, civets, at, market, positive, for, that, palm"
53564,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.086956522,"that, not, from, a, to, it, in, an, intermediate, host"
53565,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.086956522,"the, to, as, of, intermediate, and"
53566,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.086956522,"a, of, at, the, outbreak, in"
53567,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.086956522,"that, the, of, and, more, from"
53568,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.086956522,"to, the, of, from, a, virus"
53569,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.086956522,"of, for, to, a, have, or, that, not, in, an, and, the"
53570,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.086956522,"the, and, have, to, be, a, of, found, in, coronaviruses"
53571,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.086956522,"viral, of, the, sars, that, bats, reservoirs, for"
53572,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.086956522,"present, that, bats, the, reservoir, of, and, have, in, for"
53573,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.086956522,"the, as, a, species, of, that, from, to, humans, and"
53574,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.086956522,"bats, of, and, a, large, to, that, in, as, east"
53575,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.086956522,"from, to, closely, related, coronaviruses, bat, bats, the"
53576,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.086956522,"a, coronavirus, in, the, genome, to, of, at"
53577,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.086956522,"the, other, of, in, and, this, novel, coronavirus, than, a"
53578,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.086956522,"to, a, of, an, coronavirus, and, adapted, the"
53579,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.086956522,"on, the, of, that, were, to, in, it, this, likely"
53580,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.086956522,"a, of, the, from, by, and, at, zoonotic, in, were"
53581,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.086956522,"of, a, the, virus, to, bat, and, sars"
53582,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.086956522,"that, the, of, were, in, a, and, market"
53583,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.086956522,"that, the, of, covid-19, in, but, a, to"
53584,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.086956522,"for, between, and, that, in, the, of, sars-cov-2"
53585,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.086956522,"the, shows, in, of"
53586,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.086956522,"to, the, of, spillover"
53587,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.086956522,"a, to, the, of"
53588,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.086956522,"a, origin, of, the, and, zoonotic"
53589,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.086956522,"to, one, the, a, of, is, evidence, natural"
53590,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.086956522,"and, a, seafood, market"
53591,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.086956522,"a, the, to, and"
53592,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.086956522,"a, of, the, known"
53593,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.086956522,"and, to, the, of, is, natural"
53594,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.086956522,"a, in, the, known"
53595,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.086956522,"in, the, and, to, that, are"
53596,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.086956522,"that, the, and, sars"
53597,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.086956522,"and, in, to, that, the, are"
53598,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.086956522,"the, known, to, in"
53599,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.086956522,"the, of, at, market, all, that"
53600,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.086956522,"that, the, sequences, of, and, at"
53601,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.086956522,"all, that, are, in"
53602,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.086956522,"in, the, of, that, its, a"
53603,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.086956522,"the, of, be, location, a, spillover"
53604,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.086956522,"that, sars-cov-2, from, a, it, in"
53605,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.086956522,"the, of, that, sars-cov-2, was, from"
53606,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.086956522,"the, of, and, environmental, in, on, that, were"
53607,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.086956522,"the, from, that, all, to, and"
53608,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.086956522,"that, the, most, a"
53609,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.086956522,"into, sars-cov-2, with, that, the, is"
53610,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","expended to make the simple point 

that COVID-19 had a natural origin.",0.086956522,"that, a, the, to"
53611,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","expended to make the simple point 

that COVID-19 had a natural origin.",0.086956522,"a, that"
53612,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.086956522,"bats, to, sars-cov-2, and"
53613,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.086956522,"results, of, the, which"
53614,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.086956522,"the, in, wiv, a, virus, that"
53615,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.086956522,"its, the, that, sars-cov-2, in, a"
53616,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.086956522,"the, most, evidence, that"
53617,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.086956522,"another, sars-cov-2, a, the"
53618,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.086956522,"of, coronavirus, that, related"
53619,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.086956522,"is, coronavirus, a, that"
53620,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.086956522,"the, of, used, for"
53621,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.086956522,"is, not, the, from"
53622,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.086956522,"the, likely, of, bats"
53623,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.086956522,"the, that, to, bat"
53624,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.086956522,"the, that, ratg13,, is"
53625,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.086956522,"not, that, the, a"
53626,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.086956522,"suggests, that, in, the"
53627,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.086956522,"the, that, occur, a"
53628,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.086956522,"a, that, and, the"
53629,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.086956522,"the, that, can, which"
53630,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.086956522,"the, is, it, of"
53631,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.086956522,"sars-cov-2, to, in, very"
53632,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.086956522,"the, an, to, of"
53633,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.086956522,"more, from, of, and"
53634,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.086956522,"sars-cov-2, with, and, a"
53635,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.086956522,"a, the, recombination, of, and, with"
53636,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.086956522,"and, the, of, via"
53637,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.086956522,"of, sars-cov-2, the, these"
53638,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.086956522,"the, recombination, and, of"
53639,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.086956522,"however,, we, of, based"
53640,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.086956522,"been, to, human, coronavirus"
53641,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.086956522,"have, and, to, from, animals, through"
53642,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.086956522,"the, most, after, of"
53643,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.086956522,"coronavirus, most, the, of"
53644,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.086956522,"a, that, the, most"
53645,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.086956522,"genome, the, bat, of"
53646,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.086956522,"the, of, that, new"
53647,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.086956522,"a, of, the, viruses, that, could"
53648,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.086956522,"the, of, and, sequence, in, to"
53649,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.086956522,"sars-cov, and, to, the, of, in"
53650,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.086956522,"of, to, sequence, in"
53651,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.086956522,"to, the, which, that"
53652,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.086956522,"to, and, the, which"
53653,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.086956522,"the, to, that, which"
53654,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",The COVID-19 most likely developed from bat origin coronaviruses,0.086956522,"most, the"
53655,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.086956522,"the, animal, of, infections"
53656,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.086956522,"these, as, the, of, that, is"
53657,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.086956522,"the, of, that, these, a, covid-19"
53658,"t some virus detected in pangolins 

were capable of infecting humans.","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.086956522,"of, humans."
53659,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.086956522,"that, are, in, all"
53660,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.086956522,"in, an, viruses, to"
53661,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.086956522,"be, the"
53662,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.086956522,"be, to, the, in"
53663,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.086956522,"have, the, of, which"
53664,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.086956522,"the, that, been, by"
53665,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.086956522,"reported, that, the, by, in, of"
53666,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.086956522,"and, most, the, of"
53667,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.086956522,"of, animals, and, that, bats, coronavirus"
53668,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.086956522,"to, have, the, emergence, of, and"
53669,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.086956522,"and, of, the, have, been, to, animals, in, that, coronavirus"
53670,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.086956522,"of, that, the, covid-19, a, these"
53671,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.086956522,"that, the, in, china, have, of"
53672,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.086956522,"in, the, of, for, that, and"
53673,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.086956522,"the, bats, for, and, reservoir, in, of, that, present, have"
53674,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.086956522,"can, the, which, that"
53675,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.086956522,"that, the, virus, which"
53676,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.086956522,"in, with, the, results, that, they"
53677,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.086956522,"that, the, which, same"
53678,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.086956522,"in, were, found, be, that, the"
53679,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.086956522,"the, in, a, as"
53680,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.086956522,"the, of, rhinolophus, in"
53681,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.086956522,"the, known, of, a"
53682,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.086956522,"a, known, in, the"
53683,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.086956522,"one, of, that, or"
53684,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.086956522,"that, of, one, the"
53685,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.086956522,"by, the, isolated, in"
53686,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.086956522,"and, can, be, to, in, bats"
53687,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.086956522,"and, other, to, in"
53688,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.086956522,"in, with, bats,, other"
53689,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.086956522,"to, the, and, from"
53690,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.086956522,"the, to, from, and"
53691,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.086956522,"the, in, humans, and"
53692,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.086956522,"markets, of, from, as, only, virus, to, wildlife, a, and"
53693,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.086956522,"in, by, other, and, which, are, to, the"
53694,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.086956522,"are, other, to, in, may, these, the, and"
53695,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.086956522,"the, sars-cov, and, to, in, of"
53696,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.086956522,"the, market, animals, to, and, of"
53697,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.086956522,"a, of, to, the, and, virus"
53698,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.086956522,"wild, animal, and, the, of, which"
53699,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.086956522,"to, the, in, wild, and, of"
53700,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.086956522,"in, the, and, a, palm, civet"
53701,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.086956522,"have, the, a, of, sars-cov, and"
53702,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.086956522,"sars-cov-2, their, and, is"
53703,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.086956522,"the, of, is, and, in, their"
53704,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.086956522,"in, the, two, lineage"
53705,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.086956522,"have, the, of, and"
53706,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.086956522,"from, the, virus, is"
53707,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.086956522,"sars-cov-2, from, of, in, the, with"
53708,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.086956522,"on, in, the, of, a, from, that, these, were, most"
53709,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.086956522,"the, their, in, they"
53710,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.086956522,"in, origin,"
53711,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.086956522,"have, in, and, from"
53712,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.086956522,"animals, that, and, the"
53713,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.086956522,"for, the, from, a, likely, to"
53714,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.086956522,"to, a, which, from"
53715,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.086956522,"the, of, have, to, from, including"
53716,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.086956522,"a, of, the, not, but, only"
53717,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.086956522,"and, from, animals, to, through, have"
53718,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.086956522,"as, a, of, the, to, infected"
53719,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.086956522,"that, the, infected, as, a, of"
53720,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.086956522,"the, and, from, most, to, by"
53721,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.086956522,"to, the, as, and, a, of, species, from, that, humans"
53722,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.086956522,"a, bat, that, sars-cov-2"
53723,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.086956522,"and, human, that, a"
53724,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.086956522,"a, that, bat, and"
53725,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.086956522,"with, and, that, sars-cov-2, bat, cov"
53726,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.086956522,"sars-cov-2, and, pangolin, to, the, in"
53727,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.086956522,"and, the, in, bats"
53728,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.086956522,"in, the, is, and"
53729,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.086956522,"and, in, is, the"
53730,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.086956522,"and, coronaviruses, many, other"
53731,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.086956522,"and, of, coronaviruses, many"
53732,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.086956522,"an, is, of, and"
53733,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.086956522,"as, many, such, and, other, humans"
53734,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.086956522,"is, and, an, of"
53735,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.086956522,"the, of, are, other"
53736,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.086956522,"has, a, to, or"
53737,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.086956522,"also, a, of, that, the, or"
53738,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.086956522,"the, or, origin, of"
53739,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.086956522,"the, animal, with, in"
53740,"Coronaviruses are naturally hosted and developmentally 

formed by bats.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.086956522,"are, by"
53741,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.086956522,"other, with, bats,, in"
53742,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.086956522,"by, with, are, the"
53743,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.086956522,"that, to, in, it"
53744,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.086956522,"sars-cov-2, to, from, in"
53745,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.086956522,"in, a, to, that, first, from"
53746,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.086956522,"a, in, data, it, that, not"
53747,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.086956522,"that, a, an, evolved, in, did, not, to"
53748,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.086956522,"a, in, an, to, it, that, from, intermediate, host, not"
53749,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.086956522,"it, that, sars-cov-2, in, from, a"
53750,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.086956522,"that, in, to, humans"
53751,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.086956522,"a, the, that, not"
53752,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.086956522,"that, have, in, infect, and, from"
53753,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.086956522,"a, that, the, sars-cov-2, in, its"
53754,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.086956522,"the, of, to, sars-cov, and, in"
53755,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.086956522,"the, an, animal, was"
53756,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.086956522,"the, as, for, from"
53757,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.086956522,"the, from, as, an"
53758,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.086956522,"be, sars-cov-2, to, the"
53759,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.086956522,"genetic, the, that, a"
53760,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.086956522,"that, and, human, a"
53761,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",Genetic evidence suggesting otherwise is yet to be presented.,0.086956522,"evidence, be"
53762,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",Genetic evidence suggesting otherwise is yet to be presented.,0.086956522,"suggesting, be"
53763,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.086956522,"it, the, are, use, that, these"
53764,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.086956522,"the, origin, of, and"
53765,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.086956522,"of, the, have, their"
53766,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.086956522,"sars-cov-2, has, the, origin"
53767,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.086956522,"natural, of, and, to, in, such"
53768,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.086956522,"a, from, the, is"
53769,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.086956522,"the, in, is, from"
53770,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.086956522,"the, is, not, from"
53771,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.086956522,"a, by, from, in, the, is"
53772,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.086956522,"of, which, to, that, and, horseshoe"
53773,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.086956522,"that, of, to, and, are, sars-cov-2"
53774,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.086956522,"bat, sars-cov-2, with, ratg13"
53775,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.086956522,"the, most, that, evidence"
53776,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.086956522,"from, to, be, the"
53777,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.086956522,"has, the, ratg13, to"
53778,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.086956522,"the, been, that, by"
53779,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.086956522,"the, appears, to, be"
53780,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.086956522,"be, the, and, an"
53781,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.086956522,"the, of, to, other, be, genetic"
53782,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.086956522,"sars-cov-2, the, coronaviruses, of"
53783,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.086956522,"to, the, appears, be"
53784,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.086956522,"bat, ratg13, and, sars-cov-2"
53785,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.086956522,"bat, ratg13, sars-cov-2, we"
53786,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.086956522,"the, of, sars-cov-2, these"
53787,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.086956522,"is, that, a, coronavirus"
53788,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.086956522,"sars-cov-2, to, be, of, and, the"
53789,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.086956522,"to, the, high, with, sars-cov-2, origin"
53790,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.086956522,"to, the, of, plausible"
53791,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.086956522,"origin, of, the, this, that, and"
53792,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.086956522,"that, to, this, the, of, is, evidence, natural"
53793,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.086956522,"that, the, be, sars-cov-2"
53794,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.086956522,"all, that, and, from"
53795,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.086956522,"the, from, results, that"
53796,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.086956522,"to, the, a, bat"
53797,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.086956522,"the, and, that, to, all, from"
53798,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.086956522,"and, that, bats, pangolins"
53799,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.086956522,"for, that, sars-cov-2, and"
53800,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.086956522,"that, the, virus, bats"
53801,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.086956522,"covid-19, the, that, for"
53802,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.086956522,"is, a, the, in, by, from"
53803,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.086956522,"to, the, genome, in, that, bats"
53804,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.086956522,"the, to, many, bat, and, which"
53805,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.086956522,"bat, to, a, the, virus, sars, of, and"
53806,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.086956522,"the, that, virus, which"
53807,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.086956522,"bat, that, and, a"
53808,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.086956522,"of, the, sub-genus, bat, and, sars"
53809,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.086956522,"to, the, bat, which"
53810,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.086956522,"the, of, by, bat"
53811,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.086956522,"in, the, of, a, outbreak, at"
53812,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.086956522,"(2020), the, of, sars-cov-2"
53813,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.086956522,"similarity, of, to, bat"
53814,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.086956522,"sequence, of, to, in"
53815,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.086956522,"shows, of, similarity, to"
53816,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.086956522,"of, to, was, from"
53817,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.086956522,"viral, of, the, for"
53818,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.086956522,"and, a, to, the, of, human"
53819,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.086956522,"the, a, an, to"
53820,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.086956522,"similarity, to, sars-cov-2, in"
53821,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.086956522,"in, viruses, to, an"
53822,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.086956522,"genome, of, and, to"
53823,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.086956522,"found, in, genome, of"
53824,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.086956522,"sequences, and, pangolin, of"
53825,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.086956522,"in, pangolin, and, of"
53826,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.086956522,"that, sars-cov-2, are, with"
53827,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.086956522,"that, sars-cov-2, in, for"
53828,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.086956522,"the, of, pangolins, intermediate"
53829,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.086956522,"by, the, are, with"
53830,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.086956522,"laboratory, and, of, the, other, a"
53831,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.086956522,"protein, and, that, of, receptor, in"
53832,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.086956522,"through, that, the, in, and, a"
53833,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.086956522,"the, by, a, and, of, on"
53834,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.086956522,"in, a, of, the, coronavirus, this, novel, and, than, other"
53835,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.086956522,"sars-cov-2, in, the, with"
53836,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.086956522,"and, of, viruses, with"
53837,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.086956522,"sars-cov-2, of, that, the"
53838,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.086956522,"sars-cov-2, that"
53839,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.086956522,"the, in, to, bats"
53840,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.086956522,"that, bats, to, in, the, 2"
53841,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.086956522,"sars-cov-, 2, in, the"
53842,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.086956522,"genome, in, that, the, to, bats"
53843,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.086956522,"this, that, the, bat"
53844,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.086956522,"that, the, from, and"
53845,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.086956522,"the, of, that, from, and, more"
53846,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.086956522,"(2020), of, sars-cov-2, the"
53847,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.086956522,"the, in, viruses, pangolin"
53848,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.086956522,"pangolin, and, sars-cov-2, to, in, the"
53849,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.086956522,"that, the, grouped, in, with, and"
53850,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.086956522,"sars-cov-2, is, that, into, with, the"
53851,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.086956522,"have, is, likely, bat"
53852,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.086956522,"the, to, which, bat"
53853,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.086956522,"the, in, likely, sars-cov-2"
53854,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.086956522,"of, the, and, closest, with, bat"
53855,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.086956522,"the, results, that, in, with, they"
53856,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.086956522,"pangolin, the, this, of"
53857,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.086956522,"of, the, or, origin"
53858,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.086956522,"the, and, which, sars-cov-2"
53859,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.086956522,"and, the, that, sars"
53860,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.086956522,"the, that, same, which"
53861,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.086956522,"we, sars-cov-2, the, that"
53862,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.086956522,"the, sars-cov-2, origin, has"
53863,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.086956522,"sars-cov-2, with, origin, that"
53864,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.086956522,"of, pangolin, sequences, and"
53865,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.086956522,"all, sars-cov-2, origin, and"
53866,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.086956522,"sars-cov-2, in, this, that"
53867,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.086956522,"the, probable, of, from"
53868,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.086956522,"of, the, wuhan, between, and, these"
53869,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.086956522,"a, of, the, that, sars-cov-2, are"
53870,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.086956522,"clustering, of, the, with"
53871,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.086956522,"that, likely, of, bat"
53872,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.086956522,"with, and, that, sars-cov-2"
53873,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.086956522,"by, with, the, of"
53874,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.086956522,"the, by, of, with"
53875,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.086956522,"the, from, and, for"
53876,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.086956522,"analysis, the, from, for"
53877,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.086956522,"the, of, that, evidence"
53878,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.086956522,"the, and, for, of, that, in, between, sars-cov-2"
53879,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.086956522,"the, a, in, and, palm, civet"
53880,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.086956522,"the, in, from, and"
53881,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.086956522,"the, have, that, of"
53882,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.086956522,"the, of, have, a, and, sars-cov"
53883,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.086956522,"of, the, have, and"
53884,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.086956522,"a, the, that, for"
53885,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.086956522,"sars-cov-2, with, sars-cov, and"
53886,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.086956522,"the, and, is, for"
53887,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.086956522,"that, the, and, for"
53888,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.086956522,"in, the, suggests, that"
53889,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.086956522,"in, of, pangolin, and"
53890,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.086956522,"at, the, of, and, virus, that"
53891,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.086956522,"and, at, the, that, of, sars-cov-2"
53892,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.086956522,"of, shows, similarity, to"
53893,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.086956522,"the, of, and, recombination"
53894,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.086956522,"this, bat, the, that"
53895,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.086956522,"be, in, the, that"
53896,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.086956522,"bats, to, suggesting, that"
53897,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.086956522,"to, sars-cov-2,, sars-cov-2, the"
53898,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.086956522,"the, of, that, from, to, humans."
53899,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.086956522,"the, that, was, of, sars-cov-2, from"
53900,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.086956522,"at, which, in, the"
53901,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.086956522,"we, that, the, to"
53902,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.086956522,"at, of, rbd, with"
53903,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.086956522,"of, and, with, viruses"
53904,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.086956522,"the, by, from, a"
53905,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.086956522,"the, of, a, virus, from, to"
53906,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.086956522,"the, animal, that, in"
53907,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.086956522,"the, for, that, bat"
53908,"Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.086956522,"the, they"
53909,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.086956522,"the, an, and, be"
53910,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.086956522,"bat, and, the, sars-cov-2"
53911,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.086956522,"the, sars-cov-2, a, another"
53912,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.086956522,"that, in, at, a"
53913,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.086956522,"in, the, that, sars-cov-2, is, of"
53914,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.086956522,"a, for, the, be, in, that"
53915,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.086956522,"the, covid-19, that, a"
53916,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.086956522,"the, that, for, covid-19"
53917,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.086956522,"in, be, that, the"
53918,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.086956522,"it, to, the, an, of, is, what, natural"
53919,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.086956522,"it, is, of, the"
53920,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.086956522,"the, of, an, to"
53921,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.086956522,"with, the, and, to, is, of"
53922,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.086956522,"of, in, close, a"
53923,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.086956522,"the, origin, and, including"
53924,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.086956522,"that, of, coronavirus, to"
53925,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.086956522,"with, to, be, of"
53926,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.086956522,"be, that, coronavirus, to"
53927,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.086956522,"that, sars-cov-2, origin, with"
53928,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.086956522,"of, a, to, zoonotic, that, in"
53929,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.086956522,"of, are, human, and, which, in"
53930,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.086956522,"of, a, large, in, to, that, bats, as, and, east"
53931,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.086956522,"such, and, in, to, of, natural"
53932,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.086956522,"in, a, of, to, that, zoonotic"
53933,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.086956522,"sars-cov-2,, at, the, which"
53934,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.086956522,"in, the, at, which"
53935,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.086956522,"the, of, similar, to"
53936,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.086956522,"that, of, sars-cov-2, to"
53937,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.086956522,"of, similar, in, the"
53938,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.086956522,"the, that, be, found, in, were"
53939,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.086956522,"the, of, bat, to"
53940,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.086956522,"viruses, to, that, and"
53941,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.086956522,"of, sars-cov-2, including, and"
53942,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.086956522,"that, evidence, an, to"
53943,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.086956522,"of, also, to, the"
53944,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.086956522,"of, to, the, than"
53945,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.086956522,"the, of, be, to, and, sars-cov-2"
53946,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.086956522,"bat, ratg13, the, sars-cov-2"
53947,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.086956522,"that, a, the, sars-cov-2"
53948,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.086614173,"in, the, of, a, to, bat, found, coronaviruses, be, and, recombination"
53949,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.086614173,"the, of, a, to, as, with, novel, coronaviruses, could, be, and"
53950,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.086614173,"the, that, of, with, market, and, these, in, one, collected, at"
53951,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.086614173,"the, and, to, be, a, of, found, in, bat, coronaviruses, recombination"
53952,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.086614173,"coronaviruses, and, a, novel, to, the, could, be, of, with, as"
53953,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.086614173,"of, the, market, at, and, these, in, with, one, that, collected"
53954,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.086538462,"the, and, of, to, that, between, sars-cov-2, animal, be"
53955,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.086538462,"and, from, at, the, in, early, of, a, virus."
53956,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.086538462,"to, a, from, in, multiple, the, one, of, also"
53957,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.086538462,"to, an, for, the, of, evidence, at, look, that"
53958,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.086538462,"the, is, that, of, known, are, and, in, at"
53959,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.086538462,"that, to, at, the, an, of, look, evidence, for"
53960,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.086538462,"to, the, were, and, a, in, of, high, that"
53961,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.086538462,"to, the, they, in, of, had, that, those, or"
53962,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.086538462,"the, pangolins, from, and, their, with, of, to, infected"
53963,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.086538462,"the, a, in, to, that, bats, and, virus, china"
53964,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.086538462,"from, the, to, a, virus, that, and, in, at"
53965,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.086538462,"the, and, for, a, to, that, is, sars-cov-2, by"
53966,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.086538462,"the, for, to, similar, bat, used, human, of, coronavirus"
53967,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.086538462,"by, of, species, bats,, to, that, intermediate, and, it"
53968,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.086538462,"from, the, for, a, with, as, and, of, its"
53969,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.086538462,"found, that, with, the, of, pangolin, may, have, to"
53970,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.086538462,"the, a, similar, this, bat, and, by, in, of"
53971,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.086538462,"sampled, from, a, is, to, in, the, that, may"
53972,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.086538462,"the, that, a, virus, found, in, animal, evidence, coronavirus"
53973,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.086538462,"in, found, two, related, of, sampled, and, similar, to"
53974,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.086538462,"that, the, of, were, in, to, a, high, and"
53975,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.086538462,"of, to, the, those, in, that, they, had, or"
53976,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.086538462,"that, the, virus, in, bats, and, to, a, china"
53977,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.086538462,"and, bats,, it, that, of, to, intermediate, species, by"
53978,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.086538462,"to, and, of, bats,, it, that, similar, viruses, in"
53979,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.086538462,"that, the, virus, in, and, to, from, at, a"
53980,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.086538462,"the, of, coronavirus, similar, to, human, bat, used, for"
53981,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.086538462,"with, the, of, as, a, for, its, from, and"
53982,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.086538462,"this, of, and, similar, by, bat, a, in, the"
53983,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.086538462,"from, in, also, one, the, of, multiple, a, to"
53984,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.086538462,"a, of, the, from, virus., early, and, at, in"
53985,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.086538462,"in, with, the, by, and, to, that, is, of"
53986,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.086538462,"the, of, be, to, that, between, and, animal, sars-cov-2"
53987,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.086538462,"a, that, the, sars-cov-2, and, for, to, is, by"
53988,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.086538462,"the, that, known, are, in, is, of, and, at"
53989,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.086538462,"in, may, the, from, that, sampled, to, a, is"
53990,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.086538462,"in, the, animal, found, that, virus, a, coronavirus, evidence"
53991,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.086538462,"infected, pangolins, to, from, and, their, with, the, of"
53992,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.086538462,"in, of, found, sampled, two, similar, to, related, and"
53993,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.086538462,"the, is, that, in, of, to, by, and, with"
53994,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.086538462,"of, viruses, in, bats,, to, that, and, similar, it"
53995,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.086538462,"of, the, have, to, pangolin, with, found, that, may"
53996,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.086419753,"the, are, in, of, southern, emergence, bats"
53997,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.086419753,"a, of, in, with, the, being, to"
53998,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.086419753,"that, sars-cov-2, has, have, and, such, the"
53999,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.086419753,"that, human, have, origin, in, which, and"
54000,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.086419753,"that, the, of, to, sars-cov-2, or, covid-19"
54001,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.086419753,"to, a, in, the, human, ace2, for"
54002,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.086419753,"the, to, after, covid-19, for, which, a"
54003,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.086419753,"a, in, that, by, had, the, virus"
54004,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.086419753,"the, of, and, are, to, other, laboratory"
54005,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.086419753,"of, has, human, a, that, in, the"
54006,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.086419753,"a, of, also, and, the, ability, to"
54007,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.086419753,"likely, reservoir, in, found, a, to, genetic"
54008,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.086419753,"sars-cov-2, has, such, have, that, and, the"
54009,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.086419753,"the, of, animal, in, and, market, at"
54010,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.086419753,"as, a, of, the, at, animal, by, an, to, it, evidence, for, one, that"
54011,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.086419753,"laboratory, and, are, to, of, the, other"
54012,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.086419753,"genetic, the, virus, in, and, to, at"
54013,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.086419753,"the, of, more, to, used, for, be"
54014,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.086419753,"the, of, that, from, was, to, as"
54015,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.086419753,"the, of, have, that, was, to, by"
54016,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.086419753,"the, by, was, a, market, to, of"
54017,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.086419753,"has, to, a, virus, that, and, the"
54018,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.086419753,"and, the, also, that, this, virus, is"
54019,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.086419753,"origin, which, human, have, that, in, and"
54020,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.086419753,"that, the, of, was, to, have, by"
54021,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.086419753,"in, the, and, at, to, genetic, virus"
54022,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.086419753,"and, the, huanan, seafood, in, of, was"
54023,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.086419753,"the, of, to, used, for, be, more"
54024,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.086419753,"and, found, to, be, the, of, bats"
54025,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.086419753,"the, bat, to, are, closely, related, bats"
54026,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.086419753,"the, by, with, in, this, of, and"
54027,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.086419753,"of, to, the, that, was, from, as"
54028,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.086419753,"in, and, sars-cov-2, bat, that, between, is"
54029,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.086419753,"sars-cov-2, of, covid-19, to, or, that, the"
54030,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.086419753,"et, al., the, sars-cov-2, to, in, and"
54031,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.086419753,"and, an, from, to, the, in, of"
54032,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.086419753,"the, in, of, were, to, and, an"
54033,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.086419753,"for, to, human, ace2, a, in, the"
54034,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.086419753,"and, the, of, bat, to, sars-related, in"
54035,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.086419753,"that, the, and, also, this, virus, is"
54036,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.086419753,"to, are, closely, related, bat, bats, the"
54037,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.086419753,"bat, and, to, in, the, of, sars-related"
54038,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.086419753,"reservoir, to, a, likely, genetic, found, in"
54039,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.086419753,"a, in, with, the, to, closely, related"
54040,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.086419753,"the, of, market, was, to, a, by"
54041,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.086419753,"the, sequenced, to, by, with, of, and"
54042,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.086419753,"a, of, the, in, being, to, with"
54043,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.086419753,"that, a, by, had, the, virus, in"
54044,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.086419753,"a, closely, related, to, in, with, the"
54045,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.086419753,"that, it, to, one, as, at, the, an, animal, by, a, of, evidence, for"
54046,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.086419753,"the, bats, are, in, emergence, of, southern"
54047,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.086419753,"huanan, seafood, in, the, was, and, of"
54048,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.086419753,"in, an, from, of, to, and, the"
54049,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.086419753,"in, an, of, were, to, and, the"
54050,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.086419753,"bats, the, of, to, and, in, sars-cov"
54051,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.086419753,"in, these, viruses, 2, and, that, the"
54052,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.086419753,"the, of, to, sars-cov, and, in, bats"
54053,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.086419753,"the, of, animal, and, market, at, in"
54054,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.086419753,"the, virus, a, of, which, to, and"
54055,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.086419753,"have, a, of, virus, to, and, the"
54056,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.086419753,"covid-19, which, for, to, a, after, the"
54057,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.086419753,"also, a, the, of, and, ability, to"
54058,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.086419753,"of, the, in, a, to, that, such"
54059,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.086419753,"of, the, are, or, themselves, with, as"
54060,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.086419753,"and, by, this, with, the, in, of"
54061,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.086419753,"et, al., in, to, the, sars-cov-2, and"
54062,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.086419753,"the, sequenced, by, and, to, of, with"
54063,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.086419753,"the, of, have, a, to, and, virus"
54064,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.086419753,"the, that, in, of, and, with, a"
54065,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.086419753,"the, themselves, are, with, of, or, as"
54066,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.086419753,"sars-cov-2, is, between, and, bat, that, in"
54067,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.086419753,"viruses, the, 2, in, and, that, these"
54068,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.086419753,"of, natural, and, zoonotic, to, in, many"
54069,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.086419753,"such, to, the, of, that, in, a"
54070,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.086419753,"bats, the, found, to, be, of, and"
54071,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.086419753,"natural, of, many, and, to, zoonotic, in"
54072,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.086330935,"this, that, had, a, the, an, animal, humans, human, of, at, to"
54073,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.086330935,"that, to, human, this, at, the, had, an, animal, humans, a, of"
54074,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.086330935,"in, the, of, a, to, by, had, with, testing, that, sars, province"
54075,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.086330935,"a, of, in, province, that, sars, with, testing, by, had, the, to"
54076,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.086206897,"in, the, of, that, new"
54077,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.086206897,"a, sars-cov, bat, and, human"
54078,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.086206897,"pangolin, coronaviruses, to, sars-cov-2, in"
54079,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.086206897,"the, of, and, into, humans"
54080,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.086206897,"the, virus, of, from, and"
54081,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.086206897,"the, of, human, natural, this"
54082,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.086206897,"2, of, virus, and, the"
54083,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.086206897,"recent, have, the, of, and"
54084,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.086206897,"to, of, bats, the, and"
54085,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.086206897,"animals, that, infected, with, were"
54086,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.086206897,"revealed, that, of, animals, for"
54087,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.086206897,"of, with, and, more, or"
54088,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.086206897,"one, study, that, with, of"
54089,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.086206897,"of, from, bats, sequences, species"
54090,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.086206897,"from, bats, of, and, more"
54091,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.086206897,"of, and, from, species, 41"
54092,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.086206897,"by, from, of, were, bats"
54093,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.086206897,"sars-, cov-2, to, sequences, the"
54094,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.086206897,"the, of, to, may, and"
54095,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.086206897,"the, of, from, with, and"
54096,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.086206897,"the, to, have, with, of"
54097,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.086206897,"sars-cov-2, a, be, that, coronavirus"
54098,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.086206897,"from, to, the, that, it"
54099,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.086206897,"the, a, bat, and, to"
54100,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.086206897,"a, of, the, found, coronaviruses"
54101,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.086206897,"the, to, which, a, is"
54102,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.086206897,"the, in, that, had, virus"
54103,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.086206897,"globally,, the, of, that, to"
54104,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.086206897,"the, that, these, are, of"
54105,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.086206897,"sars-cov-2, bat, as, to, that"
54106,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.086206897,"sars-cov, a, to, the, of"
54107,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.086206897,"the, sars-cov-2, to, human, that"
54108,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.086206897,"analysis, of, in, and, showed"
54109,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.086206897,"observed, and, in, that, of"
54110,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.086206897,"covs, of, and, the, to"
54111,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.086206897,"of, be, the, that, reservoirs"
54112,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.086206897,"to, the, and, that, be"
54113,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.086206897,"the, a, of, in, human"
54114,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.086206897,"that, bats, the, of, in"
54115,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.086206897,"other, coronaviruses,, and, are, the"
54116,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.086206897,"and, a, to, the, human"
54117,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.086206897,"of, the, sars-cov-2,, were, case"
54118,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.086206897,"of, a, to, and, the"
54119,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.086206897,"the, to, for, sars-cov, can"
54120,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.086206897,"to, the, from, and, as"
54121,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.086206897,"was, to, from, is, in"
54122,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.086206897,"and, other, to, in, the"
54123,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.086206897,"the, of, is, in, that"
54124,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.086206897,"the, and, was, with, coronavirus"
54125,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.086206897,"and, sars-cov-2, to, be, the"
54126,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.086206897,"by, a, the, that, and"
54127,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.086206897,"one, a, and, in, the"
54128,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.086206897,"in, and, that, the, origin"
54129,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.086206897,"at, sars-cov-2, and, to, on"
54130,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.086206897,"that, to, and, has, been"
54131,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.086206897,"to, that, sars-, cov-2, and"
54132,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.086206897,"at, that, sars-cov-2, has, been"
54133,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.086206897,"a, from, to, of, as"
54134,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.086206897,"a, of, the, to, from"
54135,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.086206897,"the, a, to, that, of"
54136,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.086206897,"the, has, that, such, and"
54137,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.086206897,"from, the, of, that, have"
54138,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.086206897,"that, not, was, from, and"
54139,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.086206897,"the, that, these, of, they"
54140,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.086206897,"bat, that, the, of, sars-cov-2"
54141,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.086206897,"the, diversity, of, which, sars-cov-2"
54142,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.086206897,"the, progenitor, viruses, of, and"
54143,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.086206897,"that, sars-cov-2, in, before, humans"
54144,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.086206897,"market, that, the, to, of"
54145,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.086206897,"and, of, the, into, humans"
54146,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.086206897,"that, of, sars-cov-2, the, huanan"
54147,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.086206897,"that, with, the, of, potential"
54148,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.086206897,"in, the, of, been, and"
54149,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.086206897,"the, and, in, from, most"
54150,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.086206897,"viruses, to, the, in, these"
54151,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.086206897,"sars-cov-2, on, and, at, to"
54152,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.086206897,"in, from, and, of, sars-cov-2"
54153,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.086206897,"sars-cov-2, to, from, and, in"
54154,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.086206897,"on, in, of, from, were"
54155,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.086206897,"the, of, and, virus,, to"
54156,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.086206897,"in, to, the, and, as"
54157,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.086206897,"that, from, a, with, sars-cov-2"
54158,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.086206897,"the, was, to, of, and"
54159,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.086206897,"the, an, of, and, from"
54160,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.086206897,"the, and, market, of, a"
54161,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.086206897,"the, of, globally,, that, to"
54162,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.086206897,"the, that, in, animals, different"
54163,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.086206897,"sars-cov-2, to, have, in, the"
54164,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.086206897,"a, of, to, the, that, first, this, is, for, as"
54165,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.086206897,"the, of, is, by, for, natural, a, to, that, genetic"
54166,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.086206897,"is, to, was, in, from"
54167,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.086206897,"and, that, not, from, was"
54168,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.086206897,"that, in, it, to, from"
54169,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.086206897,"is, that, to, and, it"
54170,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.086206897,"to, that, and, is, yet"
54171,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.086206897,"in, the, by, and, to, that, sars-cov-2, is, of, are"
54172,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.086206897,"animals, that, were, infected, with"
54173,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.086206897,"that, by, with, the, sars-cov-2"
54174,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.086206897,"that, it, to, from, in"
54175,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.086206897,",, to, in, the, that"
54176,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.086206897,"the, that, genetic, it, as"
54177,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.086206897,"evidence, to, that, the, as"
54178,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.086206897,"that, to, this, as, first, the, a, of, is, for"
54179,"Bats have been reported as being the rich source of 

coronaviruses","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.086206897,"have, as, being, the, of"
54180,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.086206897,"a, of, sars-cov-2, the, outbreak"
54181,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.086206897,"at, to, that, the, of"
54182,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.086206897,"other, that, to, the, of"
54183,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.086206897,"coronaviruses, to, that, of, and"
54184,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.086206897,"that, all, and, have, in"
54185,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.086206897,"the, of, and, in, host"
54186,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.086206897,"that, to, a, coronavirus, the"
54187,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.086206897,"the, that, a, and, to"
54188,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.086206897,"that, a, the, of, majority"
54189,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.086206897,"in, the, of, a, to, with, were, and, density, that"
54190,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.086206897,"that, had, the, virus, in"
54191,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.086206897,"that, the, of, virus, or"
54192,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.086206897,"of, in, which, the, to"
54193,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.086206897,"of, the, and, other, relationship"
54194,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.086206897,"the, cases, and, of, to"
54195,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.086206897,"and, this, in, the, to"
54196,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.086206897,"this, to, the, of, and"
54197,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.086206897,"the, from, an, and, of"
54198,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.086206897,"from, the, of, that, to"
54199,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.086206897,"the, of, coronavirus, from, that"
54200,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.086206897,"the, that, of, is, an"
54201,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.086206897,"a, the, as, is, and"
54202,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.086206897,"the, that, sars-cov-2, is, as"
54203,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.086206897,"bat, the, with, that, for"
54204,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Bats have been reported as being the rich source of 

coronaviruses",0.086206897,"of, have, the, being, as"
54205,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Bats have been reported as being the rich source of 

coronaviruses",0.086206897,"as, the, of, have, been"
54206,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.086206897,"a, virus, to, of, and"
54207,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.086206897,"a, of, and, the, to"
54208,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.086206897,"the, and, of, to, between"
54209,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.086206897,"the, to, of, virus,, and"
54210,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.086206897,"in, bats, are, to, and"
54211,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.086206897,"have, the, to, a, and"
54212,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.086206897,"have, and, in, to, the"
54213,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.086206897,"in, a, to, infected, that"
54214,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.086206897,"to, the, of, that, covid-19"
54215,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.086206897,"of, the, in, is, and"
54216,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.086206897,"covid-19, in, the, originated, but"
54217,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.086206897,"and, the, to, that, natural"
54218,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.086206897,"in, more, to, that, and"
54219,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.086206897,"in, the, and, that, to"
54220,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.086206897,"the, was, involved, of, and"
54221,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.086206897,"with, the, and, bat, cov"
54222,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.086206897,"human, sars-cov, and, bat, a"
54223,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.086206897,"is, a, and, the, as"
54224,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.086206897,"the, is, of, natural, a"
54225,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.086206897,"natural, the, of, and, is"
54226,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.086206897,"the, of, a, with, bat"
54227,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.086206897,"the, of, is, a, for"
54228,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.086206897,"that, be, sars-cov-2, to, the"
54229,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.086206897,"in, it, that, the, infected"
54230,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.086206897,"a, that, with, infected, the"
54231,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.086206897,"the, that, from, civets, hosts"
54232,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.086206897,"the, of, be, that, reservoirs"
54233,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.086206897,"the, which, that, was, to"
54234,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.086206897,"can, to, for, sars-cov, the"
54235,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.086206897,"genome, sars-cov, the, of, bat"
54236,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.086206897,"of, for, to, be, coronavirus"
54237,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.086206897,"the, was, and, involved, of"
54238,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.086206897,"and, sars-cov, bats, recombination, of"
54239,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.086206897,"the, beta, was, to, and"
54240,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.086206897,"the, of, rbd, to, was"
54241,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.086206897,"found, to, and, the, of"
54242,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.086206897,"the, to, be, rbd, of"
54243,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.086206897,"that, the, beta, and, sars-cov-2"
54244,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.086206897,"the, of, et, that, to"
54245,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.086206897,"viruses, the, in, of, a"
54246,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.086206897,"bats, recombination, sars-cov, of, and"
54247,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.086206897,"that, of, and, sars-cov, receptor"
54248,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.086206897,"and, in, found, the, are"
54249,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.086206897,"sars-cov-2, and, that, of, is"
54250,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.086206897,"of, had, to, and, the"
54251,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.086206897,"of, the, and, to, virus"
54252,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.086206897,"the, coronavirus, was, and, with"
54253,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.086206897,"other, the, relationship, of, and"
54254,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.086206897,"by, and, in, the, of"
54255,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.086206897,"and, analysis, showed, of, in"
54256,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.086206897,"the, virus, in, and, from"
54257,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.086206897,"of, covid-19, with, to, the"
54258,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.086206897,"to, the, and, that, coronaviruses"
54259,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.086206897,"with, of, for, bats,, and"
54260,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.086206897,"the, of, to, a, sars-cov"
54261,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.086206897,"and, the, novel, to, of"
54262,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.086206897,"bats, a, of, the, coronaviruses"
54263,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.086206897,"the, of, to, or, coronaviruses"
54264,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.086206897,"the, genomic, of, that, coronavirus"
54265,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.086206897,"of, the, and, has, with"
54266,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.086206897,"the, of, and, novel, coronavirus"
54267,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.086206897,"the, and, to, of, bat"
54268,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.086206897,"and, novel, to, the, of"
54269,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.086206897,"that, a, the, sars-cov-2, and"
54270,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.086206897,"sars-cov-2, a, and, that, the"
54271,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.086206897,"the, between, and, is, bat"
54272,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.086206897,"the, and, are, direct, of"
54273,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.086206897,"the, genome, of, bat, sars-cov"
54274,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.086206897,"in, a, that, virus, from"
54275,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.086206897,"were, of, from, in, on"
54276,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.086206897,"the, that, of, coronavirus, from"
54277,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.086206897,"the, of, from, were, in"
54278,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.086206897,"a, genome, that, the, of"
54279,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.086206897,"the, sequence, of, that, viruses"
54280,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.086206897,"the, genome, indicate, that, are"
54281,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.086206897,"of, animals, revealed, that, for"
54282,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.086206897,"the, of, huanan, that, sars-cov-2"
54283,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.086206897,"of, that, the, from, for"
54284,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.086206897,"be, that, a, sars-cov-2, coronavirus"
54285,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.086206897,"that, sars-cov-2, to, bat, as"
54286,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.086206897,"that, is, to, bat, and"
54287,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.086206897,"receptor, and, that, sars-cov, of"
54288,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.086206897,"ace2, of, sars-cov-2, and, the"
54289,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.086206897,"the, of, sequences, that, at"
54290,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.086206897,"was, that, the, to, which"
54291,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.086206897,"the, of, et, to, that"
54292,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.086206897,"to, the, which, that, may"
54293,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.086206897,"et, al., of, which, to"
54294,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.086206897,"that, has, been, and, to"
54295,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.086206897,"that, it, to, and, is"
54296,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.086206897,"a, the, of, is, that"
54297,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.086206897,"of, the, in, a, to"
54298,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.086206897,"a, as, the, of, and"
54299,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.086206897,"which, the, in, its, pangolin"
54300,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.086206897,"the, have, of, and, recent"
54301,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.086206897,"have, the, and, to, a"
54302,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.086206897,"the, a, of, found, coronaviruses"
54303,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.086206897,"coronaviruses, a, the, bats, of"
54304,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.086206897,"bats, are, the, of, china"
54305,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.086206897,"of, to, in, sars-cov-2, the"
54306,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.086206897,"the, and, in, to, of"
54307,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.086206897,"of, and, for, with, bats,"
54308,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.086206897,"a, of, for, were, with"
54309,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.086206897,"who, in, that, the, related, to, of, covs, were, found"
54310,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.086206897,"coronaviruses, to, the, of, or"
54311,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.086206897,"the, been, to, by, and"
54312,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.086206897,"sequences, from, bats, of, species"
54313,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.086206897,"the, sequences, to, sars-, cov-2"
54314,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.086206897,"with, a, that, sars-cov-2, from"
54315,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.086206897,"the, to, coronavirus, that, a"
54316,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.086206897,"in, the, from, a, malayan"
54317,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.086206897,"in, that, the, an, of"
54318,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.086206897,"coronaviruses, sars-cov-2, in, the, of"
54319,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.086206897,"from, as, to, and, the"
54320,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.086206897,"the, in, as, to, and"
54321,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.086206897,"the, of, sars-cov-2, and, ace2"
54322,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.086206897,"of, sars-cov-2,, that, 2019, with"
54323,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.086206897,"and, in, most, the, from"
54324,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.086206897,"is, found, to, the, most"
54325,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.086206897,"the, natural, to, that, and"
54326,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.086206897,"the, of, natural, as, and"
54327,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.086206897,"intermediate, species, and, in, the"
54328,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.086206897,"that, as, may, sars-cov-2, in"
54329,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.086206897,"the, residues, of, a, with"
54330,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.086206897,"the, to, sars-cov-2, intermediate, and"
54331,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.086206897,"intermediate, and, humans, in, the"
54332,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.086206897,"that, to, found, in, and"
54333,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.086206897,"that, may, to, variants, in"
54334,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.086206897,"that, the, and, has, been"
54335,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.086206897,"the, was, to, beta, and"
54336,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.086206897,"beta, that, the, sars-cov-2, and"
54337,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.086206897,"to, the, of, and, may"
54338,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.086206897,"the, of, and, sars-cov-2, humans"
54339,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.086206897,"the, of, covid-19, in, to"
54340,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.086206897,"that, the, sequences, of, at"
54341,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.086206897,"coronaviruses, to, the, that, and"
54342,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.086206897,"from, the, to, a, that, with, and, could, in, of"
54343,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.086206897,"coronaviruses, bats, which, are, of"
54344,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.086206897,"that, the, majority, of, a"
54345,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.086206897,"of, the, that, virus, or"
54346,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.086206897,"a, at, the, is, sars-cov-2’s"
54347,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.086206897,"a, the, natural, of, is"
54348,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.086206897,"of, the, sars-cov-2, diversity, which"
54349,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.086206897,"of, the, and, progenitor, viruses"
54350,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.086206897,"and, intermediate, sars-cov-2, to, the"
54351,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.086206897,"in, viruses, and, the, sars"
54352,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.086206897,"in, the, of, and, an"
54353,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.086206897,"to, of, in, the, and"
54354,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.086206897,"the, by, between, and, this"
54355,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.086206897,"bat, and, the, same, are"
54356,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.086206897,"bat, to, as, genetic, the"
54357,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.086206897,"the, that, to, a, bat"
54358,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.086206897,"of, to, a, bat, in"
54359,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.086206897,"that, are, the, to, with, in, this, appears, of, and"
54360,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.086206897,"the, bat, as, to, genetic"
54361,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.086206897,"at, the, similar, to, sars-cov-2,"
54362,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.086206897,"are, the, coronaviruses,, and, other"
54363,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.086206897,"in, it, the, and, sars-cov-2"
54364,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.086206897,"are, of, and, to, that"
54365,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.086206897,"that, to, the, by, a, of, genetic, is, for, natural"
54366,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.086206897,"to, of, the, that, with"
54367,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.086206897,"the, of, that, through, than"
54368,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.086206897,"also, the, of, is, in"
54369,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.086206897,"the, is, to, and, a"
54370,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.086206897,"is, a, the, at, sars-cov-2’s"
54371,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.086206897,"most, the, of, is, to"
54372,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.086206897,"in, the, bat, these, and"
54373,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.086206897,"it, that, the, infected, in"
54374,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.086206897,"it, in, and, sars-cov-2, the"
54375,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.086206897,"and, sars-cov-2, in, is, the"
54376,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.086206897,"the, case, of, sars-cov-2,, were"
54377,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.086206897,"2019, with, sars-cov-2,, that, of"
54378,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.086206897,"by, and, to, the, of"
54379,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.086206897,"to, the, by, from, and"
54380,"t some virus detected in pangolins 

were capable of infecting humans.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.086206897,"virus, in, were, of, humans."
54381,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.086206897,"the, to, identical, in, and"
54382,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.086206897,"several, coronaviruses, found, in, horseshoe, bats, to, that, of, and"
54383,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.086206897,"of, had, a, to, any, other, and, the, were, in"
54384,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.086206897,"to, could, from, a, of, in, the, and, that, with"
54385,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.086206897,"the, by, of, in, receptor, and, that, this, coronavirus, a"
54386,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.086206897,"that, the, of, were, in, to, with, a, density, and"
54387,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.086206897,"the, had, of, and, to"
54388,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.086206897,"in, a, of, to, the, and, had, were, any, other"
54389,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.086206897,"a, the, covid-19, of, and"
54390,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.086206897,"the, of, with, other, to"
54391,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.086206897,"the, market, and, a, of"
54392,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.086206897,"to, the, is, of, natural"
54393,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.086206897,"a, of, the, to, origin"
54394,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.086206897,"the, and, in, this, to"
54395,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.086206897,"the, that, all, also, and"
54396,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.086206897,"one, of, these, sequences, in"
54397,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.086206897,"the, to, of, between, and"
54398,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.086206897,"that, the, infected, with, a"
54399,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.086206897,"the, found, is, most, to"
54400,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.086206897,"found, in, and, to, that"
54401,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.086206897,"of, to, a, in, the"
54402,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.086206897,"natural, and, a, zoonotic, in"
54403,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.086206897,"the, sars-cov-2, a, in, bat"
54404,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.086206897,"human, of, this, natural, the"
54405,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.086206897,"the, to, that, human, sars-cov-2"
54406,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.086206897,"this, is, the, sars-cov-2, that"
54407,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.086206897,"the, to, of, is, bat"
54408,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.086206897,"the, that, to, it, from"
54409,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.086206897,"the, which, that, may, to"
54410,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.086206897,"a, to, which, in, the"
54411,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.086206897,"is, from, to, human, in"
54412,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.086206897,"sars-cov-2, to, pangolin, coronaviruses, in"
54413,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.086206897,",, the, that, in, to"
54414,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.086206897,"the, of, coronaviruses, in, sars-cov-2"
54415,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.086206897,"the, was, to, rbd, of"
54416,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.086206897,"of, more, and, with, or"
54417,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.086206897,"with, the, of, and, from"
54418,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.086206897,"the, of, sars-cov-2, a, or"
54419,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.086206897,"and, that, of, observed, in"
54420,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.086206897,"in, is, sars-cov-2, the, of"
54421,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.086206897,"from, is, to, in, human"
54422,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.086206897,"bats, the, of, and, in"
54423,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.086206897,"the, of, mers-cov, to, and"
54424,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.086206897,"that, of, from, the, for"
54425,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.086206897,"of, the, from, origin, is"
54426,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.086206897,"the, of, that, sequence, viruses"
54427,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.086206897,"in, to, be, that, are"
54428,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.086206897,"is, and, bat, to, that"
54429,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.086206897,"the, that, of, been, a"
54430,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.086206897,"all, that, have, in, and"
54431,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.086206897,"in, the, that, animals, with"
54432,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.086206897,"in, different, the, that, animals"
54433,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.086206897,"to, have, with, the, of"
54434,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.086206897,"the, of, with, that, in"
54435,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.086206897,"to, contact, with, of, in"
54436,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.086206897,"to, in, contact, with, of"
54437,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.086206897,"to, bats, be, direct, of"
54438,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.086206897,"in, species, and, the, intermediate"
54439,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.086206897,"and, intermediate, humans, the, in"
54440,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.086206897,"to, as, a, of, from"
54441,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.086206897,"a, of, to, and, virus"
54442,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.086206897,"bats, are, a, of, and"
54443,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.086206897,"can, be, and, of, bat"
54444,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.086206897,"and, bat, some, to, of"
54445,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.086206897,"are, to, or, bats, be"
54446,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.086206897,"or, bats, are, to, be"
54447,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.086206897,"have, the, of, and, from"
54448,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.086206897,"of, the, is, origin, from"
54449,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","t some virus detected in pangolins 

were capable of infecting humans.",0.086206897,"of, were, virus, in, humans."
54450,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.086206897,"of, covid-19, a, and, the"
54451,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.086206897,"the, which, to, a, is"
54452,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.086206897,"from, of, 41, species, and"
54453,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.086206897,"of, also, to, the, animals"
54454,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.086206897,"and, some, to, the, of"
54455,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.086206897,"that, has, and, such, the"
54456,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.086206897,"the, from, civets, that, hosts"
54457,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.086206897,"the, of, to, and, mers-cov"
54458,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.086206897,"the, and, a, one, in"
54459,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.086206897,"coronavirus, in, the, with, other"
54460,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.086206897,"sars-cov-2, be, a, the, and"
54461,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.086206897,"to, a, virus, that, the"
54462,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.086206897,"the, of, a, origin, to"
54463,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.086206897,"to, that, the, of, origin"
54464,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.086206897,"coronavirus, with, other, in, the"
54465,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.086206897,"sars-cov-2, to, a, in, bat"
54466,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.086206897,"a, that, from, to, bat"
54467,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.086206897,"the, is, that, of, with"
54468,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.086206897,"sars-cov-2, may, in, that, as"
54469,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.086206897,"in, variants, to, that, may"
54470,"Bats have been reported as being the rich source of 

coronaviruses","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.086206897,"have, been, as, the, of"
54471,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.086206897,"the, are, of, that, these"
54472,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.086206897,"these, that, they, the, of"
54473,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.086206897,"genetic, the, that, as, it"
54474,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.086206897,"sars-cov-2, is, that, the, as"
54475,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.086206897,"sars-cov-2, is, the, with, or"
54476,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.086206897,"as, and, the, of, natural"
54477,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.086206897,"have, the, in, and, to"
54478,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.086206897,"and, by, the, in, of"
54479,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.086206897,"of, and, by, in, the"
54480,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.086206897,"to, and, of, is, in"
54481,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.086206897,"its, in, the, which, pangolin"
54482,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.086206897,"coronaviruses, that, of, to, and"
54483,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.086206897,"are, and, bats, to, in"
54484,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.086206897,"more, to, that, in, and"
54485,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.086206897,"bats, are, of, coronaviruses, which"
54486,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.086206897,"to, bats, several, and, in, of, horseshoe, that, coronaviruses, found"
54487,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.086206897,"that, bats, sars-cov-2, based, on"
54488,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.086206897,"amino, acid, of, more, to"
54489,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.086206897,"that, the, and, to, from"
54490,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.086206897,"this, and, by, between, the"
54491,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.086206897,"the, by, from, and, to"
54492,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.086206897,"to, and, is, that, ratg13"
54493,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.086206897,"of, with, to, other, the"
54494,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.086206897,"of, also, the, to, animals"
54495,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.086206897,"was, in, the, to, of"
54496,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.086206897,"the, that, a, also, coronavirus"
54497,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.086206897,"and, the, of, appears, to, are, with, that, this, in"
54498,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.086206897,"yet, that, to, and, is"
54499,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.086206897,"the, of, and, this, to"
54500,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.086206897,"the, natural, of, is, and"
54501,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.086206897,"of, the, that, to, origin"
54502,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.086206897,"bats, that, sars-cov-2, based, on"
54503,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.086206897,"that, the, bat, a, to"
54504,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.086206897,"the, that, and, all, also"
54505,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.086206897,"the, coronavirus, also, a, that"
54506,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.086206897,"contains, the, a, to, that"
54507,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.086206897,"genome, that, the, virus, bats"
54508,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.086206897,"were, from, bats, of, by"
54509,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.086206897,"a, of, the, genome, that"
54510,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.086206897,"of, the, to, related, who, in, were, found, that, covs"
54511,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.086206897,"the, genome, that, bats, virus"
54512,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.086206897,"a, the, of, sars-cov-2, outbreak"
54513,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.086206897,"sars-cov-2, in, a, of, the"
54514,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.086206897,"of, bat, in, a, to"
54515,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.086206897,"of, sequences, these, in, one"
54516,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.086206897,"of, et, al., which, to"
54517,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.086206897,"2, and, of, the, virus"
54518,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.086206897,"the, that, with, sars-cov-2, by"
54519,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.086206897,"of, the, novel, coronavirus, and"
54520,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.086206897,"through, that, the, of, than"
54521,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.086206897,"the, a, that, this, receptor, and, by, in, of, coronavirus"
54522,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.086206897,"the, be, to, that, and"
54523,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.086206897,"that, the, and, for, to"
54524,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.086206897,"the, and, genome, to, that"
54525,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.086206897,"the, with, that, sars-cov-2, at"
54526,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.086206897,"the, for, with, that, bat"
54527,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.086206897,"the, sars-cov-2, is, that, this"
54528,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.086206897,"has, been, the, and, that"
54529,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.086206897,"the, sars, and, viruses, in"
54530,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.086206897,"the, in, that, bat, origin"
54531,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.086206897,"in, the, sars-cov-2, have, to"
54532,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.086206897,"the, with, sars-cov-2, is, or"
54533,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.086206897,"the, that, to, are, in, is, by, of, and, sars-cov-2"
54534,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.086206897,"and, are, bat, the, same"
54535,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.086206897,"the, of, virus, genome, from"
54536,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.086206897,"in, these, the, bat, and"
54537,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.086206897,"and, of, between, in, the"
54538,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.086206897,"to, the, of, other, that"
54539,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.086206897,"the, found, to, of, and"
54540,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.086206897,"a, the, of, bat, with"
54541,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.086206897,"from, a, in, malayan, the"
54542,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.086206897,"that, of, bats, a, the"
54543,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.086206897,"a, bats, of, and, are"
54544,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.086206897,"a, that, the, of, bats"
54545,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.086206897,"in, the, identical, to, and"
54546,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.086206897,"natural, of, and, that, in"
54547,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.086206897,"and, to, the, of, with"
54548,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.086206897,"that, of, an, in, the"
54549,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.086206897,"can, be, bat, of, and"
54550,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.086206897,"the, of, that, from, to"
54551,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.086206897,"of, that, the, new, in"
54552,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.086206897,"direct, to, be, of, bats"
54553,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.086206897,"a, of, residues, the, with"
54554,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.086206897,"in, bat, that, the, origin"
54555,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.086206897,"sars-cov-2, be, of, the, and"
54556,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.086206897,"a, the, between, and, suggesting"
54557,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.086206897,"a, and, sars-cov-2, be, the"
54558,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.086206897,"and, sars-cov-2, cov, the, between"
54559,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.086206897,"that, sars-cov-2, has, been, at"
54560,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.086206897,"a, for, the, of, is"
54561,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.086206897,"the, animal, that, sars-cov-2, in"
54562,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.086206897,"in, but, the, covid-19, originated"
54563,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.086206897,"that, a, the, for, sars-cov-2"
54564,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.086206897,"of, suggesting, that, sars-cov-2, to"
54565,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.086206897,"that, in, to, infected, a"
54566,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.086206897,"of, coronavirus, to, for, be"
54567,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.086206897,"with, of, were, a, for"
54568,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.086206897,"of, and, are, to, that"
54569,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.086206897,"a, natural, and, in, zoonotic"
54570,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.086206897,"that, natural, in, and, of"
54571,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.086206897,"to, sars-cov-2,, similar, at, the"
54572,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.086206897,"the, that, to, a, contains"
54573,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.086206897,"and, are, the, of, direct"
54574,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.086206897,"and, in, to, of, is"
54575,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.086206897,"is, to, that, ratg13, and"
54576,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.086206897,"one, study, of, that, with"
54577,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.086206897,"the, of, potential, with, that"
54578,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.086206897,"more, to, of, amino, acid"
54579,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.086206897,"of, to, pangolin, sars-cov-2, the"
54580,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.086206897,"bat, to, of, and, some"
54581,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.086206897,"of, some, and, the, to"
54582,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.086021505,"in, of, to, bats, which, and, more, than"
54583,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.086021505,"of, the, resulting, in, a, to, that, such"
54584,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.086021505,"the, are, to, of, viruses, emergence, that, and"
54585,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.086021505,"that, it, to, this, the, animal, of, is"
54586,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.086021505,"the, animal, of, to, a, coronavirus, is, and"
54587,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.086021505,"the, are, of, most, that, bats, by, and"
54588,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.086021505,"this, that, a, the, of, at, least, to"
54589,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.086021505,"to, in, of, hong, kong, on, were, and"
54590,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.086021505,"the, that, was, to, more, than, of, and"
54591,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.086021505,"from, to, samples, the, in, early, of, a"
54592,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.086021505,"the, of, that, to, animal, it, is, this"
54593,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.086021505,"the, other, of, sars-cov-2,, in, and, andersen,, laboratory"
54594,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.086021505,"more, than, of, the, to, and, that, was"
54595,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.086021505,"the, in, of, to, that, sars-cov-2, can, was"
54596,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.086021505,"that, were, infected, the, wet, at, animals, on"
54597,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.086021505,"in, the, to, that, is, of, are, as"
54598,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.086021505,"and, in, were, found, that, the, of, is"
54599,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.086021505,"from, the, also, virus, that, this, and, taken"
54600,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.086021505,"the, to, of, horseshoe, is, that, virus, and"
54601,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.086021505,"may, the, of, that, virus, to, is, and"
54602,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.086021505,"for, and, with, the, of, on, a, positive"
54603,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.086021505,"sars-cov-2, of, the, been, to, over, bat, coronavirus"
54604,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.086021505,"and, all, a, or, that, is, sars-cov-2, animal"
54605,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.086021505,"the, of, that, virus, to, indicated, coronavirus, and"
54606,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.086021505,"the, of, with, available, was, virus, and, other"
54607,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.086021505,"and, the, of, different, with, in, mutation, virus"
54608,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.086021505,"and, the, of, bat, a, with, in, virus"
54609,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.086021505,"the, that, in, for, of, identified, were, a"
54610,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.086021505,"the, to, a, of, is, that, virus, and"
54611,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.086021505,"the, of, a, in, to, that, with, similar"
54612,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.086021505,"and, the, of, to, viruses, as, a, which"
54613,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.086021505,"the, a, in, with, intermediate, were, it, for"
54614,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.086021505,"the, of, sars-cov-2, been, over, to, coronavirus, bat"
54615,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.086021505,"animal, to, sars-cov-2, were, live, and, in, the"
54616,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.086021505,"in, a, of, yunnan, bat, similarity, genome, virus"
54617,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.086021505,"sars-cov-2, and, the, to, live, animal, in, were"
54618,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.086021505,"this, that, the, was, early, of, in, at"
54619,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.086021505,"that, the, sars-cov-2, to, with, in, of, and"
54620,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.086021505,"the, to, in, a, of, is, progenitor, virus"
54621,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.086021505,"bat, to, as, the, of, and, species, horseshoe"
54622,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.086021505,"the, to, sars-related, bat, and, in, of, an"
54623,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.086021505,"of, the, virus, in, different, with, and, mutation"
54624,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.086021505,"a, and, with, the, of, virus, bat, in"
54625,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.086021505,"the, of, to, a, and, which, as, viruses"
54626,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.086021505,"the, to, that, experiments, with, ace2, human, of"
54627,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.086021505,"a, at, least, to, that, the, of, this"
54628,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.086021505,"the, of, in, early, that, this, was, at"
54629,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.086021505,"is, to, a, of, animal, coronavirus, and, the"
54630,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.086021505,"is, that, the, virus, and, may, of, to"
54631,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.086021505,"indicated, that, the, virus, of, coronavirus, and, to"
54632,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.086021505,"in, with, the, and, to, that, of, as"
54633,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.086021505,"were, a, intermediate, for, it, with, the, in"
54634,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.086021505,"and, in, to, bats, of, more, than, which"
54635,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.086021505,"a, bat, virus, in, yunnan, genome, similarity, of"
54636,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.086021505,"bats, the, most, for, to, a, bat, coronavirus."
54637,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.086021505,"that, taken, from, the, and, also, this, virus"
54638,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.086021505,"bat, and, to, an, in, the, of, sars-related"
54639,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.086021505,"experiments, that, the, of, with, to, human, ace2"
54640,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.086021505,"in, yunnan, was, similar, to, that, of, the"
54641,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.086021505,"the, horseshoe, species, to, as, of, bat, and"
54642,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.086021505,"an, species, and, in, all, by, the, palm"
54643,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.086021505,"a, bat, of, by, at, the, in, china"
54644,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.086021505,"to, the, of, from, zoonotic, by, a, virus"
54645,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.086021505,"the, on, wet, animals, that, infected, were, at"
54646,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.086021505,"the, viruses, and, are, of, that, to, emergence"
54647,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.086021505,"that, bats, and, are, the, of, most, by"
54648,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.086021505,"were, of, in, hong, kong, and, to, on"
54649,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.086021505,"the, virus, is, to, that, of, and, horseshoe"
54650,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.086021505,"of, the, virus, and, other, available, was, with"
54651,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.086021505,"the, is, of, to, a, progenitor, virus, in"
54652,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.086021505,"the, and, market, is, one, of, a, to"
54653,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.086021505,"the, that, virus, in, animals, with, were, captured"
54654,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.086021505,"to, that, emergence, the, most, of, and, is"
54655,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.086021505,"the, of, that, are, likely, to, a, with"
54656,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.086021505,"samples, from, early, in, the, of, a, to"
54657,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.086021505,"a, for, the, on, positive, of, and, with"
54658,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.086021505,"identified, in, the, of, a, that, were, for"
54659,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.086021505,"to, in, the, all, that, for, is, of"
54660,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.086021505,"a, of, the, chinese, by, that, have, to"
54661,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.086021505,"all, that, sars-cov-2, a, animal, and, is, or"
54662,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.086021505,"of, the, early, cases, in, that, market,, by"
54663,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.086021505,"this, a, that, the, covid-19, is, of, and"
54664,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.086021505,"the, to, a, of, one, is, and, market"
54665,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.086021505,"the, these, of, are, known, and, in, also"
54666,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.086021505,"the, is, that, in, for, of, to, all"
54667,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.086021505,"the, that, was, to, in, of, can, sars-cov-2"
54668,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.086021505,"early, cases, the, market,, of, that, in, by"
54669,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.086021505,"the, animals, in, with, that, virus, were, captured"
54670,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.086021505,"an, palm, in, the, by, all, and, species"
54671,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.086021505,"the, of, known, are, and, these, in, also"
54672,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.086021505,"the, and, of, a, that, covid-19, this, is"
54673,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.086021505,"the, that, have, of, to, by, chinese, a"
54674,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.086021505,"and, from, in, to, that, the, of, sars-cov-2"
54675,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.086021505,"the, to, of, is, most, emergence, that, and"
54676,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.086021505,"a, to, the, bats, for, coronavirus., bat, most"
54677,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.086021505,"at, bat, a, in, the, by, china, of"
54678,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.086021505,"andersen,, in, the, of, and, other, sars-cov-2,, laboratory"
54679,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.086021505,"in, of, to, the, are, that, is, as"
54680,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.086021505,"the, of, and, that, in, with, as, to"
54681,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.086021505,"the, are, to, a, of, with, likely, that"
54682,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.086021505,"to, a, from, the, virus, by, zoonotic, of"
54683,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.086021505,"the, was, to, that, similar, in, of, yunnan"
54684,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.086021505,"of, to, a, such, that, resulting, in, the"
54685,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.086021505,"the, of, and, in, found, that, were, is"
54686,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.086021505,"from, and, to, the, of, that, sars-cov-2, in"
54687,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.0859375,"a, the, health, at, and, in, to, with, for, that, from"
54688,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.0859375,"the, for, to, virus, used, as, and, would, in, of, at"
54689,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.0859375,"a, of, the, these, were, in, for, that, from, suggested, intermediate"
54690,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.0859375,"in, a, to, bat, as, coronaviruses, be, and, that, from, species"
54691,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.0859375,"in, the, a, that, from, to, at, and, with, for, health"
54692,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.0859375,"in, the, of, a, from, suggested, that, these, were, intermediate, for"
54693,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.0859375,"as, in, the, of, and, at, to, used, for, would, virus"
54694,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.0859375,"a, and, coronaviruses, from, bat, species, be, as, to, that, in"
54695,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.0859375,"viruses, similar, to, the, in, of, and, that, these, a, outbreak"
54696,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.0859375,"in, the, of, a, to, these, viruses, similar, and, that, outbreak"
54697,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.085714286,"a, of, presence"
54698,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.085714286,"a, and, from, that, in, bats"
54699,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.085714286,"human, are, in"
54700,"bats are also important reservoir species for a great 

range of coronaviruses",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.085714286,"are, a, coronaviruses"
54701,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.085714286,"viruses, into, 2, and, this, the"
54702,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.085714286,"coronaviruses, are, in"
54703,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.085714286,"are, the, to, be, of, and"
54704,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.085714286,"study, that, of, bats, coronavirus, with"
54705,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.085714286,"study, that, virus, of, were, bats"
54706,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.085714286,"to, bat, sars-cov"
54707,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.085714286,"have, and, such"
54708,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.085714286,"bat, and, to"
54709,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.085714286,"have, in, and"
54710,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.085714286,"and, to, bat"
54711,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.085714286,"sequences, to, sars-cov"
54712,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.085714286,"of, and, to"
54713,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.085714286,"bats, to, of"
54714,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.085714286,"of, from, bats"
54715,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.085714286,"of, from, and"
54716,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.085714286,"species, were, and"
54717,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.085714286,"more, from, of"
54718,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.085714286,"and, very, to"
54719,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.085714286,"the, sars, to"
54720,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.085714286,"the, sarbecovirus, and"
54721,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.085714286,"more, than, to"
54722,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.085714286,"sars-cov-2, is, than"
54723,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.085714286,"in, bats, china"
54724,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.085714286,"the, of, sars-cov, and, bat, to"
54725,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.085714286,"virus, from, bat, to, of, and"
54726,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.085714286,"sars-cov-2, is, a, as, to, in"
54727,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.085714286,"of, sars-cov-2, be"
54728,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.085714286,"been, that, of"
54729,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.085714286,"coronavirus, by, a"
54730,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.085714286,"sars-cov-2, be, a"
54731,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.085714286,"a, origin, of, the, that, sars-cov-2, and, in, which"
54732,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.085714286,"the, is, of, human, and, in"
54733,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.085714286,"is, virus, sars-cov-2"
54734,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.085714286,"and, many, other"
54735,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.085714286,"human, are, all"
54736,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.085714286,"the, of, that, to, human, and"
54737,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.085714286,"the, highly, as"
54738,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.085714286,"sars-cov-2, to, host"
54739,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.085714286,"bat, and, of"
54740,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.085714286,"of, including, and"
54741,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.085714286,"the, reservoir, and"
54742,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.085714286,"a, of, and"
54743,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.085714286,"a, of, including"
54744,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.085714286,"showed, and, identity, sars-cov-2, to, the"
54745,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.085714286,"sars-cov-2, and, with"
54746,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.085714286,"are, most, of"
54747,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.085714286,"sars-cov-2, to, most"
54748,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.085714286,"between, sars-cov-2, and, of, the, have, to, animal, that"
54749,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",hese reservoirs are the bats,0.085714286,"the, bats, reservoirs"
54750,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.085714286,"the, as, host"
54751,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.085714286,"in, the, of, that, to, virus"
54752,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.085714286,"a, is, to, in, the, that"
54753,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.085714286,"similarity, to, in"
54754,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.085714286,"highly, as, the"
54755,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.085714286,"in, the, sars-cov-2,"
54756,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.085714286,"of, to, the, from, for, as"
54757,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.085714286,"the, for, spillover, of, sars-cov-2, from"
54758,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.085714286,"in, the, to, that, is, of"
54759,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.085714286,"and, to, animal"
54760,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.085714286,"were, seafood, and"
54761,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.085714286,"a, in, to"
54762,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.085714286,"and, linked, to"
54763,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.085714286,"were, a, in"
54764,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.085714286,"to, transmission, be"
54765,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.085714286,"bats, be, the"
54766,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.085714286,"and, of, major"
54767,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.085714286,"of, the, early"
54768,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.085714286,"the, was, other"
54769,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.085714286,"regions, the, in"
54770,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.085714286,"from, the, china"
54771,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.085714286,"from, in, china"
54772,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.085714286,"that, is, in"
54773,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.085714286,"of, sars-cov-2, bat"
54774,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.085714286,"the, for, viral"
54775,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.085714286,"to, for, the, animals, at, that"
54776,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.085714286,"that, a, the, was, humans, with, in, at, to"
54777,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.085714286,"be, of, sars-cov-2"
54778,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.085714286,"to, the, animal"
54779,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.085714286,"the, pangolins,, sars-cov-2"
54780,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","with the first case being linked to  

a seafood market",0.085714286,"the, case, first"
54781,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.085714286,"has, in, bats"
54782,"t some virus detected in pangolins 

were capable of infecting humans.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.085714286,"in, pangolins, of"
54783,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.085714286,"a, the, by"
54784,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.085714286,"a, the, which"
54785,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.085714286,"which, in, the"
54786,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.085714286,"a, the, been"
54787,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.085714286,"the, virus, other"
54788,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.085714286,"such, have, and"
54789,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.085714286,"zoonotic, sars-cov-2, from"
54790,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.085714286,"sars-cov-2, likely, with"
54791,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.085714286,"sars-cov-2, origin, of, which, a, that, in, and, the"
54792,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.085714286,"the, sars-cov-2, in, from, of, a"
54793,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.085714286,"sars-cov-2, host, zoonotic"
54794,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.085714286,"zoonotic, animals, humans"
54795,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.085714286,"the, of, market"
54796,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.085714286,"animals, the, market"
54797,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.085714286,"to, infection, and"
54798,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.085714286,"the, of, that, in, primary, and"
54799,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.085714286,"at, market, in, that, the, of"
54800,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.085714286,"more, in, the"
54801,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.085714286,"the, show, that"
54802,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.085714286,"the, was, than"
54803,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.085714286,"from, on, and, were, in, of, to, at, least"
54804,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.085714286,"a, from, spillover"
54805,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.085714286,"and, to, was, the, of, that"
54806,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.085714286,"the, of, sars-cov-2, and, both, a"
54807,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor",0.085714286,"sars-cov-2, to, possible"
54808,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.085714286,"that, the, of, sars-cov-2, two, a"
54809,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.085714286,"of, and, are, to, be, the"
54810,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.085714286,"that, a, is"
54811,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.085714286,"the, genome, to"
54812,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.085714286,"to, the, of, from, as, for"
54813,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.085714286,"in, from, of, were, to, the"
54814,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.085714286,"have, a, of, in, the, as"
54815,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.085714286,"we, find, that, the, is, same"
54816,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.085714286,"the, of, raccoon, in, that, at"
54817,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.085714286,"the, in, of, that, we, virus"
54818,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.085714286,"of, a, that, the, virus, and"
54819,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.085714286,"to, in, spillover"
54820,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.085714286,"animal, to, in"
54821,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.085714286,"evidence, that, in"
54822,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.085714286,"the, that, animals, to, at, for"
54823,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.085714286,"of, animals,, and"
54824,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.085714286,"of, as, from"
54825,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.085714286,"a, that, with, the, to, virus"
54826,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.085714286,"the, and, on"
54827,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.085714286,"of, a, and"
54828,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.085714286,"a, to, have"
54829,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.085714286,"that, of, coronaviruses"
54830,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.085714286,"that, species, of"
54831,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.085714286,"in, have, and"
54832,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.085714286,"the, and, was"
54833,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.085714286,"the, of, sars-cov,"
54834,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.085714286,"and, disease, is"
54835,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.085714286,"the, was, and"
54836,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.085714286,"the, of, pandemic"
54837,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.085714286,"of, a, with"
54838,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.085714286,"in, the, that, of, to, market"
54839,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.085714286,"in, the, across"
54840,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.085714286,"cases, the, huanan, of, in, by"
54841,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.085714286,"the, of, and, as, et, n"
54842,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Bats have been reported as being the rich source of 

coronaviruses",0.085714286,"bats, have, the"
54843,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.085714286,"have, a, to"
54844,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.085714286,"the, a, coronavirus"
54845,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.085714286,"the, has, a"
54846,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.085714286,"has, the, with"
54847,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.085714286,"pangolins, of, their"
54848,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.085714286,"bat, sars-cov-2, the"
54849,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.085714286,"to, the, human"
54850,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.085714286,"bat, to, intermediate"
54851,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.085714286,"the, animal, of, that, was, to, by, is, and"
54852,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.085714286,"the, and, a, to, that, in, infected, at, market"
54853,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.085714286,"the, and, to, in, virus, genetic"
54854,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.085714286,"believe, the, to"
54855,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.085714286,"zoonotic, to, through"
54856,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.085714286,"the, of, and, in, are, to"
54857,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.085714286,"of, bats, to, is, in, the"
54858,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.085714286,"to, in, genetic"
54859,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.085714286,"show, that, to"
54860,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.085714286,"that, virus, of"
54861,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.085714286,"on, and, to, or, may, be"
54862,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.085714286,"the, of, and, sars-cov, as, a"
54863,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.085714286,"the, market, animals"
54864,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.085714286,"wild, infected, the"
54865,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.085714286,"the, reported, in"
54866,"Recently released  

findings included raccoon dog  

DNA, pointing to a possible  

SARS-CoV-2 progenitor","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.085714286,"to, possible, sars-cov-2"
54867,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.085714286,"analysis, revealed, the"
54868,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.085714286,"that, hosts, for"
54869,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.085714286,"a, of, researchers, the, bats, coronavirus, bat, novel, viruses"
54870,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.085714286,"previous, the, of"
54871,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.085714286,"than, the, animal, of, for, similar, to, coronavirus, is"
54872,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.085714286,"the, for, of, to, is, animal, more, be, than"
54873,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.085714286,"be, of, the, similar, to, s"
54874,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.085714286,"analysis, the, of, suggested, for, cross-species"
54875,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.085714286,"the, to, for, of, as, with, was, bats, and"
54876,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.085714286,"the, with, of, or, as, for"
54877,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.085714286,"to, spillover, humans"
54878,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.085714286,"in, spillover, to"
54879,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.085714286,"in, can, and"
54880,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.085714286,"that, the, of, and, as, sars-cov-2"
54881,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.085714286,"that, of, been"
54882,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.085714286,"that, bat, the"
54883,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.085714286,"of, the, from"
54884,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.085714286,"the, reservoir, that"
54885,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.085714286,"coronaviruses, that, of"
54886,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.085714286,"are, the, from"
54887,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.085714286,"from, the, has"
54888,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.085714286,"the, from, that"
54889,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.085714286,"between, sars-cov-2, and, of, the, have, to, that, bat"
54890,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.085714286,"have, shown, that"
54891,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.085714286,"to, sars-cov-2, several"
54892,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.085714286,"the, in, regions"
54893,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.085714286,"he, protein, of"
54894,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.085714286,"the, regions, of, a, in, isolated"
54895,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.085714286,"sars-cov, and, by, of, that, have"
54896,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.085714286,"that, is, likely"
54897,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.085714286,"the, most, virus"
54898,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.085714286,"the, has, bats"
54899,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",Many of these CoVs can infect several animal species as well,0.085714286,"can, these, several, species, of, as"
54900,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.085714286,"that, from, a"
54901,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.085714286,"to, the, for"
54902,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.085714286,"to, the, animals"
54903,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.085714286,"the, for, a"
54904,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.085714286,"from, bats, of"
54905,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.085714286,"the, also, bats"
54906,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.085714286,"the, in, are"
54907,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.085714286,"and, is, that"
54908,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.085714286,"a, origin, and"
54909,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.085714286,"has, bats, in"
54910,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.085714286,"most, bats, in"
54911,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.085714286,"t, the, that"
54912,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.085714286,"the, of, was, virus, and, sequence"
54913,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.085714286,"of, covid-19, with, and, the, in"
54914,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.085714286,"in, the, of, and, with, patients"
54915,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.085714286,"from, of, in, the, and, with"
54916,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.085714286,"to, bats, of"
54917,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.085714286,"of, the, covid-19"
54918,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.085714286,"zoonotic, as, the"
54919,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.085714286,"the, and, three"
54920,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.085714286,"natural, of, three, the, a, to"
54921,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.085714286,"of, the, coronavirus"
54922,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.085714286,"of, in, with"
54923,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.085714286,"of, sequences, in"
54924,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.085714286,"sars-cov-2, a, genome"
54925,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.085714286,"sars-cov-2, zoonotic, host"
54926,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.085714286,"sars-cov-2, animal, in"
54927,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.085714286,"to, sars-cov-2, ace2"
54928,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.085714286,"in, sars-cov-2, ("
54929,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.085714286,"the, that, at"
54930,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.085714286,"disease, is, and"
54931,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.085714286,"infected, wild, the"
54932,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.085714286,"was, identified, in"
54933,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.085714286,"virus, is, bat"
54934,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.085714286,"analysis, suggested, the, of, for, cross-species"
54935,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.085714286,"presence, of, a"
54936,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.085714286,"to, the, of, and, sars-cov, bat"
54937,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.085714286,"are, in, to, of, the, and"
54938,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.085714286,"of, that, the, bat, a, degree"
54939,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.085714286,"the, humans, and"
54940,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.085714286,"and, humans, the"
54941,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.085714286,"pangolins, intermediate, the"
54942,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.085714286,"are, the, to, may, be, of"
54943,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.085714286,"of, the, that, huanan, seafood, market,"
54944,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.085714286,"a, and, that, from, in, bats"
54945,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.085714286,"as, a, in, is, to, sars-cov-2"
54946,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.085714286,"and, in, bats, from, is, to"
54947,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.085714286,"in, a, and, which, to, sars-cov-2"
54948,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.085714286,"the, and, a, of, both, sars-cov-2"
54949,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.085714286,"n, as, et, the, of, and"
54950,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.085714286,"a, the, sars-cov, as, of, and"
54951,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.085714286,"similarity, sars-cov-2, the, that, ace2, of"
54952,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.085714286,"the, that, of, sars-cov-2, both, as"
54953,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.085714286,"the, from, china"
54954,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.085714286,"the, sars-cov-2, pangolins,"
54955,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.085714286,"the, which, a"
54956,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.085714286,"has, the, from"
54957,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.085714286,"the, coronavirus, a"
54958,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.085714286,"to, a, in"
54959,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.085714286,"that, the, to, with, in, of"
54960,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.085714286,"to, and, pangolin"
54961,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.085714286,"to, closely, related"
54962,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.085714286,"are, to, pangolin"
54963,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.085714286,"of, the, patients, in, with, and"
54964,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.085714286,"naturally, occurring, of"
54965,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.085714286,"linked, to, and"
54966,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.085714286,"a, of, the, from, sars-cov-2, in"
54967,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.085714286,"from, in, to, the, of, sars-cov-2"
54968,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.085714286,"that, the, at"
54969,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.085714286,"coronaviruses, of, in"
54970,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.085714286,"of, naturally, occurring"
54971,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.085714286,"of, been, in"
54972,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.085714286,"other, have, been"
54973,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.085714286,"viruses, the, of"
54974,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.085714286,"a, sars-cov-2, from"
54975,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.085714286,"a, by, coronavirus"
54976,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.085714286,"the, to, believe"
54977,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.085714286,"a, the, coronavirus"
54978,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.085714286,"to, the, was"
54979,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.085714286,"the, a, human"
54980,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.085714286,"the, to, than"
54981,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.085714286,"are, all, human"
54982,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.085714286,"zoonotic, virus, in"
54983,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K",0.085714286,"in, with, to"
54984,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.085714286,"been, in, of"
54985,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.085714286,"wild, in, the"
54986,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.085714286,"to, for, the"
54987,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.085714286,"the, of, from, for, as, two, were, a, and"
54988,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.085714286,"of, with, a, and, the, were"
54989,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.085714286,"genome, sars-cov-2, a"
54990,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.085714286,"a, sars-cov-2, genome"
54991,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.085714286,"the, pangolins, intermediate"
54992,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.085714286,"genetic, the, for"
54993,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.085714286,"the, for, cov"
54994,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.085714286,"in, sars-cov-2, the"
54995,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.085714286,"the, of, to, that, have, between, and, animal, sars-cov-2"
54996,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.085714286,"have, the, between, sars-cov-2, and, of, to, that, bat"
54997,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.085714286,"in, found, related, of, covs, pangolin, and, have, to"
54998,"Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.085714286,"coronaviruses, viruses, of"
54999,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.085714286,"of, that, had, the, or, to"
55000,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.085714286,"in, the, that"
55001,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.085714286,"study, of, that, bats, with, coronavirus"
55002,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.085714286,"suggests, that, from, bats, in, the, a, of, transmission"
55003,"a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.085714286,"shared, with, sars-cov-2"
55004,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.085714286,"in, the, of, from, were, and"
55005,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.085714286,"with, sars-cov-2, a"
55006,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.085714286,"sars-cov-2, a, of"
55007,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.085714286,"of, in, that"
55008,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.085714286,"to, virus, the"
55009,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.085714286,"to, from, with"
55010,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.085714286,"the, identity, to"
55011,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.085714286,"sars-cov-2, has, in"
55012,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","bats are also important reservoir species for a great 

range of coronaviruses",0.085714286,"are, coronaviruses, a"
55013,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","bats are also important reservoir species for a great 

range of coronaviruses",0.085714286,"of, a, for"
55014,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.085714286,"in, of, to, the, from, were"
55015,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.085714286,"and, the, of, sars-cov-2, in, from"
55016,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.085714286,"from, bat, the"
55017,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.085714286,"he, of, protein"
55018,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.085714286,"t, that, to"
55019,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.085714286,"is, and, from, to, in, bats"
55020,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.085714286,"similar, to, the, in, bats, and"
55021,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.085714286,"viral, the, for"
55022,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.085714286,"in, the, and, that, may, mice"
55023,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.085714286,"in, the, and, to, that, may"
55024,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.085714286,"may, in, mice, and, that, the"
55025,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.085714286,"that, and, may, to, the, in"
55026,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.085714286,"in, a, to, the, that, was"
55027,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.085714286,"the, beta, sars-cov-2"
55028,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.085714286,"sars-cov-2, to, ace2"
55029,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.085714286,"were, species, and"
55030,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.085714286,"at, the, of, in, raccoon, that"
55031,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.085714286,"in, sequences, of"
55032,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.085714286,"to, in, similarity"
55033,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.085714286,"similarity, to, bat"
55034,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan",0.085714286,"presence, in, of"
55035,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",Wet Market animals maintained in poor conditions,0.085714286,"in, animals, market"
55036,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.085714286,"of, the, from, in, with, and"
55037,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.085714286,"the, are, not"
55038,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.085714286,"the, for, sars-cov-2."
55039,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.085714286,"virus, zoonotic, in"
55040,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.085714286,"most, in, bats"
55041,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.085714286,"diversity, of, the"
55042,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.085714286,"the, sars-cov-2, which"
55043,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.085714286,"progenitor, of, the"
55044,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.085714286,"in, that, the, to, closely, related"
55045,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.085714286,"the, closely, discovered"
55046,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.085714286,"in, the, of, similar, different, species, by, a, and"
55047,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.085714286,"the, and, of, suggesting, a, in, this, between, by"
55048,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.085714286,"of, the, and, viruses, similar, in"
55049,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.085714286,"a, of, with"
55050,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.085714286,"from, to, with"
55051,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.085714286,"sars-cov-2, a, and, to, which, in"
55052,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.085714286,"similar, to, the, in, and, a"
55053,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.085714286,"to, banal, viruses"
55054,"Those who eagerly peddle suggestions of 

laboratory involvement have consistently failed to present 

credible arguments to support their positions.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.085714286,"of, to, their"
55055,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.085714286,"of, similarity, sars-cov-2"
55056,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.085714286,"of, sars-, cov-2"
55057,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.085714286,"the, of, that, by, a, natural"
55058,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.085714286,"is, that, a, of, the, through"
55059,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.085714286,"that, than, the, to, with, of"
55060,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","This suggests that the BANAL series may be able to directly infect  

humans.",0.085714286,"the, banal, to"
55061,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.085714286,"in, to, than"
55062,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.085714286,"banal, viruses, to"
55063,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.085714286,"in, the, more"
55064,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.085714286,"is, in, from"
55065,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.085714286,"the, also, more"
55066,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.085714286,"the, their, of"
55067,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.085714286,"the, three, and"
55068,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.085714286,"for, sars-cov-2, the"
55069,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.085714286,"and, furin, cleavage, site, to, in"
55070,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.085714286,"the, covid-19, virus"
55071,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.085714286,"the, of, its"
55072,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.085714286,"to, the, in, and, these, a"
55073,"with the first case being linked to  

a seafood market","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.085714286,"the, first, case"
55074,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.085714286,"that, with, the"
55075,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.085714286,"the, of, with, a, and, these"
55076,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.085714286,"found, that, with, the, of, suggesting"
55077,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.085714286,"of, on, the, and, with, to"
55078,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.085714286,"in, the, a, was, that, to, humans, at, with"
55079,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.085714286,"the, live, to, in, a, of, with, sars, was, that, virus, animal"
55080,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.085714286,"the, virus, a, that, with, to"
55081,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.085714286,"the, related, to, for, a, wild"
55082,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.085714286,"the, of, and, that, is, animal, was, to, by"
55083,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.085714286,"the, of, coronavirus, is, than, similar, to, animal, for"
55084,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.085714286,"the, of, were, as, a, for, two, from, and"
55085,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.085714286,"of, and, similar, by, different, a, species, in, the"
55086,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.085714286,"that, a, of, into, humans,, the"
55087,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.085714286,"this, the, in, that, likely, for"
55088,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.085714286,"of, the, sequence, virus, and, was"
55089,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.085714286,"the, of, from, and, were, in"
55090,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.085714286,"the, that, in, of, were, to, and, a, an"
55091,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.085714286,"study, found, that, the, of, have, to, as, an"
55092,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.085714286,"a, of, researchers, the, novel, coronavirus, bat, viruses, bats"
55093,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.085714286,"viruses, to, the, whole, genome, in, and, bats, for"
55094,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.085714286,"suggests, that, transmission, of, from, bats, a, in, the"
55095,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.085714286,"bats, as, the, was, to, with, of, for, and"
55096,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.085714286,"that, sars, a, the, virus, was, animal, with, of, in, to, live"
55097,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.085714286,"in, the, of, an, a, that, were, to, and"
55098,"expended to make the simple point 

that COVID-19 had a natural origin.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.085714286,"to, the, that, covid-19, had, a"
55099,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.085714286,"the, and, were, in, with, all, by, of, had, a, to, that"
55100,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.085714286,"the, in, and, to, a, market"
55101,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.085714286,"and, with, the, covid-19, in, of"
55102,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.085714286,"that, the, in, and, to, infected, at, a, market"
55103,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.085714286,"the, of, is, more, than, to, animal, for, be"
55104,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.085714286,"this, of, and, by, suggesting, a, between, in, the"
55105,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.085714286,"of, and, a, which, to, in"
55106,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.085714286,"the, and, of, is, in, human"
55107,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.085714286,"the, of, sars-cov-2, from, for, spillover"
55108,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.085714286,"of, cases, in, the, huanan, by"
55109,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.085714286,"and, that, a, of, the, likely"
55110,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.085714286,"that, study, be, for, sars-cov-2, in"
55111,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.085714286,"that, sars-cov-2, and, a, the, of"
55112,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.085714286,"of, to, the, market, in, that"
55113,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.085714286,"and, to, the, between, that, in"
55114,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Those who eagerly peddle suggestions of 

laboratory involvement have consistently failed to present 

credible arguments to support their positions.",0.085714286,"to, of, their"
55115,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","expended to make the simple point 

that COVID-19 had a natural origin.",0.085714286,"the, that, to, a, covid-19, had"
55116,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","expended to make the simple point 

that COVID-19 had a natural origin.",0.085714286,"the, natural, to"
55117,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","unnatural origin of SARS-CoV-2, but these people are 

simply wrong",0.085714286,"origin, of, these"
55118,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.085714286,"bats, in, china"
55119,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.085714286,"the, we, also"
55120,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.085714286,"we, also, the"
55121,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.085714286,"also, hypothesis, the"
55122,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.",0.085714286,"host, and, the"
55123,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.085714286,"a, in, that, with, the, virus"
55124,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.085714286,"that, sars-cov-2, not"
55125,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.085714286,"a, to, another, not, of, on"
55126,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.085714286,"a, that, the, is, to, of"
55127,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.085714286,"of, sars-cov-2, related"
55128,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.085714286,"of, a, that"
55129,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.085714286,"is, coronavirus, of"
55130,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.085714286,"for, genetic, the"
55131,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.085714286,"show, that, the"
55132,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.085714286,"bat, similarity, to"
55133,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.085714286,"the, bats, is"
55134,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.085714286,"a, the, is, in, that, to"
55135,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.085714286,"that, the, similarity, of, sars-cov-2, ace2"
55136,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.085714286,"the, of, by, natural, a, that"
55137,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.085714286,"and, the, that, of, a, by"
55138,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.085714286,"and, by, the, of, that, a"
55139,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.085714286,"a, the, of, it, that, is"
55140,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.085714286,"the, progenitor, of"
55141,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.085714286,"the, of, is, a, through, that"
55142,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.085714286,"the, of, that, into, humans,, a"
55143,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.085714286,"the, of, in, we, virus, that"
55144,"Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.085714286,"also, the, we"
55145,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.085714286,"a, of, the, and, these, with"
55146,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.085714286,"from, a, and, with, sars-cov-2, the"
55147,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.085714286,"a, coronavirus, the"
55148,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.085714286,"most, coronavirus, the"
55149,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.085714286,"the, of, primary, and, that, in"
55150,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.085714286,"animals, and, to"
55151,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.085714286,"the, which, to, and, wild, animals"
55152,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",The COVID-19 most likely developed from bat origin coronaviruses,0.085714286,"covid-19, the, from"
55153,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.085714286,"the, of, bat, that, a, degree"
55154,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.085714286,"species,, a, of, the, from, species"
55155,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.085714286,"a, from, that, the, is, of"
55156,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.085714286,"of, have, which"
55157,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.085714286,"a, of, on"
55158,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.085714286,"of, a, many"
55159,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.085714286,"humans, zoonotic, animals"
55160,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.085714286,"zoonotic, to, and"
55161,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.085714286,"through, to, zoonotic"
55162,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.085714286,"to, and, animals"
55163,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.085714286,"be, to, that"
55164,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.085714286,"that, to, covs"
55165,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.085714286,"in, that, are"
55166,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",Bats are hosts of many coronaviruses,0.085714286,"of, are, coronaviruses"
55167,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.085714286,"to, most, in"
55168,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.085714286,"however,, to, transmitted"
55169,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.085714286,"the, market, is, in, to, covid-19"
55170,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.085714286,"the, early, of"
55171,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.085714286,"the, which, of"
55172,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.085714286,"the, in, reported"
55173,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.085714286,"that, in, of"
55174,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.085714286,"the, by, of"
55175,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.085714286,"have, which, of"
55176,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.085714286,"the, of, to, and, virus, was"
55177,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.085714286,"the, and, in, bats, similar, to"
55178,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.085714286,"in, a, and, similar, to, the"
55179,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.085714286,"a, to, in, these, the, and"
55180,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.085714286,"of, and, the, in, bats, viruses"
55181,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.085714286,"in, the, found, that, virus, were"
55182,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.085714286,"the, found, be"
55183,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.085714286,"they, that, the"
55184,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.085714286,"in, a, of, have, the, as"
55185,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.085714286,"as, the, of, have, in, a"
55186,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.085714286,"viruses, the, in, bats, of, and"
55187,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.085714286,"to, of, and, from, bat, virus"
55188,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.085714286,"of, to, on, a, another, not"
55189,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.085714286,"a, of, virus, to, and, are"
55190,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.085714286,"to, be, transmission"
55191,Many of these CoVs can infect several animal species as well,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.085714286,"of, these, can, several, species, as"
55192,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.085714286,"to, on, and, or, may, be"
55193,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.085714286,"regions, of, the, in, isolated, a"
55194,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.085714286,"the, to, which, and, wild, animals"
55195,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.085714286,"of, virus, to, the, and, was"
55196,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.085714286,"a, the, was"
55197,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.085714286,"isolated, from, and, sars-cov-2, in, the"
55198,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","t some virus detected in pangolins 

were capable of infecting humans.",0.085714286,"pangolins, in, of"
55199,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","t some virus detected in pangolins 

were capable of infecting humans.",0.085714286,"of, in, were"
55200,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.085714286,"were, at, least, of, from, in, and, to, on"
55201,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.085714286,"the, that, in, of, were, to, by, and, with, a, all, had"
55202,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.085714286,"wild, they, in"
55203,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.085714286,"by, the, in"
55204,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.085714286,"pangolins, their, of"
55205,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.085714286,"a, wild, for, the, to, related"
55206,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.085714286,"the, a, of, to, from, and"
55207,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.085714286,"of, the, a, from, species,, species"
55208,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.085714286,"the, by, has, a, that, such"
55209,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.085714286,"of, the, a, to, that, such"
55210,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.085714286,"the, to, and, showed, identity, sars-cov-2"
55211,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.085714286,"the, from, with, a, and, sars-cov-2"
55212,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.085714286,"the, sars-cov-2, isolated, in, from, and"
55213,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.085714286,"one, with, the, pangolin, to, intermediate"
55214,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.085714286,"on, the, and"
55215,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.085714286,"and, available, the"
55216,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.085714286,"the, is, bats"
55217,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.085714286,"coronaviruses, of, many"
55218,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.085714286,"a, on, of"
55219,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","ARS-CoV-2 is a 

natural virus, not a lab-created one.",0.085714286,"a, is, not"
55220,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.085714286,"the, animal, in"
55221,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.085714286,"are, the, in"
55222,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.085714286,"are, the, not"
55223,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.085714286,"the, most, coronavirus"
55224,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.085714286,"to, intermediate, bat"
55225,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.085714286,"they, in, wild"
55226,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.085714286,"many, other, and"
55227,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.085714286,"have, been, other"
55228,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.085714286,"reservoirs, and, the"
55229,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.085714286,"and, have, that, sars-cov, by, of"
55230,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.085714286,"was, cov, the"
55231,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.085714286,"for, the, cov"
55232,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.085714286,"the, bat, to"
55233,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.085714286,"the, be, found"
55234,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.085714286,"and, the, likely, that, of, a"
55235,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",Genetic evidence suggesting otherwise is yet to be presented.,0.085714286,"to, be, is"
55236,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",Genetic evidence suggesting otherwise is yet to be presented.,0.085714286,"evidence, suggesting, to"
55237,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.085714286,"as, the, or, with, of, for"
55238,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.085714286,"that, the, of, sars-cov-2, both, as"
55239,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.085714286,"a, the, has"
55240,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.085714286,"the, human, a"
55241,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.085714286,"the, by, of, in, and, natural"
55242,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.085714286,"to, has, and"
55243,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.085714286,"nucleotide, and, ratg13"
55244,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.085714286,"was, and, that"
55245,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.085714286,"sars-cov-2, of, than"
55246,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.085714286,"sars-cov-2, of, with"
55247,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.085714286,"sars-cov-2, similarity, of"
55248,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.085714286,"sars-cov-2, bat, of"
55249,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.085714286,"that, as, the"
55250,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.085714286,"the, that, most"
55251,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.085714286,"that, most, the"
55252,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.085714286,"of, the, its"
55253,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.085714286,"nucleotide, ratg13, and"
55254,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.085714286,"the, has, a, that, by, such"
55255,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.085714286,"are, to, be, the, of, may"
55256,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.085714286,"in, the, with, that, to, of"
55257,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.085714286,"for, that, hosts"
55258,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.085714286,"t, that, the"
55259,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.085714286,"also, more, the"
55260,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.085714286,"for, the, virus"
55261,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.085714286,"for, that, the"
55262,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.085714286,"study, of, that, bats, virus, were"
55263,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.085714286,"the, of, market, that, at, in"
55264,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.085714286,"of, that, the, is, a, from"
55265,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.085714286,"a, the, of, and, virus, that"
55266,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.085714286,"a, of, many"
55267,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.085714286,"covs, that, to"
55268,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.085714286,"and, to, the, of, that, a"
55269,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.085714286,"in, obtained, to, of, shows, bat"
55270,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.085714286,"and, of, have, to, related, pangolin, in, found, covs"
55271,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.085714286,"be, that, for, sars-cov-2, in, study"
55272,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.085714286,"a, virus, to, of, and, are"
55273,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.085714286,"by, and, in, the, of, natural"
55274,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.085714286,"in, a, of, novel, coronavirus, that"
55275,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.085714286,"have, the, as"
55276,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.085714286,"sars-cov-2, to, is"
55277,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.085714286,"in, to, the, bats, for, and, whole, genome, viruses"
55278,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.085714286,"in, the, and, that, to, between"
55279,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","�� = 0.01. 

SARS CoV Longquan-140, bat SARS CoV HKU3-1, bat SARS CoV Rp3, 

bat SARS CoV Rs672/2006, bat SARS CoV RsSHC014, bat SARS CoV 

WIV1, bat SARS CoV ZC45 and bat SARS CoV ZXC21 had the same",0.085714286,"the, and, same"
55280,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.085714286,"2, and, viruses, this, the, into"
55281,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.085714286,"with, sars-cov-2, likely"
55282,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.085714286,"of, shows, to, obtained, bat, in"
55283,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.085714286,"for, the, that, in, this, likely"
55284,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.085714286,"that, are, in"
55285,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.085714286,"this, for, the, that, sars-cov-2, in"
55286,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.085714286,"is, than, sars-cov-2"
55287,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.085714286,"of, the, their"
55288,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.085714286,"the, we, find, that, is, same"
55289,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.085714286,"that, the, of, as, sars-cov-2, and"
55290,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.085714286,"that, the, of, sars-cov-2, and, as"
55291,"Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.085714286,"also, the, hypothesis"
55292,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.085714286,"to, show, that"
55293,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.085714286,"pangolin, are, to"
55294,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.085714286,"that, evidence, in"
55295,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.085714286,"the, of, previous"
55296,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.085714286,"and, the, is"
55297,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.085714286,"can, in, and"
55298,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.085714286,"however,, transmitted, to"
55299,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.085714286,"and, major, of"
55300,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.085714286,"in, the, animal"
55301,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.085714286,"that, be, sars-cov-2"
55302,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.085714286,"the, that, they"
55303,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.085714286,"be, a, sars-cov-2"
55304,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.085714286,"a, the, virus"
55305,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.085714286,"a, study, sars-cov-2"
55306,"expended to make the simple point 

that COVID-19 had a natural origin.","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.085714286,"to, the, natural"
55307,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.085714286,"of, a, including"
55308,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.085714286,"in, from, china"
55309,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.085714286,"sars-cov-2, in, ("
55310,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.085714286,"study, sars-cov-2, a"
55311,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.085714286,"of, in, that, novel, coronavirus, a"
55312,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.085714286,"a, and, to, of, which, in"
55313,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.085714286,"the, has, with"
55314,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.085714286,"that, the, of, in, was, to"
55315,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.085714286,"that, the, sars-cov-2, to, in, of"
55316,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.085714286,"a, to, the, natural, of, three"
55317,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.085714286,"the, a, of, that, to, such"
55318,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.085714286,"is, of, coronavirus"
55319,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.085714286,"of, and, viruses, similar, to, in"
55320,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.085714286,"of, the, found, that, with, suggesting"
55321,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.085714286,"to, the, as, of, study, that, have, an, found"
55322,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.085714286,"one, pangolin, with, intermediate, to, the"
55323,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.085714286,"genetic, the, virus, in, and, to"
55324,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.085714286,"s, the, of, similar, to, be"
55325,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.085714286,"of, and, similar, viruses, in, the"
55326,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.085714286,"to, furin, cleavage, site, in, and"
55327,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.085714286,"the, and, to, of, on, with"
55328,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.085714286,"to, and, of, similar, viruses, in"
55329,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.085470085,"in, a, of, to, the, bats, for, coronavirus, and, virus"
55330,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.085470085,"the, on, as, by, with, could, be, were, present, that"
55331,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.085470085,"bat, to, as, animal, the, and, other, small, including, species"
55332,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.085470085,"the, of, study, indicated, that, in, a, sars, and, to"
55333,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.085470085,"be, a, from, to, not, bats, of, and, as, they"
55334,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.085470085,"bats, a, for, coronavirus, the, of, virus, and, in, to"
55335,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.085470085,"the, on, that, could, be, with, were, present, as, by"
55336,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.085470085,"the, first, to, this, it, would, that, in, with, of"
55337,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.085470085,"as, the, animal, to, bat, species, small, and, other, including"
55338,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.085470085,"the, other, by, of, in, and, that, this, than, a"
55339,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.085470085,"to, the, sars, and, a, in, of, study, indicated, that"
55340,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.085470085,"in, the, of, would, to, with, that, this, it, first"
55341,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.085470085,"to, bats, as, they, be, and, not, a, of, from"
55342,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.085470085,"the, and, of, a, that, in, this, than, other, by"
55343,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.085365854,"bats, in, a, large, of, “the, viruses"
55344,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.085365854,"a, of, the, sars-cov-2, and, in, which"
55345,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.085365854,"and, the, of, to, other, into, which"
55346,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.085365854,"a, at, the, and, in, animals, that"
55347,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.085365854,"the, sars-cov-2, and, which, a, of, in"
55348,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.085365854,"as, in, the, of, and, to, laboratory"
55349,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.085365854,"a, the, of, and, in, animals, but"
55350,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.085365854,"from, and, the, of, sars-cov-2, in, a"
55351,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.085365854,"the, of, in, a, to, that, contained"
55352,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.085365854,"the, is, to, that, had, its, animal"
55353,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.085365854,"since, the, that, an, animal, at, of"
55354,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.085365854,"in, to, are, that, was, is, from"
55355,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.085365854,"and, it, that, was, sars-cov-2, in, from"
55356,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.085365854,"the, in, as, to, of, and, laboratory"
55357,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.085365854,"no, such, and, in, to, the, of"
55358,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.085365854,"are, that, was, to, from, is, in"
55359,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.085365854,"as, the, of, first, in, this, to"
55360,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.085365854,"the, that, are, of, is, as, for"
55361,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.085365854,"in, the, a, that, animals, at, and"
55362,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.085365854,"in, the, but, and, a, of, animals"
55363,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.085365854,"a, the, on, of, is, and, it"
55364,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.085365854,"a, of, the, at, that, data, virus"
55365,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.085365854,"we, the, in, do, not, that, of"
55366,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.085365854,"have, by, in, to, the, evidence, of"
55367,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.085365854,"in, of, to, the, first, this, as"
55368,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.085365854,"the, of, and, in, this, as, to"
55369,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.085365854,"its, that, to, the, had, animal, is"
55370,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.085365854,"a, the, of, and, on, it, is"
55371,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.085365854,"and, the, it, for, of, study, a"
55372,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.085365854,"the, of, as, that, and, sequence, later"
55373,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.085365854,"an, to, a, from, animal, virus, zoonotic"
55374,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.085365854,"the, market, that, in, to, and, a"
55375,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.085365854,"of, on, the, and, with, similar, in"
55376,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.085365854,"that, at, the, an, animal, of, since"
55377,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.085365854,"the, that, in, for, of, and, a"
55378,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.085365854,"zoonotic, origin,, virus, human, in, all, previous"
55379,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.085365854,"the, to, these, high, well, of, and"
55380,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.085365854,"the, of, a, to, in, and, virus"
55381,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.085365854,"of, bat, a, with, that, in, virus"
55382,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.085365854,"sars-cov-2, to, a, that, in, and, the"
55383,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.085365854,"were, in, the, at, and, conditions, animal"
55384,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan",0.085365854,"live, in, markets, of, presence, animal, civets,"
55385,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.085365854,"a, of, in, that, the, to, closely"
55386,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.085365854,"other, the, into, which, to, of, and"
55387,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.085365854,"that, a, bat, virus, in, of, with"
55388,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.085365854,"in, contained, the, of, that, a, to"
55389,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.085365854,"the, that, of, natural, genetic, is, for"
55390,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.085365854,"human, virus, zoonotic, in, origin,, all, previous"
55391,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.085365854,"of, the, in, a, to, that, animal"
55392,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.085365854,"as, the, of, and, in, this, to"
55393,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.085365854,"to, in, the, this, that, for, of"
55394,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.085365854,"a, of, the, that, or, to, virus"
55395,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.085365854,"the, that, with, of, or, as, for"
55396,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.085365854,"sequence, that, the, of, later, as, and"
55397,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.085365854,"virus, from, an, animal, to, a, zoonotic"
55398,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.085365854,"“the, of, a, large, viruses, in, bats"
55399,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.085365854,"animal, were, and, in, conditions, at, the"
55400,"Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.085365854,"presence, of, civets,, live, animal, markets, in"
55401,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.085365854,"the, in, and, to, wuhan, seafood, of"
55402,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.085365854,"that, the, a, market, in, to, and"
55403,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.085365854,"to, a, of, in, the, and, with"
55404,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.085365854,"that, it, was, sars-cov-2, from, and, in"
55405,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.085365854,"a, study, for, the, of, and, it"
55406,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.085365854,"sars-cov-2, in, the, this, that, for, of"
55407,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.085365854,"a, of, the, at, by, that, or"
55408,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.085365854,"the, that, of, sars-cov-2, or, it, for"
55409,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.085365854,"for, the, of, that, in, this, to"
55410,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.085365854,"the, that, for, of, sars-cov-2, in, this"
55411,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.085365854,"that, the, of, in, not, we, do"
55412,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.085365854,"and, wuhan, to, the, seafood, in, of"
55413,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.085365854,"in, the, and, that, of, guangdong, are"
55414,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.085365854,"bats, the, these, of, known, as, in"
55415,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.085365854,"these, of, in, bats, the, known, as"
55416,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.085365854,"in, the, of, virus, to, and, a"
55417,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.085365854,"a, at, the, of, data, virus, that"
55418,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.085365854,"the, of, that, virus, a, or, to"
55419,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.085365854,"at, the, that, or, of, a, by"
55420,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.085365854,"of, the, are, that, is, for, as"
55421,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.085365854,"the, of, is, for, natural, that, genetic"
55422,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.085365854,"for, the, of, that, or, with, as"
55423,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.085365854,"the, it, that, or, for, of, sars-cov-2"
55424,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.085365854,"in, the, of, and, to, no, such"
55425,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.085365854,"the, of, in, to, evidence, have, by"
55426,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.085365854,"the, of, to, high, and, well, these"
55427,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.085365854,"the, of, a, which, to, in, and"
55428,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.085365854,"sars-cov-2, of, a, that, in, and, the"
55429,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.085365854,"the, and, in, that, these, bat, are"
55430,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.085365854,"that, are, the, of, and, in, guangdong"
55431,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.085365854,"a, of, in, that, animal, the, to"
55432,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.085365854,"in, these, are, and, bat, that, the"
55433,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.085365854,"on, in, the, of, and, with, similar"
55434,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.085271318,"the, to, in, a, for, of, available, that, virus, and, mammals,"
55435,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.085271318,"as, a, of, the, animal, and, in, with, for, that, intermediate"
55436,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.085271318,"in, a, of, animal, and, that, the, with, as, intermediate, for"
55437,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.085271318,"of, for, mammals,, to, a, virus, available, that, in, and, the"
55438,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.085271318,"had, from, as, and, to, by, the, of, that, in, a"
55439,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.085271318,"the, from, and, in, by, of, had, a, as, to, that"
55440,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.085106383,"that, the, a, or"
55441,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.085106383,"sars-cov-2, related, to, bat"
55442,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.085106383,"other, sars-cov-2, and, a"
55443,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.085106383,"a, in, to, and"
55444,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.085106383,"to, sars-cov-2, bat, and"
55445,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.085106383,"and, in, closely, related"
55446,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.085106383,"the, from, and, wild"
55447,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.085106383,"of, virus, the, and"
55448,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.085106383,"of, are, in, but"
55449,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.085106383,"of, in, a, animal"
55450,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.085106383,"the, in, bats, from"
55451,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.085106383,"in, the, from, as"
55452,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.085106383,"viruses, are, in, the"
55453,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.085106383,"the, viruses, in, horseshoe, sars, bats, as, or"
55454,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.085106383,"the, three, also, of"
55455,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.085106383,"for, and, of, virus"
55456,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.085106383,"for, and, that, of"
55457,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.085106383,"to, bat, such, and"
55458,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.085106383,"bat, in, to, genetic"
55459,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.085106383,"many, and, sequences, in"
55460,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.085106383,"such, sequences, in, coronaviruses"
55461,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.085106383,"in, similar, to, such"
55462,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.085106383,"in, bats, and, to"
55463,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.085106383,"to, and, of, in"
55464,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.085106383,"of, from, bats, identified, and, were, more, than"
55465,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.085106383,"from, and, more, than"
55466,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.085106383,"sequences, and, similar, to"
55467,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.085106383,"in, one, sars-cov-2, to"
55468,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.085106383,"sars-cov-2, to, is, in"
55469,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.085106383,"to, sars-cov-2, in, is"
55470,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.085106383,"to, more, sars-cov-2, than"
55471,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.085106383,"also, in, of, the"
55472,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.085106383,"from, the, may, have"
55473,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.085106383,"the, sars-cov, and, have"
55474,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.085106383,"the, was, in, as"
55475,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.085106383,"that, be, sars-cov-2, by"
55476,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.085106383,"of, sars-cov-2, be, by"
55477,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.085106383,"have, that, been, of"
55478,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.085106383,"be, a, that, sars-cov-2"
55479,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.085106383,"in, the, a, novel, that, to, and, for"
55480,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.085106383,"in, the, without, an, and, a, of, sars-cov-2"
55481,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.085106383,"in, the, of, that, a, sars-cov-2, have, to"
55482,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.085106383,"that, not, an, sars-cov-2, to, cells, and, in"
55483,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.085106383,"to, sars-cov-2, in, the, that, for, ace2, of"
55484,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.085106383,"is, no, that, the"
55485,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.085106383,"in, the, a, was"
55486,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.085106383,"the, with, identical, sars-cov-2"
55487,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.085106383,"the, that, sars-cov-2, research"
55488,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.085106383,"as, virus, natural, and"
55489,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.085106383,"genome, of, virus, and"
55490,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.085106383,"origin, has, been, and"
55491,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.085106383,"the, of, and, a"
55492,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.085106383,"a, and, are, the"
55493,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.085106383,"are, a, the, and"
55494,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.085106383,"of, and, the, viruses"
55495,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.085106383,"the, virus, covid-19, and"
55496,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.085106383,"that, might, the, sars-cov-2"
55497,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.085106383,"of, and, similar, that"
55498,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.085106383,"of, sars-cov-2, and, between"
55499,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.085106383,"in, of, to, the, bat, and, whole, genome"
55500,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.085106383,"bats, the, as, of"
55501,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.085106383,"in, that, the, case"
55502,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.085106383,"a, that, its, the"
55503,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.085106383,"have, and, are, the"
55504,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.085106383,"been, any, and, the"
55505,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.085106383,"the, are, most, and"
55506,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.085106383,"in, the, virus, and"
55507,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.085106383,"as, of, the, in"
55508,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.085106383,"bats, to, hosts, for"
55509,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.085106383,"the, of, to, possibility"
55510,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.085106383,"bats, intermediate, the, from"
55511,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.085106383,"the, from, sars-cov-2, to"
55512,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.085106383,"the, in, had, and"
55513,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.085106383,"has, only, and, the"
55514,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.085106383,"the, as, has, and"
55515,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.085106383,"had, been, and, the"
55516,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.085106383,"the, in, china, and"
55517,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.085106383,"that, the, to, in"
55518,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.085106383,"in, a, to, and"
55519,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.085106383,"linked, to, a, and"
55520,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.085106383,"in, a, were, to"
55521,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.085106383,"sars-cov-2, and, of, the, to, animal, coronavirus, spillover"
55522,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.085106383,"is, an, a, the"
55523,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.085106383,"the, by, that, and"
55524,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.085106383,"and, species, to, the"
55525,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.085106383,"virus, and, as, natural"
55526,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.085106383,"the, cause, as, and"
55527,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.085106383,"to, the, hosts, intermediate"
55528,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.085106383,"with, the, covid-19, of"
55529,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.085106383,"with, the, of, shares"
55530,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.085106383,"to, in, rhinolophus, from"
55531,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.085106383,"the, in, to, wuhan"
55532,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.085106383,"sars-cov-2, the, to, from"
55533,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.085106383,"and, of, to, species"
55534,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.085106383,"of, and, species, the"
55535,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.085106383,"to, and, of, including"
55536,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.085106383,"the, in, was, to"
55537,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.085106383,"in, the, to, and"
55538,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.085106383,"was, from, the, in"
55539,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.085106383,"in, is, of, the"
55540,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.085106383,"the, of, that, sars"
55541,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.085106383,"the, that, of, are"
55542,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.085106383,"natural, of, the, that"
55543,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.085106383,"for, to, a, novel, that, in, and, the"
55544,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.085106383,"the, and, bats, to"
55545,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.085106383,"of, in, the, through"
55546,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.085106383,"pangolins, be, sars-cov-2, in"
55547,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.085106383,"a, in, the, and"
55548,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.085106383,"to, between, bat, and"
55549,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.085106383,"the, that, a, evidence"
55550,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.085106383,"are, the, have, and"
55551,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.085106383,"has, the, only, and"
55552,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.085106383,"studies, genome, the, and"
55553,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.085106383,"from, and, the, of"
55554,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.085106383,"studies, suggest, that, they"
55555,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.085106383,"bat, of, at, the"
55556,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.085106383,"bats, and, pangolins, from"
55557,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.085106383,"from, sars-cov-2, genomes, and"
55558,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.085106383,"to, that, are, this"
55559,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.085106383,"the, animals, sars-cov-2, at"
55560,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.085106383,"of, the, sars-cov-2, from"
55561,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.085106383,"the, sars-cov-2, from, for"
55562,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.085106383,"in, a, to, the, two, more, closely, related"
55563,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.085106383,"in, two, related, to"
55564,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.085106383,"a, the, and, is"
55565,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.085106383,"a, is, in, the"
55566,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.085106383,"the, a, in, this"
55567,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.085106383,"the, at, confirmed, by"
55568,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.085106383,"of, the, lineage, from"
55569,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.085106383,"in, other, and, from"
55570,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.085106383,"the, most, in, and"
55571,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.085106383,"in, the, animal, human"
55572,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.085106383,"the, that, sars-cov-2, at"
55573,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.085106383,"that, sars-cov-2, the, huanan"
55574,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.085106383,"on, sars-cov-2, and, from"
55575,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.085106383,"in, and, on, of"
55576,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.085106383,"of, sars-cov-2, at, in"
55577,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.085106383,"to, of, from, zoonotic"
55578,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.085106383,"the, more, of, and"
55579,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.085106383,"sars-cov-2, of, a, in, an, and, without, the"
55580,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.085106383,"a, of, animals,, including"
55581,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.085106383,"one, to, sars-cov-2, in"
55582,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.085106383,"sars-cov-2, of, to, a, have, that, in, the"
55583,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.085106383,"this, of, to, the, that, had, been, it."
55584,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.085106383,"if, humans, it, is, that, the, when, first"
55585,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.085106383,"sars-cov-2, cells, to, that, not, in, an, and"
55586,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.085106383,"in, that, a, sars-cov-2"
55587,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.085106383,"a, wiv, that, or"
55588,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.085106383,"the, of, most, closely, related, to, by, is"
55589,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.085106383,"at, to, in, the, or, by, across, similarly,, sars, of, and, bats,"
55590,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.085106383,"that, the, of, sars-cov-2, and, coronavirus, more, viruses"
55591,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.085106383,"be, that, sars-cov-2, by"
55592,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.085106383,"the, sars-cov-2, animals, at"
55593,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.085106383,"at, the, confirmed, by"
55594,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.085106383,"the, were, that, animals"
55595,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.085106383,"the, could, be, sars-cov-2"
55596,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.085106383,"the, to, as, genetic"
55597,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.085106383,"a, genome, the, in"
55598,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.085106383,"of, a, to, other, the, market, were, in"
55599,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.085106383,"has, the, as, and"
55600,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.085106383,"to, the, that, virus"
55601,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.085106383,"the, to, that, virus"
55602,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.085106383,"of, coronaviruses, a, and"
55603,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.085106383,"to, have, that, of"
55604,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.085106383,"that, of, have, to"
55605,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.085106383,"other, and, in, from"
55606,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.085106383,"and, cov, that, in"
55607,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.085106383,"from, in, origin, and"
55608,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.085106383,"in, that, cov, which"
55609,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.085106383,"the, of, and, horseshoe"
55610,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.085106383,"to, and, from, human"
55611,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.085106383,"to, coronavirus, from, and"
55612,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.085106383,"animals, to, is, and"
55613,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.085106383,"to, of, the, was"
55614,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.085106383,"of, to, the, intermediate"
55615,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.085106383,"a, of, the, around"
55616,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.085106383,"that, to, this, it., the, had, of, been"
55617,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.085106383,"the, virus, that, to"
55618,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.085106383,"the, through, in, of"
55619,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.085106383,"an, to, from, the, virus, of, and, horseshoe"
55620,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.085106383,"a, sars-cov-2, using, the"
55621,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Bats have been reported as being the rich source of 

coronaviruses",0.085106383,"bats, the, of, have"
55622,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Bats have been reported as being the rich source of 

coronaviruses",0.085106383,"the, been, as, of"
55623,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.085106383,"sars-cov-2, from, a, the"
55624,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.085106383,"the, with, have, a"
55625,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.085106383,"sars-cov-2, a, the, from"
55626,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.085106383,"the, of, sars-cov-2, circulating"
55627,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.085106383,"to, between, and, bat"
55628,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.085106383,"an, the, was, on, and, of, to, by"
55629,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.085106383,"and, from, the, virus"
55630,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.085106383,"to, the, virus, bats"
55631,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.085106383,"that, a, virus, in"
55632,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.085106383,"that, a, to, through"
55633,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.085106383,"is, and, animals, to"
55634,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.085106383,"the, of, has, to"
55635,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.085106383,"of, the, is, naturally"
55636,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.085106383,"the, to, humans, and"
55637,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.085106383,"the, believe, that, more"
55638,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.085106383,"animal, to, and, in"
55639,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.085106383,"initial, the, and, was"
55640,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.085106383,"natural, and, is, or"
55641,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.085106383,"to, be, the, reservoir"
55642,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.085106383,"the, to, be, natural"
55643,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.085106383,"it, is, of, a"
55644,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.085106383,"the, bats, natural, of"
55645,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.085106383,"have, the, may, from"
55646,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.085106383,"may, have, been, the"
55647,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.085106383,"on, the, of, and, an, was, to, by"
55648,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.085106383,"in, the, also, and"
55649,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.085106383,"the, bat, that, to"
55650,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.085106383,"the, reservoir, is, to"
55651,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.085106383,"virus, the, was, in"
55652,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.085106383,"a, the, have, with"
55653,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.085106383,"the, was, animals, a"
55654,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.085106383,"the, with, a, coronavirus"
55655,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.085106383,"the, of, bat, viruses, a, bats, with, that"
55656,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.085106383,"however,, a, of, genomic"
55657,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.085106383,"the, of, with, be"
55658,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.085106383,"that, the, with, bat"
55659,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.085106383,"to, of, the, has"
55660,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.085106383,"the, that, same, receptor"
55661,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.085106383,"the, also, that, for"
55662,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.085106383,"it, that, the, and"
55663,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.085106383,"to, and, intermediate, hosts"
55664,"the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.085106383,"the, later, that, sars-cov-2"
55665,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.085106383,"of, that, the, from"
55666,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.085106383,"are, coronaviruses, the, bat"
55667,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.085106383,"the, genome, that, virus"
55668,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.085106383,"to, sars-cov-2, that, spike"
55669,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.085106383,"viruses, from, of, the"
55670,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.085106383,"a, in, the, from"
55671,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.085106383,"bat, by, genetic, is"
55672,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.085106383,"the, to, is, a"
55673,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.085106383,"of, the, is, from"
55674,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.085106383,"to, of, in, bats"
55675,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.085106383,"have, genetic, in, bat"
55676,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.085106383,"that, bat, in, genetic"
55677,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.085106383,"been, the, in, and"
55678,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.085106383,"to, and, have, the"
55679,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.085106383,"in, the, and, infected"
55680,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.085106383,"and, natural, is, or"
55681,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.085106383,"and, evidence, that, or"
55682,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.085106383,"the, that, from, and"
55683,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.085106383,"that, and, the, sars-cov-2"
55684,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.085106383,"to, sars-cov-2, by, of"
55685,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.085106383,"close, to, transmission, be"
55686,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.085106383,"of, the, coronavirus, that"
55687,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.085106383,"to, the, and, that"
55688,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.085106383,"the, other, genome, and"
55689,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.085106383,"bat, of, genome, the"
55690,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.085106383,"the, of, and, coronavirus"
55691,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.085106383,"the, of, virus, with"
55692,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.085106383,"in, the, virus, was"
55693,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.085106383,"virus, in, of, with"
55694,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.085106383,"virus, genome, and, of"
55695,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.085106383,"the, of, showed, with"
55696,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.085106383,"to, the, reservoir, be"
55697,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.085106383,"as, cause, and, the"
55698,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.085106383,"the, and, as, well"
55699,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.085106383,"such, and, in, the"
55700,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.085106383,"the, zoonotic, to, and"
55701,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.085106383,"the, and, coronaviruses, that"
55702,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.085106383,"of, and, with, human"
55703,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.085106383,"of, and, four, for"
55704,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.085106383,"sequence, sars-cov-2, the, of"
55705,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.085106383,"the, of, to, genomic"
55706,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.085106383,"the, of, that, similar, to, indicated, coronavirus, is"
55707,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.085106383,"of, human, and, with"
55708,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.085106383,"and, the, of, has"
55709,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.085106383,"bat, and, the, with"
55710,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.085106383,"of, with, novel, coronavirus"
55711,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.085106383,"such, bat, to, and"
55712,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.085106383,"the, that, related, to"
55713,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.085106383,"that, the, more, of"
55714,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.085106383,"and, sars-cov-2, a, other"
55715,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.085106383,"sars-cov-2, from, and, on"
55716,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.085106383,"the, genome, and, other"
55717,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.085106383,"the, and, a, natural"
55718,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.085106383,"the, natural, and, not"
55719,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.085106383,"in, to, sars-cov-2, human"
55720,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.085106383,"and, at, the, is"
55721,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.085106383,"the, bat, between, and"
55722,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.085106383,"the, is, at, that"
55723,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.085106383,"virus, the, covid-19, and"
55724,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.085106383,"two, of, the, and"
55725,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.085106383,"the, that, in, animals"
55726,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.085106383,"the, and, which, is"
55727,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.085106383,"was, isolated, in, a"
55728,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.085106383,"in, were, seafood, market"
55729,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.085106383,"that, a, sars-cov-2, is"
55730,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.085106383,"a, of, the, presence, two, novel, and, genome"
55731,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.085106383,"the, that, a, novel"
55732,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.085106383,"two, of, genome, and"
55733,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.085106383,"intermediate, hosts, to, the"
55734,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.085106383,"initial, to, the, of"
55735,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.085106383,"of, to, be, may"
55736,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.085106383,"the, sars-cov-2, huanan, that"
55737,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.085106383,"from, the, which, sars-cov-2"
55738,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.085106383,"the, for, of, which"
55739,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.085106383,"of, samples, from, sars-cov-2"
55740,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Bats are natural hosts of many of the known  

coronaviruses",0.085106383,"the, coronaviruses, are, of"
55741,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.085106383,"be, intermediate, to, the"
55742,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.085106383,"sars-cov-2, from, the, which"
55743,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.085106383,"sars-cov-2, has, similarity, the"
55744,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.085106383,"with, the, of, a, to, that, in, at"
55745,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.085106383,"in, to, the, of"
55746,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.085106383,"the, that, these, of"
55747,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.085106383,"sars-cov-2, of, the, with"
55748,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.085106383,"the, of, that, could"
55749,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.085106383,"the, huanan, to, covid-19, in, is, at, market"
55750,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.085106383,"the, to, in, a, of, horseshoe, was, yunnan"
55751,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.085106383,"in, closely, related, sars-cov-2"
55752,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.085106383,"closely, related, in, sars-cov-2"
55753,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.085106383,"of, in, and, on"
55754,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.085106383,"the, and, even, of"
55755,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.085106383,"in, lineages, of, have"
55756,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.085106383,"for, the, natural, of"
55757,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.085106383,"in, the, of, for"
55758,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.085106383,"of, the, has, been"
55759,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.085106383,"similar, of, sars-cov-2, ratg13"
55760,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.085106383,"a, the, was, to"
55761,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.085106383,"was, the, animals, a"
55762,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.085106383,"a, to, than, the"
55763,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.085106383,"of, the, genomic, to"
55764,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.085106383,"the, of, a, around"
55765,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.085106383,"a, virus, found, the"
55766,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.085106383,"china, the, of, virus"
55767,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.085106383,"the, of, new, virus"
55768,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.085106383,"of, the, bat, a"
55769,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.085106383,"to, bats, hosts, for"
55770,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.085106383,"are, to, that, this"
55771,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.085106383,"to, that, this, also"
55772,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.085106383,"the, of, shares, with"
55773,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.085106383,"a, genome, of, with"
55774,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.085106383,"a, natural, and, host"
55775,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.085106383,"cov, the, sars-cov-2, with"
55776,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.085106383,"sars-cov-2, to, spillover, of, animal, coronavirus, and, the"
55777,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.085106383,"and, the, of, bat, to, sars-related, related, with, that, in, for, events"
55778,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.085106383,"to, a, the, location"
55779,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.085106383,"because, bat, to, the"
55780,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.085106383,"viruses, to, the, is"
55781,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.085106383,"the, been, and, any"
55782,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.085106383,"been, the, and, had"
55783,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.085106383,"sars-cov-2, virus, to, the"
55784,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.085106383,"genome, the, virus, and"
55785,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.085106383,"the, to, sars-cov-2, virus"
55786,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.085106383,"the, that, to, related"
55787,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.085106383,"that, virus, in, a"
55788,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.085106383,"virus, with, in, of"
55789,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.085106383,"with, of, a, genome"
55790,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.085106383,"of, bat, a, in"
55791,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.085106383,"a, virus, that, with, bat, in, of, yunnan"
55792,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.085106383,"of, that, in, bat"
55793,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.085106383,"that, the, later, sars-cov-2"
55794,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.085106383,"the, human, with, market"
55795,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.085106383,"a, the, that, animal"
55796,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.085106383,"that, the, of, host"
55797,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.085106383,"the, as, from, in"
55798,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.085106383,"the, and, also, in"
55799,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.085106383,"the, as, sars-cov-2, in"
55800,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.085106383,"the, sars-cov-2, cluster, and"
55801,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.085106383,"the, of, humans, an"
55802,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.085106383,"the, from, with, and"
55803,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.085106383,"the, sars-cov-2, has, of"
55804,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.085106383,"which, sars-cov-2, at, the"
55805,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.085106383,"the, amino, acid, sequence"
55806,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.085106383,"to, therefore, that, be"
55807,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.085106383,"the, in, to, a"
55808,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.085106383,"a, to, the, for"
55809,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.085106383,"ratg13, to, the, in"
55810,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.085106383,"in, the, sars-cov-2, as"
55811,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.085106383,"in, with, sars-cov-2, the"
55812,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.085106383,"for, and, with, the, in, of, a, animal"
55813,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.085106383,"the, that, in, for, of, and, with, a"
55814,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.085106383,"the, for, transmission, and"
55815,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.085106383,"that, may, have, in"
55816,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.085106383,"to, a, was, in"
55817,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.085106383,"be, of, sars-cov-2, by"
55818,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.085106383,"the, for, of, infect"
55819,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.085106383,"the, of, ability, and"
55820,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.085106383,"be, the, for, sars-cov-2"
55821,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.085106383,"to, the, possibility, of"
55822,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.085106383,"to, the, were, several, susceptible, and, in, species"
55823,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.085106383,"intermediate, the, from, in"
55824,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.085106383,"that, the, sars-cov-2, for"
55825,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.085106383,"in, of, the, samples, from, positive, for, presence"
55826,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.085106383,"from, in, the, that"
55827,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.085106383,"of, the, which, for"
55828,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.085106383,"the, of, for, infect"
55829,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.085106383,"the, of, host, sars-cov-2."
55830,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.085106383,"the, sars-cov-2, natural, a"
55831,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.085106383,"to, a, in, the, virus, or, zoonotic, of"
55832,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.085106383,"more, of, the, and"
55833,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Bats are the second  

largest order of mammals, with over 1,230 species.",0.085106383,"bats, the, with, of"
55834,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.085106383,"the, including, of, sars-cov-2"
55835,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.085106383,"belongs, the, of, sars-cov-2"
55836,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.085106383,"the, animal, and, of"
55837,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.085106383,"the, of, as, for"
55838,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.085106383,"and, sars-cov-2, to, bat"
55839,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.085106383,"are, the, most, and"
55840,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.085106383,"and, in, most, the"
55841,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.085106383,"sars-cov-2, including, and, coronaviruses"
55842,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.085106383,"the, in, china, were"
55843,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.085106383,"and, the, in, viruses"
55844,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.085106383,"to, the, an, and"
55845,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.085106383,"the, are, viruses, in"
55846,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.085106383,"a, bat, in, of"
55847,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.085106383,"of, the, and, same"
55848,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.085106383,"in, bat, genetic, to"
55849,hese close genetic relations suggest that they all have their ecological origin in bat populations,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.085106383,"genetic, that, in, bat"
55850,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.085106383,"a, of, the, with, bat, viruses, that, bats"
55851,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.085106383,"and, of, the, to, related, in, with, that, bat, for, sars-related, events"
55852,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.085106383,"a, and, to, specific, of, which, in, the"
55853,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.085106383,"sars-cov-2, a, with, to"
55854,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.085106383,"of, to, sars-cov-2, which"
55855,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.085106383,"genetic, is, by, bat"
55856,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.085106383,"at, the, which, sars-cov-2"
55857,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.085106383,"the, also, of, three"
55858,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.085106383,"of, sars-cov-2, to, by"
55859,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.085106383,"to, the, sars-cov-2, also"
55860,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.085106383,"the, by, to, of"
55861,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.085106383,"to, of, viruses, related"
55862,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.085106383,"and, that, similar, of"
55863,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.085106383,"the, rbd, that, of"
55864,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.085106383,"have, to, the, of"
55865,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.085106383,"of, to, with, that"
55866,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.085106383,"viruses, to, in, that"
55867,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.085106383,"the, of, spike, is"
55868,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.085106383,"sars-cov-, 2, of, the"
55869,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.085106383,"the, have, to, and"
55870,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.085106383,"to, the, location, a"
55871,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.085106383,"is, the, viruses, to"
55872,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.085106383,"of, four, and, for"
55873,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.085106383,"the, to, closely, related, most, is, by, of"
55874,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.085106383,"genetic, the, as, to"
55875,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.085106383,"the, of, is, virus"
55876,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.085106383,"bats, as, was, and"
55877,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.085106383,"the, virus, covid-19, to"
55878,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.085106383,"virus, to, the, sars-cov-2"
55879,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.085106383,"the, coronaviruses, are, bat"
55880,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.085106383,"in, the, case, that"
55881,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.085106383,"that, it, when, first, the, if, humans, is"
55882,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.085106383,"the, in, infected, and"
55883,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.085106383,"and, that, the, covid-19"
55884,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.085106383,"the, it, is, that"
55885,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.085106383,"to, the, of, zoonotic, occurred, a, virus, with"
55886,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.085106383,"in, with, the, by, to, that, of, guangdong"
55887,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.085106383,"of, the, indicated, that, coronavirus, is, similar, to"
55888,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.085106383,"several, species, susceptible, to, were, and, in, the"
55889,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.085106383,"the, sars, as, viruses, in, or, horseshoe, bats"
55890,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.085106383,"more, than, were, identified, from, bats, of, and"
55891,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.085106383,"the, and, to, bat, in, of, whole, genome"
55892,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.085106383,"in, a, related, the, two, more, closely, to"
55893,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.085106383,"a, of, the, genome, presence, and, two, novel"
55894,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.085106383,"positive, samples, from, the, presence, of, in, for"
55895,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.085106383,"a, of, viruses, in, and, to, which, the"
55896,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.085106383,"the, whole, genome, bats, more, for, virus, than"
55897,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.085106383,"that, a, bat, virus, in, yunnan, of, with"
55898,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.085106383,"that, the, for, as, similar, to, a, bat"
55899,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.085106383,"the, to, sars, in, by, across, of, or, bats,, and, similarly,, at"
55900,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.085106383,"the, virus, an, to, of, and, from, horseshoe"
55901,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.085106383,"the, of, zoonotic, or, to, a, virus, in"
55902,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.085106383,"the, of, at, a, virus, in, animal, for"
55903,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.085106383,"the, to, was, in, of, a, horseshoe, yunnan"
55904,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.085106383,"one, of, to, a, was, in, yunnan, province"
55905,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.085106383,"in, a, of, animal, and, the, with, for"
55906,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.085106383,"in, a, of, and, that, the, with, for"
55907,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.085106383,"the, of, market, in, to, were, a, other"
55908,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.085106383,"a, in, the, with, that, to, of, at"
55909,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.085106383,"covid-19, is, to, at, the, huanan, market, in"
55910,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.085106383,"and, the, of, to, specific, a, in, which"
55911,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.085106383,"a, at, the, in"
55912,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.085106383,"to, the, zoonotic, a"
55913,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.085106383,"in, many, sequences, and"
55914,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.085106383,"the, market, with, human"
55915,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.085106383,"the, that, its, a"
55916,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.085106383,"a, virus, the, found"
55917,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.085106383,"to, a, with, sars-cov-2"
55918,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.085106383,"and, coronaviruses, that, to"
55919,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.085106383,"that, in, to, from"
55920,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.085106383,"to, that, and, from"
55921,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.085106383,"sars-cov-2, to, related, in"
55922,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.085106383,"and, in, that, to"
55923,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.085106383,"the, also, lab, leak"
55924,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.085106383,"the, also, as, hypothesis"
55925,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.085106383,"in, a, of, to, the, which, and, viruses"
55926,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.085106383,"in, and, humans, a"
55927,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.085106383,"a, natural, host, and"
55928,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.085106383,"the, in, that, virus"
55929,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.085106383,"in, the, bat, virus"
55930,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.085106383,"is, the, of, spike"
55931,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.085106383,"of, that, a, sars-cov-2"
55932,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.085106383,"a, of, is, it"
55933,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.085106383,"of, a, coronavirus, that"
55934,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.085106383,"sars-cov-2, that, is, of"
55935,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.085106383,"the, virus, that, from"
55936,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.085106383,"is, the, virus, genetic"
55937,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.085106383,"the, is, that, not"
55938,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.085106383,"that, the, is, from"
55939,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.085106383,"it, is, that, the"
55940,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.085106383,"is, a, the, in"
55941,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.085106383,"from, the, that, in"
55942,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.085106383,"sars-cov-2, of, for, to, ace2, that, in, the"
55943,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.085106383,"all, that, to, in"
55944,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.085106383,"of, shows, a, which"
55945,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.085106383,"also, to, that, this"
55946,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.085106383,"an, pangolins, the, in"
55947,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.085106383,"of, to, was, in"
55948,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.085106383,"sars-cov-2, with, identical, the"
55949,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.085106383,"coronaviruses, a, of, and"
55950,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.085106383,"or, pangolins, the, sars-cov-2"
55951,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.085106383,"coronaviruses, the, that, and"
55952,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.085106383,"that, the, rbd, of"
55953,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.085106383,"the, is, all, in"
55954,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.085106383,"the, initial, was, and"
55955,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.",0.085106383,"of, bats., the, in"
55956,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.085106383,"evidence, the, that, a"
55957,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.085106383,"this, a, the, in"
55958,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.085106383,"a, the, that, novel"
55959,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.085106383,"in, the, originated, a"
55960,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.085106383,"and, from, wild, the"
55961,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.085106383,"the, to, that, animals"
55962,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.085106383,"covid-19, the, that, from"
55963,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.085106383,"evidence, that, the, to"
55964,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.085106383,"the, of, is, from"
55965,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.085106383,"that, the, same, receptor"
55966,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.085106383,"the, of, sequence, that"
55967,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.085106383,"the, to, in, wuhan"
55968,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.085106383,"to, originated, in, the"
55969,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.085106383,"animals,, including, a, of"
55970,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.085106383,"in, and, are, to"
55971,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.085106383,"are, to, in, and"
55972,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.085106383,"are, that, to, in"
55973,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.085106383,"to, in, all, that"
55974,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.085106383,"of, which, in, the"
55975,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.085106383,"which, the, in, by"
55976,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.085106383,"that, the, animals, in"
55977,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.085106383,"that, the, virus, in"
55978,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.085106383,"that, the, with, virus"
55979,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.085106383,"the, in, market, china"
55980,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.085106383,"that, of, have, been"
55981,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.085106383,"the, that, to, animals"
55982,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.085106383,"of, the, known, in"
55983,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.085106383,"of, that, the, or"
55984,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.085106383,"is, that, no, the"
55985,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.085106383,"that, the, or, of"
55986,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.085106383,"all, the, in, is"
55987,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.085106383,"by, in, the, is"
55988,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.085106383,"is, the, by, from"
55989,"In fact, a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.085106383,"in, the, of, bats."
55990,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.085106383,"bats, between, and, the"
55991,"S1/S2 cleavage sites of coronaviruses are frequently modi- 

fied by insertions or deletions (indels) during evolution","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.085106383,"sites, of, or, during"
55992,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.085106383,"of, with, and, to"
55993,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.085106383,"and, the, bats, between"
55994,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.085106383,"and, closely, related, in"
55995,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.085106383,"close, transmission, to, be"
55996,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.085106383,"to, the, of, bats, and, may, as, are"
55997,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.085106383,"was, a, the, in"
55998,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.085106383,"of, lineage, the, from"
55999,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.085106383,"is, the, sars-cov-2, similar"
56000,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.085106383,"in, the, virus, of"
56001,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.085106383,"the, from, bats, intermediate"
56002,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.085106383,"and, from, bats, pangolins"
56003,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.085106383,"the, in, from, intermediate"
56004,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.085106383,"the, in, pangolins, an"
56005,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.085106383,"the, between, and, (or"
56006,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.085106383,"the, is, to, which"
56007,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.085106383,"a, bat, sars-cov-2, genome"
56008,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.085106383,"of, humans, an, is"
56009,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.085106383,"of, and, for, virus"
56010,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.085106383,"a, of, however,, genomic"
56011,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.085106383,"that, wiv, or, a"
56012,"Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.085106383,"also, the, lab, leak"
56013,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.085106383,"in, the, not, with"
56014,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.085106383,"the, in, most, by"
56015,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.085106383,"in, to, sars-cov-2, that"
56016,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.085106383,"through, that, to, a"
56017,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.085106383,"of, could, the, that"
56018,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.085106383,"an, of, the, humans"
56019,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.085106383,"is, an, of, humans"
56020,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.085106383,"that, could, an, with"
56021,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.085106383,"sars-cov-2, humans, in, to"
56022,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.085106383,"to, sars-cov-2, that, as"
56023,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.085106383,"he, sars-cov-2, the, of"
56024,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.085106383,"have, the, and, sars-cov"
56025,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","S1/S2 cleavage sites of coronaviruses are frequently modi- 

fied by insertions or deletions (indels) during evolution",0.085106383,"or, of, during, sites"
56026,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.085106383,"the, from, an, appears"
56027,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.085106383,"cov, bat, the, sars-cov-2"
56028,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.085106383,"as, the, for, of"
56029,"Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.085106383,"also, the, hypothesis, as"
56030,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.085106383,"the, ability, of, and"
56031,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.085106383,"of, the, origin, and"
56032,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.085106383,"has, the, origin, of"
56033,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.085106383,"the, such, in, and"
56034,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.085106383,"to, the, initial, of"
56035,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.085106383,"have, the, of, to"
56036,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.085106383,"the, is, by, in"
56037,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.085106383,"is, a, an, the"
56038,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.085106383,"the, a, from, is"
56039,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.085106383,"the, in, which, by"
56040,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.085106383,"has, to, identity, and"
56041,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.085106383,"that, and, sars-cov-2, to"
56042,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.085106383,"and, to, be, the"
56043,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.085106383,"and, has, been, origin"
56044,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.085106383,"and, to, an, the"
56045,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.085106383,"the, is, by, from"
56046,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.085106383,"from, an, the, appears"
56047,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.085106383,"to, the, natural, be"
56048,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.085106383,"of, be, the, with"
56049,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.085106383,"sars-cov-2, and, of, bat"
56050,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.085106383,"of, sars-cov-2, ratg13, similar"
56051,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.085106383,"of, sequences, and, similar"
56052,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.085106383,"sars-cov, from, and, sars-cov-2"
56053,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.085106383,"in, of, which, to"
56054,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.085106383,"in, such, coronaviruses, sequences"
56055,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.085106383,"the, that, sars-cov-2, might"
56056,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.085106383,"the, sars-cov-2, be, for"
56057,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.085106383,"the, pangolins, sars-cov-2, or"
56058,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.085106383,"sars-cov-2, and, genomes, from"
56059,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.085106383,"that, the, also, for"
56060,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.085106383,"the, genome, virus, that"
56061,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.085106383,"the, bats, for, whole, genome, more, than, virus"
56062,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.085106383,"the, that, virus, covid-19"
56063,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.085106383,"are, to, the, a"
56064,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.085106383,"the, for, to, a, that, similar, bat, as"
56065,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.085106383,"bat, to, which, the"
56066,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.085106383,"the, bat, at, of"
56067,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.085106383,"at, of, sars-cov-2, in"
56068,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.085106383,"the, in, a, genome"
56069,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.085106383,"sars-cov-2, a, using, the"
56070,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.085106383,"of, the, genome, bat"
56071,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.085106383,"the, of, a, origin"
56072,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.085106383,"at, a, in, the"
56073,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.085106383,"genome, bat, sars-cov-2, a"
56074,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.085106383,"sars-cov-2, in, the, bat"
56075,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.085106383,"in, from, of, to"
56076,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.085106383,"a, was, to, in"
56077,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.085106383,"to, in, a, of, one, was, yunnan, province"
56078,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.085106383,"of, which, shows, a"
56079,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.085106383,"in, of, to, was"
56080,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.085106383,"of, in, sequences, a"
56081,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.085106383,"and, sequences, similar, to"
56082,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.085106383,"in, related, two, to"
56083,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.085106383,"of, genome, and, two"
56084,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.085106383,"have, in, lineages, of"
56085,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.085106383,"to, in, and, of"
56086,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.085106383,"similar, sequences, of, and"
56087,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.085106383,"sars-cov-2, pangolins, in, be"
56088,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.085106383,"with, that, could, an"
56089,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.085106383,"the, may, have, been"
56090,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.085106383,"sars-cov-, 2, the, of"
56091,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.085106383,"the, sars-cov-2, have, to"
56092,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.085106383,"the, been, have, to"
56093,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.085106383,"of, sequences, a, in"
56094,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.085106383,"sars-cov-2, to, is, bat"
56095,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.085106383,"to, be, and, the"
56096,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.085106383,"evidence, that, and, or"
56097,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.085106383,"the, more, believe, that"
56098,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.085106383,"the, is, more, than"
56099,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.085106383,"the, viruses, that, more, coronavirus, of, and, sars-cov-2"
56100,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.085106383,"cov, that, in, and"
56101,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.085106383,"to, the, because, bat"
56102,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.085106383,"the, to, is, bat"
56103,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.085106383,"the, originated, in, to"
56104,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.085106383,"bat, sars-cov-2, the, in"
56105,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.085106383,"of, in, guangdong, that, with, by, the, to"
56106,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.085106383,"between, (or, and, the"
56107,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.085106383,"the, with, bat, that"
56108,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.085106383,"the, of, that, more"
56109,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.085106383,"sequences, and, of, pangolin"
56110,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.085106383,"and, this, the, of"
56111,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.085106383,"in, that, may, have"
56112,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.085106383,"more, than, to, sars-cov-2"
56113,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.085106383,"the, of, sars-cov-2, belongs"
56114,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.085106383,"bats, the, of, are, to, as, and, may"
56115,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.085106383,"the, genome, of, bat"
56116,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.085106383,"the, in, virus, and"
56117,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.085106383,"studies, and, the, genome"
56118,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.085106383,"origin, in, and, from"
56119,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.085106383,"the, between, and, bat"
56120,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.085106383,"of, virus, the, china"
56121,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.085106383,"virus, and, genome, the"
56122,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.085106383,"virus, the, in, bat"
56123,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.085106383,"with, and, to, sars-cov-2"
56124,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.085106383,"to, with, sars-cov-2, and"
56125,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.085106383,"and, similarity, sars-cov-2, to"
56126,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.085106383,"to, with, of, and"
56127,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.085106383,"with, and, sars-cov-2, the"
56128,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.085106383,"with, sars-cov-2, the, and"
56129,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.085106383,"of, the, with, showed"
56130,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.085106383,"by, the, of, sars-cov-2"
56131,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.085106383,"and, for, transmission, the"
56132,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.085106383,"of, and, that, for"
56133,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.085106383,"in, of, the, and"
56134,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.085106383,"from, a, in, the"
56135,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.085106383,"the, a, in, originated"
56136,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.085106383,"from, cov, and, bats,"
56137,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.085106383,"more, than, from, and"
56138,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.085106383,"sars-cov-2, and, sars-cov, from"
56139,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.085106383,"cov, from, bats,, and"
56140,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.085106383,"the, for, with, and"
56141,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.085106383,"the, for, virus, that, this, and, in, of"
56142,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.085106383,"virus, in, the, of"
56143,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.085106383,"in, the, that, it"
56144,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.085106383,"the, that, in, this"
56145,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.085106383,"cov, that, in, which"
56146,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.085106383,"the, to, which, is"
56147,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.085106383,"the, virus, bats, to"
56148,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.085106383,"the, has, similarity, sars-cov-2"
56149,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.085106383,"the, of, origin, has"
56150,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.085106383,"of, rbd, pangolin-cov, with"
56151,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.085106383,"zoonotic, of, from, to"
56152,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.085106383,"of, the, virus, with"
56153,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.085106383,"a, zoonotic, the, virus, with, of, occurred, to"
56154,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.085106383,"of, pangolin-cov, with, rbd"
56155,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.085106383,"as, the, in, was"
56156,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.085106383,"that, was, the, in"
56157,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.085106383,"in, the, for, that"
56158,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.085106383,"to, sars-cov-2, that, is"
56159,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.085106383,"of, be, the, bat"
56160,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.085106383,"sars-cov-2, a, the, virus"
56161,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.085106383,"a, and, sars-cov-2, the"
56162,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.085106383,"a, sars-cov-2, the, and"
56163,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.085106383,"circulating, the, of, sars-cov-2"
56164,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.085106383,"at, a, animal, in, for, the, virus, of"
56165,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.085106383,"the, for, sars-cov-2, from"
56166,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.085106383,"human, in, the, animal"
56167,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.085106383,"the, that, animal, a"
56168,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.085106383,"the, from, that, covid-19"
56169,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.085106383,"covid-19, that, the, for"
56170,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.085106383,"a, from, in, sars-cov-2"
56171,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.085106383,"is, to, the, reservoir"
56172,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.085106383,"of, sars-cov-2, samples, from"
56173,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.085106383,"a, in, sars-cov-2, from"
56174,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.085106383,"and, are, the, a"
56175,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.085106383,"the, a, for, and"
56176,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.085106383,"and, are, a, the"
56177,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.085106383,"were, to, a, in"
56178,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.085106383,"of, novel, coronavirus, with"
56179,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.085106383,"to, be, of, may"
56180,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.085106383,"that, of, with, to"
56181,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.085106383,"in, such, similar, to"
56182,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.085106383,"the, to, bat, coronavirus"
56183,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.085106383,"including, to, of, and"
56184,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.085106383,"viruses, related, to, of"
56185,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.085106383,"that, in, and, of"
56186,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.085106383,"coronaviruses, sars-cov-2, and, including"
56187,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.085106383,"the, host, of, sars-cov-2."
56188,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.085106383,"the, evidence, that, to"
56189,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.085106383,"is, the, more, than"
56190,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.085106383,"a, that, the, or"
56191,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.085106383,"a, the, is, sars-cov-2"
56192,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.085106383,"that, the, or, a"
56193,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.085106383,"a, sars-cov-2, is, the"
56194,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.08490566,"from, the, to, that, used, would, of, closest, including"
56195,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.08490566,"to, the, reservoirs, be, and, of, that, have, humans"
56196,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.08490566,"such, as, the, of, to, it, that, is, natural"
56197,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.08490566,"the, of, a, viruses, that, bats, with, however,, researchers"
56198,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.08490566,"the, a, that, with, bat, could, researchers, of, coronavirus"
56199,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.08490566,"the, to, a, of, as, with, bats, and, palm"
56200,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.08490566,"to, the, in, of, sequence, analysis, indicated, that, found"
56201,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.08490566,"that, it, to, such, as, the, of, is, natural"
56202,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.08490566,"that, a, the, animal, or, with, of, in, also"
56203,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.08490566,"also, in, a, of, animal, that, the, with, or"
56204,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.08490566,"the, of, be, to, that, have, humans, and, reservoirs"
56205,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.08490566,"found, in, the, analysis, of, sequence, indicated, that, to"
56206,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.08490566,"a, of, researchers, the, however,, with, viruses, that, bats"
56207,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.08490566,"viruses, to, the, in, and, that, bats, or, for"
56208,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.08490566,"the, of, that, used, to, would, from, including, closest"
56209,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.08490566,"a, of, researchers, the, coronavirus, with, bat, that, could"
56210,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.08490566,"an, a, the, bat, in, receptor, its, by, from"
56211,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.08490566,"on, and, come, are, or, bats, a, may, contaminated"
56212,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.08490566,"bats, are, of, and, a, large, that, in, such"
56213,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.08490566,"and, a, to, the, bats, of, with, palm, as"
56214,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.08490566,"however,, all, sars-cov-2, the, and, in, that, of, is"
56215,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.08490566,"no, by, and, in, to, the, of, sars-cov-2, is"
56216,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.08490566,"is, to, the, that, by, between, and, this, be"
56217,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.08490566,"the, and, of, all, however,, that, in, is, sars-cov-2"
56218,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.08490566,"bats, a, or, and, may, come, contaminated, are, on"
56219,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.08490566,"the, and, of, to, no, in, is, sars-cov-2, by"
56220,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.08490566,"from, the, a, bat, receptor, by, in, its, an"
56221,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.08490566,"the, and, to, that, this, is, between, be, by"
56222,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.08490566,"the, viruses, in, to, that, bats, and, or, for"
56223,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.08490566,"that, bats, in, such, a, and, large, of, are"
56224,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.084745763,"that, the, bats, of, sars-cov-2,"
56225,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.084745763,"and, sars-cov-2, to, other, in"
56226,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.084745763,"the, pandemic, of, virus, from"
56227,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.084745763,"a, of, are, in, viruses"
56228,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.084745763,"of, to, and, the, known"
56229,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.084745763,"and, bats,, with, more, than"
56230,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.084745763,"the, and, to, which, sars-cov"
56231,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.084745763,"the, of, which, to, virus"
56232,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.084745763,"of, and, which, have, to"
56233,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.084745763,"sars-cov, from, humans,, and, with"
56234,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.084745763,"the, infected, with, sars-cov-2, as"
56235,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.084745763,"the, of, with, a, sars-cov-2"
56236,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.084745763,"with, the, of, to, as"
56237,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.084745763,"that, of, a, coronavirus, sars-cov-2"
56238,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.084745763,"it, that, of, sars-cov-2, to"
56239,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.084745763,"to, of, it, that, including"
56240,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.084745763,"is, of, other, coronaviruses, and"
56241,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.084745763,"the, that, sars-cov-2, by, before"
56242,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.084745763,"the, sars-cov-2, is, also, by"
56243,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.084745763,"the, sars-cov-2, in, from, is"
56244,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.084745763,"the, genome, bat, that, to"
56245,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.084745763,"the, to, that, highly, bat"
56246,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.084745763,"found, to, that, of, sars-cov-2"
56247,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.084745763,"of, which, that, as, intermediate"
56248,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.084745763,"and, were, of, which, in"
56249,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.084745763,"which, in, receptor, protein, pangolin"
56250,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.084745763,"of, and, to, in, covs"
56251,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.084745763,"to, have, the, of, and"
56252,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.084745763,"a, as, that, in, bats"
56253,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.084745763,"the, of, as, and, more"
56254,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.084745763,"been, as, and, in, china"
56255,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.084745763,"the, of, wuhan, as, and"
56256,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.084745763,"in, the, market, animal, of"
56257,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.084745763,"that, it, to, is, in"
56258,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.084745763,"the, of, in, this, to"
56259,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.084745763,"the, on, of, is, it"
56260,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.084745763,"the, that, of, is, it"
56261,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.084745763,"most, that, the, of, and"
56262,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.084745763,"of, species, and, that, the"
56263,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.084745763,"and, sars-cov, the, virus, from"
56264,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.084745763,"the, to, and, species, as"
56265,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.084745763,"to, of, the, and, coronaviruses"
56266,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.084745763,"the, other, of, sars-cov-2,, and"
56267,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.084745763,"to, that, are, for, novel"
56268,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.084745763,"in, the, from, to, humans"
56269,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.084745763,"in, the, from, of, sars-cov-2"
56270,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.084745763,"identified, in, the, of, from"
56271,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.084745763,"been, in, as, and, china"
56272,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.084745763,"and, in, been, from, animal"
56273,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.084745763,"in, to, a, high, and"
56274,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.084745763,"are, that, sars-cov-2, nucleotide, and"
56275,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.084745763,"that, was, the, of, and"
56276,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.084745763,"the, and, that, these, have"
56277,"The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.084745763,"the, that, early, were, zoonotic"
56278,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.084745763,"of, zoonotic, the, from, animals"
56279,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.084745763,"from, at, market, the, of"
56280,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.084745763,"and, are, known, to, be"
56281,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.084745763,"the, in, sars-cov-2, with, at"
56282,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.084745763,"been, from, animal, and, in"
56283,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.084745763,"the, viruses, in, human, to"
56284,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.084745763,"a, and, in, their, an"
56285,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.084745763,"in, a, of, to, zoonotic"
56286,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.084745763,"that, a, in, sars-cov-2, the"
56287,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.084745763,"the, of, animal, market, in"
56288,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.084745763,"of, the, cases, in, to"
56289,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.084745763,"the, to, that, a, one"
56290,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.084745763,"may, have, the, from, in"
56291,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.084745763,"that, to, in, it, is"
56292,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.084745763,"to, and, that, was, not"
56293,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.084745763,"as, the, infected, with, sars-cov-2"
56294,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.084745763,"that, sars-cov-2, by, the, before"
56295,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.084745763,"by, with, sars-cov-2, at, the"
56296,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.084745763,"that, a, the, evidence, to"
56297,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.084745763,"in, a, that, the, as"
56298,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.084745763,"that, to, humans, the, in"
56299,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.084745763,"it, in, the, to, that"
56300,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.084745763,"as, a, the, market, in, to, it, evidence, that, from"
56301,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.084745763,"we, that, is, of, the"
56302,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.084745763,"sars-cov-2, is, to, likely, the"
56303,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.084745763,"that, the, market, animals, to"
56304,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.084745763,"the, that, taken, for, of"
56305,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.084745763,"as, and, the, to, that"
56306,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.084745763,"that, of, to, a, species"
56307,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.084745763,"of, that, a, and, to"
56308,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.084745763,"a, to, of, and, they"
56309,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.084745763,"have, in, and, that, animals"
56310,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.084745763,"a, of, the, pandemic, in"
56311,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.084745763,"to, a, high, and, in"
56312,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.084745763,"the, of, that, close, to"
56313,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.084745763,"the, of, to, in, this"
56314,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.084745763,"the, to, in, of, this"
56315,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.084745763,"the, to, in, of, et"
56316,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.084745763,"of, and, a, to, that"
56317,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.084745763,"the, in, a, and, to"
56318,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.084745763,"of, zoonotic, the, to, through"
56319,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.084745763,"the, virus, in, covid-19, originated"
56320,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.084745763,"the, and, that, in, to"
56321,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.084745763,"that, to, humans, in, the"
56322,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.084745763,"origin, the, that, and, in"
56323,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.084745763,"is, and, to, intermediate, be"
56324,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.084745763,"the, natural, host, for, and"
56325,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.084745763,"on, the, of, it, is"
56326,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.084745763,"the, of, a, and, possibility"
56327,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.084745763,"with, the, of, field, is"
56328,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.084745763,"bat, that, the, sars-cov-2, analysis"
56329,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.084745763,"that, of, the, seafood, animals"
56330,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.084745763,"the, of, with, a, or"
56331,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.084745763,"a, in, the, that, or"
56332,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.084745763,"of, possible, that, viruses, bat"
56333,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.084745763,"coronavirus, sars-cov-2, has, to, the"
56334,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.084745763,"to, the, and, sars-cov, which"
56335,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.084745763,"to, the, genome, be, for"
56336,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.084745763,"the, was, and, for, of"
56337,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.084745763,"bats, and, was, found, the"
56338,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.084745763,"and, intermediate, hosts, to, in"
56339,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.084745763,"analysis, that, sars-cov-2, bat, the"
56340,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.084745763,"the, of, as, genetic, bat"
56341,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.084745763,"et, bat, of, sars-cov-2, the"
56342,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.084745763,"a, from, of, are, as"
56343,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.084745763,"a, from, in, the, of"
56344,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.084745763,"the, a, in, are, of"
56345,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.084745763,"that, bats, of, and, have"
56346,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.084745763,"isolated, from, to, in, the"
56347,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.084745763,"and, from, to, may, in"
56348,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.084745763,"and, sars-cov-2, that, the, is"
56349,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.084745763,"sars-cov-2, of, that, to, it"
56350,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.084745763,"to, and, is, be, intermediate"
56351,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.084745763,"of, that, intermediate, host,, to"
56352,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.084745763,"the, and, zoonotic, in, many"
56353,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.084745763,"the, and, zoonotic, viruses, to"
56354,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.084745763,"in, of, for, with, common"
56355,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.084745763,"of, could, be, to, the"
56356,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.084745763,"a, the, beta, to, and"
56357,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.084745763,"the, coronavirus, to, be, of"
56358,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.084745763,"of, with, and, the, approximately"
56359,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.084745763,"of, the, and, with, sars-"
56360,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.084745763,"the, as, of, and, more"
56361,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.084745763,"wuhan, the, of, as, and"
56362,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.084745763,"of, to, the, that, close"
56363,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.084745763,"and, the, et, that, is"
56364,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.084745763,"to, the, animals, market, that"
56365,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.084745763,"that, and, in, china, 2019"
56366,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.084745763,"from, virus, sars-cov, and, the"
56367,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.084745763,"the, has, from, between, and"
56368,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.084745763,"in, a, of, sars-cov-2, with"
56369,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.084745763,"the, identified, from, in, of"
56370,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.084745763,"were, that, these, hosts, for"
56371,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.084745763,"the, most, likely, of, in"
56372,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.084745763,"a, of, bat, in, coronaviruses"
56373,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.084745763,"the, animal, and, other, humans"
56374,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.084745763,"of, the, and, are, other"
56375,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.084745763,"be, of, the, to, sars-"
56376,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.084745763,"that, the, seafood, animals, of"
56377,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.084745763,"the, of, for, that, sars-cov-2"
56378,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.084745763,"of, sars-cov-2, which, the, for"
56379,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.084745763,"in, that, as, a, bats"
56380,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.084745763,"from, in, to, and, may"
56381,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.084745763,"is, that, to, sars-cov-2, coronaviruses"
56382,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.084745763,"to, which, from, a, sars-cov-2"
56383,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.084745763,"sequence, to, and, in, bats"
56384,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.084745763,"to, which, a, from, is"
56385,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.084745763,"the, as, of, sars-cov-2, and"
56386,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.084745763,"that, of, which, intermediate, as"
56387,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.084745763,"that, of, to, intermediate, host,"
56388,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.084745763,"et, al., to, the, as"
56389,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.084745763,"the, of, host, a, that"
56390,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.084745763,"to, the, could, be, of"
56391,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.084745763,"sars-cov-2, of, the, and, to"
56392,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.084745763,"et, the, of, in, to"
56393,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.084745763,"origin, of, the, that, at"
56394,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.084745763,"for, the, of, taken, that"
56395,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.084745763,"the, was, of, for, and"
56396,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.084745763,"a, of, the, between, and"
56397,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.084745763,"in, the, of, to, found, similar, that, this, specific, its"
56398,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.084745763,"as, to, and, the, species"
56399,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.084745763,"have, and, to, the, of"
56400,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.084745763,"the, bats, of, a, china"
56401,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.084745763,"coronaviruses, found, bats, are, of"
56402,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.084745763,"a, and, has, in, the"
56403,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.084745763,"novel, that, are, to, for"
56404,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.084745763,"that, these, were, hosts, for"
56405,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.084745763,"chinese, also, are, that, to"
56406,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.084745763,"that, these, are, also, for"
56407,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.084745763,"of, and, to, zoonotic, in"
56408,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.084745763,"the, and, natural, host, for"
56409,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.084745763,"a, and, were, of, the"
56410,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.084745763,"with, a, the, were, in"
56411,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.084745763,"sars-cov-2, the, with, in, genetic"
56412,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.084745763,"to, the, ered, of, a"
56413,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.084745763,"sars-cov-2, is, coronaviruses, to, that"
56414,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.084745763,"to, the, 2, been, and"
56415,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.084745763,"the, that, sars-cov-2, in, into"
56416,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.084745763,"a, that, species, of, to"
56417,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.084745763,"the, to, that, in, humans"
56418,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.084745763,"and, sars-cov-2, the, in, with"
56419,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.084745763,"not, a, of, zoonotic, the"
56420,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.084745763,"sars-cov-2, of, the, and, that"
56421,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.084745763,"the, et, al., as, to"
56422,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.084745763,"and, to, the, bats, of"
56423,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.084745763,"the, with, sars-cov-2, at, in"
56424,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.084745763,"coronavirus, can, be, that, to"
56425,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.084745763,"the, to, is, and, by"
56426,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.084745763,"the, in, from, is, and"
56427,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.084745763,"at, ratg13, is, the, bats"
56428,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.084745763,"in, to, amino, acid, ratg13"
56429,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.084745763,"et, that, the, and, is"
56430,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.084745763,"that, and, the, of, species"
56431,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.084745763,"sars-cov-2, in, the, with, or"
56432,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.084745763,"and, sars-cov-2, to, in, other"
56433,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.084745763,"the, and, in, with, sars-cov-2"
56434,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.084745763,"the, that, be, in, with"
56435,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.084745763,"to, that, the, and, be"
56436,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.084745763,"sars-cov-2, to, in, the, with"
56437,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.084745763,"the, that, sars-cov-2, in, for"
56438,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.084745763,"these, and, that, have, the"
56439,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.084745763,"the, that, in, it, to"
56440,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.084745763,"the, has, to, that, and"
56441,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.084745763,"has, been, suggesting, that, and"
56442,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.084745763,"the, that, has, been, in"
56443,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.084745763,"and, a, to, the, beta"
56444,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.084745763,"the, rbd, a, to, ace2"
56445,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.084745763,"is, also, sars-cov-2, by, the"
56446,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.084745763,"the, and, is, to, by"
56447,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.084745763,"it, is, sars-cov-2, the, of"
56448,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.084745763,"to, may, sars-cov-2, the, and"
56449,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.084745763,"a, the, possibility, of, and"
56450,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.084745763,"cases, in, the, of, to"
56451,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.084745763,"the, of, cases, in, to"
56452,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.084745763,"in, with, to, sars-cov-2, bat"
56453,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.084745763,"in, found, to, coronavirus, sars-cov-2"
56454,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.084745763,"the, coronaviruses, are, not, of"
56455,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.084745763,"pandemic, from, of, the, virus"
56456,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.084745763,"the, of, sars-cov-2, it, is"
56457,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.084745763,"even, the, it, that, of"
56458,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.084745763,"of, the, sars-cov-2, from, is"
56459,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.084745763,"at, is, the, sars-cov-2, that"
56460,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.084745763,"in, the, of, most, likely"
56461,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.084745763,"the, of, as, sars, and"
56462,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.084745763,"the, of, sars-cov-2, and, as"
56463,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.084745763,"and, the, to, that, sars-cov-2"
56464,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.084745763,"in, the, and, were, to"
56465,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.084745763,"of, to, and, the, in"
56466,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.084745763,"of, the, and, to, in"
56467,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.084745763,"sars-cov-2, a, from, to, which"
56468,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.084745763,"similarity, to, sars-cov-2, the, is"
56469,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.084745763,"the, genetic, sars-cov-2, is, as"
56470,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.084745763,"the, with, sars-cov-2, at, by"
56471,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.084745763,"the, with, a, and, sars-cov-2"
56472,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.084745763,"two, the, sars-cov-2, in, and"
56473,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.084745763,"at, the, with, sars-cov-2, are"
56474,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.084745763,"a, and, were, to, in"
56475,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.084745763,"and, to, human, through, in"
56476,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.084745763,"bat, the, of, as, genetic"
56477,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.084745763,"sars-cov-2, to, be, in, the"
56478,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.084745763,"the, sars-cov-2, to, may, and"
56479,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.084745763,"the, that, early, zoonotic, were"
56480,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.084745763,"between, and, that, the, of"
56481,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.084745763,"a, on, the, by, from"
56482,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.084745763,"evidence, the, that, in, a, as, it, to, from, market"
56483,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.084745763,"the, reservoir, and, it, not, an, with, to, number, of"
56484,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.084745763,"as, the, of, sars, and"
56485,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.084745763,"and, they, many, species, known, to, or, bats, a, be"
56486,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.084745763,"this, found, its, in, the, of, that, to, specific, similar"
56487,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.084745763,"of, the, approximately, and, with"
56488,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.084745763,"and, of, were, in, which"
56489,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.084745763,"the, of, were, a, and"
56490,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.084745763,"that, a, the, and, to"
56491,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.084745763,"is, and, the, that, in"
56492,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.084745763,"from, to, between, and, the"
56493,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","expended to make the simple point 

that COVID-19 had a natural origin.",0.084745763,"a, to, the, that, covid-19"
56494,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","expended to make the simple point 

that COVID-19 had a natural origin.",0.084745763,"the, natural, a, to, that"
56495,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","expended to make the simple point 

that COVID-19 had a natural origin.",0.084745763,"had, to, the, that, a"
56496,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.084745763,"sars-cov-2, a, in, and, has"
56497,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.084745763,"to, the, bats, of, that"
56498,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.084745763,"in, to, is, the, which"
56499,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.084745763,"that, the, is, a, from"
56500,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.084745763,"to, similarity, is, sars-cov-2, the"
56501,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.084745763,"of, shows, similarity, to, in"
56502,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.084745763,"that, the, natural, of, and"
56503,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.084745763,"the, sars-cov-2, a, of, is"
56504,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.084745763,"that, the, of, in, pangolins"
56505,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.084745763,"the, of, that, jumped, to"
56506,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.084745763,"the, with, or, a, of"
56507,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.084745763,"a, with, and, sars-cov-2, the"
56508,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.084745763,"is, the, that, and, scenario"
56509,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.084745763,"to, in, through, and, human"
56510,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.084745763,"one, the, that, a, to"
56511,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.084745763,"that, not, was, to, and"
56512,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.084745763,"the, of, that, a, backbone"
56513,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.084745763,"the, a, that, bat, of"
56514,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.084745763,"in, the, covid-19, virus, originated"
56515,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.084745763,"that, the, backbone, of, a"
56516,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.084745763,"sequence, and, to, in, bats"
56517,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.084745763,"the, of, is, that, bat"
56518,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.084745763,"from, a, is, the, that"
56519,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.084745763,"that, the, of, and, analysis"
56520,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.084745763,"virus, bat, to, of, and"
56521,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.084745763,"that, have, in, animals, and"
56522,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.084745763,"to, the, of, ered, a"
56523,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.084745763,"to, 2, been, and, the"
56524,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.084745763,"the, to, covid-19, a, animals"
56525,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.084745763,"in, the, 2019, and, of"
56526,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.084745763,"and, that, natural, of, the"
56527,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.084745763,"that, pangolins, for, are, in"
56528,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.084745763,"that, the, between, and, guangdong"
56529,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.084745763,"that, be, the, in, with"
56530,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.084745763,"it, that, even, the, of"
56531,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.084745763,"the, have, a, of, in"
56532,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.084745763,"a, the, bats, of, as"
56533,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.084745763,"the, as, a, of, rhinolophus"
56534,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.084745763,"the, and, to, from, between"
56535,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.084745763,"bats, the, was, found, and"
56536,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.084745763,"a, they, of, to, and"
56537,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.084745763,"of, are, as, from, a"
56538,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.084745763,"of, virus, to, bat, and"
56539,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.084745763,"are, known, to, be, and"
56540,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.084745763,"to, bats, they, known, be, and, many, a, species, or"
56541,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.084745763,"the, and, in, from, is"
56542,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.084745763,"is, sars-cov-2, the, of, from"
56543,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.084745763,"in, two, and, sars-cov-2, the"
56544,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.084745763,"in, the, from, an, and"
56545,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.084745763,"from, in, the, may, have"
56546,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.084745763,"is, a, from, to, which"
56547,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.084745763,"to, the, animals, a, covid-19"
56548,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.084745763,"the, of, zoonotic, from, animals"
56549,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.084745763,"the, of, through, to, zoonotic"
56550,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.084745763,"the, of, not, zoonotic, a"
56551,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.084745763,"the, of, to, that, jumped"
56552,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.084745763,"a, of, the, rhinolophus, as"
56553,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.084745763,"of, such, as, humans, and"
56554,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.084745763,"has, been, and, suggesting, that"
56555,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.084745763,"the, sars-cov-2, has, to, coronavirus"
56556,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.084745763,"to, in, and, intermediate, hosts"
56557,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.084745763,"the, in, to, isolated, from"
56558,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.084745763,"the, a, and, has, in"
56559,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.084745763,"has, identity, to, and, be"
56560,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.084745763,"and, of, is, other, coronaviruses"
56561,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.084745763,"as, of, humans, such, and"
56562,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.084745763,"the, has, been, to, of"
56563,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.084745763,"chinese, also, to, that, are"
56564,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.084745763,"the, that, to, a, also"
56565,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.084745763,"field, the, of, is, with"
56566,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.084745763,"also, that, these, are, for"
56567,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.084745763,"as, genetic, is, sars-cov-2, the"
56568,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.084745763,"in, of, sars-cov-2, to, origin"
56569,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.084745763,"protein, receptor, in, which, pangolin"
56570,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.084745763,"by, bat, a, in, the"
56571,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.084745763,"the, by, from, a, on"
56572,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.084745763,"and, identity, has, to, be"
56573,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.084745763,"found, that, of, sars-cov-2, to"
56574,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.084745763,"that, sars-cov-2, nucleotide, and, are"
56575,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.084745763,"bats, are, of, found, coronaviruses"
56576,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.084745763,"that, of, to, sars-cov-2, coronaviruses"
56577,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.084745763,"to, amino, acid, in, ratg13"
56578,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.084745763,"of, to, that, sars-cov-2, bats"
56579,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.084745763,"has, between, and, the, from"
56580,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.084745763,"the, and, that, scenario, is"
56581,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.084745763,"and, the, origin, but, ratg13"
56582,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.084745763,"the, of, be, with, to"
56583,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.084745763,"that, and, be, to, the"
56584,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.084745763,"that, sars-cov-2, to, from, and"
56585,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.084745763,"a, the, also, that, to"
56586,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.084745763,"the, of, from, at, market"
56587,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.084745763,"bat, the, of, sars-cov-2, et"
56588,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.084745763,"in, a, was, from, to"
56589,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.084745763,"similarity, to, in, shows, of"
56590,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.084745763,"of, sars-cov-2, the, which, for"
56591,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.084745763,"ratg13, is, the, sars-cov-2, for"
56592,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.084745763,"also, the, of, to, an"
56593,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.084745763,"to, have, of, and, which"
56594,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.084745763,"in, to, of, which, and"
56595,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.084745763,"that, are, in, pangolins, for"
56596,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.084745763,"sars-cov-2,, other, the, of, and"
56597,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.084745763,"of, the, we, that, is"
56598,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.084745763,"the, of, we, that, is"
56599,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.084745763,"the, genome, to, for, be"
56600,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.084745763,"at, the, bats, is, ratg13"
56601,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.084745763,"is, that, sars-cov-2, the, at"
56602,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.084745763,"with, are, sars-cov-2, at, the"
56603,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.084745763,"sars-cov-2, ratg13, is, the, for"
56604,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.084745763,"likely, the, sars-cov-2, is, to"
56605,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.084745763,"sars-cov-2, to, the, in, with"
56606,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.084745763,"that, the, and, guangdong, between"
56607,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.084745763,"the, that, sars-cov-2, of, are"
56608,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.084745763,"sars-cov-2, of, sequences, the, and"
56609,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.084745763,"sars-cov-2, and, with, the, bat"
56610,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.084745763,"have, and, the, sars-cov-2, origin"
56611,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.084745763,"origin, the, ratg13, and, but"
56612,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.084745763,"and, with, sars-cov-2, to, the"
56613,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.084745763,"and, sars-cov-2, with, the, is"
56614,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.084745763,"of, the, that, between, and"
56615,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.084745763,"more, than, bats,, and, with"
56616,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.084745763,"with, and, sars-cov, humans,, from"
56617,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.084745763,"of, in, the, and, that"
56618,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.084745763,"sars-cov-2, from, to, that, bats"
56619,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.084745763,"bats, to, that, of, sars-cov-2"
56620,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.084745763,"of, that, the, sars-cov-2,, bats"
56621,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.084745763,"the, of, that, is, most"
56622,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.084745763,"has, been, in, the, that"
56623,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.084745763,"that, the, in, or, a"
56624,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.084745763,"of, the, and, an, to, it, with, number, not, reservoir"
56625,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.084745763,"of, bat, coronaviruses, a, in"
56626,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.084745763,"in, a, zoonotic, to, of"
56627,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.084745763,"of, for, common, in, with"
56628,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.084745763,"a, sars-cov-2, with, of, in"
56629,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.084745763,"in, to, of, sars-cov-2, origin"
56630,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.084745763,"and, to, covs, in, of"
56631,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.084745763,"that, are, to, and, of"
56632,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.084745763,"to, in, zoonotic, and, of"
56633,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.084745763,"coronavirus, to, sars-cov-2, found, in"
56634,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.084745763,"to, the, coronavirus, be, of"
56635,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.084745763,"that, to, highly, bat, the"
56636,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.084745763,"of, the, are, in, a"
56637,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.084745763,"a, the, rbd, to, ace2"
56638,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.084745763,"are, the, of, coronaviruses, not"
56639,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.084745763,"of, that, to, it, including"
56640,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.084745763,"of, possible, bat, viruses, that"
56641,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.084745763,"as, of, the, to, with"
56642,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.084745763,"the, of, to, that, with"
56643,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.084745763,"also, of, an, the, to"
56644,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.084745763,"the, many, zoonotic, in, and"
56645,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.084745763,"to, be, the, of, sars-"
56646,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.084745763,"sars-cov-2, genetic, with, the, in"
56647,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.084615385,"we, of, the, have, to, live, animals, in, were, not, that"
56648,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.084615385,"as, of, the, at, and, to, with, for, found, another, suggested"
56649,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.084615385,"that, the, of, in, to, live, animals, were, not, we, have"
56650,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.084615385,"that, the, near, sars-cov-2, to, may, with, high, in, of, and"
56651,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.084615385,"an, with, to, at, the, in, early, of, a, was, animal"
56652,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.084615385,"suggested, as, the, found, to, at, with, of, another, for, and"
56653,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.084615385,"a, the, was, an, animal, with, early, of, in, at, to"
56654,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.084615385,"sars-cov-2, and, of, the, to, in, with, high, that, near, may"
56655,"The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.084577114,"the, of, is, in, different, have, coronavirus, known, to, and, sars-cov-2, it, was, that, bats,, can, by"
56656,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).",0.084577114,"the, that, was, known, to, have, coronavirus, in, is, different, by, of, bats,, can, it, and, sars-cov-2"
56657,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).",0.084577114,"that, a, the, was, animal, humans, human, with, of, in, different, also, discovered, four, 2004, have, to"
56658,"The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.084577114,"the, of, in, a, different, have, animal, four, to, humans, was, discovered, that, 2004, with, also, human"
56659,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.084507042,"a, from, bats, large, of, and"
56660,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.084507042,"bat, and, are, other, viruses, pangolin"
56661,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.084507042,"of, and, which, to, humans,, human"
56662,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.084507042,"in, the, a, coronaviruses, to, and"
56663,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.084507042,"other, sars-cov-2, to, and, is, in"
56664,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.084507042,"other, the, of, and, in, to"
56665,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.084507042,"a, of, the, other, have, to"
56666,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.084507042,"to, the, of, and, have, sars-cov-2"
56667,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.084507042,"the, also, a, in, that, highly"
56668,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.084507042,"are, a, the, of, and, to"
56669,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.084507042,"the, to, many, bat, and, viruses"
56670,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.084507042,"as, of, and, in, that, receptor"
56671,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.084507042,"and, sars-cov-2, reservoirs, to, be, the"
56672,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.084507042,"and, sars-cov-2, that, the, between, origin"
56673,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.084507042,"of, the, and, are, zoonotic, viruses"
56674,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.084507042,"the, and, of, are, as, they"
56675,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.084507042,"and, that, of, receptor, in, as"
56676,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.084507042,"of, and, are, a, in, the"
56677,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.084507042,"to, and, of, is, that, in"
56678,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.084507042,"the, of, and, to, other, sars-cov-2,"
56679,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.084507042,"the, and, to, a, in, coronaviruses"
56680,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.084507042,"that, are, the, and, in, for"
56681,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.084507042,"has, been, identified, that, to, and"
56682,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.084507042,"are, the, of, and, zoonotic, viruses"
56683,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.084507042,"this, of, the, in, which, that"
56684,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.084507042,"in, humans, that, the, and, sars-cov-2"
56685,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.084507042,"of, the, and, zoonotic, to, in"
56686,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.084507042,"that, the, of, two, have, in"
56687,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.084507042,"sars-cov-2, and, to, is, in, other"
56688,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.084507042,"sars-cov-2,, other, the, to, of, and"
56689,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.084507042,"if, are, in, to, virus, be"
56690,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.084507042,"in, and, the, virus, for, of"
56691,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.084507042,"on, the, that, collected, were, market."
56692,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.084507042,"that, were, to, found, in, from"
56693,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.084507042,"that, the, of, this, likely, from"
56694,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.084507042,"analysis, that, the, of, virus, to"
56695,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.084507042,"on, the, that, and, not, a"
56696,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.084507042,"that, the, a, animals, in, and"
56697,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.084507042,"that, the, virus, in, and, of"
56698,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.084507042,"that, the, at, of, virus, and"
56699,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.084507042,"to, an, the, of, evidence, that"
56700,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.084507042,"he, that, the, of, sars-cov-2, and"
56701,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.084507042,"that, market, in, the, was, not"
56702,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.084507042,"the, a, to, and, virus, was"
56703,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.084507042,"of, the, this, that, in, which"
56704,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.084507042,"of, market, in, with, by, the"
56705,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.084507042,"the, and, to, of, in, other"
56706,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.084507042,"the, as, of, to, such, and"
56707,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.084507042,"of, and, a, which, to, that"
56708,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.084507042,"from, and, to, the, of, sars-cov-2"
56709,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.084507042,"the, natural, reservoir, of, and, for"
56710,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.084507042,"the, as, a, of, bat, and"
56711,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.084507042,"the, related, is, reservoir, to, that"
56712,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.084507042,"that, the, market, in, was, not"
56713,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.084507042,"that, of, a, in, with, the"
56714,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.084507042,"the, market, at, isolated, palm, civet"
56715,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.084507042,"that, the, of, sars-cov-2, and, he"
56716,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.084507042,"of, the, bat, and, with, other"
56717,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.084507042,"the, of, a, coronavirus, pangolin, intermediate"
56718,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.084507042,"pangolin, coronaviruses, to, the, of, natural"
56719,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.084507042,"the, with, of, natural, or, as"
56720,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.084507042,"more, to, that, of, and, respectively)"
56721,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.084507042,"a, the, and, on, that, not"
56722,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.084507042,"a, the, and, in, animals, that"
56723,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.084507042,"a, the, coronavirus, of, pangolin, intermediate"
56724,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.084507042,"of, and, the, in, viruses, bat"
56725,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.084507042,"evidence, to, of, the, suggested, that"
56726,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.084507042,"not, a, of, and, the, to"
56727,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.084507042,"host, of, the, in, bats, transmission"
56728,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.084507042,"the, rbd, and, in, to, sars-cov-2,"
56729,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.084507042,"the, is, that, of, and, these"
56730,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.084507042,"the, and, of, to, between, through"
56731,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.084507042,"in, the, of, were, to, human"
56732,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.084507042,"the, of, suggested, that, evidence, to"
56733,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.084507042,"the, viruses, and, bat, many, to"
56734,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.084507042,"the, southern, china, to, in, and"
56735,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.084507042,"are, a, the, of, and, in"
56736,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.084507042,"to, the, bats, as, for, they, and, a, in, of, that, sars-related"
56737,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.084507042,"are, the, sars-cov-2, to, by, of"
56738,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.084507042,"that, are, the, to, of, and"
56739,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.084507042,"that, is, related, to, the, reservoir"
56740,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.084507042,"a, of, the, by, in, to, sars, for, found, that, same, reservoir"
56741,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.084507042,"found, in, by, closely, related, the"
56742,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.084507042,"of, to, the, virus, is, as"
56743,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.084507042,"to, a, in, with, sars-cov-2, the"
56744,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.084507042,"a, bat, to, and, are, more"
56745,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.084507042,"a, in, the, closely, related, to"
56746,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.084507042,"the, that, sars-cov-2, and, in, humans"
56747,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.084507042,"in, the, and, that, sars-cov-2, is"
56748,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.084507042,"a, the, of, and, with, to"
56749,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.084507042,"of, in, the, market, with, by"
56750,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.084507042,"the, of, by, for, reservoir, in, found, a, to, sars, that, same"
56751,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.084507042,"of, the, human, in, to, were"
56752,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.084507042,"an, intermediate, and, the, from, in"
56753,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.084507042,"and, the, of, to, sars-related, as, a, bats, they, that, in, for"
56754,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.084507042,"in, a, of, were, to, with"
56755,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.084507042,"on, the, of, in, and, a"
56756,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.084507042,"these, and, the, of, that, is"
56757,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.084507042,"in, are, that, of, and, sequences"
56758,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.084507042,"the, on, market., that, were, collected"
56759,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.084507042,"the, of, to, through, and, between"
56760,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.084507042,"with, the, to, that, sars-cov-2, is"
56761,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.084507042,"in, to, that, from, were, found"
56762,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.084507042,"from, and, to, that, sars-cov-2, in"
56763,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.084507042,"natural, of, a, to, that, human"
56764,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.084507042,"from, a, spike, to, in, the"
56765,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.084507042,"coronaviruses, to, the, natural, of, pangolin"
56766,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.084507042,"of, in, that, the, to, virus"
56767,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.084507042,"hosts, of, a, diversity, that, as"
56768,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.084507042,"in, the, that, are, and, for"
56769,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.084507042,"in, two, the, of, that, have"
56770,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.084507042,"for, the, natural, reservoir, of, and"
56771,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.084507042,"the, of, and, bat, in, viruses"
56772,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.084507042,"transmission, of, bats, host, in, the"
56773,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.084507042,"the, closely, related, by, in, found"
56774,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.084507042,"intermediate, and, was, by, the, in"
56775,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.084507042,"a, large, of, and, from, bats"
56776,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.084507042,"are, a, to, more, bat, and"
56777,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.084507042,"in, are, if, to, be, virus"
56778,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.084507042,"the, isolated, at, market, civet, palm"
56779,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.084507042,"the, to, in, southern, china, and"
56780,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.084507042,"the, to, which, a, wild, animals"
56781,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.084507042,"the, at, of, virus, and, to"
56782,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.084507042,"in, the, an, intermediate, from, and"
56783,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.084507042,"the, a, which, to, wild, animals"
56784,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.084507042,"the, of, not, to, and, a"
56785,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.084507042,"and, also, a, of, the, to"
56786,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.084507042,"a, the, as, of, bat, and"
56787,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.084507042,"the, be, to, and, reservoirs, sars-cov-2"
56788,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.084507042,"from, a, to, spike, in, the"
56789,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.084507042,"the, have, to, a, of, other"
56790,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.084507042,"intermediate, and, was, in, by, the"
56791,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.084507042,"a, of, sars-cov-2, by, the, in"
56792,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.084507042,"the, natural, of, with, or, as"
56793,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.084507042,"that, are, the, natural, of, for"
56794,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.084507042,"of, that, to, and, more, respectively)"
56795,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.084507042,"that, of, are, and, sequences, in"
56796,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.084507042,"the, sars-cov-2, and, this, origin, of"
56797,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.084507042,"the, a, that, from, to, and"
56798,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.084507042,"a, closely, related, to, in, the"
56799,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.084507042,"by, the, of, sars-cov-2, in, a"
56800,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.084507042,"a, of, in, that, with, the"
56801,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.084507042,"and, are, bat, pangolin, other, viruses"
56802,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.084507042,"of, the, and, other, with, bat"
56803,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.084507042,"the, with, bat, cov, or, pangolin"
56804,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.084507042,"of, the, likely, that, this, from"
56805,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.084507042,"the, origin, that, between, and, sars-cov-2"
56806,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.084507042,"the, bat, cov, or, with, pangolin"
56807,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.084507042,"are, the, they, as, of, and"
56808,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.084507042,"the, sars-cov-2, this, of, origin, and"
56809,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.084507042,"the, sars-cov-2, and, have, to, of"
56810,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV",0.084507042,"of, to, the, virus, that, analysis"
56811,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.084507042,"in, the, of, and, for, virus"
56812,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.084507042,"the, of, to, and, virus, at"
56813,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.084507042,"a, of, to, the, virus, from"
56814,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.084507042,"the, of, by, a, virus, to"
56815,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.084507042,"from, to, by, the, of, a"
56816,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.084507042,"of, with, a, to, were, in"
56817,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.084507042,"to, of, and, humans,, which, human"
56818,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.084507042,"a, of, which, to, that, and"
56819,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.084507042,"of, to, human, natural, a, that"
56820,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.084507042,"of, that, a, diversity, as, hosts"
56821,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.084507042,"also, highly, that, a, the, in"
56822,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.084507042,"the, and, in, rbd, to, sars-cov-2,"
56823,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.084507042,"in, a, and, are, to, the"
56824,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.084507042,"of, is, and, in, that, to"
56825,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.084337349,"are, in, a, of, large, viruses, animal"
56826,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.084337349,"that, the, of, sars-cov-2, and, novel, has"
56827,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.084337349,"and, a, with, other, that, virus, is"
56828,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.084337349,"from, wuhan, to, at, the, in, was"
56829,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.084337349,"the, are, for, of, sars, that, bats"
56830,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.084337349,"a, in, that, for, with, the, to"
56831,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.084337349,"china, have, a, to, animal, in, and"
56832,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.084337349,"and, from, wuhan, at, the, of, was"
56833,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.084337349,"the, wuhan, that, have, of, and, not"
56834,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.084337349,"sars-cov-2, a, and, from, which, that, in"
56835,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.084337349,"and, from, to, at, in, of, on"
56836,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.084337349,"a, of, market, in, animal, positive, the"
56837,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.084337349,"a, of, in, that, only, the, to"
56838,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.084337349,"sars-cov-2, was, viruses, that, are, to, and"
56839,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.084337349,"in, a, of, that, the, as, for"
56840,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.084337349,"found, in, the, are, to, that, have"
56841,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.084337349,"the, of, is, likely, a, to, that"
56842,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.084337349,"the, of, that, evidence, was, to, support"
56843,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.084337349,"the, is, that, of, to, and, an"
56844,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.084337349,"and, from, to, the, according, a, was"
56845,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.084337349,"of, the, bat, cov, and, with, as"
56846,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.084337349,"that, it, human, the, of, has, been"
56847,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.084337349,"evidence, suggests, that, a, or, and, animal"
56848,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.084337349,"and, the, of, infected, are, which, is"
56849,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.084337349,"and, the, of, a, together, with, that"
56850,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.084337349,"a, from, that, sars-cov-2, and, in, which"
56851,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.084337349,"that, the, of, was, to, evidence, support"
56852,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.084337349,"the, is, that, of, to, and, a"
56853,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.084337349,"a, the, with, at, was, of, to"
56854,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.084337349,"and, the, of, to, viruses, in, for"
56855,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.084337349,"and, with, from, the, in, of, collected"
56856,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.084337349,"the, in, of, were, and, shared, with"
56857,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.084337349,"in, a, of, the, that, for, as"
56858,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.084337349,"and, the, be, that, for, sars-cov-2, in"
56859,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.084337349,"in, to, have, the, are, that, found"
56860,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.084337349,"the, is, in, of, to, a, covid-19"
56861,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.084337349,"as, animal, for, the, sars, of, and"
56862,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.084337349,"bats, the, species, of, to, as, and"
56863,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.084337349,"with, other, and, is, a, virus, that"
56864,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.084337349,"and, infected, are, the, of, which, is"
56865,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.084337349,"a, of, the, together, with, that, and"
56866,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.084337349,"of, also, to, which, the, its, in"
56867,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.084337349,"that, a, likely, the, of, is, to"
56868,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.084337349,"in, the, a, that, to, with, for"
56869,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.084337349,"in, the, market, positive, animal, a, of"
56870,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.084337349,"in, only, the, of, that, a, to"
56871,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.084337349,"as, the, animal, for, of, sars, and"
56872,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.084337349,"evidence, suggests, that, a, animal, and, or"
56873,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.084337349,"this, a, that, the, of, and, animals"
56874,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.084337349,"of, the, sars, that, bats, are, for"
56875,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.084337349,"the, in, bats, is, and, available, on"
56876,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.084337349,"at, the, to, was, in, from, wuhan"
56877,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.084337349,"at, of, from, in, and, to, on"
56878,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.084337349,"according, to, a, from, and, was, the"
56879,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.084337349,"the, of, from, and, collected, in, with"
56880,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.084337349,"animal, at, a, and, in, the, to"
56881,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.084337349,"the, of, at, a, in, animal, for"
56882,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.084337349,"and, that, have, not, the, wuhan, of"
56883,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.084337349,"the, of, and, were, in, shared, with"
56884,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.084337349,"the, covid-19, is, of, to, a, in"
56885,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.084337349,"the, of, that, is, a, in, for"
56886,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.084337349,"and, to, at, the, in, a, animal"
56887,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.084337349,"that, and, be, for, sars-cov-2, the, in"
56888,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.084337349,"a, of, the, that, and, in, viruses"
56889,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.084337349,"the, bats, species, to, as, of, and"
56890,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.084337349,"have, animal, to, a, and, in, china"
56891,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.084337349,"of, at, the, in, a, to, animal"
56892,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.084337349,"this, that, the, a, animals, and, of"
56893,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.084337349,"the, in, is, on, available, bats, and"
56894,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.084337349,"viruses, that, was, to, are, and, sars-cov-2"
56895,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.084337349,"the, of, also, to, in, which, its"
56896,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.084337349,"the, also, are, bats, that, for, virus"
56897,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.084337349,"cov, with, bat, the, of, as, and"
56898,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.084337349,"sars-cov-2, of, has, novel, that, and, the"
56899,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.084337349,"for, at, the, in, of, a, animal"
56900,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.084337349,"the, is, that, in, for, of, a"
56901,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.084337349,"the, of, a, to, animal, in, at"
56902,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.084210526,"viruses, to, are, closely, related, in, and, sars-cov-2"
56903,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.084210526,"and, of, infected, bats, with, that, for, virus"
56904,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.084210526,"has, in, the, and, to, that, have, ability"
56905,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.084210526,"the, to, with, bat, and, in, of, known"
56906,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.084210526,"to, the, zoonotic, a, from, high, sequence, isolated"
56907,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.084210526,"with, the, and, of, to, that, is, sars-cov-2"
56908,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.084210526,"that, the, was, studies, of, at, not, have"
56909,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.084210526,"the, of, a, which, in, and, were, at"
56910,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.084210526,"the, a, with, this, and, in, of, at"
56911,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.084210526,"zoonotic, into, humans, of, in, at, least, to"
56912,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.084210526,"the, of, to, it, is, for, humans, by"
56913,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.084210526,"one, evidence, that, the, of, to, as, an"
56914,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.084210526,"and, sars-cov-2, are, closely, related, to, in, viruses"
56915,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.084210526,"the, is, that, to, of, mutations, and, it"
56916,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.084210526,"the, is, and, it, not, would, to, of"
56917,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.084210526,"the, to, in, of, group, that, virus, market"
56918,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.084210526,"by, the, of, a, to, that, and, virus"
56919,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.084210526,"the, to, a, virus, that, and, by, of"
56920,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.084210526,"in, a, to, the, from, bats, and, virus"
56921,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.084210526,"for, and, with, to, at, the, of, was"
56922,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.084210526,"to, the, bats, be, reservoir, of, from, genome"
56923,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.084210526,"a, team, the, from, which, identified, coronavirus, similarity"
56924,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.084210526,"the, that, to, is, mutations, of, it, and"
56925,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).",0.084210526,"the, can, by, these, species, of, known, to, such, as, and, in, been, et, other, also"
56926,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.084210526,"on, the, be, to, and, in, other, may"
56927,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.084210526,"has, to, have, that, in, and, ability, the"
56928,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.084210526,"it, to, the, humans, by, of, is, for"
56929,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.084210526,"a, zoonotic, the, virus, or, of, in, to"
56930,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.084210526,"this, in, the, a, and, of, are, viruses"
56931,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.084210526,"of, and, that, bats, for, virus, infected, with"
56932,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.084210526,"the, of, to, is, result, a, that, this"
56933,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.084210526,"of, that, the, is, bat, a, as, for"
56934,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.084210526,"the, of, three, also, to, by, closely, related"
56935,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.084210526,"from, the, market, a, at, and, of, on"
56936,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.084210526,"studies, that, have, not, the, was, at, of"
56937,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.084210526,"at, least, zoonotic, of, into, humans, in, to"
56938,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.084210526,"the, association, cases, of, suggesting, a, zoonotic, to"
56939,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.084210526,"the, three, also, closely, related, to, by, of"
56940,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.084210526,"is, that, the, for, as, similar, to, a"
56941,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.084210526,"of, the, and, into, or, with, as, sars"
56942,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.084210526,"to, the, high, sequence, a, isolated, from, zoonotic"
56943,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.084210526,"from, genome, bats, to, be, the, reservoir, of"
56944,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.084210526,"a, of, to, that, by, the, and, virus"
56945,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.084210526,"a, number, of, viruses, in, and, to, the"
56946,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.084210526,"of, also, to, ace2, receptors, bats,, the, in"
56947,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.084210526,"that, bats, the, for, a, number, of, and"
56948,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.084210526,"and, the, virus, from, bats, to, a, in"
56949,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.084210526,"a, team, from, the, identified, coronavirus, which, similarity"
56950,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.084210526,"a, of, bat, samples, from, in, identified, coronaviruses"
56951,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.084210526,"with, the, known, and, to, bat, in, of"
56952,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.084210526,"this, with, a, and, of, at, the, in"
56953,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.084210526,"of, was, also, to, ace2, the, its, in"
56954,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.084210526,"in, this, that, the, and, an, of, bat"
56955,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.084210526,"an, and, the, from, or, in, markets, china"
56956,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.084210526,"this, of, and, viruses, are, a, in, the"
56957,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.084210526,"the, from, a, at, market, and, of, on"
56958,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.084210526,"group, of, to, the, market, in, that, virus"
56959,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.084210526,"the, was, to, at, with, of, for, and"
56960,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.084210526,"is, that, the, likely, for, sars-cov-2, to, a"
56961,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.084210526,"association, a, zoonotic, the, cases, of, suggesting, to"
56962,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.084210526,"the, of, a, number, viruses, in, to, and"
56963,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.084210526,"the, of, to, a, that, this, result, is"
56964,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.084210526,"the, of, bat, as, a, that, for, is"
56965,"The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.084210526,"the, of, in, been, species, et, known, to, these, and, can, also, other, such, as, by"
56966,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.084210526,"and, may, be, to, other, on, the, in"
56967,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.084210526,"a, of, the, and, at, in, which, were"
56968,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.084210526,"an, from, in, the, or, markets, china, and"
56969,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.084210526,"the, of, in, bats,, to, also, ace2, receptors"
56970,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.084210526,"the, was, also, to, ace2, in, of, its"
56971,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.084210526,"the, that, for, as, similar, to, a, is"
56972,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.084210526,"the, for, a, to, that, is, sars-cov-2, likely"
56973,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.084210526,"the, of, and, into, sars, or, with, as"
56974,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.084210526,"the, that, to, are, more, than, of, sars-cov-2"
56975,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.084210526,"the, of, a, number, that, bats, and, for"
56976,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.084210526,"the, that, this, bat, and, in, of, an"
56977,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.084210526,"the, to, is, of, it, and, would, not"
56978,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.084210526,"in, a, of, coronaviruses, samples, from, identified, bat"
56979,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.084210526,"that, to, one, as, the, an, of, evidence"
56980,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.08411215,"from, the, to, virus, with, bat, and, human, of"
56981,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.08411215,"some, bat, to, a, in, the, of, and, other"
56982,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.08411215,"to, the, and, of, analysis, that, have, an, humans"
56983,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.08411215,"may, the, palm, for, raccoon, dog, to, is, and"
56984,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.08411215,"we, sars-cov-2, the, and, in, related, not, that, of"
56985,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.08411215,"have, been, and, in, their, to, the, of, sars-cov-2"
56986,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.08411215,"in, one, to, the, from, bats, most, and, at"
56987,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.08411215,"which, the, species, small, to, such, as, and, other"
56988,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.08411215,"to, the, and, is, palm, raccoon, dog, may, for"
56989,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.08411215,"the, analysis, of, and, have, that, an, to, humans"
56990,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.08411215,"direct, to, or, with, of, bats,, and, in, bats"
56991,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.08411215,"at, the, and, in, bats, from, most, one, to"
56992,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.08411215,"to, with, the, of, and, from, bat, virus, human"
56993,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.08411215,"the, and, some, to, a, of, in, other, bat"
56994,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.08411215,"the, of, all, and, in, southern, china, for, markets"
56995,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.08411215,"we, sars-cov-2, and, of, the, related, in, not, that"
56996,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.08411215,"in, for, the, markets, southern, china, all, of, and"
56997,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.08411215,"of, in, bats,, to, bats, with, and, direct, or"
56998,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.08411215,"as, the, to, species, such, small, and, which, other"
56999,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.08411215,"sars-cov-2, and, of, the, have, been, to, in, their"
57000,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.084033613,"at, the, of, and, in, it, that, not, is, most"
57001,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.084033613,"the, that, most, in, is, of, it, and, not, at"
57002,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.084033613,"of, diagnosed, with, had, to, markets, and, the, were, in"
57003,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.084033613,"to, the, bats, and, a, in, of, from, that, coronaviruses"
57004,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.084033613,"the, team, a, that, with, and, researchers, by, of, known"
57005,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.084033613,"the, of, a, to, on, by, taken, with, and, from"
57006,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.084033613,"to, from, a, of, in, bats, the, and, that, coronaviruses"
57007,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.084033613,"in, the, and, of, positive, samples, collected, were, to, from"
57008,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.084033613,"by, a, team, of, researchers, the, that, and, with, known"
57009,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.084033613,"the, by, taken, from, a, and, to, of, on, with"
57010,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.084033613,"and, of, the, to, markets, in, were, diagnosed, with, had"
57011,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.084033613,"in, of, to, the, collected, samples, from, positive, and, were"
57012,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.083969466,"the, that, to, have, in, of, or, and, would, not, sars-cov-2"
57013,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.083969466,"sars-cov-2, of, to, would, have, or, that, not, in, and, the"
57014,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.083969466,"the, as, a, of, that, from, to, civets, infected, by, and"
57015,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.083969466,"the, live, and, were, in, of, a, which, to, at, virus"
57016,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.083969466,"the, of, a, which, to, live, in, and, were, virus, at"
57017,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.083969466,"as, a, of, the, civets, and, by, to, infected, that, from"
57018,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.083832335,"with, the, and, of, a, to, that, were, in, this, sars, likely, be, by"
57019,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.083832335,"in, the, of, a, to, by, with, be, were, and, that, likely, sars, this"
57020,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.083333333,"coronaviruses, a, of"
57021,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.083333333,"bats, a, in"
57022,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.083333333,"of, in, bats, viruses"
57023,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.083333333,"from, the, a, that, and, directly, infect, in, of"
57024,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.083333333,"the, data, that, from"
57025,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.083333333,"sars-cov-2, which, to, human, a, in, and"
57026,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.083333333,"genetic, in, a, to"
57027,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.083333333,"sars-cov-2, and, sars-cov, which, a"
57028,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.083333333,"human, sars-cov-2, are"
57029,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.083333333,"closely, related, in, a, to, genetic"
57030,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.083333333,"which, are, to, and, in, sars-cov, other"
57031,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.083333333,"sars-cov, and, to, sars-cov-2, in, a"
57032,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.083333333,"the, human, virus, and"
57033,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.083333333,"the, of, viruses, pandemic"
57034,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.083333333,"virus, 2, and, the"
57035,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.083333333,"the, of, human, and, within"
57036,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.083333333,"in, a, coronaviruses, are"
57037,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.083333333,"in, species, of"
57038,"Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.083333333,"are, viruses, the"
57039,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.083333333,"the, as, well, viruses"
57040,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.083333333,"two, from, the"
57041,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.083333333,"of, reservoirs, and, the"
57042,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.083333333,"and, bats,, more, that, of"
57043,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.083333333,"with, bats, of, virus"
57044,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.083333333,"that, of, and, animals"
57045,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.083333333,"one, of, with, than"
57046,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.083333333,"that, more, than, >, with, of, and"
57047,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.083333333,"such, and, in, to"
57048,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.083333333,"genetic, sequences, in"
57049,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.083333333,"in, and, sequences"
57050,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.083333333,"in, to, of, and"
57051,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.083333333,"sars-cov-2, to, bats"
57052,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.083333333,"many, in, and"
57053,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.083333333,"of, and, which, in"
57054,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.083333333,"in, to, of"
57055,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.083333333,"of, to, and, which"
57056,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.083333333,"of, to, than"
57057,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.083333333,"of, and, sars-cov-2"
57058,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.083333333,"sars-cov-2, and, in, of"
57059,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.083333333,"of, sars-cov-2, sars-cov"
57060,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.083333333,"in, of, sars-cov-2, to"
57061,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.083333333,"of, and, sequences, by"
57062,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.083333333,"from, of, sequences, bats, and"
57063,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.083333333,"of, and, by, species"
57064,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.083333333,"by, from, and, of"
57065,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.083333333,"than, of, from, species, were, infected, by, and"
57066,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.083333333,"sequences, and, similar, many"
57067,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.083333333,"the, and, sequences, to"
57068,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.083333333,"genetic, the, and, to"
57069,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.083333333,"the, genetic, to"
57070,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.083333333,"to, more, in, is, than, its, sars-cov-2"
57071,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.083333333,"sars-cov-2, to, than, in"
57072,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.083333333,"sars-cov-2, genome, in"
57073,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.083333333,"is, coronavirus"
57074,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.083333333,"in, of, the, are, same"
57075,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.083333333,"are, in, the"
57076,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.083333333,"bats, the, of, are, in, also"
57077,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.083333333,"emergence, the, of"
57078,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.083333333,"in, the, same"
57079,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.083333333,"to, from, of, the, and, with"
57080,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.083333333,"the, to, may, with, of, and, subsequent"
57081,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.083333333,"is, sars-cov-2, the, infected"
57082,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.083333333,"the, of, a, in, to, with, as, used, it"
57083,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.083333333,"the, was, to, a, with, used, as, in, of"
57084,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.083333333,"a, that, sars-cov-2, by"
57085,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.083333333,"have, sars-cov-2, of, that"
57086,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.083333333,"of, a, been"
57087,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.083333333,"sars-cov-2, it, genetic, the"
57088,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.083333333,"to, the, that, been, from"
57089,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.083333333,"it, been, unlike, have"
57090,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.083333333,"coronavirus, been, from"
57091,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.083333333,"human, and, sars-cov-2, to, in, a, which"
57092,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.083333333,"the, virus, which, covid-19, has, in"
57093,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.083333333,"virus, that, an, to, a, human"
57094,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.083333333,"that, the, of, sars-cov-2, and, which, ace2, a"
57095,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.083333333,"the, covid-19, and, of, a, origin, to"
57096,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.083333333,"sars-cov-2, to, have, in, the, or, which"
57097,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.083333333,"the, of, various, that, sars-cov-2, to, a"
57098,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.083333333,"the, and, not, would, an, to, of"
57099,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.083333333,"sars-cov-2, in, a, of, and, the"
57100,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.083333333,"found, in, the, and, to, have"
57101,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.083333333,"the, to, bat, have, and, which, other"
57102,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.083333333,"the, is, have, in, of, to, and, a"
57103,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.083333333,"the, in, sars-cov-2, sequence, by"
57104,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.083333333,"the, also, a, that, in, virus, is, its"
57105,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.083333333,"to, the, a, of"
57106,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.083333333,"a, the, are, to"
57107,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.083333333,"a, and, their"
57108,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.083333333,"and, that, sars-cov-2, is"
57109,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.083333333,"is, and, that, sars-cov-2"
57110,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.083333333,"that, virus, and"
57111,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.083333333,"with, a, shares, and"
57112,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.083333333,"virus, is, with, sars-cov-2"
57113,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.083333333,"to, the, of, all, that"
57114,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.083333333,"the, of, and, that, human, to"
57115,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.083333333,"bat, that, and, human"
57116,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.083333333,"the, identified, natural"
57117,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.083333333,"identical, to, the, that"
57118,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.083333333,"natural, several, to, that, as"
57119,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.083333333,"the, sars-cov, was"
57120,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.083333333,"as, of, virus, and, host"
57121,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.083333333,"on, and, natural, host"
57122,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.083333333,"of, has, been"
57123,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.083333333,"reservoir, a, are, and"
57124,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.083333333,"the, of, viruses, a"
57125,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.083333333,"natural, of, the, a"
57126,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.083333333,"and, the, of, are, natural"
57127,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.083333333,"to, the, human, bat"
57128,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.083333333,"to, ratg13, the, human"
57129,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.083333333,"the, that, human, covid-19, and"
57130,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.083333333,"of, more, and, that, were"
57131,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.083333333,"and, many, sequences, similar"
57132,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.083333333,"of, which, that, pangolin, and"
57133,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.083333333,"analysis, of, that, and"
57134,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.083333333,"in, of, such, as"
57135,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.083333333,"of, in, and, which"
57136,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.083333333,"in, that, and, of"
57137,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.083333333,"between, sars-cov-2, and, of"
57138,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.083333333,"with, and, sars-cov-2"
57139,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.083333333,"in, the, of, and, with"
57140,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.083333333,"with, the, and, of, to, in, is, sars-cov-2"
57141,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.083333333,"to, the, animal, reservoirs"
57142,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.083333333,"its, and, the, to"
57143,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.083333333,"the, and, that, of, to, between"
57144,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.083333333,"can, of, and, the, between"
57145,"the close relation  

between SARS coronavirus and 2019-nCoV",hese reservoirs are the bats,0.083333333,the
57146,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.083333333,"that, the, of, as"
57147,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.083333333,"of, other, as, and"
57148,"zoonotic corona- 

viruses have become an increasing threat to human health,","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.083333333,"zoonotic, viruses, have"
57149,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.083333333,"and, of, the, most"
57150,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.083333333,"the, are, of, they, as"
57151,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.083333333,"the, and, than, viruses"
57152,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.083333333,"the, known, of, than"
57153,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.083333333,"virus, and, as, host, of"
57154,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.083333333,"the, coronavirus, as, in, and"
57155,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.083333333,"of, are, and, for, in, with"
57156,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.083333333,"of, the, coronavirus, and, with"
57157,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.083333333,"and, of, the, to, in, with, their, that, for, coronavirus"
57158,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.083333333,"the, and, in, that, of, is"
57159,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.083333333,"human, and, the, virus"
57160,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.083333333,"that, the, human"
57161,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.083333333,"is, the, thus, that"
57162,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.083333333,"the, of, in, as"
57163,"unnatural origin of SARS-CoV-2, but these people are 

simply wrong","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.083333333,"of, sars-cov-2,"
57164,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.083333333,"of, the, in, sars-cov-2,"
57165,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.083333333,"in, were, sars-cov-2,, the, of"
57166,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.083333333,"the, of, from, hosts"
57167,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.083333333,"sars-cov-2, from, as, to, bats"
57168,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.083333333,"the, spillover, of"
57169,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.083333333,"as, the, of, to, sars-cov-2"
57170,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.083333333,"to, humans, intermediate"
57171,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.083333333,"of, in, the, wuhan"
57172,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.083333333,"as, the, of, and, in"
57173,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.083333333,"probably, has, in"
57174,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.083333333,"and, in, wuhan, china"
57175,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.083333333,"only, of, the, had"
57176,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.083333333,"had, however,, as, in, the, china, of, and"
57177,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.083333333,"the, in, of, probably"
57178,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.083333333,"and, history, of, the"
57179,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.083333333,"infected, to, the, of"
57180,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.083333333,"in, of, animal, that, the"
57181,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.083333333,"that, to, on, the, in"
57182,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.083333333,"the, likely, to, of"
57183,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.083333333,"origin, of, the, in"
57184,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.083333333,"and, in, were"
57185,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.083333333,"seafood, market, in"
57186,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.083333333,"a, sars-cov-2, spillover"
57187,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.083333333,"that, bats, and, the"
57188,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.083333333,"has, been, that, and"
57189,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.083333333,"and, by, the, of, that, been"
57190,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","All human coronaviruses have animal origins, namely, natu- 

ral hosts",0.083333333,"human, coronaviruses"
57191,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.083333333,"bats, the, be, of, and, may"
57192,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.083333333,"may, bats"
57193,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.083333333,"the, that, as, intermediate, to"
57194,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.083333333,"that, palm, civets, from, the, animals, and, transmission"
57195,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.083333333,"covid-19, at, the"
57196,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.083333333,"the, sequence, with"
57197,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.083333333,"at, from, in, to"
57198,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.083333333,"in, to, the, was, is, from"
57199,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.083333333,"the, was, to, at, which"
57200,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",Bats are likely reservoir hosts for SARS-CoV-2,0.083333333,"for, likely"
57201,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",zoonotic origins of SARS-CoV-2 by natural evolution,0.083333333,"evolution, of"
57202,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",zoonotic origins of SARS-CoV-2 by natural evolution,0.083333333,"sars-cov-2, of, natural, zoonotic"
57203,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.083333333,"to, with, the, from"
57204,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.083333333,"sars-cov-2, with, the, origin, is"
57205,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.083333333,"to, coronaviruses, the"
57206,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.083333333,"the, diseases, and"
57207,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.083333333,"of, coronaviruses, and, which"
57208,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.083333333,"of, to, other, and, the"
57209,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.083333333,"and, spread, the"
57210,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.083333333,"the, to, sars-cov"
57211,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.083333333,"was, the, sars-cov"
57212,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.083333333,"in, animals, from"
57213,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.083333333,"of, that, the, in"
57214,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.083333333,"of, lineage, the"
57215,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.083333333,"in, sars-cov-2, the, bat"
57216,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.083333333,"of, the, in, bat"
57217,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.083333333,"the, that, are, for"
57218,"Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.083333333,"the, outbreak, of"
57219,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.083333333,"the, of, sars, outbreak, that"
57220,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.083333333,"of, the, are, that"
57221,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.083333333,"that, for, are"
57222,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.083333333,"that, the, sars"
57223,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.083333333,"coronaviruses, in, are, to, that, and"
57224,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.083333333,"that, and, are, for"
57225,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.083333333,"of, the, sars-cov-2, and, are"
57226,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.083333333,"to, the, can"
57227,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.083333333,"the, of, can, to"
57228,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.083333333,"the, are, to, of, bats, animal, and"
57229,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","with the first case being linked to  

a seafood market",0.083333333,"to, a, with, the"
57230,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","with the first case being linked to  

a seafood market",0.083333333,"to, with"
57231,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","with the first case being linked to  

a seafood market",0.083333333,"the, first"
57232,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","with the first case being linked to  

a seafood market",0.083333333,"a, the"
57233,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.083333333,"the, sars-cov-2, through, from"
57234,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.083333333,"the, in, even, of"
57235,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.083333333,"a, by, the"
57236,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.083333333,"by, and, the"
57237,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.083333333,"the, and, in, by, a, which, that, one"
57238,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.083333333,"in, the, by, and, that"
57239,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.083333333,"the, in, a, that"
57240,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.083333333,"the, a, been"
57241,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.083333333,"to, and, that, its"
57242,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.083333333,"through, that, identified, and, sars-cov-2"
57243,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.083333333,"are, reservoir, a, and"
57244,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.083333333,"sars-cov-2, to, species, and, between"
57245,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.083333333,"and, to, in, china"
57246,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.083333333,"in, a, to, coronaviruses, from, identified, bat, and, similarity"
57247,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.083333333,"coronaviruses, from, a, and, sars-cov-2"
57248,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.083333333,"from, to, between, and"
57249,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.083333333,"in, a, between, and"
57250,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.083333333,"a, from, in, china, to, found"
57251,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.083333333,"in, bat, as, animal"
57252,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.083333333,"a, in, sars-cov-2, from, animal"
57253,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.083333333,"that, the, of, to, evidence, a"
57254,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.083333333,"from, sars-cov-2, the, of"
57255,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.083333333,"the, of, that, natural, a"
57256,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.083333333,"the, and, spread"
57257,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.083333333,"the, that, could, sars-cov-2"
57258,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.083333333,"the, genome, and, that, are"
57259,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.083333333,"are, and, through"
57260,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.083333333,"the, have, that, has"
57261,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.083333333,"the, sars-cov-2, have, and"
57262,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.083333333,"only, have, and, the, through"
57263,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.083333333,"the, and, has, that, are"
57264,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.083333333,"at, of, from, and"
57265,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.083333333,"have, the, of, at, that"
57266,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.083333333,"the, was, at, of, and"
57267,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.083333333,"the, of, and, that, from, nucleotide"
57268,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.083333333,"have, the, bat, ratg13"
57269,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.083333333,"and, of, phylogenetic, at"
57270,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.083333333,"the, and, not, of"
57271,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.083333333,"of, sars-cov-2, into"
57272,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.083333333,"the, that, spillover"
57273,"Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.083333333,"people, the"
57274,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.083333333,"the, spillover, that"
57275,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.083333333,"the, spillover"
57276,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.083333333,"bats, of, sars-cov-2"
57277,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.083333333,"are, to, that, of, sars-cov-2"
57278,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.083333333,"that, the, of, are, from"
57279,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.083333333,"that, of, sars-cov-2, from, the, which"
57280,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.083333333,"the, of, sars-cov-2, humans, and, by"
57281,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.083333333,"are, zoonotic, in, and, humans"
57282,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.083333333,"from, humans, and, the, best"
57283,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.083333333,"the, and, a, in, that, are, of"
57284,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.083333333,"the, of, humans, sars-cov-2"
57285,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.083333333,"the, of, zoonotic"
57286,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.083333333,"the, most, sars-cov-2"
57287,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.083333333,"that, the, of, market, to, animals"
57288,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.083333333,"2019,, the, of, and, huanan"
57289,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.083333333,"the, known, animals, of, that, market, to, and"
57290,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.083333333,"the, of, and, that, through"
57291,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.083333333,"and, b, in, animal"
57292,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.083333333,"in, the, are, we, to, more"
57293,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.083333333,"the, more, to, study"
57294,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.083333333,"to, a, in, the, that"
57295,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.083333333,"we, a, more"
57296,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.083333333,"that, are, more, the, to, in"
57297,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.083333333,"to, that, related, in"
57298,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.083333333,"in, the, of, at, market, a, is, and"
57299,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.083333333,"a, origin, of"
57300,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.083333333,"the, origin, with"
57301,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.083333333,"and, of, is, in"
57302,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.083333333,"the, lineage, of"
57303,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.083333333,"other, the, of, and, in"
57304,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.083333333,"other, and, the, of"
57305,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.083333333,"the, coronavirus, in, of"
57306,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.083333333,"the, to, animal, reservoirs"
57307,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.083333333,"easily, to, human"
57308,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.083333333,"the, to, viruses, closely, related, other, in"
57309,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.083333333,"the, reservoirs, other"
57310,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.083333333,"in, related, sampled, to"
57311,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.083333333,"the, animal, was"
57312,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.083333333,"the, sars-cov-2, and, that"
57313,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.083333333,"their, and, a"
57314,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.083333333,"animal, b, and, in"
57315,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.083333333,"a, nearly, and"
57316,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.083333333,"in, and, a"
57317,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.083333333,"in, and, an"
57318,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.083333333,"at, to, in, from"
57319,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.083333333,"and, from, at, of"
57320,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.083333333,"sars-cov-2, of, into"
57321,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.083333333,"at, of, and, in, on, were"
57322,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.083333333,"to, of, and, from"
57323,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.083333333,"from, to, zoonotic"
57324,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.083333333,"of, sars-cov-2, and, at, two"
57325,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.083333333,"and, of, zoonotic, to"
57326,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.083333333,"of, at, sars-cov-2, in"
57327,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.083333333,"a, and, in, zoonotic"
57328,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.083333333,"sars-cov-2, a, spillover"
57329,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.083333333,"sars-cov-2, from, a, that, with"
57330,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.083333333,"identified, the, natural"
57331,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.083333333,"the, of, yet"
57332,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.083333333,"of, most, the"
57333,Genetic evidence suggesting otherwise is yet to be presented.,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.083333333,"evidence, yet"
57334,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.083333333,"the, of, to, and, were, was"
57335,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.083333333,"more, to, that, of, and"
57336,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.083333333,"of, the, market, those, in"
57337,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.083333333,"the, an, animal, of"
57338,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.083333333,"the, in, of, and, animals, a"
57339,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.083333333,"sars-cov-2, from, including, and, of"
57340,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.083333333,"the, to, one, of"
57341,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.083333333,"two, to, have, a, the"
57342,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.083333333,"in, humans, that, the, sars-cov-2"
57343,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.083333333,"the, of, have, a, to, in, animals"
57344,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.083333333,"from, early, in, the, of"
57345,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.083333333,"sars-cov-2, from, multiple, lineages, of"
57346,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.083333333,"the, of, has, been, to, human, coronavirus"
57347,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.083333333,"is, thought, that, the, initially, humans, animal"
57348,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.083333333,"the, of, to, specific, as, a, that, this, for, is, its"
57349,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.083333333,"and, to, it, that, sars-cov-2, is"
57350,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.083333333,"in, are, to, that, sars-cov-2, and"
57351,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.083333333,"in, is, to, sars-cov-2, that"
57352,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.083333333,"the, are, to, be, and, of"
57353,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.083333333,"in, we, the, are, more, to"
57354,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.083333333,"of, genetic, to, the, and, virus"
57355,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.083333333,"of, viruses, in, and, to, the"
57356,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.083333333,"of, virus, to, and, are, the, for"
57357,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.083333333,"that, wiv, in, collection, is, or, sars-cov-2"
57358,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.083333333,"is, more, than, to, sars-cov-2, in, its"
57359,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.083333333,"is, that, wiv, sars-cov-2, or, in, collection"
57360,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.083333333,"the, most, are, or, more, of, in, and"
57361,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.083333333,"related, coronavirus, to, by, is, sars-cov-2, at, the"
57362,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.083333333,"of, in, that, sars, by, the, or, to, closely, related"
57363,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.083333333,"it, is, that, sars-cov-2, of, related, coronavirus"
57364,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.083333333,"that, sars-cov-2, could, the"
57365,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.083333333,"the, on, were, with, by, as, that, infected, at"
57366,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.083333333,"with, the, by, that, sars-cov-2, as"
57367,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.083333333,"to, in, a, genetic"
57368,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.083333333,"that, the, spillover"
57369,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.083333333,"a, the, in, it, animals, that"
57370,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.083333333,"that, the, two, as, a"
57371,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.083333333,"the, in, a, to, that, genetic"
57372,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.083333333,"to, that, the, evidence"
57373,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.083333333,"is, the, to, was, in, from"
57374,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.083333333,"have, to, for, the, of, market, that"
57375,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.083333333,"was, from, that, are, to"
57376,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.083333333,"this, to, that, the, of, is"
57377,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.083333333,"were, at, of, in, and, on"
57378,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.083333333,"the, that, in, a, it, animals"
57379,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.083333333,"the, is, of, a, virus, in"
57380,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.083333333,"at, a, and, in, the, that"
57381,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.083333333,"from, to, covid-19"
57382,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.083333333,"in, to, from, an"
57383,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.083333333,"that, naturally, to"
57384,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.083333333,"to, a, in, animal"
57385,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.083333333,"from, a, to, wuhan"
57386,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.083333333,"in, animal, from, that, to, a, is, evidence"
57387,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.083333333,"a, to, that, there, covid-19, in, is, animal"
57388,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.083333333,"to, is, that, in"
57389,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.083333333,"he, to, is, sars-cov-2, the"
57390,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.083333333,"a, of, to, that, by, the"
57391,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.083333333,"that, have, by, a, of, to, the"
57392,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.083333333,"the, all, of, that, to"
57393,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.083333333,"that, have, the, at, of"
57394,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.083333333,"of, to, have, the, that, market, for"
57395,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.083333333,"for, the, of, that, taken, evidence, to"
57396,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.083333333,"the, market, of, evidence, to"
57397,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.083333333,"multiple, to, for, the, of, that, have"
57398,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.083333333,"animals,, and, from"
57399,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.083333333,"the, with, a, and"
57400,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.083333333,"bat, the, with, that"
57401,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.083333333,"this, that, were, from, the, animals, and"
57402,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.083333333,"the, and, this"
57403,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.083333333,"coronaviruses, of, a"
57404,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.083333333,"of, to, coronaviruses"
57405,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.083333333,"that, species, and"
57406,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.083333333,"species, to, and"
57407,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.083333333,"and, they, species, to, a"
57408,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.083333333,"of, and, have, to"
57409,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.083333333,"and, that, of"
57410,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.083333333,"cov, and, that, human"
57411,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.083333333,"in, from, animals"
57412,"insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.083333333,"from, animals,, and"
57413,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.083333333,"that, from, which, animals"
57414,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.083333333,"and, other, in"
57415,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.083333333,"have, that, in, animals"
57416,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.083333333,"in, that, origin"
57417,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.083333333,"in, that, from, human"
57418,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.083333333,"of, and, the, in"
57419,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.083333333,"was, the, in, of"
57420,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.083333333,"the, and, in, horseshoe"
57421,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.083333333,"was, in, and, the"
57422,"atural  

selection in an animal host before zoonotic  

transfer;","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.083333333,"in, host"
57423,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.083333333,"easily, human, to"
57424,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.083333333,"to, animals, and"
57425,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.083333333,"and, from, is, to"
57426,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols,",0.083333333,"and, is, to, human"
57427,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.083333333,"and, to, the, a"
57428,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.083333333,"that, a, and"
57429,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.083333333,"very, and, that, to"
57430,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.083333333,"and, the, covid-19, was"
57431,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.083333333,"the, a, genome, and"
57432,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.083333333,"the, high, to"
57433,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.083333333,"to, a, the, and, that"
57434,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.083333333,"and, bat, a, the"
57435,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.083333333,"the, first, that, was, to, a, coronavirus, and"
57436,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.083333333,"the, and, that, coronavirus, a"
57437,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.083333333,"to, and, that, bat"
57438,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.083333333,"was, the, as, of"
57439,"atural  

selection in an animal host before zoonotic  

transfer;","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.083333333,"animal, host"
57440,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.083333333,"in, the, a, with"
57441,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.083333333,"in, the, a, of"
57442,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.083333333,"close, to, the, of"
57443,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.083333333,"in, the, market, those, of"
57444,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.083333333,"the, of, which, that"
57445,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.083333333,"the, that, of, or, they"
57446,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.083333333,"closer, to, than"
57447,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.083333333,"that, the, than, which"
57448,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.083333333,"to, that, the, of, than"
57449,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.083333333,"wuhan, the, in, of"
57450,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.083333333,"in, through, the, covid-19"
57451,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.083333333,"in, such, to, and"
57452,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.083333333,"other, and, in, the, of"
57453,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.083333333,"and, as, n, et, to, in"
57454,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.083333333,"this, and, to, the, in"
57455,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.083333333,"of, from, and, to"
57456,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.083333333,"to, an, the, of, that"
57457,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.083333333,"that, the, of, and, which"
57458,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.083333333,"an, which, of"
57459,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.083333333,"from, and, to, the, of, that"
57460,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.083333333,"is, to, the, which"
57461,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.083333333,"a, the, and, virus, that, is"
57462,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.083333333,"that, the, as, sars-cov-2, and"
57463,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.083333333,"the, is, a, virus, to, that"
57464,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.083333333,"that, and, sars-cov-2, a"
57465,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.083333333,"and, that, of, which, pangolin"
57466,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.083333333,"to, the, has, from, and"
57467,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.083333333,"with, the, and, for, of, a, to, that, covid-19"
57468,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.083333333,"the, of, and, that, coronavirus, a"
57469,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Bats have been reported as being the rich source of 

coronaviruses",0.083333333,"of, the, been"
57470,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Bats have been reported as being the rich source of 

coronaviruses",0.083333333,"the, of, reported"
57471,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.083333333,"the, coronavirus, from, to"
57472,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.083333333,"the, has, to"
57473,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.083333333,"the, similarity, to"
57474,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.083333333,"the, coronavirus, has, a"
57475,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.083333333,"with, the, to, sars-cov-2, pangolin"
57476,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.083333333,"from, to, the, coronavirus, sars-cov-2"
57477,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.083333333,"the, of, infected, to"
57478,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.083333333,"and, pangolins, the, from"
57479,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.083333333,"with, the, of, humans"
57480,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.083333333,"with, bat, the, sars-cov-2"
57481,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.083333333,"the, has"
57482,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.083333333,"sars-cov-2, has"
57483,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.083333333,"the, sars-cov-2, has"
57484,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.083333333,"and, analysis, that, of"
57485,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.083333333,"the, of, and, to, genetic, virus"
57486,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.083333333,"that, the, of, to, a, by"
57487,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.083333333,"to, date, that"
57488,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.083333333,"the, and, of, a, to, that, sars-cov-2, by"
57489,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus",0.083333333,"virus, sars-cov-2, the, of"
57490,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.083333333,"one, the, of, to"
57491,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.083333333,"is, of, and"
57492,"zoonotic corona- 

viruses have become an increasing threat to human health,","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.083333333,"to, human"
57493,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.083333333,"be, possible, hosts"
57494,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.083333333,"sequences, of, by, and"
57495,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.083333333,"by, of, the, that, and, suggesting"
57496,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.083333333,"of, that, the, is, animal"
57497,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.083333333,"a, in, bats"
57498,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.083333333,"the, its, to, and"
57499,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.083333333,"the, a, in, to, bats, and, virus, china"
57500,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.083333333,"and, are, to, bats, a"
57501,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.083333333,"the, a, virus"
57502,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.083333333,"to, the, that, may"
57503,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.083333333,"the, of, is, to, infectious"
57504,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.083333333,"the, of, sequencing, bats, and"
57505,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.083333333,"in, to, the, has, and"
57506,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.083333333,"of, and, are, in, the"
57507,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.083333333,"in, the, animals, of, virus, was, to, is, and"
57508,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.083333333,"virus, in, is, the, of"
57509,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.083333333,"covid-19, in, to"
57510,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.083333333,"been, to"
57511,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.083333333,"of, was, the"
57512,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.083333333,"the, that, naturally"
57513,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.083333333,"natural, and, to, that, in"
57514,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.083333333,"that, its, and, to"
57515,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.083333333,"in, the, animal, and"
57516,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.083333333,"the, sars-cov, is, and"
57517,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.083333333,"that, and, in"
57518,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.083333333,"had, to, animal, in, the, virus, and"
57519,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.083333333,"and, the, that"
57520,"ARS-CoV-2 is a 

natural virus, not a lab-created one.",COVID-19 is a potential zoonotic disease,0.083333333,a
57521,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.083333333,"and, with, the"
57522,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.083333333,"also, and, the, with"
57523,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.083333333,"and, identity, to, be, the"
57524,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.083333333,"intermediate, host, for, the"
57525,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.083333333,"and, the, to, civet, while, sars-cov, their, for, may"
57526,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.083333333,"is, to, the, and, be"
57527,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.083333333,"the, is, and, sars-cov"
57528,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.083333333,"on, the, bat, of, and"
57529,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.083333333,"the, people"
57530,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.083333333,"the, be, or, could"
57531,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.083333333,"infected, the"
57532,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.083333333,"the, be, they"
57533,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.083333333,"the, or"
57534,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.083333333,"the, or, from, in"
57535,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.083333333,"the, market, from"
57536,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.083333333,"common, in, may, the"
57537,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.083333333,"or, the, in, may"
57538,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.083333333,"were, and, in"
57539,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.083333333,"the, only, in"
57540,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.083333333,"and, the, but, clusters"
57541,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.083333333,"to, the, bats, could, be"
57542,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.083333333,"bats, to, related, that"
57543,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.083333333,"revealed, that, the, to, severe, related"
57544,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.083333333,"the, that, could, is"
57545,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.083333333,"it, the, in"
57546,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.083333333,"scientists, that, the"
57547,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.083333333,"a, animals, the, it"
57548,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.083333333,"in, the, of, that, was"
57549,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.083333333,"from, at, market, that, the"
57550,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.083333333,"bats, of, be, the"
57551,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.083333333,"a, with, the, of, bat"
57552,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.083333333,"the, of, a, genomic, viruses"
57553,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.083333333,"a, possible, with, the"
57554,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.083333333,"however,, the, not, that, of"
57555,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.083333333,"the, that, researchers, but, be"
57556,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.083333333,"to, human, the, coronavirus, of, has, been"
57557,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.083333333,"sars-cov-2, the, of, genome"
57558,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.083333333,"to, sars-cov-2, the, genome"
57559,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.083333333,"has, the, genome"
57560,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.083333333,"the, for, sars-cov-2, host"
57561,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.083333333,"a, the, which, sars-cov-2"
57562,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.083333333,"the, host, for, which"
57563,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.083333333,"study, the, more, to"
57564,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.083333333,"infectious, to, is, of, the"
57565,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.083333333,"of, the, genome, sars-cov"
57566,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.083333333,"similar, of, sars-cov, bat"
57567,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.083333333,"of, similar, to, the, for"
57568,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.083333333,"at, the, to, which, was"
57569,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.083333333,"and, the, was, at, of"
57570,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.083333333,"with, the, of, infection"
57571,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.083333333,"the, of, and, which, with"
57572,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.083333333,"the, be, found, with, which"
57573,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.083333333,"and, of, with, at, rbd"
57574,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.083333333,"sars-cov, to"
57575,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.083333333,"human, in, to"
57576,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.083333333,"in, to, human, and"
57577,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.083333333,"and, in, to, human"
57578,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.083333333,"sars-cov-2, that, and, the, as"
57579,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.083333333,"sars-cov-2, similarity, sars-cov, mers-cov"
57580,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.083333333,"sars-cov, as, and, the, of, that, sars-cov-2"
57581,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.083333333,"sars-cov-2, the, with, bat, cov"
57582,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","Coronaviruses are naturally hosted and developmentally 

formed by bats.",0.083333333,"and, bats., are, by"
57583,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.083333333,"the, that, human"
57584,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.083333333,"of, the, from, that, are"
57585,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.083333333,"the, has, that, coronaviruses"
57586,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.083333333,"the, that, of, bat, are"
57587,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.083333333,",, of, the, that"
57588,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.083333333,"from, that, the, of, are"
57589,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.083333333,"that, of, sars-cov-2, have"
57590,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.083333333,"the, sequence, similarity, sars-cov-2"
57591,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.083333333,"and, to, sars-cov-2, the, genome"
57592,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.083333333,"several, between, and, teams, et"
57593,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.083333333,"to, spike, sars-cov-2"
57594,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.083333333,"that, may, sars-cov-2, to"
57595,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.083333333,"to, that, may, have"
57596,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.083333333,"the, of, viruses, are, as, a, in"
57597,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.083333333,"are, of, a, in, as"
57598,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.083333333,"is, and, bat, that, bats"
57599,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.083333333,"is, that, on, most"
57600,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.083333333,"have, bats, of, and, that"
57601,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.083333333,"bats, that, of, on, and"
57602,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.083333333,"is, and, bat, that"
57603,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.083333333,"on, bat, of, and"
57604,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.083333333,"covid-19, which, has, virus, in, the"
57605,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.083333333,"in, the, virus, causes, covid-19"
57606,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.083333333,"virus, bats, the"
57607,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.083333333,"in, which"
57608,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.083333333,"in, the, which"
57609,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",Many of these CoVs can infect several animal species as well,0.083333333,"animal, of"
57610,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",Many of these CoVs can infect several animal species as well,0.083333333,"these, as, of, can"
57611,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",Many of these CoVs can infect several animal species as well,0.083333333,"these, animal"
57612,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",Many of these CoVs can infect several animal species as well,0.083333333,"of, these, covs"
57613,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.083333333,"to, human, a, virus, that, an"
57614,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.083333333,"zoonotic, from, to"
57615,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.083333333,"is, a, virus, to, that"
57616,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.083333333,"that, human, a"
57617,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.083333333,"to, that, is"
57618,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.083333333,"is, an, to"
57619,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.083333333,"it, the, animals, a"
57620,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.083333333,"the, from, is, to"
57621,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.083333333,"it, a, to, the"
57622,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.083333333,"coronaviruses, the, to"
57623,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.083333333,"bats, are, to"
57624,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.083333333,"are, to, the, bats"
57625,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.083333333,"coronaviruses, of, to"
57626,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.083333333,"is, the, of, from"
57627,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.083333333,"in, the, of, to, from"
57628,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.083333333,"the, of, closely"
57629,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.083333333,"ecological, in"
57630,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.083333333,"that, suggest, have, origin"
57631,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.083333333,"suggest, that, bat"
57632,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.083333333,"that, they, in"
57633,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.083333333,"suggest, that, have, origin"
57634,"The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.083333333,"the, found"
57635,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.083333333,"from, to, an, in, the"
57636,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.083333333,"the, to, may, and"
57637,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.083333333,"the, from, and, or"
57638,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.083333333,"virus, from, to, and, then"
57639,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.083333333,"have, and, the, to, from"
57640,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.083333333,"and, sars-cov-2, is"
57641,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.083333333,"animal, and, that, sars-cov-2"
57642,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.083333333,"and, that, a"
57643,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.083333333,"has, a, that, and"
57644,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.083333333,"animal, and, is"
57645,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.083333333,"that, a, and, sars-cov-2"
57646,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.083333333,"has, in, probably"
57647,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.083333333,"virus, its, most"
57648,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.083333333,"in, most"
57649,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.083333333,"and, that, the, from"
57650,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.083333333,"the, is, infected, sars-cov-2"
57651,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.083333333,"that, initially, the, thought, animal, humans, is"
57652,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.083333333,"the, and, from, is"
57653,"In the 

case of MERS, dromedaries were the principal host.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.083333333,"the, host."
57654,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.",0.083333333,"and, sars-cov-2, is, the"
57655,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.083333333,"of, more, bats,, and, that"
57656,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.083333333,"to, and, that, very"
57657,"the close relation  

between SARS coronavirus and 2019-nCoV","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.083333333,"close, between, and"
57658,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.083333333,"animal, and, of, is"
57659,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.083333333,"of, sars-cov-2, that, and"
57660,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.083333333,"by, of, that, between, and, limited"
57661,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.083333333,"of, sars-cov-2, to, bats,"
57662,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.083333333,"and, virus, that"
57663,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.083333333,"the, was, with, of, and"
57664,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.083333333,"the, of, and, virus, sequence, with"
57665,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.083333333,"the, of, with, and, in"
57666,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.083333333,"the, covid-19, and, was"
57667,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.083333333,"by, of, the, covid-19, and, with"
57668,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.083333333,"the, of, human, ace2, this"
57669,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.083333333,"the, of, virus, and, in, with"
57670,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.083333333,"analysis, of, the, and"
57671,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.083333333,"2020, and, of, in, the"
57672,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.083333333,"the, whole, genome, in, and"
57673,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",COVID-19 is a zoonotic virus,0.083333333,"virus, covid-19, a"
57674,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",COVID-19 is a zoonotic virus,0.083333333,"is, covid-19, virus"
57675,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.083333333,"of, bats, virus, with"
57676,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.083333333,"covid-19, from, to"
57677,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.083333333,"available, of, the, covid-19, with"
57678,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.083333333,"of, the, covid-19, from"
57679,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.083333333,"from, with, to, be, the"
57680,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.083333333,"and, in, many"
57681,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.083333333,"coronavirus, as, the, and, in"
57682,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.083333333,"the, and, diseases"
57683,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.083333333,"and, in, zoonotic"
57684,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.083333333,"are, the, and, that, to"
57685,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.083333333,"and, in, of, which"
57686,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.083333333,"are, for, of, and, in, with"
57687,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.083333333,"coronaviruses, which, of, and"
57688,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.083333333,"of, associated, with, in"
57689,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.083333333,"in, and, for, of"
57690,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.083333333,"to, bats, could, be, the"
57691,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.083333333,"pangolin, and, coronaviruses, to"
57692,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.083333333,"the, pangolin, and, a, of"
57693,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.083333333,"and, be, intermediate, to, the, with"
57694,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.083333333,"intermediate, bats, and, the, palm"
57695,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.083333333,"to, the, of, sequence, analysis, indicated, that, coronaviruses"
57696,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.083333333,"to, the, results, that"
57697,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.083333333,"coronavirus, the, of, and, with"
57698,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.083333333,"of, the, approximately"
57699,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.083333333,"coronavirus, from, the, to"
57700,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.083333333,"that, of, came, from, the"
57701,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.083333333,"the, coronavirus, was, to"
57702,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.083333333,"that, of, from, to, coronavirus, the"
57703,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.083333333,"the, of, from, and, more"
57704,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.083333333,"revealed, that, of, the"
57705,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.083333333,"of, to, the, bat, novel, and, sars, virus"
57706,"Bats are the second  

largest order of mammals, with over 1,230 species.","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.083333333,"of, with"
57707,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.083333333,"the, sars-cov-2, and, a, other"
57708,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.083333333,"the, sars-cov-2, from, through"
57709,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.083333333,"by, sars-cov-2, the, genome"
57710,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.083333333,"host, sars-cov-2"
57711,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.083333333,"that, sars-, cov-2, is, the"
57712,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.083333333,"the, is, and, between"
57713,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.083333333,"the, and, of, virus"
57714,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.083333333,"the, novel, virus, covid-19"
57715,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.083333333,"a, market, in, that, the, to"
57716,Historical Precedent; SARS & MERS,"the close relation  

between SARS coronavirus and 2019-nCoV",0.083333333,sars
57717,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","the close relation  

between SARS coronavirus and 2019-nCoV",0.083333333,"and, between, the"
57718,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.083333333,"is, and, of, animal"
57719,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.083333333,"wuhan, in, and, china"
57720,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.083333333,"and, that, in"
57721,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.083333333,"in, and, on"
57722,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.083333333,"the, sars-cov, to"
57723,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.083333333,"that, of, to, sequences, the"
57724,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.083333333,"within, the, that, are"
57725,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.083333333,"the, to, that, are, of"
57726,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.083333333,"a, of, the, with, bat"
57727,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.083333333,"in, the, of, a, bat, with, genome, and, from, yunnan"
57728,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.083333333,"a, the, bat, in, from"
57729,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.083333333,"a, in, virus, that, is"
57730,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.083333333,"from, in, sars-cov-2"
57731,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.083333333,"is, in, a, virus, that"
57732,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.083333333,"this, that, is"
57733,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.083333333,"this, bat"
57734,"the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.083333333,"in, sars-cov-2"
57735,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.083333333,"a, sequence, from, that, coronavirus, in"
57736,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.083333333,"the, a, from, intermediate"
57737,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.083333333,"that, the, likely, of"
57738,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.083333333,"a, and, nearly"
57739,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.083333333,"that, the, and, a"
57740,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.083333333,"the, genome, of, sars-cov"
57741,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.083333333,"and, that, of, sars-cov-2"
57742,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.083333333,"that, the, sars-cov-2, with, of, and"
57743,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.083333333,"that, and, are, the, genome"
57744,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.083333333,"are, a, of, the, coronaviruses"
57745,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.083333333,"the, are, to, in, a, of, viruses, that, and"
57746,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.083333333,"of, the, from, that, sars-cov-2, which"
57747,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.083333333,"that, which, animals, from"
57748,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.083333333,"the, of, that, came, from"
57749,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.083333333,"revealed, that, the, of"
57750,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.083333333,"of, which, from, sars-cov-2"
57751,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.083333333,"the, that, of, huanan, seafood"
57752,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.083333333,"that, the, sars-cov-2, samples"
57753,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.083333333,"the, results, that, sars-cov-2, part, of"
57754,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","Bats are natural hosts of many of the known  

coronaviruses",0.083333333,"many, are, known, bats"
57755,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","Bats are natural hosts of many of the known  

coronaviruses",0.083333333,"the, many"
57756,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.083333333,"to, sars-cov-2, from, bats, as"
57757,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.083333333,"n, as, et, and, in, to"
57758,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.083333333,"and, that, is, bats, bat"
57759,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.083333333,"sequence, in, a, coronavirus, from, that"
57760,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.083333333,"sequence, et, al.,, which, sars-cov-2"
57761,"The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.083333333,"is, in, a, coronavirus, species, et, al.,, coronaviruses, to, and, sars-cov-2, that, can, as"
57762,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.083333333,"coronaviruses, to, sars-cov-2, in, that, is"
57763,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.083333333,"and, can, which, that, a"
57764,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.083333333,"in, to, that, sars-cov-2, can"
57765,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.083333333,"in, and, that, sars-cov-2, a"
57766,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.083333333,"that, sars-cov-2, to, and, a"
57767,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.083333333,"sars-cov, and, sars-cov-2, a, which"
57768,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.083333333,"sars-cov-2, of, which, ace2, a, that, and, the"
57769,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.083333333,"at, two, of, sars-cov-2, and"
57770,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.083333333,"the, that, a, as, two"
57771,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.083333333,"sars-cov-2, a, similarity, sars-cov"
57772,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.083333333,"at, a, and, the, that"
57773,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.083333333,"and, at, the, that, of, sars-cov-2, a"
57774,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.083333333,"which, the, of, as, and, sars-cov, et, 2020)"
57775,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.083333333,"the, of, to, which, as"
57776,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.083333333,"currently, the"
57777,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.083333333,"the, pangolin"
57778,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.083333333,"a, the, sars-cov-2, which"
57779,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.083333333,"the, similarity, sars-cov-2, sequence"
57780,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.083333333,"the, sequence, which, sars-cov-2"
57781,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.083333333,"the, a, has"
57782,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.083333333,"from, a, the, which"
57783,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.083333333,"the, a, pangolins,, coronavirus"
57784,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.083333333,"has, a, to"
57785,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.083333333,"and, the, it, that, of, a"
57786,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.083333333,"of, the, similar"
57787,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.083333333,"in, the, of, a, to, with, genome, similar, that"
57788,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.083333333,"a, was, in"
57789,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.083333333,"a, the, strain, in"
57790,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.083333333,"coronaviruses, and, to, pangolin"
57791,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.083333333,"to, related, are"
57792,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.083333333,"he, related, to"
57793,"bats are also important reservoir species for a great 

range of coronaviruses","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.083333333,"a, of"
57794,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.083333333,"the, that, these, may"
57795,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.083333333,"suggest, that, may"
57796,"Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.083333333,"the, infected"
57797,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.083333333,"the, with, of, infection"
57798,"The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.083333333,"the, currently"
57799,"The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.083333333,"the, sources"
57800,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.083333333,"with, human, sars-cov-2"
57801,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.083333333,"2019,, the, huanan, and, of"
57802,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.083333333,"of, unknown, in, and, the"
57803,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.083333333,"the, of, only, had"
57804,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.083333333,"the, of, to, be, that"
57805,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.083333333,"to, the, of, suggesting, that"
57806,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.083333333,"at, the, covid-19"
57807,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.083333333,"to, on, the, is"
57808,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.083333333,"is, to, in, have"
57809,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.083333333,"to, on, the, in"
57810,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.083333333,"bats, the, of, and, to"
57811,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.083333333,"to, the, and, bats"
57812,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.083333333,"was, isolated, in"
57813,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.083333333,"a, the, was, an, of, in, isolated, to"
57814,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.083333333,"to, sars-cov-2, in, from"
57815,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.083333333,"the, horseshoe, bat"
57816,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.083333333,"was, in"
57817,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.083333333,"bat, the, in"
57818,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.083333333,"the, of, that, spillover"
57819,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.083333333,"an, of, the"
57820,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.083333333,"the, of, an, at, that"
57821,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.083333333,"the, that, of, an"
57822,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.083333333,"that, be, an"
57823,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.083333333,"that, the, of, origin"
57824,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.083333333,"and, sars-cov-2"
57825,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.083333333,"the, and, a, of, in"
57826,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.083333333,"the, even, in, of"
57827,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.083333333,"and, a, the, of, pangolin"
57828,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.083333333,"a, of, in, that, for, the"
57829,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.083333333,"of, in, such, as"
57830,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.083333333,"naturally, furin, cleavage"
57831,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.083333333,"of, other, coronaviruses"
57832,"bats are also important reservoir species for a great 

range of coronaviruses","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.083333333,"for, of"
57833,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.083333333,"in, of, the, for"
57834,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.083333333,"has, been, in, the"
57835,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.083333333,"the, and, from, ratg13"
57836,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.083333333,"the, and, of, from, between"
57837,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.083333333,"of, and, the, between"
57838,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.083333333,"pangolins, the, sars-cov-2"
57839,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.083333333,"the, which, sequence, sars-cov-2"
57840,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.083333333,"that, the, sars-cov-2, its"
57841,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.083333333,"of, in, sars-cov-2, ("
57842,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.083333333,"the, human, to"
57843,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.083333333,"believe, the, a, to"
57844,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.083333333,"the, than, to"
57845,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.083333333,"the, by, coronavirus, a"
57846,"ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.083333333,"in, are"
57847,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.083333333,"most, are, in"
57848,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.083333333,"are, including"
57849,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.083333333,"a, as, the, of, and, to"
57850,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.083333333,"a, of, the, genomic, viruses"
57851,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.083333333,"the, of, which, as, to"
57852,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.083333333,"the, viruses, to, of"
57853,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.083333333,"to, the, as, and, a, of, species, high, have"
57854,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.083333333,"the, as, to, a"
57855,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.083333333,"these, viruses, to, the, and"
57856,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.083333333,"the, of, coronaviruses, a, are"
57857,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.083333333,"of, bats, a, found, the"
57858,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.083333333,"the, virus, china"
57859,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.083333333,"the, of, coronaviruses, a"
57860,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.083333333,"a, virus, bats, of, are"
57861,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.083333333,"the, a, coronaviruses, are, of"
57862,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K",0.083333333,"to, human, beings, in"
57863,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.083333333,"a, of, been"
57864,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.083333333,"the, variety, of"
57865,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.083333333,"in, a, and, the"
57866,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.083333333,"in, the, and, of, western"
57867,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.083333333,"that, related, to, bats"
57868,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.083333333,"are, related, to"
57869,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.083333333,"that, bats, to, hosts"
57870,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.083333333,"that, this, novel, bats"
57871,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.083333333,"the, sars-cov-2, to, in, of, and"
57872,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.083333333,"shares, with, and, a"
57873,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.083333333,"the, genome, and, a"
57874,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.083333333,"of, the, sequencing, bats, and"
57875,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.083333333,"from, the, of, for"
57876,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.083333333,"a, of, the, were, and, with"
57877,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.083333333,"with, of, bats,, and, bats"
57878,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.083333333,"of, bats,, the, its"
57879,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.083333333,"the, genome, bats, for"
57880,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.083333333,"it, the, and, of"
57881,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.083333333,"and, 96%, the, of"
57882,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.083333333,"has, sars-cov-2"
57883,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.083333333,"sars-cov-2, similarity, mers-cov, sars-cov"
57884,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.083333333,"similarity, sars-cov-2, sars-cov, a"
57885,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.083333333,"to, a, has"
57886,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.083333333,"sars-cov-2, or"
57887,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.083333333,"sars-cov-2, a, has"
57888,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.083333333,"sars-cov-2, the, genetic, it"
57889,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.083333333,"in, the, it"
57890,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.083333333,"a, the, possible, with"
57891,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.083333333,"a, were, in, the"
57892,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.083333333,"a, host, sars-cov-2"
57893,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.083333333,"for, coronavirus, the, of, and, in, with, that, their, to"
57894,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.083333333,"to, the, and, their, while, civet, may, for, sars-cov"
57895,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.083333333,"that, bat, found, in, yunnan, of, with, sars-cov-2"
57896,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.083333333,"that, were, in, the, while, animals, and, of, animal, may, markets, further"
57897,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.083333333,"coronavirus, and, animals, to, especially, in, who, have, been"
57898,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.083333333,"the, to, bat, human"
57899,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.083333333,"the, of, bat, a, to"
57900,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.083333333,"a, of, to, yunnan, the, bat, most, coronaviruses,"
57901,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.083333333,"the, to, contact, of"
57902,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.083333333,"the, bat, as"
57903,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.083333333,"be, a, the, human"
57904,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.083333333,"the, a, to, bat, of"
57905,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.083333333,"pandemic, viruses, of, the"
57906,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.083333333,"the, viruses, to"
57907,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.083333333,"the, of, that, viruses, to"
57908,"S1/S2 cleavage sites of coronaviruses are frequently modi- 

fied by insertions or deletions (indels) during evolution","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.083333333,"of, coronaviruses, or"
57909,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.083333333,"the, to, that, coronaviruses, of"
57910,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.083333333,"2, and, the, virus"
57911,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.083333333,"the, and, by"
57912,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.083333333,"the, sars-cov-, and, sars-cov-2"
57913,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.083333333,"the, was, to, been"
57914,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.083333333,"the, sars-cov-2, been, and"
57915,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.083333333,"in, the, that, to, related"
57916,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.083333333,"the, wiv, that, to"
57917,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.083333333,"the, in, sars-cov-2, not, with"
57918,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.083333333,"2, has, to, and"
57919,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.083333333,"and, sars-cov-2, with, more, than"
57920,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.083333333,"the, of, coronavirus, that, from, to"
57921,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.083333333,"bats, a, of, the, found"
57922,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.083333333,"the, to, in, a, of, with, is, that, bats"
57923,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.083333333,"the, and, of, coronaviruses"
57924,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.083333333,"sars-cov-2, from, and, the"
57925,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.083333333,"the, which, with, of, and"
57926,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.083333333,"from, and, the, of, sars-cov-2, in"
57927,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.083333333,"coronavirus, similarity, sars-cov-2"
57928,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.083333333,"sars-cov-2, of, in, with, found, that, yunnan, bat"
57929,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.083333333,"bat, in, of"
57930,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.083333333,"sars-cov-2, in, that, of"
57931,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.083333333,"in, of, sars-cov-2, has"
57932,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.083333333,"sars-cov-2, of, with, in, virus"
57933,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.083333333,"the, virus, from, to, human"
57934,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.083333333,"human, the, virus"
57935,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.083333333,"the, that, a, animal"
57936,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.083333333,"the, zoonotic, of"
57937,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.083333333,"and, the, same, sars-cov-2"
57938,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.083333333,"the, to, high"
57939,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.083333333,"the, has, of, to"
57940,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.083333333,"sars-cov-2, has, to, in, the"
57941,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.083333333,"the, has, to, from, and"
57942,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.083333333,"from, the, in, sars-cov-2"
57943,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","bats are also important reservoir species for a great 

range of coronaviruses",0.083333333,"coronaviruses, a, bats, of"
57944,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","bats are also important reservoir species for a great 

range of coronaviruses",0.083333333,"of, for"
57945,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","bats are also important reservoir species for a great 

range of coronaviruses",0.083333333,"of, a"
57946,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.083333333,"the, of, to, in, and, were"
57947,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.083333333,"the, two, from"
57948,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.083333333,"the, two, with"
57949,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.083333333,"the, bat, ratg13,, from"
57950,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.083333333,"2, sars-cov-, the, and"
57951,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.083333333,"sars-cov-2, sequence, et, al.,, which"
57952,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.083333333,"sars-cov-2,, of, with"
57953,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.083333333,"sequence, that, with"
57954,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.083333333,"sequence, of, than"
57955,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.083333333,"that, with, of"
57956,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.083333333,"of, sars-cov-2,, that"
57957,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.083333333,"sars-cov-2, by, the, sequence, in"
57958,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.083333333,"in, the, not, sars-cov-2, with"
57959,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.083333333,"coronaviruses, in, with, sars-cov-2, the"
57960,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).",0.083333333,"sars-cov-2, is, a, and, coronaviruses, species, can, as, et, al.,, to, that, coronavirus, in"
57961,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.083333333,"to, coronavirus, that"
57962,"In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.083333333,"in, the, horseshoe, and"
57963,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.083333333,"the, and, to, is, by"
57964,"t is thought 

that SARS-CoV-2 jumped the species barrier and initially infected humans from another animal host.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.083333333,"is, the, and, from"
57965,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.083333333,"the, from, and, ratg13"
57966,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.083333333,"nucleotide, to, ratg13, and"
57967,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.083333333,"in, found, and, similar, to"
57968,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.083333333,"the, to, ratg13, human"
57969,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.083333333,"the, can, to"
57970,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.083333333,"in, can, to"
57971,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.083333333,"the, a, in, to, ace2"
57972,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.083333333,"the, s, protein, to"
57973,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.083333333,"the, rbd, with"
57974,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.083333333,"sars-cov-2, the, rbd, in"
57975,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.083333333,"sars-cov-2, the, with, in, rbd"
57976,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.083333333,"that, it, sars-cov-2, to, and, is"
57977,Many of these CoVs can infect several animal species as well,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.083333333,"of, these, can, as"
57978,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.083333333,"is, of, such, as, and"
57979,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.083333333,"the, of, that, animal, in"
57980,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.083333333,"with, and, also, the"
57981,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.083333333,"than, to, sars-cov-2, in"
57982,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.083333333,"and, to, the, be, with, intermediate"
57983,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.083333333,"in, that, for, with, the, transmission, to"
57984,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.083333333,"the, that, to, humans, hosts, and"
57985,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.083333333,"unlike, it, have, been"
57986,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.083333333,"the, and, have, to, found, in"
57987,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.083333333,"the, that, to, in, it"
57988,"results suggest that the pan- 

golin may be a long-term host of these pathogens.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.083333333,"that, the, may, these"
57989,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.083333333,"the, in, has, been"
57990,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.083333333,"that, are, the, and, have, in"
57991,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.083333333,"and, may, have, the, in"
57992,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.083333333,"the, has, been, that, to, and"
57993,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.083333333,"the, obtained, that, to, and"
57994,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.083333333,"these, to, obtained, found, in"
57995,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.083333333,"the, a, to, in, and, was"
57996,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.083333333,"the, sars-cov-2, to, rbd"
57997,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.083333333,"to, could, be"
57998,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.083333333,"sars-cov-2, to, between, and, species"
57999,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.083333333,"of, the, by, sars-cov-2, and, humans"
58000,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.083333333,"the, to, and, may"
58001,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.083333333,"the, of, species, infect, to"
58002,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.083333333,"the, to, for, spread, of, is, by, and"
58003,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.083333333,"the, is, of, and, also"
58004,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.083333333,"the, from, an, a"
58005,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.083333333,"an, to, a, as, from, the, zoonotic"
58006,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.083333333,"a, the, as"
58007,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.083333333,"the, that, of, to, and, who, a"
58008,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.083333333,"the, sars-cov-2, at"
58009,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.083333333,"several, in, and, were"
58010,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.083333333,"at, in, the"
58011,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.083333333,"in, genetic, sequences"
58012,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.083333333,"the, in, of, that, outbreak"
58013,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.083333333,"the, of, in, market, at, was"
58014,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.083333333,"this, the, that, in"
58015,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.083333333,"in, coronavirus, to, with"
58016,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.083333333,"to, bat, sars-cov-2"
58017,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.083333333,"in, sars-cov-2, with"
58018,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.083333333,"similarity, sars-cov-2, bat"
58019,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.083333333,"found, sars-cov-2, to"
58020,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan",0.083333333,"in, wuhan, of"
58021,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.083333333,"the, of, for, from"
58022,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.083333333,"in, the, sars-cov-2, from"
58023,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.083333333,"the, from, market, of"
58024,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.083333333,"in, the, of, from, that, positive, for, market"
58025,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.083333333,"sequences, from, bats, of, and"
58026,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.083333333,"of, evidence, that, the, a, from"
58027,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.083333333,"sequences, of, sars-cov-2, and, from"
58028,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.083333333,"the, for, host, which"
58029,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.083333333,"the, of, variety"
58030,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.083333333,"the, of, are, bats, infect, for, which"
58031,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.083333333,"the, for, not"
58032,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.083333333,"bats, are, natural, of, which"
58033,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.083333333,"the, that, a, virus, covid-19"
58034,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.083333333,"a, the, of, in, virus, is"
58035,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.083333333,"of, the, covid-19, virus"
58036,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.083333333,"to, the, of, sars-cov-2, in, a"
58037,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.083333333,"the, are, more, most, in, of, or, and"
58038,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.083333333,"most, likely, the, of, and"
58039,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Bats are the second  

largest order of mammals, with over 1,230 species.",0.083333333,"the, bats, of, with"
58040,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","Bats are the second  

largest order of mammals, with over 1,230 species.",0.083333333,"with, of"
58041,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.083333333,"the, and, which, have, to, other, bat"
58042,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.083333333,"coronaviruses, sars-cov-2, including"
58043,all three BANAL series viruses also use ACE2 as an entry receptor.,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.083333333,"viruses, as"
58044,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.083333333,"bats, intermediate, and, the"
58045,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.083333333,"sars-cov-2, likely, to"
58046,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.083333333,"that, to, in, sars-cov-2, the"
58047,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.083333333,"the, coronaviruses, and, sars-cov-2"
58048,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.083333333,"in, other, and"
58049,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.083333333,"virus, the, china"
58050,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.083333333,"the, to, for"
58051,zoonotic origins of SARS-CoV-2 by natural evolution,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.083333333,"of, evolution"
58052,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.083333333,"in, the, of, to, bat, sars-related, and, density, species"
58053,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.083333333,"an, the, bat, in"
58054,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.083333333,"the, a, of, and, bat"
58055,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.083333333,"are, in, of, the, and"
58056,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.083333333,"believe, the, to, a"
58057,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.083333333,"the, of, to, species, infect"
58058,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.083333333,"in, a, of, to, single, the, bat, viruses, closely"
58059,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.083333333,"a, of, but, the, to, species"
58060,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.083333333,"the, that, viruses, as"
58061,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.083333333,"bat, the, same, believe, that"
58062,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.083333333,"the, of, same, but"
58063,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.083333333,"is, also, that, a, the, virus, its, in"
58064,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.083333333,"viruses, in, closely, related, to, the, other"
58065,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.083333333,"its, that, to, this, as, the, a, specific, of, is, for"
58066,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.083333333,"of, the, are, as, in, viruses, a"
58067,"Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.083333333,"bats, are, the, for, of, infect, which"
58068,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.083333333,"that, the, of, new, closely, a, bat"
58069,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.083333333,"of, sars-cov-2, from, which"
58070,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.083333333,"with, sars-cov-2,, of"
58071,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.083333333,"of, sars-cov-2, have, from"
58072,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.083333333,"a, of, have, to, from"
58073,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.083333333,"to, sars-cov-2, of, sars-cov-2,"
58074,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.083333333,"a, to, of, sars-cov-2,, common"
58075,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.083333333,"with, of, have, to"
58076,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.083333333,"the, to, related, coronavirus, is, by, sars-cov-2, at"
58077,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.083333333,"the, sars-cov-2, he, is, to"
58078,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.083333333,"the, genome, by, sars-cov-2"
58079,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.083333333,"the, genome, sars-cov-2, to"
58080,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.083333333,"the, sars-cov-2, and, genome, to"
58081,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.083333333,"a, to, the, it"
58082,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.083333333,"by, the, a, in, to, with, and, similar, it"
58083,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.083333333,"and, with, are, to, a, by"
58084,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.083333333,"the, of, to, viruses"
58085,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.083333333,"sars-cov-2, similarity, the"
58086,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.083333333,"sars-cov-2, the, related, of"
58087,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.083333333,"the, by, three"
58088,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.083333333,"sars-cov-2, of, the, viruses, to"
58089,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.083333333,"to, are, the"
58090,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.083333333,"closely, related, to, in, a, genetic"
58091,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.083333333,"genetic, the, that, in, a, to"
58092,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.083333333,"the, virus, is, to, that, of"
58093,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.083333333,"to, is, a, virus, that, the"
58094,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.083333333,"the, is, of, a, natural, to"
58095,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.083333333,"a, in, the, that, to, sars"
58096,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.083333333,"the, that, same, virus, found, in"
58097,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.083333333,"to, that, natural, the, of, is"
58098,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.083333333,"is, to, likely, in, the, same"
58099,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.083333333,"the, of, that, likely, to, a"
58100,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",all three BANAL series viruses also use ACE2 as an entry receptor.,0.083333333,"as, viruses"
58101,"Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",all three BANAL series viruses also use ACE2 as an entry receptor.,0.083333333,"also, as"
58102,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.083333333,"to, of, than"
58103,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.083333333,"to, human, through, have"
58104,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.083333333,"that, to, through"
58105,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","This suggests that the BANAL series may be able to directly infect  

humans.",0.083333333,"this, the"
58106,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","This suggests that the BANAL series may be able to directly infect  

humans.",0.083333333,"the, this, that"
58107,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.083333333,"of, the, in, is"
58108,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.083333333,"in, more, the"
58109,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.083333333,"the, more, in"
58110,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.083333333,"the, in, from, is"
58111,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.083333333,"of, is, the"
58112,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.083333333,"of, from, in"
58113,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.083333333,"the, of, spike, a"
58114,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.083333333,"the, a, to, at, and"
58115,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.083333333,"two, the, a, have, to"
58116,"zoonotic corona- 

viruses have become an increasing threat to human health,","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.083333333,"viruses, have, to"
58117,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.083333333,"a, the, at, have, to"
58118,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.083333333,"bats, in, and"
58119,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.083333333,"bats, and, in"
58120,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.083333333,"the, similar, of"
58121,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.083333333,"similar, of, the"
58122,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.083333333,"the, sars-cov-2, in, bat"
58123,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.083333333,"in, the, may, common"
58124,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.083333333,"a, the, sars-cov-2, and, to"
58125,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.083333333,"the, sars-cov-2, and, to, bat"
58126,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.083333333,"a, to, in, the, may"
58127,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.083333333,"and, with, are, to, a, may"
58128,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.083333333,"in, related, and, genomic, to"
58129,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.083333333,"are, and, a, related, to, in"
58130,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.083333333,"in, the, that, humans, and"
58131,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.083333333,"that, sars-cov-2, through, identified, and"
58132,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.083333333,"in, humans, the, that, sars-cov-2"
58133,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.083333333,"covid-19, in, the, through"
58134,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.083333333,"sars-cov-2, in, the, that, is"
58135,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.083333333,"the, that, sars-cov-2, is, it"
58136,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.083333333,"that, be, sars-cov-2, in"
58137,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.083333333,"is, the, be, in"
58138,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.083333333,"the, with, early"
58139,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.083333333,"were, the, several"
58140,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.083333333,"that, the, described"
58141,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.083333333,"the, of, and, suggesting, that, by"
58142,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.083333333,"limited, between, and, that, of, by"
58143,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.083333333,"and, by, with, the, covid-19, of"
58144,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.083333333,"with, available, the, of, covid-19"
58145,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.083333333,"the, by, of, sars-cov-2,, and, that, a"
58146,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.083333333,"from, of, by, and"
58147,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.083333333,"wuhan, from, a, to"
58148,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.083333333,"from, the, market, of"
58149,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.083333333,"the, of, to, on, a"
58150,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.083333333,"from, a, and, with, to, the"
58151,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.083333333,"the, to, was, isolated, in, an, of, a"
58152,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.083333333,"studies, the, to, that, was, a, but, not"
58153,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.083333333,"with, the, of, humans, that, an, exposures, or"
58154,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.083333333,"the, that, to, closely, related, sars, in, by, of, or"
58155,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.083333333,"revealed, that, related, to, severe, the"
58156,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.083333333,"the, in, that, for, a, of"
58157,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.083333333,"that, for, transmission, to, the, in, with"
58158,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.083333333,"than, were, from, of, species, infected, by, and"
58159,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.083333333,"the, market, animals, that, known, to, and, of"
58160,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.083333333,"is, a, and, of, at, the, market, in"
58161,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.083333333,"that, is, evidence, in, from, a, animal, to"
58162,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.083333333,"the, first, to, coronavirus, and, that, was, a"
58163,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.083333333,"in, animals, to, is, of, the, virus, and, was"
58164,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.083333333,"nucleotide, and, that, from, the, of"
58165,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.083333333,"to, for, the, of, evidence, taken, that"
58166,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.083333333,"of, the, sequence, virus, and, with"
58167,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.083333333,"sequence, with, that, and, human, a"
58168,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.083333333,"of, the, outbreak, sars, that"
58169,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.083333333,"from, in, the, of, virus, and"
58170,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.083333333,"of, the, sequence, analysis, indicated, that, to, coronaviruses"
58171,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.083333333,"have, the, of, to, a, high, and, species, as"
58172,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.083333333,"of, had, a, to, and, the, were, in, approximately, known"
58173,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.083333333,"be, of, the, and, zoonotic, high, to, in, analysis, many"
58174,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.083333333,"as, a, of, the, in, it, used, to, with"
58175,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.083333333,"and, the, virus, bats, to, a, in, china"
58176,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.083333333,"it, in, by, a, with, and, similar, to, the"
58177,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.083333333,"in, southern, china, and, by, chinese, were, for, viruses"
58178,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.083333333,"from, to, a, identified, similarity, and, coronaviruses, in, bat"
58179,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.083333333,"and, the, novel, virus, to, sars, of, bat"
58180,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.083333333,"to, the, of, coronaviruses,, yunnan, most, a, bat"
58181,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.083333333,"the, of, bat, in, closely, viruses, a, single, to"
58182,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.083333333,"the, of, more, than, to, and, in, bats"
58183,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.083333333,"the, related, to, for, which, a, from, most"
58184,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.083333333,"a, of, and, that, the, directly, from, in, infect"
58185,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.083333333,"as, a, of, the, in, was, used, to, with"
58186,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.083333333,"genome, a, and, with, the, of, from, bat, in, yunnan"
58187,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.083333333,"a, in, the, with, genome, that, similar, to, of"
58188,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.083333333,"bat, density, and, species, to, in, the, of, sars-related"
58189,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.083333333,"the, in, of, however,, as, and, had, china"
58190,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.083333333,"the, virus, to, and, had, in, animal"
58191,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.083333333,"the, a, zoonotic, from, an, as, to"
58192,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.083333333,"however,, in, cases,, were, to, an, animal"
58193,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.083333333,"from, in, china, the, bat, of, virus, and"
58194,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.083333333,"animals, from, that, transmission, and, the, palm, civets"
58195,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.083333333,"that, were, from, the, and, animals, this"
58196,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.083333333,"and, of, the, markets, animals, animal, in, were, while, further, that, may"
58197,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.083333333,"of, a, markets., markets, and, the, market, were, in"
58198,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.083333333,"the, animal, of, are, bats, and, to"
58199,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.083333333,"the, of, and, that, a, in, viruses, are, to"
58200,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.083333333,"the, of, to, is, for, and, spread, by"
58201,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.083333333,"the, was, to, that, in, with, of, animals"
58202,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.083333333,"the, was, in, that, as, animal, for"
58203,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.083333333,"the, and, have, to, a, of, is, in"
58204,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.083333333,"who, that, the, of, a, and, to"
58205,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.083333333,"that, the, of, all, and, have, in, for"
58206,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.083333333,"the, identified, a, of, that, to, by, and"
58207,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.083333333,"a, the, of, and, in, with, to"
58208,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.083333333,"to, the, were, known, and, a, in, of, had, approximately"
58209,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.083333333,"were, in, the, market, a, markets., and, of, markets"
58210,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.083333333,"that, there, is, covid-19, in, a, animal, to"
58211,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.083333333,"a, of, to, that, sars-cov-2, by, the, and"
58212,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.083333333,"in, this, be, that, the, between, and, of"
58213,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.083333333,"of, the, in, and, 2020"
58214,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.083333333,"were, a, the, in"
58215,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.083333333,"in, a, of, were, to"
58216,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.083333333,"of, on, the, and, to, in"
58217,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.083333333,"origin, of, covid-19, to, a, and, the"
58218,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.083333333,"to, the, of, evidence, market"
58219,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.083333333,"the, of, is, natural, a, to"
58220,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.083333333,"the, spillover, and"
58221,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.083333333,"and, that, the, at"
58222,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.083333333,"a, at, the, and, in, that"
58223,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.083333333,"that, the, and, at, a"
58224,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.083333333,"the, in, a, to, sars, that"
58225,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.083333333,"human, and, of, within, the"
58226,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.083333333,"the, covid-19, and, that, human"
58227,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.083333333,"that, of, the, huanan, seafood"
58228,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.083333333,"the, of, is, also, and"
58229,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.083333333,"the, of, with, and, these"
58230,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.083333333,"the, of, that, in, human, and"
58231,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.083333333,"of, but, also, and, the, one"
58232,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.083333333,"in, the, are, with"
58233,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.083333333,"that, the, of, sars-cov-2, and, at, a"
58234,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.083333333,"the, that, a, of, and, it"
58235,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.083333333,"sars-cov-2, was, from, that, and"
58236,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.083333333,"this, that, sars-cov-2, in, or"
58237,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.083333333,"the, of, that, sars-cov-2, likely, a"
58238,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.083333333,"the, for, spillover, from, and"
58239,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.083333333,"the, of, to, that, between, and"
58240,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.083333333,"the, between, and, of, to, that"
58241,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.083333333,"the, of, in, to, from"
58242,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.083333333,"on, that, is, most"
58243,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.083333333,"virus, most, its"
58244,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.083333333,"to, sars-cov-2, the, humans"
58245,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.083333333,"that, for, sars-cov-2, with"
58246,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.083333333,"to, that, the, for, sars-cov-2"
58247,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.083333333,"is, the, to, its"
58248,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Those who eagerly peddle suggestions of 

laboratory involvement have consistently failed to present 

credible arguments to support their positions.",0.083333333,"of, their, to"
58249,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","expended to make the simple point 

that COVID-19 had a natural origin.",0.083333333,"a, to, the, natural"
58250,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","expended to make the simple point 

that COVID-19 had a natural origin.",0.083333333,"a, that, had, the, to"
58251,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","unnatural origin of SARS-CoV-2, but these people are 

simply wrong",0.083333333,"sars-cov-2,, of"
58252,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","unnatural origin of SARS-CoV-2, but these people are 

simply wrong",0.083333333,"of, but"
58253,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.083333333,"coronaviruses, including, sars-cov-2"
58254,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.083333333,"that, from, to, rhinolophus, and"
58255,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.083333333,"we, the"
58256,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.",0.083333333,"and, the, sources"
58257,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The sources include 

direct zoonotic spillover, cold-chain foodborne transmission, and 

intermediary host species.",0.083333333,"zoonotic, and, the"
58258,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.083333333,"and, of, in, which"
58259,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.083333333,"in, the, of, and, to, viruses"
58260,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.083333333,"in, the, of, and, unknown"
58261,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.083333333,"to, a, in, and"
58262,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.083333333,"the, to, in, of, natural, and"
58263,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.083333333,"in, a, zoonotic, and"
58264,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.083333333,"a, in, was"
58265,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.083333333,"origin, has, an, and"
58266,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.083333333,"in, was, sars-cov-2"
58267,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.083333333,"sars-cov-2, natural, and, zoonotic, in"
58268,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.083333333,"that, sars-cov-2, samples, the"
58269,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.083333333,"sequence, with, that"
58270,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.083333333,"the, a, in, that, bat"
58271,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.083333333,"sars-cov-2, clearly, that, is"
58272,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.083333333,"a, that, or, purposefully"
58273,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.083333333,"our, that, sars-cov-2"
58274,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.083333333,"the, of, is, to, human"
58275,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.083333333,"human, ace2, this, the, of"
58276,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.083333333,"of, the, a, spike"
58277,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.083333333,"the, a, to, of, on"
58278,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.083333333,"another, the, of, sars-cov-2"
58279,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.083333333,"that, related, coronavirus, is, of, it, sars-cov-2"
58280,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.083333333,"sars-cov-2, a, of, that"
58281,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.083333333,"of, related, is"
58282,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.083333333,"is, emerged"
58283,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.083333333,"data, that, the, from"
58284,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.083333333,"virus, the, from"
58285,Genetic evidence suggesting otherwise is yet to be presented.,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.083333333,"genetic, is"
58286,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","atural  

selection in an animal host before zoonotic  

transfer;",0.083333333,"host, animal"
58287,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.083333333,"the, to, similarity"
58288,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.083333333,"bat, to, bats, of, as"
58289,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.083333333,"that, similarity, to"
58290,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.083333333,"the, to, that, bat, of"
58291,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.083333333,"a, to, in, may, the"
58292,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Malayan pangolins (Manis javanica)  

illegally imported into Guangdong province  

contain coronaviruses similar to SARS- 

CoV-22",0.083333333,"pangolins, similar, to"
58293,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.083333333,"sars-cov-2, is, coronaviruses, to, that, in"
58294,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.083333333,"clearly, that, sars-cov-2, is"
58295,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.083333333,"to, the, in, of, that, key"
58296,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.083333333,"coronaviruses, in, to, that, of, sars-cov-2"
58297,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.083333333,"some, sars-cov-2, including, of, coronaviruses"
58298,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.083333333,"of, the, which, that"
58299,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.083333333,"a, and, can, which, that"
58300,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.083333333,"a, natural, that, the"
58301,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.083333333,"the, of, that, which"
58302,"The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.083333333,"the, described, that"
58303,"preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.083333333,"that, of, during"
58304,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.083333333,"sars-cov-2, can, to, that, in"
58305,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.083333333,"the, of, to, in, virus, was"
58306,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.083333333,"the, in, very"
58307,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.083333333,"that, pangolins, sars-cov-2"
58308,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.083333333,"in, the, of, virus"
58309,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.083333333,"sars-cov-2, from, a, and, coronaviruses"
58310,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.083333333,"a, of, the, from, sars-cov-2, and"
58311,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.083333333,"the, from, or, and"
58312,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.083333333,"a, of, the, coronaviruses"
58313,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.083333333,"sars-cov-, and, the, sars-cov-2"
58314,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.083333333,"the, coronaviruses, sars-cov-2, and"
58315,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.083333333,"the, of, more, and"
58316,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.083333333,"the, pangolins, from, and, with, these, however,, of, a"
58317,"This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.083333333,"finding, the, sars-cov-2"
58318,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.083333333,"the, of, is, and, in, that"
58319,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.083333333,"of, the, however,, that, not"
58320,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.083333333,"the, related, sars-cov-2, of"
58321,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.083333333,"is, not, based, the, in"
58322,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.083333333,"based, the, in, and, that"
58323,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.083333333,"is, to, have, in"
58324,"In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.083333333,"in, to, human, beings"
58325,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.083333333,"and, have, been, to, animals, especially, who, in, coronavirus"
58326,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.083333333,"have, through, to, human"
58327,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.083333333,"that, a, the, was, studies, not, but, to"
58328,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.083333333,"the, of, bat, a, closely, new, that"
58329,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.083333333,"that, a, the, virus, in"
58330,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.083333333,"a, the, coronavirus, pangolins,"
58331,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.083333333,"that, a, the, covid-19, virus"
58332,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.083333333,"the, evidence, that, covid-19"
58333,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.083333333,"covid-19, virus, that, the"
58334,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.083333333,"the, of, that, to, and, sars"
58335,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.083333333,"that, the, of, viruses, to"
58336,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.083333333,"the, that, of, human, and, in"
58337,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.083333333,"of, bats, to, in, the"
58338,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.083333333,"sequence, than, of"
58339,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.083333333,"in, of, to, the, bats, and, more, than"
58340,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.083333333,"the, of, and, more"
58341,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.083333333,"to, bats, of, and, more"
58342,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.083333333,"in, the, to, of, bats"
58343,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.083333333,"showed, to, and"
58344,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.083333333,"analysis, the, that"
58345,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.083333333,"the, that, evidence, covid-19"
58346,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.083333333,"from, humans,, and, bats,"
58347,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.083333333,"the, of, that, is, animal"
58348,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.083333333,"from, the, of, covid-19"
58349,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.083333333,"evidence, from, a, of, the, that"
58350,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.083333333,"from, is, the, of, receptor"
58351,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.083333333,"of, is, possible, that, bat"
58352,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.083333333,"of, viruses, the, same"
58353,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.083333333,"the, of, receptor, domain, that"
58354,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.083333333,"that, the, same"
58355,"Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.083333333,"might, the, of"
58356,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.083333333,"the, and, to, of, in"
58357,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.083333333,"bats, to, that, hosts"
58358,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.083333333,"many, a, of"
58359,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.083333333,"through, and, are"
58360,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.083333333,"and, are, zoonotic, in, humans"
58361,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.083333333,"to, in, can"
58362,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.083333333,"to, covs, animals"
58363,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.083333333,"and, in, to, be, are"
58364,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.083333333,"that, be, to, in"
58365,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.083333333,"in, are, to, that"
58366,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.083333333,"in, all, caused"
58367,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",Bats are hosts of many coronaviruses,0.083333333,"are, bats, hosts"
58368,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.083333333,"to, intermediate, humans"
58369,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.083333333,"an, to, viruses, in"
58370,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.083333333,"most, in"
58371,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.083333333,"an, to, however,, animal, in, cases,, were"
58372,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.083333333,"in, an, to"
58373,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.083333333,"the, of, most, that"
58374,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.083333333,"in, the, and, a, of, animals"
58375,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.083333333,"the, of, in, that, outbreak"
58376,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.083333333,"to, in, the, key, that, of"
58377,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.083333333,"in, the, and, are, that, have"
58378,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.083333333,"the, that, have, in, for, of, and, all"
58379,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.083333333,"bats, and, in, all, the"
58380,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.083333333,"the, virus, which, that"
58381,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.083333333,"be, virus, that, the"
58382,"Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.083333333,"the, they, be"
58383,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.083333333,"the, found, be, which, with"
58384,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.083333333,"the, in, found, virus, that, same"
58385,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.083333333,"in, which, were"
58386,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.083333333,"the, results, that, with"
58387,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.083333333,"of, in, associated, with"
58388,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.083333333,"two, the, with"
58389,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.083333333,"that, has, have, the"
58390,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.083333333,"that, have, in, animals"
58391,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.083333333,"to, the, of, contact"
58392,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.083333333,"to, been, was, the"
58393,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.083333333,"the, animals, to, in, of, with, was, that"
58394,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.083333333,"that, with, the, in"
58395,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.083333333,"in, with, the, to, that, of"
58396,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.083333333,"the, of, china, have, a, in"
58397,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.083333333,"that, the, of, is, natural"
58398,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.083333333,"the, three, by"
58399,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.083333333,"is, the, bat"
58400,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.083333333,"of, viruses, in, bats"
58401,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.083333333,"the, of, can, between, and"
58402,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.083333333,"or, in, the, may"
58403,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.083333333,"and, can, bats., or, bats, may"
58404,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.083333333,"with, of, bats, bats,, and"
58405,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.083333333,"to, and, of, bats,, in"
58406,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.083333333,"the, from, and, best, humans"
58407,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.083333333,"and, the, bats, palm, intermediate"
58408,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.083333333,"the, was, in, an"
58409,"All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.083333333,"all, caused, in"
58410,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.083333333,"bats, the, all, and, in"
58411,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.083333333,"the, species, humans, by, and"
58412,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.083333333,"in, species, humans"
58413,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.083333333,"and, virus, to, of, bat"
58414,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.083333333,"bats, are, a, of, virus"
58415,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.083333333,"of, to, bat, bats, as"
58416,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.083333333,"of, more, to, and, bats"
58417,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.083333333,"and, to, of, bat, are, as, they"
58418,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.083333333,"of, to, not, from, bats"
58419,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.083333333,"and, from, to, be, of, bats, are"
58420,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.083333333,"to, are, bats"
58421,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.083333333,"in, recently, to, be"
58422,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.083333333,"sars-cov, and, are, to, in, which, other"
58423,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.083333333,"the, of, and, sars-cov, which, as, et, 2020)"
58424,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.083333333,"a, they, species, to, and"
58425,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.083333333,"are, and, bats, to, a"
58426,"Coronaviruses are naturally hosted and developmentally 

formed by bats.","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.083333333,"are, and, by, bats."
58427,"Bats are natural hosts of many of the known  

coronaviruses","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.083333333,"bats, are, many, known"
58428,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.083333333,"by, a, with, and, are, to"
58429,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.083333333,"are, a, to, may, with, and"
58430,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.083333333,"can, or, bats., and, bats, may"
58431,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.083333333,"bats, or, pangolins, be, on"
58432,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.083333333,"of, the, were, to, and, was"
58433,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.083333333,"in, the, of, a, animals, have, to"
58434,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.083333333,"the, of, in, market, was, at"
58435,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.083333333,"have, a, of, in, the, china"
58436,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.083333333,"a, of, the, at, have, to, virus"
58437,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.083333333,"a, between, and, in"
58438,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.083333333,"a, of, the, and, in"
58439,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.083333333,"and, was, the"
58440,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.083333333,"the, in, a, of, was, and, market"
58441,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.083333333,"sars-cov-2, have, and, the"
58442,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.083333333,"of, have, from, sars-cov-2"
58443,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.083333333,"the, guangdong, wildlife, pangolins, from, and, in, their, of"
58444,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.083333333,"sars-cov-2, from, in, wildlife"
58445,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.083333333,"with, the, of, from, virus"
58446,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.083333333,"sars-cov-2, with, is, virus"
58447,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.083333333,"the, virus, of, with, from"
58448,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.083333333,"of, sars-cov-2, the, virus"
58449,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.083333333,"in, is, of, the, virus"
58450,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.083333333,"of, the, is, receptor, from"
58451,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.083333333,"similar, of, sars-cov-2, from"
58452,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.083333333,"in, sars-cov-2, with, guangdong, the, is"
58453,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.083333333,"sars-cov-2, the, domain, of"
58454,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","t some virus detected in pangolins 

were capable of infecting humans.",0.083333333,"of, in, virus"
58455,"preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.","t some virus detected in pangolins 

were capable of infecting humans.",0.083333333,"some, of"
58456,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","t some virus detected in pangolins 

were capable of infecting humans.",0.083333333,"in, of, virus"
58457,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","t some virus detected in pangolins 

were capable of infecting humans.",0.083333333,"some, pangolins, of"
58458,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.083333333,"several, teams, between, and, et"
58459,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.083333333,"several, were, and, in"
58460,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.083333333,"by, viruses, in, and, were, for, chinese, southern, china"
58461,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.083333333,"in, et, al., found, and"
58462,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.083333333,"for, between, and, in"
58463,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.083333333,"the, and, by, which, a, one, that, in"
58464,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.083333333,"the, on, that, infected, with, were, at, as, by"
58465,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.083333333,"the, of, from, pangolins, with, however,, a, and, these"
58466,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.083333333,"of, the, in, pangolins, from, wildlife, their, guangdong, and"
58467,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.",0.083333333,"bats, the, by"
58468,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.083333333,"which, in"
58469,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.083333333,"pangolins, from, and, the"
58470,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.083333333,"in, the, and, may, have"
58471,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.083333333,"the, bats, intermediate, and"
58472,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.",0.083333333,"viruses, that, of"
58473,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.",0.083333333,"of, that, transmission"
58474,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.083333333,"of, animals, and, that"
58475,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.083333333,"of, the, animals"
58476,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.083333333,"and, this, that, the, is"
58477,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.083333333,"from, to, is, a, the"
58478,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.083333333,"a, to, the, from, which, for, most, related"
58479,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.083333333,"covs, animals, to"
58480,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.083333333,"only, have, through, and, the"
58481,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.083333333,"the, have, from, to, and"
58482,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.083333333,"the, of, species, but, a, to"
58483,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.083333333,"to, of, have, from, a"
58484,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.083333333,"the, of, and, but, one, also"
58485,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.083333333,"the, of, to, not, from"
58486,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.083333333,"that, and, hosts, to, humans, the"
58487,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.083333333,"the, that, of, identified, to, by, and, a"
58488,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.083333333,"that, to, rhinolophus, and, from"
58489,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.083333333,"that, such, as, to, humans"
58490,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.083333333,"a, bat, of, by, the"
58491,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.083333333,"and, bat, that, human"
58492,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.083333333,"sars-cov-2, a, that, and"
58493,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.083333333,"human, with, sars-cov-2"
58494,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.083333333,"and, that, a, sequence, human, with"
58495,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.083333333,"sars-cov-2, with, bat, cov"
58496,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.083333333,"the, in, and, to, from, a"
58497,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.083333333,"the, and, be, identity, to"
58498,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.083333333,"has, the, to, sars-cov-2, in"
58499,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.083333333,"the, from, a, and, to, with"
58500,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.083333333,"the, sars-cov-2, to, therefore,, be, with, in, and"
58501,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.083333333,"the, other, in, spike, and, coronavirus, a"
58502,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.083333333,"the, on, is, and"
58503,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.083333333,"and, in, on"
58504,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.083333333,"and, on, the"
58505,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.083333333,"as, of, and, other"
58506,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.083333333,"such, as, and, of, is"
58507,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.083333333,"and, of, coronaviruses, as"
58508,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","zoonotic corona- 

viruses have become an increasing threat to human health,",0.083333333,"have, zoonotic, viruses"
58509,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","zoonotic corona- 

viruses have become an increasing threat to human health,",0.083333333,"viruses, to, have"
58510,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.083333333,"of, virus, the"
58511,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.083333333,"a, we, more"
58512,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.083333333,"a, analysis, of"
58513,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.083333333,"a, of, natural"
58514,The FCS of SARS-CoV-2 was not bioengineered—full stop.,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.083333333,"of, was"
58515,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.083333333,"analysis, more, likely"
58516,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.083333333,"to, have, a, at, the"
58517,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.083333333,"that, a, or, purposefully"
58518,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.083333333,"the, of, have, a, to, virus, at"
58519,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.083333333,"suggest, the, origin, of, virus"
58520,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.083333333,"the, in, bats,"
58521,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.083333333,"are, by, the"
58522,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.083333333,"the, are, with, in"
58523,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.083333333,"not, in, wildlife"
58524,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.083333333,"the, by, coronavirus, in"
58525,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.083333333,"in, with, the, by, are"
58526,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.083333333,"to, bat, that, sars-cov-2"
58527,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.083333333,"bat, that, a, in, to"
58528,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.083333333,"sars-cov-2, in, from, wildlife"
58529,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.083333333,"in, not, wildlife"
58530,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.083333333,"a, from, in, that, to"
58531,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.083333333,"sars-cov-2, a, an"
58532,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.083333333,"through, that, to"
58533,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.083333333,"a, sars-cov-2, to, that"
58534,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.083333333,"humans, with, the, of"
58535,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.083333333,"that, is, could, the"
58536,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.083333333,"of, that, the, with, or"
58537,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.083333333,"that, the, an, humans, or, with, of, exposures"
58538,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.083333333,"that, the, humans, of"
58539,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.083333333,"that, the, with, of"
58540,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.083333333,"as, that, to, humans, such"
58541,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.083333333,"to, sars-cov-2, as"
58542,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.083333333,"has, been, of"
58543,"Bats are natural hosts of many of the known  

coronaviruses","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.083333333,"many, the"
58544,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.083333333,"sars-cov, and, sars-cov-2, to, in, a"
58545,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.083333333,"been, that, and, the, of, by"
58546,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.083333333,"have, to, for, the, multiple, of, that"
58547,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.083333333,"that, the, of, as, sars-cov-2, and, sars-cov"
58548,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.083333333,"this, to, that, the, of, and"
58549,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","S1/S2 cleavage sites of coronaviruses are frequently modi- 

fied by insertions or deletions (indels) during evolution",0.083333333,"of, or, coronaviruses"
58550,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","S1/S2 cleavage sites of coronaviruses are frequently modi- 

fied by insertions or deletions (indels) during evolution",0.083333333,"insertions, of, s1/s2, cleavage"
58551,Bats are likely reservoir hosts for SARS-CoV-2,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.083333333,"likely, for"
58552,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.083333333,"zoonotic, for, the"
58553,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.083333333,"that, sars-cov-2, humans, in"
58554,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.083333333,"has, been, in, that"
58555,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.083333333,"species, humans, in"
58556,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.083333333,"the, history, of, and"
58557,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.083333333,"the, virus, human"
58558,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.083333333,"is, and, the, that"
58559,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.083333333,"are, the, they, as, of"
58560,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.083333333,"of, the, that, they, or"
58561,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.083333333,"that, are, for, sars-cov-2"
58562,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.083333333,"in, has, of, sars-cov-2"
58563,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.083333333,"to, the, in, and, evidence"
58564,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.083333333,"a, the, from, bat, in"
58565,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.083333333,"a, strain, in, the"
58566,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.083333333,"bat, an, in, the"
58567,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.083333333,"the, in, not, based, is"
58568,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.083333333,"is, the, by, from, an"
58569,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.083333333,"based, on, the, in, binding, protein"
58570,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.083333333,"2, to, has, and"
58571,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.083333333,"nucleotide, and, to, ratg13"
58572,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.083333333,"could, be, to"
58573,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.083333333,"to, are, that, was, from"
58574,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.083333333,"from, and, sars-cov-2"
58575,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.083333333,"and, that, was, sars-cov-2, from"
58576,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.083333333,"from, and"
58577,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.083333333,"in, that, coronaviruses, are, to, and"
58578,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.083333333,"on, and, that, bats, of"
58579,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.083333333,"coronaviruses, to, sars-cov-2, in, that, of"
58580,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.083333333,"of, that, to, which, and"
58581,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.083333333,"one, of, than, with"
58582,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.083333333,"genome, of, with, bat"
58583,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.083333333,"of, sars-cov-2, these"
58584,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.083333333,"of, with, one, sars-cov-2"
58585,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.083333333,"the, as, that"
58586,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.083333333,"that, the, viruses"
58587,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.083333333,"that, the, as, viruses"
58588,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.083333333,"wiv, that, the"
58589,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.083333333,"the, from, most"
58590,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.083333333,"the, that, been, to, from"
58591,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.083333333,"researchers, be, the, that, but"
58592,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.083333333,"has, origin, and, an"
58593,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.083333333,"is, an, the, by, from"
58594,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.083333333,"the, and, this, origin"
58595,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.083333333,"this, that, and, the"
58596,"Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.083333333,"other, with, sars-cov-2"
58597,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.083333333,"to, of, the, genetic"
58598,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.083333333,"other, of, coronaviruses"
58599,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.083333333,"sars-cov-2, of, and"
58600,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.083333333,"of, and, sequences, sars-cov-2"
58601,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.083333333,"of, similar, bat, sars-cov"
58602,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.083333333,"sars-cov-2, from, of, sequences, and"
58603,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.083333333,"of, and, similar, bat"
58604,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.083333333,"from, similar, sars-cov-2, of"
58605,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.083333333,"bats,, of, sars-cov-2, to"
58606,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.083333333,"the, of, its, bats,"
58607,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.083333333,"to, sars-cov-2, of, in, the"
58608,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.083333333,"the, of, animals"
58609,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.083333333,"of, these, sars-cov-2"
58610,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.083333333,"the, sars-cov-2, to, these, in, of"
58611,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.083333333,"to, of, bats,, in"
58612,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.083333333,"a, coronavirus, the, has"
58613,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.083333333,"has, that, the, coronaviruses"
58614,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.083333333,"the, coronavirus, by, a"
58615,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.083333333,"by, coronavirus, in, the"
58616,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.083333333,"a, by, in, that, the, is"
58617,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.083333333,"of, more, than, and, that, >, with"
58618,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.083333333,"to, with, the, of, and, may, subsequent"
58619,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.083333333,"in, that, the, are, more, to"
58620,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.083333333,"and, with, sars-cov-2, therefore,, to, be, in, the"
58621,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.083333333,"of, sars-cov-2, to, the, in, these"
58622,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.083333333,"the, emergence, of"
58623,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.083333333,"evidence, the, that, to"
58624,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.083333333,"of, to, the, that, this, is"
58625,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.083333333,"that, is, this"
58626,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.083333333,"the, of, is, natural, to, that"
58627,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.083333333,"and, the, be, that, of, this"
58628,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.083333333,"and, to, this, the, of, that"
58629,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.083333333,"the, sars-cov-2, pangolins"
58630,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.083333333,"its, the, that, sars-cov-2"
58631,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.083333333,"on, pangolins, or, bats, be"
58632,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.083333333,"the, and, to, that, obtained"
58633,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.083333333,"that, are, and, for"
58634,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.083333333,"are, that, sars-cov-2"
58635,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.083333333,"are, that, sars-cov-2, and"
58636,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.083333333,"and, that, bats"
58637,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.083333333,"bats, sars-cov-2, and"
58638,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.083333333,"pangolins, that, sars-cov-2"
58639,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.083333333,"that, are, sars-cov-2, for"
58640,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.083333333,"the, bats, for, genome"
58641,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.083333333,"that, the, covid-19"
58642,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.083333333,"more, likely, analysis"
58643,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.083333333,"from, to, a, found, in, china"
58644,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.083333333,"the, is, by, a, that, in"
58645,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.083333333,"a, sars-cov-2, the, bat"
58646,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.083333333,"bat, the, are, sars-cov-2"
58647,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.083333333,"which, to, that, of, and"
58648,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.083333333,"sars-cov-2, in, genome"
58649,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.083333333,"the, of, in, origin"
58650,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.083333333,"the, a, of, by, bat"
58651,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.083333333,"from, a, in, to"
58652,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.083333333,"was, in, a, of"
58653,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.083333333,"found, in, to, these, obtained"
58654,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.083333333,"to, of, from, a"
58655,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.083333333,"in, related, to, sampled"
58656,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.083333333,"have, of, to, and"
58657,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.083333333,"and, in, found, similar, to"
58658,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.083333333,"related, to, genomic, in, and"
58659,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.083333333,"in, and, et, al., found"
58660,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.083333333,"which, found, in, genome"
58661,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.083333333,"that, are, for"
58662,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.083333333,"that, an, be"
58663,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.083333333,"in, that, be, sars-cov-2"
58664,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.083333333,"sars-cov-2, that, with, for"
58665,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.083333333,"the, of, and, are, to, for, virus"
58666,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.083333333,"that, the, of, to, have, a, by"
58667,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.083333333,"the, of, similar, to, for"
58668,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.083333333,"one, of, with, sars-cov-2"
58669,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.083333333,"through, the, that, and, of"
58670,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.083333333,"the, coronavirus, and, that, a"
58671,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.083333333,"the, a, of, that, coronavirus, and"
58672,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.083333333,"by, a, of, the, sars-cov-2,, that, and"
58673,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.083333333,"the, of, domain, that, receptor"
58674,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.083333333,"coronavirus, a, and, spike, other, in, the"
58675,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.083333333,"the, sars-cov-2, we, to"
58676,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.083333333,"as, to, sars-cov-2"
58677,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.083333333,"the, sars-cov-2, been"
58678,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.083333333,"in, sequences, and"
58679,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.083333333,"sars-cov-2, a, and, that, in"
58680,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.083333333,"sars-cov-2, is, bat, to"
58681,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.083333333,"sars-cov-2, than"
58682,"Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely","B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen",0.083333333,"the, we"
58683,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.083333333,"whole, genome, the, in, and"
58684,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.083333333,"results, the, that, to"
58685,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.083333333,"to, the, in, on"
58686,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.083333333,"the, to, and, these, viruses"
58687,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.083333333,"the, and, in, that, based"
58688,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.083333333,"and, in, to, the, evidence"
58689,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.083333333,"in, for, to, be, that"
58690,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.083333333,"is, the, that, thus"
58691,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.083333333,"the, that, with, bat"
58692,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.083333333,"the, within, are, that"
58693,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.083333333,"believe, that, the, bat, same"
58694,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.083333333,"coronavirus, from, been"
58695,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.083333333,"bats, that, this, novel"
58696,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.083333333,"bats, and, the, from"
58697,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.083333333,"the, with, sars-cov-2, is, origin"
58698,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.083333333,"sars-cov-2, which, to, have, or, in, the"
58699,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.083333333,"the, which, is, to"
58700,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.083333333,"cov, with, bat, the, sars-cov-2"
58701,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.083333333,"the, is, likely, in, to, same"
58702,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.083333333,"with, bat, cov, sars-cov-2"
58703,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.083333333,"the, and, by, that, in"
58704,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.083333333,"the, that, with, sars-cov-2, as, by"
58705,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.083333333,"the, pangolin, to, with, sars-cov-2"
58706,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.083333333,"results, that, of, sars-cov-2, the, part"
58707,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.083333333,"bat, to, of, and, are, as, they"
58708,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.083333333,"by, in, the, are, with"
58709,"Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.083333333,"or, the"
58710,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.083333333,"cov, bat, the, of"
58711,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV",0.083333333,"this, or"
58712,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.083333333,"the, sars, that"
58713,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.083333333,"the, than, which, that"
58714,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.083333333,"bat, similarity, sars-cov-2"
58715,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.083333333,"the, with, that, sars-cov-2"
58716,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.083333333,"with, origin, the"
58717,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.083333333,"the, sars-cov-2, or, that"
58718,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.083333333,"the, that, same"
58719,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.083333333,"of, sars-cov-2, bats"
58720,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.083333333,"the, of, that, likely"
58721,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.083333333,"the, of, that, more, than"
58722,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.083333333,"the, of, than"
58723,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.083333333,"origin, the, and, this"
58724,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.083333333,"cluster, of, sars-cov-2, origin"
58725,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.083333333,"the, and, viruses, than"
58726,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.083333333,"the, and, clusters, but"
58727,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.083333333,"the, and, sars-cov-2, same"
58728,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.083333333,"are, the, sars-cov-2, bat"
58729,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.083333333,"origin, are, the, and"
58730,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.083333333,"bats, may"
58731,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.083333333,"this, in, that"
58732,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.083333333,"that, or, sars-cov-2, in, this"
58733,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.083333333,"sars-cov-2, that, to, the, for"
58734,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.083333333,"sars-cov-2, pangolins, and, of, as"
58735,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.083333333,"bat, the, of, from"
58736,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.083333333,"the, on, of, bat, and"
58737,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.083333333,"in, the, of, virus, from, and"
58738,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.083333333,"bat, from, in, the, virus, china, of, and"
58739,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.083333333,"the, in, of, virus"
58740,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.083333333,"of, the, suggest, origin, virus"
58741,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.083333333,"found, sars-cov-2, and, of"
58742,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.083333333,"sars-cov-2, of, various, to, a, that, the"
58743,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.083333333,"the, of, likely, a, to, that"
58744,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.083333333,"the, likely, that, of, sars-cov-2, a"
58745,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.083333333,"to, the, of, that, sars-cov-2, a"
58746,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.083333333,"sars-cov-2, to, similarity, and"
58747,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.083333333,"to, and, sars-cov-2"
58748,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.083333333,"that, with, sars-cov-2"
58749,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.083333333,"similarity, to, that"
58750,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.083333333,"with, and, to, that, sars-cov-2"
58751,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.083333333,"and, the, of, is, sars-cov-2"
58752,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.083333333,"sars-cov, sars-cov-2, of"
58753,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.083333333,"and, from, the"
58754,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.083333333,"the, and, spillover"
58755,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.083333333,"and, the, spillover"
58756,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.083333333,"and, the, for, spillover, from"
58757,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.083333333,"and, revealed, bat-sl-cov-2"
58758,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.083333333,"that, sars-cov-2, the, in"
58759,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.083333333,"that, of, and"
58760,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.083333333,"in, and, sars-cov-2, the"
58761,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.083333333,"in, between, and, for"
58762,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.083333333,"of, in, sars-cov-2"
58763,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.083333333,"from, a, in, the, and"
58764,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.083333333,"and, a, in, the"
58765,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.083333333,"the, in, and, originated, a"
58766,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.083333333,"the, have, of, and"
58767,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.083333333,"and, of, that, including"
58768,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.083333333,"more, than, sars-cov-2, with, and"
58769,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.083333333,"more, with, sars-cov-2, than, and"
58770,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.083333333,"from, humans,, bats,, and"
58771,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.083333333,"the, is, with, sars-cov-2"
58772,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.083333333,"sars-cov-2, in"
58773,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.083333333,"and, to, the, sars-cov-2, in"
58774,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.083333333,"the, that, and, this"
58775,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.083333333,"in, of, for, that"
58776,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.083333333,"the, of, it, and"
58777,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.083333333,"the, and, of, that, in, this, between, be"
58778,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.083333333,"sars-cov-2,, that, of"
58779,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.083333333,"from, to, not, bats, of"
58780,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.083333333,"not, of, the, to, from"
58781,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.083333333,"the, sars-cov-2, that, bats"
58782,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.083333333,"suggesting, sars-cov-2, the"
58783,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.083333333,"in, the, that, to, at"
58784,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.083333333,"that, sars-cov-2, to, is, in"
58785,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.083333333,"in, the, of, pangolin, that"
58786,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.083333333,"sars-cov-2, host"
58787,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.083333333,"the, sars-cov-2, for"
58788,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.083333333,"the, finding, sars-cov-2"
58789,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","This  

finding suggests the Pangolin as the intermediate host for SARS-CoV-2",0.083333333,"this, sars-cov-2, the"
58790,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.083333333,"to, sars-cov-2,, of, sars-cov-2"
58791,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.083333333,"phylogenetic, and, at, of"
58792,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.083333333,"at, with, rbd, of, and"
58793,"Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.083333333,"revealed, bat-sl-cov-2, and"
58794,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.083333333,"the, to, a, of, recombination"
58795,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.083333333,"a, to, the, of, with"
58796,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.083333333,"animal, as, in, bat"
58797,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.083333333,"the, for, that"
58798,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.083333333,"as, the, bat"
58799,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.083333333,"the, in, for, as, was, that, animal"
58800,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.083333333,"the, that, first, in"
58801,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.083333333,"that, be, sars-cov-2, to"
58802,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.083333333,"likely, to, sars-cov-2"
58803,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.083333333,"that, originated, to"
58804,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.083333333,"the, of, sars-cov-2, another"
58805,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.083333333,"the, of, might"
58806,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.083333333,"and, sars-cov-2, intermediate, be, the"
58807,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.083333333,"the, suggesting, sars-cov-2"
58808,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.083333333,"sars-cov-2, is, in, the"
58809,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.083333333,"sars-cov-2, from, animal, a, in"
58810,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.083333333,"that, human, in, from"
58811,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.083333333,"the, be, a, human"
58812,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.083333333,"the, in, a, that, animal"
58813,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.083333333,"from, in, be, that, the, sars-cov-2"
58814,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.083333333,"of, to, would, not, an, and, the"
58815,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.083333333,"and, not, the, of"
58816,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.083333333,"the, to, with, of, and"
58817,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.083333333,"the, of, and, with"
58818,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.083333333,"is, to, the, with"
58819,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.083333333,"in, of, sars-cov-2, ("
58820,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.083333333,"from, in, of"
58821,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.083333333,"in, of, sars-cov-2"
58822,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.083333333,"and, the, origin, are"
58823,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.083333333,"a, for, origin, zoonotic"
58824,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.083333333,"a, were, to, of, in"
58825,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.083333333,"recently, in, to, be"
58826,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.083333333,"to, in, that, be, for"
58827,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.083333333,"sars-cov-2, cluster, origin, of"
58828,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.083333333,"that, in, for, of"
58829,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.083333333,"a, zoonotic, origin, for"
58830,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.083333333,"several, that, to, as, natural"
58831,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.083333333,"natural, to, that, in, and"
58832,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.083333333,"of, are, as, in, a"
58833,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.083333333,"are, a, related, to, in, and"
58834,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.083333333,"the, genome, has"
58835,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.083333333,"in, at, the"
58836,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.083333333,"in, found, genome, which"
58837,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.083333333,"the, of, in, that, to"
58838,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.083333333,"sars-cov-2, was, in"
58839,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.083333333,"that, of, to, a, in, the"
58840,"S1/S2 cleavage sites of coronaviruses are frequently modi- 

fied by insertions or deletions (indels) during evolution",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.083333333,"s1/s2, cleavage, of, insertions"
58841,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.083333333,"to, that, the, of, sars-cov-2,"
58842,"In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.083333333,"in, the, of, sars-cov-2,, were"
58843,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.083333333,"coronavirus, from, the, to, sars-cov-2"
58844,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.083333333,"be, from, to, bats, of, and, are"
58845,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.083333333,"be, in, the, that, sars-cov-2, from"
58846,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.083333333,"in, is, the, be"
58847,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.083333333,"is, its, to, the"
58848,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.083333333,"to, the, coronavirus, in, of"
58849,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.083333333,"a, of, the, that, and, are, in"
58850,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.083333333,"that, the, of, to, coronaviruses"
58851,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.083333333,"to, a, in, the, ace2"
58852,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.083333333,"to, sars-cov-2,, of, a, common"
58853,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.083333333,"that, to, and, of"
58854,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.083333333,"is, and, of, in"
58855,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.083333333,"to, bat, and, that"
58856,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.083333333,"of, to, that, and, bat"
58857,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.083333333,"of, to, that, and"
58858,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.083333333,"in, to, is, of, and"
58859,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.083333333,"of, that, is, bat, possible"
58860,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.083333333,"to, of, bats,, and, in"
58861,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.083333333,"of, to, bats,, in"
58862,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.083333333,"that, of, similar, to, and"
58863,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.083333333,"that, of, including, and"
58864,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.083333333,"of, sars-cov-2, from, as"
58865,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.083333333,"including, from, and, of, sars-cov-2"
58866,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.083333333,"from, of, multiple, lineages, sars-cov-2"
58867,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.083333333,"some, coronaviruses, sars-cov-2, including, of"
58868,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.083333333,"of, coronaviruses, as, and"
58869,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.083333333,"of, and, pangolins, as, sars-cov-2"
58870,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.083333333,"the, of, that, as"
58871,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.083333333,"the, of, that, to, as"
58872,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.083333333,"to, the, s, protein"
58873,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.083333333,"that, the, of, as, to"
58874,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.083333333,"ratg13,, is, to, the"
58875,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.083333333,"virus, in, of, with, sars-cov-2"
58876,"Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.083333333,"the, rbd, sars-cov-2, in, with"
58877,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.083333333,"to, the, zoonotic, be, and, many, in, of, high, analysis"
58878,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.083333333,"on, and, to, of, in, the"
58879,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.083333333,"sars-cov-2, natural, and, in, zoonotic"
58880,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.083333333,"the, of, 96%, and"
58881,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.083333333,"sars-cov-2, the, of, domain"
58882,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.083333333,"the, sars-cov-2, to, high, of, and"
58883,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.083333333,"the, is, a, that"
58884,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.082802548,"the, and, were, in, with, by, however,, of, a, as, to, that, virus"
58885,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.082802548,"by, the, of, a, in, to, that, with, as, and, however,, were, virus"
58886,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.082758621,"the, and, in, with, of, a, which, as, to, that, infected, virus"
58887,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.082758621,"that, were, from, bats, in, the, a, or, and, of, viruses., further"
58888,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.082758621,"the, bats, were, viruses., and, a, in, of, from, that, or, further"
58889,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.082758621,"and, the, of, infected, to, as, a, with, that, in, which, virus"
58890,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.082644628,"by, the, of, a, viruses, in, that, and, progenitor, were"
58891,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.082644628,"from, the, a, that, this, and, by, in, of, at"
58892,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.082644628,"as, the, of, at, if, to, for, genetic, had, such"
58893,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.082644628,"to, such, as, at, the, if, had, of, genetic, for"
58894,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.082644628,"in, and, while, sars-cov-2, with, bat, pangolin, that, the, between"
58895,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.082644628,"a, of, the, by, that, and, in, progenitor, viruses, were"
58896,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.082644628,"a, of, the, from, this, by, that, and, at, in"
58897,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.082644628,"a, samples, on, and, were, to, specific, of, in, the"
58898,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.082644628,"in, the, of, a, to, on, samples, were, and, specific"
58899,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.082644628,"between, sars-cov-2, and, the, pangolin, in, with, while, that, bat"
58900,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.082568807,"in, the, of, as, was, to, infected, a, is"
58901,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.082568807,"with, the, of, a, to, in, is, sars-cov-2, infected"
58902,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.082568807,"a, of, in, that, for, the, or, to, virus"
58903,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.082568807,"a, in, species, to, as, and, coronaviruses, china, south"
58904,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.082568807,"from, to, a, bat, as, and, could, in, an"
58905,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.082568807,"in, a, of, the, from, positive, presence, samples,, and"
58906,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.082568807,"evidence, to, a, of, the, it, has, been, that"
58907,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.082568807,"the, by, of, receptor, that, this, coronavirus, natural, a"
58908,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.082568807,"and, the, of, to, it, can, that, sars-cov-2, is"
58909,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.082568807,"viruses, to, the, coronavirus, have, in, of, and, that"
58910,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.082568807,"the, that, to, is, of, can, it, and, sars-cov-2"
58911,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.082568807,"that, it, to, the, a, of, has, been, evidence"
58912,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.082568807,"the, to, a, that, bat, as, infect, in, of"
58913,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.082568807,"in, may, than, the, to, a, closely, related, and"
58914,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.082568807,"of, for, to, a, virus, or, that, in, the"
58915,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.082568807,"as, a, of, the, in, was, is, to, infected"
58916,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.082568807,"a, closely, related, to, in, may, than, the, and"
58917,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.082568807,"and, also, a, of, in, is, the, for, to"
58918,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.082568807,"to, a, as, and, coronaviruses, in, species, china, south"
58919,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.082568807,"in, the, positive, samples,, from, and, a, presence, of"
58920,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.082568807,"could, from, an, to, a, as, and, in, bat"
58921,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.082568807,"that, the, of, bat, in, as, infect, a, to"
58922,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.082568807,"the, of, have, a, to, in, and, market, were"
58923,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.082568807,"a, of, the, in, is, to, infected, with, sars-cov-2"
58924,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.082568807,"the, viruses, that, to, have, coronavirus, in, of, and"
58925,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.082568807,"the, market, have, in, of, were, to, and, a"
58926,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.082568807,"in, the, of, for, also, to, a, is, and"
58927,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.082568807,"receptor, that, this, the, coronavirus, by, a, of, natural"
58928,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).",0.082524272,"the, was, also, first, to, a, that, with, as, and, infect, human, by, in, of, coronavirus, known"
58929,"The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.082524272,"the, of, in, a, coronavirus, known, to, infect, and, was, that, first, with, also, human, as, by"
58930,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.082474227,"the, sars, bats, as, in, from, horseshoe, or"
58931,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.082474227,"and, a, novel, to, the, of, human, or"
58932,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.082474227,"the, has, a, of, that, to, such, and"
58933,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.082474227,"which, the, be, of, to, and, in, other"
58934,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.082474227,"the, a, in, bats,, to, that, and, virus"
58935,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.082474227,"to, the, and, of, that, identical, genome, identity"
58936,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.082474227,"the, huanan, with, at, and, market, of, cases"
58937,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.082474227,"the, to, were, in, animal, more, than, other"
58938,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.082474227,"the, of, coronavirus, is, to, human, animal, for"
58939,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.082474227,"the, of, as, a, natural, for, it, its"
58940,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.082474227,"if, in, it, is, that, the, and, sars-cov-2"
58941,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.082474227,"is, sars-cov-2, and, to, the, viruses, that, in"
58942,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.082474227,"evidence, in, the, that, of, were, to, market"
58943,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.082474227,"the, a, to, that, with, as, and, virus"
58944,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.082474227,"that, a, the, with, cases, of, in, to"
58945,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.082474227,"in, the, animals, that, virus, to, were, and"
58946,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.082474227,"the, and, to, that, were, in, more, likely"
58947,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.082474227,"the, of, with, and, cases, huanan, market, at"
58948,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.082474227,"to, human, the, animal, coronavirus, of, is, for"
58949,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.082474227,"of, to, human, a, novel, or, and, the"
58950,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.082474227,"the, to, virus, that, bat, and, sars, of"
58951,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.082474227,"the, malayan, pangolins, from, and, of, a, as"
58952,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.082474227,"by, the, of, a, bats, virus, coronaviruses, china"
58953,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.082474227,"its, it, as, the, a, of, for, natural"
58954,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.082474227,"sars-cov-2, and, bat, pangolin, high, to, the, of"
58955,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.082474227,"the, to, a, bat, as, human, of, yunnan"
58956,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.082474227,"the, of, viruses, to, that, or, similar, coronaviruses"
58957,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.082474227,"a, in, of, horseshoe, indicated, that, genome, found"
58958,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.082474227,"in, of, to, the, from, bats, and, were"
58959,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.082474227,"the, for, to, a, ace2, human, in, use"
58960,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.082474227,"the, live, and, were, in, poor, to, at"
58961,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.082474227,"the, in, to, that, and, coronaviruses, southern, china"
58962,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.082474227,"the, that, in, is, it, and, if, sars-cov-2"
58963,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.082474227,"that, the, of, cases, in, to, with, a"
58964,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.082474227,"the, that, or, for, of, in, a, by"
58965,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.082474227,"the, were, to, that, virus, in, animals, and"
58966,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.082474227,"the, sars, as, from, in, or, horseshoe, bats"
58967,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.082474227,"the, genome, of, identity, that, and, identical, to"
58968,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.082474227,"indicated, that, a, horseshoe, found, in, genome, of"
58969,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.082474227,"that, bats, the, reservoir, for, as, to, a"
58970,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.082474227,"a, the, to, that, in, bats,, virus, and"
58971,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.082474227,"bats, a, of, virus, by, the, china, coronaviruses"
58972,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.082474227,"that, the, of, viruses, similar, to, or, coronaviruses"
58973,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.082474227,"the, coronaviruses, to, that, in, southern, china, and"
58974,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.082474227,"the, of, to, it, that, bats, as, for"
58975,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.082474227,"the, that, with, scale, of, virus, and, to"
58976,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.082474227,"in, from, of, bats, were, to, and, the"
58977,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.082474227,"as, to, the, of, yunnan, a, human, bat"
58978,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.082474227,"to, a, in, the, use, human, ace2, for"
58979,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.082474227,"the, of, to, bat, that, as, for, its"
58980,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.082474227,"one, also, the, of, suggesting, to, as, an"
58981,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.082474227,"were, in, more, to, the, animal, than, other"
58982,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.082474227,"the, were, more, likely, to, that, in, and"
58983,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.082474227,"a, of, in, that, for, by, the, or"
58984,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.082474227,"that, the, of, market, in, to, were, evidence"
58985,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.082474227,"the, of, to, that, bats, as, it, for"
58986,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.082474227,"the, for, to, that, bat, as, of, its"
58987,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.082474227,"the, and, for, of, to, that, covid-19, is"
58988,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.082474227,"the, and, which, to, be, of, in, other"
58989,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.082474227,"the, of, as, a, from, malayan, pangolins, and"
58990,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.082474227,"to, were, live, and, in, poor, at, the"
58991,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.082474227,"of, has, to, a, such, that, and, the"
58992,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.082474227,"to, the, bats, as, for, a, reservoir, that"
58993,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.082474227,"the, viruses, that, to, in, is, and, sars-cov-2"
58994,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.082474227,"the, of, to, that, with, and, virus, scale"
58995,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.082474227,"an, to, as, the, one, suggesting, of, also"
58996,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.082474227,"sars-cov-2, and, of, the, to, pangolin, high, bat"
58997,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.082352941,"from, bats, in, the, or, are, viruses"
58998,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.082352941,"the, of, that, to, in, origin, covid-19"
58999,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.082352941,"the, covid-19, to, and, that, a, not"
59000,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.082352941,"the, various, that, sars-cov-2, to, a, and"
59001,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.082352941,"a, the, of, and, in, found, is"
59002,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.082352941,"and, the, be, of, sars-cov-2, in, a"
59003,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.082352941,"the, of, bat, to, a, that, is"
59004,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.082352941,"origin, of, covid-19, to, that, in, the"
59005,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.082352941,"a, in, the, by, one, zoonotic, and"
59006,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.082352941,"the, huanan, 2019,, and, market, of, to"
59007,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.082352941,"evidence, that, has, a, natural, animal, is"
59008,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.082352941,"the, genetic, of, to, its, natural, origin."
59009,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.082352941,"in, other, and, are, to, at, the"
59010,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.082352941,"and, of, in, the, for, viruses, to"
59011,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.082352941,"the, is, to, and, that, its, in"
59012,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.082352941,"that, are, the, more, of, sars-cov-2, than"
59013,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.082352941,"the, and, a, of, is, found, in"
59014,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.082352941,"in, the, of, not, to, that, a"
59015,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.082352941,"was, in, by, a, other, to, the"
59016,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.082352941,"the, that, to, in, is, its, and"
59017,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.082352941,"that, had, the, virus, animal, in, to"
59018,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.082352941,"2019,, the, huanan, market, to, and, of"
59019,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.082352941,"of, for, with, the, transmission, or, to"
59020,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.082352941,"the, to, in, of, is, sars, bats"
59021,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.082352941,"and, the, infected, to, into, in, virus"
59022,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.082352941,"that, animal, a, is, has, evidence, natural"
59023,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.082352941,"sars-cov-2, of, to, a, in, an, the"
59024,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.082352941,"the, of, are, a, bats, new, virus"
59025,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.082352941,"the, of, bat, to, as, a, contact"
59026,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.082352941,"the, of, to, similar, viruses, that, is"
59027,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.082352941,"that, the, of, in, to, not, a"
59028,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.082352941,"that, the, of, is, to, a, bat"
59029,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.082352941,"the, virus, into, in, infected, to, and"
59030,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.082352941,"bats, are, a, of, virus, the, new"
59031,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.082352941,"as, to, the, of, a, contact, bat"
59032,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.082352941,"is, that, the, of, viruses, similar, to"
59033,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.082352941,"in, the, and, at, are, to, other"
59034,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.082352941,"the, in, was, to, a, by, other"
59035,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.082352941,"that, the, natural, reservoir, of, in, for"
59036,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.082352941,"the, a, of, that, likely, to, by"
59037,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.082352941,"the, to, or, with, of, for, transmission"
59038,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.082352941,"evidence, that, the, of, and, in, for"
59039,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.082352941,"the, and, by, a, zoonotic, one, in"
59040,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.082352941,"the, are, from, viruses, in, or, bats"
59041,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.082352941,"this, suggests, that, in, and, the, of"
59042,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.082352941,"the, of, sars, in, is, to, bats"
59043,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.082352941,"for, and, that, in, the, emergence, of"
59044,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.082352941,"a, its, with, on, to, the, for"
59045,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.082352941,"is, a, that, with, to, the, for"
59046,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.082352941,"a, and, with, other, to, in, the"
59047,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.082352941,"the, sars-cov-2, and, be, a, of, in"
59048,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.082352941,"on, the, of, in, and, that, through"
59049,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.082352941,"for, with, to, the, its, on, a"
59050,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.082352941,"the, is, that, for, to, with, a"
59051,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.082352941,"covid-19, to, a, that, not, and, the"
59052,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.082352941,"the, of, for, natural, reservoir, in, that"
59053,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.082352941,"the, of, by, likely, a, to, that"
59054,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.082352941,"sars-cov-2, be, the, and, with, to, in"
59055,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.082352941,"its, to, the, of, genetic, natural, origin."
59056,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.082352941,"sars-cov-2, various, to, a, that, and, the"
59057,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.082352941,"on, in, the, and, that, of, through"
59058,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.082352941,"are, of, and, to, that, in, as"
59059,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.082352941,"the, that, are, more, than, of, sars-cov-2"
59060,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.082352941,"the, in, for, of, emergence, that, and"
59061,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.082352941,"this, suggests, that, in, the, and, of"
59062,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.082352941,"in, and, to, that, of, are, as"
59063,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.082352941,"in, the, of, a, that, to, and"
59064,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.082352941,"and, with, sars-cov-2, to, be, in, the"
59065,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.082191781,"that, of, made, have, a, by"
59066,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.082191781,"that, sars-cov-2, by, be, of, origin"
59067,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.082191781,"the, of, in, various, has, for"
59068,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.082191781,"bat, the, of, sars-cov-2, and, genetic"
59069,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.082191781,"the, by, in, that, a, laboratory"
59070,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.082191781,"that, the, sars-cov-2, to, with, natural"
59071,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.082191781,"the, and, to, that, sars-cov-2, of"
59072,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.082191781,"is, an, a, the, in, receptor"
59073,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.082191781,"from, and, intermediate, hosts, to, the"
59074,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.082191781,"that, sars-, cov-2, to, with, sars-cov-2"
59075,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.082191781,"from, a, in, the, which, that"
59076,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.082191781,"in, two, of, and, which, genomic"
59077,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.082191781,"the, of, market, was, a, by"
59078,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.082191781,"more, than, the, to, these, in"
59079,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.082191781,"that, than, the, sars-cov-2, in, and"
59080,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.082191781,"the, of, indicated, in, a, and"
59081,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.082191781,"a, from, market, in, the, of"
59082,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.082191781,"the, and, a, in, of, but"
59083,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.082191781,"the, of, that, a, in, to"
59084,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.082191781,"and, that, in, viruses, are, to"
59085,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.082191781,"that, viruses, in, cells, and, to"
59086,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.082191781,"from, to, not, and, are, if"
59087,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.082191781,"from, was, in, that, is, to"
59088,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.082191781,"and, in, to, that, are, not"
59089,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.082191781,"are, and, the, virus, to, in"
59090,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.082191781,"the, more, to, virus, in, and"
59091,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.082191781,"of, the, are, as, in, viruses"
59092,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.082191781,"sars-cov-2, is, a, and, to, that"
59093,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.082191781,"that, a, made, of, have, by"
59094,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.082191781,"of, a, the, market, was, by"
59095,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.082191781,"the, was, to, a, market, in"
59096,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.082191781,"the, were, to, that, in, animals"
59097,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.082191781,"the, that, of, not, by, a"
59098,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.082191781,"et, al., in, the, to, of"
59099,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.082191781,"the, and, also, in, to, of"
59100,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.082191781,"of, the, and, with, to, virus"
59101,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.082191781,"in, the, and, are, to, virus"
59102,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.082191781,"the, market, in, was, to, a"
59103,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.082191781,"of, covid-19, to, and, the, in"
59104,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.082191781,"in, the, and, to, more, virus"
59105,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.082191781,"that, the, in, to, animals, were"
59106,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.082191781,"and, to, the, in, its, animal"
59107,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.082191781,"the, of, study, a, human, and"
59108,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.082191781,"a, bat, of, and, as, on"
59109,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.082191781,"and, to, that, the, is, sars-cov-2"
59110,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.082191781,"the, sars-cov-2, and, of, genetic, bat"
59111,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.082191781,"as, in, the, of, are, viruses"
59112,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.082191781,"and, that, of, to, between, through"
59113,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.082191781,"in, different, and, with, the, between"
59114,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.082191781,"a, of, the, between, and, with"
59115,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.082191781,"the, a, in, that, these, of"
59116,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.082191781,"coronaviruses, to, in, the, that, of"
59117,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.082191781,"that, a, sars-cov-2, and, is, to"
59118,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.082191781,"sars-cov, and, a, the, of, as"
59119,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.082191781,"the, as, a, of, that, and"
59120,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.082191781,"a, of, that, the, to, virus"
59121,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.082191781,"in, with, and, similar, at, the"
59122,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.082191781,"zhang, and, of, in, an, the"
59123,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.082191781,"the, of, in, a, to, yunnan"
59124,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.082191781,"the, of, from, a, in, to"
59125,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.082191781,"the, of, a, in, and, was"
59126,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.082191781,"of, has, for, various, in, the"
59127,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.082191781,"for, were, that, found, this, to"
59128,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.082191781,"sars-cov, genetically, to, this, for, that"
59129,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.082191781,"the, is, that, in, to, not"
59130,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.082191781,"that, sars-cov-2, with, sars-, cov-2, to"
59131,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.082191781,"that, the, of, not, a, by"
59132,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.082191781,"to, from, in, bats, the, and"
59133,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.082191781,"sars-cov-2, of, and, that, the, as"
59134,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.082191781,"it, the, and, to, that, these"
59135,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.082191781,"as, and, the, of, that, sars-cov-2"
59136,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.082191781,"to, the, in, and, that, key"
59137,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.082191781,"these, and, the, to, it, that"
59138,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.082191781,"found, in, are, to, that, and"
59139,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.082191781,"an, from, to, the, team, a"
59140,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.082191781,"a, of, to, the, that, was"
59141,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.082191781,"the, of, a, to, additional, that"
59142,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.082191781,"and, the, that, was, of, a"
59143,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.082191781,"cases, the, huanan, seafood, of, in"
59144,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.082191781,"that, sars-cov-2, from, a, the, in"
59145,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.082191781,"and, the, likely, or, of, in"
59146,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.082191781,"viruses, to, and, have, the, which"
59147,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.082191781,"of, a, to, that, in, as"
59148,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.082191781,"in, the, and, with, similar, at"
59149,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.082191781,"the, other, by, in, and, a"
59150,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.082191781,"the, to, in, of, a, yunnan"
59151,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.082191781,"that, the, of, a, to, additional"
59152,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.082191781,"of, to, a, found, in, yunnan"
59153,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.082191781,"the, to, have, and, which, viruses"
59154,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.082191781,"a, between, and, with, the, of"
59155,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.082191781,"the, that, virus, to, a, of"
59156,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.082191781,"the, market, of, suggesting, a, to"
59157,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.082191781,"to, in, the, with, or, guangdong"
59158,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.082191781,"the, to, in, from, of, a"
59159,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.082191781,"were, found, to, that, for, this"
59160,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.082191781,"intermediate, and, the, from, or, in"
59161,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.082191781,"with, the, of, humans, that, or"
59162,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.082191781,"to, that, when, the, virus, of"
59163,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.082191781,"the, to, and, its, in, animal"
59164,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.082191781,"the, team, a, from, an, to"
59165,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.082191781,"in, to, of, the, covid-19, and"
59166,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.082191781,"a, of, with, to, and, the"
59167,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.082191781,"a, the, of, and, in, to"
59168,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.082191781,"a, of, market, the, suggesting, to"
59169,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.082191781,"and, also, with, many, are, known"
59170,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.082191781,"of, the, cases, in, huanan, seafood"
59171,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.082191781,"the, likely, or, of, in, and"
59172,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.082191781,"on, the, of, and, that, to"
59173,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.082191781,"between, and, that, of, to, through"
59174,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.082191781,"a, the, from, that, in, which"
59175,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.082191781,"the, of, coronaviruses, that, in, to"
59176,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.082191781,"the, of, that, spike, in, to"
59177,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.082191781,"in, the, a, that, to, and"
59178,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.082191781,"in, the, and, a, indicated, of"
59179,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.082191781,"that, to, cells, and, viruses, in"
59180,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.082191781,"a, study, the, of, and, human"
59181,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.082191781,"to, in, the, that, spike, of"
59182,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.082191781,"the, of, to, in, and, virus"
59183,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.082191781,"in, a, of, and, that, the"
59184,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.082191781,"that, and, to, the, key, in"
59185,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.082191781,"be, of, and, with, to, in"
59186,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.082191781,"are, not, if, to, from, and"
59187,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.082191781,"a, on, as, of, bat, and"
59188,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.082191781,"many, known, are, with, and, also"
59189,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.082191781,"the, virus, in, and, to, of"
59190,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.082191781,"a, of, at, the, in, china"
59191,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.082191781,"the, and, intermediate, from, in, or"
59192,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.082191781,"a, of, the, also, have, to"
59193,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.082191781,"that, the, of, and, as, a"
59194,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.082191781,"from, intermediate, hosts, to, and, the"
59195,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.082191781,"the, of, that, a, are, to"
59196,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.082191781,"a, of, also, have, the, to"
59197,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.082191781,"the, of, that, or, humans, with"
59198,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.082191781,"to, genetically, sars-cov, that, for, this"
59199,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.082191781,"of, to, a, was, from, in"
59200,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.082191781,"the, also, that, these, are, of"
59201,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.082191781,"and, sars-cov-2, has, to, in, the"
59202,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.082191781,"in, and, sars-cov-2, the, origin, is"
59203,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.082191781,"a, the, is, in, receptor, an"
59204,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.082191781,"found, in, and, are, to, that"
59205,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.082191781,"be, that, origin, of, sars-cov-2, by"
59206,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.082191781,"these, in, more, to, the, than"
59207,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.082191781,"the, and, that, from, a, to"
59208,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.082191781,"and, the, that, sars-cov-2, from, a"
59209,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.082191781,"in, the, market, from, a, of"
59210,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.082191781,"that, was, to, from, is, in"
59211,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.082191781,"the, of, china, a, in, at"
59212,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.082191781,"of, in, found, a, to, yunnan"
59213,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.082191781,"from, to, was, of, in, a"
59214,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.082191781,"zhang, in, the, of, and, an"
59215,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.082191781,"of, genomic, and, two, in, which"
59216,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.082191781,"and, in, found, to, related, of"
59217,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.082191781,"of, with, a, to, and, the"
59218,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.082191781,"that, a, laboratory, by, the, in"
59219,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.082191781,"in, by, a, other, and, the"
59220,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.082191781,"the, in, different, with, between, and"
59221,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.082191781,"and, in, the, sars-cov-2, origin, is"
59222,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.082191781,"in, cluster, sars-cov-2, with, origin, that"
59223,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.082191781,"in, guangdong, with, the, or, to"
59224,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.082191781,"a, of, that, with, the, to"
59225,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.082191781,"the, of, when, that, virus, to"
59226,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.082191781,"in, the, a, that, from, human"
59227,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.082191781,"in, sars-cov-2, with, cluster, that, origin"
59228,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.082191781,"that, of, in, as, a, to"
59229,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.082191781,"in, found, related, of, and, to"
59230,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.082191781,"in, the, but, and, a, of"
59231,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.082191781,"are, that, not, to, and, in"
59232,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.082191781,"also, the, of, and, in, to"
59233,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.082191781,"in, the, of, a, that, these"
59234,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.082191781,"the, that, these, are, also, of"
59235,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.082191781,"the, virus, of, to, with, and"
59236,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.082191781,"to, be, with, of, and, in"
59237,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.082089552,"the, live, were, in, covered, by, of, a, to, we, that"
59238,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.082089552,"the, in, for, researchers, of, identified, were, to, and, a, had"
59239,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.082089552,"in, these, viruses, and, with, bat, this, that, the, same, sars"
59240,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.082089552,"in, a, of, researchers, to, the, for, identified, and, had, were"
59241,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.082089552,"that, the, of, in, covered, to, live, were, we, a, by"
59242,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.082089552,"in, the, same, bat, with, these, viruses, and, that, sars, this"
59243,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.081967213,"the, of, asia, and, southeast"
59244,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.081967213,"the, of, and, that, virus,"
59245,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.081967213,"in, the, from, and, evolved"
59246,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.081967213,"from, pangolins, in, the, of"
59247,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.081967213,"and, of, that, in, southeast"
59248,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.081967213,"are, sarbecoviruses,, and, viruses, in"
59249,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.081967213,"bats, are, as, the, in"
59250,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.081967213,"of, and, the, asia, southeast"
59251,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.081967213,"animals, that, virus, for, and"
59252,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.081967213,"revealed, and, with, of, virus"
59253,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.081967213,"bats, of, and, in, to"
59254,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.081967213,"its, such, to, sars-cov-2, in"
59255,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.081967213,"the, spillover, to, of, and"
59256,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.081967213,"of, human, and, which, with"
59257,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.081967213,"the, in, to, infected, a"
59258,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.081967213,"the, of, is, to, used"
59259,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.081967213,"is, it, of, sars-cov-2, to"
59260,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.081967213,"in, to, the, sars-cov-2, as"
59261,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.081967213,"to, of, it, is, in"
59262,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.081967213,"sars-cov-2, a, of, been, that"
59263,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.081967213,"by, of, that, coronavirus, a"
59264,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.081967213,"and, have, the, bat, of"
59265,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.081967213,"genetic, the, in, a, to"
59266,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.081967213,"of, the, and, other, bat"
59267,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.081967213,"by, virus, the, was, in"
59268,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.081967213,"the, a, because, its, from"
59269,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.081967213,"in, the, sars-cov-2, also, from"
59270,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.081967213,"the, by, was, from, a"
59271,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.081967213,"is, highly, that, exist, in"
59272,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.081967213,"the, of, to, and, a"
59273,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.081967213,"to, sars-cov-2, the, that, with"
59274,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.081967213,"that, was, sars-cov-2, to, and"
59275,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.081967213,"that, in, were, as, of"
59276,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.081967213,"in, of, more, that, and"
59277,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.081967213,"and, of, in, receptor, which"
59278,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.081967213,"that, the, of, can, to"
59279,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.081967213,"been, the, and, are, have"
59280,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.081967213,"the, as, are, in, bats"
59281,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.081967213,"the, into, to, of, and"
59282,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.081967213,"a, and, in, an, host"
59283,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.081967213,"is, that, a, host, to"
59284,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.081967213,"from, to, bats, of, as"
59285,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.081967213,"from, the, to, of, bats"
59286,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.081967213,"in, of, and, the, as"
59287,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.081967213,"animals, and, that, for, virus"
59288,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.081967213,"animals, to, the, virus, and"
59289,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.081967213,"the, which, to, is, in"
59290,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.081967213,"the, over, from, to, rhinolophus"
59291,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.081967213,"the, of, and, to, into"
59292,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.081967213,"in, the, was, to, and"
59293,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.081967213,"the, animals, that, with, at"
59294,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.081967213,"the, to, for, humans, and"
59295,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.081967213,"yet, to, the, of, evidence"
59296,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.081967213,"a, the, it, been, that"
59297,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.081967213,"on, that, with, sars-cov-2, at"
59298,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.081967213,"a, sars-cov-2, and, to, host"
59299,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.081967213,"in, found, and, have, to"
59300,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.081967213,"sars-cov-2, of, natural, the, to"
59301,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.081967213,"are, natural, and, that, such"
59302,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.081967213,"the, and, have, of, bat"
59303,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.081967213,"that, the, of, and, have"
59304,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.081967213,"from, closely, related, of, bats"
59305,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.081967213,"the, of, most, at, huanan"
59306,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.081967213,"and, the, into, sars-cov-2, with"
59307,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.081967213,"in, of, sars-cov-2, with, that"
59308,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.081967213,"of, the, and, with, in"
59309,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.081967213,"and, hosts, other, the, in"
59310,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.081967213,"in, the, and, at, huanan"
59311,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.081967213,"sars-cov-2, in, the, and, that"
59312,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.081967213,"sars-cov-2, and, to, of, in"
59313,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.081967213,"of, and, two, in, least"
59314,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.081967213,"of, from, to, humans, and"
59315,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","All U.S. intel- 

ligence agencies rejected the alle- 

gation that participants in a clan- 

destine Chinese biologic weapons  

program intentionally developed  

SARS-CoV-2",0.081967213,"sars-cov-2, a, in, the, that"
59316,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.081967213,"of, sars-cov-2, from, the, animals"
59317,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.081967213,"the, cases, animals, that, sars-cov-2"
59318,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.081967213,"was, to, and, that, sars-cov-2"
59319,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.081967213,"sars-cov-2, to, it, is, and"
59320,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.081967213,"is, in, wiv, a, that"
59321,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.081967213,"that, a, in, evidence, or"
59322,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.081967213,"that, or, sars-cov-2, in, a"
59323,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.081967213,"had, that, sars-cov-2, in, a"
59324,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.081967213,"the, that, animals, at, with"
59325,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.081967213,"that, sars-cov-2, with, on, at"
59326,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.081967213,"cases, the, that, sars-cov-2, animals"
59327,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.081967213,"the, to, a, genetic, in"
59328,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.081967213,"evidence, that, the, two, in"
59329,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.081967213,"we, have, to, as, the"
59330,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.081967213,"that, is, likely, to, from"
59331,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.081967213,"covid-19, a, to, wuhan, in"
59332,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.081967213,"the, to, evidence, of, yet"
59333,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.081967213,"on, and, with, to, a"
59334,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.081967213,"and, a, to, that, as"
59335,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.081967213,"and, which, that, in, human"
59336,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.081967213,"covid-19, a, to, and, the"
59337,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.081967213,"in, of, that, the, or"
59338,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.081967213,"that, to, than, the, in"
59339,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.081967213,"been, in, the, to, that"
59340,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.081967213,"the, of, to, also, and"
59341,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.081967213,"of, the, in, their, and"
59342,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.081967213,"also, the, of, to, as"
59343,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.081967213,"sars-cov-2, and, from, can, to"
59344,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.081967213,"similar, to, the, of, and"
59345,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.081967213,"of, the, bat, and, pangolin"
59346,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.081967213,"of, and, that, the, virus,"
59347,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.081967213,"was, that, the, have, of"
59348,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.081967213,"a, the, in, to, infected"
59349,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.081967213,"the, of, most, individuals, exposure"
59350,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.081967213,"animals, virus, to, and, the"
59351,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.081967213,"of, are, and, which, in"
59352,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.081967213,"and, the, but, they, are"
59353,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.081967213,"evidence, the, that, of, all"
59354,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.081967213,"the, in, and, that, natural"
59355,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.081967213,"the, animal, to, and, reservoirs"
59356,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Huanan Seafood Wholesale Market, in Wuhan,  

Hubei, China.1 

 The initial outbreak was reported in the mar- 

ket in December 2019 and involved about 66% of the staff  

there.",0.081967213,"was, seafood, in, the, of"
59357,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.081967213,"the, and, that, of, to"
59358,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.081967213,"bat, is, the, with, for"
59359,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.081967213,"study, with, the, of, as"
59360,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.081967213,"that, of, were, in, as"
59361,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.081967213,"the, of, have, that, was"
59362,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.081967213,"the, of, that, host,, but"
59363,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.081967213,"to, the, of, coronavirus, sars-cov-2"
59364,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.081967213,"sars-cov-2, host, to, a, and"
59365,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.081967213,"that, the, same, a, to"
59366,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.081967213,"of, the, is, used, to"
59367,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.081967213,"to, more, than, the, bat"
59368,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.081967213,"bats, found, to, sars-cov, for"
59369,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.081967213,"the, or, of, bats, and"
59370,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.081967213,"to, as, which, at, the"
59371,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.081967213,"with, the, of, could, or"
59372,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.081967213,"of, to, which, was, found"
59373,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.081967213,"the, of, that, from, human"
59374,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.081967213,"the, is, sequence, that, beta"
59375,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.081967213,"to, that, sars-cov-2, may, have"
59376,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.081967213,"from, a, of, in, the"
59377,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.081967213,"of, sars-cov, and, bat, that"
59378,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.081967213,"bat, bats, of, and, on"
59379,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.081967213,"by, that, is, of, bats"
59380,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.081967213,"a, that, animal, to, virus"
59381,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.081967213,"isolated, from, sars-cov-2, to, the"
59382,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.081967213,"are, all, sars-cov-2, bat, the"
59383,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.081967213,"in, the, to, is, of"
59384,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.081967213,"of, it, is, to, sars-cov-2"
59385,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.081967213,"it, by, and, to, sars-cov-2"
59386,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.081967213,"there, to, more, sars-cov-2, and"
59387,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.081967213,"the, and, of, other, bat"
59388,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.081967213,"and, the, coronavirus, of, with"
59389,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.081967213,"of, the, in, was, with"
59390,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.081967213,"was, by, the, virus, in"
59391,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.081967213,"and, of, in, the, human"
59392,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.081967213,"of, virus, with, and, the"
59393,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.081967213,"viruses, are, and, that, the"
59394,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.081967213,"of, bats,, and, for, with"
59395,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.081967213,"with, of, and, which, human"
59396,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.081967213,"are, in, of, which, and"
59397,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.081967213,"with, of, bats,, and, in"
59398,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.081967213,"of, with, and, are, for"
59399,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.081967213,"the, to, of, and, coronavirus"
59400,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.081967213,"of, the, and, with, coronavirus"
59401,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.081967213,"the, of, coronaviruses, and, with"
59402,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.081967213,"to, the, with, or, pangolin"
59403,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.081967213,"of, the, and, approximately, with"
59404,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.081967213,"related, of, genome, and, to"
59405,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.081967213,"of, and, revealed, virus, with"
59406,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.081967213,"the, of, from, a, these"
59407,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.081967213,"of, the, isolated, in, from"
59408,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.081967213,"of, with, a, and, the"
59409,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.081967213,"and, that, sars-cov, of, bat"
59410,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.081967213,"ratg13, s, the, sequence, of"
59411,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.081967213,"intermediate, hosts, to, be, the"
59412,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.081967213,"the, that, from, animals, for"
59413,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.081967213,"the, from, of, sars-cov-2, animals"
59414,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.081967213,"the, of, from, that, for"
59415,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.081967213,"sars-cov-2, the, that, for, of"
59416,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.081967213,"to, from, and, can, sars-cov-2"
59417,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.081967213,"that, in, bats, and, to"
59418,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.081967213,"et, a, bat, sars-cov-2, in"
59419,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.081967213,"of, sequences, similarity, a, which"
59420,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.081967213,"of, the, host,, that, but"
59421,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.081967213,"a, of, the, that, with"
59422,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.081967213,"a, the, of, results, that"
59423,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.081967213,"the, of, host, that, a"
59424,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.081967213,"the, be, that, of, a"
59425,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.081967213,"the, of, that, may, a"
59426,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.081967213,"the, most, of, at, huanan"
59427,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.081967213,"the, at, huanan, in, and"
59428,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.081967213,"individuals, the, of, exposure, most"
59429,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.081967213,"of, most, similar, the, and"
59430,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.081967213,"at, found, in, the, with"
59431,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.081967213,"that, transmission, of, to, the"
59432,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.081967213,"the, of, that, could, to"
59433,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.081967213,"be, transmission, to, only, of"
59434,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.081967213,"only, of, the, to, 2020,"
59435,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.081967213,"seafood, that, the, to, of"
59436,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.081967213,"the, to, suggesting, that, of"
59437,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.081967213,"in, that, of, on, and"
59438,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.081967213,"the, of, for, natural, in"
59439,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.081967213,"for, the, of, been, in"
59440,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.081967213,"the, that, of, in, but"
59441,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.081967213,"to, of, the, which, and"
59442,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.081967213,"from, a, because, the, its"
59443,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.081967213,"host, of, and, the, bats"
59444,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.081967213,"in, sars-cov-2, with, cov, the"
59445,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.081967213,"in, the, and, that, of, positive, were, linked, to, between"
59446,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.081967213,"contact, to, a, may, be"
59447,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.081967213,"of, a, to, as, human"
59448,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.081967213,"and, that, of, in, more"
59449,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.081967213,"of, to, the, that, transmission"
59450,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.081967213,"the, of, homology, with, sars-cov-2"
59451,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.081967213,"the, in, that, bats, sars-cov-2"
59452,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.081967213,"that, the, sars-cov-2, pangolin, is"
59453,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.081967213,"coronaviruses, and, the, of, with"
59454,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.081967213,"the, of, from, rhinolophus, and"
59455,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.081967213,"the, by, of, that, a"
59456,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.081967213,"the, of, is, and, that"
59457,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.081967213,"and, the, evolved, from, in"
59458,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.081967213,"as, the, in, to, sars-cov-2"
59459,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.081967213,"also, sars-cov-2, from, the, in"
59460,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.081967213,"from, to, bats, of, and"
59461,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.081967213,"2, and, with, bat, the"
59462,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.081967213,"the, of, s, sequence, ratg13"
59463,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.081967213,"of, homology, with, sars-cov-2, the"
59464,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.081967213,"the, rbd, region, has, of"
59465,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.081967213,"the, by, sequence, in, coronaviruses"
59466,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).",0.081967213,"et, reported, that, the, sars-cov-2, to, these, by, with, in, insertion, appears, of, natural, and"
59467,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.081967213,"and, similar, by, in, the"
59468,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.081967213,"that, such, as, to, sars-cov-2"
59469,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.081967213,"of, the, in, that, or"
59470,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.081967213,"other, and, in, the, hosts"
59471,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.081967213,"to, the, than, in, that"
59472,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.081967213,"are, the, have, been, and"
59473,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.081967213,"to, the, in, that, been"
59474,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.081967213,"that, found, through, to, the"
59475,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.081967213,"in, the, to, that, bind"
59476,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.081967213,"to, sars-cov-2, could, a, the"
59477,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.081967213,"the, to, humans, and, for"
59478,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.081967213,"it, sars-cov-2, to, and, is"
59479,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.081967213,"also, the, of, and, to"
59480,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.081967213,"of, the, also, by, to"
59481,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.081967213,"in, the, and, to, sars-cov-2"
59482,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.081967213,"the, of, that, sequences, in"
59483,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.081967213,"a, that, the, it, been"
59484,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.081967213,"a, the, could, to, sars-cov-2"
59485,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.081967213,"the, from, and, in, with, extensive, of, a, to, that"
59486,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.081967213,"in, rhinolophus, has, the, with"
59487,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.081967213,"is, it, that, of, sars-cov-2"
59488,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.081967213,"the, from, a, at, of"
59489,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.081967213,"of, it, is, highly, that"
59490,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.081967213,"bats, the, or, of, and"
59491,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.081967213,"the, to, and, animal, reservoirs"
59492,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.081967213,"as, and, for, the, of"
59493,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.081967213,"the, and, in, similar, by"
59494,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.081967213,"the, of, can, to, that"
59495,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.081967213,"a, that, the, same, to"
59496,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.081967213,"the, that, a, in, covid-19"
59497,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.081967213,"as, the, to, at, which"
59498,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.081967213,"and, it, sars-cov-2, to, by"
59499,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.081967213,"to, a, in, and, level"
59500,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.081967213,"is, that, wiv, a, in"
59501,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.081967213,"from, in, the, of, is"
59502,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.081967213,"a, the, and, is, to"
59503,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2",0.081967213,"and, amino, acid, sars-cov-2, the"
59504,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.081967213,"in, to, human, and, a"
59505,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.081967213,"in, a, and, to, level"
59506,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.081967213,"a, to, in, these, and"
59507,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.081967213,"and, a, in, to, human"
59508,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.081967213,"as, the, of, to, is"
59509,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.081967213,"in, the, to, sars-cov-2, is"
59510,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.081967213,"the, more, than, to, bat"
59511,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.081967213,"there, and, more, sars-cov-2, to"
59512,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.081967213,"to, a, in, and, these"
59513,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.081967213,"the, a, and, to, with"
59514,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.081967213,"to, and, related, in, bat"
59515,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.081967213,"a, the, with, that, of"
59516,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.081967213,"was, from, a, by, the"
59517,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.081967213,"a, the, of, at, from"
59518,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.081967213,"a, to, with, the, and"
59519,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.081967213,"virus, that, animal, to, a"
59520,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.081967213,"evidence, that, or, a, in"
59521,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.081967213,"that, the, of, human, from"
59522,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.081967213,"a, virus, the, and, an"
59523,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.081967213,"isolated, from, a, and, identity, reservoirs, to, be, in, the"
59524,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.081967213,"of, that, the, bat, a, from, thus, these, species, as"
59525,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.081967213,"that, by, a, recombination, of, with, similar, to, and, the"
59526,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.081967213,"covid-19, in, wuhan, a, to"
59527,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.081967213,"a, which, on, the, in"
59528,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.081967213,"to, on, the, in, and"
59529,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.081967213,"in, the, of, that, but"
59530,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.081967213,"is, in, the, that, human"
59531,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.081967213,"in, of, sequences, and, genomic"
59532,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.081967213,"that, sars-cov-2, likely, be, from"
59533,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.081967213,"between, and, of, the, linked, to, in, were, that, positive"
59534,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.081967213,"found, the, to, that, through"
59535,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.081967213,"the, of, human, to, a"
59536,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.081967213,"is, to, the, that, this"
59537,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.081967213,"a, of, it, that, is"
59538,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.081967213,"it, that, of, sars-cov-2, a"
59539,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.081967213,"the, that, is, sars-, cov-2"
59540,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.081967213,"from, that, the, sars-, is"
59541,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.081967213,"the, is, that, human, in"
59542,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.081967213,"the, is, a, that, in"
59543,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.081967213,"a, of, the, humans,, through"
59544,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.081967213,"the, of, a, from, these"
59545,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.081967213,"that, of, and, the, sars-cov-2"
59546,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.081967213,"that, the, covid-19, in, a"
59547,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.081967213,"of, could, to, the, that"
59548,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.081967213,"bats, of, and, to, in"
59549,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.081967213,"a, the, of, from, bat"
59550,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.081967213,"the, of, a, bat, as, these, that, thus, from, species"
59551,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.081967213,"the, evidence, of, origin, is"
59552,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.081967213,"is, origin, the, that, from"
59553,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.081967213,"a, of, for, origin, that"
59554,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.081967213,"and, to, that, in, bats"
59555,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.081967213,"the, china, to, in, market"
59556,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.081967213,"the, of, and, similar, most"
59557,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.081967213,"to, the, key, of, a"
59558,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.081967213,"and, are, in, sarbecoviruses,, viruses"
59559,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.081967213,"and, that, have, the, of"
59560,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.081967213,"least, two, of, in, and"
59561,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.081967213,"evidence, the, that, in, two"
59562,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.081967213,"to, that, the, of, have"
59563,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.081967213,"of, bats, a, in, the"
59564,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.081967213,"a, bats, diversity, of, as"
59565,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.081967213,"the, a, in, these, of"
59566,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.081967213,"in, all, bat, the, is"
59567,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.081967213,"the, of, bats, host, and"
59568,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.081967213,"and, of, viruses, in, bat"
59569,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.081967213,"of, and, in, with, bats,"
59570,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.081967213,"and, in, their, to, of"
59571,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.081967213,"in, of, to, be, with"
59572,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.081967213,"the, from, humans, to, and"
59573,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.081967213,"to, of, from, bats, as"
59574,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.081967213,"on, and, bats, of, bat"
59575,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.081967213,"only, of, be, to, transmission"
59576,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.081967213,"from, of, bats, to, and"
59577,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.081967213,"a, diversity, of, bats, as"
59578,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.081967213,"on, a, with, and, to"
59579,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.081967213,"to, may, be, a, contact"
59580,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.081967213,"the, to, in, market, china"
59581,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.081967213,"the, of, and, their, in"
59582,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.081967213,"sars-cov-2, in, the, is, of"
59583,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.081967213,"of, the, been, have, origin"
59584,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.081967213,"of, the, from, in, pangolins"
59585,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.081967213,"to, from, a, of, in, the, extensive, and, that, with"
59586,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.081967213,"a, which, related, to, covs"
59587,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.081967213,"2020,, only, of, to, the"
59588,"r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.081967213,"a, of, humans,, the, through"
59589,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.081967213,"of, the, 3, and, a"
59590,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.081967213,"the, to, rhinolophus, from, over"
59591,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.081967213,"of, humans, from, and, to"
59592,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.081967213,"sars-cov-2, and, a, bat, human"
59593,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.081967213,"to, be, the, hosts, intermediate"
59594,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.081967213,"the, and, amino, acid, sars-cov-2"
59595,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.081967213,"to, the, reservoirs, be, and, a, in, from, isolated, identity"
59596,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.081967213,"the, sars-cov-2, showed, identity, with"
59597,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.081967213,"a, of, the, that, sars-cov-2"
59598,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.081967213,"the, of, to, also, by"
59599,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.081967213,"of, the, have, been, origin"
59600,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.081967213,"a, is, that, to, host"
59601,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.081967213,"the, or, with, of, could"
59602,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.081967213,"such, as, to, that, sars-cov-2"
59603,"One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.081967213,"such, to, sars-cov-2, in, its"
59604,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.081967213,"that, had, sars-cov-2, a, in"
59605,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.081967213,"the, of, in, been, for"
59606,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.081967213,"such, that, sars-cov-2, to, from"
59607,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.081967213,"a, of, the, and, has"
59608,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.081967213,"the, has, of, to, and"
59609,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.081967213,"of, evidence, the, is, origin"
59610,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.081967213,"a, on, which, in, the"
59611,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.081967213,"in, and, on, that, of"
59612,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.081967213,"the, to, is, that, this"
59613,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.081967213,"that, the, is, origin, from"
59614,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.081967213,"sars-cov-2, of, and, similar, tion"
59615,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.081967213,"the, beta, sequence, is, that"
59616,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.081967213,"the, in, sequence, coronaviruses, by"
59617,"The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.081967213,"the, of, in, natural, et, to, these, and, sars-cov-2, that, appears, with, reported, by, insertion"
59618,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.081967213,"that, is, by, bats, of"
59619,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.081967213,"of, to, the, seafood, that"
59620,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.081967213,"using, the, in, that, bats"
59621,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.081967213,"sars-cov-2, a, bat, et, in"
59622,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.081967213,"was, found, to, which, of"
59623,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.081967213,"similarity, sequences, of, which, a"
59624,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.081967213,"and, of, receptor, in, which"
59625,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.081967213,"human, and, the, in, of"
59626,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.081967213,"have, to, and, found, in"
59627,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.081967213,"genome, of, to, and, related"
59628,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.081967213,"of, and, genomic, sequences, in"
59629,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.081967213,"of, are, and, for, with"
59630,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.081967213,"the, of, a, to, by, with, similar, and, that, recombination"
59631,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.081967213,"that, a, of, by, coronavirus"
59632,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.081967213,"a, that, the, by, other"
59633,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.081967213,"to, have, the, we, as"
59634,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.081967213,"a, of, and, the, 3"
59635,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.081967213,"on, and, to, in, the"
59636,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.081967213,"for, the, bat, is, with"
59637,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.081967213,"sars-cov-2, with, the, cov, in"
59638,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.081967213,"the, is, bat, all, in"
59639,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.081967213,"that, bats, in, sars-cov-2, the"
59640,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.081967213,"using, in, that, the, bats"
59641,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.081967213,"that, is, pangolin, sars-cov-2, the"
59642,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.081967213,"the, and, also, that, bat"
59643,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.081967213,"the, with, and, sars-cov-2, into"
59644,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.081967213,"are, they, but, the, and"
59645,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.081967213,"showed, identity, with, sars-cov-2, the"
59646,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.081967213,"be, of, the, and, in"
59647,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.081967213,"in, the, to, bind, that"
59648,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.081967213,"to, the, of, a, key"
59649,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.081967213,"in, the, as, was, that"
59650,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.081967213,"to, likely, that, is, from"
59651,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.081967213,"be, likely, that, sars-cov-2, from"
59652,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.081967213,"from, such, to, that, sars-cov-2"
59653,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.081967213,"the, an, a, virus, and"
59654,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.081967213,"sars-cov-2, in, the, that, for"
59655,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.081967213,"of, sars-cov-2, to, a, that"
59656,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.081967213,"of, that, origin, a, for"
59657,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.081967213,"to, be, with, of, in"
59658,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.081967213,"that, natural, and, such, are"
59659,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.081967213,"as, a, that, and, to"
59660,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.081967213,"that, human, in, which, and"
59661,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.081967213,"as, to, of, a, human"
59662,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.081967213,"related, to, covs, which, a"
59663,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.081967213,"in, the, with, found, at"
59664,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.081967213,"in, rhinolophus, the, has, with"
59665,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.081967213,"the, that, a, in, animal"
59666,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.081967213,"the, that, sars-, is, from"
59667,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.081967213,"in, the, is, to, of"
59668,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.081967213,"has, the, of, rbd, region"
59669,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.081967213,"also, that, the, and, bat"
59670,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.081967213,"of, and, that, in, southeast"
59671,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.081967213,"of, in, it, is, to"
59672,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.081967213,"it, is, highly, that, of"
59673,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.081967213,"related, to, in, bat, and"
59674,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.081967213,"of, and, in, viruses, bat"
59675,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.081967213,"as, also, the, of, to"
59676,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.081967213,"study, the, as, of, with"
59677,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.081967213,"similar, tion, of, sars-cov-2, and"
59678,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.081967213,"in, be, the, and, of"
59679,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.081818182,"bats, were, for, and, of, study, that, almost, or"
59680,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.081818182,"in, animal, from, found, as, to, species, a, and"
59681,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.081818182,"the, of, a, in, multiple, led, to, that, also"
59682,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.081818182,"from, was, to, that, used, and, in, known, an"
59683,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.081818182,"similarly,, the, and, in, to, that, are, not, of"
59684,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.081818182,"the, also, first, to, this, as, and, in, of"
59685,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.081818182,"the, for, a, with, bat, as, and, human, of"
59686,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.081818182,"on, the, and, january, of, were, to, huanan, market"
59687,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.081818182,"from, the, for, a, that, in, of, isolated, coronavirus"
59688,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.081818182,"and, of, between, sars-cov-2, in, their, the, for, to"
59689,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.081818182,"the, to, in, a, of, with, that, bats, and"
59690,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.081818182,"in, the, of, that, as, to, species, a, closely"
59691,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.081818182,"a, was, at, in, that, the, virus, to, of"
59692,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.081818182,"from, animal, to, a, as, and, found, in, species"
59693,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.081818182,"that, the, of, species, in, as, closely, a, to"
59694,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.081818182,"the, is, by, coronavirus, also, a, two, that, in"
59695,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.081818182,"study, of, and, that, bats, for, almost, were, or"
59696,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.081818182,"in, also, the, of, multiple, that, a, led, to"
59697,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.081818182,"the, that, also, with, of, or, it, as, for"
59698,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.081818182,"that, was, an, to, from, and, known, used, in"
59699,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.081818182,"as, also, the, of, first, and, in, this, to"
59700,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.081818182,"a, for, the, as, of, bat, and, with, human"
59701,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.081818182,"in, the, of, a, coronavirus, isolated, from, that, for"
59702,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.081818182,"to, in, the, including, this, that, for, ace2, of"
59703,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.081818182,"the, that, also, with, of, use, as, an, for"
59704,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.081818182,"to, a, of, in, bats, the, and, that, with"
59705,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.081818182,"on, the, other, by, of, in, and, that, a"
59706,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.081818182,"of, at, the, in, a, to, those, that, animal"
59707,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.081818182,"the, huanan, on, and, market, january, of, were, to"
59708,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.081818182,"the, for, to, that, this, ace2, in, of, including"
59709,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.081818182,"the, of, that, with, as, or, also, it, for"
59710,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.081818182,"the, also, for, that, with, as, of, use, an"
59711,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.081818182,"in, the, that, two, also, by, a, coronavirus, is"
59712,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.081818182,"that, a, the, virus, was, of, in, at, to"
59713,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.081818182,"between, sars-cov-2, and, of, the, to, in, their, for"
59714,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.081818182,"the, in, a, of, on, that, by, and, other"
59715,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.081818182,"the, of, a, to, that, in, animal, those, at"
59716,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.081818182,"the, that, to, are, in, of, and, not, similarly,"
59717,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.081761006,"the, of, a, to, as, by, had, that, this, specific, it, first, its"
59718,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.081761006,"the, live, and, were, in, their, with, of, had, to, we, that, positive"
59719,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.081761006,"its, that, it, to, this, as, first, the, had, by, a, specific, of"
59720,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.081761006,"we, and, of, the, to, live, in, were, with, had, their, that, positive"
59721,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.081632653,"reservoir, a, coronaviruses, in"
59722,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.081632653,"that, a, and, or"
59723,"identified numerous human–animal interactions that con- 

stitute emergence risk factors, for example bat tourism, wet 

markets, wildlife supply chains for human consumption,15 land 

management practices, and environmental perturbations.",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.081632653,"numerous, bat, human, and"
59724,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.081632653,"to, related, sars-cov, are"
59725,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.081632653,"viral, are, in, and"
59726,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.081632653,"the, of, from, humans"
59727,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.081632653,"the, of, from, this"
59728,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.081632653,"the, of, this, virus"
59729,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.081632653,"coronaviruses, have, of, and"
59730,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.081632653,"the, of, most, scientists"
59731,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.081632653,"the, of, past, and"
59732,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.081632653,"of, the, animal, species"
59733,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.081632653,"of, coronavirus, and, with"
59734,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.081632653,"coronavirus, with, that, of"
59735,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.081632653,"that, were, infected, bats, or, animals, and, of"
59736,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.081632653,"in, and, to, have"
59737,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","identified numerous human–animal interactions that con- 

stitute emergence risk factors, for example bat tourism, wet 

markets, wildlife supply chains for human consumption,15 land 

management practices, and environmental perturbations.",0.081632653,"human, and, numerous, bat"
59738,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.081632653,"to, in, and, bats"
59739,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.081632653,"identified, by, from, and"
59740,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.081632653,"the, to, very, and"
59741,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.081632653,"to, the, identified, and"
59742,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.081632653,"sars, and, the, are"
59743,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.081632653,"from, to, bat, the"
59744,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.081632653,"to, the, of, may"
59745,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.081632653,"the, of, with, sars-cov"
59746,"this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.081632653,"a, the, is, of"
59747,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.081632653,"the, sars-cov-2, sequences, of"
59748,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.081632653,"such, and, the, affinity, of, to, that, sars-cov-2"
59749,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.081632653,"the, which, probably, in"
59750,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.081632653,"is, to, a, human"
59751,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.081632653,"the, genetic, sars-cov-2, its"
59752,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.081632653,"sars-cov-2, and, that, is"
59753,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.081632653,"and, their, sars-cov-2, is"
59754,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.081632653,"to, that, these, are"
59755,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.081632653,"of, these, to, bat"
59756,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.081632653,"have, that, the, to"
59757,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.081632653,"to, highly, that, bat"
59758,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.081632653,"the, of, found, that, was, to, a, is"
59759,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.081632653,"the, that, a, found"
59760,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.081632653,"found, of, genome, to"
59761,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.081632653,"of, and, bat, virus"
59762,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.081632653,"of, virus, has, and"
59763,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.081632653,"of, bat, origin, as"
59764,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.081632653,"been, of, virus, and"
59765,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.081632653,"the, a, are, and"
59766,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.081632653,"the, including, of, natural"
59767,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.081632653,"a, of, the, are"
59768,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.081632653,"to, the, suggesting, that"
59769,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.081632653,"ratg13, the, sequence, sars-cov-2"
59770,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.081632653,"analysis, showed, that, of"
59771,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.081632653,"who, and, of, with"
59772,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.081632653,"of, and, in, with"
59773,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.081632653,"to, the, known, and, in, of, sequence, genome"
59774,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.081632653,"to, of, have, sars-cov-2"
59775,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.081632653,"a, that, the, used"
59776,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.081632653,"host, bats, and, the"
59777,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.081632653,"as, the, of, in"
59778,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.081632653,"the, of, pangolins, as"
59779,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.081632653,"from, of, the, humans"
59780,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.081632653,"that, the, wuhan, of"
59781,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.081632653,"to, is, that, the"
59782,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.081632653,"the, that, in, were"
59783,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.081632653,"animal, and, market, in"
59784,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.081632653,"is, sars-cov-2, a, the"
59785,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.081632653,"of, and, the, transmission"
59786,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.081632653,"bats, are, of, and"
59787,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.081632653,"hosts, and, the, disease"
59788,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.081632653,"to, the, for, and"
59789,"Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.081632653,"from, the, that, for"
59790,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.081632653,"natural, and, to, the"
59791,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.081632653,"the, from, and, palm"
59792,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.081632653,"can, that, the, and"
59793,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.081632653,"in, the, and, animals"
59794,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.081632653,"in, the, from, animals"
59795,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.081632653,"that, the, of, outbreak"
59796,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.081632653,"are, sars-cov-2, to, and"
59797,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.081632653,"of, the, are, to"
59798,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.081632653,"this, in, the, to"
59799,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.081632653,"the, be, found, in"
59800,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.081632653,"in, the, a, that"
59801,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.081632653,"that, the, and, origin"
59802,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.081632653,"the, that, was, by"
59803,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.081632653,"by, virus, the, was"
59804,"n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.081632653,"coronaviruses, a, reservoir, in"
59805,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.081632653,"host, animal, to, as"
59806,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.081632653,"from, in, have, been"
59807,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.081632653,"sars-cov-2, been, to, bat"
59808,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.081632653,"in, to, coronaviruses, from"
59809,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.081632653,"between, and, in, sars-cov-2"
59810,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.081632653,"to, the, as, a, of, from, that, humans"
59811,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.081632653,"the, origin, into, sars-cov-2"
59812,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.081632653,"genome, and, have, genomic"
59813,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.081632653,"the, of, that, wuhan"
59814,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.081632653,"bat, coronavirus, at, the"
59815,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.081632653,"and, have, the, from"
59816,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.081632653,"in, the, of, and, at, are, we, viruses"
59817,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.081632653,"that, the, of, in, were, we, a, by"
59818,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.081632653,"humans, of, sars-cov-2, intermediate"
59819,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.081632653,"to, the, known, be, susceptible, and, of, that"
59820,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.081632653,"that, in, the, market, at, and, of, animal"
59821,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.081632653,"in, a, to, that"
59822,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.081632653,"and, the, origin, with"
59823,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.081632653,"the, of, was, by"
59824,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.081632653,"et, al., the, from"
59825,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.081632653,"of, by, a, the"
59826,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.081632653,"the, other, and, from"
59827,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.081632653,"to, viruses, related, in"
59828,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.081632653,"within, and, in, the"
59829,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.081632653,"of, in, to, were"
59830,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.081632653,"from, sars-cov-2, to, and"
59831,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.081632653,"in, a, spillover, to"
59832,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Four other agen- 

cies, along with a national intel- 

ligence panel, still judge that  

SARS-CoV-2 emerged from natu- 

ral zoonotic spillover",0.081632653,"a, sars-cov-2, with, from"
59833,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.081632653,"natural, of, three, the"
59834,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.081632653,"the, in, and, animals"
59835,"insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.081632653,"from, of, animals,, and"
59836,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.081632653,"the, in, those, animal"
59837,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.081632653,"the, of, also, to, a, different, that, in"
59838,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.081632653,"it, that, are, from"
59839,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.081632653,"and, to, viruses, are, other, that, in, is"
59840,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.081632653,"in, are, not, other"
59841,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.081632653,"that, known, viruses, from"
59842,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.081632653,"of, the, we, and, are, at, in, viruses"
59843,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.081632653,"in, the, and, to, of, are, as, they"
59844,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.081632653,"and, in, to, be, sars-cov-2,, the, of, are"
59845,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.081632653,"the, of, sars-cov-2, to, it, is, and, by"
59846,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.081632653,"by, the, of, viruses, in, bats,, to, that, sars, and, or, it"
59847,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.081632653,"viruses, of, the, sars-cov-2, have, in, is, and"
59848,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.081632653,"at, is, the, sars-cov-2, that, are, more, than"
59849,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.081632653,"cases, the, with, by"
59850,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.081632653,"collected, on, that, by"
59851,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.081632653,"that, were, at, on"
59852,"RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.081632653,"at, the, with, sars-cov-2"
59853,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.081632653,"that, sars-cov-2, on, the"
59854,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.081632653,"in, to, evidence, is"
59855,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.081632653,"a, of, the, we, by, that, in, were"
59856,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.081632653,"a, of, the, market, live, were, by, in, to, evidence, that, not"
59857,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.081632653,"animals,, from, and, of"
59858,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.081632653,"such, as, of, and"
59859,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.081632653,"the, and, from, virus"
59860,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.081632653,"the, and, huanan, that"
59861,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.081632653,"the, is, that, this"
59862,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.081632653,"that, virus, and, the"
59863,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.081632653,"have, of, coronaviruses, and"
59864,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.081632653,"and, to, of, a"
59865,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.081632653,"to, a, and, intestinal"
59866,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.081632653,"a, and, to, of"
59867,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.081632653,"in, and, which, have"
59868,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.081632653,"from, cov, and, all"
59869,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.081632653,"genome, the, covid-19, and"
59870,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.081632653,"a, to, coronavirus, that"
59871,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.081632653,"animal, host, to, as"
59872,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.081632653,"the, of, as, to"
59873,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.081632653,"of, the, to, animal"
59874,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.081632653,"that, to, they, in"
59875,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.081632653,"the, cases, with, by"
59876,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.081632653,"the, of, through, by"
59877,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.081632653,"the, first, in, as"
59878,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.081632653,"an, and, the, from"
59879,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.081632653,"of, to, which, from"
59880,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.081632653,"to, a, was, from"
59881,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.081632653,"the, from, a, sars-cov-2"
59882,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.081632653,"to, the, have, sars-cov-2"
59883,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.081632653,"from, the, of, and"
59884,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.081632653,"the, has, from, bat"
59885,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.081632653,"that, the, was, by"
59886,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.081632653,"virus, from, in, the"
59887,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.081632653,"have, that, to, the"
59888,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.081632653,"the, through, to, that"
59889,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.081632653,"the, scientists, of, most"
59890,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.081632653,"through, that, the, to"
59891,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.081632653,"the, diseases, in, and"
59892,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.081632653,"shown, the, of, to"
59893,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.081632653,"was, a, at, the"
59894,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.081632653,"the, all, of, a, as, that, at, virus"
59895,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.081632653,"a, of, is, the"
59896,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.081632653,"the, were, natural, and"
59897,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.081632653,"and, the, to, animals, who, in, were, that"
59898,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.081632653,"the, who, and, to"
59899,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.081632653,"to, may, the, and"
59900,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.081632653,"the, sars-, and, is"
59901,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.081632653,"natural, and, host, or"
59902,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.081632653,"is, host, to, or"
59903,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.081632653,"the, their, and, or"
59904,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.081632653,"natural, and, the, for"
59905,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.081632653,"for, the, and, mers-cov,"
59906,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.081632653,"the, bat, as, for"
59907,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.081632653,"study, a, the, and"
59908,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.081632653,"of, bats, host, the"
59909,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.081632653,"the, of, sars-like, bats"
59910,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.081632653,"the, could, be, or"
59911,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.081632653,"have, been, from, in"
59912,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.081632653,"the, on, and, were, with, by, of, had, a, to, at, least"
59913,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.081632653,"and, were, in, the"
59914,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged",0.081632653,"the, however,, that, not"
59915,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.081632653,"the, for, suggesting, that, palm, be, at, market"
59916,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.081632653,"that, the, however,, not"
59917,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","According to the evolutionary tree, SARS-CoV-2 lies close to the 

group of SARS-coronaviruses",0.081632653,"the, to, group, of"
59918,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.081632653,"the, that, a, used"
59919,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.081632653,"the, to, sars-cov, and"
59920,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.081632653,"to, genome, bat, the"
59921,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.081632653,"the, of, beta, which"
59922,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.081632653,"human, and, in, all"
59923,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.081632653,"that, sars-cov-2, emerged, of"
59924,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.081632653,"from, the, of, that"
59925,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.081632653,"are, that, it, from"
59926,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.081632653,"the, from, a, of"
59927,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.081632653,"on, that, by, collected"
59928,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.081632653,"of, is, and, by"
59929,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.081632653,"of, have, is, and"
59930,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.081632653,"bat, is, that, bats"
59931,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.081632653,"that, bats, of, recombination"
59932,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.081632653,"the, which, in, probably"
59933,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.081632653,"bats, the, reservoir, in"
59934,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",Many of these CoVs can infect several animal species as well,0.081632653,"covs, several, of, species"
59935,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.081632653,"to, a, is, human"
59936,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.081632653,"a, that, from, to"
59937,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.081632653,"to, the, from, bat"
59938,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.081632653,"the, to, from, bat"
59939,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.081632653,"to, are, the, sars-cov-2"
59940,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.081632653,"from, to, coronaviruses, in"
59941,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.081632653,"the, and, or, to, in, animal, infected, market"
59942,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.081632653,"the, virus, in, animal"
59943,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.081632653,"in, and, have, to"
59944,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.081632653,"a, and, that, or"
59945,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.081632653,"and, a, sars-cov-2, is"
59946,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.081632653,"sars-, cov-2, bats, in"
59947,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.081632653,"of, sars-cov-2, humans, intermediate"
59948,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.081632653,"of, through, to, that"
59949,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.081632653,"that, to, bats,, and"
59950,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.081632653,"of, is, more, to"
59951,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.081632653,"of, and, that, the"
59952,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.081632653,"that, had, the, virus"
59953,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.081632653,"that, the, of, virus"
59954,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.081632653,"and, of, the, to"
59955,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.081632653,"the, virus, was, by"
59956,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.081632653,"of, the, in, isolated"
59957,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.081632653,"the, in, of, with, was, virus, by, and"
59958,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.081632653,"was, in, the, with"
59959,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.081632653,"the, covid-19, genome, and"
59960,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.081632653,"of, the, from, bats"
59961,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.081632653,"with, to, the, genome"
59962,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.081632653,"diseases, in, the, and"
59963,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.081632653,"with, and, in, of"
59964,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.081632653,"with, and, of, in"
59965,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.081632653,"and, are, of, which"
59966,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.081632653,"for, in, and, of"
59967,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.081632653,"of, bats,, which, in"
59968,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.081632653,"are, for, of, and"
59969,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.081632653,"a, to, sars-cov, or"
59970,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.081632653,"to, is, of, the"
59971,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.081632653,"of, and, with, coronavirus"
59972,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.081632653,"of, with, and, the"
59973,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.081632653,"the, sars, of, approximately, that, virus, to, and"
59974,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.081632653,"other, and, the, from"
59975,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.081632653,"et, al., and, genomic"
59976,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.081632653,"of, and, possible, the"
59977,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.081632653,"virus, the, of, s"
59978,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.081632653,"disease, hosts, and, the"
59979,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.081632653,"of, the, patients, and"
59980,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.081632653,"of, are, and, which"
59981,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.081632653,"on, that, were, at"
59982,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.081632653,"was, first, a, that, and, in, isolated, at"
59983,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.081632653,"first, was, that, in"
59984,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.081632653,"that, the, to, sars-cov"
59985,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.081632653,"of, sequences, genomic, to"
59986,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.081632653,"a, that, from, bat"
59987,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.081632653,"most, coronavirus, in, the"
59988,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.081632653,"the, most, that, from"
59989,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.081632653,"that, sars-cov, and, the"
59990,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.081632653,"of, the, intermediate, hosts"
59991,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.081632653,"to, be, of, bats"
59992,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.081632653,"from, of, sars-cov-2, the"
59993,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.081632653,"that, for, sars-cov-2, animals"
59994,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.081632653,"that, the, sars-cov-2, which"
59995,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Bats are natural hosts of many of the known  

coronaviruses",0.081632653,"of, bats, the, coronaviruses"
59996,"a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.081632653,"a, derived, coronavirus, sars-cov-2"
59997,"bats are also important reservoir species for a great 

range of coronaviruses","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.081632653,"bats, species, a, coronaviruses"
59998,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.081632653,"in, bats, and, as"
59999,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.081632653,"is, to, be, in"
60000,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.081632653,"of, but, that, the"
60001,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.081632653,"the, to, of, a"
60002,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.081632653,"of, that, with, coronavirus"
60003,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.081632653,"to, with, of, in"
60004,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.081632653,"the, sars-cov-2, of, human"
60005,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.081632653,"the, of, human, with"
60006,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.081632653,"the, to, suggesting, that"
60007,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.081632653,"the, to, is, on"
60008,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.081632653,"to, of, and, bats"
60009,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.081632653,"bat, ratg13,, sars-cov-2, a"
60010,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis",0.081632653,"of, animal, that, the"
60011,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.081632653,"spike, a, receptor, and"
60012,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.081632653,"of, virus, the, found"
60013,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.081632653,"the, related, to, which"
60014,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.081632653,"the, a, animals, to"
60015,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.081632653,"the, of, these, viruses"
60016,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.081632653,"found, the, of, virus"
60017,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.081632653,"the, health, sampling, of, found, virus, by, a"
60018,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.081632653,"the, a, virus, found"
60019,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.081632653,"the, has, a, in"
60020,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.081632653,"sars-cov, are, related, to"
60021,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.081632653,"are, that, these, to"
60022,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.081632653,"are, this, that, to"
60023,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.081632653,"to, for, and, the"
60024,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.081632653,"to, the, reservoirs, for, zoonotic, and, in, of"
60025,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.081632653,"the, natural, were, and"
60026,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.081632653,"the, host, of, a"
60027,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.081632653,"the, of, genome, a"
60028,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.081632653,"bats, the, for, its"
60029,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.081632653,"sars-cov, a, to, or"
60030,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)",0.081632653,"has, a, mers-cov, to"
60031,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.081632653,"the, with, sars-cov-2, in"
60032,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.081632653,"who, the, were, to, that, in, animals, and"
60033,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.081632653,"sars-cov-2, in, that, the"
60034,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.081632653,"of, with, sars-cov-2, than"
60035,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.081632653,"sars-, cov-2, in, bats"
60036,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.081632653,"an, with, from, to, the, in, of, a"
60037,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.081632653,"which, sars-cov-2, the, genome"
60038,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.081632653,"the, from, sars-cov-2, and"
60039,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","a bat- 

derived coronavirus (the RmYN02 strain) shared 93.3% similarity with 

SARS-CoV-2",0.081632653,"sars-cov-2, a, derived, coronavirus"
60040,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.081632653,"a, bat, strain, in"
60041,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.081632653,"similar, to, the, that"
60042,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.081632653,"the, by, a, of"
60043,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.081632653,"shows, and, of, the"
60044,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.081632653,"to, in, sars-cov-2, the"
60045,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.081632653,"in, et, al., found"
60046,"he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.081632653,"the, et, al., from"
60047,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.081632653,"the, as, in, from"
60048,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.081632653,"from, the, has, sars-cov-2"
60049,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.081632653,"the, has, as, and"
60050,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","bats are also important reservoir species for a great 

range of coronaviruses",0.081632653,"a, coronaviruses, species, bats"
60051,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.081632653,"from, the, to, ace2, and, in, of, an"
60052,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.081632653,"the, ratg13, sequence, sars-cov-2"
60053,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.081632653,"sars-cov-2, has, the, of"
60054,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.081632653,"amino, acid, in, the"
60055,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.081632653,"the, coronaviruses, sars-cov-2, in"
60056,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.081632653,"the, sars-cov-2, with, at"
60057,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.081632653,"is, to, and, the"
60058,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.081632653,"the, in, amino, acid"
60059,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.081632653,"the, ace2, a, in"
60060,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.081632653,"sars-cov-2, of, affinity, to, such, that, and, the"
60061,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.081632653,"the, that, animal, of"
60062,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.081632653,"the, a, intermediate, as"
60063,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.081632653,"that, sars-cov-2, a, or"
60064,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.081632653,"sars-cov-2, the, amino, acid"
60065,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.081632653,"the, to, is, by, of, it, and, sars-cov-2"
60066,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.081632653,"of, the, by, through"
60067,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.081632653,"and, is, by, of"
60068,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.081632653,"and, the, of, by"
60069,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.081632653,"is, of, humans, and"
60070,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.081632653,"be, possible, for, sars-cov-2"
60071,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.081632653,"a, the, to, an"
60072,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.081632653,"a, the, as, intermediate"
60073,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.081632653,"were, of, in, to"
60074,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.081632653,"the, species, in, to"
60075,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.081632653,"the, and, in, at"
60076,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.081632653,"from, of, this, the"
60077,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.081632653,"at, this, the, that"
60078,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.081632653,"in, the, that, from"
60079,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.081632653,"sars-cov-2, to, in, with"
60080,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.081632653,"from, that, for, the"
60081,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Bats are the natural reservoir host for  

variety of coronaviruses including SARS-CoV-2. Coronaviruses typically infect bat’s gastrointestinal  

tracts, which do not express furin.",0.081632653,"the, of, for, sars-cov-2."
60082,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.081632653,"of, even, genome, sars-cov-2"
60083,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.081632653,"the, of, sars-cov-2, completely"
60084,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.081632653,"the, or, of, in"
60085,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.081632653,"the, of, or, is"
60086,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.081632653,"of, to, a, in"
60087,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.081632653,"and, are, in, viral"
60088,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.081632653,"the, of, or, in"
60089,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.081632653,"the, and, one, of"
60090,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.081632653,"likely, in, the, or"
60091,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.081632653,"the, which, of, beta"
60092,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.081632653,"beta, the, of, sars-cov-2"
60093,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.081632653,"the, of, and, as"
60094,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.081632653,"sars-cov-2, to, the, most"
60095,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.081632653,"the, in, sars-cov-2, coronaviruses"
60096,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.081632653,"in, the, were, for"
60097,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.081632653,"the, other, to, virus"
60098,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.081632653,"of, the, bat, species"
60099,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.081632653,"to, of, and, in"
60100,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.081632653,"the, within, in, and"
60101,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.081632653,"species, to, in, the"
60102,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.081632653,"in, also, different, the, of, that, a, to"
60103,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.081632653,"are, that, other, to, and, is, viruses, in"
60104,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.081632653,"of, to, have, sars-cov-2"
60105,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.081632653,"a, sars-cov-2, to, which"
60106,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.081632653,"have, sars-cov-2, of, to"
60107,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.081632653,"of, which, sars-cov-2, to"
60108,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.081632653,"of, which, have, to"
60109,"SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.081632653,"from, sars-cov-2, all, with"
60110,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.081632653,"the, bat, coronavirus, at"
60111,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.081632653,"the, which, sars-cov-2, genome"
60112,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.081632653,"the, at, sars-cov-2, is"
60113,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.081632653,"at, the, was, a"
60114,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.081632653,"a, the, with, at, was, and, to, by"
60115,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.081632653,"the, banal, a, at"
60116,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.081632653,"coronaviruses,, genome, with, sars-cov-2"
60117,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.081632653,"are, viruses, to, the"
60118,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.081632653,"the, of, with, that"
60119,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.081632653,"to, of, the, shown"
60120,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.081632653,"of, that, the, ace2"
60121,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.081632653,"to, through, with, of"
60122,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.081632653,"in, viruses, to, human"
60123,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.081632653,"the, of, from, more"
60124,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.081632653,"the, is, also, in"
60125,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.081632653,"of, the, spike, in"
60126,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.081632653,"the, have, a, of"
60127,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.081632653,"a, banal, at, the"
60128,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.081632653,"and, closely, related, the"
60129,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.081632653,"a, to, and, intestinal"
60130,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.081632653,"and, to, a, in"
60131,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.081632653,"is, bat, to, the"
60132,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.081632653,"the, bat, of, virus"
60133,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.081632653,"and, as, in, bats"
60134,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.081632653,"the, and, may, to"
60135,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.081632653,"of, and, who, with"
60136,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.081632653,"who, the, to, and"
60137,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.081632653,"at, was, the, with"
60138,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.081632653,"and, that, the, virus, approximately, to, sars, of"
60139,". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.081632653,"a, of, virus, sampling, by, the, health, found"
60140,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.081632653,"the, that, at, of, virus, and, less, to"
60141,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.081632653,"that, the, of, market, in, to, live, were, evidence, not, a, by"
60142,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.081632653,"the, known, and, to, in, of, genome, sequence"
60143,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.081632653,"the, that, known, to, be, susceptible, and, of"
60144,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.081632653,"to, the, for, in, zoonotic, reservoirs, and, of"
60145,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.081632653,"the, viruses, that, to, sars, in, by, of, or, bats,, it, and"
60146,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.081632653,"the, in, of, similar, to, that, also, virus"
60147,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.081632653,"a, of, in, bats, the, as, horseshoe, china"
60148,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.081632653,"of, the, in, and, that, a, with, viruses"
60149,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.081632653,"that, also, similar, to, and, a, the, of"
60150,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.081632653,"coronaviruses, were, related, to, in, bats, and, from"
60151,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.081632653,"that, was, first, isolated, and, in, at, a"
60152,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.081632653,"in, an, ace2, from, of, to, and, the"
60153,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.081632653,"of, animals, and, that, bats, were, infected, or"
60154,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.081632653,"the, of, animal, and, market, that, at, in"
60155,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.081632653,"the, of, on, a, or, that, this, evidence"
60156,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.081632653,"of, evidence, that, the, a, from, animal, or"
60157,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.081632653,"and, by, virus, with, the, was, in, of"
60158,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.081632653,"virus, in, province, is, with, the, of, on"
60159,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.081632653,"to, and, of, bats,, is, that, viruses, in"
60160,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.081632653,"of, from, to, an, a, in, with, the"
60161,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.081632653,"the, at, market, for, suggesting, that, palm, be"
60162,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.081632653,"the, animal, in, market, or, infected, to, and"
60163,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.081632653,"the, that, sars-cov-2, with, at, of, and, to"
60164,"Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.081632653,"of, the, shows, and"
60165,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.081632653,"a, on, which, of"
60166,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.081632653,"the, to, a, and"
60167,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.081632653,"one, of, to, a"
60168,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.081632653,"the, to, in, this"
60169,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.081632653,"the, known, in, to"
60170,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.081632653,"and, the, in, markets"
60171,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.081632653,"all, human, in, and"
60172,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.081632653,"that, to, sars-cov-2, humans"
60173,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","expended to make the simple point 

that COVID-19 had a natural origin.",0.081632653,"the, to, that, natural"
60174,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.081632653,"in, that, and, sars-cov-2"
60175,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.081632653,"in, to, coronaviruses, from, bats, and, were, related"
60176,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.081632653,"sars-cov-2, that, found, to"
60177,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.081632653,"from, in, china, and"
60178,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.081632653,"natural, to, and, the"
60179,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.081632653,"in, a, of, to"
60180,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.081632653,"and, natural, or, host"
60181,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.081632653,"the, its, that, sars-cov-2"
60182,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.081632653,"sars-cov-2, a, that, or"
60183,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.081632653,"this, evidence, that, the, a, or, of, on"
60184,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.081632653,"emerged, that, of, sars-cov-2"
60185,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.081632653,"that, of, sars-cov-2, a"
60186,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.081632653,"the, is, used, that"
60187,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.081632653,"the, natural, of, including"
60188,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.081632653,"that, sars-cov-2, similarity, to"
60189,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.081632653,"that, of, the, which"
60190,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.081632653,"the, of, and, by"
60191,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","r. It is possible that a  

progenitor of SARS-CoV-2 jumped into  

humans, acquiring the genomic features  

described above through adaptation during  

undetected human-to-human transmission.",0.081632653,"the, it, that, of"
60192,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.081632653,"of, this, the, virus"
60193,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.081632653,"the, of, in, to, that, virus, similar, also"
60194,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.081632653,"the, of, pangolins, sars-cov-2"
60195,"If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.081632653,"or, in, close, to"
60196,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.081632653,"is, to, or, through"
60197,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.081632653,"the, and, not, to"
60198,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.081632653,"the, analysis, of, that"
60199,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.081632653,"the, of, a, genome"
60200,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",0.081632653,"of, bat, a, the"
60201,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.081632653,"found, that, the, a"
60202,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.081632653,"the, virus, animal, in"
60203,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.081632653,"a, in, the, ace2"
60204,"ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.081632653,"receptor, a, spike, and"
60205,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.081632653,"and, bats,, that, to"
60206,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.081632653,"to, and, bats,, that"
60207,"Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.081632653,"of, species, the, animal"
60208,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.081632653,"bat, as, of, origin"
60209,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.081632653,"the, hosts, of, intermediate"
60210,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.081632653,"bat, species, the, of"
60211,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.081632653,"that, the, of, ace2"
60212,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.081632653,"evidence, that, from, the, a, or, of, animal"
60213,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.081632653,"a, on, of, which"
60214,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.081632653,"is, a, which, on"
60215,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.081632653,"in, humans, animals, to"
60216,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.081632653,"are, to, and, in"
60217,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.081632653,"intermediate, to, humans, in"
60218,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.081632653,"is, be, to, in"
60219,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.081632653,"the, of, and, most"
60220,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.081632653,"bats, the, these, of, to, and, in, been"
60221,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.081632653,"the, reservoir, in, bats"
60222,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.081632653,"viruses, that, are, and"
60223,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.081632653,"the, that, were, in"
60224,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.081632653,"the, in, be, found"
60225,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.081632653,"that, animals, in, with"
60226,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.081632653,"the, of, a, in, horseshoe, bats, as, china"
60227,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.081632653,"the, have, in, of"
60228,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.081632653,"one, the, of, that"
60229,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.081632653,"bats, to, be, of"
60230,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.081632653,"in, with, to, of"
60231,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.081632653,"through, of, with, to"
60232,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.081632653,"from, humans, the, to"
60233,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.081632653,"to, from, and, is"
60234,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.081632653,"to, the, bats, and"
60235,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.081632653,"bats, the, and, host"
60236,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.081632653,"closely, related, and, the"
60237,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.081632653,"in, humans, the, and"
60238,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","If 

live or recently killed bats are placed in close proximity to 

live carnivores or pangolins, virus transmission will be 

theoretically possible.",0.081632653,"to, in, close, or"
60239,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.081632653,"to, the, been, in, bats, of, and, these"
60240,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.081632653,"the, viruses, have, in, is, of, and, sars-cov-2"
60241,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.081632653,"and, have, is, of"
60242,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.081632653,"the, virus, from, in"
60243,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.081632653,"of, the, virus, s"
60244,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.081632653,"the, in, of, with, is, on, virus, province"
60245,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.081632653,"pangolins, the, sars-cov-2, on"
60246,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","t some virus detected in pangolins 

were capable of infecting humans.",0.081632653,"in, virus, of, were"
60247,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.081632653,"et, al., found, in"
60248,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.081632653,"at, all, that, the, virus, as, of, a"
60249,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.081632653,"a, the, with, at, least, on, and, of, were, to, by, had"
60250,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.081632653,"the, an, and, from"
60251,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.081632653,"markets, and, in, the"
60252,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.081632653,"a, of, the, is"
60253,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.081632653,"the, which, related, to"
60254,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.081632653,"related, covs, which, to"
60255,Many of these CoVs can infect several animal species as well,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.081632653,"of, covs, several, species"
60256,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.081632653,"from, a, that, bat"
60257,"Comparatively, SARS-CoV-2 has a lower similarity genome to 

SARS-CoV (∼79%) or MERS-CoV (∼50%)","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.081632653,"has, a, to, mers-cov"
60258,"identified numerous human–animal interactions that con- 

stitute emergence risk factors, for example bat tourism, wet 

markets, wildlife supply chains for human consumption,15 land 

management practices, and environmental perturbations.","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.081632653,"that, bat, human, and"
60259,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.081632653,"ratg13,, sars-cov-2, a, bat"
60260,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.081632653,"and, on, the, in"
60261,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.081632653,"of, is, humans, and"
60262,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.081632653,"the, virus, other, to"
60263,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.081632653,"by, the, are, other"
60264,"S1/S2 cleavage sites of coronaviruses are frequently modi- 

fied by insertions or deletions (indels) during evolution","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.081632653,"of, are, by, or"
60265,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.081632653,"data, that, has, to"
60266,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.081632653,"are, other, not, in"
60267,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.081632653,"in, the, coronavirus, most"
60268,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.081632653,"the, are, by, other"
60269,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.081632653,"sars-cov-2, to, that, bat"
60270,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.081632653,"in, that, sars-cov-2, to"
60271,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.081632653,"to, is, or, host"
60272,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.081632653,"is, to, through, or"
60273,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.081632653,"the, is, of, or"
60274,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.081632653,"is, the, with, or"
60275,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.081632653,"the, of, that, with"
60276,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.081632653,"to, in, that, they"
60277,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.081632653,"sars-cov-2, that, humans, to"
60278,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.081632653,"sars-cov-2, to, that, in"
60279,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.081632653,"the, of, that, but"
60280,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.081632653,"a, the, that, human"
60281,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.081632653,"the, past, of, and"
60282,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.081632653,"the, has, and, as"
60283,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.081632653,"is, evidence, in, to"
60284,"we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.081632653,"of, sars-cov-2, and, their"
60285,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.081632653,"a, on, which, is"
60286,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.081632653,"is, the, a, bat"
60287,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.081632653,"that, are, and, viruses"
60288,"Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.081632653,"bats, are, and, of"
60289,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.081632653,"of, than, sars-cov-2, with"
60290,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.081632653,"sars-cov-2, even, of, genome"
60291,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.081632653,"with, coronaviruses,, sars-cov-2, genome"
60292,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.081632653,"similarity, of, sars-cov-2, ratg13"
60293,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.081632653,"that, from, known, viruses"
60294,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.081632653,"the, from, that, most"
60295,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.081632653,"identified, from, by, and"
60296,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.081632653,"the, and, identified, to"
60297,"SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.081632653,"and, ratg13, to, the"
60298,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.081632653,"sars-cov-2, the, its, genetic"
60299,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.081632653,"sars-cov-2, completely, the, of"
60300,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.081632653,"and, their, of, sars-cov-2"
60301,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","we observed similar substitu- 

tion patterns distinguishing nucleotide sequences of SARS-CoV-2 

and SARS-CoV from their closest described bat relatives RaTG13 

and Rs4231",0.081632653,"bat, and, sars-cov-2, ratg13"
60302,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.081632653,"of, which, in, bats,"
60303,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.081632653,"sars-cov-2, the, of, in"
60304,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.081632653,"the, a, has, in"
60305,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.081632653,"is, also, in, the"
60306,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.081632653,"the, that, is, used"
60307,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.081632653,"the, bats, for, its"
60308,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.081632653,"pangolins, sars-cov-2, the, on"
60309,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.081632653,"that, sars-cov-2, and, evidence"
60310,"t some virus detected in pangolins 

were capable of infecting humans.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.081632653,"virus, in, were, of"
60311,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.081632653,"the, that, as, to"
60312,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.081632653,"is, a, the, bat"
60313,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.081632653,"the, of, a, to, that, sars, and, virus"
60314,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.081632653,"sars-cov-2, bat, the, in"
60315,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.081632653,"of, bat, these, to"
60316,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.081632653,"to, a, from, was"
60317,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.081632653,"one, of, a, to"
60318,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.081632653,"to, in, bat, which"
60319,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.081632653,"sars-cov-2, a, and, is"
60320,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.081632653,"of, similarity, sars-cov-2, ratg13"
60321,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.081632653,"found, genome, of, to"
60322,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.081632653,"genomic, have, and, genome"
60323,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.081632653,"have, in, which, and"
60324,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.081632653,"et, al., genomic, and"
60325,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.081632653,"sequences, genomic, to, of"
60326,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.081632653,"to, related, in, and"
60327,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.081632653,"to, of, which, have"
60328,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.081632653,"related, to, covs, which"
60329,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.081632653,"that, sars-cov-2, animals, for"
60330,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.081632653,"sars-cov-2, be, possible, for"
60331,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.081632653,"that, in, with, animals"
60332,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.081632653,"study, that, with, an"
60333,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.081632653,"virus, and, been, of"
60334,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.081632653,"the, of, a, viruses, in, that, with, and"
60335,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.081632653,"to, is, pangolin, sars-cov-2"
60336,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.081632653,"the, viruses, are, to"
60337,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.081632653,"the, and, or, sa"
60338,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.081632653,"are, for, the, and"
60339,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.081632653,"the, that, are, more, is, than, sars-cov-2, at"
60340,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.081632653,"the, that, this, at"
60341,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.081632653,"the, in, to, with"
60342,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.081632653,"the, likely, or, in"
60343,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.081632653,"have, the, or, in"
60344,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.081632653,"with, the, or, is"
60345,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.081632653,"to, which, bat, in"
60346,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.081632653,"as, in, the, of, and, are, to, they"
60347,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.081632653,"the, this, that, in"
60348,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.081632653,"that, sars-cov-2, the, which"
60349,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.081632653,"that, sars-cov-2, similarity, the"
60350,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.081632653,"that, the, s, pangolin"
60351,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa",0.081632653,"that, sars-cov-2, than, the"
60352,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.081632653,"sars-cov-2, the, of, sequences"
60353,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.081632653,"the, and, their, or"
60354,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.081632653,"also, that, the, pangolin"
60355,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.081632653,"the, sars, and, are"
60356,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.081632653,"the, sars-cov-2, into, origin"
60357,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.081632653,"with, and, origin, the"
60358,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.081632653,"have, are, the, and"
60359,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.081632653,"that, bats, have, in"
60360,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.081632653,"the, of, virus, bat"
60361,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.081632653,"in, and, china, from"
60362,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.081632653,"the, of, from, virus"
60363,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.081632653,"the, on, that, sars-cov-2"
60364,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.081632653,"the, of, a, to, that, and, similar, also"
60365,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.081632653,"the, also, to, a, that, similar, and, of"
60366,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.081632653,"similarity, to, sars-cov-2, that"
60367,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.081632653,"has, that, data, to"
60368,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.081632653,"sars-cov-2, the, is, of"
60369,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.081632653,"with, the, of, sars-cov"
60370,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.081632653,"sars-cov-2, between, and, in"
60371,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.081632653,"from, and, the, palm"
60372,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.081632653,"of, are, and, for"
60373,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.081632653,"have, and, the, of"
60374,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.081632653,"and, have, the, are"
60375,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.081632653,"a, of, for, that"
60376,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.081632653,"all, cov, and, from"
60377,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.081632653,"all, from, with, sars-cov-2"
60378,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","SARS-CoV isolates from humans, CoV isolates from civets and SARS-like  

CoV isolates from bats, whilst Sarbeco-III consist (i) SARS-CoV-2 iso­ 

lated from humans, (ii) SARS-like CoVs isolated from bats, and Pangolin-  

CoV. All SARS-CoV-2 isolates tightly clustered together with more than  

99% similarity",0.081632653,"sars-cov-2, with, and, similarity"
60379,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.081632653,"the, is, with, and"
60380,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.081632653,"are, the, and, in"
60381,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.081632653,"the, and, natural, for"
60382,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.081632653,"less, the, of, that, at, virus, to, and"
60383,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.081632653,"with, the, and, of, to, that, sars-cov-2, at"
60384,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.081632653,"can, that, and, the"
60385,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.081632653,"in, of, be, that"
60386,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.081632653,"that, bats, recombination, of"
60387,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.081632653,"that, the, similarity, sars-cov-2"
60388,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.081632653,"in, the, those, animal"
60389,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.081632653,"as, the, first, in"
60390,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.081632653,"for, the, as, bat"
60391,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.081632653,"sars-cov-2, the, bat, and"
60392,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.081632653,"a, study, the, and"
60393,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.081632653,"is, sars-cov-2, at, the"
60394,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.081632653,"in, from, sars-cov-2, the"
60395,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.081632653,"the, in, from, that"
60396,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.081632653,"human, that, a, the"
60397,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.081632653,"the, to, an, of"
60398,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.081632653,"the, to, and, not"
60399,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.081632653,"in, from, a, china"
60400,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.081632653,"from, in, sars-cov-2, of"
60401,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.081632653,"of, in, bat, including"
60402,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.081632653,"the, and, mers-cov,, for"
60403,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.081632653,"are, the, and, for"
60404,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.081632653,"to, coronavirus, that, a"
60405,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.081632653,"a, of, in, to"
60406,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.081632653,"that, for, a, of"
60407,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.081632653,"in, be, that, of"
60408,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.081632653,"with, the, was, in"
60409,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.081632653,"the, was, at, with"
60410,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.081632653,"in, at, with, the"
60411,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.081632653,"of, the, three, natural"
60412,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.081632653,"in, the, of, spike"
60413,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.081632653,"in, the, of, and, are, to, be, sars-cov-2,"
60414,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.081632653,"the, s, of, to"
60415,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.081632653,"that, to, highly, bat"
60416,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.081632653,"viruses, in, related, to"
60417,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.081632653,"to, in, of, viruses, bats,, is, that, and"
60418,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.081632653,"of, bat, in, including"
60419,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.081632653,"of, is, related, to"
60420,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.081632653,"an, of, to, the"
60421,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.081632653,"have, of, the, as"
60422,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.081632653,"that, study, an, with"
60423,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.081632653,"s, that, the, pangolin"
60424,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.081632653,"the, to, of, s"
60425,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.081632653,"is, more, of, to"
60426,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.081632653,"to, of, is, related"
60427,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","SARS-CoV-2 and bat RaTG13 showing 96% 

identity some pangolin Coronaviruses exhibit very high similarity to particularly the receptor-binding 

domain of SARS-CoV-2.",0.081632653,"to, the, ratg13, and"
60428,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.081632653,"analysis, the, a, that"
60429,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.081632653,"a, the, that, or"
60430,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.081481481,"the, to, a, of, with, on, was, were, by, and, market"
60431,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.081481481,"on, in, the, and, that, of, samples, were, to, taken, from"
60432,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.081481481,"a, the, with, was, on, and, market, of, were, to, by"
60433,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.081481481,"in, the, of, to, on, taken, samples, were, and, that, from"
60434,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.081395349,"sars-cov-2, a, virus, that, to, the, for"
60435,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.081395349,"the, of, to, as, bats, close, for"
60436,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.081395349,"the, of, as, and, in, has, been"
60437,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.081395349,"the, to, a, of, is, animal, and"
60438,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.081395349,"the, to, are, of, can, and, sars-cov-2"
60439,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.081395349,"a, coronavirus, the, that, to, of, at"
60440,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.081395349,"genetic, had, been, one, of, the, for"
60441,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.081395349,"the, of, to, such, as, and, more"
60442,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.081395349,"the, of, in, as, viruses, to, genetic"
60443,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.081395349,"of, at, the, in, to, sars-cov-2,, such"
60444,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.081395349,"the, of, sars-cov-2, are, and, can, to"
60445,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.081395349,"the, that, cases, before, were, by, with"
60446,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.081395349,"is, a, from, as, to, that, in"
60447,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.081395349,"the, in, of, and, that, animals, a"
60448,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.081395349,"the, of, have, to, animals, market, at"
60449,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.081395349,"of, to, a, that, in, and, the"
60450,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.081395349,"or, which, the, of, to, in, been"
60451,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.081395349,"and, of, bat, bats, that, recombination, is"
60452,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.081395349,"to, from, in, the, sars, of, also"
60453,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.081395349,"a, of, with, palm, the, or, to"
60454,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.081395349,"as, the, of, and, to, more, such"
60455,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.081395349,"infected, the, and, of, main, animal, are"
60456,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.081395349,"of, the, bat, and, are, sequences, viruses"
60457,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.081395349,"for, from, samples, the, huanan, seafood, of"
60458,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.081395349,"in, a, to, that, is, from, as"
60459,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.081395349,"and, be, that, sars-cov-2, in, from, a"
60460,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.081395349,"the, of, a, which, and, at, sars-cov"
60461,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.081395349,"that, to, at, the, coronavirus, a, of"
60462,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.081395349,"a, the, was, rather, than, human, to"
60463,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.081395349,"bat, a, in, the, zoonotic, of, and"
60464,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.081395349,"and, the, it, be, that, of, sars-cov-2"
60465,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.081395349,"and, the, to, a, infect, that, in"
60466,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.081395349,"the, is, for, of, to, by, and"
60467,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.081395349,"as, in, the, of, to, viruses, genetic"
60468,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.081395349,"close, to, the, of, bats, as, for"
60469,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.081395349,"and, that, is, bats, recombination, of, bat"
60470,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.081395349,"a, that, the, to, infect, and, in"
60471,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.081395349,"and, can, the, of, which, that, a"
60472,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.081395349,"this, the, in, that, bats, are, for"
60473,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.081395349,"also, that, the, and, bat, is, viruses"
60474,"We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.081395349,"the, was, to, human, rather, than, a"
60475,"In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.081395349,"in, the, case, of, a, was, patients"
60476,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.081395349,"a, to, the, of, with, palm, or"
60477,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.081395349,"to, the, in, of, and, that, a"
60478,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.081395349,"found, in, to, that, of, nucleotide, and"
60479,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.081395349,"the, of, sars, in, also, to, from"
60480,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.081395349,"the, of, a, zoonotic, and, in, bat"
60481,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.081395349,"for, and, to, the, zoonotic, of, virus"
60482,"Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.081395349,"animal, and, infected, are, the, main, of"
60483,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.081395349,"that, bats, are, the, a, of, and"
60484,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.081395349,"is, to, a, of, animal, and, the"
60485,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.081395349,"most, of, the, in, that, was, by"
60486,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.081395349,"of, samples, from, the, huanan, seafood, for"
60487,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.081395349,"the, cases, that, with, were, by, before"
60488,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.081395349,"the, of, to, is, for, and, by"
60489,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.081395349,"covid-19, a, in, the, that, but, for"
60490,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.081395349,"that, with, the, of, have, to, an"
60491,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.081395349,"sars-cov-2, a, and, from, be, that, in"
60492,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.081395349,"and, the, of, it, be, that, sars-cov-2"
60493,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.081395349,"sars-cov-2, for, to, a, virus, that, the"
60494,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.081395349,"one, the, had, of, genetic, been, for"
60495,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.081395349,"and, the, of, a, that, which, can"
60496,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.081395349,"the, in, of, most, was, that, by"
60497,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.081395349,"a, the, of, and, in, animals, that"
60498,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.081395349,"has, been, the, in, of, as, and"
60499,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.081395349,"of, to, the, in, which, been, or"
60500,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.081395349,"have, to, the, of, animals, at, market"
60501,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.081395349,"the, of, and, sars-cov, at, which, a"
60502,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","In the case of Covid-19, a link was established between 

the first patients and the wildlife market of Wuhan.",0.081395349,"a, the, was, case, of, in, patients"
60503,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.081395349,"the, animals, a, of, is, that, and"
60504,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.081395349,"to, for, the, virus, zoonotic, of, and"
60505,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.081395349,"and, the, of, a, that, virus, is"
60506,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.081395349,"of, and, that, nucleotide, found, in, to"
60507,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.081395349,"natural, of, the, in, to, that, insertion"
60508,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.081395349,"the, of, and, bat, sequences, viruses, are"
60509,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.081395349,"the, are, bats, that, this, in, for"
60510,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.081395349,"and, the, bat, also, viruses, that, is"
60511,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.081395349,"that, bats, the, a, and, of, are"
60512,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.081395349,"the, that, in, for, a, but, covid-19"
60513,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.081395349,"in, the, of, at, to, sars-cov-2,, such"
60514,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.081395349,"that, the, to, in, insertion, of, natural"
60515,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.081395349,"the, that, have, of, to, with, an"
60516,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.081300813,"to, a, in, the, or, by, live, were, of, other"
60517,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.081300813,"a, the, market, at, and, in, to, infected, that, from"
60518,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.081300813,"of, animal, and, by, an, to, it, that, another, intermediate"
60519,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.081300813,"in, with, the, and, to, that, sars-cov-2, of, bat, pangolin"
60520,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.081300813,"in, the, of, a, to, with, and, that, this, it"
60521,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.081300813,"for, and, together, with, to, the, in, of, its, a"
60522,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.081300813,"the, is, that, in, for, of, to, and, with, a"
60523,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.081300813,"in, the, a, to, by, with, genome, similar, and, it"
60524,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.081300813,"that, the, in, and, to, from, infected, at, a, market"
60525,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.081300813,"and, it, that, of, to, an, intermediate, another, animal, by"
60526,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.081300813,"and, samples, at, the, for, of, in, this, from, a"
60527,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.081300813,"in, the, of, it, to, that, with, and, this, a"
60528,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.081300813,"it, in, by, a, with, and, similar, to, the, genome"
60529,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.081300813,"the, of, in, to, or, live, were, a, by, other"
60530,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.081300813,"and, the, of, to, a, together, with, in, for, its"
60531,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.081300813,"and, the, of, to, a, with, that, in, for, is"
60532,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.081300813,"in, a, of, the, samples, from, for, this, and, at"
60533,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.081300813,"sars-cov-2, and, of, the, to, pangolin, in, with, that, bat"
60534,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.081081081,"of, bats, reservoir"
60535,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.081081081,"the, bats, and, a, in, of, from, that, or"
60536,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.081081081,"coronaviruses, which, sars-cov-2"
60537,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.081081081,"sars-cov-2, a, related"
60538,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.081081081,"of, the, and, into, 2, viruses"
60539,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Coronaviruses are RNA viruses globally distributed in a 

large but unknown number of animal species",0.081081081,"in, unknown, of"
60540,"The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.081081081,"the, viruses, are"
60541,"The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.081081081,"the, two, in"
60542,The COVID-19 most likely developed from bat origin coronaviruses,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.081081081,"the, most, coronaviruses"
60543,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.081081081,"similar, to, and"
60544,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.081081081,"to, genetic, bat"
60545,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.081081081,"bat, sequences, in"
60546,"SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.081081081,"sars-cov-2, of, sars-cov"
60547,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.081081081,"bats, sars-cov-2, to"
60548,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.081081081,"sars-cov-2, and, of"
60549,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.081081081,"in, and, of"
60550,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.081081081,"were, from, and"
60551,"Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.081081081,"and, species, of"
60552,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.081081081,"partial, of, and"
60553,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.081081081,"by, from, species"
60554,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.081081081,"similar, to, the"
60555,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.081081081,"in, sars-cov-2, genome"
60556,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.081081081,"is, one, to"
60557,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.081081081,"bats, also, are"
60558,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.081081081,"sars-cov-2, of, the, with, to, in"
60559,"Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.081081081,"of, have, a"
60560,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.081081081,"have, from, coronavirus"
60561,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.081081081,"is, it, been"
60562,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.081081081,"is, have, which"
60563,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.081081081,"the, that, not, in, to, sars-cov-2"
60564,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.081081081,"the, of, and, have, in, between"
60565,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.081081081,"the, a, of, to, bat, and"
60566,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.081081081,"the, those, and, to, of, are"
60567,"a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.081081081,"a, with, that"
60568,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.081081081,"that, the, as"
60569,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.081081081,"that, sars-cov-2, natural"
60570,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.081081081,"the, have, that"
60571,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.081081081,"that, the, of, was, to, a"
60572,"This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.081081081,"and, origin, of"
60573,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.081081081,"genome, bat, and"
60574,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.081081081,"of, genome, and"
60575,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.081081081,"been, of, as"
60576,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.081081081,"and, of, bat"
60577,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.081081081,"the, and, covs,"
60578,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.081081081,"of, that, and, in, which, were"
60579,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.081081081,"in, and, that, of, pangolin, as"
60580,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.081081081,"sars-cov-2, and, or"
60581,"Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.081081081,"of, family, and"
60582,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.081081081,"sars-cov-2, with, or"
60583,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.081081081,"the, of, that, humans, to, and"
60584,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.081081081,"human, in, used"
60585,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.081081081,"the, that, used"
60586,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.081081081,"other, coronaviruses,, zoonotic"
60587,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.081081081,"of, have, the, are, mammals, as"
60588,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.081081081,"most, are, zoonotic"
60589,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.081081081,"as, and, the, of, have, been"
60590,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.081081081,"that, the, in, was, to, a"
60591,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.081081081,"to, and, considered"
60592,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.081081081,"sars-cov-2, to, transfer"
60593,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.081081081,"the, of, and, only, in, as"
60594,"expended to make the simple point 

that COVID-19 had a natural origin.","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.081081081,"the, point, had"
60595,"Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.081081081,"people, the, infected"
60596,"Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.081081081,"infected, the, of"
60597,"Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.081081081,"market, to, and"
60598,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.081081081,"to, and, a"
60599,"A comparative analysis of genetic data available to date has suggested 

that SARS-CoV-2 originated by the recombination of pangolin-CoV and the bat-CoV-RaTG13-like 

virus","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.081081081,"a, to, and"
60600,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.081081081,"the, origin, to"
60601,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.081081081,"the, origin, a"
60602,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.081081081,"the, and, outbreaks"
60603,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.081081081,"including, the, and"
60604,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.081081081,"the, from, humans"
60605,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.081081081,"in, the, through"
60606,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.081081081,"was, in, china"
60607,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.081081081,"in, the, protein"
60608,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.081081081,"that, bats, the"
60609,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.081081081,"with, the, and, for, a, to, that, in, at"
60610,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.081081081,"the, of, dogs"
60611,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.081081081,"of, and, dogs"
60612,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.081081081,"be, sars-cov-2, are"
60613,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.081081081,"and, that, by"
60614,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.081081081,"the, that, in, by, and, a"
60615,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.081081081,"that, a, not"
60616,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.081081081,"on, and, contact, with, to, contaminated"
60617,"the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.081081081,"the, and, has"
60618,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.081081081,"the, and, have"
60619,"ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.081081081,"coronavirus, from, have"
60620,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.081081081,"the, of, have, and, at, was"
60621,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.081081081,"studies, that, from"
60622,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.081081081,"coronaviruses,, zoonotic, other"
60623,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.081081081,"sars-cov-2, from, multiple"
60624,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.081081081,"and, that, of, were, in, which"
60625,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.081081081,"humans, and, that, of, sars-cov-2, by"
60626,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.081081081,"from, in, at, sars-cov-2, the, of"
60627,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.081081081,"to, and, market"
60628,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.081081081,"that, the, huanan"
60629,"SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.081081081,"to, the, lineage"
60630,"In addition, bats’ unique immune system enables them to 

deal with several viruses more effectively than human beings (K","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.081081081,"in, to, more"
60631,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.081081081,"two, the, show"
60632,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.081081081,"the, lineage, in"
60633,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.081081081,"and, of, origin"
60634,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.081081081,"most, in, coronavirus"
60635,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.081081081,"from, and, the, of, been, in"
60636,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.081081081,"to, animal, the"
60637,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.081081081,"the, because, to"
60638,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.081081081,"that, in, than"
60639,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.081081081,"was, likely, genomic"
60640,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.081081081,"likely, in, and"
60641,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.081081081,"nearly, in, a"
60642,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.081081081,"of, to, in, and, were, at"
60643,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.081081081,"sars-cov-2, in, humans"
60644,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.081081081,"early, cases, the, of, a, to, that, in, sars-cov-2"
60645,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.081081081,"the, to, in, had, virus, and"
60646,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.081081081,"as, to, the, of, be, because"
60647,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.081081081,"to, no, virus, had, and, the"
60648,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.081081081,"sars-cov-2, in, a"
60649,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.081081081,"is, evidence, a"
60650,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.081081081,"that, evidence, is"
60651,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.081081081,"are, the, mammals, have, as, of"
60652,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.081081081,"to, have, a, the, is, same"
60653,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.081081081,"is, we, and, the, that, in"
60654,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.081081081,"on, in, the, of, virus, and"
60655,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.081081081,"from, an, animal"
60656,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.081081081,"a, of, but, and, the, to"
60657,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.081081081,"the, have, in, market, or, to"
60658,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.081081081,"to, the, have, of, that, animals"
60659,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","insulated from diverse kinds of  

animals, such as cats, birds, camels, dogs, bats, mice, and livestock",0.081081081,"of, from, as"
60660,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.081081081,"the, that, indicating"
60661,"RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.081081081,"also, the, animals"
60662,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.081081081,"to, a, zoonotic"
60663,"experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.081081081,"to, that, intestinal"
60664,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.081081081,"of, have, that"
60665,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.081081081,"of, coronaviruses, to"
60666,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.081081081,"origin, from, and"
60667,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.081081081,"and, other, have"
60668,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.081081081,"genome, and, bat"
60669,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.081081081,"to, a, and"
60670,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.081081081,"to, was, the"
60671,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.081081081,"known, to, of"
60672,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.081081081,"to, intermediate, host"
60673,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.081081081,"bats, the, possible"
60674,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.081081081,"the, of, in, a, to, that"
60675,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.081081081,"the, of, in, virus, to, that"
60676,"The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.081081081,"the, in, through"
60677,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.081081081,"of, and, to, in, such, as"
60678,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.081081081,"the, have, identified, to, with, a"
60679,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.081081081,"have, a, the"
60680,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.081081081,"bat, of, the"
60681,Genetic evidence suggesting otherwise is yet to be presented.,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.081081081,"suggesting, is, to"
60682,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.081081081,"in, that, covid-19"
60683,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.081081081,"at, was, the"
60684,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.081081081,"to, the, origin"
60685,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.081081081,"and, likely, in"
60686,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.081081081,"the, to, natural"
60687,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.081081081,"together, and, with"
60688,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.081081081,"because, to, the"
60689,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.081081081,"the, of, palm, positive, for, as, a, is, and"
60690,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.081081081,"among, with, the, and, for, of, a, is, palm"
60691,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.081081081,"natural, of, and, a, as, human"
60692,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.081081081,"the, infected, people"
60693,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected",0.081081081,"the, could, or"
60694,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.081081081,"have, from, common"
60695,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.081081081,"the, outbreaks, and"
60696,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.081081081,"not, but, the"
60697,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.081081081,"the, that, bats"
60698,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.081081081,"the, possible, bats"
60699,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.081081081,"the, were, as, a, in, of, that, have, or"
60700,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.081081081,"a, of, researchers, the, that, with"
60701,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.081081081,"coronavirus, a, with, reservoirs, be, the"
60702,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.081081081,"to, be, the, of, coronavirus, is"
60703,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.081081081,"and, be, as, to, which, bats"
60704,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.081081081,"to, the, bats, of, and, key"
60705,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.081081081,"found, bats, which, to, of, and"
60706,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","According to phylogenetic trees, SARS-CoV is closer 

to SARS-like bat CoVs.",0.081081081,"to, is, sars-cov"
60707,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.081081081,"in, human, used"
60708,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.081081081,"to, spillover, human"
60709,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.081081081,"to, covs, infection"
60710,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.081081081,"to, in, intermediate"
60711,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.081081081,"that, of, bat"
60712,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.081081081,"from, of, the"
60713,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.081081081,"studies, that, have"
60714,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.081081081,"to, sars-cov-2, that"
60715,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.081081081,"sars-cov-2, to, have"
60716,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.081081081,"a, nearly, in"
60717,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.081081081,"and, by, that"
60718,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.081081081,"bats, is, and"
60719,"data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.081081081,"data, that, and"
60720,"The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.081081081,"of, is, and"
60721,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.081081081,"bats, the, in"
60722,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",Many of these CoVs can infect several animal species as well,0.081081081,"of, species, infect"
60723,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.081081081,"to, from, is"
60724,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.081081081,"that, an, is"
60725,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.081081081,"to, a, from"
60726,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.081081081,"to, of, from"
60727,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.081081081,"from, to, in"
60728,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.081081081,"bat, origin, in"
60729,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.081081081,"and, are, in"
60730,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.081081081,"the, in, rhinolophus"
60731,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.081081081,"the, found, in"
60732,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.081081081,"the, market, in, to, or, have"
60733,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.081081081,"that, is, and"
60734,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",0.081081081,"has, virus, bats"
60735,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.081081081,"of, by, that, sars-cov-2, and, humans"
60736,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.081081081,"of, the, this, by, and, in"
60737,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.081081081,"in, with, the, by, and, of"
60738,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",COVID-19 is a zoonotic virus,0.081081081,"virus, is, a"
60739,"At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.081081081,"the, with, genome"
60740,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken",0.081081081,"in, such, as"
60741,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.081081081,"to, from, of, the, and, that"
60742,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.081081081,"the, of, and, that, novel, coronavirus"
60743,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.081081081,"of, with, identity"
60744,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.081081081,"comparison, of, with"
60745,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.081081081,"to, transfer, sars-cov-2"
60746,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.081081081,"and, at, the"
60747,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.081081081,"that, are, conserved, the, to, of"
60748,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.081081081,"in, the, and, of, from, between"
60749,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.081081081,"in, the, of, from, that, for, were, a, coronavirus"
60750,"Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.081081081,"genome, and, of"
60751,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.081081081,"bats, as, to, be, which, and"
60752,"The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.081081081,"the, to, pangolin"
60753,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.081081081,"has, the, sars-cov-2"
60754,"Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.081081081,"the, current, hypothesis"
60755,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.081081081,"a, of, humans."
60756,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.081081081,"been, to, the"
60757,"SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.081081081,"with, a, that"
60758,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.081081081,"the, genome, that"
60759,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Human subjects infected with SARS-CoV-2 are  

currently the main sources of ongoing infection",0.081081081,"the, of, infected"
60760,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.081081081,"at, an, in, chinese, the, identified, exposure, of, and"
60761,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.081081081,"suggesting, be, the"
60762,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.081081081,"the, lineage, to"
60763,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.081081081,"in, sars-cov-2, viruses"
60764,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.081081081,"sars-cov-2, and, between"
60765,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.081081081,"in, many, and"
60766,"the coronavirus  

families cause many zoonotic diseases such as  

enteritis in cows, pigs, pangolins, and birds, as well  

as lung diseases in chicken","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.081081081,"such, as, in"
60767,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.081081081,"furin, cleavage, of"
60768,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.081081081,"been, of, have"
60769,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.081081081,"the, of, various"
60770,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.081081081,"origin, and, from"
60771,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.081081081,"a, ratg13, the"
60772,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","this one jumped from bats origin  

into humans",0.081081081,"origin, from, this"
60773,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.081081081,"human, a, the"
60774,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.081081081,"we, the, than"
60775,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.081081081,"are, most, zoonotic"
60776,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.081081081,"coronavirus, in, most"
60777,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.081081081,"the, and, these, of, a, which, as, well, to"
60778,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.081081081,"has, and, the"
60779,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.081081081,"been, and, the"
60780,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","the presence of a variety 

of zoonotic alphaCoV and betaCoV has been detected in Western 

Europe’s bat populations",0.081081081,"a, bat, in"
60781,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.081081081,"bats, are, also"
60782,"This suggests that the BANAL series may be able to directly infect  

humans.","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.081081081,"this, that, to"
60783,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.081081081,"this, that, bats"
60784,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.081081081,"in, it, the"
60785,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.081081081,"that, the, of, bat, in, caves, events, but, to"
60786,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.081081081,"as, the, of, to, because, be"
60787,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.081081081,"human, to, spillover"
60788,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.081081081,"the, to, may, be, high, of"
60789,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.081081081,"event, the, of"
60790,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.081081081,"the, and, to, virus, had, no"
60791,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.081081081,"sars-cov-, 2, the"
60792,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.081081081,"the, any, virus"
60793,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.081081081,"the, sars-cov-2, virus"
60794,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.081081081,"the, sars-cov-2, to, by, consistent, and"
60795,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.081081081,"sars-cov-2, to, that, not, in, the"
60796,"an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.081081081,"in, related, the"
60797,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.081081081,"to, the, for, and, not, a, in, of, that"
60798,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.081081081,"the, of, which, in, and, were"
60799,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.081081081,"and, from, in, to, the, sars-cov-2"
60800,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.081081081,"the, in, those"
60801,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.081081081,"show, the, two"
60802,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.081081081,"than, of, that"
60803,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.081081081,"of, that, with"
60804,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52",0.081081081,"s, that, than"
60805,"respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.081081081,"to, that, naturally"
60806,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.081081081,"the, and, similar, to, in, rbd"
60807,"The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.081081081,"the, protein, in"
60808,"the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.081081081,"the, a, ratg13"
60809,"we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.081081081,"for, in, the"
60810,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.081081081,"in, with, sars-cov-2"
60811,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.081081081,"a, of, also, and, the, species"
60812,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.081081081,"the, rbd, and, in, to, that"
60813,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.081081081,"the, able, to, that, and, infect, in, isolated, use"
60814,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.081081081,"have, and, the, ability, to, through"
60815,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.081081081,"obtained, in, that, the, to, found"
60816,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.081081081,"the, to, species, and, ability, humans"
60817,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.081081081,"to, from, the"
60818,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.081081081,"a, of, that, the, who, to"
60819,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.081081081,"of, market, in, with, the, to"
60820,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.081081081,"the, and, at"
60821,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.081081081,"banal, to, bat"
60822,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan",0.081081081,"of, in, animal"
60823,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.081081081,"the, of, that, from, to, and"
60824,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.081081081,"the, of, a, to, in, virus"
60825,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Bats are the second  

largest order of mammals, with over 1,230 species.",0.081081081,"with, the, over"
60826,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.081081081,"the, ability, to, species, humans, and"
60827,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.081081081,"and, the, bat, to, viruses, as, other, close, which"
60828,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.081081081,"sars-cov-2, coronaviruses, which"
60829,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.081081081,"sars-cov-2, the, which"
60830,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.081081081,"the, of, progenitor"
60831,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.081081081,"and, of, viruses"
60832,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.081081081,"viruses, to, the"
60833,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.081081081,"the, in, for, were, to, and"
60834,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.081081081,"of, species, and"
60835,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.081081081,"of, the, to, in, but, that, bat, caves, events"
60836,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.081081081,"the, of, in, distinct, that, a"
60837,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.081081081,"as, the, to, bat, close, and, which, viruses, other"
60838,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.081081081,"to, of, known"
60839,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.081081081,"from, have, common"
60840,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.081081081,"of, to, from"
60841,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.081081081,"to, sars-cov-2, known"
60842,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","The three BANAL series viruses are also closely related to SARS-CoV-2 when  

measured by the similarity of sections of their spike proteins.",0.081081081,"similarity, of, sars-cov-2"
60843,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.081081081,"the, that, than"
60844,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","This suggests that the BANAL series may be able to directly infect  

humans.",0.081081081,"to, that, this"
60845,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","This suggests that the BANAL series may be able to directly infect  

humans.",0.081081081,"to, banal, the"
60846,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.081081081,"than, that, in"
60847,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.081081081,"that, to, intestinal"
60848,"t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.081081081,"a, of, have"
60849,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Critically, none of the BANAL series viruses have a furin cleavage  

site at the S1/S2 junction of their spike proteins",0.081081081,"have, a, of"
60850,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.081081081,"a, to, have, the, is, same"
60851,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.081081081,"bat, genetic, to"
60852,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.081081081,"bat, banal, to"
60853,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.081081081,"in, as, and"
60854,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.081081081,"in, and, first"
60855,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.081081081,"known, to, sars-cov-2"
60856,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.081081081,"is, the, similar"
60857,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.081081081,"that, covid-19, in"
60858,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.081081081,"first, in, and"
60859,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.081081081,"and, it, the, that, sars-cov-2, in"
60860,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","The CCDC described that the early events were “consistent with the working theory that perhaps several  

zoonotic events occurred.",0.081081081,"the, zoonotic, with"
60861,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.081081081,"a, of, researchers, the, with, that"
60862,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.081081081,"with, the, by, and, to, of"
60863,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.081081081,"who, that, the, of, a, to"
60864,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.081081081,"of, the, in, to, with, market"
60865,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.081081081,"a, for, the, palm, as, positive, of, is, and"
60866,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.081081081,"in, the, of, a, coronavirus, from, that, were, for"
60867,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.081081081,"the, in, of, only, as, and"
60868,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.081081081,"a, of, and, that, the, or, from, in, bats"
60869,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.081081081,"that, the, in, have, were, or, as, a, of"
60870,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.081081081,"in, the, of, for, not, to, that, and, a"
60871,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.081081081,"and, a, of, in, an, the, viral, for, to"
60872,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.081081081,"in, the, isolated, and, able, to, use, that, infect"
60873,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.081081081,"in, the, of, chinese, and, identified, an, exposure, at"
60874,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.081081081,"a, identified, the, to, have, with"
60875,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.081081081,"the, for, and, to, were, in"
60876,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.081081081,"in, the, a, that, to, at, and, with, for"
60877,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.081081081,"early, cases, in, the, of, that, a, sars-cov-2, to"
60878,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.081081081,"a, for, the, palm, of, among, is, and, with"
60879,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.081081081,"a, of, the, at, by, that, or, other, to"
60880,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.081081081,"the, of, a, to, and, market"
60881,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.081081081,"the, genomic, of, in, and, that"
60882,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.081081081,"this, sars-cov-2, and, the, that, in"
60883,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.081081081,"between, and, the, of, from, in"
60884,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.081081081,"and, in, to, the, evidence, of"
60885,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.081081081,"to, the, that, from, between, and"
60886,"Bats are the second  

largest order of mammals, with over 1,230 species.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.081081081,"the, with, over"
60887,"Malayan pangolins (Manis javanica)  

illegally imported into Guangdong province  

contain coronaviruses similar to SARS- 

CoV-22","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.081081081,"pangolins, coronaviruses, to"
60888,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.081081081,"in, were, to"
60889,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.081081081,"and, sars-cov-2, in"
60890,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.081081081,"natural, in, and"
60891,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.081081081,"sars-cov-2, related, a"
60892,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.081081081,"that, coronavirus, of"
60893,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.081081081,"that, a, it"
60894,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.081081081,"that, of, is"
60895,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.081081081,"is, it, of"
60896,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.081081081,"virus, any, the"
60897,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.081081081,"virus, that, the"
60898,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","Malayan pangolins (Manis javanica)  

illegally imported into Guangdong province  

contain coronaviruses similar to SARS- 

CoV-22",0.081081081,"coronaviruses, to, pangolins"
60899,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.081081081,"in, the, and, that, of, all"
60900,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.081081081,"the, including, and, in, all, however,, of, we, that"
60901,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.081081081,"in, the, a, found, that, virus"
60902,"SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.081081081,"identity, to, and"
60903,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.081081081,"the, that, which"
60904,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",The COVID-19 most likely developed from bat origin coronaviruses,0.081081081,"the, coronaviruses, most"
60905,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.081081081,"that, the, indicating"
60906,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.081081081,"of, the, sars-cov,"
60907,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.081081081,"in, to, can"
60908,"Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.081081081,"to, covs, and"
60909,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.081081081,"to, that, be"
60910,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.081081081,"to, originated, in"
60911,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.081081081,"were, to, in"
60912,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.081081081,"to, in, humans"
60913,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.081081081,"in, china, the"
60914,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.081081081,"have, that, the"
60915,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.081081081,"have, that, of"
60916,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.081081081,"of, was, analysis"
60917,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.081081081,"of, bat, coronaviruses,"
60918,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.081081081,"bats, the, key, to, of, and"
60919,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.081081081,"the, between, and, have, of, in"
60920,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.081081081,"the, which, in, animals, were, virus"
60921,"there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.081081081,"of, rhinolophus, the"
60922,"provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.081081081,"the, known, as"
60923,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.081081081,"of, the, rhinolophus"
60924,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.081081081,"from, species, by"
60925,"In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.081081081,"in, the, lineage"
60926,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.081081081,"and, from, bats"
60927,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.081081081,"and, is, bats"
60928,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.081081081,"is, humans, and"
60929,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","an intermediate host species be- 

tween bats and humans was found in all previous out- 

breaks caused by closely related coronavirus: the masked 

palm civet",0.081081081,"the, in, related"
60930,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.081081081,"contact, with, contaminated, on, and, to"
60931,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.081081081,"a, also, are, by, or, to"
60932,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.081081081,"to, bats, and, pangolins, may, are"
60933,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.081081081,"and, have, the, was, at, of"
60934,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.081081081,"were, at, of, in, and, to"
60935,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.081081081,"to, a, virus, and, was, the"
60936,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.081081081,"the, virus, to, a, of, and"
60937,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.081081081,"the, of, and, which, were, in"
60938,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.081081081,"the, of, to, a, virus, in"
60939,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.081081081,"the, and, market, of, a, to"
60940,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.081081081,"the, virus, in, animals, which, were"
60941,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.081081081,"of, the, from, sars-cov-2, at, in"
60942,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.081081081,"from, in, the, of, is, sars-cov-2"
60943,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","t some virus detected in pangolins 

were capable of infecting humans.",0.081081081,"of, in, pangolins"
60944,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.081081081,"the, of, to, a, and, which, as, well, these"
60945,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.081081081,"however,, we, all, including, the, and, in, that, of"
60946,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.081081081,"an, pangolins, in"
60947,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.",0.081081081,"of, transmission, occurred"
60948,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.081081081,"and, the, a"
60949,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.081081081,"covs, to, infection"
60950,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.081081081,"a, the, of, and, but, to"
60951,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.081081081,"also, a, of, species, and, the"
60952,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.081081081,"the, and, to, have, ability, through"
60953,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.081081081,"the, and, to, a, of, bat"
60954,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.081081081,"a, be, the, coronavirus, with, reservoirs"
60955,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.081081081,"a, the, in, spike, from, pangolin"
60956,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.081081081,"to, the, in, and, be, hosts"
60957,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.081081081,"is, bats, the"
60958,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.081081081,"the, and, bats"
60959,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.081081081,"humans, is, and"
60960,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.081081081,"virus, the, sars-cov-2"
60961,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","zoonotic corona- 

viruses have become an increasing threat to human health,",0.081081081,"have, to, an"
60962,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.081081081,"genomic, was, likely"
60963,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.081081081,"of, origin, a"
60964,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.081081081,"analysis, of, was"
60965,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.081081081,"the, of, a, or, to, that, other, by, at"
60966,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.081081081,"also, are, to, or, a, by"
60967,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.081081081,"are, in, with"
60968,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.081081081,"other, are, the"
60969,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.081081081,"intermediate, host, to"
60970,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.081081081,"in, to, from"
60971,"Theoretically, if people contact or eat the reservoir  

or infected animal, they could be infected","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.081081081,"or, the, could"
60972,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.081081081,"that, is, an"
60973,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.081081081,"in, to, humans"
60974,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.081081081,"the, not, but"
60975,"scientists suspected that Hunan seafood 

market in Wuhan helped the virus spread, however, it was not 

where the outbreak first emerged","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.081081081,"that, the, not"
60976,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.081081081,"have, and, the"
60977,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.081081081,"have, other, and"
60978,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.081081081,"the, have, been, as, of, and"
60979,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.081081081,"sars-cov-2, from, and, multiple, of, as"
60980,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.081081081,"the, for, zoonotic"
60981,"In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.081081081,"the, cov, from"
60982,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.081081081,"previous, the, for"
60983,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.081081081,"sars-cov-2, humans, in"
60984,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans",0.081081081,"animal, in, that"
60985,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.081081081,"the, be, sars-cov-2"
60986,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.081081081,"genome, the, bat"
60987,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.081081081,"the, a, origin"
60988,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.081081081,"has, the, origin"
60989,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.081081081,"evidence, in, the, and, of, to"
60990,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.081081081,"from, a, pangolin, spike, in, the"
60991,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","SARS-CoV- 

2 itself has an over 96% nucleotide identity to RaTG13 and therefore 

could be considered “RaTG13-like”",0.081081081,"has, and, to"
60992,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.081081081,"to, that, are"
60993,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.081081081,"to, was, from"
60994,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.081081081,"bats, found, to, which, of, and"
60995,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.081081081,"of, genome, bat"
60996,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.081081081,"be, the, that"
60997,"this one jumped from bats origin  

into humans","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.081081081,"this, from, origin"
60998,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.081081081,"the, and, that, to, from, between"
60999,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.081081081,"to, the, other"
61000,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.081081081,"its, the, to"
61001,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.081081081,"of, coronaviruses, sars-cov-2"
61002,"Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.081081081,"the, animals, also"
61003,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.081081081,"the, by, in, that, coronavirus, a"
61004,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.081081081,"the, conserved, are, to, that, of"
61005,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.081081081,"to, the, of, may, be, high"
61006,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.081081081,"to, consistent, by, and, the, sars-cov-2"
61007,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.081081081,"the, of, to, suggesting, that, sars-cov-2"
61008,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.081081081,"is, evidence, that"
61009,"’. 

This again substantiates the probable bat or pangolin origin of SARS- 

CoV","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.081081081,"the, bat, pangolin"
61010,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.081081081,"pangolins, and, sars-cov-2"
61011,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.",0.081081081,"that, the, than"
61012,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.081081081,"found, in, the, to, that, obtained"
61013,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.081081081,"covs, and, to"
61014,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.081081081,"in, bat, sequences"
61015,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.081081081,"the, origin, in"
61016,hese close genetic relations suggest that they all have their ecological origin in bat populations,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.081081081,"origin, in, bat"
61017,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.081081081,"was, from, to"
61018,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.081081081,"to, the, viral, for, and, a, in, of, an"
61019,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.081081081,"in, of, found, to, and, related"
61020,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.081081081,"sars-cov-2, are, be"
61021,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.081081081,"in, are, with"
61022,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.081081081,"in, that, for"
61023,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.081081081,"suggests, that, sars-cov-2"
61024,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.081081081,"the, of, novel, coronavirus, that, and"
61025,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.081081081,"that, the, of, in, distinct, a"
61026,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.081081081,"the, that, of, and, genomic, in"
61027,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.081081081,"the, by, coronavirus, a, that, in"
61028,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.081081081,"the, to, been"
61029,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.081081081,"2, and, viruses, of, the, into"
61030,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.081081081,"bat, cov, the, cluster, with, are"
61031,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.081081081,"and, hosts, to, be, in, the"
61032,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.081081081,"the, bat, cov, are, cluster, with"
61033,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.081081081,"the, and, in, we, that, is"
61034,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.081081081,"the, and, that, in, this, to"
61035,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in",0.081081081,"and, the, that, sars-cov-2, in, this"
61036,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.081081081,"and, are, to, those, of, the"
61037,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.081081081,"and, that, of, in, as, pangolin"
61038,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.081081081,"and, by, with, the, in, of"
61039,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.081081081,"the, by, and, to, of, with"
61040,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.081081081,"the, covs,, and"
61041,"he pangolin-CoV- 

2019 S protein sequence shares 97.5% homology with SARS-CoV-2, 

higher than that of BANAL-20-52","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.081081081,"s, than, that"
61042,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.081081081,"the, origin, has"
61043,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.081081081,"that, in, this"
61044,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.081081081,"bats, that, this"
61045,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.081081081,"the, and, for, of, to, that, sars-cov-2, more, than"
61046,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.081081081,"and, are, to, pangolins, bats, may"
61047,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.081081081,"the, of, and, in, on, virus"
61048,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.081081081,"the, of, and, virus, from, in"
61049,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.081081081,"the, are, other"
61050,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.081081081,"data, and, that"
61051,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.081081081,"and, is, of"
61052,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.081081081,"the, is, of, and, with, but"
61053,"Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.081081081,"the, of, sars-cov"
61054,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.081081081,"the, bat-, of"
61055,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.081081081,"that, in, and"
61056,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.081081081,"the, of, event"
61057,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.081081081,"from, the, cov"
61058,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","Previous studies have demonstrated that bats are the ultimate  

reservoir hosts for a number of CoVs, including ancestors of SARS-CoV  

and MERS-CoV",0.081081081,"the, for, previous"
61059,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.081081081,"the, for, is"
61060,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.081081081,"the, bat-sl-cov-2, sars-cov-2"
61061,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.081081081,"natural, and, in"
61062,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.081081081,"the, of, and, at, to, virus"
61063,"The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)","In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.",0.081081081,"the, of, bat-"
61064,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.081081081,"that, the, of, was, to, not"
61065,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.081081081,"that, the, sars-cov-2, to, suggesting, of"
61066,"Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.081081081,"bat-sl-cov-2, the, sars-cov-2"
61067,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.081081081,"the, of, that, virus, in, to"
61068,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.081081081,"at, the, that, of, sars-cov-2, in"
61069,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.081081081,"to, the, of, that, sars-cov-2, in"
61070,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.081081081,"virus, has, bats"
61071,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.081081081,"together, with, and"
61072,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.081081081,"comparison, with, of"
61073,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.081081081,"viruses, of, and"
61074,"preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.081081081,"transmission, of, occurred"
61075,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.081081081,"bat, that, the"
61076,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.081081081,"in, the, those"
61077,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.081081081,"that, origin, the"
61078,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.081081081,"that, for, in"
61079,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).",0.081081081,"sars-cov-2, to, very"
61080,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.081081081,"most, the, of"
61081,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.081081081,"be, the, suggesting"
61082,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.081081081,"it, is, of"
61083,"the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.081081081,"of, sars-cov-2, coronaviruses"
61084,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",evidence suggests bats as its origin,0.081081081,"evidence, origin, as"
61085,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.081081081,"such, as, of, and, in, to"
61086,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.081081081,"a, as, natural, of, and, human"
61087,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.081081081,"at, the, was"
61088,"From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.081081081,"with, genome, the"
61089,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.081081081,"the, of, coronavirus, is, to, be"
61090,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.081081081,"in, to, the, sars-cov-2, from, and"
61091,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.081081081,"from, in, is, sars-cov-2, the, of"
61092,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.081081081,"that, and, to, the, in, rbd"
61093,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.081081081,"from, as, and, multiple, of, sars-cov-2"
61094,"zoonotic corona- 

viruses have become an increasing threat to human health,","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.081081081,"have, an, to"
61095,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.081081081,"of, the, in, to, with, sars-cov-2"
61096,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.081081081,"the, and, in, rbd, similar, to"
61097,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered",0.081081081,"that, suggests, sars-cov-2"
61098,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.080882353,"in, the, of, a, by, viruses, were, and, that, from, this"
61099,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.080882353,"the, could, by, of, known, to, as, and, in, isolated, also"
61100,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.080882353,"a, of, the, from, this, by, that, and, in, viruses, were"
61101,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.080882353,"in, with, the, results, by, and, to, that, of, bat, as"
61102,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.080882353,"and, from, in, were, found, to, be, that, the, of, likely"
61103,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.080882353,"the, also, to, as, and, could, by, in, of, isolated, known"
61104,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.080882353,"in, the, of, results, to, bat, as, by, with, and, that"
61105,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.080882353,"in, the, of, to, found, be, were, and, that, likely, from"
61106,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.080808081,"not, a, of, have, and, the, ability, to"
61107,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.080808081,"to, the, as, several, that, have, identical, genome"
61108,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.080808081,"sars-cov-2, of, the, to, sars-cov, found, that, bat"
61109,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.080808081,"the, of, a, to, that, this, sars-cov-2, at"
61110,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.080808081,"in, of, to, from, two, and, at, were"
61111,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.080808081,"than, the, of, that, was, to, were, and"
61112,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.080808081,"is, to, its, in, the, that, it, not"
61113,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.080808081,"of, to, the, from, which, coronavirus, and, virus"
61114,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.080808081,"an, to, animal, the, by, suggesting, of, and"
61115,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.080808081,"the, that, to, have, is, of, and, sars-cov-2"
61116,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.080808081,"the, as, a, in, of, from, those, isolated"
61117,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.080808081,"and, the, have, been, to, animal, in, may"
61118,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.080808081,"an, to, animal, by, of, and, bats,, species"
61119,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.080808081,"of, the, coronavirus, bat, and, genome, other, virus"
61120,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person",0.080808081,"from, the, to, a, live, that, and, in"
61121,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.080808081,"the, in, a, of, with, virus, yunnan, and"
61122,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.080808081,"the, in, with, of, a, to, that, at"
61123,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.080808081,"the, of, a, in, that, and, for, scientific"
61124,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.080808081,"found, that, the, of, sars-cov-2, to, bat, sars-cov"
61125,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.080808081,"the, have, been, animal, in, to, and, may"
61126,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.080808081,"to, the, of, yunnan, may, spillover, high, bat"
61127,"the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.080808081,"the, to, that, related, sars-cov-2, bat, in, and"
61128,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.080808081,"the, of, to, sars-cov, and, 50%, both, in"
61129,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.080808081,"of, the, to, high, yunnan, bat, spillover, may"
61130,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.080808081,"this, that, in, the, a, and, of, often"
61131,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.080808081,"in, the, of, from, to, species, were, and"
61132,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.080808081,"the, and, of, to, were, in, sars-cov-2, those"
61133,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.080808081,"and, the, to, with, other, that, in, for"
61134,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.080808081,"early, the, of, that, in, this, at, market"
61135,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.080808081,"in, a, of, to, the, closely, related, virus"
61136,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","the coronaviruses discovered to date that are most closely related to SARS-CoV-2 are  

all bat coronaviruses discovered in southern China and Southeast Asia, including Laos, Thailand and  

Cambodia",0.080808081,"sars-cov-2, and, the, to, related, in, that, bat"
61137,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.080808081,"that, and, for, to, other, the, in, with"
61138,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.080808081,"the, to, sars-related, virus, bat, as, by, of"
61139,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.080808081,"at, to, a, from, the, by, of, and"
61140,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.080808081,"the, that, a, virus, in, animal, this, additional"
61141,"More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.080808081,"than, of, the, were, to, and, that, was"
61142,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.080808081,"in, from, species, of, were, to, and, the"
61143,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.080808081,"that, more, than, the, to, in, of, and"
61144,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.080808081,"several, have, that, to, identical, genome, as, the"
61145,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.080808081,"of, the, as, those, in, isolated, from, a"
61146,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.080808081,"the, of, a, prior, as, present, viral, and"
61147,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.080808081,"that, the, with, scale, of, virus, and, to"
61148,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.080808081,"were, at, two, of, from, in, and, to"
61149,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.080808081,"the, virus, which, to, of, and, coronavirus, from"
61150,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.080808081,"of, the, genome, virus, and, other, bat, coronavirus"
61151,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.080808081,"at, a, and, this, in, the, to, sars"
61152,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.080808081,"the, of, more, to, a, bat, genome, than"
61153,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.080808081,"that, the, from, a, live, in, to, and"
61154,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.080808081,"the, of, virus, to, as, by, bat, sars-related"
61155,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.080808081,"to, the, of, from, by, a, virus, with"
61156,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.080808081,"the, of, and, suggesting, an, animal, to, by"
61157,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.080808081,"and, bats,, of, to, an, animal, species, by"
61158,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.080808081,"the, by, from, a, at, and, to, of"
61159,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.080808081,"in, the, of, that, and, this, often, a"
61160,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.080808081,"a, and, with, the, of, virus, in, yunnan"
61161,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.080808081,"a, at, to, that, the, of, sars-cov-2, this"
61162,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.080808081,"in, of, were, to, sars-cov-2, and, the, those"
61163,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.080808081,"the, of, in, market, early, that, this, at"
61164,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.080808081,"that, the, between, sars-cov-2, and, is, than, sars"
61165,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.080808081,"other, that, sars-cov-2, to, and, a, the, of"
61166,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.080808081,"in, a, to, the, this, and, sars, at"
61167,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.080808081,"the, that, to, in, is, its, it, not"
61168,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.080808081,"this, that, a, the, virus, animal, additional, in"
61169,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.080808081,"and, both, of, the, to, in, sars-cov, 50%"
61170,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.080808081,"by, et, al., in, the, to, of, bats"
61171,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.080808081,"of, to, a, have, not, and, ability, the"
61172,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.080808081,"prior, the, as, viral, and, a, of, present"
61173,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.080808081,"in, the, of, that, to, and, more, than"
61174,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.080808081,"bats, the, by, of, to, in, et, al."
61175,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Outcomes of a phylogenetic analysis 

suggest that the virus belongs to the genus Betacoronavirus, sub-genus 

Sarbecovirus, which includes many bat SARS-like CoVs and SARS CoVs.",0.080808081,"the, sars, of, that, virus, to, a, and"
61176,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.080808081,"with, the, and, of, a, that, in, sars-cov-2"
61177,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.080808081,"the, and, that, is, between, sars-cov-2, sars, than"
61178,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.080808081,"the, and, of, a, to, that, sars-cov-2, other"
61179,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.080808081,"a, of, to, the, bat, genome, more, than"
61180,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.080808081,"from, the, to, a, virus, with, by, of"
61181,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.080645161,"viruses, to, in, and, a"
61182,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.080645161,"in, viruses, are, the, sars"
61183,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.080645161,"have, animal, identified, and, coronaviruses"
61184,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.080645161,"of, coronavirus, with, that, bats"
61185,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.080645161,"and, that, bats, or, for"
61186,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.080645161,"and, sars-cov-2, and/or, to, in"
61187,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.080645161,"the, southern, of, china, in"
61188,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.080645161,"the, of, have, to, from"
61189,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.080645161,"the, of, which, may, to"
61190,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.080645161,"and, from, to, human, have"
61191,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.080645161,"to, have, the, of, from"
61192,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.080645161,"between, and, have, the, in"
61193,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.080645161,"the, in, a, laboratory, unlikely"
61194,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.080645161,"the, virus, from, in, 2020"
61195,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.080645161,"is, the, that, by, from"
61196,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.080645161,"of, the, a, to, those"
61197,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.080645161,"and, coronaviruses, bat, to, that"
61198,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.080645161,"sars-cov-2, natural, the, with, to"
61199,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.080645161,"the, reservoir, and, viruses, including"
61200,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.080645161,"of, the, and, are, viruses"
61201,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.080645161,"the, and, to, suggesting, that"
61202,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.080645161,"of, in, similar, that, such"
61203,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.080645161,"sars-cov-2, of, and, with, tion"
61204,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.080645161,"the, that, to, humans, and"
61205,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.080645161,"the, of, in, that, a"
61206,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.080645161,"bats, as, the, of, and"
61207,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.080645161,"the, of, that, use, receptor"
61208,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.080645161,"the, to, of, is, in"
61209,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.080645161,"the, and, from, to, respectively"
61210,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.080645161,"is, from, to, which, in"
61211,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.080645161,"with, the, to, sars-cov-2, is"
61212,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.080645161,"of, the, that, and, with"
61213,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.080645161,"of, the, are, that, for"
61214,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.080645161,"for, the, of, that, sars"
61215,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.080645161,"in, the, that, was, to"
61216,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.080645161,"the, in, with, at, coronaviruses"
61217,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists",0.080645161,"out, had, a, other, the"
61218,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.080645161,"have, identified, animal, coronaviruses, and"
61219,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.080645161,"as, a, host, from, and"
61220,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.080645161,"and, from, bat, that, coronavirus"
61221,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.080645161,"these, and, the, of, that"
61222,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.080645161,"that, of, nucleotide, and, ratg13"
61223,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.080645161,"are, of, a, to, that"
61224,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.080645161,"a, and, b, their, in"
61225,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.080645161,"that, the, zoonotic, and, of"
61226,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.080645161,"the, were, zoonotic, and, a, in, of, from, that, humans"
61227,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.080645161,"we, a, origin, of, genomic"
61228,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.080645161,"we, that, sars-cov-2, the, origin"
61229,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses",0.080645161,"to, other, the, were, in"
61230,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.080645161,"and, the, huanan, market, in"
61231,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.080645161,"a, and, in, b, their"
61232,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.080645161,"sars-cov-2, and, from, to, in"
61233,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.080645161,"unlikely, a, laboratory, the, in"
61234,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.080645161,"unlikely, a, the, of, incident"
61235,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.080645161,"sars-cov-2, and, is, to, that"
61236,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.080645161,"in, that, sars-cov-2, was, to"
61237,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.080645161,"a, in, that, had, or"
61238,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.080645161,"as, the, to, it, that"
61239,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.080645161,"the, that, is, not, in"
61240,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.080645161,"our, that, is, not, a"
61241,"the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.080645161,"the, in, is, and, on"
61242,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.080645161,"is, the, sars-cov-2, we, that"
61243,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.080645161,"that, the, of, to, market"
61244,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.080645161,"that, infected, to, the, for"
61245,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.080645161,"the, of, to, at, that"
61246,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.080645161,"the, of, a, in, with"
61247,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.080645161,"to, the, of, market, that"
61248,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.080645161,"with, that, the, of, and"
61249,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.080645161,"the, to, which, or, of"
61250,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.080645161,"confirmed, the, also, and, to"
61251,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.080645161,"this, in, the, of, to"
61252,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.080645161,"bats, to, that, sars-cov-2, and"
61253,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.080645161,"the, of, spike, and, to"
61254,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.080645161,"can, from, to, of, and"
61255,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.080645161,"of, and, the, to, from"
61256,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","the pangolin is considered to be one of the possible 

intermediate hosts between bat and human",0.080645161,"intermediate, and, to, the, of"
61257,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.080645161,"the, is, by, that, sequences"
61258,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.080645161,"of, the, to, that, animal"
61259,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",0.080645161,"the, and, to, in, virus"
61260,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.080645161,"of, covid-19, exposure, to, the"
61261,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.080645161,"is, and, animals, to, in"
61262,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.080645161,"a, of, the, that, at"
61263,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","respon- 

dents who read the natural origin treatment were more likely to believe  

that the virus started in animals and jumped naturally to humans",0.080645161,"to, and, the, were, in"
61264,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.080645161,"and, the, that, its, in"
61265,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.080645161,"of, the, that, and, zoonotic"
61266,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.080645161,"the, is, intermediate, or, for"
61267,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.080645161,"to, or, be, and, their"
61268,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.080645161,"a, is, the, it, human"
61269,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.080645161,"the, that, could, primary, to"
61270,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.080645161,"be, possible, bat, to, bats"
61271,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.080645161,"of, the, patients, in, with"
61272,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.080645161,"have, the, of, a, as"
61273,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.080645161,"of, that, bats, with, coronavirus"
61274,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.080645161,"the, of, a, that, not"
61275,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.080645161,"that, a, of, with, the"
61276,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)",0.080645161,"the, of, identical, to, human"
61277,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.080645161,"also, the, and, confirmed, to"
61278,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.080645161,"the, of, bat, can, to"
61279,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.080645161,"the, is, used, coronavirus, can"
61280,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.080645161,"bats, the, as, of, and"
61281,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.080645161,"of, to, the, which, or"
61282,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.080645161,"to, and, at, the, which"
61283,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.080645161,"found, with, to, the, for"
61284,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.080645161,"that, the, of, with, and"
61285,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.080645161,"the, bat, of, and, covs"
61286,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.080645161,"the, of, sars-cov-2, that, cov"
61287,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.080645161,"of, the, viruses, in, protein"
61288,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.080645161,"a, to, animal, called, virus"
61289,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.080645161,"and, that, is, natural, sars-cov-2"
61290,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Bioinformatic  

analyses indicated that the virus had features typical of the coronavirus family and belonged  

to the Betacoronavirus 2B lineage",0.080645161,"of, the, lineage, that, and"
61291,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.080645161,"the, coronavirus, of, and, covid-19"
61292,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.080645161,"from, the, virus, in, 2020"
61293,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.080645161,"the, patients, with, in, of"
61294,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation",0.080645161,"in, between, and, 2019, different"
61295,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.080645161,"in, with, and, which, are"
61296,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.080645161,"bats, intermediate, and, the, or"
61297,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.080645161,"the, of, and, that, novel"
61298,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.080645161,"a, from, not, and, on"
61299,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.080645161,"the, and, a, that, not"
61300,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.080645161,"of, the, and, virus, s"
61301,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.080645161,"are, the, of, is, and"
61302,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.080645161,"to, of, sequences, the, that"
61303,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.080645161,"from, a, in, the, that"
61304,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.080645161,"the, of, to, sars-cov-2,, bat"
61305,"coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.080645161,"coronaviruses, that, to, in, and"
61306,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.080645161,"that, the, of, sars-cov-2, he"
61307,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.080645161,"sars-cov-2, of, that, the, for"
61308,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.080645161,"and, bat, coronaviruses, that, to"
61309,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.080645161,"is, to, which, in, from"
61310,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.080645161,"and, that, from, bat, coronavirus"
61311,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.080645161,"is, that, to, a, and"
61312,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.080645161,"is, sars-cov-2, to, a, in"
61313,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.080645161,"between, and, is, a, to"
61314,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.080645161,"a, and, in, that, to"
61315,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.080645161,"that, can, be, in, which"
61316,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.080645161,"to, that, and, is, be"
61317,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.080645161,"that, sars-cov-2, to, a, bat"
61318,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.080645161,"studies, sequences, the, of, and"
61319,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.080645161,"to, the, of, which, may"
61320,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.080645161,"the, of, which, to, that"
61321,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.080645161,"is, a, and, to, that"
61322,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","a coronavirus strain in the Malay pan- 

golin with a genome that was similar to that of SARS-  

CoV-2 at 85.5%–92.4%.",0.080645161,"in, the, that, of, to"
61323,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","SARS-CoV-2 was  

rapidly sequenced (Zhu et al., 2020) and linked to bats CoV belonging to  

the lineage b of betacoronavirus",0.080645161,"the, and, of, linked, to"
61324,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.080645161,"the, have, as, a, of"
61325,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.080645161,"a, of, bats, the, coronaviruses"
61326,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.080645161,"from, host, a, as, and"
61327,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.080645161,"to, sars-cov-2, the, and, been"
61328,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.080645161,"in, to, the, that, is"
61329,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.080645161,"the, in, that, not, is"
61330,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.080645161,"the, that, into, in, to"
61331,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.080645161,"and, the, 2, sars-cov-2, with"
61332,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.080645161,"that, to, sars-cov-2, in, humans"
61333,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.080645161,"the, in, of, rhinolophus, and"
61334,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.080645161,"a, of, found, that, with"
61335,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.080645161,"a, with, sars-cov-2, has, in"
61336,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.080645161,"in, sars-cov-2, with, bat, that"
61337,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.080645161,"to, the, virus, from, market"
61338,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.080645161,"the, from, to, as, and"
61339,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.080645161,"in, the, coronaviruses, at, with"
61340,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.080645161,"from, to, and, the, respectively"
61341,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.080645161,"the, rbd, and, in, is"
61342,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Surpris- 

ingly, the Pangolin-CoV mentioned above possesses the same six key 

RBD residues as SARS-CoV-2 in the RBD, showing closer homology 

with SARS-CoV-2",0.080645161,"in, sars-cov-2, with, the, same"
61343,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.080645161,"these, and, that, the, of"
61344,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.080645161,"the, that, as, it, to"
61345,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.",0.080645161,"therefore,, sars-cov-2, is, to, the"
61346,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.080645161,"the, pangolins, with, and, sars-cov-2"
61347,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.080645161,"the, to, that, in, with"
61348,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.080645161,"the, sars-cov-2, in, pangolins, and"
61349,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.080645161,"to, that, sars-cov-2, the, be"
61350,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.080645161,"the, to, and, suggesting, that"
61351,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2",0.080645161,"and, a, to, that, in"
61352,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.080645161,"the, zoonotic, spillover, from, a"
61353,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.080645161,"the, and, to, a, of"
61354,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.080645161,"evidence, that, the, of, and"
61355,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.080645161,"the, to, of, in, human"
61356,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","Positive environmental samples from the market from  

the western section that traded wildlife/animal products  

implicating the presence of racoon dogs in proximity of  

environmental samples positive for SARS-CoV-2",0.080645161,"for, the, of, in, that"
61357,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.080645161,"to, been, and, the, sars-cov-2"
61358,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.080645161,"the, a, of, incident, unlikely"
61359,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.080645161,"sars-cov-2, is, a, to, in"
61360,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.080645161,"the, reservoir, including, and, viruses"
61361,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans",0.080645161,"the, and, other, viruses, to"
61362,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.080645161,"of, animal, for, sars, the"
61363,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.080645161,"the, to, and, viruses, other"
61364,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.080645161,"the, and, other, viruses, sars"
61365,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","Bat population density and species variety appear to play an important role  

in shaping the evolution of SARS-related coronaviruses.",0.080645161,"in, the, and, of, to"
61366,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.080645161,"of, the, in, a, similar"
61367,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.080645161,"the, of, to, bat, can"
61368,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.080645161,"the, as, to, by, bat"
61369,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.080645161,"are, and, which, in, with"
61370,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.080645161,"sars-cov-2, the, and, in, related"
61371,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.080645161,"and, the, are, sars-cov-2, with"
61372,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.080645161,"in, a, sars-cov-2, to, with"
61373,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.080645161,"are, and, that, the, is"
61374,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.080645161,"the, that, of, to, through"
61375,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.",0.080645161,"in, the, of, from, more"
61376,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.080645161,"the, to, at, which, and"
61377,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.080645161,"animal, to, a, and, in"
61378,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.080645161,"the, of, bat, to, sars-cov-2,"
61379,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.080645161,"virus, bat, to, of, as"
61380,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.080645161,"the, to, bat, of, sars-cov-2,"
61381,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.080645161,"of, the, origins, covid-19, approximately"
61382,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.080645161,"the, of, with, that, and"
61383,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.080645161,"that, a, found, of, with"
61384,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.080645161,"of, at, the, a, to"
61385,"There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.080645161,"that, had, or, a, in"
61386,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.080645161,"the, animal, for, of, sars"
61387,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.080645161,"of, the, sars, that, for"
61388,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.080645161,"into, the, that, in, to"
61389,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.080645161,"in, were, to, humans, intermediate"
61390,"0.001. This again indicates 

that bats are the more likely origin of SARS-CoV-2 than pa","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.080645161,"this, that, the, likely, of"
61391,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.080645161,"in, a, of, for, were, found, to, infected, with, that"
61392,"he BANAL series is also more divergent from SARS-CoV- 

2 in the S2 subunit of the spike protein.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.080645161,"more, from, in, the, of"
61393,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.080645161,"the, of, identical, and, to"
61394,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.080645161,"a, of, the, from, that, and, zoonotic, in, were, humans"
61395,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.080645161,"and, the, it, that, or, for, of, in, a, by"
61396,"WHO report did not consider a hypothesis that the virus  

was released intentionally, stating that it had been ruled out  

by other scientists","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.080645161,"a, the, had, out, other"
61397,"These re- 

peated introductions were easily identifiable 

because human viruses in these outbreaks were 

more closely related to viruses sampled in the 

animal reservoirs than to other human viruses","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.080645161,"were, in, to, the, other"
61398,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.080645161,"the, huanan, market, in, and"
61399,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.080645161,"the, of, covid-19, exposure, to"
61400,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.080645161,"of, covid-19, to, the, and"
61401,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.080645161,"the, of, a, history, and"
61402,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.080645161,"is, a, between, and, to"
61403,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.080645161,"a, and, to, that, in"
61404,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.080645161,"in, are, to, that, and"
61405,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.080645161,"and, of, is, that, in"
61406,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.080645161,"the, and, that, its, in"
61407,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.080645161,"the, a, zoonotic, spillover, from"
61408,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.080645161,"by, the, of, a, in, that, and, or, it, for"
61409,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market",0.080645161,"the, all, from, collected, in"
61410,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.080645161,"to, for, the, infected, that"
61411,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.080645161,"the, found, to, with, for"
61412,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.080645161,"and, coronaviruses, that, in, to"
61413,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.080645161,"and, in, to, that, coronaviruses"
61414,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.080645161,"a, and, sars-cov-2, has, in"
61415,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.080645161,"the, genomic, in, that, a"
61416,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.080645161,"a, our, that, not, is"
61417,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.",0.080645161,"not, that, sars-cov-2, a, laboratory"
61418,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.080645161,"a, of, the, that, not"
61419,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.080645161,"a, on, to, of, the"
61420,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.080645161,"a, the, is, it, human"
61421,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.080645161,"the, that, ace2, in, this"
61422,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.080645161,"and, sars-cov-2, pangolins, the, with"
61423,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.080645161,"the, and, in, rbd, is"
61424,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.080645161,"in, related, and, sars-cov-2, the"
61425,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.080645161,"to, have, and, from, human"
61426,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.080645161,"in, animals, to, is, and"
61427,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.080645161,"in, the, a, coronavirus, that"
61428,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.080645161,"in, the, this, that, ace2"
61429,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.080645161,"to, and, the, spike, of"
61430,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.080645161,"that, to, could, the, primary"
61431,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.080645161,"the, of, in, and, than"
61432,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.080645161,"the, and, to, sars-, analysis"
61433,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.080645161,"the, is, or, intermediate, for"
61434,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.080645161,"virus, to, bats, of, and"
61435,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.080645161,"of, and, the, to, through"
61436,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.",0.080645161,"were, intermediate, in, humans, to"
61437,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.080645161,"in, the, by, that, of"
61438,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.080645161,"of, covid-19, to, and, the"
61439,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.080645161,"and, to, in, a, viruses"
61440,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.080645161,"of, the, covid-19, and, coronavirus"
61441,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.080645161,"the, of, rhinolophus, and, in"
61442,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.080645161,"been, suggesting, that, and, a"
61443,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.080645161,"to, have, in, the, pangolin,"
61444,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.080645161,"that, the, of, evidence, and"
61445,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.080645161,"can, be, which, that, in"
61446,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.080645161,"that, was, the, of, to"
61447,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.080645161,"in, of, that, the, with"
61448,"builds on evidence presented in the WHO-China Joint Report and the leaked January  

22 CCDC report showing that 90% of the positive environmental samples collected on January 1 and 12,  

2020 were linked to vendors on the western side of the Huanan market. That 87.5% of all positive  

environmental samples were taken from the western half of the market. In total, 71.4% of all positive  

environmental samples located between rows 1 through 8 in the south-western section of the market","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.080645161,"in, the, collected, all, from"
61449,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.080645161,"to, and, their, or, be"
61450,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.080645161,"to, from, and, can, of"
61451,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.080645161,"to, bat, bats, be, possible"
61452,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.080645161,"on, and, not, from, a"
61453,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.080645161,"of, virus, to, as, bat"
61454,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.080645161,"virus, bats, and, to, of"
61455,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.080645161,"the, in, of, southern, china"
61456,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.080645161,"virus, animal, to, a, called"
61457,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.080645161,"sars-cov-2, in, of, and, the"
61458,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.080645161,"and, sars-cov-2, pangolins, the, in"
61459,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.080645161,"in, different, between, 2019, and"
61460,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.080645161,"the, between, and, have, in"
61461,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.080645161,"and, the, bats, or, intermediate"
61462,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.080645161,"the, and, that, is, of"
61463,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","this indicates a strong suspicion that the 

Covid-19 outbreak is a consequence of illegal trade and 

consumption of wild animals",0.080645161,"and, that, the, of, is"
61464,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.080645161,"the, and, to, through, of"
61465,"he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.080645161,"bat, to, as, by, the"
61466,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor",0.080645161,"been, and, suggesting, that, a"
61467,"SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.080645161,"and, sars-cov-2, in, to, and/or"
61468,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.080645161,"a, in, has, with, sars-cov-2"
61469,"It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.080645161,"the, hosts, sars-cov-2, to, a"
61470,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","the disease in bats is generally asymptomatic 

and very little information is available on associated lesions,",0.080645161,"the, and, in, on, is"
61471,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)",0.080645161,"of, many, and, such, as"
61472,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus",0.080645161,"the, of, a, that, virus"
61473,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.080645161,"the, of, virus, to, and"
61474,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.080645161,"a, origin, of, we, genomic"
61475,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.080645161,"the, could, of, with, or"
61476,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.080645161,"that, to, humans, in, sars-cov-2"
61477,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.080645161,"the, to, of, intermediate, and"
61478,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.080645161,"hypothesis, the, of, that, sars-cov-2"
61479,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.080645161,"of, a, history, and, the"
61480,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.080645161,"of, natural, the, and, ability"
61481,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.080645161,"by, a, pangolin, ratg13,, the"
61482,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.080645161,"that, bats, and, are, of"
61483,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.080645161,"nucleotide, and, that, ratg13, of"
61484,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.080645161,"to, sars-cov-2, that, bats, and"
61485,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.080645161,"are, and, in, that, to"
61486,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.080645161,"sars-cov-2, to, in, ratg13, which"
61487,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.080645161,"with, sars-cov-2, of, bat, ratg13"
61488,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.080645161,"is, that, from, by, the"
61489,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.080645161,"with, the, to, sars-cov-2, of"
61490,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.080645161,"the, sequences, that, is, by"
61491,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.080645161,"the, coronavirus, is, used, can"
61492,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.080645161,"is, and, be, to, that"
61493,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","It is believed that bats are the most likely reservoir hosts for 

SARS-CoV-2 as it is very similar to a bat coronavirus.",0.080645161,"a, sars-cov-2, hosts, to, the"
61494,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.080645161,"the, a, in, bat, of"
61495,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.",0.080645161,"and, the, 2, sars-cov-2, ratg13"
61496,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2",0.080645161,"a, the, ratg13,, by, pangolin"
61497,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.080645161,"and, that, the, novel, of"
61498,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.080645161,"a, that, genomic, the, in"
61499,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.080645161,"the, of, than, and, in"
61500,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa",0.080645161,"of, and, a, that, in"
61501,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.080645161,"the, sars, and, other, viruses"
61502,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.080645161,"and, that, bats, for, or"
61503,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.080645161,"that, the, sars-cov-2, is, we"
61504,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.080645161,"the, of, and, that, viruses"
61505,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.080645161,"the, of, that, viruses, and"
61506,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.080645161,"the, and, has, that, of"
61507,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.080645161,"the, sars, are, viruses, in"
61508,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.080645161,"that, bat, in, with, sars-cov-2"
61509,"The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.080645161,"the, and, are, is, that"
61510,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.080645161,"the, to, therefore,, sars-cov-2, is"
61511,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.080645161,"to, the, have, in, pangolin,"
61512,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.080645161,"in, which, to, sars-cov-2, ratg13"
61513,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.080645161,"of, bat, with, sars-cov-2, ratg13"
61514,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol",0.080645161,"bats, are, hosts, that, in"
61515,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.080645161,"origin, the, we, that, sars-cov-2"
61516,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.080645161,"the, 2, sars-cov-2, with, and"
61517,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.080645161,"with, and, are, sars-cov-2, the"
61518,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.080645161,"and, sars-cov-2, ratg13, the, 2"
61519,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.080645161,"bat, covs, the, of, and"
61520,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.080645161,"studies, the, sequences, of, and"
61521,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,",0.080645161,"sars-cov-2, a, bat, to, that"
61522,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.080645161,"the, of, identical, to, and"
61523,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.080645161,"in, the, of, that, and"
61524,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","the critical residues binding to hACE2 are 100%  

identical in SARS-CoV-2 and Pangolin-CoV",0.080645161,"the, to, in, and, identical"
61525,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.080645161,"the, of, and, with, at"
61526,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.080645161,"cov, that, the, of, sars-cov-2"
61527,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.080645161,"the, and, sars-cov-2, of, bat"
61528,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Whereas, another study  

suggested bat might be the original host of SARS-CoV-2 and an unknown  

animal might present an intermediate host",0.080645161,"and, be, the, of, sars-cov-2"
61529,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.080645161,"in, a, with, to, sars-cov-2"
61530,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.080645161,"a, of, were, in, to, with, infected, for, found, that"
61531,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.080645161,"a, are, to, that, of"
61532,"A study reported that the beta variant 

was able to infect common BALB/c laboratory mice and caused pul- 

monary changes in contrast to WT SARS-CoV-2","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.080645161,"a, that, to, and, in"
61533,"BCoV is an ancestor of many other coronaviruses affecting other species, such as humans 

(HCoV-OC43), swine (Porcine Hemagglutinating Encephalomyelitis virus—PHEV), equids (ECoV), 

and dogs (CRCoV)","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.080645161,"of, many, such, as, and"
61534,"e. 

Results of the two clustering methods presented in Figs. 3 and 4 

show that SARS-CoV-2 sequences form a group with viruses in the 

Coronaviridae fa","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.080645161,"of, in, and, that, a"
61535,"TG13. This further confirms our findings 

when using the hierarchical clustering in Fig. 7 that bats are more 

likely the hosts for the SARS-CoV-2 than pangol","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.080645161,"in, that, bats, are, hosts"
61536,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.080645161,"to, those, of, the, a"
61537,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.080645161,"that, similar, of, in, such"
61538,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.080645161,"the, of, that, animal, to"
61539,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.080645161,"the, a, at, to, of"
61540,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.080645161,"the, that, and, not, a"
61541,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.080645161,"that, the, of, and, has"
61542,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.080645161,"is, that, of, and, in"
61543,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.080645161,"of, in, similar, to, that"
61544,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.080645161,"of, the, to, sars-, cov-2"
61545,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.080645161,"of, sars-cov-2, and, with, tion"
61546,"he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.080645161,"of, the, protein, in, viruses"
61547,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.080645161,"of, the, virus, and, s"
61548,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.080645161,"the, analysis, to, sars-, and"
61549,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.080645161,"the, of, natural, ability, and"
61550,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.08045977,"he, that, of, sars-cov-2, the, which, for"
61551,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.08045977,"the, ability, of, sars-cov-2, to, for, and"
61552,"The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.08045977,"the, of, a, and, sars-cov-2, via, or"
61553,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.08045977,"of, the, sars-cov-2, have, in, origin, and"
61554,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.08045977,"an, to, a, animal, the, of, and"
61555,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.08045977,"in, the, and, at, are, to, for"
61556,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.08045977,"that, are, the, to, with, in, and"
61557,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.08045977,"of, a, early, and, the, were, in"
61558,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.08045977,"sars-cov-2, of, the, and, zoonotic, viruses, in"
61559,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.08045977,"that, in, the, market, at, and, animal"
61560,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.08045977,"the, of, market, in, live, animals, a"
61561,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.08045977,"that, the, sars-cov-2, to, may, in, of"
61562,"This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.08045977,"this, that, natural, might, the, for, of"
61563,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.08045977,"that, in, was, to, not, do, other"
61564,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.08045977,"in, the, are, to, at, and, for"
61565,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.08045977,"of, the, at, are, other, to, virus"
61566,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.08045977,"on, the, could, be, infected, by, as"
61567,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.08045977,"the, of, that, a, in, are, to"
61568,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.08045977,"the, a, in, to, that, are, of"
61569,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.08045977,"that, of, is, a, found, in, the"
61570,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.08045977,"but, a, virus, not, of, and, on"
61571,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.08045977,"not, a, of, but, and, the, animals"
61572,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.08045977,"that, other, do, not, was, to, in"
61573,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.08045977,"the, animals, is, that, virus, were, and"
61574,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program",0.08045977,"at, a, as, the, virus, all, of"
61575,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.08045977,"among, the, with, high, of, natural, and"
61576,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.08045977,"the, bat, to, related, bats, that, is"
61577,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat",0.08045977,"the, is, that, have, of, to, and"
61578,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","he critical func- 

tional regions of the spike protein SAR-CoV-2 are nearly the same as 

those defined in viruses isolated from a pangolin",0.08045977,"from, in, the, a, of, are, viruses"
61579,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.08045977,"sars, the, of, in, also, isolated, to"
61580,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.08045977,"the, of, a, to, and, sars-cov, palm"
61581,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.08045977,"in, a, of, to, the, are, that"
61582,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.08045977,"the, are, to, of, most, likely, bats"
61583,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.08045977,"he, sars-cov-2, of, which, for, that, the"
61584,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.08045977,"in, the, of, an, at, found, and"
61585,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.08045977,"and, the, of, a, that, in, for"
61586,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.08045977,"a, the, of, in, found, that, is"
61587,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","bats are also important reservoir species for a great 

range of coronaviruses",0.08045977,"of, a, species, bats, also, for, coronaviruses"
61588,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.08045977,"sars-cov-2, of, for, to, and, ability, the"
61589,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.08045977,"and, the, of, bat, to, as, bats"
61590,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.08045977,"that, is, related, to, bat, bats, the"
61591,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.08045977,"the, bats, to, as, of, bat, and"
61592,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.08045977,"that, the, of, and, this, viruses, bats"
61593,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.08045977,"the, of, that, a, in, similar, to"
61594,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.08045977,"the, of, that, in, a, sars, to"
61595,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.08045977,"was, first, as, and, in, july, isolated"
61596,"ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.08045977,"the, of, sars, in, also, to, isolated"
61597,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.08045977,"in, the, of, and, an, found, at"
61598,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.08045977,"the, of, in, and, that, than, a"
61599,"bats are also important reservoir species for a great 

range of coronaviruses","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.08045977,"bats, also, species, for, a, of, coronaviruses"
61600,"t was first  

isolated in bats and designated as BtCoV4991 in July 2013","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.08045977,"was, first, isolated, in, and, as, july"
61601,"there is absolutely no evidence at all that the virus  

was engineered as part of a weapons program","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.08045977,"at, all, the, virus, as, of, a"
61602,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.08045977,"the, animal, at, market, that, in, and"
61603,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.08045977,"bats, are, to, the, most, likely, of"
61604,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.08045977,"in, yunnan, was, to, that, of, the"
61605,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.08045977,"have, the, and, of, is, to, that"
61606,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.08045977,"a, is, to, in, the, that, not"
61607,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.08045977,"a, of, the, early, and, in, were"
61608,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.08045977,"the, of, study, that, in, a, and"
61609,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.08045977,"the, is, that, in, to, a, not"
61610,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.08045977,"sars-cov-2, of, via, a, or, and, the"
61611,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.08045977,"the, of, in, a, to, sars, that"
61612,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.08045977,"and, the, that, of, in, study, a"
61613,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.08045977,"a, of, and, on, virus, not, but"
61614,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.08045977,"from, as, and, to, not, of, a"
61615,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.08045977,"the, on, could, be, infected, as, by"
61616,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.08045977,"sars-cov, and, a, to, the, of, palm"
61617,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.08045977,"sars-cov-2, origin, of, have, in, and, the"
61618,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.08045977,"a, the, of, and, animals, not, but"
61619,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.08045977,"the, of, at, are, to, other, virus"
61620,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.08045977,"that, are, the, to, by, of, origin"
61621,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.08045977,"a, from, to, not, of, and, as"
61622,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.08045977,"in, the, of, that, sars-cov-2, may, to"
61623,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.08045977,"the, natural, of, among, high, and, with"
61624,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.08045977,"of, the, are, by, that, to, origin"
61625,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.08045977,"in, the, of, a, that, and, than"
61626,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.08045977,"and, the, of, viruses, bats, that, this"
61627,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.08045977,"that, this, the, of, might, for, natural"
61628,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.08045977,"the, of, to, a, with, recombination, virus"
61629,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.08045977,"the, to, in, of, was, that, yunnan"
61630,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV",0.080357143,"the, of, a, to, bat, found, genome, that, it"
61631,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.080357143,"and, the, to, animals, in, with, that, for, coronavirus"
61632,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.080357143,"for, and, to, at, the, in, of, there, no"
61633,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.080357143,"the, by, of, mutations, in, and, that, coronavirus, than"
61634,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.080357143,"the, of, that, was, to, a, is, and, evidence"
61635,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.080357143,"the, and, of, a, to, that, is, sars-cov-2, likely"
61636,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.080357143,"the, a, to, on, bat, as, with, and, that"
61637,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.080357143,"the, of, to, bats, with, as, and, or, for"
61638,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.080357143,"a, of, to, coronaviruses, the, bats, coronavirus, novel, and"
61639,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.080357143,"the, a, that, ace2, as, receptor, and, of, at"
61640,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.080357143,"a, the, were, in, it, with, for, intermediate, host"
61641,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.080357143,"in, the, coronavirus, that, animals, to, and, with, for"
61642,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.080357143,"to, that, the, of, and, may, have, for, sars-cov-2"
61643,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.080357143,"suggested, that, a, the, pre-existing, with, of, in, to"
61644,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.080357143,"to, a, of, pre-existing, in, the, suggested, that, with"
61645,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.080357143,"that, a, was, the, of, and, evidence, is, to"
61646,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.080357143,"were, a, intermediate, host, for, it, with, the, in"
61647,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.080357143,"bats, as, the, to, or, with, of, for, and"
61648,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.080357143,"coronaviruses, and, a, novel, to, the, coronavirus, bats, of"
61649,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.080357143,"the, identified, a, of, most, from, to, bat, and"
61650,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.080357143,"that, the, of, and, at, receptor, ace2, as, a"
61651,"t was 

found that the genome sequence of SARS-CoV-2 is 

96.2% identical to a bat CoV RaTG13, whereas it shares 

79.5% identity to SARS-CoV","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.080357143,"found, that, the, genome, of, to, a, bat, it"
61652,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.080357143,"on, the, as, a, that, with, bat, and, to"
61653,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.080357143,"and, from, in, were, that, the, of, bats, are"
61654,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.080357143,"in, the, of, and, at, to, for, there, no"
61655,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.080357143,"that, a, likely, the, of, sars-cov-2, and, is, to"
61656,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.080357143,"a, of, to, the, from, identified, bat, most, and"
61657,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.080357143,"the, that, coronavirus, in, by, than, mutations, of, and"
61658,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.080357143,"sars-cov-2, and, of, the, have, to, that, for, may"
61659,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.080357143,"that, were, from, bats, in, the, and, of, are"
61660,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.080291971,"in, after, the, of, that, for, did, virus, to, a, and"
61661,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.080291971,"the, and, for, of, a, or, to, that, covid-19, in, sars-cov-2"
61662,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.080291971,"of, for, to, a, virus, that, did, after, in, and, the"
61663,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.080291971,"sars-cov-2, of, covid-19, for, to, a, or, that, in, and, the"
61664,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","n 2007, scientists studying coronaviruses warned: “The 

presence of a large reservoir of SARS-CoV–like viruses in 

horseshoe bats",0.08,"in, a, presence, of"
61665,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.08,"bats, the, of, pangolins"
61666,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.",0.08,"pangolins, a, the, in"
61667,"Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.08,"in, to, a, and"
61668,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.08,"of, the, virus, this, from, wild"
61669,"On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.08,"the, natural, and, from"
61670,"pidemiologic studies indicated that the  

outbreak started from a seafood market selling live  

animals in Wuhan, China; subsequently transmitted  

to humans and further spread from person-to-person","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.08,"the, from, humans, and"
61671,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.08,"the, and, within, of"
61672,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.08,"and, the, of, into, this, from"
61673,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans",0.08,"from, into, and, this, the, of"
61674,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.08,"are, in, the, bats"
61675,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats",0.08,"the, from, as, or"
61676,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.08,"the, have, animal, and"
61677,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.08,"the, of, most, location"
61678,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences",0.08,"the, global, also, most"
61679,"The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.08,"of, with, that, and"
61680,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.08,"that, virus, of, with"
61681,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.",0.08,"bat, and, genetic, sars-cov"
61682,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.08,"of, and, sars-cov-2, in"
61683,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.08,"of, which, to, and"
61684,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","SARS-CoV and SARS-CoV-2 emerged in China, home to 

bats of more than 100 species, many of which carry α- and/or 

β-coronaviruses",0.08,"of, to, and, sars-cov-2"
61685,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.08,"genetic, of, sequences, from"
61686,Bats are hosts of many coronaviruses,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",0.08,"are, many"
61687,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","One such virus is more than 96% identical to 

SARS-CoV-2 in its whole genome",0.08,"96%, sars-cov-2"
61688,"a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.08,"a, nature"
61689,"the pangolin is considered to be one of the possible 

intermediate hosts between bat and human","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.08,"is, and"
61690,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.08,"coronavirus, nature"
61691,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution",0.08,"and, for"
61692,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.08,"also, the"
61693,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.08,"in, bats, are, of"
61694,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.08,"bat, virus, of, with"
61695,"naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV","SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses",0.08,"have, been, of, coronaviruses"
61696,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.08,"coronavirus, from"
61697,"virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.08,"is, from"
61698,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","ARS-CoV-2 is 

unlike any previously identified coronavirus from which it 

could have been engineered",0.08,"from, is"
61699,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.08,"a, the, has, to, have, sars-cov-2"
61700,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.08,"sars-cov-2, a, virus, the, and, an"
61701,"several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.08,"have, spike, to, sars-cov-2"
61702,"The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.08,"the, of, furin-cleavage, in"
61703,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.08,"to, a, the, viral"
61704,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.08,"groups, and, of, coronaviruses"
61705,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host",0.08,"to, the, that, identified"
61706,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.08,"host, of, and, bat"
61707,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.08,"the, was, and, that"
61708,"After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.08,"the, virus, to, bat"
61709,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.08,"and, to, was, the, that, sars-cov-2"
61710,"In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.08,"in, of, that, as"
61711,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.08,"that, in, which, and"
61712,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.08,"phylogenetic, that, of, and"
61713,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers",0.08,"of, patients, sars-cov-2, with"
61714,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,",0.08,"of, most"
61715,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.08,"that, of, in, as"
61716,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.08,"the, of, human, used"
61717,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.08,"human, the, in, of"
61718,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.08,"in, the, has, as"
61719,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","In the case of COVID-19, the 

ecosystem alteration that has favored its grand scale awakening as 

a dangerous human pathogen has used bats as essential mediators.",0.08,"of, a, in, the"
61720,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.08,"the, a, bats,, and"
61721,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.",0.08,"to, the, and, a, in, had, sequence, that"
61722,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible",0.08,"the, sars-cov-2, for, to"
61723,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.08,"and, the, wuhan, of"
61724,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.08,"the, in, as, point"
61725,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.08,"the, and, what, of"
61726,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.08,"were, to, that, this"
61727,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.08,"the, likely, of, in"
61728,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.08,"in, to, and, a"
61729,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.08,"in, a, and, to"
61730,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.08,"in, china, and, were"
61731,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China",0.08,"and, a, in, to"
61732,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.08,"the, is, coronavirus, a"
61733,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV",0.08,"and, be, may, bats"
61734,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","Bats are 

undoubtedly important and the major natural reservoirs of 

alpha-coronaviruses and beta-coronaviruses",0.08,"bats, of, and, are"
61735,"the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.08,"the, that, and, mers-cov"
61736,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.08,"that, species, to, and"
61737,"the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.08,"the, natural, as, and"
61738,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","SARS-CoV-2 sequenced at the early stage of the 

COVID-19 outbreak only shares 79.6% sequence identity with 

SARS-CoV through early full-length genomic comparisons",0.08,"of, with, the, sars-cov-2"
61739,"This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.08,"to, the, in, which"
61740,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.08,"over, in, is, the"
61741,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan",0.08,"is, to, the, over"
61742,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",Bats are likely reservoir hosts for SARS-CoV-2,0.08,"reservoir, sars-cov-2"
61743,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",Bats are likely reservoir hosts for SARS-CoV-2,0.08,"are, for"
61744,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",zoonotic origins of SARS-CoV-2 by natural evolution,0.08,"of, origins"
61745,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.08,"the, of, and, into"
61746,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases",0.08,"to, other, of, and"
61747,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.08,"was, the, and, to"
61748,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.08,"in, the, and, to"
61749,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions",0.08,"the, to, and, in, sars-cov, other"
61750,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","The phyloge- 

netic analysis shows that SARS-CoV-2 protein is frmly  

rooted in the β-genus lineage of bat coronaviruse",0.08,"the, of, bat, is"
61751,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.08,"of, and, that, with"
61752,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.08,"for, the, of, that"
61753,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.08,"bats, the, of, for"
61754,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.08,"that, the, of, viral"
61755,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.08,"a, the, with, at, was, health, and, to"
61756,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.08,"the, that, from, any"
61757,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","with the first case being linked to  

a seafood market",0.08,"the, market"
61758,"Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure","with the first case being linked to  

a seafood market",0.08,"a, the, seafood, with, market, to"
61759,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","with the first case being linked to  

a seafood market",0.08,"to, a, the, with"
61760,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.08,"bats, found, to, this"
61761,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.08,"the, of, evidence, to"
61762,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.08,"in, of, to, the, from, bats, identified, this"
61763,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found",0.08,"the, of, humans, is"
61764,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.08,"that, a, the, and"
61765,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.08,"that, and, the, in"
61766,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.08,"in, the, and, that"
61767,"The genome of the SARS-CoV-2 has been reported over 80% 

identical to the previous human coronavirus (SARS-like bat CoV)","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.08,"sars-cov-2, has, been, to"
61768,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.08,"to, sars-cov-2, and, at"
61769,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.08,"sars-cov-2, a, animal, and"
61770,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.08,"from, in, south, china, a, and, animal, are"
61771,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.08,"sars-cov-2, and, high, to, in, genetic"
61772,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.08,"a, to, of, the"
61773,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.08,"to, the, evidence, that"
61774,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.08,"and, that, sars-cov-2, through"
61775,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.08,"the, natural, genome, and"
61776,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome",0.08,"the, sars-cov-2, has, and"
61777,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.08,"wuhan, the, of, and"
61778,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.08,"and, have, at, the"
61779,"Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.08,"into, the"
61780,"Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely","hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people",0.08,"the, hypothesis"
61781,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.08,"from, with"
61782,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”","s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events",0.08,"zoonotic, from"
61783,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.08,"related, of, sampled, and"
61784,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.08,"the, of, at, are, to, viruses"
61785,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.08,"the, that, a, this"
61786,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.08,"and, the, origin, are, into, sars-cov-2"
61787,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.08,"of, for, sars-cov-2, zoonotic"
61788,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","In a related study (39), we show that the 

two earliest lineage A cases are more closely 

positioned geographically to the Huanan 

market",0.08,"the, study, that, to"
61789,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","he presence of lineage A virus at the Huanan 

market was confirmed by Gao et al. (43) from a 

sample taken from discarded gloves.",0.08,"of, the, virus, from"
61790,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.08,"of, from, in, and"
61791,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.08,"the, of, and, been"
61792,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.08,"the, result, of, in"
61793,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","the genomic diversity within the 

putative SARS-CoV-2 animal reservoir at the 

Huanan market was likely shallower than that 

seen in SARS-CoV-1 and MERS-CoV reservoirs",0.08,"that, and, mers-cov, the"
61794,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.08,"and, in, of, from"
61795,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.08,"two, to, and, at"
61796,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.08,"to, a, as, in, the, zoonotic, of, and"
61797,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.08,"in, the, and, to, of, as"
61798,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.08,"and, in, to, the, of, very"
61799,"Most genomic encoded proteins of 

SARS-CoV-2 are similar to SARS-CoVs,","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.08,"most, of"
61800,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.08,"identified, the, of, most"
61801,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.",0.08,"of, the, or, scientific"
61802,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.08,"that, the, of, was, to, were"
61803,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.08,"a, from, animals, the"
61804,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.08,"in, the, of, chinese, and, an"
61805,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.08,"the, for, has, a, of, to, that, coronavirus"
61806,"All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.08,"to, in, and, used"
61807,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.08,"from, to, it, is"
61808,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.08,"that, sars-cov-2, is, virus."
61809,"The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.08,"sars-cov-2, is, and, to"
61810,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.08,"viruses, are, at, to, the, of"
61811,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.08,"the, in, of, to, we, virus"
61812,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.08,"of, the, and, are, other, such, as, viruses"
61813,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.08,"other, are, to, and, the, of"
61814,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.08,"the, to, be, sars-cov-2,, in, of"
61815,"they were 

contaminated by bats in the wild in their native Southeast 

Asian forests.","There is zero evidence that WIV 

had SARS-CoV-2 or a progenitor in their collection",0.08,"in, their"
61816,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.08,"of, and, viruses, are, by, different, in, the"
61817,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.08,"to, the, sars, known, and, not, in, of, across, that, have, or"
61818,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.08,"at, the, on, animals, that, were"
61819,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.08,"infected, with, the, sars-cov-2"
61820,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.08,"as, before, by, the, that, sars-cov-2"
61821,"Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.08,"sars-cov-2, by, at, the"
61822,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.08,"the, point, in, as"
61823,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.08,"two, to, a, the"
61824,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.08,"the, a, in, to, that, as, following, it"
61825,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.08,"genome, from, in, the"
61826,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.08,"from, of, wild, this, the, virus"
61827,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.08,"that, of, from, the, wild, for"
61828,"Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.08,"of, the, have, in, from, is"
61829,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.08,"the, on, animals, that, were, at"
61830,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.08,"that, the, virus, but, of, we"
61831,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.08,"to, in, evidence, that"
61832,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.08,"of, and, a, to, that, cause"
61833,"(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.08,"that, was, in, were, a, market"
61834,"In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.08,"in, of, were, to, support, the"
61835,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.08,"other, that, to, a, the, of"
61836,"provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.08,"evidence, supporting, that, for"
61837,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.",0.08,"at, market, that, the, to, of"
61838,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.08,"the, coronavirus, to, bat"
61839,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.08,"virus, with, the, on"
61840,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Samples that were taken from the Huanan seafood market’s objects and animals  

were also positive, indicating that this virus is generated from seafood",0.08,"and, also, is, the"
61841,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.08,"that, to, and, species"
61842,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.08,"have, and, to, of"
61843,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.08,"and, have, they, all"
61844,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.",0.08,"and, have, that, which"
61845,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","In the case of SARS-CoV, the 

horseshoe bat, member of the Rhinolophidae family, was 

considered the natural host and principal reservoir.5",0.08,"in, the, of, family,"
61846,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.08,"to, studies, the, and"
61847,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.08,"the, that, was, to"
61848,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.08,"as, the, of, to"
61849,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.",0.08,"the, of, family,, intermediate"
61850,"Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.08,"nature, a"
61851,"ARS-CoV-2 

has been analyzed throughout genome sequencing, showing 96.2% overall genome sequence identity 

with Bat CoV RaTG13, suggesting that Bat CoV and human SARS-CoV-2 might share a common 

ancestor","Worobey indicates that the majority 

of the cases were grouped in the center of Wuhan, close to 

the westerns shore of the Yangtze river, with a high density 

of homes near and around the Huanan market",0.08,"with, that, and, a"
61852,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.08,"to, virus, that, the"
61853,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.08,"the, in, with, by"
61854,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.08,"the, other, of, in, and, this"
61855,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.08,"bats, the, as, and"
61856,"some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.08,"sars-cov-2, from, and, as"
61857,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.08,"that, to, the, coronavirus, a, of, has, for"
61858,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.08,"and, with, bat, pangolin, that, the"
61859,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.08,"sars-cov-2, has, to, a, have, the"
61860,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.08,"sars-cov-2, a, the, with"
61861,"external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.08,"identity, with"
61862,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.08,"sars-cov-2, from, bat, coronavirus"
61863,"It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus","Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2",0.08,"sars-cov-2, coronavirus"
61864,"all CoV that affect human beings 

have their origin in different animals, which in turn can 

infect other domestic animals and from there infect human 

beings.","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.08,"that, have, which, and"
61865,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.08,"that, sars-cov-2, to, an"
61866,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.08,"to, have, from, a"
61867,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China",0.08,"the, to, that, bats"
61868,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.08,"the, zoonotic, to, of"
61869,COVID-19 is a zoonotic virus,"Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.08,"covid-19, zoonotic"
61870,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Individuals may learn about the origins of COVID-19 through  

exposure to stories that communicate either what most scientists believe (i.e.,  

zoonotic transmission)",0.08,"the, believe, that, of"
61871,"However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.08,"the, and, but, in"
61872,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.08,"virus, in, has, of"
61873,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.08,"has, and, was, in"
61874,"he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.08,"of, has, but, the"
61875,"Our  

analyses clearly show that SARS-CoV-2 is  

not a laboratory construct or a purposefully  

manipulated virus.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.08,"show, that"
61876,"However, in most cases, these viruses were 

transmitted to humans through an intermediate animal host.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.08,"in, to"
61877,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","genetic sequencing has been used to show that  

COVID-19 exists in bats,",0.08,"has, in, to, that"
61878,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.08,"that, the, and, sars-cov"
61879,"he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.","the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs",0.08,"and, to"
61880,"Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",COVID-19 is a potential zoonotic disease,0.08,"zoonotic, a"
61881,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.08,"the, also"
61882,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","Together with SARS-CoV, bat SARS-like CoV and others also  

fall into the genus beta-coronavirus",0.08,"the, into"
61883,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV",0.08,"the, is, sequence, that"
61884,"nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.08,"studies, the, to, and"
61885,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.08,"the, to, for, reservoir, is, on, and, palm"
61886,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.08,"a, of, the, and, it, with"
61887,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.08,"on, the, of, and, natural, a"
61888,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","bats are con- 

sidered the natural host reservoir of SARS-like coronavirus.1",0.08,"bats, are, natural, of"
61889,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.",0.08,"the, been, or, have"
61890,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Initially, an outbreak involving a local market, the  

Huanan Seafood Market, with at least 41 people was reported.1 

The local health authority issued an “epidemiologic alert” on  

December 31, 2019, and the market was shut down on January  

1, 2020. A total of 59 suspected cases with fever and dry cough  

were referred to a designated hospital (the Jin Yin-tan Hospital).  

Of the 59 suspected cases, 41 patients were confirmed by next- 

generation sequencing or real-time reverse transcription-poly- 

merase chain reaction (RT-PCR). Twenty-seven (66%, 27/41)  

patients had history of Huanan Seafood Market exposure",0.08,"the, a, was, to, at, and, with, health"
61891,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","However, the disease spread rap- 

idly and globally. Not only familial clusters but also outbreaks  

in ocean liners were reported",0.08,"in, but, the, and"
61892,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir",0.08,"revealed, that, sars-cov-2, the"
61893,"f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.08,"of, the, have, used"
61894,"Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.08,"the, viruses, reservoirs, of"
61895,"t the 

whole genome analysis level, our findings also indicate that bats are more likely the hosts for the COVID-19 

virus than pangolins.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.08,"the, findings, that, bats"
61896,"Considering macaques’ close phylogenetic rela- 

tionship to humans, the possibility of the transfer of SARS-CoV-2 

from bats to them as intermediate hosts for the spillover to humans 

seems plausible","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.08,"to, the, sars-cov-2, for"
61897,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.08,"the, that, host, was"
61898,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.08,"is, the, to, human"
61899,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.08,"the, human, animal, to"
61900,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.08,"the, of, to, human, more, than"
61901,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.08,"the, to, for, is"
61902,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.08,"the, to, and, sars-cov"
61903,"Since the spillover model postulates that an animal reservoir must be at  

the origin of the zoonosis","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.08,"the, be, at, of"
61904,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.08,"the, of, spike, could, and, to"
61905,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.08,"in, humans, to, spillover"
61906,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","All human infecting CoVs can cause mild to severe infection in 

humans and used spillover intermediate hosts",0.08,"to, and, used, in"
61907,". In fact, many 

such bat coronaviruses have genetic sequences similar to 

SARS-CoV and SARS-CoV-2.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.08,"bat, genetic, sars-cov, and"
61908,"Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.08,"viral, of, the, that"
61909,"SARS- 

CoV-2 virus most probably has its ecological reservoir in bats",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.08,"has, reservoir"
61910,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","several studies have shown that pan- 

golin may confer partial spike genes to SARS-CoV-2",0.08,"sars-cov-2, spike, have, to"
61911,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.08,"of, that, have, and"
61912,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.08,"the, which"
61913,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",The virus which causes COVID-19 most probably has its ecological reservoir in bats,0.08,"the, in, bats, covid-19"
61914,"CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",Many of these CoVs can infect several animal species as well,0.08,"covs, can"
61915,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",Many of these CoVs can infect several animal species as well,0.08,"as, animal"
61916,"t has been suggested that SARS-CoV-2 passaged 

in several animal species before entering humans","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.08,"that, animal"
61917,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.08,"the, from, a, animals"
61918,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.08,"it, to, from, is"
61919,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.08,"the, a, from, for"
61920,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.08,"to, the, for, is"
61921,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","When a virus passes from animals to humans for the first time it  

is called a spillover event.",0.08,"the, is, it, for"
61922,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.08,"the, bats, from, to"
61923,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.08,"in, the, from, of"
61924,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.08,"to, from, is, in"
61925,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.08,"of, the, also, to"
61926,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","ARS-CoV, the cause of the SARS outbreak in 2003, is also closely related to  

coronaviruses isolated from bats",0.08,"the, also, of, is"
61927,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.08,"in, all"
61928,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",hese close genetic relations suggest that they all have their ecological origin in bat populations,0.08,"they, that"
61929,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","ats in the Rhinolophus genus are found across Asia, Africa, the Middle East, and Europe",0.08,"the, and, found, in"
61930,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.08,"the, to, human, animal"
61931,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.08,"and, to, an, animal"
61932,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.08,"to, the, and, in, from, have, an, or"
61933,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.08,"sars-cov-2, animal, a, and"
61934,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.08,"is, that, and, all"
61935,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.08,"is, has, a, that"
61936,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,0.08,"natural, a, that, animal"
61937,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.08,"that, sars-cov-2, through, and"
61938,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.08,"an, animal, to, and"
61939,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.08,"and, that, to, of"
61940,"Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.08,"that, between, and, is"
61941,"As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.08,"to, of, be, contact"
61942,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.08,"to, by, and, sars-cov-2"
61943,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.08,"of, more, to, and"
61944,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.08,"of, to, that, sars-cov-2"
61945,"owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.08,"in, the, human, ace2"
61946,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.08,"virus, with, the, in"
61947,"its origins are “zoonotic,” and the virus was transmitted “natu- 

rally” from bats to humans, possibly from a food market in Wuhan, China",COVID-19 is a zoonotic virus,0.08,"virus, a"
61948,"Their analysis showed that the backbone of the new coronavirus’s genome most  

closely resembles that of a bat coronavirus discovered after the COVID-19 pan- 

demic began",COVID-19 is a zoonotic virus,0.08,"a, covid-19"
61949,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.08,"and, the, viruses, to"
61950,"A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (","Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs",0.08,"of, in, coronaviruses, four"
61951,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.08,"the, of, coronaviruses, beta"
61952,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.08,"to, as, belonging, the"
61953,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.08,"with, sars-, and, the"
61954,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.08,"of, and, the, bat"
61955,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.08,"and, of, the, human"
61956,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.",0.08,"to, the, sars, and, of, that, identity, approximately"
61957,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","external subdomain shows 40% identity in amino  

acid sequences in comparison with sequences of  

SARS-related coronaviruses.",0.08,"amino, acid, of, in"
61958,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","On the other hand, the comparative  

genome analysis by Andersen et al (21) revealed that  

SARS-CoV-2 originated through natural selection  

and not from a laboratory manipulation.",0.08,"and, from, natural, the"
61959,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.08,"is, between, and, that"
61960,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.08,"et, al., the, and"
61961,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.08,"and, bat, between, the"
61962,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","Tang et al. (23)  

revealed that the genomic variation between SARS- 

CoV-2 and bat SARSr-CoV (RaTG13) is only 4% and  

17% at neutral sites.",0.08,"and, is, that, bat"
61963,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type",0.08,"the, and, type, of"
61964,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Wild animal hosts and infected patients are currently the main sources of disease which is  

transmitted via respiratory droplets and direct contact.",0.08,"and, of, which, the"
61965,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.08,"that, market, in, was, were, a"
61966,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.08,"a, was, that, and"
61967,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV",0.08,"within, of, are, the"
61968,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.08,"and, from, in, the, of, sars-cov-2"
61969,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.08,"in, bat"
61970,"Of the three possibilities —  

natural, accidental, or deliberate  

— the most scientific evidence  

yet identified supports natural  

emergence.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.08,"of, the, most, identified"
61971,"the possible intermediate host animal was believed 

to be pangolin, of the Manidae family, commonly known as 

pangolins.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.08,"the, intermediate, of, family,"
61972,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.08,"in, the, of, a, on, these, were, that, likely, from"
61973,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.08,"the, genome, and, that"
61974,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans",0.08,"are, of, sars-cov-2, and"
61975,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.08,"of, the, bats, pangolins"
61976,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.08,"the, bats, most, to"
61977,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.08,"sars-, are, to, the"
61978,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.08,"are, to, may, the"
61979,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.08,"of, the, bats, may"
61980,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.08,"of, the, that, from, wild, for"
61981,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase",0.08,"from, for, the, of, that, sars-cov-2"
61982,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Bats are natural hosts of many of the known  

coronaviruses",0.08,"of, natural, the, many"
61983,"Bats may be the natural hosts of HCoV-229E, SARS- 

CoV, HCoV-NL63, and MERS-CoV","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.08,"bats, may, be, and"
61984,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.08,"coronavirus, from, bat, sars-cov-2"
61985,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats",0.08,"indicates, that, bats, and, in, between"
61986,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.08,"that, of, a, sars-cov-2, sequences, the"
61987,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.08,"the, of, that, a, receptor, and"
61988,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.08,"a, et, at, that, the, of"
61989,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis",0.08,"as, of, the, to, provided, evidence, study, that, suggested, intermediate"
61990,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","The  

pangolin is currently considered to be the most likely  

among the candidate intermediate hosts.",0.08,"the, among"
61991,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2",0.08,"the, has, identified, from"
61992,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.08,"and, been, the, of"
61993,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.08,"the, of, a, to, that, and, virus, it"
61994,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.",0.08,"the, to, a, virus, that, and, infect, of"
61995,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.08,"to, and"
61996,"Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.08,"related, to"
61997,"Malayan pangolins (Manis javanica)  

illegally imported into Guangdong province  

contain coronaviruses similar to SARS- 

CoV-22","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.08,"coronaviruses, to"
61998,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","he Malay pangolin  

GD/P1L and GD/P2S coronaviruses are closely related  

to SARS-CoV-2.",0.08,"and, to, coronaviruses, are"
61999,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.08,"a, the, be, of"
62000,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","results suggest that the pan- 

golin may be a long-term host of these pathogens.",0.08,"that, may"
62001,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.08,"in, chinese, the, an, and, of"
62002,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.08,"the, a, of, sars-cov-2"
62003,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.08,"that, virus., sars-cov-2, is"
62004,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.08,"a, the, of, is"
62005,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.",0.08,"the, is, that, of, retrospective, a"
62006,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.08,"is, the, covid-19, at"
62007,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019",0.08,"in, to, at, the"
62008,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.08,"in, a, of, to, yunnan, the, from, bat"
62009,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.08,"an, the, from, in"
62010,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus",0.08,"the, identified, bat, rhinolophus"
62011,"zoonotic corona- 

viruses have become an increasing threat to human health,","Since then, viruses closely related SARS-CoV-2  

have been described in Rhinolophus shameli bats caught in 2010 in  

Cambodia",0.08,"viruses, have"
62012,"Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)","ACE2 receptor highlighted a potential affinity between SARS-CoV-2  

spike and pangolin ACE2",0.08,"and, a"
62013,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.08,"and, of, within, the"
62014,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.08,"in, the, of, that, for, was, a, and"
62015,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.",0.08,"within, the, that, for"
62016,"SARS-CoV-2 contains 

neither the genetic fingerprints of any of the reverse genetics 

systems that have been used to engineer coronaviruses nor 

does it contain genetic sequences that would have been 

“forward engineered” from preexisting viruses, including the 

genetically closest sarbecoviruses","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.08,"of, have, been, coronaviruses"
62017,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","naturally occurring polybasic furin cleavage sites have  

been described in other lineages of coronaviruses such as MERS-CoV,  

HKU1, HCoV-OC43 or IBV",0.08,"in, have, been, or"
62018,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.08,"the, furin-cleavage, of, in"
62019,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","The natural occurrence of  

furin-cleavage sites in various viruses has been documented for long.",0.08,"the, has, been, of"
62020,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.08,"sars-cov-2, the, of, natural"
62021,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.08,"a, of, the, origin"
62022,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (",0.08,"of, in, the, ("
62023,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","We believe the coronavirus was originally transmitted to human by 

animals rather than by a laboratory leak",0.08,"to, than"
62024,hese close genetic relations suggest that they all have their ecological origin in bat populations,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.08,"all, in"
62025,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.08,"virus, human"
62026,"Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature","Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains",0.08,"coronavirus, in"
62027,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.08,"to, a, as, the, recent, of, and, species"
62028,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.08,"recent, the, studies, genomic"
62029,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.08,"are, of, the, a"
62030,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.08,"by, virus, the, of"
62031,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",". Bats are a large-capacity ‘reservoir’ of CoVs, virus 

sampling by the China Ecological Health Alliance alone found around 

400 new coronaviruses strains",0.08,"the, of, bats, a"
62032,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.08,"that, were, to, this"
62033,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.08,"to, bats, this, found"
62034,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.08,"of, the, viruses, reservoirs"
62035,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.08,"a, the, bats,, and"
62036,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.08,"natural, and, the, genome"
62037,"Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.08,"sars-cov-, and, genome, the"
62038,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.08,"of, from, a, with"
62039,"WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.08,"a, with, the, its"
62040,"Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.08,"from, a, it, host"
62041,"The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.08,"the, with, of, and"
62042,"Nevertheless, a large body 

of virologic, epidemiologic, veterinary, and ecologic data establishes that the new virus, SARS-CoV-2, evolved directly or 

indirectly from a β-coronavirus in the sarbecovirus (SARS-like virus) group that naturally infect bats and pangolins in Asia 

and Southeast Asia.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.08,"a, the, in, pangolins"
62043,"It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.08,"it, sars-cov-2, a, the"
62044,"g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.08,"we, that, the, between, sars-cov-2, and, bat, pangolin"
62045,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.08,"found, that, sars-cov-2, to, pangolin, and, the, of"
62046,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.08,"the, of, location, most"
62047,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.08,"contact, of, to, be"
62048,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.08,"the, a, to, of"
62049,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.08,"to, of, possible, bat"
62050,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.08,"of, similar, viruses, the"
62051,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic",0.08,"the, to, of, wuhan"
62052,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.08,"and, sars-cov-2, to, by"
62053,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.08,"the, sars-cov-, genome, and"
62054,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.08,"the, and, with, 2"
62055,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.08,"that, the, sequences, of, sars-cov-2, a"
62056,"bats are also important reservoir species for a great 

range of coronaviruses","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.08,"bats, species, a, of"
62057,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.08,"two, and, the, which"
62058,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.08,"of, that, virus, with"
62059,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.08,"with, of, bat, virus"
62060,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.08,"in, of, virus, has"
62061,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.08,"of, sars-cov-2, a, that"
62062,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2",0.08,"of, that, bat, a"
62063,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","the later discovered that BANAL- 

52 strain is 96.8% similar to SARS-CoV-2",0.08,"that, the, is, to"
62064,"s with other coronaviruses, SARS-CoV-2 emergence 

likely resulted from multiple zoonotic events","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.08,"with, from"
62065,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.08,"human, virus"
62066,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.08,"the, a, zoonotic, of"
62067,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","Despite the fact that animal host of SARS-CoV2 has not yet been 

identified, zoonotic origin is supported by a substantial body of 

research.",0.08,"has, a, the, of"
62068,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Molecular phylogenetic analysis of the RdRp sequence of SARS- 

CoV-2 generally shows that RaTG13, Pangolin-CoV and SARS-CoV-2 

is part of the same group",0.08,"is, of, the, and"
62069,"genomic studies report that SARS-CoV-2  

has nucleotide differences that could only have arisen  

through natural selection and such differences are evenly  

spread throughout the genome","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.08,"sars-cov-2, has, and, the"
62070,"The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.08,"the, to, from, also"
62071,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","bats are also important reservoir species for a great 

range of coronaviruses",0.08,"of, coronaviruses, a, are"
62072,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","bats are also important reservoir species for a great 

range of coronaviruses",0.08,"of, bats, a, species"
62073,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","bats are also important reservoir species for a great 

range of coronaviruses",0.08,"a, bats, of, are"
62074,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.08,"the, of, in, to, were, support"
62075,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","In an experimental study, 

ACE2 from 25 species of bats were reported to support SARS-CoV-2 

entry, and the infection rates of several bats were comparable to those 

of humans ACE2",0.08,"from, to, in, the"
62076,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.08,"the, 2, with, and"
62077,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.08,"the, nucleotide, and, from"
62078,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2",0.08,"with, two, and, the"
62079,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease",0.08,"be, sars-cov-2, in, with"
62080,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).",0.08,"the, to, in, a, of, as, bats,, with, is, emergence, was, that, by, animal, and, other"
62081,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.08,"that, can, to, exchange"
62082,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,",0.08,"naturally, coronavirus, that, can"
62083,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.08,"bats, the, is, and, in, to"
62084,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.08,"bats, to, the, most"
62085,"Two S proteins from the bat coronavirus, BANAL-20-52 and RaTG13, 

show 95% and 93.1% nucleotide sequence similarities with SARS-CoV- 

2","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.08,"from, the, and, nucleotide"
62086,"The partial furin cleavage site of BANAL-116 and BANAL-247 consists of three  

amino acids instead of the four amino acid insertion for SARS-CoV-2","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.08,"the, and, amino, acid"
62087,"RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.08,"in, similar, to, the"
62088,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.08,"to, the, viral, a"
62089,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.08,"human, ace2, the, in"
62090,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","owever, due to a single amino acid 

change in RaTG13 (T403R), the S protein can now use human ACE2 for 

viral invasion (",0.08,"to, a, in, human"
62091,"Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.08,"in, the, with, other"
62092,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D",0.08,"a, sars-cov-2, to, be"
62093,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.",0.08,"may, to, sars-cov-2, humans"
62094,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.08,"to, an, the, very"
62095,all three BANAL series viruses also use ACE2 as an entry receptor.,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",0.08,"as, an"
62096,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.08,"the, to, evidence, of"
62097,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.08,"the, of, a, to, and, was"
62098,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.08,"the, of, that, laboratory"
62099,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility",0.08,"of, to, a, was"
62100,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.08,"the, of, to, in, market, were"
62101,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.08,"sars-cov-2, and, at, to"
62102,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.08,"sars-cov-2, to, and, in"
62103,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.08,"and, to, at, the, in, animal"
62104,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.08,"to, the, and, sars-cov-2"
62105,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.08,"that, the, of, market, in, was"
62106,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.08,"was, that, the, host"
62107,"Several teams have recently confirmed the genetic similarity 

between SARS-CoV-2 and the beta betacoronavirus of the subgenus 

Sarbecovirus (Tang et al., 2020). The genome sequence of the new virus 

is 96.2% identical to that of the bat","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.08,"the, genetic, of, that"
62108,"Nature is clearly a cauldron for in- 

tense and dangerous coronavirus evolution","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.08,"nature, coronavirus"
62109,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.08,"with, bat, sars-cov-2, similarity"
62110,"Most human virus strains are zoonotic in origin, 

including all previous human coronavirus strains","Bat coronavirus like RaTG-13 & Banal series with  

>96% similarity to SARS-CoV-2 found in nature",0.08,"in, coronavirus"
62111,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.08,"a, the, of, and, it, with"
62112,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.08,"and, with, from, to, the, in, of, a"
62113,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.08,"the, that, in, of, to, and, with, a"
62114,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.08,"the, that, with, of, sars-cov-2, it"
62115,"COVID-19 is considered to have started at the Huanan  

Seafood Wholesale Market (HSWM) in Wuhan on December 8, 2019","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.08,"covid-19, is, at, the"
62116,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","It is highly unlikely that SARS-CoV-2 is a completely artificial creation. Even if the COVID-19  

pandemic is the result of a research-related incident involving a chimeric virus or gain of function  

experiment at the WIV, the vast majority of SARS-CoV-2’s genome comes from nature.",0.08,"a, sars-cov-2, it, the"
62117,"Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.08,"in, the, result, of"
62118,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.08,"the, of, a, in, to, or, progenitor, virus"
62119,"ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.08,"the, of, in, likely"
62120,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China",0.08,"in, of, one, the, bats, most, and, more"
62121,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.08,"coronaviruses, the, beta, of"
62122,"involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.","ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs",0.08,"which, of"
62123,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.08,"viruses, and"
62124,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.08,"bat, the, sars-cov-2, bats"
62125,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.08,"for, to, virus, in, and, the"
62126,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.08,"in, and, the, for"
62127,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.08,"the, viruses, are, in, different, by, of, and"
62128,"; the  

amino acid sequences within the seven conserved  

domains within the genomic open reading frame 1ab  

(ORF1ab) are 94.6% identical to that of the original  

SARS-CoV","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.08,"the, within, are, of"
62129,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.08,"the, of, viruses, similar"
62130,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.08,"to, a, of, the"
62131,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.08,"can, that, exchange, to"
62132,"‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.08,"that, the, same, bat"
62133,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.08,"of, the, viruses, to, in, genetic"
62134,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.08,"have, to, from, a"
62135,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.08,"with, of, a, from"
62136,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.08,"from, with, sars-cov-2, of"
62137,"enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.08,"the, and, with, sars-"
62138,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level",0.08,"the, sars-, by, in"
62139,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.08,"a, in, the, that, search, for"
62140,"the team assessed a zoonotic spillover from an intermediate host as “likely to  

very likely,”",all three BANAL series viruses also use ACE2 as an entry receptor.,0.08,"an, as"
62141,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.08,"to, with, than, the"
62142,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.08,"of, the, to, human"
62143,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","This suggests that the BANAL series may be able to directly infect  

humans.",0.08,"be, to, that, may"
62144,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","This suggests that the BANAL series may be able to directly infect  

humans.",0.08,"the, to, be, that"
62145,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.08,"that, in, viruses, to"
62146,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.08,"and, have, the, at"
62147,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.08,"at, two, and, to"
62148,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.08,"the, a, to, two"
62149,"the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.08,"the, two, and, which"
62150,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.08,"a, the, to, less, closely, related"
62151,"aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.08,"to, the, and, is"
62152,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.08,"the, at, is, a"
62153,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2",0.08,"in, a, were, to, human, and"
62154,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","After the BANAL group of viruses, the next most closely related virus to SARS-CoV-2, as  

measured by highest average genetic similarity, is the bat SARS-related strain RaTG-13.",0.08,"virus, the, to, bat"
62155,"the virus is similar to MERS-CoV and SARS-CoV that had its origin in animal  

reservoirs","t was first  

isolated in bats and designated as BtCoV4991 in July 2013",0.08,"and, in"
62156,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.",0.08,"the, is, in, to, known, covid-19"
62157,zoonotic origins of SARS-CoV-2 by natural evolution,"Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.08,"origins, of"
62158,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Regardless of the circumstances 



39 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

surrounding its discovery, RaTG-13 is approximately 96.1% similar across the entire viral genom",0.08,"is, of, the, covid-19"
62159,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.08,"are, to, the, may"
62160,"scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.08,"the, with, to, than"
62161,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.08,"is, the, in, over"
62162,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.08,"sars-cov-2, humans, in, and"
62163,"The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.08,"the, covid-19, and, is"
62164,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.08,"the, that, be, in"
62165,"The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed","If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans",0.08,"the, is, and, it"
62166,"The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.08,"the, and, were, with, these, by, of, a, available, that"
62167,"there is no 

indication that the Wuhan Institute of Virology had studied viruses 

similar to SARS-CoV-2 or artificially modified coronaviruses before the 

COVID-19 pandemic","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.08,"the, wuhan, of, to"
62168,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5",0.08,"virus, isolated, in, guangdong, at, with, the, of"
62169,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.08,"less, closely, related, to, a, the"
62170,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.08,"that, the, at, of, virus, and, less, to"
62171,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.08,"this, only, the, with, that, for"
62172,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.08,"the, study, of, suggested, that, as, intermediate, evidence, provided, to"
62173,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.08,"the, of, more, than, to, human"
62174,"Attempts to experimentally generate  

a furin cleavage site in BANAL-236 through 6 serial passages in humanized mice and human intestinal 

cells failed.274 These experiments were conducted in animal biosafety level 3 (ABSL-3) conditions.2","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.08,"to, a, in, and, human, were"
62175,"Variant A is the closest to that discovered in bats, that 

had 96.2% sequence similarity to the human virus [6], and was thus 

considered the original human virus genome.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.08,"a, the, to, that, in, had, sequence, and"
62176,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.08,"the, that, known, to, have, sars, in, across, of, or, and, not"
62177,"The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.08,"the, have, from, an, in, or, to, and"
62178,"Moreover, Rothan and  

Byrareddy (10) revealed that the novel COVID-19  

virus has approximately 80% and 50% identity to  

SARS and MERS of bat origin, respectively.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.08,"and, that, the, approximately, identity, to, sars, of"
62179,"Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.08,"the, of, to, that, bats, as, reservoir, for"
62180,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.08,"the, sequence, of, identity, to, and, in, bats"
62181,"However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.08,"the, of, identity, to, that, not, from, bats"
62182,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.08,"following, the, that, in, a, as, it, to"
62183,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.08,"the, that, virus, to, a, of, and, it"
62184,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.08,"the, of, or, to, a, progenitor, virus, in"
62185,"Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.08,"a, and, in, the, that, led, to, sars"
62186,"The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.08,"the, of, scientific, that, a, virus, in, for"
62187,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.08,"the, identified, to, from, bats, in, of, this"
62188,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.08,"the, to, in, from, of, a, bat, yunnan"
62189,"The most likely candidate viral reservoirs are one or more species of horseshoe bats (Rhinolophus  

bats) living in the extensive limestone cave systems of Southeast Asia and South China","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.08,"the, most, one, more, of, bats, in, and"
62190,"Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.08,"the, genome, to, bat, coronavirus, and, a, one"
62191,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.08,"the, of, a, which, to, in, and, were, virus, at"
62192,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.08,"the, that, virus, to, infect, a, of, and"
62193,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.08,"on, in, the, of, a, from, that, these, were, likely"
62194,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.08,"the, that, in, researchers, of, were, to, by, and, with, a, had"
62195,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.08,"the, in, a, zoonotic, as, to, of, and"
62196,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.08,"recent, the, of, to, a, and, species, as"
62197,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.08,"from, animal, a, are, and, in, china, south"
62198,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.08,"the, that, of, are, market, and, in, at"
62199,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.08,"of, at, the, in, a, that, such, animal"
62200,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.08,"to, on, the, and, reservoir, is, palm, for"
62201,"The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.08,"the, emergence, of, is, in, a, animal, to, and, was, that, with, bats,, other, as, by"
62202,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.08,"a, on, and, were, to, of, in, the"
62203,"several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.08,"animal, to, and, in, at, the"
62204,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.08,"to, from, a, of, in, the, and, with"
62205,"Our retrospective analysis of scientific data supports the  

hypothesis that SARS-CoV-2 is indeed a naturally occurring virus.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.08,"retrospective, of, the, that, is, a"
62206,"RaTG-13 is the most closely related virus to  

SARS-CoV-2 known to be in the WIV’s possession prior to the COVID-19 pandemic.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.08,"is, the, to, known, in, covid-19"
62207,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.08,"in, the, of, researchers, a, to, by, had, with, were, and, that"
62208,"World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.08,"health, for, and, to, the, of"
62209,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.08,"the, of, covid-19, in, a, to"
62210,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.08,"that, the, covid-19, in, and, to, market,, of"
62211,"osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.08,"that, the, of, sars-cov-2, and, this, more, likely"
62212,"Phylogenetic tree analysis shows that SARS-CoV-2 has the  

closest evolutionary relationship with Bat-SL-CoV-2 (RaTG13) at the scale of the complete virus genome, and less  

similarity to Pangolin-CoV","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.08,"that, sars-cov-2, the, with, at, of, and, to"
62213,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.08,"the, to, in, a, of, on, were, and"
62214,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.08,"is, the, covid-19, and"
62215,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.08,"the, a, in, led, to, that, sars, and"
62216,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.08,"is, of, and, the"
62217,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.08,"all, that, and, is"
62218,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.08,"that, in, the, market, at, and, of, are"
62219,"one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.08,"one, of, these, with"
62220,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.08,"of, the, and, with, in, many"
62221,"2 Human pandemic 

and seasonal influenza viruses arise from enzootic viruses of 

wild waterfowl and shore birds. From within this natural res- 

ervoir, the 1918 pandemic “founder” virus somehow host- 

switched into humans","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.08,"and, from, of, this, the, into"
62222,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.08,"at, this, the, sars-cov-2, that, for"
62223,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.08,"this, that, sars-cov-2, the, be, of"
62224,"t is highly identical (96.2%) at the whole-genome 

level to Bat-CoV RaTG13, which was previously detected in 

Rhinolophus affinis from Yunnan Province, over 1500 km from 

Wuhan","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.08,"is, the, to, over"
62225,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","expended to make the simple point 

that COVID-19 had a natural origin.",0.08,"the, a, to, that"
62226,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.08,"to, and, that, sars-cov-2"
62227,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.08,"in, from, found, that, to, were, related, and"
62228,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.08,"to, that, sars-cov-2, bats"
62229,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","coronaviruses that were phylogenetically related to 

SARS-CoV-2 were found in rhinolophus bats in South Asian 

countries including China, Japan, Cambodia, and Thailand[2,6–8] 

and in pangolins smuggled to China from South Asian 

countries.[9,",0.08,"in, that, sars-cov-2, from"
62230,"hypothesis that SARS-CoV-2 was the result of enzootic  

circulation before spillover into people","Also proceeding 

from the current evidence, we regard the lab leak hypothesis as 

extremely unlikely",0.08,"hypothesis, the"
62231,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.",0.08,"a, which, the, in"
62232,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.08,"in, has, and, was"
62233,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.08,"sars-cov-2, natural, a, or"
62234,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.08,"origin, a, animal, or"
62235,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer",0.08,"humans, or, and, in"
62236,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.08,"with, the, a, its"
62237,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.08,"bat, a, in, the"
62238,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.08,"sars-cov-2, a, natural, or"
62239,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.08,"a, on, is, of"
62240,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.08,"sars-cov-2, a, of, is"
62241,"Although the RaTG13 coronavirus 

isolated from bat has about 96% identity with SARS-CoV-2","It is improbable that SARS-CoV-2 emerged  

through laboratory manipulation of a  

related SARS-CoV-like coronavirus",0.08,"coronavirus, sars-cov-2"
62242,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.08,"the, have, used, of"
62243,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","f  

genetic manipulation had been performed,  

one of the several reverse-genetic systems  

available for betacoronaviruses would  

probably have been used",0.08,"the, of, for, been"
62244,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.08,"the, that, data, virus"
62245,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.08,"the, that, genetic, is"
62246,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20",0.08,"that, sars-, cov-2, the"
62247,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.08,"that, the, bats, to"
62248,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","Given the similarity of SARS- 

CoV-2 to bat SARS-CoV-like coronaviruses2 

,  

it is likely that bats serve as reservoir hosts  

for its progenitor.",0.08,"to, the, bats, as, for, reservoir, of, that"
62249,"Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.08,"the, which, that, a"
62250,"These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.08,"a, in, the, rhinolophus"
62251,"s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.08,"that, the, is, which"
62252,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Mutations, insertions and deletions can occur  

near the S1–S2 junction of coronaviruses22,  

which shows that the polybasic cleavage site  

can arise by a natural evolutionary process.",0.08,"a, the, which, that"
62253,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.08,"in, the, of, we, to, virus"
62254,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The finding of SARS-CoV- 

like coronaviruses from pangolins with  

nearly identical RBDs, however, provides  

a much stronger and more parsimonious  

explanation of how SARS-CoV-2 acquired  

these via recombination or mutation",0.08,"from, and, the, of, sars-cov-2, a"
62255,"Analyses of 103  

genomes of the novel virus revealed the possible  

existence of two types of COVID-19 coronavirus,  

namely, 70% L type and 30% S ancestral type","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.08,"of, the, type, and"
62256,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.08,"that, the, sars-cov-2, based"
62257,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.08,"the, of, is, related"
62258,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","In the 

case of MERS, dromedaries were the principal host.",0.08,"of, the, were, in"
62259,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.08,"and, is, to, in"
62260,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Initial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage but one that does not reach 

100%.7",0.08,"a, one, to, the, coronavirus, bat, and, genome"
62261,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.08,"a, that, the, this"
62262,"Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.08,"found, that, a, the"
62263,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.08,"the, to, spike, of, could, and"
62264,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.08,"that, the, of, and, receptor, a"
62265,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.08,"and, more, of, to"
62266,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.08,"to, the, bats, and, in, of, sequence, identity"
62267,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats",0.08,"in, the, sequence, of"
62268,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.08,"the, to, and, which"
62269,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals",0.08,"and, to, the, evidence"
62270,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",The COVID-19 most likely developed from bat origin coronaviruses,0.08,"origin, likely"
62271,"The two SARS 

viruses, as well as SADS-CoV, are descended from viruses en- 

zootic in rhinolophid (genus, Rhinolophus), or horseshoe bats","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.08,"the, as, from, or"
62272,"research indicated that a Horseshoe bat virus strain found in China’s 

Yunnan Province has a genome similarity of 96.2% with SARS-CoV-2","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.08,"that, a, bat, of"
62273,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.08,"a, of, the, that, covid-19, these"
62274,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.08,"a, origin, animal, or"
62275,"Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.08,"these, a, is, of"
62276,"t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.08,"is, that, a, or"
62277,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.08,"these, bat, that, the, origin, is"
62278,"Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV","Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections",0.08,"a, origin, for, the"
62279,"Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.08,"of, is, on, a"
62280,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Moreover, these viruses have a single intact open reading frame 

on gene 8, which is a further indicator of bat-origin CoVs.",0.08,"of, is, a, these"
62281,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.08,"of, the, viruses, that"
62282,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.08,"these, viruses, the, that"
62283,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.08,"the, market,, and, of, to, that, covid-19, in"
62284,"

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than","Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019",0.08,"the, that, bats, hosts"
62285,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.",0.08,"viruses, are"
62286,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.08,"can, be, are, to, and, in"
62287,"zoonotic corona- 

viruses have become an increasing threat to human health,","CoVs are zoonotic pathogens originating in animals and can be transmitted to humans through 

direct contact.",0.08,"zoonotic, to"
62288,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","All CoVs that caused epidemics (including COVID-19) are believed to be originated 

in bats.",0.08,"that, are, all, in"
62289,"Within the sarbecovirus lineage, en- 

compassing SARS and SARS-like viruses, many identified 

genetic sequences are very similar to SARS-CoV and SARS- 

CoV-2",Bats are hosts of many coronaviruses,0.08,"many, are"
62290,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.08,"to, is, in, the"
62291,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.",0.08,"the, by, that, in"
62292,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.",0.08,"of, for, to, that"
62293,The virus which causes COVID-19 most probably has its ecological reservoir in bats,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.08,"the, covid-19, in, bats"
62294,"SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.08,"viruses, that, to, and"
62295,"SARS-CoV-2 is a β coronavirus; sequence similari- 

ties between SARS-CoV-2 and β coronaviruses iso- 

lated from bat species can be as high as 89.0% (Zhu N  

et al., 2020) to 96.2% (Zhou P et al., 2020b), which  

indicates that SARS-CoV-2 may be derived from a  

predecessor coronavirus endemic in bats","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.08,"between, and, indicates, that, in, bats"
62296,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.08,"in, bats, are, that, of, and"
62297,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.08,"in, that, the, be"
62298,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.08,"the, covid-19, of, with"
62299,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","The two thirds of the first Covid-19 patients were 

associated with the Huanan Seafood Wholesale Market in 

Wuhan City, Hubei Province, China",0.08,"in, of, the, covid-19"
62300,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals",0.08,"that, to, even, in"
62301,"This hypothesis found its rationale in the in-silico  

analysis of sequence similarities which indicated that SARS-CoV-2 was  

closely related to RaTG13 but displayed specific RBD sites similar to the  

pangolin virus (","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.08,"in, the, of, ("
62302,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","These studies have revealed a great diversity of 

sarbecoviruses in bats of the genus Rhinolophus (Rhinolo- 

phidae, commonly known as horseshoe bats), especially in 

China (",0.08,"a, rhinolophus, in, the"
62303,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.08,"in, by, sars-, the"
62304,"several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.08,"in, china, by, three"
62305,"Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.08,"bats, the, of, may"
62306,"Including SARS-CoV-2, other coronaviruses cross the  

species barrier into humans, which lead to outbreaks of  

severe and fatal respiratory diseases","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.08,"other, to, of, and"
62307,"SARS-CoV-2 has a natural origin 

and was selected either in an animal host before zoonotic transfer, 

or in humans following zoonotic transfer","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.08,"and, in, or, humans"
62308,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.08,"and, with, other, to, be, in"
62309,"o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.08,"their, and, or, of"
62310,"bats are also important reservoir species for a great 

range of coronaviruses","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.08,"bats, are, a, of"
62311,"The SARS-CoV was  

frst identifed in bats, and spread to other animals in difer- 

ent geographic regions","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.08,"the, sars-cov, in, and, to, other"
62312,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.08,"the, of, a, was, and, to"
62313,"First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.08,"of, the, in, to, were, market"
62314,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.08,"in, a, of, to, the, which, and, at, were, virus"
62315,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.08,"and, have, the, in, markets, china"
62316,"One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.08,"of, to, a, which, was, in"
62317,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.08,"in, of, have, the, is, from"
62318,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.08,"on, the, virus, with"
62319,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.08,"of, from, with, sars-cov-2"
62320,"This association suggested that SARS had a zoonotic origin, that the virus was an animal virus that  

spilled over into humans rather than a pre-existing human virus that had evolved increase transmissibility  

or pathogenicity. Additional retrospective case identification, coupled with seroprevalence studies showed,  

“that early cases of SARS occurred independently in at least five different well-separated municipalities in  

Guangdong Province” further suggesting a zoonotic origin.540 Investigators also discovered at least four  

SARS patients with infections during isolated outbreaks in 2004 did not have contact with an existing SARS  

case, but all four had previous exposures to live animals.5","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.08,"the, virus, with, of, in, at, guangdong, isolated"
62321,"The genetic sequence of the COVID- 

19 showed more than 80% identity to SARS-CoV and 50% to the MERS- 

CoV [5,19], and both SARS-CoV and MERS-CoV originate in bats","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.08,"the, sequence, of, in"
62322,"hese pa- 

tients were epidemiologically linked to a seafood and wet animal 

wholesale market in Wuhan, Hubei Province, China","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.08,"were, and, in, china"
62323,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","several pangolins, seized in anti-smuggling op- 

erations in southern China between August 2017 and 

March 2019 and studied by three different Chinese teams 

(Lam et al. 2020; Liu et al. 2019; Xiao et al. 2020), were 

found positive for SARS-CoV-2-like viruses",0.08,"by, three, in, china"
62324,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","The Guangdong Wildlife Rescue Center received 21 

live Malayan pangolins from the Anti-smuggling Customs 

Bureau on 24 March 2019; most individuals, including 

adults and subadults, were in poor health, and their 

bodies were covered with skin eruptions. All these Ma- 

layan pangolins were rescued by the Guangdong Wildlife 

Rescue Center, however, 16 died after extensive rescue 

efforts. Most of the dead pangolins had a swollen lung 

which contained a frothy liquid, as well as the symptom of 

pulmonary fibrosis.” According to available data (Lam et 

al. 2020; Liu et al. 2019; Xiao et al. 2020), we estimate that 

43% of seized pangolins (26 positive individuals/60 

tested) were infected by at least one SARS-CoV-2-like virus",0.08,"available, by, a, of, the, that, were, and, these, with"
62325,"ats  

harbor the largest diversity of coronaviruses among mammals, including beta coronaviruses of which  

SARS-CoV-2 belongs","involves an anthropic origin, in which 

pangolins were contaminated because of their captivity.",0.08,"of, which"
62326,"RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.08,"the, in, from, an"
62327,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.08,"the, china, have, in, markets, and"
62328,"Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.","Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China",0.08,"the, wildlife, an, or"
62329,"B, we believe 

that SARS-CoV-2 is naturally part of the Sarbecovirus sub-gen","preliminary data provide some evidence that inter-animal 

transmission of SARS-CoV-2-like viruses occurred during 

their captivity.",0.08,"that, of"
62330,"Over the past 15 years, scientists have also identified global 

animal reservoirs of coronaviruses (in Africa, the Americas, the 

Middle East, Asia and Southeast Asia, and particularly China, the 

location of three of the four most recent emergences","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.08,"the, also, global, most"
62331,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.08,"the, is, which, to"
62332,"Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter","The concern related to CoVs 

infection dramatically rose after the COVID-19 global outbreak, for which a spill-over from wild 

animals is also most likely",0.08,"to, the, also, from"
62333,"Another batCoV sequence, RmYN02, was  

identified also in Yunnan in the horseshoe bat Rhinolophus malayanus","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.08,"identified, the, bat, rhinolophus"
62334,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum",0.08,"been, to, as, the"
62335,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario",0.08,"to, other, be, with, and, in"
62336,"A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2","zoonotic corona- 

viruses have become an increasing threat to human health,",0.08,"to, have"
62337,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.08,"the, for, of, to, and, health"
62338,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","World Health Organization for “scientific and collaborative field mis- 

sions” to “identify the zoonotic source of the virus",0.08,"of, the, to, virus"
62339,The COVID-19 most likely developed from bat origin coronaviruses,"However, we determined a natural origin of SARS- 

CoV-2 was more likely based on a comparative analysis of 

genomic data.",0.08,"likely, origin"
62340,"contaminated source from infected or sick  

wild animals in the wet market may have been the common  

origin.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.08,"or, the, have, been"
62341,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.08,"the, data, that, virus"
62342,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.08,"the, other, have, been"
62343,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus",0.08,"the, other, by, of, that, a"
62344,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.08,"in, animal, the, with"
62345,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","Most animal encounters by coronavirus virologists 

in the field are with bats, not other wildlife species.",0.08,"other, the, in, with"
62346,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.08,"that, sars-cov-2, an, to"
62347,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","Recent 

data show that SARS-CoV-2 did not come directly from a bat 

to a human; rather, it first evolved in an intermediate wildlife 

host",0.08,"a, host, it, from"
62348,"Xiao et al. (2020) furthermore suggest that SARS-CoV- 

2 may have been formed by a recombination of a pangolin CoV-like 

virus with one similar to RaTG13, and that pangolins are potentially 

the intermediate hosts for SARS-CoV-2","t is extremely unlikely that a non-bat interme- 

diate wildlife host transferred SARS-CoV-2 to a scientist 

directly or through a collected sample",0.08,"that, a, to, sars-cov-2"
62349,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.08,"the, humans, of, is"
62350,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.08,"that, the, of, laboratory"
62351,"Cross contamination between bats (or an intermediate 

host) and pangolins may have occurred during the trans- 

port from Southeast Asia, or during the storage in China, or 

in the wildlife markets in China","Compared with the 

millions of worldwide encounters of humans with wildlife 

that could transmit an infectious agent, the number of high- 

risk exposures of scientists doing field or laboratory work is 

miniscule.",0.08,"an, the, or, wildlife"
62352,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.08,"sars-cov-2, to, may, humans"
62353,"Even though the first patient 

was not reported to have attended this market, it would 

appear that this person has been in contact with people 

involved in the trade of living animals","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.08,"even, to, that, in"
62354,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans",0.08,"that, may, to, as"
62355,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","he ani- 

mal reservoir of SARS-CoV-2 has not yet been identified, but 

that doesn’t imply the possibility of a lab origin.",0.08,"but, of, the, has"
62356,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.08,"for, the, sars-cov, and"
62357,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.08,"the, been, other, have"
62358,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.",0.08,"the, and, have, for"
62359,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.08,"the, that, sars-cov-2, as, by, before"
62360,"he  

results revealed that 94% of SARS-CoV-2 nucleic  

acid-positive samples (31/33 cases) came from the  

western part of the Huanan Seafood Market, which  

includes facilities that provide wild animals for pur- 

chase","SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.",0.08,"that, of, sars-cov-2, from, the, for"
62361,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.08,"the, genome, bat, to"
62362,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The SARS-CoV-2 

genome was found to be 96.2% identical to the bat CoV RaTG13.4",0.08,"to, found, sars-cov-2, the"
62363,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario",0.08,"that, the, of, natural, origin, and"
62364,"When a virus passes from animals to humans for the first time it  

is called a spillover event.","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.08,"for, the, it, is"
62365,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.08,"sars-cov-2, of, the, it, that, with"
62366,"the  

genetic data irrefutably show that SARS- 

CoV-2 is not derived from any previously  

used virus backbone20","Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.",0.08,"the, genetic, that, is"
62367,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","the hypothesis of natural origin has a higher prior prob- 

ability given past human history as well as present viral abundance 

and diversity",0.08,"as, natural, and, the"
62368,"the evidence from the phylogenetic analysis indicates that the 

COVID-19 belongs to the genus betacoronavirus, which includes SARS- 

CoV, that infects humans, bats, and wild animals","no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere",0.08,"the, evidence, to, and"
62369,"A 

huge number of unknown viruses exist in their natural reservoirs 

and continue to evolve, which results in the generation of new 

strains.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.08,"a, in, which, the"
62370,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,",0.08,"in, the, an, bat"
62371,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.08,"and, to, that, sars-cov-2"
62372,"Coronaviruses (CoVs) are a large group of viruses common among many animals, including 

humans.","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.08,"are, viruses"
62373,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","SARS-CoV-2 was made from viruses that are nearly identical to 

RaTG13 and MP789.",0.08,"viruses, to, and, that"
62374,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.08,"bats, are, in, of"
62375,"The infectious sources of SARS-CoV-2 are in- 

fected animal hosts and other humans","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.08,"of, sars-cov-2, are, and"
62376,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).",0.08,"that, bats, are, of, and, in"
62377,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","one of these bat coronaviruses, 

BANAL-52, demonstrates even higher overall genome similarity with 

SARS-CoV-2 (96.8%) than RaTG13 (96.2%).",0.08,"of, with, these, one"
62378,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","provides the most 

conclusive evidence that known viruses from WIV cannot be viewed 

as SARS-CoV-2′s templates",0.08,"most, that, the, evidence"
62379,"several independent research groups have identified that SARS-CoV-2 belongs to β-coronavirus, with highly 

identical genome to bat coronavirus, pointing to bat as the natural host","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.08,"identified, that, to, the"
62380,"A research  

team from the South China Agricultural University  

(Guangzhou, China) has identified a coronavirus strain  

from pangolins, which has 99% sequence similarity  

with SARS-CoV-2","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.08,"from, the, has, identified"
62381,"Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1","hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.",0.08,"the, especially, is, to"
62382,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","the genetic similarity of SARS-CoV-2 with other 

coronaviruses appears to be completely consistent with the hypoth- 

esis of its natural origin.",0.08,"natural, of, the, to"
62383,"‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA","RBD of SARS-CoV-2 was also shown to bind ACE2 receptors 

of bats, which makes the scenario of its emergence in these animals 

plausible",0.08,"these, to, the, in"
62384,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.08,"is, a, coronavirus, the"
62385,"t is believed that the virus  

is zoonotic and bats may be the culprits because of sequence  

identity to the bat-CoV","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.08,"is, that, the, sequence"
62386,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.08,"that, has, a, is"
62387,"t can therefore be assumed that 

coronavirus nucleotide fragments can exchange naturally to produce 

this particular furin cleavage site,","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.08,"can, that, coronavirus, naturally"
62388,"Most of the early reported cases have been in that market, which was closed later by the Chinese 

authority.","the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature",0.08,"the, in, that, by"
62389,"explain why existing genetic data, viral diver- 

sity and past human history suggest that a natural origin of the virus is the most likely 

scenario","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.08,"and, that, natural, origin, of, the"
62390,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.08,"that, be, sars-cov-2, are, in, with"
62391,"Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.08,"the, to, be, in, of, than"
62392,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.08,"hosts, that, for, the"
62393,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.08,"recent, studies, the, genomic"
62394,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.08,"sars-cov-2, the, that, based"
62395,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.",0.08,"for, sars-cov-2, be, that"
62396,"The newly identified SARS-CoV-2 has been sus- 

pected to extend to humans from bats through  

pangolins even though conclusive evidence in  

support of this is yet to be found","The results obtained 

from various AI-enabled experiments using clustering algorithms demonstrate that all examined SARS-CoV-2 

genomes belong to a cluster that also contains bat and pangolin coronavirus genomes.",0.08,"the, sars-cov-2, to, from"
62397,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","provides evidence 

strongly supporting scientific hypotheses that bats and pangolins are probable hosts for SARS-CoV-2",0.08,"for, evidence, supporting, that"
62398,"She added, “I have yet to see an alternative explanation for the 

multiple threads of evidence supporting zoonosis. No infected 

animals at the market (because samples weren’t taken to look for 

said infected animals) doesn’t disprove all the other evidence that 

very clearly points to the market.","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.08,"to, the, of, at, market, that"
62399,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",0.08,"that, the, of, at, a, et"
62400,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.08,"genome, the, bat, sars-cov-2"
62401,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.08,"the, sars-cov-2, at, by"
62402,"COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.","Zhou et al. (2020) advocate a probable 

bat origin of SARS-CoV-2 by using complete genome sequences of five 

patients at the beginning of the outbreak in Wuhan, China",0.08,"a, in, the, sars-cov-2"
62403,"Notably, WHO  

Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence  

supporting a laboratory accident was insufficient and offered to provide additional resources  

to fully evaluate the possibility","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.08,"of, a, was, to"
62404,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","One of 

these sequences shows 96.2% similarity to a genome sequence of a 

coronavirus, denoted RaTG13, which was previously obtained from 

a Rhinolophus affinis bat found in Yunnan province of China.",0.08,"of, a, which, to, in, was"
62405,"sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.08,"of, and, related, sampled"
62406,"Clearly, the PRRA insertion in SARS-CoV-2 does not 

coincide with the canonical furin motif. Besides, the RRAR amino acid 

sequence at S1/S2 cleavage sites in feline coronaviruses (FCoV) can- 

not be cleaved by furin protease","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.08,"in, sars-cov-2, with, be"
62407,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.",0.08,"that, are, sars-cov-2, be, with, in"
62408,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.08,"other, the, of, and, in, this"
62409,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.08,"a, the, on, natural, of, and"
62410,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.",0.08,"a, of, the, by, that, other"
62411,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.08,"belonging, to, the, as"
62412,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.08,"the, been, as, to"
62413,"n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa","m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re",0.08,"sars-cov-2, have"
62414,"another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV","bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.",0.08,"sars-cov-2, cov"
62415,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin",0.08,"as, the, of, and, are, viruses, other, such"
62416,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.08,"evidence, to, the, that"
62417,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.08,"that, evidence, in, to"
62418,"A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.08,"the, genome, that, and"
62419,", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [","‘15’’). These are 2 viruses closest to SARS-CoV- 

2 based on the whole genome analysis. Results in Figs. 7C and 7D 

therefore provide evidence that bats or pangolins could be possible 

hosts for SA",0.08,"the, that, these, viruses"
62420,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.08,"the, that, for, within"
62421,"The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.08,"the, bats, sars-cov-2, bat"
62422,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.08,"for, the, that, only, this, with"
62423,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.08,"at, the, that, for, sars-cov-2, this"
62424,"Genomic analysis suggests that the COVID-19 virus originated in bats 

and transmitted to humans through unknown intermediate hosts in the Wuhan seafood market, 

China, in December of 2019","

Fig. 7E. At this stage, only bat CoV RaTG13 is within the same cluster 

with SARS-CoV-2 (cluster ‘‘17’’). We thus believe that bats are the more 

probable hosts for SARS-CoV-2 than",0.08,"that, the, bats, hosts"
62425,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","osada (2020) that 

investigates the polyprotein 1ab of SARS-CoV-2 and suggests that this 

novel coronavirus has more likely been arisen from viruses infecting 

bats rather th",0.08,"the, and, of, that, this, sars-cov-2, more, likely"
62426,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.08,"the, with, that, pangolin, and, bat"
62427,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",0.08,"that, the, is, bat, origin, these"
62428,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.08,"in, is, the, sars-cov-2"
62429,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘",0.08,"the, in, as, to, of, and"
62430,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","s again observed that the similarity between SARS-CoV-2 

and bat CoV RaTG13 (or Guangdong pangolin CoV) is larger than the 

similarity between bat SARS CoVs, which share the same bat",0.08,"is, the, which, that"
62431,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","‘‘3’’. We thus suggest that SARS-CoV-2 probably has the same origin 

with bat CoV RaTG13 or Guangdong pango",0.08,"that, the, bat, same"
62432,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","o 0.0001, the SARS-CoV-2 

sequences create their own cluster ‘‘22’’ and this questions the probable 

bat or pangolin origin of SA",0.08,"or, of, and, their"
62433,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","g. 10B, we also 

find that the similarity between SARS-CoV-2 and bat CoV RaTG13 (or 

Guangdong pangolin CoV) is larger than the similarity between viruses 

having the same",0.08,"we, between, sars-cov-2, and, the, pangolin, that, bat"
62434,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.08,"origin, the, sars-cov-2, and, are, into"
62435,"All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection","xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol",0.08,"all, have, they, and"
62436,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.08,"have, in, bats, that"
62437,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.08,"in, bats, that, sars-cov-2"
62438,"m. 

Once we have been able to identify SARS-CoV-2 as belonging to 

the Riboviria re","n CoV. 

This implies that SARS-CoV-2 may have originated in bats or pa",0.08,"have, sars-cov-2"
62439,"Indeed, the 

reservoirs for SARS-CoV and many other emerging patho- 

gens, notably EBOV, have not been identified.","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.08,"the, for, and, have"
62440,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.08,"the, in, genome, from"
62441,"According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.08,"virus, from, and, the"
62442,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.08,"the, of, virus, in"
62443,"The results of various clustering experi- 

ments show that SARS-CoV-2 genomes are more likely to form a cluster 

with the bat CoV RaTG13 genome than pangolin CoV genomes,","Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat origin 

of the virus based on similarities between these sequences and those 

obtained from bat CoVs previously reported in China",0.08,"the, of, bat, genome"
62444,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.08,"the, of, and, are, to, other"
62445,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.08,"that, the, of, to, a, other"
62446,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Other studies 

afterwards found that SARS-CoV-2 genome sequences are also similar 

to pangolin CoV sequences and accordingly raised a hypothesis on 

the pangolin origin of SARS-CoV-2.",0.08,"sars-cov-2, and, of, the, to, pangolin, found, that"
62447,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.08,"sars-cov-2, and, that, with"
62448,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","data showed that SARS-CoV-2 S-protein has  

highest similarity to Bat-SL-CoV-2 and Pangolin-CoV with 97.4% and  

89.7%, respectively",0.08,"has, and, to, that"
62449,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.08,"the, to, and, with"
62450,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.08,"the, and, of, sars-cov-2"
62451,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.08,"sars-cov-2, to, and, is"
62452,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","The E-protein of SARS-CoV-2 is 100% identical  

with Bat-SL-CoV-2, Pangolin-CoV, and Bat-SL-CoV, and is 94.7% iden­ 

tical to SARS-CoV",0.08,"the, is, of, to, and, with"
62453,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The identity of SARS-CoV-2 M-protein is the same  

with Bat-SL-CoV-2, Pangolin-CoV and Bat-SL-CoV with 98.6%, but  

89.1% with SARS-CoV.",0.08,"and, sars-cov-2, the, with"
62454,"As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.08,"of, the, with, sars-cov-2"
62455,"It was  

discovered in 2021 in Laos by a joint Laotian-French team along with two other closely related SARS- 

related coronaviruses, BANAL 103 and BANAL 236 which are both 90% similar to SARS-CoV-2 at the  

whole genome level","The N-protein of SARS-CoV-2 showed highest  

identity with Bat-SL-CoV-2 (99%) followed by Pangolin-CoV (97%), Bat-  

SL-CoV (94.2%), SARS-CoV (90%)",0.08,"by, with, sars-cov-2, the"
62456,"Such studies argued that  

SARS-CoV-2 is very likely to be originated from Bat-SL-CoV-2 (RaTG13).","Further recombination analysis revealed the pathway for spillover transmission from Bat-SL-CoV-2  

and Pangolin-CoV.",0.08,"from, bat-sl-cov-2"
62457,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.08,"that, sars-cov-2, and, in"
62458,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.08,"for, the, of, and"
62459,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","we provide evidence for recombination event between Bat-SL-CoV-2 and Pangolin-CoV  

that resulted in the emergence of SARS-CoV-2",0.08,"the, that, in, for, of, and"
62460,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","In the both scenarios, the  

CoV originated from bats, and amplified in a mammalian host, e.g. Hi­ 

malayan palm civet (SARS) and dromedary camels",0.08,"a, the, in, from"
62461,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Bat-SL-CoV-2 is the major parent with 98.4% simi­ 

larity and Pangolin-CoV is the minor parent with 88.2% similarity for  

recombinant SARS-CoV-2",0.08,"the, and, with, for"
62462,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.08,"the, of, and, virus"
62463,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","The phylogenetic tree shows that SARS-CoV-2 has the closest  

evolutionary relationship with Bat-SL-CoV-2 at the scale of the complete  

virus genome, and less similarity to Pangolin-CoV",0.08,"and, phylogenetic, that, of"
62464,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","However, the RBD of  

Bat-SL-CoV-2 showed low aa identity (78%) to SARS-CoV-2, suggesting  

that SARS-CoV-2 possibly was not transmitted directly from bats to  

humans.",0.08,"to, the, bats, not, of, from, that, identity"
62465,"Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD","In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.",0.08,"of, pangolin-cov, at, rbd"
62466,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.08,"the, of, we, virus, that, but"
62467,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.08,"the, of, that, virus, this, to"
62468,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.08,"the, be, that, of, sars-cov-2, this"
62469,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.",0.08,"to, this, the, of, that, sars-cov-2"
62470,"In contrast, the RBD of Pangolin-CoV is almost identical to  

SARS-CoV-2 (98%) at the aa level, proposing that mutations in Pangolin  

gave new features to CoV which enable the virus to bind to hACE2.","Together Bootscanning curves and comparison of phylogenetic  

tree topology of major and minor parental viruses revealed recombi­ 

nation event between Bat-SL-CoV-2 and Pangolin-CoV with position of  

breakpoint pairs at RBD",0.08,"rbd, of, pangolin-cov, at"
62471,"The ability of SARS-CoV-2 to cross the barrier of murine species may be 

obtained through simple mutations. It is also possible for SARS-CoV-2 

to acquire the ability to infect humans and spread between humans by 

some simple mutation.","Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.",0.08,"the, of, to, by"
62472,Many of these CoVs can infect several animal species as well,"The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.08,"animal, as"
62473,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","The first bias was observed in those articles that  

identify bat as animal origin for SARS-CoV-2.",0.08,"that, for, the, in"
62474,hese close genetic relations suggest that they all have their ecological origin in bat populations,"Hence, they predicted that Bat-SL-CoV is the most probable  

source of SARS-CoV-2",0.08,"that, they"
62475,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.08,"sars-cov-2, a, virus, an, and, the"
62476,"bat CoV RaTG13 is shown 

closer to SARS-CoV-2 than pangolin CoVs.","another study suggesting SARS-CoV-2 might be a recombinant  

virus between the Bat-SL-CoV and an origin-unknown CoV",0.08,"cov, sars-cov-2"
62477,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","The preponderance of 

scientific evidence at this time indicates that SARS-CoV-2 is representative of a type of corona- 

virus that has been circulating in feral animal populations for decades",0.08,"the, of, a, in, that, virus, for, scientific"
62478,"Genomic analysis revealed that SARS-CoV-2 is phylogenet- 

ically related to severe acute respiratory syndrome-like (SARS-like) bat viruses, therefore bats could be 

the possible primary reservoir","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.08,"that, sars-cov-2, be, the"
62479,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","COVID-19 would still be a zoonosis in the sense 

that SARS-CoV-2 originated from a feral animal but the trigger from the pandemic 

would be human activity in a research laboratory or possibly during the search in caves 

for bats.",0.08,"the, search, for, in, a, that"
62480,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.08,"the, of, and, what"
62481,"If SAR-CoV-2 spilled over in humans through zoonosis, it is unlikely that the primary COVID-19 case will  

ever be identified and it is unlikely that the world will ever know exactly when SARS-CoV-2 first infected  

humans","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.08,"it, is, the, and"
62482,"f SARS-CoV-2. This is because we observe considerable similarity be- 

tween SARS-CoV-2 and bat CoV RaTG13 (or Guangdong pangolin CoV) 

compared to the similarity between viruses that originated in","The natural reservoir is enormous, and it is not even clear what 

would define an exhaustive search with regard to sampling sites and number of sam- 

ples analyzed",0.08,"is, and, to, the"
62483,"Of these, four are endemic  

human coronaviruses HCoV-229E (alpha), HCoV- 

NL63 (alpha), HCoV-OC43, and HCoV-HKU1 (beta),  

which are responsible for mild common cold  

symptoms mostly in lung infections and are mostly  

associated with bats, rodents, cows and pigs","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.08,"of, four, coronaviruses, in"
62484,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","A recent study of 411 bat samples from a small geographic region in China identified 

24 coronaviruses including four close relatives of SARS-CoV-2 (",0.08,"in, a, of, sars-cov-2"
62485,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.08,"the, for, a, and"
62486,"Another piece of evidence that supports the COVID-19 is of bat origin is 

the existence of a high degree of homology of the ACE2 receptor from a 

diversity of animal species, thus implicating these animal species as 

possible intermediate hosts or animal models for COVID-19 infections","Also supporting a zoonotic origin are historical precedents for prior pandemics, 

including the 1918 and 2009 flu pandemics, SARS-CoV-1, MERS-CoV, and HIV",0.08,"the, origin, a, for"
62487,"Human-to-human transmission of SARS-CoV-2 occurs 

mainly between family members, including relatives and 

friends who intimately contacted with patients or incuba- 

tion carriers","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.08,"of, sars-cov-2, with, patients"
62488,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.08,"for, of, sars-cov-2, zoonotic"
62489,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.08,"a, be, to, sars-cov-2"
62490,"Evolutionary analysis of COVID-19 virus revealed that it is most similar to the bat SARS-like 

coronaviruses, and for the similarity, it was named SARS-CoV-2.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.08,"of, that, to, for"
62491,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common",0.08,"that, be, for, sars-cov-2"
62492,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.08,"that, a, cause, of, and, to"
62493,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","At present, RaTG13, which 

was found in Rhinolophus affinis in Yunnan Province, has the closest 

relationship with SARS-CoV-2, with 96.2% identity at the whole- 

genome level",0.08,"genome, the, in, with"
62494,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","RmYN02 detected in R. malayanus in 

Yunnan was 97.2%, similar to that of SARS-CoV-2 in the non- 

structural protein gene ORF1ab.",0.08,"the, in, similar, to"
62495,all available evidence suggests that SARS-CoV-2 has a natural animal origin and is not a manipulated or constructed virus.,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.08,"that, a, natural, animal"
62496,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses",0.08,"that, in, the, such, a, at, of, animal"
62497,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2",0.08,"the, in, to, very, of, and"
62498,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.08,"in, the, of, to, be, sars-cov-2,"
62499,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Although RaTG13 is the bat coronavirus known to be the closest 

to SARS-CoV-2, its amino acid sequence consistency in the RBD of S 

gene is less than 90%",0.08,"than, the, to, be, in, of"
62500,"genetic sequencing has been used to show that  

COVID-19 exists in bats,","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.08,"has, to, that, in"
62501,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.08,"that, bat, and, to"
62502,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries",0.08,"in, of, that, to, and, related"
62503,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","some research 

groups successively found highly homologous SARS-CoV-2 from 

smuggled Malayan pangolins (Manis javanica), including coron- 

avirus PRJNA57329813 and multiple lineages of coronaviruses (ho- 

mology as high as 85.5–92.4%).1",0.08,"and, of, groups, coronaviruses"
62504,"the pangolin hypothesis  

was repeated so many times in scientific papers and on social networks  

that was taken for a truth even within part of the scientific community.","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.08,"the, pangolin, that, of"
62505,"Recent studies suggest that wild species, such as white- 

tailed deer, may continue to harbor SARS-CoV-2 variants 

even after they no longer circulate in humans","One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.",0.08,"that, as, may, to"
62506,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.08,"the, related, of, is"
62507,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","Unlike RaTG13, the S1 protein, especially the five key amino 

acid residues of Pangolin-CoV, is more closely related to SARS- 

CoV-2 than to RaTG13,1",0.08,"is, especially, to, the"
62508,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.08,"sars-cov-2, to, high, genetic, and, in"
62509,"Bats are natural hosts of many of the known  

coronaviruses","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.08,"natural, of, many, the"
62510,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.08,"the, of, in, viruses, to, genetic"
62511,"The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.","SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.",0.08,"the, many, of, with, and, in"
62512,"The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.079754601,"the, of, is, in, a, been, to, and, sars-cov-2, it, that, with, human"
62513,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","The emergence of furin cleavage sites is common in the process 

of natural evolution. A total of 86 different furin cleavage sites have 

been identified in 249 coronavirus species worldwide, distributed in 

24 animal species in 28 countries since 1954 (Liu et al., 2021). Four 

of the seven coronaviruses known to infect humans carry furin cleav- 

age sites. These include HCoV-OC43, HCoV-HKU1, MERS-CoV and 

SARS-CoV-2 (Liu et al., 2021). It was discovered in the United States in 

1967 that Furin cleavage site (KNRRSRR↓AI) appears in HCoV-OC43 

(beta-CoV) (Lau et al., 2011; McIntosh, Becker, & Chanock, 1967; Su 

et al., 2016), and furin cleavage site (SSRRKRR↓SI) of HCoV-HKU1 was 

first discovered in China in 2004 (Woo et al., 2005). MERS-CoV with 

a furin cleavage site (LTPRSVR↓SV) first identified in Saudi Arabia in 

2012, originated in bats, can infect humans and camels (Coutard et al., 

2020; Memish et al., 2013; Wong, Li, Lau, & Woo, 2019). In addition, a 

furin site (TKRRSRR↓AI) was also detected in human intestinal coro- 

naviruses (HECV-4408, beta-CoV) first in Germany in 1988 (Zhang, 

Herbst, Kousoulas, & Storz, 1994). Furthermore, other viruses, such as 

the H5 and H7 influenza viruses, have also been reported possessing a 

new multi-base cleavage site that naturally arises by insertion (Decha 

et al., 2008; Garushyants, Rogozin, & Koonin, 2021; Taubenberger et al., 

2005; Tyshkovskiy & Panchin, 2021).",0.079754601,"in, the, of, it, is, to, that, sars-cov-2, been, with, human, and, a"
62514,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.079710145,"the, to, a, for, of, as, one, is, that, by, animal"
62515,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.",0.079710145,"that, to, one, as, the, animal, by, a, of, is, for"
62516,"Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”","he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering",0.079646018,"that, the, of, in, to, or, not, have, a"
62517,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage",0.079646018,"the, of, a, to, bat, viruses, that, from, this"
62518,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.079646018,"the, and, a, in, of, from, indicated, an, those"
62519,"he SARS-CoV-2 

ORIGIN OF COVID-19 957



receptor-binding domain, which has affinity for cells of various 

mammals, binds to human ACE2 receptors via a novel 

mechanism. 

Engineering such a virus would have required 1) published 

or otherwise available scientific knowledge that did not exist 

until after COVID-19 recognition; 2) a failure to follow obvious 

engineering pathways, resulting in an imperfectly constructed 

virus; and 3) an ability to genetically engineer a new virus 

without leaving fingerprints of the engineering","Rasmussen wrote that the role of the market in the pandemic’s 

emergence was covered up in ways that didn’t apply to SARS1 or 

Middle East respiratory syndrome (MERS). “The market was closed. 

Live animals were removed. Clearly evidence was suppressed, not 

collected, or not made accessible,” she said, “That doesn’t mean 

the evidence we do have doesn’t support a market origin. Existing 

affirmative evidence isn’t invalidated by a lack of other types of 

evidence.”",0.079646018,"of, to, a, have, or, that, not, in, the"
62520,"In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals","equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection",0.079646018,"the, of, found, for, as, at, was, to, and"
62521,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.079646018,"been, found, in, the, and, to, that, may, have"
62522,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.079646018,"and, the, have, been, to, in, found, that, may"
62523,"In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.","the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak",0.079646018,"in, the, of, taken, samples, that, from, this, outbreak"
62524,"equence-based 

analysis suggested bats as the key reservoir. DNA recombination 

was found to be involved at spike glycoprotein which assorted 

SARS-CoV (CoVZXC21 or CoVZC45) with the RBD of another Beta 

CoV, thus could be the reason for cross-species transmission and 

rapid infection","In May 2003, less than six months after the first known SARS cases, public health investigators  

sampling animals in live animal markets in the city of Shenzhen, located approximately 75 miles from  

Guangzhou, found that three of six sampled palm civets tested positive for SARS as did the only raccoon  

dog tested.545 Two Chinese Ferret Badgers at the market also tested positive for SARS antibodies. The virus  

collected from the animals was 99.8% similar to SARS.546 “These data indicated that at least three different  

wildlife animal species in the Shenzhen market were infected by a coronavirus that is closely related to  

SARS” and was the “first direct evidence that [SARS] existed in animals",0.079646018,"as, the, was, found, to, at, of, for, and"
62525,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.079646018,"in, the, those, from, an, and, a, indicated, of"
62526,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5",0.079646018,"to, that, the, of, bats, and, have, as, for"
62527,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.079646018,"viruses, to, the, coronavirus, in, bats, of, and, a"
62528,"Line- 

age A viruses are at least two mutations closer 

to bat coronaviruses, indicating that the an- 

cestor of SARS-CoV-2 arose from this lineage","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.079646018,"a, viruses, to, bat, that, the, of, from, this"
62529,"the identification of genetic sequences of raccoon dogs in samples taken from the  

market in early 2020 confirm that this susceptible intermediate host was at the market at the time of the  

outbreak","In 2017, the same group of researchers would publish the results of a five year (April 11 to October  

2015) longitudinal study on the same bat cave as the 2011-2012 study. By October 2015, researchers had  

taken 602 bat samples with 84 samples testing positive. 566 In total the study found 15 novel bat  

coronaviruses in a single cave. By comparing sections of these viruses to SARS, the researchers concluded,  

“all of the building block” SARS’s genome could be found in the 15 SARS-related coronaviruses found in  

the cave. Moreover, the viruses were sufficiently similar and present in sufficient density that recombination  

events were a likely occurrence, thus increasing the probability that SARS emerged from this specific cave  

in Yunnan Province. It took researchers approximately 14 years from the first outbreak of SARS to locate  

its viral reservoir in a Yunnan Province cave home to multiple species of horseshoe bats.",0.079646018,"the, of, in, samples, taken, from, that, this, outbreak"
62530,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.079646018,"in, a, of, to, the, bats, coronavirus, and, viruses"
62531,"Prior to the 2002-2003 SARS pandemic, bats were recognized as viral reservoirs for several  

zoonotic viruses. They were known to be susceptible to infections and to respond asymptomatically to many  

viral infections. Bats were not known to be a viral reservoir for coronaviruses. In the wake of the SARS  

pandemic, a 2004 study sampled 408 bats across nine species from Guangdong, Guangxi, Hubei, and  

Tianjin Provinces. A high percentage of the three species of horseshoe bats (Rhinolophus bats) sampled  

had SARS antibodies. “Genome sequence analysis indicated that SARS-related coronaviruses (SL-CoVs)  

present in bats have an almost identical genome organization to those of [SARS] isolated from humans or  

civets, sharing an overall sequence identity of 92%.”556 A further study found that approximately 84% of  

horseshoe bats sampled contained SARS antibodies.5","DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.",0.079646018,"to, the, bats, as, for, and, of, that, have"
62532,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China",0.079545455,"the, of, in, bats, also, southern, china"
62533,"The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”","SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission",0.079545455,"the, to, coronavirus, is, of, and, sars-cov-2"
62534,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The  

whole genome of SARS-CoV-2 shares 80% identity with  

that of SARS-CoV and is 96% identical to the bat coro- 

navirus BatCoV-RaTG13",0.079545455,"the, to, of, with, is, that, and"
62535,"Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “","SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.",0.079545455,"that, is, evidence, a, an, animal, to"
62536,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”",0.079545455,"and, be, for, to, other, the, in"
62537,"SARS-CoV-2 is believed to be a spillover of an 

animal coronavirus and later adapted the ability of human-to-human transmission","The viruses that WIV was known to have are more 

closely related to SARS-CoV-1,” adding that the most closely related 

SARS related coronavirus in WIV’s collection is different by more 

than 1100 mutations across its entire genome. 

“No amount of insertions, mutagenesis, or passaging in cells, 

transgenic mice, bats, or whatever else, can make it SARS-CoV-2,” 

she said, “I’m closely related to my sibling and my parents. If I got 

cancer or HIV (which would cause 

mutations/insertions/recombination of my genome), it would not 

turn me into my brother or my parents. Similarly, the WIV’s 

SARSr-CoVs can’t turn into SARS-CoV-2 at any containment level.”",0.079545455,"sars-cov-2, is, to, of, coronavirus, and, the"
62538,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.079545455,"the, to, as, a, that, in, events"
62539,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.079545455,"are, of, a, to, that, in, as"
62540,"SARS-CoV-2’s famous “spike 

protein”—specifically, its angiotensin converting enzyme 2 (ACE2) 

receptor that helps it bind to human cells—features one such 

sequence. This initially worried experts such as Jeremy Farrar, now 

chief scientist at WHO, when he first saw it. At the time, he thought 

that if someone had set out to adapt an animal coronavirus to 

humans by inserting a specific bit of genetic material, this is what 

it might look like. He has since been convinced otherwise by the 

weight of evidence for a natural origin.","Gostin says that there is considerable evidence that covid-19 

originated in Wuhan from a naturally occurring spillover from an 

animal to humans. “",0.079545455,"that, to, an, animal, a, is, evidence"
62541,"Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.079545455,"that, the, sars-cov-2, to, of, and, subsequent"
62542,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts",0.079545455,"that, palm, civets, from, the, market, at"
62543,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV",0.079545455,"which, the, by, to, and, sars-cov, also"
62544,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","virus that is regularly  

transmitted from an animal to a human is called a zoonotic virus",0.079545455,"from, to, a, virus, that, human, an"
62545,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.079545455,"is, that, of, to, by, and, an"
62546,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.",0.079545455,"and, the, of, bat, with, other, virus"
62547,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.079545455,"the, in, of, by, and, with, covid-19"
62548,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.",0.079545455,"from, a, virus, that, this, bat, in"
62549,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.079545455,"the, for, of, were, and, with, a"
62550,"As Kristian Andersen, professor in the department of immunology 

and microbiology at the Scripps Research Institute in California, 

puts it: “Scientists are lazy. If we want to make viruses in the lab, 

we follow recipes we’ve used for decades, because we know they 

work.” In other words, there would be some more recognisable sign 

in the genetic code of Sars-CoV-2, and the wildtype virus had no 

such laboratory “signature.”","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.079545455,"in, the, and, to, for, other, be"
62551,"In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus","Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS",0.079545455,"of, the, bats, for, and, sars, viruses"
62552,"The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.079545455,"the, in, of, by, and, shared, a"
62553,", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.079545455,"the, that, in, a, as, to, events"
62554,"Alignment of the full-length genome sequence of the  

COVID-19 virus and other available genomes of Betacoronavirus showed the closest  

relationship was with the bat SARS-like coronavirus strain BatCov RaTG13, identity 96%.","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.079545455,"of, the, virus, and, other, with, bat"
62555,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.",0.079545455,"is, to, in, the, with, bat, which"
62556,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","The RBDs of BANAL-52 and BANAL- 

103 are 97.4% similar to the RBD of SARS-CoV-2. The RBD of BANAL-236 is 96.9% like that of SARS- 

CoV-2",0.079545455,"the, are, to, of, is, that, and"
62557,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.079545455,"natural, of, a, related, to, that, in"
62558,"From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.","This suggests that the BANAL series may be able to directly infect  

humans.",0.079545455,"the, able, to, that, this, directly, infect"
62559,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.079545455,"the, a, in, to, suggesting, that, of"
62560,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.079545455,"and, into, with, species, to, or, a"
62561,"The same rhinolophid 

bats are also implicated in the emergence of SADS-CoV in 

southern China","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.079545455,"the, bats, also, in, of, southern, china"
62562,"Bats serve as the endemic animal reservoirs for the progenitor viruses of SARS  

and MERS","In 2013, a team of WIV researchers conducting a one year (April 2011 to September 2012)  

longitudinal survey of SARS-related coronaviruses in a single habitat in Kunming, Yunnan Province, made  

a breakthrough discovery. The researchers collected 117 samples from individual bats of which 27 tested  

positive for the presence of a coronavirus. 

562 Among the positive samples, researchers identified a total of  

seven different coronavirus strains circulating in this single bat colony. Most importantly, the researchers  

discovered two novel SARS-related coronaviruses, RsSHC014 and Rs3367, had a 95% similarity to SARS  

at the whole genome level.563 The two viruses were more closely related to SARS than any other previously  

discovered virus",0.079545455,"bats, the, for, viruses, of, sars, and"
62563,"SARS-CoV-2 may originate from a virus  

that is endemic in this bat species.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.079545455,"from, a, virus, that, in, this, bat"
62564,"This suggests that the BANAL series may be able to directly infect  

humans.","From the samples, the WIV team was also able for the first time to isolate a live SARS-related virus  

that was 99% similar to Rs3367. Experiments with this live virus sample, named bat SL-CoV-WIV1  

(WIV1), determined that like SARS, WIV1 used ACE2 as a cellular entry receptor and could directly infect  

human cells.564 Researchers would also create a chimeric virus by grafting the RsSHC014 to a mouse- 

adapted SARS “backbone.” This chimeric virus also used ACE2 as a cellular entry receptor and could  

directly infect human cells. In July 2013, the WIV team of researchers successfully isolated a second bat  

coronavirus from a sample taken from the Yunnan bat colony named bat SL-CoV WIV16 (WIV16).565 

WIV16 supplanted WIV1 as the closest known virus to SARS at the time of its discovery. WIV16 could  

also use ACE2 as an entry receptor, including for human cells.",0.079545455,"this, that, the, able, to, directly, infect"
62565,"Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely","At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat",0.079545455,"zoonotic, from, an, animal, as, the, for"
62566,"the samples isolated from the civets at the food 

market showed positive results for viral RNA detection, suggesting 

that the civet palm might be secondary hosts","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.079545455,"the, from, civets, at, market, that, palm"
62567,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.079545455,"from, in, at, with, the, of, on"
62568,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.079545455,"is, and, that, of, to, an, by"
62569,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.079545455,"and, by, with, the, covid-19, in, of"
62570,"With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.079545455,"with, the, of, were, a, for, and"
62571,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","The Huanan Market is the only Wuhan area market that PRC officials have released significant  

information about. In presentations for the WHO-China Joint Report, PRC researchers stated, “66% of the  

41 cases identified before 2 January 2020 were once exposed to the Huanan Market.” 642 Similarly,  

retrospective case identification by Chinese epidemiologists and public health experts shared with the WHO  

showed that a preponderance, but not all of early known COVID-19 cases had an association with the  

Huanan Market",0.079545455,"of, and, shared, by, a, in, the"
62572,"The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China","Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.",0.079545455,"the, covid-19, is, to, be, in, market"
62573,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.",0.079545455,"a, of, in, that, sars, the, to"
62574,"Among early cases associated with the Huanan Market, “vendors and [wholesale] purchasers  

accounted for 77% of all cases,” suggesting a significant occupation exposure risk associated with working  

or prolonged exposure to the market.645 However, PRC officials informed the WHO-China team that there  

were no COVID-19 infections in vendors involved in selling domesticated animals.646 This is a major  

difference between SARS-CoV-2 and SARS where live animal traders, particularly those handling palm  

civets, were much more likely to be infected than aquatic seafood, vegetable, and other vendors.647 By  

contrast, at the Huanan Market the majority of COVID-19 cases in vendors were among those selling  

seafood, livestock meat, poultry meat, and vegetables.","The COVID-19 is suspected to be emerged in the seafood market in Wuhan, China",0.079545455,"the, to, covid-19, in, is, be, market"
62575,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.079545455,"the, also, and, to, which, by, sars-cov"
62576,"In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.","Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)",0.079545455,"in, et, al., of, and, which, to"
62577,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.079545455,"and, species, into, a, or, with, to"
62578,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.079545455,"with, from, at, the, in, of, on"
62579,"At some  

point, an infected bat had to encounter a palm civet. However, as discussed, palm civets sampled from  

animal farms in multiple Chinese provinces tested negative for the virus or antibodies. By contrast, palm  

civets collected from multiple wet markets across southern China tested positive. Similarly, the earliest  

identified SARS cases, while all having recent exposure to live animals, were otherwise unrelated to one  

another, suggesting multiple independent zoonotic introductions of the virus across several live animal  

markets. In addition to palm civets and other small mammals, wet markets in Southern China also sell live  

bats, including various species of horseshoe bat","Zoonotic transmission from an unknown 

animal reservoir, as was the case for previous CoV outbreaks, appears 

far more likely",0.079545455,"an, as, from, animal, for, the, zoonotic"
62580,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","Holmes et al. reported that “both CGG codons are 

more than 99.8% conserved among the > 1,800,000 near complete 

SARS-CoV-2 genomes sequenced to date,”[10 ] suggesting that these 

codons are preserved by stabilizing selection and, therefore, may be 

associated with high fitness. In this regard, the FCS insertion structure 

appears to be well consistent with the hypothesis of natural origin and 

subsequent evolution-driven codon optimization.",0.079545455,"that, the, of, sars-cov-2, and, subsequent, to"
62581,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","aken together, this allows us to conclude 

that natural emergence remains the most plausible scenario of SARS- 

CoV-2 origin and evidence to the contrary is yet to be presented.",0.079545455,"and, the, of, to, that, this, is"
62582,"Injured or dying bats 

which felt on the cave floor can attract scavengers, which 

could be infected by consuming these bats. Several species 

of small carnivores are known to scavenge occasionally, 

such as civets (Viverridae) and raccoon dog (Nyctereutes 

procyonoides (Gray, 1834), Canidae) (IUCN 2020), in which 

the SARS-CoV has been isolated in the past (Kan et al. 

2005); other small carnivores, such as badgers and ferret 

badgers (Mustelidae) may also feed on carcasses of small 

mammals (IUCN 2020)","In another study, Lam et al. (2020) found two related lineages of 

CoVs in pangolin genome sequences sampled in Guangxi and Guang- 

dong provinces in China, which have similar genomic organizations to 

SARS-CoV-2.",0.079545455,"which, of, to, and, in, et, al."
62583,"Geography, flight patterns, and the migration range of infected bat populations also appears to  

impact where specific clusters of similar SARS-related viruses are found. As a result, closely related viruses  

should cluster together geographically. Moreover, as bats migrate and travel to different cave systems, the  

viruses they are infected with are presented with new opportunities to infect other bats that they come into  

close contact with. This in turn presents new opportunities for mutation and recombination events which  

can result in a new virus with different traits that is less closely related to its ancestors.","olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re",0.079545455,"the, bat, to, with, in, which, is"
62584,"The conditions the live animals are subjected to in wet markets create a petri dish for the spread  

of diseases.” As one group of Hong Kong based researchers described, “the presence of a large reservoir of  

SARS-CoV-like viruses in horseshoe bats, together with the culture of eating exotic mammals in southern  

China, is a time bomb.” Based on the available evidence, the most likely emergence pathway for SARS  

was that multiple horseshoe bats infected with SARS progenitor virus were captured by live animal traders  

in Yunnan Province and infected palm civets, and likely other mammals, the live animal market supply  

chain.","This finding suggests that  

natural selection might happen in pangolin and gave the virus new  

features for recognition of hACE2.",0.079545455,"the, in, for, of, that, virus, and"
62585,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.079545455,"in, a, of, to, are, that, as"
62586,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E",0.079545455,"of, related, natural, in, a, to, that"
62587,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",0.079545455,"a, of, in, that, the, suggesting, to"
62588,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.079365079,"to, a, in, pangolin, sars-cov-2"
62589,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.079365079,"a, bat, to, and, are"
62590,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China",". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2",0.079365079,"a, in, closely, related, to"
62591,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Bats of numerous globally distributed genera and species 

are now known to be the major reservoir of animal coronavi- 

ruses",0.079365079,"the, and, to, of, are"
62592,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus",0.079365079,"animals, of, virus, bats, and"
62593,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse",0.079365079,"by, of, were, identified, and"
62594,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover",0.079365079,"the, of, with, and, into"
62595,"The study of Guo  

et al. (2020), which featured deep learning algorithms,  

suggested that minks (Order, Carnivora) may serve as  

the potential intermediate host, but no experimental  

evidence was provided to support this hypothesis","As a byproduct of the impor- 

tant international surveillance work described above, in 2017, 

the therapeutic benefit of the antiviral drug remdesivir was 

suggested; it is now, in 2020, being widely used to treat per- 

sons infected with SARS-CoV-2",0.079365079,"the, of, as, was, to"
62596,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","t should be clarified that theories about a hypothetical man- 

made origin of SARS-CoV-2 have been thoroughly discredited 

by multiple coronavirus experts",0.079365079,"a, coronavirus, of, be, that"
62597,"Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.079365079,"the, have, of, and, other"
62598,"Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before","the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination",0.079365079,"the, in, of, and, probably"
62599,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020",0.079365079,"a, january, 2020, in, the"
62600,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.079365079,"the, a, are, to, and"
62601,"Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.079365079,"are, other, to, and, laboratory"
62602,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent",0.079365079,"to, the, of, and, are"
62603,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.079365079,"a, and, with, sars-cov-2, other"
62604,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","SARS-CoV-2 shares genetic properties with many other 

sarbecoviruses, lies fully within their genetic cluster, and is 

thus a virus that emerged naturally",0.079365079,"and, sars-cov-2, with, that, is"
62605,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.079365079,"bat, to, of, and, are"
62606,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence",0.079365079,"causing, of, and, the, to"
62607,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Based on virus genome se- 

quencing results and evolutionary analysis, bat has been 

suspected as natural host of virus origin",0.079365079,"results, and, of, bat, as"
62608,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.079365079,"the, of, natural, reservoir, a"
62609,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses",0.079365079,"reservoir, and, the, of, a"
62610,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor",0.079365079,"that, the, sars-cov-2, and, share"
62611,"n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.079365079,"such, as, of, and, in"
62612,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.079365079,"pangolin, in, that, protein, of"
62613,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks",0.079365079,"that, of, and, as, more"
62614,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence",0.079365079,"of, the, and, with, known"
62615,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2",0.079365079,"the, and, to, that, have"
62616,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Bats are the second most numerous mammals after the rodents. 

They have long been known as reservoirs of coronaviruses, and host 

more zoonotic viruses than any other mammalian order",0.079365079,"the, and, have, of, other"
62617,"The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.079365079,"the, for, of, into, host"
62618,"Indeed, a single amino acid change within the RBD (Q498H, Q498Y, 

N501Y) could be sufficient to allow SARS-CoV-2 to leverage mouse 

ACE2 (D","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.079365079,"a, the, be, to, ace2"
62619,"Recent research results suggest that bats or pangolins might be 

the hosts for SARS-CoV-2 based on comparative studies using its genomic sequences.","mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells",0.079365079,"that, bats, be, the, for"
62620,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.079365079,"in, of, the, were, as"
62621,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","In the case of SARS-CoV-2, Malayan pangolins (Manis javanica) 

were initially highly favored as the intermediate hosts.",0.079365079,"intermediate, as, the, of, in"
62622,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.079365079,"the, and, of, in, probably"
62623,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Wuhan has certainly been the 

turning point in the history of the pandemic, however, only as the 

predictable and probably mandatory superspreader of what had 

been quietly boiling unnoticed, in China and elsewhere, long 

before",0.079365079,"the, of, and, in, china"
62624,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","ased on the large number of infected people that were 

exposed to the wet animal market in Wuhan City, China, it is suggested that this is likely the zoonotic origin of 

COVID-19",0.079365079,"in, to, that, of, on"
62625,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.079365079,"that, of, bats, species, the"
62626,"A study by Wu et al. (2020) using a complete genome obtained 

from a patient who was a worker at a seafood market in Wuhan city, 

Hubei province, China shows that the virus is closely related to a 

group of SARS-like CoVs that were previously found present in bats in 

China","t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse",0.079365079,"by, that, the, of, bats"
62627,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.079365079,"from, to, as, and, species"
62628,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively",0.079365079,"natural, the, to, that, can"
62629,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.",0.079365079,"the, a, from, to, sequence"
62630,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","The SARS-CoV outbreak was frst  

emerged in humans in 2003, through transmissions from  

animals in open-air markets in China",0.079365079,"sars-cov, from, was, the, in"
62631,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Viral anal- 

ysis of the outbreak of SARS showed that bats are natural  

reservoirs for SARS-CoVs",0.079365079,"of, that, for, sars, the"
62632,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.079365079,"and, with, the, was, in"
62633,"he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.079365079,"from, in, at, with, the"
62634,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health",0.079365079,"to, and, highly, that, in"
62635,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.079365079,"of, to, the, are, transmitted"
62636,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.079365079,"the, of, dogs, and, to"
62637,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs",0.079365079,"and, the, be, of, sars-cov-2"
62638,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Determining  

the origin and pathway by which a zoonotic disease (i.e.,  

one that originated in animals)",0.079365079,"the, by, in, a, that"
62639,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.079365079,"on, and, that, sars-cov-2, to"
62640,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life",0.079365079,"at, and, to, on, with"
62641,"Domestic 

animals can suffer from disease as intermediate hosts that 

cause virus transmission from natural hosts to humans; for 

example, SARS-CoV and MERS-CoV crossed the species bar- 

riers into masked palm civets and camels, respectively","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.079365079,"from, as, to, and, species"
62642,"The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.079365079,"in, a, as, to, and"
62643,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.079365079,"bat, and, have, are, sars-cov-2"
62644,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi",0.079365079,"in, a, sars-cov-2, found, to"
62645,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.079365079,"available, a, of, the, that"
62646,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.079365079,"from, a, sars-cov-2, to, the"
62647,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin",0.079365079,"into, sars-cov-2, that, the, origin"
62648,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology",0.079365079,"that, of, from, coronavirus, the"
62649,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","sing 

maximum likelihood ancestral state recon- 

struction across 15 nonrecombinant regions 

of SARS-CoV-2 and closely related sarbecovi- 

rus genomes sampled from bats and pangolins 

(13)",0.079365079,"sars-cov-2, from, of, bats, and"
62650,"All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.079365079,"sars-cov-2, from, humans, are, the"
62651,"Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.079365079,"of, the, genomic, that, sars-cov-2"
62652,"pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.079365079,"were, a, sars-cov-2, the, in"
62653,"The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China","rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans",0.079365079,"the, lineage, by, from, in"
62654,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","The most probable explanation for the intro- 

duction of SARS-CoV-2 into humans involves 

zoonotic jumps from as-yet-undetermined, 

intermediate host animals at the Huanan 

market",0.079365079,"for, the, of, into, host"
62655,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Through late 2019, the 

Huanan market sold animals that are known 

to be susceptible to SARS-CoV-2 infection 

and capable of intraspecies transmission",0.079365079,"are, and, sars-cov-2, that, the"
62656,"his 

seems to have occurred with the bat-to-camel-to-human 

emergence of MERS, and possibly with SARS-CoV emer- 

gence into humans, which may have resulted from bat virus 

infection of masked palm civet cats (Paguma larvata), with 

subsequent human spillover","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.079365079,"with, the, of, and, into"
62657,"As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.079365079,"of, the, market, at, animal, and, in, with, that, coupled"
62658,"Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano","The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.",0.079365079,"humans, with, of, and, in"
62659,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","This geographic proximity is consistent 

with a separate and subsequent origin of lineage 

A at the Huanan market in late November 2019",0.079365079,"a, and, with, in, the"
62660,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","Other coronavirus epidemics and outbreaks 

in humans—including SARS-CoV-1, Middle East 

respiratory syndrome coronavirus (MERS-CoV), 

and most recently, porcine deltacoronavirus 

in Haiti—have been the result of repeated intro- 

ductions from animal hosts",0.079365079,"the, and, of, in, other"
62661,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.",0.079365079,"in, an, a, identical, and"
62662,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.079365079,"from, to, of, and, on"
62663,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms",0.079365079,"of, zoonotic, and, to, from"
62664,"SARS-CoV-2 could have been  

transmitted from an animal reservoir host to a human.Bats  

are seen as a likely reservoir host, as several studies have  

identified high genetic similarity between SARS-CoV-2  

and coronaviruses found in certain bat species found in  

China and elsewhere in South Asi","The joint WHO–China techni- 

cal report published in March  

2021 rated a zoonotic spillover as  

a “likely to very likely” source of  

the virus, cold food–chain prod- 

ucts as “possible,” and a laboratory  

incident as “extremely unlikely",0.079365079,"to, a, as, and, in"
62665,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","More than half of the  

earliest Covid-19 cases were con- 

nected to the Huanan market,  

and epidemiologic mapping re- 

vealed that the concentration of  

cases was centered there.",0.079365079,"the, of, and, that, than"
62666,"ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.079365079,"and, of, sars-cov-2, an, animal"
62667,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals",0.079365079,"and, of, in, ing, including"
62668,"Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.","Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.",0.079365079,"of, different, a, in, the"
62669,"China’s laboratory safety practices, policies, training, and 

engineering are equivalent to those of the United States and 

other developed countries,32 making viral “escape” extremely 

unlikely, and of course impossible without a viral isolate pre- 

sent","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.079365079,"laboratory, and, are, to, other"
62670,"Through genetic sequencing, epidemiologists have sug- 

gested that the virus started in bats and jumped to humans “naturally,” pos- 

sibly from people who handled infected animals at a market in Wuhan, China","Yet there are things that other experts say do not make sense if it 

was an engineered virus. Notably, SARS-CoV-2 attaches to cells 

differently from SARS-CoV-1 and is unlike any other known viruses 

used in laboratory gain-of-function research",0.079365079,"that, in, and, to, from"
62671,"he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.079365079,"with, that, the, as, sars-cov-2"
62672,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.",0.079365079,"that, the, sars-cov-2, at, as"
62673,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.",", genetic evidence following the mutations that occur in 

a virus’s genome as it replicates point to two spillover events from 

animals to humans tied to the wet market",0.079365079,"the, a, in, to, that"
62674,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.079365079,"the, of, are, transmitted, to"
62675,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",0.079365079,"analysis, that, the, is, a"
62676,"the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China","Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”",0.079365079,"the, virus, and, were, in"
62677,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”",0.079365079,"a, is, to, the, that"
62678,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV",0.079365079,"with, a, to, and, the"
62679,"mportantly, bats are also a locus for coronavirus evolution, as 

the recombination frequency of coronavirus is high. Virus variants 

can thus appear and be maintained in bats with properties that 

increase greatly their aggressiveness: a prominent example is the 

development of the ability of the virus to use the ACE2 receptor as 

an entry path into host cells","All coronaviruses have a zoonotic origin, that is, they 

infect different species of animals, giving rise to a respi- 

ratory and intestinal infection",0.079365079,"a, of, and, that, to"
62680,"Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.079365079,"a, the, that, covid-19, and"
62681,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","nitial studies compared the first COVID-19 genome to the 

bat coronavirus and verified that the sequence was 96.2% 

identical, a very high percentage",0.079365079,"coronavirus, a, and, to, the"
62682,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","a study published in the journal Nature in 201510 

warned of a possible pandemic in relation with bats",0.079365079,"a, of, in, with, the"
62683,"the 12 amino acid furin-cleavage site insertion between the 

SARS-CoV-2 spike protein’s S1 and S2 domains, which some 

have alleged to be a sign of genetic engineering, is found in 

other bat and human coronaviruses in nature, probably arising 

via naturally occurring recombination","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.079365079,"the, which, to, of, in"
62684,"the dromedary camel (Camelus dromedarius) has been identified as a bridging species of MERS-CoV that 

most likely spilled over from bats, whereas SARS-CoVs jumped to humans from civets (Paguma larvata) 

infected by maintenance bat hosts such as Rhinolophus sinicus and R. ferrumequinum","This group of 

cases resided significantly closer to the market than those 

who worked in it, which seems to indicate that they had 

been exposed to the virus in the market or close to it.",0.079365079,"the, been, of, that, to"
62685,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.079365079,"in, the, of, with, huanan"
62686,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’",0.079365079,"the, by, of, in, through"
62687,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","n September 2021, other authors such as Holmes et al. 

also studied the epidemiological relationship of the first 

242



Revista Clínica Española 223 (2023) 240---243 

cases and published their findings in the journal Cell. They 

confirmed this epidemiological relationship to the market1",0.079365079,"and, of, in, such, as"
62688,"But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets","The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.",0.079365079,"virus, from, to, of, and"
62689,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.079365079,"the, and, that, a, to"
62690,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","According to available information, SARS-CoV-2 is 

inferred to be a recombinant virus that originated from bats and was transmitted to humans, possibly 

using the pangolin as the intermediate host.",0.079365079,"the, and, a, to, that"
62691,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively",0.079365079,"the, of, with, and, that"
62692,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.079365079,"a, to, have, the, from"
62693,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","A coronavirus identified from the Malayan pangolin 

has been shown to have a 99% similarity with SARS-CoV-2",0.079365079,"the, from, a, with, to"
62694,"Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses","he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2",0.079365079,"and, can, with, to, pangolins"
62695,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations",0.079365079,"the, on, of, is, and"
62696,"One 20-country study of more than 19,000 animals 

(predominantly nonhuman primates, bats, and rodents) 

revealed that bats accounted for more than 98% of corona- 

virus detections, and that almost 9% of > 12,000 randomly 

studied bats were infected with one or more coronavirus","“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”",0.079365079,"of, animals, and, bats, virus"
62697,"In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.079365079,"the, for, is, to, and"
62698,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV",0.079365079,"host, or, and, the, may"
62699,"Studies based on the analysis of N, S, and ORF1a/1b genes have shown conserved sequences 

suggesting that SARS-CoV-2 is an animal virus, which was transmitted to humans by undergoing 

evolutionary adaptations","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.079365079,"on, the, of, and, is"
62700,"According to geographical correlation and migration 

habits of bats, it is highly possible that similar viruses related to 

RaTG13 and RmYN02 already exist in bat populations in neighbor- 

ing regions, including Southeast Asian countries","A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV",0.079365079,"and, of, it, is, bat"
62701,"A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.","Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food",0.079365079,"a, were, of, in, the"
62702,"There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.079365079,"a, genomic, with, the, bat"
62703,"Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.","a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs",0.079365079,"of, the, bats, viruses, bat"
62704,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.079365079,"the, s, of, coronavirus, for"
62705,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.",0.079365079,"to, the, for, is, of"
62706,"To clarify this contrast that SARS-CoV-2 has highest similarity to Bat-  

SL-CoV-2 when comparing the complete virus genome, but bats cannot  

be the direct origin of SARS-CoV-2, we investigated recombination  

events.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.079365079,"that, sars-cov-2, similarity, the, of"
62707,"One study also found evidence 

that circulating antibodies against pangolin-CoV reacted with the S 

protein of SARS-CoV-2,15 suggesting that pangolin may have the 

potential to act as an intermediate host of SARS-CoV-2.","he newly 

emerged novel CoV retained 99.8–99.9% nucleotide sequence 

homology with beta bat CoVs that directed the reemergence of another 

viral strain, later entitled as SARS-CoV-2 (Ren et al., 2020) and genetic 

analysis of the SARS-CoV-2 represented genetic similarity 50% with 

MERS-CoV and 80% with SARS-CoV",0.079365079,"that, with, the, of, as"
62708,"In March 2023 a team of scientists claimed to have the “best 

evidence” we are ever likely to find of how the virus that causes 

covid-19 was first transmitted to a human. The crux of this analysis 

is that DNA from raccoon dogs, wild mammals that were being sold 

live in the market for meat, was found in the same locations as 

swabs from the market that tested positive for SARS-CoV-2.",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.079365079,"of, the, are, that, from"
62709,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir",0.079365079,"the, it, that, of, from"
62710,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs",0.079365079,"recombination, of, bats, and, that"
62711,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.079365079,"the, from, sars-cov-2, are, humans"
62712,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","All SARS-CoV-2 isolated from humans to date are closely related genetically to coronaviruses isolated from bat populations,  

specifically, bats from the genus Rhinolophus.",0.079365079,"the, to, sars-cov-2, bat, are"
62713,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","The virus could have been introduced into the human population from  

an animal source in the market or an infected human could have introduced the virus to the market and the virus may have then been  

amplified in the market environment.",0.079365079,"to, and, the, market, in"
62714,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.079365079,"an, animal, and, of, sars-cov-2"
62715,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.079365079,"humans, of, that, sars-cov-2, to"
62716,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","ince there is usually very  

limited close contact between humans and bats, it is more likely that transmission of SARS-CoV-2 to humans happened through  

an intermediate host, that is another animal species more likely to be handled by humans",0.079365079,"to, sars-cov-2, that, is, of"
62717,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.079365079,"in, the, was, and, with"
62718,"A field study for the  

SARS-CoV on palm civet ruled out the possibility as the natural  

reservoir (low positive rate); instead, the prevalence of bat coro- 

navirus among wild life is high and it shares a certain sequence  

identity with the human SARS-CoV","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.079365079,"the, of, and, with, human"
62719,"genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection","Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.",0.079365079,"in, the, this, ace2, of"
62720,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","From phylogenetics analyses undertaken with available full  

genome sequences, bats appear to be the reservoir of COVID-19 virus",0.079365079,"the, of, virus, from, to"
62721,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.079365079,"the, and, to, that, are"
62722,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","Generally, coronaviruses are zoonotic viruses  

belonging to the order Nidovirales that includes three  

families, namely, Coronaviridae, Arteriviridae, and  

Roniviridae",0.079365079,"and, to, that, the, are"
62723,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively",0.079365079,"a, natural, with, to, the"
62724,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","Results of the genomic sequence analysis  

indicated that the genomic organizational structure of  

the SARS-CoV-2 coronavirus is highly similar to beta  

coronaviruses genomes",0.079365079,"of, the, that, sars-cov-2, genomic"
62725,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","enetic material of the novel coronavirus has  

approximately 89% and 82% identity with bat SARS- 

like-CoVZXC21 and human SARS-CoV,  

respectively.",0.079365079,"and, the, of, sars-, coronavirus"
62726,"Whole genome sequencing analysis of 104 strains of the COVID-19 virus isolated from  

patients in different localities with symptom onset between the end of December 2019 and  

mid-February 2020 showed 99.9% homology, without significant mutation","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.079365079,"genome, of, the, from, and"
62727,"Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.079365079,"the, of, to, and, as"
62728,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.079365079,"the, and, related, that, of"
62729,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.079365079,"such, and, to, the, of"
62730,"xample, bat SARS CoV WIV1 and bat SARS 

CoV ZC45 have the same bat origin but they are divided into 2 clusters 

(‘‘1’’ and ‘‘14’’) while all 16 SARS-CoV-2 representatives are grouped 

into cluster ‘‘14’’ with bat CoV RaTG13 and Guangdong pangol","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.079365079,"bat, sars, and, zc45, the"
62731,"In fact, a 

cluster of patients being screened for SARS-CoV-2 were recently found to be infected 

with a novel coronavirus of canine origin in Malaysia (30), suggesting that zoonotic co- 

ronavirus events may be quite common","Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)",0.079365079,"of, to, novel, coronavirus, that"
62732,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (",0.079365079,"host, in, human, or, to"
62733,"On the other hand, by analysing 

genomic features of SARS-CoV-2, i.e., mutations in the receptor binding 

domain portion of the spike protein and distinct backbone of the 

virus, Andersen, Rambaut, Lipkin, Holmes, and Garry (2020) deter- 

mined that this novel coronavirus originated through natural processes 

rather than through a laboratory manipulation.","(SARS-CoV-2) that was first isolated and identified  

in patients who were exposed at a seafood market in  

Wuhan City, Hubei Province, China on December  

2019",0.079365079,"on, in, and, that, a"
62734,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China",0.079365079,"the, has, a, sequence, in"
62735,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.079365079,"s, the, of, coronavirus, for"
62736,"The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia","Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio",0.079365079,"the, from, a, of, on"
62737,"one SARS-CoV-2-related coronavirus isolated from a Malayan pangolin 

showed 100%, 98.6%, 97.8%, and 90.7% amino acid identity with SARS-CoV-2 envelope (E), membrane 

(M), nucleocapsid (N), and spike (S) genes respectively, and therefore, whether SARS-CoV-2 has 

other reservoirs and/or intermediate hosts still remains a question to be addressed in the current 

scenario","A comprehensive analysis of the SARS-CoV-2  

genome together with that of SARS-CoV revealed the  

presence of nearly thirty ORFs and two novel inser- 

tions",0.079365079,"a, and, with, sars-cov-2, the"
62738,"olin CoV). Therefore, SARS-CoV-2 is deemed to 

have very likely originated in the same host with bat CoV RaTG13 or 

Guangdong pangolin CoV, which is bat or pangolin, re","The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,",0.079365079,"to, in, the, bat, ratg13"
62739,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","Bats are con- 

sidered to be the most likely initial hosts of SARS-  

CoV-2, while pangolins may be the intermediate hosts.",0.079365079,"the, to, of, are, sars-"
62740,"Upon virus genome sequen- 

cing, the COVID-19 was analyzed throughout the 

genome to Bat CoV RaTG13 and showed 96.2% overall 

genome sequence identity [8], suggesting that bat CoV 

and human SARS-CoV-2 might share the same ancestor","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.079365079,"the, and, that, sars-cov-2, share"
62741,"Geographically, the earliest cases centre on Wuhan’s wet market. 

Zoonotically, animals that could be infected with SARS-CoV-2 were 

present at the wet market, as confirmed by swabs collected there 

before the outbreak.","comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)",0.079365079,"the, that, sars-cov-2, at, as"
62742,"‘The clustering 

of COVID-19 cases in December around the Huanan market 

contrasts with the pattern of widely dispersed cases across 

Wuhan by early January through mid-February 2020.’’","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.079365079,"of, in, the, huanan, with"
62743,"After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.079365079,"of, reported, the, huanan, seafood"
62744,"The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T","On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.",0.079365079,"the, in, of, an, similar"
62745,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.079365079,"the, of, reported, huanan, seafood"
62746,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","After Jan. 1, 2020,  

only 8.6% of reported cases could be directly linked  

to the Huanan Seafood Market, suggesting that the  

transmission had shifted to the community.",0.079365079,"to, could, of, the, that"
62747,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.079365079,"to, the, in, of, a"
62748,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","RaTG13, the  

closest to SARS-CoV-2 genome, was isolated in 2016 from an anal  

sample of a horseshoe bat (Rhinolophus affinis) from Yunnan (Zhou et al.,  

2020a; Ge et al., 2016).",0.079365079,"in, horseshoe, to, of, sars-cov-2"
62749,"C, 

while 3 members of the Merbecovirus sub-genus (i.e., Pipistrellus bat CoV 

HKU5, Tylonycteris bat CoV HKU4 and MERS CoV) are divided into 

3 clusters (‘‘12’’, ‘‘2’’ and ‘‘4’’) or members of the Sarbecovirus cluster 

separate themselves into 2 clusters ‘‘’1’’ and ‘‘11’’, sequences of SARS- 

CoV-2 still join the cluster ‘‘11’ with other members of Sarbecovirus such 

as 3 bat viruses (bat SARS CoV ZC45, bat SARS CoV ZXC21, bat CoV 

RaTG13) and 7 pangolin","the natural origin of SARS-CoV-2  

as a recombinant between a Sarbecovirus from Malayan pangolins and  

RaTG13 from R. affinis.",0.079365079,"of, the, and, sarbecovirus, as"
62750,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","Recent studies have linked the evolution of 

human CoVs (HCoVs) to a high level of urbanization and poultry breed- 

ing, which facilitates the exchange of species and simplify crossing of 

species barriers, as well as genomic reorganization of these viruses",0.079365079,"the, of, to, as, and"
62751,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.079365079,"to, bats, suggesting, that, these"
62752,"several coronaviruses recently 

found in horseshoe bats in Laos share RBDs, which are more sim- 

ilar to that of SARS-CoV-2 based on both nucleotide (93.6% sim- 

ilarity) and amino acid (97.4% similarity) sequences compared to 

RBDs of RaTG13 (85.5% and 89.2%, respectively) and MP789 (86.6% 

and 96.9%, respectively).","Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV",0.079365079,"found, bats, are, to, that"
62753,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa","Recent SARS-CoV-2 development gives prominence to the poten- 

tial for deadly viruses hidden in wild zoonotic reservoirs and the threat 

of zoonotic spillovers",0.079365079,"in, viruses, and, sars-cov-2, the"
62754,"In Jan- 

uary 2020, Chinese officials  

cleared the market without test- 

ing live animals, but positive en- 

vironmental samples, including  

those from an animal cage and a  

hair-and-feather–removal machine,  

indicated the presence of both  

SARS-CoV-2 and Covid-suscepti- 

ble animals","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.079365079,"the, from, and, a, of"
62755,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","With the help of sequencing 

technology, bats were again assessed as a natural host for SARS-CoV- 

2, because it shares 96% of its genome with two SARS-like CoVs from 

bats, bat-SLCoVZX45 and bat-SL-CoVZX2",0.079365079,"from, two, the, of, a"
62756,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.079365079,"a, the, sars-cov-2, in, were"
62757,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","pangolins were 

considered a possible intermediate host for SARS-CoV-2 because it 

shared 99% genetic similarity with the CoV in pangolins",0.079365079,"in, with, the, sars-cov-2, cov"
62758,"The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.079365079,"the, of, related, for, in, found, to, sars-related, yunnan, that"
62759,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs",0.079365079,"for, the, of, and, were, that, found, in, with, to"
62760,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","As to the epidemic of coronaviruses, Yunnan may be consid- 

ered the most possible location of a spillover event because of the 

high potentiality of human contact to bat",0.079365079,"be, of, the, high, to"
62761,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","Prior to December 2019, no virus highly consistent to SARS-CoV- 

2 had been recorded by any laboratory, and no genome was available 

to provide the SARS-CoV-2 genome",0.079365079,"sars-cov-2, the, and, to, virus"
62762,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","Investigations into the WIV indicate that WIV is not engaged in any 

research related to SARS-CoV-2",0.079365079,"in, that, the, to, related"
62763,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","In the evolution of the virus for more than 2 years, it is not difficult to 

see that SARS-CoV-2 has been undergoing adaptive changes with the 

human host, and the cycle of this change is often within a few months",0.079365079,"is, not, a, the, in"
62764,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.079365079,"sars-cov-2, to, pangolin, in, a"
62765,"t has been shown that bats and ro- 

dents are the gene sources of most aCoVs and bCoVs, how- 

ever, avian species are the gene sources of most dCoVs and 

gCoVs by evolutionary analyse","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.079365079,"that, bats, the, of, species"
62766,"Phylogenetic studies  

map these nucleotide changes and suggest that they  

have not diverged from the bat coronavirus RaTG13 that  

was being researched at the Wuhan Institute of Virology","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.079365079,"that, from, the, coronavirus, of"
62767,"The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.","study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years",0.079365079,"the, that, found, in, with"
62768,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","the nucleotide sequences of SARS-CoV-2-related 

coronaviruses from two Rhinolophus shameli bats(RshSTT200 and Rsh- 

STT182), which were collected in Cambodia in 2010, shared 92.6% 

identity with the SARS-CoV-2 genome",0.079365079,"the, and, in, coronaviruses, of"
62769,"A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5","The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.",0.079365079,"market, with, the, to, virus"
62770,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region",0.079365079,"in, the, of, found, to"
62771,"Even though the 

authors themselves admit that these observations are also consistent 

with the scenario of natural emergence, that is, “the genetic structure 

of SARS-CoV-2 is consistent with both natural or laboratory origin”, 

they use it as an argument for the hypothesis of SARS-CoV-2 artificial 

creation.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.079365079,"the, also, sars-cov-2, as, an"
62772,"DBSCAN methods provide consistent evidence to suggest that (1) SARS- 

CoV-2 belongs to the Sarbecovirus sub-genus of the Betacoronavirus 

genus, (2) bats and pangolins may have served as the hosts for SARS- 

CoV-2, and (3) bats are the more probable origin of SARS-CoV-2 than 

pangolins.","Moreover, Kasibhatla et al. (2020) pointed out that, in addition to Bat- 

SARS-isolate (RaTG13), the SARS-CoV-2 cluster has also branched off 

from Pangolin-CoVs and evolved as an autonomous isomorphic clus- 

ter",0.079365079,"to, the, and, as, sars-cov-2"
62773,"Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats","RaTG13 S protein has 98% identities 

at the protein sequence level (Wrapp et al., 2020), of which the RBD 

region has 89.3% amino acid sequence homology with SARS-CoV-2",0.079365079,"sars-cov-2, of, the, has, with"
62774,"coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.079365079,"is, and, from, to, in"
62775,"CoV2 is an obvious chimera (though not nesessarily a lab-made 

one), which is based on the ancestral bat strain RaTG13, in which the 

receptor binding motif (RBM) in its spike protein is replaced by the 

RBM from a pangolin strain,","At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively",0.079365079,"is, the, in, by, from"
62776,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2",0.079365079,"a, in, the, that, may"
62777,"RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27","suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.",0.079365079,"to, in, the, that, may"
62778,"The distant general origin of its zoonosis can be traced back to the ecosystem 

changes that have decreased biodiversity, greatly facilitating the contacts between humans and the 

animal reservoirs that carry pathogens, including SARS-CoV-2","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.079365079,"the, to, that, have, and"
62779,"a fluorescent study, it was confirmed that the 

SARS-CoV-2 also uses the same ACE2 (angiotensin-converting 

enzyme 2) cell receptor and mechanism for the entry to host cell 

which is previously used by the SARS-CoV","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.079365079,"it, that, the, and, to"
62780,"However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature","However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (",0.079365079,"however,, the, that, found, in"
62781,"Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China","First, approximately 33 percent of the earliest known human COVID-19 cases (with symptom onset dates  

in mid- to late-December 2019) were associated with the Huanan Seafood Market in Wuhan.",0.079365079,"to, the, in, of, covid-19"
62782,"hey serve as the endemic animal reservoir to many 

viruses. Like birds, another viral reservoir, bat species have “many shared, convergent features, such as  

small body size, high population densities, close social interaction, spatial mobility, and the ability to  

colonize anthropogenic environments” which allow them “to act as viral reservoirs and to transmit viruses  

to other vertebrates, including humans","several animal species susceptible to SARS-CoV-2 were sold live and in poor animal welfare conditions at  

the market.",0.079365079,"the, animal, to, species, and"
62783,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan",0.079365079,"of, live, animal, in, markets"
62784,"Data collected on genetic evolution, receptor binding and 

pathogenesis have shown that SARS-CoV is most likely caused by bats 

by sequential recombination of bat SARS-CoVs","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.079365079,"and, that, bats, recombination, of"
62785,"That study suggests that pangolins could be possible hosts 

for SARS-CoV-2 although they are solitary animals in an endangered 

status with relatively small population sizes.","Evidence to date indicate SARS-CoV-2 could originally result from a recombination of sequences  

pre-existing in Rhinolophus bats living in the extensive limestone cave systems of Southeast Asia and South  

China. 217 It has been suggested that the SARS-CoV-2 furin cleavage site could originate from  

recombination events with as-yet-undiscovered SARS-CoV-2-related coronaviruses co-circulating in  

bats",0.079365079,"that, could, sars-cov-2, in, with"
62786,"The genome analyses of  

SARS-CoV and bat coronaviruses indicate that the  

sequences of ORF6, ORF8, and the S gene display a  

comparatively low degree of sequence conservation  

among coronaviruses in general. However, the genomes  

of bat-SL-CoVZC45 (GenBank ID: MG772933),  

bat-SL-CoVZXC21 (GenBank ID: MG772934) and  

RaTG13 (GenBank ID: MN996532) viruses are overall  

quite similar to that of SARS-CoV-2,","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.079365079,"the, of, a, in, to"
62787,"The University of North Carolina (UNC) collaborative  

study indicated that viruses encoding the SHC014 spike in a wild-type backbone  

could efficiently use multiple orthologs of the SARS receptor human ACE2, rep- 

licate efficiently in primary human airway cells and achieve in vitro titers equiv- 

alent to epidemic strains of SARS-CoV.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.079365079,"the, of, in, a, to"
62788,"Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.079365079,"a, of, zoonotic, the, to"
62789,"Similarly, the RBD region RmYN02 and ZC45 coron- 

aviruses also has a multi-segment deletion, resulting in the 

decreased ability to bind ACE2 receptors (Fig. 1), suggesting that 

these highly homologous bat coronaviruses are not direct ances- 

tors of SARS-CoV-2, but a common sister group.","Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.",0.079365079,"the, a, in, to, of"
62790,"Bats are important natural hosts of many emerging infectious 

disease-causing pathogens and harbor a large diversity of coron- 

aviruses,4 several of which are related to zoonotic pathogens that 

cause severe disease in humans, such as severe acute respiratory 

syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)- 

CoV, human CoVs NL63, and 229E","The horseshoe bats species most likely to serve as the reservoir of SARS-CoV-2 include:  

the Intermediate Horseshoe Bat (Rhinolophus affinis), the Malayan Horseshoe Bat (Rhinolophus  

malayanus), the Least Horseshoe Bat (Rhinolophus pusillus), and the Marshall’s Horesebat (Rhinolophus  

marshalli).",0.079365079,"bats, of, and, to, as"
62791,"Florence Debarre, a senior researcher at the Institute of Ecology 

and Environmental Sciences in Paris, reviewed the data and told 

BBC World Service, “We saw the results appear on our screens, and 

it was: raccoon dog, raccoon dog, raccoon dog, raccoon dog. We 

found animals and virus [together]. That does not prove that the 

animals were infected, but that is the most plausible interpretation 

of what we’ve seen.”","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.079365079,"the, and, in, virus, were"
62792,"SARS-CoV had spread widely from its 

as-yet-undetermined reservoir into intermediate hosts, such 

as civets, ferret badgers, and raccoon dogs, and genetically 

diversified before it made multiple jumps to humans. This 

possibility was not accounted for by the authors of the pre- 

print (14) that suggested that SARS-CoV-2 may have been 

adapted in a laboratory to infect humans.","the progenitor virus for SARS and other viruses closely related to SARS were  

discovered in southern China",0.079365079,"and, to, for, the, in"
62793,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.079365079,"in, the, a, are, and"
62794,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.079365079,"in, different, the, of, a"
62795,"A role of the 

Chinese military at WIV has also been proposed. Lab leak 

theories are often bolstered by racist tropes that suggest 

that epidemiological, genetic, or other scientific data have 

been purposefully withheld or altered to obscure the origin 

of the virus","Within this region of Southeast Asia and Southern China, “very similar SARS-CoV-2-like viruses  

are shared by different bat species, suggesting a possible circulation of viruses between different species  

living sympatrically in the same caves.",0.079365079,"a, of, the, are, by"
62796,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.079365079,"a, the, of, bat, in"
62797,"However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible","esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material",0.079365079,"the, in, believe, that, of"
62798,"Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market","closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago",0.079365079,"of, with, a, to, known"
62799,"These single mutations, such as N501Y, S477N, N439K and 

Y453F, significantly increased the affinity of RBD to hACE2 to enhance 

the pathogenicity and transmissibility (Amanat et al., 2021; Barton 

et al., 2021; Han et al., 2021). Therefore, it can be deduced that the 

emergence of SARS-CoV-2 is simply the result of natural adaptation.","he  

closest related bat coronavirus to SARS-CoV-2, as measured by highest average genetic similarity is  

BANAL 52 which is approximately 96.8% similar to SARS-CoV-2 at the whole genome level.",0.079365079,"as, the, to, sars-cov-2, is"
62800,"ats are the natural reservoir of a wide 

variety of CoVs, including SARS-CoV-like and MERS- 

CoV-like viruses","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.079365079,"the, natural, reservoir, of, a"
62801,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.079365079,"of, the, to, related, in, found, that, yunnan, for, sars-related"
62802,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","The importance of geographic restrictions on the location of closely related SARSr-CoV is corroborated by the  

successful search for the likely natural reservoir of SARS. In 2013, WIV researchers found a virus 95.6% similar to  

SARS in discovery of SARS-related virus, WIV1, in a cave in Yunnan Provence. In 2017, WIV researchers discovered,  

through additional sampling, that the same cave actually contained “all of the genetic building blocks” necessary for  

SARS.",0.079365079,"additional, that, the, is, a"
62803,"er. In line with the results obtained 

by using hierarchical clustering in Fig. 7, those obtained in Fig. 8B and 

8C using the DBSCAN method give us the confidence to confirm that 

SARS-CoV-2 is part of the Sarbecovirus sub-genus. Fig. 8D shows that 

bat CoV RaTG13 and Guangdong pangolin CoV are closest to SARS- 

CoV-2 as they join with 16 SARS-CoV-2 representatives in cluster ‘‘","scientists have shown through experiments that the RBD of BANAL-52 binds with greater affinity  

to human ACE2 than SARS-CoV-2.",0.079365079,"with, the, to, that, of"
62804,"In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5","experiments conducted to date suggest that BANAL viruses mostly replicate in human  

intestinal cells, rather than respiratory cells.",0.079365079,"in, that, to, human, than"
62805,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.",0.079365079,"the, and, two, viruses, have"
62806,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","There are a few other closely related coronaviruses that, due to genomic recombination events  

common in coronaviruses, may share a more recent common ancestor with SARS-CoV-2 than RaTG-13. 

These include the bat coronaviruses RmYN02, RpYN06, RacCS203, and PrC31.",0.079365079,"a, the, genomic, with, bat"
62807,"more than 780 partial coro- 

navirus genetic sequences were identified from bats of 

41 species infected by α- and of 31 species infected by 

β-coronaviruse","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.079365079,"were, identified, of, by, and"
62808,"Compared with the known 

SARS-CoV and MERS-CoV genome, SARS-CoV-2 is 

closer to the SARS-like bat CoVs in terms of the whole 

genome sequence","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.079365079,"with, the, known, and, of"
62809,"Peer-reviewed evidence available to the public points  

to the hypothesis that SARS-CoV-2 emerged as a  

result of spillover into humans from a natural origin","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.079365079,"available, the, that, a, of"
62810,"In this context, it can  

be assumed that the recombination between Bat- and Pangolin-CoVs  

happened deep in an ancestry of the bat lineage.","Available evidence, collected by a team of researchers examining the origins of SARS-CoV-2,  

found that 19 COVID-19 cases were identified by Wuhan clinicians between December 18 and December  

30, 2019 using the limited VPUE case definition.393 Approximately half of these cases were associated with  

the Huanan Seafood Market, suggesting a “genuine preponderance” connection of the earliest known cases  

with the Huanan Market.3",0.079365079,"that, the, between, and, of"
62811,"possible”hypothesis positing that people contracted  

SARS-CoV-2 through contact with contaminated food,  

potentially including frozen, imported foodstuffs. SARS- 

CoV-2 has been identified on frozen food, its packaging, 

and cold-chain products(items stored at controlled  

temperatures to preserve and extend shelf life","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.079365079,"with, on, and, at, to"
62812,"Comparative ge- 

nomic analysis primarily based on sequence inserts  

identified in the S protein of a coronavirus isolated  

from the pangolin (Order, Pholidota; Family, Mani- 

dae) suggested that these mammals were most likely  

the intermediate hosts for cross-species transmissio","The sample sequenced by Vision Medicals was taken from a 65- 

year-old deliveryman who worked at the Huanan Seafood Market and admitted to the Central Hospital of  

Wuhan on December 18 with pneumonia",0.079365079,"on, the, of, a, from"
62813,"The virus from the market 

shares 99.980% to 99.993% nucleotide identity with the human iso- 

late HCoV/Wuhan/IVDC-HB-01.","A survey of 508 wet market workers in Guangdong Province revealed that 13% of wild animal  

traders tested positive for SARS antibodies with 72% of palm civet traders testing positive for antibodies.542 

By contrast only 5% of vegetable traders had SARS antibodies.543 None of the animal traders who tested  

positive for SARS antibodies reported being sick, suggesting either asymptomatic transmission or exposure  

to a less severe virus closely related to SARS.5",0.079365079,"the, virus, market, to, with"
62814,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.079365079,"the, of, and, to, dogs"
62815,"SARS-CoV-2  

receptor-binding domain to human ACE2 receptor  

protein in animal host or in human after zoonotic  

transfer (","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.079365079,"to, human, in, host, or"
62816,"Looking back, we see clear similarities between SARS-CoV-2 and 

SARS-CoV. Both occurrences of the SARS-CoVs have been linked to 

markets selling live wild animals and related species, especially civet 

cats and pangolin animal traders who worked in 2003 but were not 

diagnosed with SARS, while had high levels of SARS-CoV immunoglob- 

ulin G (IgG) found in their serum (13% overall, over 50% of traders spe- 

cializing in civet cats). Further serological surveys found that Yunnan 

residents living near the bat caves were 3% positive for SARS-related 

coronavirus (SARSr-CoV), indicating that spillover events may have 

occurred in zoonotic CoVs","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.079365079,"and, of, the, to, in, were, with, found, that, for"
62817,"Additional analysis initially suggests that the probability is 

low that SARS-CoV-2 is a laboratory construct or intentionally engineered","Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.",0.079365079,"suggests, that, the, a, or"
62818,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","As a result of the Shenzhen market survey, public health investigators conducted serological studies  

of palm civets at animal farms and live animal markets throughout China. These studies were aided by the  

mass culling of palm civets undertaken by government officials in an effort to stop the spread of SARS as  

it provided investigators with a large number of animal samples to examine and test. However, investigators  

struggled to find evidence of SARS infected palm civets in animal farms. For example, one serological  

study found that none of the 108 samples taken from palm civets at live animal farms tested positive for  

SARS.549 By contrast, 14 of 18 samples collected from palm civets in animal markets in Guangdong tested  

positive.550 In another study, the majority of 91 palm civets and 15 racoon dogs taken from a Xinyuan  

animal market tested positive for SARS.551 However, in the same study, none of the 1,107 palm civets  

sampled from “25 farms in 12 province” were positive from SARS.552 The prevalence of SARS infections  

among palm civets located in live markets, coupled with the absence of infected palm civets at animal farms  

suggested palm civets were an intermediate host for SARS, not the reservoir host",0.079365079,"the, of, animal, coupled, with, and, market, that, at, in"
62819,"Due to the high sequence 

homology with a coronavirus isolated from bats, SARS-CoV-2 

is considered a zoonotic origin coronavirus.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.079365079,"to, the, sequence, a, from"
62820,"even though lineages A 

and B had nearly identical haplotypes, their 

MRCA likely existed in an animal reservoir.","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.079365079,"a, and, identical, in, an"
62821,"Zhou et al. (2020) has found the high degree of homology 

of BatCoV RaTG13 to SARS-CoV-2 in the RdRp region","In December 2005, the role of palm civets as an intermediate host of SARS was confirmed when  

an investigation of a SARS outbreak at a restaurant found that virus samples taken from infected humans  

were identical to virus sample taken from palm civets at the restaurant.553 Moreover, both the human and  

palm civet samples were more closely related to the variant of SARS containing the 29-nucleotide sequence  

than later human adapted variants.5",0.079365079,"found, the, of, to, in"
62822,"The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)","By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia",0.079365079,"the, southern, of, china, a, to, in, and, were, virus"
62823,"Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples","Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses",0.079365079,"and, from, at, the, market, in, of, on, a, animal"
62824,"Collectively, this evidence suggests that palm civets were infected from bats somewhere in the  

South China wet market supply chain, such a warehouse, while in transit, or at wet markets. Stressed  

animals stored in dense and unhygienic conditions shed large amounts of viruses. “The main source of  

cross-species transmission in the animal trading chain (including warehouses, transportation vehicles,  

markets) may come from contaminated feces, urine, blood, or aerosols.”567 Moreover, cages at wet markets  

are often stacked on top of each, further facilitating cross-species transmission of viruses","Chinese Center for Disease Control and Prevention (CCDC) dispatched an epidemiological team, together  

with experts from Hubei Provincial CDC and Wuhan Municipal CDC, to collect environmental samples at  

the Huanan Seafood Market in the early morning of January 1, 2020.”640 According to the CCDC, its team  

arrived from Beijing on January 1, 2020 and collected 585 environmental samples from sewers, stalls and  

a garbage truck. Thirty-three of them tested positive for the virus. There was no mention of any animal  

samples",0.079365079,"from, in, the, market, a, at, and, of, animal, on"
62825,"On January 7th, the virus was recognized as a  

coronavirus that has about 95% symmetry with coronary bat virus and about 70% similarity to  

SARSCoV","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.079365079,"the, a, with, and, to"
62826,"closest known relatives to SARS-CoV-2, all of which appear  

to have descended from a common ancestor shared with SARS-CoV-2 around 20 to 70 years ago","Out of 174 diagnosed cases of COVID-19 with onset during December 2019, 93 cases had a history  

of exposure to any markets. Thirty-eight early cases reported having exposure to other Wuhan area markets  

and 8 cases reported exposure to the Huanan Market and other Wuhan markets.643 Forty-seven cases were  

only exposed to the Huanan Market. In total, approximately 28% of the earliest known cases had a direct  

exposure to the Huanan Market",0.079365079,"known, to, of, a, with"
62827,"t is also highly unlikely that SARS-CoV-2 was released from 

a laboratory by accident because no laboratory had the virus 

nor did its genetic sequence exist in any sequence database 

before its initial GenBank deposition (early January 2020","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.079365079,"a, the, in, january, 2020"
62828,"Ini- 

tially, it was suggested that the patients infected with Wuhan coro- 

navirus induced pneumonia in China may have visited the seafood 

market where live animals were sold or may have used infected 

animals or birds as a source of food","A leaked CCDC Report dated January 22, 2020 shows 44 positive samples collected  

on January 1 and 12, 2020 were linked to 21 specific vendors, 19 of which were located in the western side  

of the Huanan market.",0.079365079,"the, in, were, a, of"
62829,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The association between the earliest known COVID-19 cases and the Huanan Seafood  

Market is one of the strongest pieces of evidence suggesting a natural zoonotic spillover origin to COVID- 

19",0.079365079,"of, to, is, a, the"
62830,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","Live animal sales at markets are a known zoonotic risk and this association in some ways parallels the  

spillover events that led to the 2002-2003 SARS epidemic",0.079365079,"that, to, a, in, the"
62831,"Genome se- 

quence alignment has revealed a 79.5% sequence  

identity between SARS-CoV-2 and SARS-CoV and a  

remarkable 93.1% identity with the sequence of the  

RaTG12 virus isolated from a bat (Rhinolophus af- 

finis) residing in Yunnan Province, China","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.079365079,"and, with, the, of, in"
62832,"no such arguments have been provided by Segreto and Deigin 

in their initial manuscript and response to our commentary.[9] Mean- 

while, the evidence in favor of SARS-CoV-2 natural origin has been 

growing and is reviewed elsewhere","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.079365079,"and, in, the, of, is"
62833,"hypothesis is especially appealing to lab origin proponents: the fact that 

RaTG13 has been identified by researchers from the WIV provides an 

additional link between the lab and the pandemic. But this scenario 

appears to be implausible.","The “paradox” is that many of the first known human COVID-19 cases are associated with the  

Huanan Seafood Market and the genomic sequences of these cases fall within lineage B.687 In addition, all  

but one environmental sample collected at the Huanan market also fall within lineage B.",0.079365079,"is, the, that, and, but"
62834,"The animal sources of SARS-CoV-2 infections are bats and  

SARS-CoV-2 can be transmitted to cats, pangolins, and dogs","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.079365079,"the, of, sars-cov-2, and, be"
62835,", it has been proposed that the majority of 

human coronaviruses are derived from the bat reservoir","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.079365079,"it, that, the, of, from"
62836,"from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario","Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl",0.079365079,"from, and, would, be, the"
62837,"coronaviruses SARS-CoV and MERS-CoV, and a  

third novel pandemic-causing coronavirus, SARS- 

CoV-2, belonging to the beta coronavirus group.  

Remarkably, bats could be the natural reservoirs of  

the three human coronaviruses with palm civet,  

dromedary camels or pangolin acting as intermediate  

amplifying and transmitting host, respectively","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.079365079,"a, to, the, natural, with"
62838,"Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets","SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.",0.079365079,"that, the, natural, for, wildlife"
62839,"SARS-CoV-2 should be of natural origin, based on the recent 

emergence of bat-borne and pangolin-borne zoonotic viruses with 

high homology, the discovery of furin cleavage site similar to SARS- 

CoV-2 in RmYN02, virus infection experiments, and genetic evolu- 

tion analysis of the binding ability of ACE2 to the RBD of S protein 

in many potential animals.","WIV discovered a virus sequence (RaTG13) that shows 

a 96.2% genomic sequence identity match with the SARS-CoV-2 

genome, in its archived bat samples collected in 2013.[2",0.079365079,"sars-cov-2, the, with, in, virus"
62840,"The virus responsible for COVID-19 

has a single-stranded positive-sense RNA genome of about 30 kb, which has 74% to 99% identity 

with that of the coronavirus from the pangolin (Manis javanica) and horseshoe bat (Rhinolophus 

sinicus) (Bat-CoVRaTG13), respectively","Thus, the high-affinity  

binding of the SARS-CoV-2 spike protein  

to human ACE2 is most likely the result of  

natural selection on a human or human-like  

ACE2 that permits another optimal binding  

solution to arise. This is strong evidence  

that SARS-CoV-2 is not the product of  

purposeful manipulation.",0.079365079,"the, a, of, to, that"
62841,"Most scientists feel that a naturally occurring 

event was most likely the cause of the SARS-CoV-2 outbreak and 

subsequent pandemic spread,” he says. “The evidence is strong but 

is still circumstantial, and we need to keep an open mind about the 

origins of covid-19.”","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.079365079,"that, a, the, is, to"
62842,"SARS-CoV-2 may 

also recognize ACE2 in a variety of animal species (except mice and 

rats). Pigs, ferrets, cats and non-human primates contain a larger num- 

ber of residues that favour the interaction of SARS-CoV-2 with ACE2 

and therefore serve as animal models or intermediate hosts for the 

SARS-CoV-2","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.079365079,"may, in, a, that, the"
62843,"suggest 

that turtles (Chrysemys picta bellii, Chelonia mydas and Pelodiscus sinen- 

sis) may be potential intermediate hosts for SARS-CoV-2 transmission 

to humans other than pangolins and snakes based on the interaction 

between the key amino acids in RBD with ACE2.","RaTG13,  

sampled from a Rhinolophus affinis bat1 

, is  

~96% identical overall to SARS-CoV-2, its  

spike diverges in the RBD, which suggests  

that it may not bind efficiently to human  

ACE27",0.079365079,"that, may, to, the, in"
62844,"protein sequences alignment and 

phylogenetic analysis [15] showed that similar residues 

of receptor were observed in many species, which pro- 

vided more possibility of alternative intermediate hosts, 

such as turtles, pangolin and snacks","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.079365079,"protein, that, of, in, pangolin"
62845,"s the 

entire genome of the 2019-novel coronavirus is more than 80% 

similar to the previous human SARS-like bat CoV, previously used 

animal models for SARS-CoV can be utilized to study the infectious 

pathogenicity of SARS-CoV-2.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.079365079,"the, of, is, to, for"
62846,"Transgenic human ACE2 mice  

and Rhesus monkey intranasally challenged by this virus isolate induced multifocal  

pneumonia with interstitial hyperplasia. The COVID-19 virus was subsequently detected  

and isolated in the lung and intestinal tissues of the challenged animals.","genome1 

, some pangolin coronaviruses exhibit  

strong similarity to SARS-CoV-2 in the RBD,  

including all six key RBD residues21 (Fig. 1).  

This clearly shows that the SARS-CoV-2 spike  

protein optimized for binding to human-like  

ACE2 is the result of natural selection",0.079365079,"ace2, this, the, in, of"
62847,"On Dec. 26, 2019, Dr. Ji-xian ZHANG in the  

Hubei Hospital of Integrated Traditional Chinese and  

Western Medicine identified an elderly couple with  

pneumonia of unknown etiology, and subsequently  

found five patients with similar clinical presentations  

on the next day; most of these individuals reported  

exposure at the Huanan Seafood Market.","The presence  

in pangolins of an RBD very similar to that  

of SARS-CoV-2 means that we can infer  

this was also probably in the virus that  

jumped to humans. T",0.079365079,"in, the, of, an, similar"
62848,"Phylogenetically, the genome sequence  

of the novel coronavirus that came from Wuhan city,  

was very close to Bat SARS‐like viruses, such as SL‐ 

ZC45 and SL-ZXC21 (87.6 and 87.7%, respectively),  

and more distantly related to SARS and MERS (79%  

and 51.8%, respectively)","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.079365079,"the, of, that, and, related"
62849,"esearchers believe that the cohabitation of multiple bat species 



36 

Marshall.Senate.Gov 

THE ORIGINS OF COVID-19 

in the same caves increases likelihood of recombination events as multiple closely related, but distinct  

viruses can infect a single bat giving viruses the opportunity to exchange genetic material","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.079365079,"believe, that, the, of, in"
62850,"the CGG codon is rarely used by the sarbecoviruses, 

the naturally occurring Rabbit coronavirus HKU14 (NCBI Reference 

Sequence: NC_017083.1) also has a CGGCGG sequence encoding two 

arginines, demonstrating that such coding sequences can emerge in 

beta coronaviruses in nature","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.079365079,"the, is, that, in, coronaviruses"
62851,", ORF1ab contains natural 

insertions of three amino acids (PAA) at the S1/S2 cleavage site of 

the spike protein, resulting in a furin cleavage site similar to those 

of SARS-CoV-2, strongly indicating that such insertion events can 

occur naturally in animal beta-coronaviruses","However, since we observed  

all notable SARS-CoV-2 features, including  

the optimized RBD and polybasic cleavage  

site, in related coronaviruses in nature, we  

do not believe that any type of laboratory- 

based scenario is plausible",0.079365079,"of, the, cleavage, in, that"
62852,"At the nucleotide 

(93.6%) and amino acid (97.4%) levels in the RBD sequences, the coro- 

navirus found in horseshoe bats from Laos is the most similar one to 

SARS-CoV-2, followed by RaTG13 (85.5% and 89.2%, respectively) and 

MP789 (86.6% and 96.9%, respectively","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.079365079,"and, in, from, is, to"
62853,"Zhang 

and Holmes (2020) also highlight a similarity of about 85% between 

SARS-CoV-2 and RaTG13 in their receptor binding domain, which is 

an important region of the viral genomes for binding the viruses to the 

human angiotensin-converting enzyme 2 receptor.","coronavirus disease (COVID-19) is easily trans- 

missible and very contagious from animals to human beings 

through aerosols, especially in individuals who have been in 

close contact or shared common spaces, especially enclosed 

or poorly ventilated spaces",0.079365079,"and, in, is, to, human"
62854,"However, it has been 

found in ex vivo tests that, unlike the early isolated WHU01, variants 

beta and gamma are able to bind and use mouse ACE2, suggesting that 

these variants may have obtained the ability to infect mice through 

evolution (","However, the region that binds ACE2 resembles a novel virus  

found in pangolins, a strange-looking animal sometimes called a scaly anteater.  

This provides additional evidence that the coronavirus that causes COVID-19  

almost certainly originated in nature",0.079365079,"however,, found, in, the, that"
62855,"In Fig. 7D, these viruses however are separated into 2 different 

clusters (‘‘3’’ and ‘‘2’’) while all 16 SARS-CoV-2 representatives are 

grouped together with bat CoV RaTG13 and Guangdong pangolin CoV 

in cluster ‘‘15’’. This demonstrates that the difference between the same 

origin viruses (e.g. bat SARS CoV WIV1 and bat SARS CoV ZC45) is 

larger than the difference between SARS-CoV-2 and bat CoV RaTG13 

(or Guangdong pa",", the 

amino acid sequence of the tentative receptor-binding domain re- 

sembles that of SARS-CoV, indicating that these viruses might use the 

same receptor [",0.079365079,"these, viruses, that, the, same"
62856,"Chinese rhi- 

nolophid bats were also found to harbour genetically differentiated 

CoVs related to SARS-CoV (Rhinolophus spp.), suggesting that these ani- 

mals are hosts for this novel HCoV","Viruses similar to the Severe Acute Respiratory 

Syndrome Coronavirus 2 (SARS-CoV-2) have been discov- 

ered in bats of the genus Rhinolophus and in the Sunda 

pangolin, Manis javanica Desmarest, 1822, suggesting that 

these animals have played a key role in the emergence of 

the Covid-19 outbreak in the city of Wuhan, China",0.079365079,"bats, to, suggesting, that, these"
62857,"Two BANAL viruses less closely related to SARS-CoV-2, BANAL-116 and BANAL-247, have a  

partial furin cleavage site at the S1/S2 junction, which is the same location where SARS-CoV-2’s furin  

cleavage site is located.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.079365079,"two, viruses, and, have, the"
62858,"SARS-CoV-2 is a natural virus that found its way into 

humans through mundane contact with infected wildlife 

that went on to cause the most consequential pandemic 

for over a century.","Present evidence indicates that Rhinolophus bats are the 

natural reservoir of all sarbecoviruses, and that two 

divergent SARS-CoV-2-like viruses have circulated in 

southern China (at least in Guangxi and Guangdong 

provinces) between August 2017 and March 2019 in captive 

pangolins destined for sale in wildlife markets",0.079365079,"natural, that, wildlife, the, for"
62859,"study suggests that direct transmission of SARS- 

CoV-2 from bats to humans without an intermediate host is unlikely. 

A SARS-CoV-2-like coronavirus found in a dead Malayan pangolin 

shares 91.02% homology with SARS-CoV-2 in an analysis of coron- 

avirus sequences in species worldwide over the past 2 years","The results reveal that the same SARS-CoV-2- 

like virus can be found in animals with distinct haplotypes, 

which means that they were probably captured in different 

Southeast Asian regions.",0.079365079,"that, found, in, with, the"
62860,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","there is no doubt that one or 

several species of Rhinolophus constitute the natural 

reservoir of sarbecoviruses.",0.079365079,"the, of, species, that, or"
62861,"rejects a 

single-introduction origin of the pandemic 

from a lineage A virus. We resolved this para- 

dox by showing that early SARS-CoV-2 genomic 

diversity and epidemiology are best explained 

by at least two separate zoonotic transmissions, 

in which lineage A and B progenitor viruses 

were both circulating in nonhuman mam- 

mals before their introduction into humans","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.079365079,"the, from, lineage, by, in"
62862,"ZC45 

and ZXC21 from R. sinicus in Zhejiang,7 RpYN06 from R. pusillus 

in Yunnan, China,8 RSHSTT200 and STT182 from R. shameli in Cam- 

bodia,9 RacCS203 from R. acuminatus in Thailand,10 and Rc-o319 

from R. cornutus in Japan,11 were recently found to be closely 

related to SARS-CoV-2, indicating that the distribution of SARS- 

CoV-2-related coronavirus is relatively wide, and bats are very 

likely to be the natural hosts of SARS-CoV-2","The SARS- 

CoV-2 lineage is only represented by three bat viruses, all 

isolated from Rhinolophus species collected in China",0.079365079,"from, in, the, sars-, is"
62863,"According to previous studies on  

the SARS- and MERS-CoV, epidemiologic investigations, their  

natural reservoir is bat, while palm civet or raccoon dog may  

be the intermediate (or susceptible) host for SARS-CoV and  

the dromedary camel for MERS-CoV","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.079365079,"the, and, or, may, host"
62864,"a group of researchers sug- 

gested snakes be the possible host, however, after genomic similar- 

ity findings of novel coronavirus with SARS-like bat viruses 

supported the statement that not snakes but only bats could be 

the key reservoirs","Some caves can host hundreds or even thousands of 

bats. Promiscuity and intense flight activity during the pre- 

hibernation period in swarming sites (where bats mate 

during the autumn) may favour the transmission of viruses 

between bat individuals and between bat species.",0.079365079,"of, the, bat, viruses, bats"
62865,"The presence of potential animal reservoirs, 

coupled with the timing of the lineage B primary 

case and the geographic clustering of early cases 

around the Huanan market (39), support the 

hypothesis that SARS-CoV-2 lineage B jumped 

into humans at the Huanan market in mid- 

November 2019.","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.079365079,"of, with, and, humans, in"
62866,"“Many infectious diseases are “zoonotic” . . .  

[which means] they start in animals but jump to humans,” “This is true of the  

COVID-19 virus which genetic sequencing has shown originated in bats and  

was naturally transmitted to humans,”","Direct transmission to humans or other mammals can be 

done through contact with body parts, saliva, urine, or 

faeces of bats, or alternatively through inhalation of liquid 

droplets and aerosol particles in cave housing thousands of 

bats and their guano",0.079365079,"in, to, of, bats, and"
62867,"Critically, for the purposes of determining whether raccoon dogs and civets were the intermediate  

host species that introduced the virus into humans, the virus collected from palm civets and raccoon dogs  

contained a 29 nucleotide sequence only found in the earliest human SARS cases.548 Taken together, this  

evidence suggests that SARS likely crossed the species barrier from palm civets or raccoon dogs into  

humans with the 29 nucleotide sequence dropping out as SARS adapted to humans.","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.079365079,"the, and, from, humans, to"
62868,"Since lineage B cases and environmental samples predominate at the Huanan Seafood  

Market, it would therefore then be likely that the market, or its supply chain, was the location for the  

zoonotic spillover of SARS-CoV-2 into humans.697 In reaching this conclusion, the Pekar Study draws  

heavily from a companion study by Worobey et. al. (“Worobey study”) published concurrentl","from bats to humans is possible, direct contact between 

bats and hunters would be the best scenario",0.079365079,"and, the, would, be, from"
62869,". Human SARS-CoV and SARS-CoV-2 

are closely related to numerous bat and pangolin coronaviruses in a viral 

genetic grouping called sarbecoviruses, which contains many other 

viruses very closely related to SARS-CoV and SARS-CoV-2","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.079365079,"and, are, to, bat, a"
62870,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.079365079,"and, are, of, bat, to"
62871,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.079365079,"of, from, and, to, on"
62872,"The virus has an approximate 30 kb single-stranded 

positive-sense RNA genome, which is 74.5% to 99% identical to that of SARS-CoV, CoV-pangolin, 

and the coronavirus the from horseshoe bat.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.079365079,"virus, to, of, and, from"
62873,"The current leading  

hypothesis is that the bat-derived virus evolved to  

infect pangolins; after a series of mutations and re- 

combination events, it has been transmitted to humans.","But how can be possible a 

virus transmission from a bat to another species? First, 

hunters usually catch not only bats but a large diversity of 

species, and some are more valuable if kept alive as they 

will be then sold a higher price on wildlife markets",0.079365079,"virus, to, a, of, and"
62874,"he infected pangolins 

exhibit pathological symptoms similar to humans suffering from COVID-19, and their blood circulating 

antibodies can react with the spike protein of SARS-CoV-2","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.079365079,"pangolins, to, and, can, with"
62875,"Due to recombination event, the key residues of  

RBD from Pangolin-CoV integrated to Bat-SL-CoV-2, then zoonotic  

transmission occurred by a recombinant virus with capability to bind to  

hACE2.","Although pan- 

golins (Pholidota, Manidae) feed mainly on ants and ter- 

mites, they can also come into contact with bats. Since 

many ant species are known to feed on carrion, pangolins 

can lick dead or dying bats on a cave floor, and may be then 

contaminated by sarbecoviruses",0.079365079,"to, then, by, a, with"
62876,"Presence of susceptible (palm civets, raccoon dogs &  

mink) live animal markets in Wuhan","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.079365079,"of, live, animal, markets, in"
62877,"By 2005, the discovery of a large number of genetically diverse SARS-related viruses in multiple  

species of horseshoe bats, led scientists to conclude that SARS “originated in horseshoe bats with civets  

acting as the intermediate amplifying and transmitting host.” 559 However, efforts to locate the direct  

descendant of SARS, or progenitor virus, in bats were unsuccessful in the years following the pandemic.560 

Specifically, researchers were unable to find a SARS-related virus sufficiently similar to SARS that also  

used ACE2 receptors as it mechanism for cellular entry.561 As general scientific interest in coronaviruses  

ebbed, Chinese researchers continued to conduct large scale viral prospecting exhibitions to Southern China  

and South East Asia","The southern 

regions of China have a dietary tradition favouring freshly 

slaughtered game meat, which implies a huge trafficking 

industry dedicated to live animal trading in specialized 

markets, called wet markets (Shi and Wang 2011). Various 

wild animals of Shenzhen market were tested, and a virus 

identical at 99.8% to the SARS-CoV was isolated in the 

masked palm civet (Paguma larvata, Viverridae)",0.079365079,"the, of, a, in, to, and, were, virus, southern, china"
62878,"comparative studies revealed that the similarity be- 

tween the nucleic acid sequences of the genomes of  

SARS-CoV-2 and SARS-CoV reached 79.5%, notably  

73.8%–74.9% at the two receptor domains, both of  

which share ACE2 as a common receptor (Zhou P  

et al., 2020b; Zhu N et al., 2020)","Two 

viruses of the SARS-CoV-2 lineage have been isolated in 

Sunda pangolins (Manis javanica) obtained from wildlife 

traffic (so their exact geographic origin is unknown) in 

Guangdong and Guangxi provinces",0.079365079,"the, of, sars-cov-2, and, two"
62879,"In the year 2012, a novel highly  

pathogenic Middle East Respiratory Syndrome coronavirus  

(MERS-CoV) was identifed in humans, demonstrating that  

the coronaviruses are transmitted from animals to humans  

at any time and with unexpected consequences for the pub- 

lic health","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.079365079,"in, the, from, at, with"
62880,"Samples  

from early cases in humans also  

contained two different SARS- 

CoV-2 lineages. Although only  

one lineage spread globally, the  

existence of multiple lineages  

suggests that a SARS-CoV-2 epi- 

demic in animals may have led  

to multiple spillover events.","he virus isolated from 

pangolins seized in Guangdong province is similar at 

97.4% with SARS-CoV-2 in the amino acid sequence of the 

receptor binding domain (RBD) of the S protein (located on 

the surface of the viral envelope)",0.079365079,"from, in, the, of, sars-cov-2"
62881,"the viruses causing SARS,MERS, and COVID- 

19 are all members of enormous groups of bat coronaviruses 

distributed globally, and that many of these viruses are function- 

ally preadapted to human emergence","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.079365079,"the, causing, and, of, to"
62882,"here were at least two zoonotic 

jumps of SARS-CoV-2 into humans from pet 

hamsters in Hong Kong (55) and dozens from 

minks to humans on Dutch fur farms","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.079365079,"zoonotic, of, from, and, to"
62883,"Therefore, whether the COVID-19 pandemic is the result of the natural zoonotic  

spillover of SARS-CoV-2 or due to a research-related incident, SARS-CoV-2 or a closely related progenitor  

virus resides somewhere in nature.","Not only do CoVs affect several species, causing a broad spectrum of disease, but some of them 

also have a zoonotic potential and the ability to jump from one reservoir species to a different species,



Animals 2020, 10, 2377 3 of 41 

including humans, usually through a bridging species.",0.079365079,"the, of, zoonotic, to, a"
62884,"Studies on genome sequences obtained from 

early patients in Wuhan city in China suggest the probable bat